Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Northwest Fisheries Science Center Fisheries Research

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 219

[Docket No. 151027994-6421-01]

RIN 0648-BF47

Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Northwest Fisheries Science Center Fisheries Research

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Proposed rule; request for comments.

SUMMARY:

NMFS' Office of Protected Resources has received a request from NMFS' Northwest Fisheries Science Center (NWFSC) for authorization to take marine mammals incidental to fisheries research conducted in the Pacific Ocean off the northwest United States, over the course of five years from the date of issuance. As required by the Marine Mammal Protection Act (MMPA), NMFS is proposing regulations to govern that take, and requests comments on the proposed regulations.

DATES:

Comments and information must be received no later than July 13, 2016.

ADDRESSES:

You may submit comments on this document, identified by NOAA-NMFS-2016-0060, by any of the following methods:

•

Electronic submission:

Submit all electronic public comments via the federal e-Rulemaking Portal. Go to

www.regulations.gov,

enter 0648-BF47 in the “Search” box, click the “Comment Now!” icon, complete the required fields, and enter or attach your comments.

•

Mail:

Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East West Highway, Silver Spring, MD 20910.

Instructions:

NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Attachments to electronic comments will be accepted in Microsoft Word or Excel or Adobe PDF file formats only. To help NMFS process and review comments more efficiently, please use only one method to submit comments. All comments received are a part of the public record and will generally be posted on

www.regulations.gov

without change. All personal identifying information (

e.g.,

name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information. NMFS will accept anonymous comments (enter N/A in the required fields if you wish to remain anonymous).

FOR FURTHER INFORMATION CONTACT:

Ben Laws, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Availability

A copy of NWFSC's application and any supporting documents, as well as a list of the references cited in this document, may be obtained by visiting the Internet at:

www.nmfs.noaa.gov/pr/permits/incidental/research.htm.

In case of problems accessing these documents, please call the contact listed above (see

FOR FURTHER INFORMATION CONTACT

).

Purpose and Need for Regulatory Action

This proposed rule, to be issued under the authority of the Marine Mammal Protection Act (MMPA) (16 U.S.C. 1361

et seq.

), would establish a framework for authorizing the take of marine mammals incidental to the NWFSC's fisheries research activities in the California Current and Pacific Northwest.

The NWFSC collects a wide array of information necessary to evaluate the status of exploited fishery resources and the marine environment. NWFSC scientists conduct fishery-independent research onboard NOAA-owned and operated vessels or on chartered vessels. A few surveys are conducted onboard commercial fishing vessels, but the NWFSC designs and executes the studies and funds vessel time.

We received an application from the NWFSC requesting five-year regulations and authorization to take multiple species of marine mammals. Take would occur by Level B harassment incidental to the use of active acoustic devices, as well as by visual disturbance of pinnipeds, and by Level A harassment, serious injury, or mortality incidental to the use of fisheries research gear. The regulations would be valid from 2016 to 2021. Please see “Background” below for definitions of harassment.

Legal Authority for the Proposed Action

Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs the Secretary of Commerce to allow, upon request, the incidental, but not intentional taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region for up to five years if, after notice and public comment, the agency makes certain findings and issues regulations that set forth permissible methods of taking pursuant to that activity, as well as monitoring and reporting requirements. Section 101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR part 216, subpart I provide the legal basis for issuing this proposed rule containing five-year regulations, and for any subsequent Letters of Authorization. As directed by this legal authority, this proposed rule contains mitigation, monitoring, and reporting requirements.

Summary of Major Provisions Within the Proposed Rule

The following provides a summary of some of the major provisions within the proposed rulemaking for the NWFSC fisheries research activities. We have preliminarily determined that the NWFSC's adherence to the proposed mitigation, monitoring, and reporting measures listed below would achieve the least practicable adverse impact on the affected marine mammals. They include:

• Required monitoring of the sampling areas to detect the presence of marine mammals before deployment of certain research gear.

• Required use of acoustic deterrent devices on surface trawl nets.

• Required implementation of the mitigation strategy known as the “move-on rule mitigation protocol” which incorporates best professional judgment, when necessary during certain research fishing operations.

Background

Paragraphs 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1371 (a)(5)(A) and (D)) direct the Secretary of Commerce to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed authorization is provided to the public for review.

An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact

on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such takings are set forth. NMFS has defined “negligible impact” in 50 CFR 216.103 as “an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.”

Except with respect to certain activities not pertinent here, the MMPA defines “harassment” as: Any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild [Level A harassment]; or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering [Level B harassment].

Summary of Request

On August 10, 2015, we received an adequate and complete request from NWFSC for authorization to take marine mammals incidental to fisheries research activities. We received an initial draft of the request on January 2, 2015, followed by a revised draft on April 28, 2015. On August 28, 2015 (80 FR 52256), we published a notice of receipt of NWFSC's application in the

Federal Register

, requesting comments and information related to the NWFSC request for thirty days. We received comments jointly from The Humane Society of the United States and Whale and Dolphin Conservation, which we considered in development of this proposed rule and which are available on the Internet at:

www.nmfs.noaa.gov/pr/permits/incidental/research.htm.

NWFSC proposes to conduct fisheries research using trawl gear used at various levels in the water column, hook-and-line gears (including longlines with multiple hooks, rod and reel, and troll deployments), purse seine/tangle net gear, and other gear. If a marine mammal interacts with gear deployed by NWFSC, the outcome could potentially be Level A harassment, serious injury (

i.e.,

any injury that will likely result in mortality), or mortality. Therefore, NWFSC has pooled the estimated number of incidents of take that could reasonably result from gear interactions, and we have assessed the potential impacts accordingly. NWFSC also uses various active acoustic devices in the conduct of fisheries research, and use of these devices has the potential to result in Level B harassment of marine mammals. Level B harassment of pinnipeds hauled out may also occur, as a result of visual disturbance from vessels conducting NWFSC research. The proposed regulations would be valid for five years from the date of issuance.

NWFSC requests authorization to take individuals of sixteen species by Level A harassment, serious injury, or mortality (hereafter referred to as M/SI + Level A) and of 34 species by Level B harassment.

Description of the Specified Activity

Overview

The NWFSC collects a wide array of information necessary to evaluate the status of exploited fishery resources and the marine environment. NWFSC scientists conduct fishery-independent research onboard NOAA-owned and operated vessels or on chartered vessels. A few surveys are conducted onboard commercial fishing vessels, but the NWFSC designs and executes the studies and funds vessel time. The NWFSC proposes to administer and conduct approximately 36 survey programs over the five-year period. The gear types used fall into several categories: Towed nets fished at various levels in the water column, longline and other hook and line gear, seine nets, traps, and other gear. Only use of trawl nets, hook and line gears, and purse seine nets are likely to result in interaction with marine mammals. Many of these surveys also use active acoustic devices.

The federal government has a responsibility to conserve and protect living marine resources in U.S. waters and has also entered into a number of international agreements and treaties related to the management of living marine resources in international waters outside the United States. NOAA has the primary responsibility for managing marine finfish and shellfish species and their habitats, with that responsibility delegated within NOAA to NMFS.

In order to direct and coordinate the collection of scientific information needed to make informed fishery management decisions, Congress created six regional fisheries science centers, each a distinct organizational entity and the scientific focal point within NMFS for region-based federal fisheries-related research. This research is aimed at monitoring fish stock recruitment, abundance, survival and biological rates, geographic distribution of species and stocks, ecosystem process changes, and marine ecological research. The NWFSC is the research arm of NMFS in the northwest region of the United States. The NWFSC conducts research and provides scientific advice to manage fisheries and conserve protected species in the geographic research area described below and provides scientific information to support the Pacific Fishery Management Council and numerous other domestic and international fisheries management organizations.

Dates and Duration

The specified activity may occur at any time during the five-year period of validity of the proposed regulations. Dates and duration of individual surveys are inherently uncertain, based on congressional funding levels for the NWFSC, weather conditions, or ship contingencies. In addition, cooperative research is designed to provide flexibility on a yearly basis in order to address issues as they arise. Some cooperative research projects last multiple years or may continue with modifications. Other projects only last one year and are not continued. Most cooperative research projects go through an annual competitive selection process to determine which projects should be funded based on proposals developed by many independent researchers and fishing industry participants.

Specified Geographical Region

The NWFSC conducts research in the Pacific Northwest and California Current within three research areas: The California Current Research Area (CCRA), Puget Sound Research Area (PSRA), and Lower Columbia River Research Area (LCRRA). Please see Figures 1-2 through 1-4 in the NWFSC application for maps of the three research areas. We note here that, while the NWFSC specified geographical region extends outside of the U.S. Exclusive Economic Zone (EEZ), from the Mexican EEZ (not including Mexican territorial waters) north into the Canadian EEZ (not including Canadian territorial waters), the MMPA's authority does not extend into foreign territorial waters. In addition to general knowledge and other citations contained herein, this section relies upon the descriptions found in Sherman and Hempel (2009) and Wilkinson

et al.

(2009). As referred to here, productivity refers to fixated carbon (

i.e.,

g C/m

2

/yr) and can be related to the carrying capacity of an ecosystem.

The NWFSC conducts research surveys off the Pacific coast within the California Current Large Marine Ecosystem (CCE). This region is considered to be of moderately high

productivity. Sea surface temperature (SST) is fairly consistent, ranging from 9-14 °C in winter and 13-15 °C in summer. Major biogeographic breaks are found at Point Conception and Cape Mendocino, and the region includes major estuaries such as San Francisco Bay, the Columbia River, and Puget Sound. The latter two are areas of research focus for NWFSC and are described in further detail below. The shelf is generally narrow in the CCE, and shelf-break topography (

e.g.,

underwater canyons) creates localized upwelling conditions that concentrate nutrients into areas of high topographic relief.

The California Current determines the general hydrography off the coast of California. The current is part of the North Pacific Gyre, related to the anticyclonic circulation of the central North Pacific and brings cool waters southward. In general, an area of divergence parallels the coast of California, with a zone of convergence 200-300 km from the coastline. The current moves south along the western coast of North America, beginning off southern British Columbia and flowing southward past Washington, Oregon and California, before ending off southern Baja California (Bograd

et al.,

2010). Extensive seasonal upwelling of colder, nutrient-rich subsurface waters is predominant in the area south of Cape Mendocino and supports large populations of whales, seabirds and important fisheries. Significant interannual variation in productivity results from the effects of this coastal upwelling as well as from the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. Both oscillations involve transitions from cooler, more productive conditions to warmer, less productive conditions, but over different timescales.

On the shoreward side of the California Current, the California Current Front separates cold, low-salinity upwelled waters from the warmer, saltier waters close to shore. Offshore frontal filaments transport the frontal water across the entire ecosystem. In winter, the wind-driven Davidson Current is the dominant nearshore system, and its associated front forms along the boundary between inshore subtropical waters and colder offshore temperate and subarctic waters. Surface flow of the California Current appears to be diverted offshore at Point Conception and again at Punta Eugenia, while semi-permanent eddies exist south of these headlands.

NWFSC conducts research programs specific to two major estuaries of the CCE: Puget Sound and the Columbia River. Offshore of these estuaries, the CCE is affected by the Heceta Bank, which rises to within 80 m of the ocean surface and causes coastal eddies, and underwater canyons (

e.g.,

Juan de Fuca Canyon), which create upwelling conditions driving high biologic productivity. This portion of the region is also affected by high amounts of runoff from the Columbia and Fraser Rivers (the latter being the largest freshwater input to Puget Sound). The river plumes stimulate primary productivity, with the Columbia River plume creating a large surface lens of lower-salinity water in the spring and summer and the Fraser River plume carrying nutrients northwards past Vancouver Island year-round.

Puget Sound, with more than 8,000 km

2

of marine waters and estuarine environment and a watershed of more than 33,000 km

2

, is one of the largest estuaries in the United States and is the only inland sea with fjords in the continental United States. Puget Sound is a place of great physical and ecological complexity and productivity, with many diverse and important habitat types. Kelp beds and eelgrass meadows cover almost 1,000 km

2

, while other major habitat types include subtidal and intertidal wetlands, mudflats, and sandflats (Gustafson

et al.,

2000). Concentrations of nutrients (

i.e.,

nitrates and phosphates) are consistently high throughout most of Puget Sound, largely due to the flux of oceanic water into the basin (Harrison

et al.,

1994), with circulation driven by tides, gravity, and freshwater influx. The average surface water temperature is 12.8 °C in summer and 7.2 °C in winter (Staubitz

et al.,

1997), but surface waters frequently exceed 20 °C in the summer and fall. With nearly six million people (doubled since the 1960s), Puget Sound is also heavily influenced by human activity.

The Columbia River is the largest in the Pacific Northwest, draining a watershed of 671,000 km

2

. The Columbia River estuary encompasses more than 325 km

2

and is one of the largest on the west coast. Dams, diking, and dredging have dramatically altered the hydrologic processes that historically shaped the wetlands of the lower Columbia River. Prior to these alterations, many of the riverine islands and much of the floodplain were inundated several times a year, typically in December and again in May or June. Operation of dams has substantially reduced peak river flows and has nearly eliminated flooding in many low-lying areas. Dredging of shipping channels has required disposal of massive quantities of sediments, resulting in creation of new islands, filling of many former wetlands, and changing shoreline sediment types (OWJV, 1994).

The LCRRA includes the Columbia River from its mouth, west of Astoria, OR, to the Bonneville Dam at river mile (RM) 145. Downstream of approximately RM 120, the river widens to include a broad floodplain and elongated islands that divide the river and form sloughs and side-channels in the formerly marshy lowlands. The floodplain expands around the confluence with the Willamette River (which accounts for approximately fifteen percent of Columbia River flow) at RM 101. Downstream of approximately RM 35 the channel is dotted with low islands of deposited sediments and widens into several broad bays (OWJV, 1994).

Detailed Description of Activities

The federal government has a trust responsibility to protect living marine resources in waters of the United States. These waters extend to 200 nm from the shoreline and include the EEZ. The U.S. government has also entered into a number of international agreements and treaties related to the management of living marine resources in international waters outside of the EEZ (

i.e.,

the high seas). To carry out its responsibilities over U.S. and international waters, Congress has enacted several statutes authorizing certain federal agencies to administer programs to manage and protect living marine resources. Among these federal agencies, NOAA has the primary responsibility for protecting marine finfish and shellfish species and their habitats. Within NOAA, NMFS has been delegated primary responsibility for the science-based management, conservation, and protection of living marine resources under statutes including the Magnuson-Stevens Fishery Conservation and Management Act, the Pacific Salmon Treaty Act, and the Endangered Species Act, as well as under treaties with Native American tribes inside the EEZ off the Washington Coast.

Within NMFS, six regional fisheries science centers direct and coordinate the collection of scientific information needed to inform fisheries management decisions. Each Fisheries Science Center is a distinct entity and is the scientific focal point for a particular region. NWFSC conducts research and provides scientific advice to manage fisheries and conserve protected species along the U.S. west coast, including estuaries and freshwater systems of Puget Sound and the major rivers in Washington and Oregon. NWFSC provides scientific information to support the Pacific Fishery Management Council and other

domestic and international fisheries management organizations.

The NWFSC collects a wide array of information necessary to evaluate the status of exploited fishery resources and the marine environment. NWFSC scientists conduct fishery-independent research onboard NOAA-owned and operated vessels or on chartered vessels. A few surveys are conducted onboard commercial fishing vessels, but the NWFSC designs and executes the studies and funds vessel time. The NWFSC proposes to administer and conduct approximately 36 survey programs over the five-year period.

The gear types used fall into several categories: Towed nets fished at various levels in the water column, longline and other hook and line gear, seine nets, traps, and other gear. Only use of trawl nets, hook and line gears, and purse seine nets are likely to result in interaction with marine mammals. Many of these surveys also use active acoustic devices. These surveys may be conducted aboard NOAA-operated research vessels (R/V), including the

Bell M. Shimada, Reuben Lasker,

and assorted other small vessels owned by NWFSC, aboard vessels owned and operated by cooperating agencies and institutions, or aboard charter vessels.

In the following discussion, we first summarily describe various gear types used by NWFSC and then describe specific fisheries and ecosystem research activities conducted by the NWFSC. This is not an exhaustive list of gear and/or devices that may be utilized by NWFSC but is representative of gear categories and is complete with regard to all gears with potential for interaction with marine mammals. Additionally, relevant active acoustic devices, which are commonly used in NWFSC survey activities, are described separately in a subsequent section. Please see Appendix A of NWFSC's draft EA for further description, pictures, and diagrams of research gear and vessels.

Trawl nets

—A trawl is a funnel-shaped net towed behind a boat to capture fish. The codend (or bag) is the fine-meshed portion of the net most distant from the towing vessel where fish and other organisms larger than the mesh size are retained. In contrast to commercial fishery operations, which generally use larger mesh to capture marketable fish, research trawls often use smaller mesh to enable estimates of the size and age distributions of fish in a particular area. The body of a trawl net is generally constructed of relatively coarse mesh that functions to gather schooling fish so that they can be collected in the codend. The opening of the net, called the mouth, is extended horizontally by large panels of wide mesh called wings. The mouth of the net is held open by hydrodynamic force exerted on the trawl doors attached to the wings of the net. As the net is towed through the water, the force of the water spreads the trawl doors horizontally apart. The top of a net is called the headrope, and the bottom is called the footrope.

The trawl net is usually deployed over the stern of the vessel and attached with two cables (or warps) to winches on the deck of the vessel. The cables are played out until the net reaches the fishing depth. Commercial trawl vessels travel at speeds of 2-5 kn while towing the net for time periods up to several hours. The duration of the tow depends on the purpose of the trawl, the catch rate, and the target species. At the end of the tow the net is retrieved and the contents of the codend are emptied onto the deck. For research purposes, the speed and duration of the tow and the characteristics of the net must be standardized to allow meaningful comparisons of data collected at different times and locations. Active acoustic devices (described later) incorporated into the research vessel and the trawl gear monitor the position and status of the net, speed of the tow, and other variables important to the research design. NWFSC research trawling activities utilize pelagic (or midwater) and surface trawls, which are designed to operate at various depths within the water column but not to contact the seafloor, as well as bottom trawls.

NWFSC also uses beam trawls, a type of bottom trawl in which the horizontal opening of the net is provided by a heavy beam mounted at each end on guides or skids that travel along the seabed. On sandy or muddy bottoms, a series of `tickler' chains are strung between the skids ahead of the net to stir up the fish from the seabed and chase them into the net. On rocky grounds, these ticklers may be replaced with chain matting. Several trawls are towed, one on each side of the vessel. NWFSC attaches video camera systems to some beam trawls. The trawls are towed along the seafloor at speeds of 1-1.5 kn.

Longline

—Longline vessels fish with baited hooks attached to a mainline (or groundline). The length of the longline and the number of hooks depend on the species targeted, the size of the vessel, and the purpose of the fishing activity. Hooks are attached to the mainline by another thinner line called a gangion. The length of the gangion and the distance between gangions depends on the purpose of the fishing activity. Depending on the fishery, longline gear can be deployed on the seafloor (bottom longline), in which case weights are attached to the mainline, or near the surface of the water (pelagic longline), in which case buoys are attached to the mainline to provide flotation and keep the baited hooks suspended in the water. Radar reflectors, radio transmitters, and light sources are often used to help fishers determine the location of the longline gear prior to retrieval.

A commercial pelagic longline can be over 100 km long and have thousands of hooks attached, although longlines used for research surveys are shorter. The pelagic longline gear used for NWFSC research surveys typically use 500 hooks attached to a mainline less than 2 km long, with snap-on gangions less than 1 m long spaced at intervals of approximately 3 m. There are no internationally-recognized standard measurements for hook size, and a given size may be inconsistent between manufacturers. Larger hooks, as are used in longlining, are referenced by increasing whole numbers followed by a slash and a zero as size increases (

e.g.,

1/0 up to 20/0). The numbers represent relative sizes, normally associated with the gap (the distance from the point tip to the shank). Because pelagic longline gear is not anchored to the seafloor, it floats freely in the water and may drift considerable distances between the time of deployment and the time of retrieval. Bottom longlines used for commercial fishing can be up to several miles long, but those used for NWFSC research use shorter lines with approximately thirty hooks per line.

The time period between deployment and retrieval of the longline gear is the soak time. Soak time is an important parameter for calculating fishing effort. For commercial fisheries the goal is to optimize the soak time in order to maximize catch of the target species while minimizing the bycatch rate and minimizing damage to target species that may result from predation by sharks or other predators.

Other hook and line gear

—Hook and line is a general term used for a range of fishing methods that employ short fishing lines with hooks in one form or another (as opposed to longlines). This gear is similar to methods commonly used by recreational fishers and may generally include handlines, hand reels, powered reels, rod/pole and line, drop lines, and troll lines, all using bait or lures in various ways to attract target species. NWFSC uses barbed or barbless circle hooks used depending on the needs of the research (

i.e.,

to retain fish

or release them with minimal injury) and would typically deploy multiple lines at once.

Other nets

—NWFSC surveys utilize various small, fine-mesh, towed nets designed to sample small fish and pelagic invertebrates. These nets can be broadly categorized as small trawls (which are separated from large trawl nets due to discountable potential for interaction with marine mammals; see “Potential Effects of the Specified Activity on Marine Mammals and Their Habitat”) and plankton nets.

1. The Tucker trawl is a medium-sized single-warp net used to study pelagic fish and zooplankton. The Tucker trawl consists of a series of nets that can be opened and closed sequentially via stepping motor without retrieving the net from the fishing depth. It is designed for deep oblique tows where up to three replicate nets can be sequentially operated by a double release mechanism and is typically equipped with a full suite of instruments, including inside and outside flow meters, CTD, and pitch sensor.

2. NWFSC also uses various neuston nets, which are frame trawls towed horizontally at the top of the water column in order to capture neuston (

i.e.,

organisms that inhabit the water's surface).

3. An epibenthic tow sled is an instrument designed to collect organisms that live on bottom sediments. It consists of a fine mesh net, typically 1 m x 1 m opening with 1-mm mesh, attached to a rigid frame with runners to help it move along the substrate.

The remainder of nets described here are plankton nets, which usually consist of fine mesh attached to a weighted frame which spreads the mouth of the net to cover a known surface area in order to sample plankton and fish eggs from various parts of the water column. Plankton nets used by NWFSC generally employ 20 to 500-μm mesh.

4. Ring nets are used to capture plankton with vertical tows. These nets consist of a circular frame and a cone-shaped net with a collection jar at the codend. The net, attached to a labeled dropline, is lowered into the water while maintaining the net's vertical position. When the desired depth is reached, the net is pulled straight up through the water column to collect the sample.

5. Bongo nets are towed through the water at an oblique angle to sample plankton over a range of depths. Similar to ring nets, these nets typically have a cylindrical section coupled to a conical portion that tapers to a detachable codend constructed of nylon mesh. During each plankton tow, the bongo nets are deployed to depth and are then retrieved at a controlled rate so that the volume of water sampled is uniform across the range of depths. In shallow areas, sampling protocol is adjusted to prevent contact between the bongo nets and the seafloor. A collecting bucket, attached to the codend of the net, is used to contain the plankton sample. Some bongo nets can be opened and closed using remote control to enable the collection of samples from particular depth ranges. A group of depth-specific bongo net samples can be used to establish the vertical distribution of zooplankton species in the water column at a site. Bongo nets are generally used to collect zooplankton for research purposes and are not used for commercial harvest.

Seine nets

—Seine nets typically hang vertically in the water with the bottom edge held down by weights and the top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine or from a boat and are actively fished, in comparison with gillnets which may be similar but fish passively. NWFSC uses both purse seines and beach seines. Beach seines are deployed from shore to surround all fish in the nearshore area, and typically have one end fastened to the shore while the other end is set out in a wide arc and brought back to the beach. This may be done by hand or with a small boat. The beach seines used in NWFSC research are 1.8-2.4 m in depth and 36-45 m in length, with mesh sizes of less than 25 mm. A pole seine is a type of beach seine deployed by hand. The net is pulled along the bottom by hand as two or more people hold the poles and walk through the water. Fish and other organisms are captured by walking the net towards shore or tilting the poles backwards and lifting the net out of the water. The NWFSC pole seine is 12 x 2 m, with mesh smaller than 25 mm.

Purse seines are typically much larger and are deployed from vessels. Commercial fishers use purse seines to capture schooling pelagic species by encircling the fish and then using a line at the bottom that enables the net to be closed like a purse. Commercial purse seines may be more than 2,000 m in length and 200 m in depth, varying in size according to vessel, mesh size, and target species. The purse seines employed by NWFSC are between 150-450 m in length, between 9-27 m in depth and have mesh sizes ranging from 11-33 mm depending on the location in the net.

Tangle net

—Tangle nets are similar to gillnets (

i.e.,

vertical panels of netting buoyed with floats at top and weighted at bottom) but are typically considered to be more selective and less lethal than gillnets, using smaller mesh sizes to allow fish to be caught by nose or jaw and thus able to be resuscitated. NWFSC uses a 180 x 12 m tangle net with 108-mm mesh.

Traps and pots

—Traps and pots are submerged, three-dimensional devices, often baited, that permit organisms to enter the enclosure but make escape extremely difficult or impossible. Most traps are attached by a rope to a buoy on the surface of the water and may be deployed in series. The trap entrance can be regulated to control the maximum size of animal that can enter, and the size of the mesh in the body of the trap can regulate the minimum size that is retained. In general, the species caught depends on the type and characteristics of the pot or trap used. NWFSC uses fyke traps and sablefish (

Anoplopoma fimbria

) pots.

Fyke traps are bag-shaped nets held open by frames or hoops, often outfitted with wings and/or leaders to guide fish towards the entrance of the actual trap. Fyke trap wings can be set up to form a barrier across a channel, trapping fish that attempt to proceed through the channel. As the tide ebbs, fish eventually seek to leave the wetland channel and are then trapped. NWFSC sets fyke traps with 6.4-mm mesh in estuarine channels that are approximately 1-5 m wide. NWFSC uses conical sablefish pots to catch fish. These pots consist of a conical-frustum-shaped frame covered in nylon netting with one or more funnel-shaped entrance tunnels and are 1.2 m in diameter.

Conductivity, temperature, and depth profilers (CTD)

—A CTD profiler is the primary research tool for determining chemical and physical properties of seawater (see Figure A-22 of NWFSC's EA for a photograph). A shipboard CTD is made up of a set of small probes attached to a large (1-2 m diameter) metal rosette wheel. The rosette is lowered through the water column on a cable, and CTD data are observed in real time via a conducting cable connecting the CTD to a computer on the ship. The rosette also holds a series of sampling bottles that can be triggered to close at different depths in order to collect a suite of water samples that can be used to determine additional properties of the water over the depth of the CTD cast. A standard CTD cast, depending on water depth, requires two to five hours to complete. The data from a suite of samples collected at different depths are often called a depth profile. Depth profiles for different variables can be

compared in order to glean information about physical, chemical, and biological processes occurring in the water column. Salinity, temperature, and depth data measured by the CTD instrument are essential for characterization of seawater properties.

Other instruments

—NWFSC uses a continuous water pump with a thermosalinograph to measure sea surface conductivity and temperature. The pump continuously pumps seawater from a depth of 3 m near the bow of the research vessel to the thermosalinograph which sends the temperature and conductivity data to a shipboard computer. To collect physical environmental data in riverine and estuarine habitats, NWFSC uses water level and temperature loggers. These devices are placed underwater at fixed locations where they continuously record data.

Video cameras

—The NWFSC uses several apparatuses to collect underwater videos of benthic habitats and organisms. These include a CamPod, a video camera sled, video beam trawls and a remotely operated vehicle (ROV). Each apparatus includes a video camera system consisting of a digital video camera, lights, and a power source. The CamPod is a lightweight, three-legged platform equipped with a video system and adequate illumination. The frame holds a 35-mm stills camera system and two video cameras—one that provides a forward-looking oblique view and a high-resolution video camera that faces downward. Designed primarily for making images of the benthic environment, the configuration of the device focuses on minimizing its hydrodynamic presence in the field of view of the cameras. The CamPod is deployed vertically through the water column on a cable and is intended to view one point on the bottom.

A video camera sled consists of a video camera system mounted on a metal frame with runners to allow it to move along the benthic substrate. A research vessel tows the sled along the seafloor, allowing the camera to capture video footage of the benthic environment. NWFSC uses a video ROV to capture underwater footage of the benthic environment. The ROV is controlled and powered from a surface vessel. Electrical power is supplied through an umbilical or tether which also has fiber optics which carry video and data signals between the operator and the ROV. This enables researchers on the vessel to control the ROV's position in the water with joysticks while they view the video feed on a monitor.

Section 1.6 of the NWFSC's application provides a detailed account of all surveys planned by NWFSC in the CCRA, PSRA, and LCRRA. We note here that active acoustic systems are used for data acquisition purposes only within the CCRA. Many of these surveys also use small trawls, plankton nets, and/or other gear; however, only gear with likely potential for marine mammal interaction is described. Table 1.1 of NWFSC's application provides summary information related to these surveys. Please see those sections for full details of survey activity planned by NWFSC. Here we provide relevant information related to a subset of survey programs with potential for marine mammal interactions.

1.

Bycatch Reduction Research

—Bycatch reduction research programs are conducted in the CCRA, from southern Oregon to Canada. This intermittent research is conducted aboard chartered commercial fishing vessels, involving thirty to ninety days at sea (DAS) from April to October, in order to test gear improvements in commercial trawls. Specific trawl gear tested varies based on survey objectives and vessel chartered. Projected annual effort is approximately forty bottom trawls per year (50-1,000 m depth; up to four hour tows), up to sixty midwater trawls per year (50-1,000 m depth; average two hour tow), and up to an additional sixty bottom trawls per year with a double-rigged shrimp trawl (100-300 m depth; thirty to eighty minute tows).

2.

Flatfish Broodstock Collection

—In order to collect fish for aquaculture development, intermittent surveys are conducted aboard charter fishing vessels or small NOAA vessels. These surveys use commercial bottom trawls and hook and line and are conducted in Puget Sound and along the Washington coast for approximately twenty DAS. The hook and line portion involves approximately eighteen trips per year with up to twelve lines in the water at once, using barbed circle hooks. Total hook-hours are dependent on target species and catch per unit effort (CPUE). Trawls (6-24 per year) are deployed for approximately ten minutes each at depths greater than 10 m.

3.

Groundfish Bottom Trawl Survey

—This survey is conducted annually from May to October for at least 190 DAS, extending throughout the U.S. west coast, and is designed to monitor groundfish distribution and biomass. Commercial fishing vessels are used to deploy Aberdeen bottom trawls (5 x 15 m mouth opening) for approximately 750 tows per year (55-1,280 m depth; fifteen minute tows).

4.

Hake Acoustic Survey/Camera Trawl Research

—These surveys are conducted annually from March to September (up to 80 DAS) from southern California to southeast Alaska, following hake (

Merluccius productus

) distribution in order to measure abundance using active acoustic systems and trawl gear. NOAA vessels as well as commercial fishing vessels may be used, deploying Aleutian Wing midwater trawls (100 m headrope) for 225 trawls per year (30-1,500 m depth; variable tow duration) and Poly Nor'Easter bottom trawls (36 m footrope x 27 m headrope) for five to ten trawls per year (variable depth and duration). Results of the survey inform assessments of several rockfish (

Sebastes

spp.) populations and may be used in assessments of central California salmon productivity. It is either conducted on a NOAA ship or a charter vessel and requires about 45 survey days. The protocols for this survey include underway multi-frequency active acoustic devices, modified-Cobb midwater trawls, various plankton tows, and CTD profiles at fixed stations. The modified-Cobb trawl is deployed for fifteen-minute tows at 2 kn during dark hours at 15-30 m depth.

5.

Juvenile Salmon Pacific Northwest Coastal Survey

—This survey complements similar surveys conducted by NMFS' Southwest Fisheries Science Center (SWFSC), is conducted annually in May, June, and September (36 DAS) from Newport, OR, to Cape Flattery, WA, aboard commercial fishing vessels, and is designed to assess ocean conditions and growth, relative abundance, and survival of juvenile salmon (

Oncorhynchus

spp.). The survey deploys the Nordic 264 surface trawl (30 m wide x 20 m deep) for 180 trawls per year (surface to 30 m depth; thirty minute tow).

6.

Marine Fish Broodstock Collection, Sampling, and Tagging

—This variable research program occurs annually for approximately ten DAS aboard charter fishing vessels along the Washington coast. In order to collect fish, commercial bottom trawls (ten trawls per year; 50-1,000 m depth, up to four hour tow duration), pelagic longline, and hook and line gear are used. Approximately thirty longline sets per year, using five hundred barbed circle hooks per set, are set at approximately 215-915 m depth (mainline length 1,370-1,830 m; soak time approximately three hours). Hook and line effort involves eight lines with barbed circle hooks deployed for six-hour fishing days for a total of ninety hours or 720 hook-hours per year.

7.

Northern Juvenile Rockfish Survey

—This survey complements similar surveys conducted by SWFSC, is conducted annually from May to June from Cape Mendocino, CA, to Cape Flattery, WA, for fifteen to thirty DAS, and targets the pelagic phase of juvenile rockfish using a modified Cobb midwater trawl net (26 m headrope; 12 x 12 m opening). It is typically conducted on a charter vessel, with approximately one hundred trawls per year (fifteen-minute tows at night; 15-30 m depth).

8.

Video Beam Trawl Collaborative Research

—This survey is conducted monthly along the continental shelf from Oregon to Washington aboard partner research vessels or chartered commercial vessels. The survey uses a 2-m beam trawl system with open codend outfitted with a digital video camera to assess the seasonal and interannual distribution of young-of-the-year groundfishes and the potential impacts of hypoxia and requires twenty DAS annually with twenty to forty trawl deployments of ten minutes each.

9.

Coastwide Groundfish Hook and Line Survey in Untrawlable Habitat

—This survey to monitor groundfish distribution and abundance along the U.S. west coast is conducted annually from May to October aboard charter sportfishing vessels (250 DAS). Hook and line gear is deployed by rod and reel, with approximately 1,000 sites visited annually. At each site, each of three anglers deploys a line with five hooks for a five-minute soak and repeats this five times. Therefore, 75 total hooks are deployed per site for five minutes each, yielding an annual total of 6,250 hook-hours.

10.

Near Coastal Ocean Purse Seining

—This study of salmon habitat use is conducted monthly from May to September nearshore near the mouth of the Columbia River aboard chartered commercial vessels (12 DAS). Purse seines (228 x 18 m or 305 x 12 m) are deployed for 75 sets per year, with generally less than one hour set duration.

11.

Beam Trawl Survey to Evaluate Effects of Hypoxia

—Conducted only in Puget Sound, with twenty DAS in summer and fall, this survey is designed to examine effects of hypoxia on demersal fish in Hood Canal. A 2-m beam trawl, primarily with open codend and outfitted with a video camera, is deployed for one tow per each of ten sites per season for a total of twenty tows (each tow at varying depths [30, 60, 90 m]; ten minute duration).

12.

Marine Fish Collections Including Flatfish

—This survey, conducted only in Puget Sound aboard charter vessels with variable monthly effort (fifteen DAS), utilizes commercial bottom trawls. Annual effort is forty trawls at 50-1,000 m depth and tow duration is up to four hours.

13.

Movement Studies of Puget Sound Species

—These surveys occur in Puget Sound aboard a variety of small boats, with year-round sampling totaling 25 DAS. Survey effort involves commercial bottom trawls (twelve tows per year at greater than 10 m depth and for ten minutes), hook and line (twenty trips per year with up to twelve barbless hooks in the water at once), and bottom longline (180-m mainline deployed to approximately 60 m depth). The latter involves three sets per year with thirty 16/0 circle hooks per set.

14.

Puget Sound Marine Pelagic Food Web

—These surveys occur in Puget Sound only about every five years from April to October aboard charter vessels and totaling thirty DAS when it occurs. The survey deploys a Kodiak surface trawl (3.1 x 6.1 m) for five hundred tows of ten minute duration and depths greater than 10 m.

15.

Skagit Bay Juvenile Salmon Survey

—This survey occurs in Puget Sound aboard chartered vessels annually from April to September for thirty DAS and uses the same Kodiak surface trawl with the same protocols as the Puget Sound marine pelagic food web survey (180 tows per year).

16.

Elwha Dam Removal

—This Puget Sound study of the effects of dam removal on nearshore fish species includes use of a beach seine (43 x 1.8 m). The survey is conducted monthly using a small vessel, totaling 20 DAS and up to 140 samples per year (less than ten minutes per sample). Separate studies (“Snohomish Juvenile Salmon Studies” [up to 200 sets annually during 50 DAS; conducted monthly and twice-monthly from February to September] and “Puget Sound Salmon Contaminant Study” [up to 100 sets annually during 30 DAS from May to July]) use similar beach seines in similar ways. Additional surveys in the Columbia River (“Estuary Tidal Habitats” [up to 100 sets annually during 25 DAS, quarterly to monthly] and “LCR Ecosystem Monitoring” [up to 200 sets annually during 16 DAS, monthly from February to December]) also use beach seines similarly.

17.

Rockfish Genetics

—Hook and line fishing gear is used to capture bottomfish for biological sampling. Conducted in Puget Sound aboard charter boats from April to November (35-41 DAS), this survey uses baited hooks or bottom jigs for approximately 750 hook-hours per year.

18.

Marine Fish Research Including Broodstock Collection, Sampling, and Tagging

—This research involves pelagic longline and hook and line survey effort conducted in Puget Sound aboard charter vessels for approximately 15 DAS with effort varying monthly. The gear specifications and effort are similar to those described previously (for pelagic longline and hook and line only) for marine fish broodstock collection in the California Current.

19.

Eulachon Arrival Timing

—This survey uses a modified Cobb midwater trawl net 26-m headrope; 12 x 12 m opening) in the Columbia River estuary and plume to determine the arrival timing and distribution of spawning eulachon. The survey is conducted from January to March (15 DAS) aboard NOAA vessels, with sixty trawls per year (fifteen-minute tow duration at 30-40 m depth).

20.

Pair Trawl Juvenile Salmon Survey

—This trawl survey is conducted in the Columbia River between approximately RM 40-50 from March to August (80 DAS) aboard small vessels. A surface pair trawl (wings 92 x 92 m; trawl body 9 m wide x 6 m deep x 18 m long) modified with an open codend (2.4 x 3 m opening) is towed near the surface for eight to fifteen hours per trawl, totaling 800-1,200 tow-hours per year. The trawl is outfitted with a flow-through Passive Integrated Transponder (PIT) tag detector to assess passage of tagged juvenile salmon.

21.

Benefits of Wetland Restoration to Juvenile Salmon

—This study, occurring throughout the LCRRA, uses purse seines (150 x 9 m), beach seines (46 x 1.8 m), and surface trawls (3 x 6 m opening) to study salmon habitat use. The surveys are typically conducted aboard small research vessels and/or skiffs, with purse seine effort occurring for 32 DAS bi-weekly from March to October (ninety sets per year; typically less than one hour set duration) and beach seines and surface trawls (fifteen minute tows) occurring quarterly from March to December. The latter portion is conducted for 16 DAS, at two sites per day with two to three hauls of each type per site.

22.

Migratory Behavior of Adult Salmon

—This LCRRA survey uses tangle nets to catch and tag fish. Tangle nets (180 x 12 m) are deployed from commercial fishing vessels for 32 DAS from spring to fall, with up to 75 sets per year deployed for 25-45 minutes each.

Description of Active Acoustic Sound Sources

—This section contains a brief technical background on sound, the characteristics of certain sound types, and on metrics used in this proposal

inasmuch as the information is relevant to NWFSC's specified activity and to a discussion of the potential effects of the specified activity on marine mammals found later in this document. We also describe the active acoustic devices used by NWFSC.

Sound travels in waves, the basic components of which are frequency, wavelength, velocity, and amplitude. Frequency is the number of pressure waves that pass by a reference point per unit of time and is measured in hertz (Hz) or cycles per second. Wavelength is the distance between two peaks or corresponding points of a sound wave (length of one cycle). Higher frequency sounds have shorter wavelengths than lower frequency sounds, and typically attenuate (decrease) more rapidly, except in certain cases in shallower water. Amplitude is the height of the sound pressure wave or the “loudness” of a sound and is typically described using the relative unit of the decibel (dB). A sound pressure level (SPL) in dB is described as the ratio between a measured pressure and a reference pressure (for underwater sound, this is 1 microPascal [μPa]), and is a logarithmic unit that accounts for large variations in amplitude; therefore, a relatively small change in dB corresponds to large changes in sound pressure. The source level (SL) represents the SPL referenced at a distance of 1 m from the source (referenced to 1 μPa), while the received level is the SPL at the listener's position (referenced to 1 μPa).

Root mean square (rms) is the quadratic mean sound pressure over the duration of an impulse. Rms is calculated by squaring all of the sound amplitudes, averaging the squares, and then taking the square root of the average (Urick, 1983). Rms accounts for both positive and negative values; squaring the pressures makes all values positive so that they may be accounted for in the summation of pressure levels (Hastings and Popper, 2005). This measurement is often used in the context of discussing behavioral effects, in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures.

Sound exposure level (SEL; represented as dB re 1 μPa

2

-s) represents the total energy contained within a pulse, and considers both intensity and duration of exposure. For a single pulse, the numerical value of the SEL measurement is usually 5-15 dB lower than the rms sound pressure in dB re 1 μPa, with the comparative difference between measurements of rms and SEL measurements often tending to decrease with increasing range (Greene, 1997; McCauley

et al.,

1998). Peak sound pressure is the maximum instantaneous sound pressure measurable in the water at a specified distance from the source, and is represented in the same units as the rms sound pressure. Another common metric is peak-to-peak sound pressure (p-p), which is the algebraic difference between the peak positive and peak negative sound pressures. Peak-to-peak pressure is typically approximately 6 dB higher than peak pressure (Southall

et al.,

2007).

When underwater objects vibrate or activity occurs, sound-pressure waves are created. These waves alternately compress and decompress the water as the sound wave travels. Underwater sound waves radiate in a manner similar to ripples on the surface of a pond and may be either directed in a beam or beams (as for the sources considered here) or may radiate in all directions (omnidirectional sources). The compressions and decompressions associated with sound waves are detected as changes in pressure by aquatic life and man-made sound receptors such as hydrophones.

Even in the absence of sound from the specified activity, the underwater environment is typically loud due to ambient sound. Ambient sound is defined as environmental background sound levels lacking a single source or point (Richardson

et al.,

1995), and the sound level of a region is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical (

e.g.,

wind and waves, earthquakes, ice, atmospheric sound), biological (

e.g.,

sounds produced by marine mammals, fish, and invertebrates), and anthropogenic (

e.g.,

vessels, dredging, construction) sound. A number of sources contribute to ambient sound, including the following (Richardson

et al.,

1995):

• Wind and waves: The complex interactions between wind and water surface, including processes such as breaking waves and wave-induced bubble oscillations and cavitation, are a main source of naturally occurring ambient sound for frequencies between 200 Hz and 50 kHz (Mitson, 1995). In general, ambient sound levels tend to increase with increasing wind speed and wave height. Surf sound becomes important near shore, with measurements collected at a distance of 8.5 km from shore showing an increase of 10 dB in the 100 to 700 Hz band during heavy surf conditions.

• Precipitation: Sound from rain and hail impacting the water surface can become an important component of total sound at frequencies above 500 Hz, and possibly down to 100 Hz during quiet times.

• Biological: Marine mammals can contribute significantly to ambient sound levels, as can some fish and snapping shrimp. The frequency band for biological contributions is from approximately 12 Hz to over 100 kHz.

• Anthropogenic: Sources of ambient sound related to human activity include transportation (surface vessels), dredging and construction, oil and gas drilling and production, seismic surveys, sonar, explosions, and ocean acoustic studies. Vessel noise typically dominates the total ambient sound for frequencies between 20 and 300 Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz and, if higher frequency sound levels are created, they attenuate rapidly. Sound from identifiable anthropogenic sources other than the activity of interest (

e.g.,

a passing vessel) is sometimes termed background sound, as opposed to ambient sound.

The sum of the various natural and anthropogenic sound sources at any given location and time—which comprise “ambient” or “background” sound—depends not only on the source levels (as determined by current weather conditions and levels of biological and human activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 dB from day to day (Richardson

et al.,

1995). The result is that, depending on the source type and its intensity, sound from the specified activity may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals. Details of source types are described in the following text.

Sounds are often considered to fall into one of two general types: Pulsed and non-pulsed (defined in the following). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing (

e.g.,

Ward, 1997 in Southall

et al.,

2007). Please see Southall

et al.

(2007) for an in-depth discussion of these concepts.

Pulsed sound sources (

e.g.,

explosions, gunshots, sonic booms,

impact pile driving) produce signals that are brief (typically considered to be less than one second), broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated events or repeated in some succession. Pulsed sounds are all characterized by a relatively rapid rise from ambient pressure to a maximal pressure value followed by a rapid decay period that may include a period of diminishing, oscillating maximal and minimal pressures, and generally have an increased capacity to induce physical injury as compared with sounds that lack these features.

Non-pulsed sounds can be tonal, narrowband, or broadband, brief or prolonged, and may be either continuous or non-continuous (ANSI, 1995; NIOSH, 1998). Some of these non-pulsed sounds can be transient signals of short duration but without the essential properties of pulses (

e.g.,

rapid rise time). Examples of non-pulsed sounds include those produced by vessels, aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems (such as those used by the U.S. Navy). The duration of such sounds, as received at a distance, can be greatly extended in a highly reverberant environment.

We use generic sound exposure thresholds (see Table 1) to determine when an activity that produces sound might result in impacts to a marine mammal such that a take by harassment might occur. These thresholds should be considered guidelines for estimating when harassment may occur (

i.e.,

when an animal is exposed to levels equal to or exceeding the relevant criterion) in specific contexts; however, useful contextual information that may inform our assessment of effects is typically lacking and we consider these thresholds as step functions. NMFS is currently revising these acoustic guidelines; for more information on that process, please visit

www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

NMFS has determined that the 160-dB threshold for impulsive sources is most appropriate for use in considering the potential effects of the NWFSC's activities.

Table 1—Current Acoustic Exposure Criteria

Criterion

Definition

Threshold

Level A harassment (underwater)

Injury (PTS—any level above that which is known to cause TTS)

180 dB (cetaceans)/190 dB (pinnipeds) (rms).

Level B harassment (underwater)

Behavioral disruption

160 dB (impulsive source)/120 dB (continuous source) (rms).

A wide range of active acoustic devices are used in NWFSC fisheries surveys for remotely sensing bathymetric, oceanographic, and biological features of the environment. Most of these sources involve relatively high frequency, directional, and brief repeated signals tuned to provide sufficient focus and resolution on specific objects. NWFSC also uses passive listening sensors (

i.e.,

remotely and passively detecting sound rather than producing it), which do not have the potential to impact marine mammals. NWFSC active acoustic sources include various echosounders (

e.g.,

multibeam systems), scientific sonar systems, positional sonars (

e.g.,

net sounders for determining trawl position), and environmental sensors (

e.g.,

current profilers).

Mid- and high-frequency underwater acoustic sources typically used for scientific purposes operate by creating an oscillatory overpressure through rapid vibration of a surface, using either electromagnetic forces or the piezoelectric effect of some materials. A vibratory source based on the piezoelectric effect is commonly referred to as a transducer. Transducers are usually designed to excite an acoustic wave of a specific frequency, often in a highly directive beam, with the directional capability increasing with operating frequency. The main parameter characterizing directivity is the beam width, defined as the angle subtended by diametrically opposite “half power” (−3 dB) points of the main lobe. For different transducers at a single operating frequency the beam width can vary from 180° (almost omnidirectional) to only a few degrees. Transducers are usually produced with either circular or rectangular active surfaces. For circular transducers, the beam width in the horizontal plane (assuming a downward pointing main beam) is equal in all directions, whereas rectangular transducers produce more complex beam patterns with variable beam width in the horizontal plane. Please see Zykov and Carr (2014) for further discussion of electromechanical sound sources.

The types of active sources employed in fisheries acoustic research and monitoring may be considered in two broad categories here, based largely on their respective operating frequency (

e.g.,

within or outside the known audible range of marine species) and other output characteristics (

e.g.,

signal duration, directivity). As described below, these operating characteristics result in differing potential for acoustic impacts on marine mammals.

Category 1 active fisheries acoustic sources include those with high output frequencies (>180 kHz) that are outside the known functional hearing capability of any marine mammal. Sounds that are above the functional hearing range of marine animals may be audible if sufficiently loud (

e.g.,

Møhl, 1968). However, the relative output levels of these sources mean that they would potentially be detectable to marine mammals at maximum distances of only a few meters, and are highly unlikely to be of sufficient intensity to result in behavioral harassment. These sources also generally have short duration signals and highly directional beam patterns, meaning that any individual marine mammal would be unlikely to even receive a signal that would almost certainly be inaudible.

We are aware of two recent studies (Deng

et al.,

2014; Hastie

et al.,

2014) demonstrating some behavioral reaction by marine mammals to acoustic signals at frequencies above 180 kHz. These studies generally indicate only that sub-harmonics could be detectable by certain species at distances up to several hundred meters. However, this detectability is in reference to ambient noise, not to NMFS' established 160 dB threshold for assessing the potential for incidental take for these sources. Source levels of the secondary peaks considered in these studies—those within the hearing range of some marine mammals—range from 135-166 dB, meaning that these sub-harmonics would either be below the threshold for behavioral harassment or would attenuate to such a level within a few meters. Beyond these important study details, these high-frequency (

i.e.,

Category 1) sources and any energy they may produce below the primary frequency that could be audible to marine mammals would be dominated by a few primary sources that are

operated near-continuously, and the potential range above threshold would be so small as to essentially discount them. Therefore, Category 1 sources are not expected to have any effect on marine mammals and are not considered further in this document.

Category 2 acoustic sources, which are present on most NWFSC fishery research vessels, include a variety of single, dual, and multi-beam echosounders (many with a variety of modes), sources used to determine the orientation of trawl nets, and several current profilers with lower output frequencies than Category 1 sources. Category 2 active acoustic sources have moderate to high output frequencies (10 to 180 kHz) that are generally within the functional hearing range of marine mammals and therefore have the potential to cause behavioral harassment. However, while likely potentially audible to certain species, these sources have generally short ping durations and are typically focused (highly directional) to serve their intended purpose of mapping specific objects, depths, or environmental features. These characteristics reduce the likelihood of an animal receiving or perceiving the signal. A number of these sources, particularly those with relatively lower output frequencies coupled with higher output levels can be operated in different output modes (

e.g.,

energy can be distributed among multiple output beams) that may lessen the likelihood of perception by and potential impact on marine mammals.

We now describe specific acoustic sources used by NWFSC. The acoustic system used during a particular survey is optimized for surveying under specific environmental conditions (

e.g.,

depth and bottom type). Lower frequencies of sound travel further in the water (

i.e.,

good range) but provide lower resolution (

i.e.,

are less precise). Pulse width and power may also be adjusted in the field to accommodate a variety of environmental conditions. Signals with a relatively long pulse width travel further and are received more clearly by the transducer (

i.e.,

good signal-to-noise ratio) but have a lower range resolution. Shorter pulses provide higher range resolution and can detect smaller and more closely spaced objects in the water. Similarly, higher power settings may decrease the utility of collected data. Power level is also adjusted according to bottom type, as some bottom types have a stronger return and require less power to produce data of sufficient quality. Power is typically set to the lowest level possible in order to receive a clear return with the best data. Survey vessels may be equipped with multiple acoustic systems; each system has different advantages that may be utilized depending on the specific survey area or purpose. In addition, many systems may be operated at one of two frequencies or at a range of frequencies. Characteristics of these sources are summarized in Table 2.

(1)

Multi-Frequency Narrow Beam Scientific Echosounders

—Echosounders and sonars work by transmitting acoustic pulses into the water that travel through the water column, reflect off the seafloor, and return to the receiver. Water depth is measured by multiplying the time elapsed by the speed of sound in water (assuming accurate sound speed measurement for the entire signal path), while the returning signal itself carries information allowing “visualization” of the seafloor. Multi-frequency split-beam sensors are deployed from NWFSC survey vessels to acoustically map the distributions and estimate the abundances and biomasses of many types of fish; characterize their biotic and abiotic environments; investigate ecological linkages; and gather information about their schooling behavior, migration patterns, and avoidance reactions to the survey vessel. The use of multiple frequencies allows coverage of a broad range of marine acoustic survey activity, ranging from studies of small plankton to large fish schools in a variety of environments from shallow coastal waters to deep ocean basins. Simultaneous use of several discrete echosounder frequencies facilitates accurate estimates of the size of individual fish, and can also be used for species identification based on differences in frequency-dependent acoustic backscattering between species. The NWFSC operates the Simrad EK60 system, which typically transmits and receives at four frequencies ranging from 38-200 kHz.

(2)

Multibeam Echosounder and Sonar

—Multibeam echosounders and sonars operate similarly to the devices described above. However, the use of multiple acoustic “beams” allows coverage of a greater area compared to single beam sonar. The sensor arrays for multibeam echosounders and sonars are usually mounted on the keel of the vessel and have the ability to look horizontally in the water column as well as straight down. Multibeam echosounders and sonars are used for mapping seafloor bathymetry, estimating fish biomass, characterizing fish schools, and studying fish behavior. The NWFSC operates the Simrad ME70 system, which is mounted to the hull of the research vessel and emits frequencies in the 70-120 kHz range.

(3)

Single-Frequency Omnidirectional Sonar

—These sources provide omnidirectional imaging around the source with different vertical beamwidths available, which results in differential transmitting beam patterns. The cylindrical multi-element transducer allows the omnidirectional sonar beam to be electronically tilted down to −90°, allowing automatic tracking of schools of fish within the entire water volume around the vessel. NWFSC operates the Simrad SX90 system.

(4)

Acoustic Doppler Current Profiler (ADCP)

—An ADCP is a type of sonar used for measuring water current velocities simultaneously at a range of depths. Whereas current depth profile measurements in the past required the use of long strings of current meters, the ADCP enables measurements of current velocities across an entire water column. The ADCP measures water currents with sound, using the Doppler effect. A sound wave has a higher frequency when it moves towards the sensor (blue shift) than when it moves away (red shift). The ADCP works by transmitting “pings” of sound at a constant frequency into the water. As the sound waves travel, they ricochet off particles suspended in the moving water, and reflect back to the instrument. Due to the Doppler effect, sound waves bounced back from a particle moving away from the profiler have a slightly lowered frequency when they return. Particles moving toward the instrument send back higher frequency waves. The difference in frequency between the waves the profiler sends out and the waves it receives is called the Doppler shift. The instrument uses this shift to calculate how fast the particle and the water around it are moving. Sound waves that hit particles far from the profiler take longer to come back than waves that strike close by. By measuring the time it takes for the waves to return to the sensor, and the Doppler shift, the profiler can measure current speed at many different depths with each series of pings.

An ADCP anchored to the seafloor can measure current speed not just at the bottom, but at equal intervals to the surface. An ADCP instrument may be anchored to the seafloor or can be mounted to a mooring or to the bottom of a boat. ADCPs that are moored need an anchor to keep them on the bottom, batteries, and a data logger. Vessel-mounted instruments need a vessel with power, a shipboard computer to receive the data, and a GPS navigation system so the ship's movements can be subtracted from the current velocity

data. ADCPs operate at frequencies between 75 and 300 kHz.

(5)

Net Monitoring Systems

—During trawling operations, a range of sensors may be used to assist with controlling and monitoring gear. Net sounders give information about the concentration of fish around the opening to the trawl, as well as the clearances around the opening and the bottom of the trawl; catch sensors give information about the rate at which the codend is filling; symmetry sensors give information about the optimal geometry of the trawls; and tension sensors give information about how much tension is in the warps and sweeps. NWFSC uses the Simrad ITI Catch Monitoring System, which allows monitoring of the exact position of the gear and of what is happening in and around the trawl, and the Simrad FS70 Third Wire Net Sonde, which allows monitoring of the trawl opening.

Table 2—Operating Characteristics of NWFSC Active Acoustic Sources

Active acoustic system

Operating

frequencies

(kHz)

Maximum source level

Single ping duration (ms) and repetition rate (Hz)

Orientation/directionality

Nominal beamwidth

Simrad EK60 narrow beam echosounder

38, 70, 120, 200

224 dB

1 ms at 1 Hz

Downward looking

11°.

Simrad ME70 multibeam echosounder

70-120

205 dB

2 ms at 1 Hz

Downward looking

140°.

Simrad SX90 omnidirectional multibeam sonar

70-120

206 dB

2 ms at 1 Hz

Downward omnidirectional

0°-90° tilt angle from vertical (average).

Teledyne RD Instruments ADCP, Ocean Surveyor

75

224 dB

External trigger

Downward looking (30° tilt)

40° × 100°.

Simrad ITI Trawl Monitoring System

27-33

<200 dB

0.05-0.5 Hz

Downward looking

40° × 100°.

Simrad FS70 trawl sonar

330

216

1 ms at 120 kHz

Third wire trawl sonar for monitoring net opening and fishing conditions

40°.

Proposed Mitigation

In order to issue an incidental take authorization under section 101(a)(5)(A) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to such activity, “and other means of effecting the least practicable adverse impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such species or stock for subsistence uses.” Note that taxonomic information for certain species mentioned in this section is provided in the following section (“Description of Marine Mammals in the Area of the Specified Activity”).

The NWFSC has invested significant time and effort in identifying technologies, practices, and equipment to minimize the impact of the proposed activities on marine mammal species and stocks and their habitat. These efforts have resulted in the consideration of many potential mitigation measures, including those the NWFSC has determined to be feasible and has implemented in recent years as a standard part of sampling protocols. These measures include the move-on rule mitigation protocol (also referred to in the preamble as the move-on rule), protected species visual watches and use of acoustic pingers on trawl gear, as well as use of a marine mammal excluder device (MMED) in Nordic 264 midwater trawls.

Development of Mitigation Measures

In survey year 2008 in the CCE, NMFS' SWFSC had dramatically more incidental takes of marine mammals in research gear, in terms of both interactions and animals captured, than in any other year. The SWFSC had previously conducted over a thousand midwater trawl survey tows over more than 25 years, with very few incidents of marine mammal interactions (Hewitt, 2009), but the number of incidental takes in 2008 exceeded the aggregate total over all preceding years. Following the first SWFSC survey cruise in April 2008, during which a number of marine mammals were captured in trawl gear, the SWFSC convened a workshop involving SWFSC staff with expertise in survey design and operations and marine mammal bycatch mitigation (Hewitt, 2009). Participants worked to determine appropriate mitigation measures and to consider changes to sampling protocols in an effort to reduce marine mammal interactions.

The SWFSC also allocated resources towards the design, construction, and testing of a MMED that could be incorporated into the Nordic 264 trawl net, use of which had resulted in a large portion of takes. In 2009, the MMED was tested and use of the device added to SWFSC standard survey protocol for the Nordic 264 net (Dotson

et al.,

2010).

These efforts resulted in the consideration of many potential mitigation measures for all NMFS Science Centers, including those the NWFSC has determined to be feasible and relevant to their operations. These measures include the move-on rule, protected species visual watches and use of acoustic pingers on certain trawl gear, as well as use of the MMED in Nordic 264 trawls.

General Measures

Coordination and communication

—When NWFSC survey effort is conducted aboard NOAA-owned vessels, there are both vessel officers and crew and a scientific party. Vessel officers and crew are not composed of NWFSC staff, but are employees of NOAA's Office of Marine and Aviation Operations (OMAO), which is responsible for the management and operation of NOAA fleet ships and aircraft and is composed of uniformed officers of the NOAA Commissioned Corps as well as civilians. The ship's officers and crew provide mission support and assistance to embarked scientists, and the vessel's Commanding Officer (CO) has ultimate responsibility for vessel and passenger safety and, therefore, decision authority. When NWFSC survey effort is conducted aboard cooperative platforms (

i.e.,

non-NOAA vessels), ultimate responsibility and decision authority again rests with non-NWFSC personnel (

i.e.,

vessel's master or captain). Decision authority includes the implementation of mitigation measures (

e.g.,

whether to stop deployment of trawl gear upon observation of marine mammals). The scientific party involved in any NWFSC survey effort is composed, in part or whole, of NWFSC staff and is led by a Chief Scientist (CS). Therefore, because the NWFSC—not OMAO or any other entity that may have authority over survey platforms used by NWFSC—is the applicant to whom any incidental take authorization issued under the authority of these proposed regulations would be issued, we require that the NWFSC take all necessary measures to

coordinate and communicate in advance of each specific survey with OMAO, or other relevant parties, to ensure that all mitigation measures and monitoring requirements described herein, as well as the specific manner of implementation and relevant event-contingent decision-making processes, are clearly understood and agreed-upon. This may involve description of all required measures when submitting cruise instructions to OMAO or when completing contracts with external entities. NWFSC will coordinate and conduct briefings at the outset of each survey and as necessary between ship's crew (CO/master or designee(s), as appropriate) and scientific party in order to explain responsibilities, communication procedures, marine mammal monitoring protocol, and operational procedures. The CS will be responsible for coordination with the Officer on Deck (OOD; or equivalent on non-NOAA platforms) to ensure that requirements, procedures, and decision-making processes are understood and properly implemented.

Vessel speed

—Vessel speed during active sampling rarely exceeds 5 kn, with typical speeds being 2-4 kn. Transit speeds vary from 6-14 kn but average 10 kn. These low vessel speeds minimize the potential for ship strike (see “Potential Effects of the Specified Activity on Marine Mammals and Their Habitat” for an in-depth discussion of ship strike). At any time during a survey or in transit, if a crew member standing watch or dedicated marine mammal observer sights marine mammals that may intersect with the vessel course that individual will immediately communicate the presence of marine mammals to the bridge for appropriate course alteration or speed reduction, as possible, to avoid incidental collisions.

Other gears

—The NWFSC deploys a wide variety of gear to sample the marine environment during all of their research cruises. Many of these types of gear (

e.g.,

plankton nets, video camera and ROV deployments) are not considered to pose any risk to marine mammals and are therefore not subject to specific mitigation measures. However, at all times when the NWFSC is conducting survey operations at sea, the OOD and/or CS and crew will monitor for any unusual circumstances that may arise at a sampling site and use best professional judgment to avoid any potential risks to marine mammals during use of all research equipment.

Handling procedures

—The NWFSC will implement a number of handling protocols to minimize potential harm to marine mammals that are incidentally taken during the course of fisheries research activities. In general, protocols have already been prepared for use on commercial fishing vessels. Because incidental take of marine mammals in fishing gear is similar for commercial fisheries and research surveys, NWFSC proposes to adopt these protocols, which are expected to increase post-release survival. In general, following a “common sense” approach to handling captured or entangled marine mammals will present the best chance of minimizing injury to the animal and of decreasing risks to scientists and vessel crew. Handling or disentangling marine mammals carries inherent safety risks, and using best professional judgment and ensuring human safety is paramount.

Captured live or injured marine mammals are released from research gear and returned to the water as soon as possible with no gear or as little gear remaining on the animal as possible. Animals are released without removing them from the water if possible and data collection is conducted in such a manner as not to delay release of the animal(s) or endanger the crew. NWFSC staff will be instructed on how to identify different species; handle and bring marine mammals aboard a vessel; assess the level of consciousness; remove fishing gear; and return marine mammals to water.

Trawl Survey Visual Monitoring and Operational Protocols

Specific mitigation protocols are required for all trawl operations conducted by the NWFSC using Nordic 264 surface trawl gear, midwater trawl gear (modified Cobb, Aleutian Wing, and various commercial nets), and bottom trawl gear (double-rigged shrimp, Poly Nor'easter, modified Aberdeen, beam, and various commercial nets). Separate protocols (described below) are in place for the Kodiak surface trawl and pair trawl gear. Marine mammal watches will be conducted for at least ten minutes prior to the beginning of the planned set and throughout the tow and net retrieval, by scanning the surrounding waters with the naked eye and rangefinding binoculars (or monocular). Lookouts immediately alert the OOD and CS as to their best estimate of the species and number of animals observed and any observed animal's distance, bearing, and direction of travel relative to the ship's position. The CS must confirm with the OOD that no marine mammals have been seen within 500 m (or as far as may be observed if less than 500 m) of the ship or appear to be approaching the ship during the pre-set watch period prior to the deployment of any trawl gear. During nighttime operations, visual observation may be conducted using the naked eye and available vessel lighting but effectiveness is limited. The visual observation period typically occurs during transit leading up to arrival at the sampling station, rather than upon arrival on station. However, in some cases it may be necessary to conduct a plankton tow or other small net cast prior to deploying trawl gear. In these cases, the visual watch will continue until trawl gear is ready to be deployed. Aside from pre-trawl monitoring, the OOD/CS and crew standing watch will visually scan for marine mammals during all daytime operations.

It is important to note that the 500 m distance is provided only as a frame of reference for marine mammal observations that would nominally be of greater concern as regards the potential for interaction with research fishing gear. The primary concern is to avoid all marine mammal interactions (regardless of the numbers of takes proposed for authorization here), and the most appropriate course of action to achieve this goal in any given instance is likely to be related more to event-specific elements than to an arbitrary distance from the vessel. Depending on unpredictable contextual elements, animals sighted at distances greater than 500 m could provoke mitigation action or, conversely, animals sighted at closer range could be determined to not be at risk of interacting with research fishing gear. The NWFSC considers 500 m to be the average effective observation distance, but the actual effective range is determined by numerous factors related to the weather, ship observations, and the species observed.

The primary purpose of conducting pre-trawl visual monitoring is to implement the move-on rule. If marine mammals are sighted within 500 m (or as far as may be observed if less than 500 m) of the vessel and are considered at risk of interacting with the vessel or research gear, or appear to be approaching the vessel and are considered at risk of interaction, NWFSC may elect to either remain onsite to see if the animals move off or may move on to another sampling location. When remaining onsite, the set is delayed (typically for at least ten minutes) and, if the animals depart or appear to no longer be at risk of interacting with the vessel or gear, a further ten minute observation period is conducted. If no further observations are made or the animals still do not appear to be at risk of interaction, then the set may be made. If the vessel is moved to a different section of the sampling area,

move-on rule mitigation protocols would begin anew. If, after moving on, marine mammals remain at risk of interaction, the CS or watch leader may decide to move again or to skip the station. Marine mammals that are sighted further than 500 m from the vessel would be monitored to determine their position and movement in relation to the vessel. If they appear to be closing on the vessel, the move-on rule protocols may be implemented even if they are initially further than 500 m from the vessel.

For surface trawl surveys (

i.e.,

those surveys deploying the Nordic 264 net), which have historically presented the greatest risk of marine mammal interaction, dedicated crew are assigned to marine mammal monitoring duty (

i.e.,

have no other tasks) and care is taken to provide some rest periods for observers to avoid fatigue. At least two pairs of binoculars are available for verification of potential sightings. As the vessel approaches the station, the OOD and at least one assigned member of the scientific party monitor for marine mammals. Within several minutes of arriving on station and finishing their sampling duties, two additional members of the scientific party are assigned to monitor for marine mammals and, for the remainder of the tow, there would be a minimum of three members of the scientific party watching for marine mammals. Depending on the situational context (

e.g.,

numbers of marine mammals seen during the station approach or expected at that particular place and season), additional crew may be assigned to stand watch as necessary to provide full monitoring coverage around the vessel. Up to eight observers in total (including ship's crew standing watch) may be on duty during active trawling. The focus on the full area around the ship continues until trawl retrieval begins, at which point observational focus turns to the stern and the trawl net itself.

For midwater and bottom trawl surveys, the pre-set watch period is conducted by the OOD and bridge crew and typically occurs during transit prior to arrival at the sampling station, but may also include time on station if other types of gear or equipment (

e.g.,

bongo nets) are deployed before the trawl. For these trawls, risk of interaction during the tow is lower and monitoring effort is reduced to the bridge crew until trawl retrieval.

For all surveys, although the minimum pre-set watch period is ten minutes, the actual monitoring period is typically longer. During standard trawl operations, at least some of the trackline to be towed is typically traversed prior to setting gear in order to check for hazards. On surface trawl surveys, CTD casts and plankton/bongo net hauls are made prior to setting the trawl. These activities can take 25-35 minutes after the vessel arrives on station, depending on water depth, and monitoring for marine mammals continues throughout these activities. Midwater trawls and bottom trawls do not typically deploy other gears before deploying trawl gear but reconnaissance of the trackline often takes ten to fifteen minutes after arriving on station. In addition, once the decision is made to deploy the trawl gear, monitoring continues while the net is unspooled, which may take about ten minutes. Before the trawl doors are deployed, the net floats closed on the surface behind the vessel, and appropriate actions can be taken if marine mammals are sighted near the ship. Therefore, the marine mammal monitoring period—which begins before the vessel arrives on station and extends continuously through gear deployment—typically extends for over thirty minutes for all trawl types.

The effectiveness of visual monitoring may be limited depending on weather and lighting conditions. The OOD, CS or watch leader will determine the best strategy to avoid potential takes of marine mammals based on the species encountered and their numbers and behavior, position, and vector relative to the vessel, as well as any other factors. For example, a whale transiting through the sampling area in the distance may only require a short move from the designated station, whereas a pod of dolphins in close proximity to the vessel may require a longer move from the station or possibly cancellation of the planned tow if the group follows the vessel.

In general, trawl operations will be conducted immediately upon arrival on station (and on conclusion of the pre-watch period) in order to minimize the time during which marine mammals (particularly pinnipeds) may become attracted to the vessel. However, in some cases it will be necessary to conduct small net tows (

e.g.,

bongo net) prior to deploying trawl gear.

Once the trawl net is in the water, the OOD, CS, and/or crew standing watch will continue to visually monitor the surrounding waters and will maintain a lookout for marine mammal presence as far away as environmental conditions allow. If marine mammals are sighted before the gear is fully retrieved, the most appropriate response to avoid marine mammal interaction will be determined by the professional judgment of the CS, watch leader, OOD and other experienced crew as necessary. This judgment will be based on past experience operating trawl gears around marine mammals (

i.e.,

best professional judgment) and on NWFSC training sessions that will facilitate dissemination of expertise operating in these situations (

e.g.,

factors that contribute to marine mammal gear interactions and those that aid in successfully avoiding such events). Best professional judgment takes into consideration the species, numbers, and behavior of the animals, the status of the trawl net operation (

e.g.,

net opening, depth, and distance from the stern), the time it would take to retrieve the net, and safety considerations for changing speed or course. We recognize that it is not possible to dictate in advance the exact course of action that the OOD or CS should take in any given event involving the presence of marine mammals in proximity to an ongoing trawl tow, given the sheer number of potential variables, combinations of variables that may determine the appropriate course of action, and the need to consider human safety in the operation of fishing gear at sea. Nevertheless, we require a full accounting of factors that shape both successful and unsuccessful decisions, and these details will be fed back into NWFSC training efforts and ultimately help to refine the best professional judgment that determines the course of action taken in any given scenario (see further discussion in “Proposed Monitoring and Reporting”).

If trawling operations have been suspended because of the presence of marine mammals, the vessel will resume trawl operations (when practicable) only when the animals are believed to have departed the area. This decision is at the discretion of the OOD/CS and is dependent on the situation.

Standard survey protocols that are expected to lessen the likelihood of marine mammal interactions include standardized tow durations and distances. Standard tow durations of not more than thirty minutes at the target depth will typically be implemented, excluding deployment and retrieval time (which may require an additional thirty minutes, depending on target depth), to reduce the likelihood of attracting and incidentally taking marine mammals. Short tow durations decrease the opportunity for marine mammals to find the vessel and investigate. Trawl tow distances will be less than 3 nm—typically 1-2 nm, depending on the specific survey and trawl speed—which is expected to reduce the likelihood of attracting and incidentally taking marine mammals. In addition, care will be taken when

emptying the trawl to avoid damage to marine mammals that may be caught in the gear but are not visible upon retrieval. The gear will be emptied as quickly as possible after retrieval in order to determine whether or not marine mammals are present. The vessel's crew will clean trawl nets prior to deployment to remove prey items that might attract marine mammals. Catch volumes are typically small with every attempt made to collect all organisms caught in the trawl.

Marine mammal excluder device

—Excluder devices are specialized modifications, typically used in trawl nets, which are designed to reduce bycatch by allowing non-target taxa to escape the net. These devices generally consist of a grid of bars fitted into the net that allow target species to pass through the bars into the codend while larger, unwanted taxa (

e.g.,

turtles, sharks, mammals) strike the bars and are ejected through an opening in the net. Marine turtle bycatch in the commercial shrimp trawl industry led to the development of turtle excluder devices (TED) (

e.g.,

Mitchell

et al.,

1995) in the 1970s. TEDs are perhaps the most commonly used excluder devices, but devices designed specifically for the exclusion of marine mammals have also been developed for various fisheries around the world where marine mammal interactions are problematic (

e.g.,

Gibson and Isakssen, 1998; Northridge, 2003).

Similar to TEDs, MMEDs generally consist of a large aluminum grate positioned in the intermediate portion of the net forward of the codend and below an escape opening constructed into the upper net panel above the grate. These devices enable target species to pass through a grid or mesh barrier and into the codend while preventing the passage of marine mammals, which are ejected out through an escape opening or swim back out of the mouth of the net. The angled aluminum grate is intended to guide marine mammals through the escape opening. For full details of design and testing of the MMED designed by the SWFSC for the Nordic 264 net, please see Dotson

et al.

(2010).

MMEDs have not been proven to be fully effective at preventing marine mammal capture in trawl nets (

e.g.,

Chilvers, 2008) and are not expected to prevent marine mammal capture in NWFSC trawl surveys. It is difficult to effectively test such devices, in terms of effectiveness in excluding marine mammals as opposed to effects on target species catchability, because realistic field trials would necessarily involve marine mammal interactions with trawl nets. Use of artificial surrogates in field trials has not been shown to be a realistic substitute (Gibson and Isakssen, 1998). Nevertheless, we believe it reasonable to assume that use of MMEDs may reduce the likelihood of a given marine mammal interaction with trawl gear resulting in mortality. We do not infer causality, but note that annual marine mammal interactions with the Nordic 264 trawl net have been much reduced for the SWFSC (relative to 2008) since use of the MMED began.

Multiple types of midwater trawl nets are used in NWFSC trawl surveys. The Nordic 264 trawl net, used as a surface trawl by NWFSC, is generally much larger than the midwater trawls, is fished at faster speeds, and has a different shape and functionality than these nets. Very few marine mammal interactions with NWFSC pelagic trawl gear have involved nets other than the Nordic 264 (one of 37 total incidents since 1999; Table 4). Therefore, MMED use is not proposed for nets other than the Nordic 264.

The NWFSC has tested the MMED design used by the SWFSC and found that it caused a significant loss of some salmon species that were the target of their research. More recent experiments have used video cameras attached to the net opening and near the excluder device to test different configurations of the excluder device to minimize loss of target species. The experiments have looked at adding weight and stiffeners to the flap covering the escape hatch to keep it closed and flipping the MMED so the escape hatch faces down rather than up. Based on preliminary results, this downward-pointing escape hatch appears to be the best design for minimizing loss of target species. Additional research will be necessary to calibrate catch levels in tows with the excluder device compared to past tows that did not contain the excluder (

i.e.,

to align the new catchability rates with historical data sets). During these configuration and calibration experiments some nets will be fished without the MMED in order to provide controls for catchability. Once the NWFSC completes these experiments the MMED will be used in all future trawls with the Nordic 264. Please see “Proposed Monitoring and Reporting” for additional discussion.

Acoustic deterrent devices

—Acoustic deterrent devices (pingers) are underwater sound-emitting devices that have been shown to decrease the probability of interactions with certain species of marine mammals when fishing gear is fitted with the devices. Multiple studies have reported large decreases in harbor porpoise mortality (approximately eighty to ninety percent) in bottom-set gillnets (nets composed of vertical panes of netting, typically set in a straight line and either anchored to the bottom or drifting) during controlled experiments (

e.g.,

Kraus

et al.,

1997; Trippel

et al.,

1999; Gearin

et al.,

2000). Using commercial fisheries data rather than a controlled experiment, Palka

et al.

(2008) reported that harbor porpoise bycatch rates in the northeast U.S gillnet fishery when fishing without pingers was about two to three times higher compared to when pingers were used. After conducting a controlled experiment in a California drift gillnet fishery during 1996-97, Barlow and Cameron (2003) reported significantly lower bycatch rates when pingers were used for all cetacean species combined, all pinniped species combined, and specifically for short-beaked common dolphins (85 percent reduction) and California sea lions (69 percent reduction). While not a statistically significant result, catches of Pacific white-sided dolphins (which are historically one of the most frequently captured species in NWFSC surveys; see Table 4) were reduced by seventy percent. Carretta

et al.

(2008) subsequently examined nine years of observer data from the same drift gillnet fishery and found that pinger use had eliminated beaked whale bycatch. Carretta and Barlow (2011) assessed the long-term effectiveness of pingers in reducing marine mammal bycatch in the California drift gillnet fishery by evaluating fishery data from 1990-2009 (with pingers in use beginning in 1996), finding that bycatch rates of cetaceans were reduced nearly fifty percent in sets using a sufficient number of pingers. However, in contrast to the findings of Barlow and Cameron (2003), they report no significant difference in pinniped bycatch.

To be effective, a pinger must emit a signal that is sufficiently aversive to deter the species of concern, which requires that the signal is perceived while also deterring investigation. In rare cases, aversion may be learned as a warning when an animal has survived interaction with gear fitted with pingers (Dawson, 1994). The mechanisms by which pingers work in operational settings are not fully understood, but field trials and captive studies have shown that sounds produced by pingers are aversive to harbor porpoises (

e.g.,

Laake

et al.,

1998; Kastelein

et al.,

2000; Culik

et al.,

2001), and it is assumed that when marine mammals are deterred from interacting with gear fitted with pingers that it is because the sounds produced by the devices are aversive.

Two primary concerns expressed with regard to pinger effectiveness in reducing marine mammal bycatch relate to habituation (

i.e.,

marine mammals may become habituated to the sounds made by the pingers, resulting in increasing bycatch rates over time; Dawson, 1994; Cox

et al.,

2001; Carlström

et al.,

2009) and the “dinner bell effect” (Dawson, 1994; Richardson

et al.,

1995), which implies that certain predatory marine mammal species (

e.g.,

sea lions) may come to associate pingers with a food source (

e.g.,

fish caught in nets) with the result that bycatch rates may be higher in nets with pingers than in those without.

Palka

et al.

(2008) report that habituation has not occurred on a level that affects the bycatch estimate for the northeast U.S. gillnet fishery, while cautioning that the data studied do not provide a direct method to study habituation. Similarly, Carretta and Barlow (2011) report that habituation is not apparent in the California drift gillnet fishery, with the proportion of pinger-fitted sets with bycatch not significantly different for either cetaceans or pinnipeds between the periods 1996-2001 and 2001-09; in fact, bycatch rates for both taxa overall were lower in the latter period. We are not aware of any long-term behavioral studies investigating habituation. Bycatch rates of California sea lions, specifically, did increase during the latter period. However, the authors do not attribute the increase to pinger use (

i.e.,

the “dinner bell effect”); rather, they believe that continuing increases in population abundance for the species (Carretta

et al.,

2015a) coincident with a decline in fishery effort are responsible for the increased rate of capture. Despite these potential limitations on the effectiveness of pingers, and while effectiveness has not been tested on trawl gear, we believe that the available evidence supports an assumption that use of pingers is likely to reduce the potential for marine mammal interactions with NWFSC trawl gear.

If one assumes that use of a pinger is effective in deterring marine mammals from interacting with fishing gear, one must therefore assume that receipt of the acoustic signal has a disturbance effect on those marine mammals (

i.e.,

Level B harassment). However, Level B harassment that may be incurred as a result of NWFSC use of pingers does not constitute take that must be authorized under the MMPA. The MMPA prohibits the taking of marine mammals by U.S. citizens or within the U.S. EEZ unless such taking is appropriately permitted or authorized. However, the MMPA provides several narrowly defined exemptions from this requirement (

e.g.,

for Alaskan natives; for defense of self or others; for Good Samaritans [16 U.S.C. 1371(b)-(d)]). Section 109(h) of the MMPA (16 U.S.C. 1379(h)) allows for the taking of marine mammals in a humane manner by federal, state, or local government officials or employees in the course of their official duties if the taking is necessary for “the protection or welfare of the mammal,” “the protection of the public health and welfare,” or “the non-lethal removal of nuisance animals.” NWFSC use of pingers as a deterrent device, which may cause Level B harassment of marine mammals, is intended solely for the avoidance of potential marine mammal interactions with NWFSC research gear (

i.e.,

avoidance of Level A harassment, serious injury, or mortality). Therefore, use of such deterrent devices, and the taking that may result, is for the protection and welfare of the mammal and is covered explicitly under MMPA section 109(h)(1)(A). Potential taking of marine mammals resulting from NWFSC use of pingers is not discussed further in this document.

Pingers will be deployed during all surface trawl operations (

i.e.,

using the Nordic 264 net), with two pairs of pingers installed near the net opening. The vessel's crew will ensure that pingers are operational prior to deployment. Pinger brands typically used by NWFSC include the Aquatec Subsea Limited model AQUAmark and Fumunda Marine models F10 and F70, with the following attributes: (1) Operational depth of 10-200 m; (2) tones range from 200-400 ms in duration, repeated every five to six seconds; (3) variable frequency of 10-160 kHz; and (4) maximum source level of 145 dB rms re 1 μPa. Please see “Marine Mammal Hearing” below for reference to functional and best hearing ranges for marine mammals present in the CCE.

Kodiak surface trawl and pair trawl gear

—The Kodiak surface trawl, used only in Puget Sound, has only limited potential for marine mammal interaction. This gear type is a small net towed at slow speeds (about 2 kn) as close to shore as the net can be fished, and these characteristics mean that marine mammals would likely be able to avoid the net or swim out of it if necessary. However, rules for cetaceans would be similar as for other net types (

i.e.,

delay and/or move-on if cetaceans observed within approximately 500 m or clearly approaching from greater distance). If killer whales are observed at any distance, the net would not be deployed and the move-on rule invoked.

The pair trawl is used only in the Columbia River, and is fished with an open codend. Although unlikely, there is some potential for pinnipeds to become entangled in the net material. NWFSC's practice, which would be allowed under section 109(h) of the MMPA, is to deter pinnipeds from encountering the net using pyrotechnic devices and other measures. Therefore, separate mitigation is not warranted, and we do not discuss NWFSC deterrence of pinnipeds associated with pair trawl surveys further in this document. Please see the NWFSC's draft Programmatic Environmental Assessment for further information about this practice.

Longline and Other Hook and Line Survey Visual Monitoring and Operational Protocols

Visual monitoring requirements for all longline surveys are similar to the general protocols described above for trawl surveys. Please see that section for full details of the visual monitoring protocol and the move-on rule mitigation protocol. In summary, requirements for longline surveys are to: (1) Conduct visual monitoring during the thirty-minute period prior to arrival on station; (2) implement the move-on rule if marine mammals are observed within the area around the vessel and maybe at risk of interacting with the vessel or gear; (3) deploy gear as soon as possible upon arrival on station (depending on presence of marine mammals); and (4) maintain visual monitoring effort throughout deployment and retrieval of the longline gear. As was described for trawl gear, the OOD, CS, or watch leader will use best professional judgment to minimize the risk to marine mammals from potential gear interactions during deployment and retrieval of gear. If marine mammals are detected during setting operations and are considered to be at risk, immediate retrieval or suspension of operations may be warranted. If operations have been suspended because of the presence of marine mammals, the vessel will resume setting (when practicable) only when the animals are believed to have departed the area. If marine mammals are detected during retrieval operations and are considered to be at risk, haul-back may be postponed. These decisions are at the discretion of the OOD/CS and are dependent on the situation. If killer whales are observed at any distance, the set would not occur and the move-on rule would be invoked.

Other types of hook and line surveys (

e.g.,

rod and reel) generally use the same protocols as longline surveys.

However, for hook and line surveys in Puget Sound the move-on rule is not required for pinnipeds because they are commonly abundant on shore nearby hook and line sampling locations. Use of the move-on rule in these circumstances would represent an impracticable impact on NWFSC survey operations, and we note that no marine mammals have ever been captured in NWFSC hook and line surveys (Table 4). However, the NWFSC would implement the move-on rule for hook and line surveys in Puget Sound for any cetaceans that are within 500 m and may be at risk of interaction with the survey operation. If killer whales are observed at any distance, fishing would not occur.

As for trawl surveys, some standard survey protocols are expected to minimize the potential for marine mammal interactions. Soak times are typically short relative to commercial fishing operations, measured from the time the last hook is in the water to when the first hook is brought out of the water. NWFSC longline protocols specifically prohibit chumming (releasing additional bait to attract target species to the gear) and spent bait and offal is retained on the vessel until all gear has been retrieved. Some hook and line surveys use barbless hooks, which are less likely to injure a hooked animal.

Seine Survey Visual Monitoring and Operational Protocols

Visual monitoring and operational protocols for seine surveys are similar to those described previously for trawl surveys, with a focus on visual observation in the survey area and avoidance of marine mammals that may be at risk of interaction with survey vessels or gear. For purse seine operations, visual monitoring is focused on avoidance of cetaceans and aggregations of pinnipeds. Individual or small numbers of pinnipeds may be attracted to purse seine operations, especially in Puget Sound, and are frequently observed to enter operational purse seines to depredate the catch and exit the net unharmed. Use of the move-on rule in these circumstances would represent an impracticable impact on NWFSC survey operations, and we note that no marine mammals have ever been captured in NWFSC seine surveys (Table 4).

If pinnipeds are in the immediate vicinity of a purse seine survey, the set may be delayed until animals move away or the move-on rule is determined to be appropriate, but the net would not be opened if already deployed and pinnipeds enter it. However, delay would not be invoked if only few pinnipeds are present (

e.g.,

less than five), and they do not appear to obviously be at risk.

If any dolphins or porpoises are observed within approximately 500 m of the purse seine survey location, the set would be delayed. If any dolphins or porpoises are observed in the net, the net would be immediately opened to free the animals. If killer whales or other large whales are observed at any distance the net would not be set, and the move-on rule would be invoked.

Beach seines are typically set nearshore by small boat crews, who visually survey the area prior to the set. The set would not be made within 200 m of any hauled pinnipeds. Otherwise, marine mammals are unlikely to be at risk of interaction with NWFSC beach seine operations, as the nets are relatively small and deployed and retrieved slowly. If a marine mammal is observed attempting to interact with the beach seine gear, the gear would immediately be lifted and removed from the water.

Tangle net protocols

—Tangle nets are used only in the Columbia River. NWFSC attempts to avoid pinnipeds by rotating sampling locations on a daily basis and by avoiding fishing near haulout areas. However, as was described for NWFSC use of pair trawl gear in the LCRRA, NWFSC also deters pinnipeds from interacting with tangle net gear as necessary using pyrotechnic devices and visual presence, a practice allowed under section 109(h) of the MMPA. Therefore, we do not discuss NWFSC deterrence of pinnipeds associated with tangle net surveys further in this document. Please see the NWFSC's draft Programmatic Environmental Assessment for further information about this practice. If pinniped presence in the vicinity of tangle net surveys is so abundant as to be uncontrollable through deterrence, sampling would be discontinued for a given day.

We have carefully evaluated the NWFSC's proposed mitigation measures and considered a range of other measures in the context of ensuring that we prescribed the means of effecting the least practicable adverse impact on the affected marine mammal species and stocks and their habitat. Our evaluation of potential measures included consideration of the following factors in relation to one another: (1) The manner in which, and the degree to which, the successful implementation of the measure is expected to minimize adverse impacts to marine mammals, (2) the proven or likely efficacy of the specific measure to minimize adverse impacts as planned; and (3) the practicability of the measure for applicant implementation.

Any mitigation measure(s) we prescribe should be able to accomplish, have a reasonable likelihood of accomplishing (based on current science), or contribute to the accomplishment of one or more of the general goals listed below:

(1) Avoidance or minimization of injury or death of marine mammals wherever possible (goals 2, 3, and 4 may contribute to this goal).

(2) A reduction in the number (total number or number at biologically important time or location) of individual marine mammals exposed to stimuli expected to result in incidental take (this goal may contribute to 1, above, or to reducing takes by behavioral harassment only).

(3) A reduction in the number (total number or number at a biologically important time or location) of times any individual marine mammal would be exposed to stimuli expected to result in incidental take (this goal may contribute to 1, above, or to reducing takes by behavioral harassment only).

(4) A reduction in the intensity of exposure to stimuli expected to result in incidental take (this goal may contribute to 1, above, or to reducing the severity of behavioral harassment only).

(5) Avoidance or minimization of adverse effects to marine mammal habitat, paying particular attention to the prey base, blockage or limitation of passage to or from biologically important areas, permanent destruction of habitat, or temporary disturbance of habitat during a biologically important time.

(6) For monitoring directly related to mitigation, an increase in the probability of detecting marine mammals, thus allowing for more effective implementation of the mitigation.

Based on our evaluation of the NWFSC's proposed measures, as well as other measures we considered, we have preliminarily determined that the proposed mitigation measures provide the means of effecting the least practicable adverse impact on marine mammal species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance.

Description of Marine Mammals in the Area of the Specified Activity

We have reviewed NWFSC's species descriptions—which summarize available information regarding status and trends, distribution and habitat preferences, behavior and life history, and auditory capabilities of the

potentially affected species—for accuracy and completeness and refer the reader to Sections 3 and 4 of NWFSC's application, as well as to NMFS' Stock Assessment Reports (SARs;

www.nmfs.noaa.gov/pr/sars/

), instead of reprinting the information here. Table 3 lists all species with expected potential for occurrence in the specified geographical region where NWFSC proposes to conduct the specified activity and summarize information related to the population or stock, including potential biological removal (PBR). For taxonomy, we follow Committee on Taxonomy (2015). PBR, defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population, is discussed in greater detail later in this document (see “Negligible Impact Analyses”). Species that could potentially occur in the proposed research areas but are not expected to have the potential for interaction with NWFSC research gear or that are not likely to be harassed by NWFSC's use of active acoustic devices are described briefly but omitted from further analysis. These include extralimital species, which are species that do not normally occur in a given area but for which there are one or more occurrence records that are considered beyond the normal range of the species. For status of species, we provide information regarding U.S. regulatory status under the MMPA and ESA.

Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study area. NMFS' stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. Survey abundance (as compared to stock or species abundance) is the total number of individuals estimated within the survey area, which may or may not align completely with a stock's geographic range as defined in the SARs. These surveys may also extend beyond U.S. waters.

Thirty-four species (with 43 managed stocks) are considered to have the potential to co-occur with NWFSC activities. Extralimital species or stocks in the California Current include the Bryde's whale (

Balaenoptera edeni brydei

) and the North Pacific right whale (

Eubalaena japonica

). In addition, the sea otter is found in coastal waters, with the southern sea otter (

Enhydra lutris nereis

) found in California and the northern (or eastern) sea otter (

E. l. kenyoni;

Washington stock only) found in Washington. However, sea otters are managed by the U.S. Fish and Wildlife Service and are not considered further in this document. All stocks are assessed in NMFS' U.S. Pacific SARs (Carretta

et al.,

2015a,b), with the exception of the west coast transient and northern resident stocks of killer whales, the eastern North Pacific stock of the northern fur seal, and the eastern stock of the Steller sea lion, which are considered in the U.S. Alaska SARs (Allen and Angliss, 2015; Muto and Angliss, 2015). Values presented in Table 3 reflect the most recent information available (

i.e.,

final 2014 and draft 2015 reports, as appropriate).

Two populations of gray whales are recognized, eastern and western North Pacific (ENP and WNP). WNP whales are known to feed in the Okhotsk Sea and off of Kamchatka before migrating south to poorly known wintering grounds, possibly in the South China Sea. The two populations have historically been considered geographically isolated from each other; however, recent data from satellite-tracked whales indicate that there is some overlap between the stocks. Two WNP whales were tracked from Russian foraging areas along the Pacific rim to Baja California (Mate

et al.,

2011), and, in one case where the satellite tag remained attached to the whale for a longer period, a WNP whale was tracked from Russia to Mexico and back again (IWC, 2012). Between 22-24 WNP whales are known to have occurred in the eastern Pacific through comparisons of ENP and WNP photo-identification catalogs (IWC, 2012; Weller

et al.,

2011; Burdin

et al.,

2011), and WNP animals comprised 8.1 percent of gray whales identified during a recent field season off of Vancouver Island (Weller

et al.,

2012). In addition, two genetic matches of WNP whales have been recorded off of Santa Barbara, CA (Lang

et al.,

2011). More recently, Urban

et al.

(2013) compared catalogs of photo-identified individuals from Mexico with photographs of whales off Russia and reported a total of 21 matches. Therefore, a portion of the WNP population is assumed to migrate, at least in some years, to the eastern Pacific during the winter breeding season.

However, the NWFSC does not believe that any gray whale (WNP or ENP) would be likely to interact with its research gear, as it is extremely unlikely that a gray whale in close proximity to NWFSC research activity would be one of the approximately twenty WNP whales that have been documented in the eastern Pacific. The likelihood that a WNP whale would interact with NWFSC research gear is insignificant and discountable, and WNP gray whales are omitted from further analysis.

Table 3—Marine Mammals Potentially Present in the Vicinity of NWFSC Research Activities

Common name

Scientific name

Stock

Occurrence

CC

LCR

PS

ESA/MMPA

status;

strategic

(Y/N)

1

Stock abundance

(CV, N

min

, most recent abundance

survey)

2

PBR

Annual M/SI

3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)

Family Eschrichtiidae

Gray whale

Eschrichtius robustus

Eastern North Pacific

X

X

-; N

20,990 (0.05; 20,125; 2011)

624

132

Family Balaenopteridae (rorquals)

Humpback whale

Megaptera novaeangliae kuzira

California/Oregon/Washington (CA/OR/WA)

X

X

E/D; Y

1,918 (0.03; 1,855; 2011)

12

11

≥5.5

Minke whale

Balaenoptera acutorostrata scammoni

CA/OR/WA

X

X

-; N

478 (1.36; 202; 2008)

2

0

Sei whale

B. borealis borealis

Eastern North Pacific

X

E/D; Y

126 (0.53; 83; 2008)

0.17

0

Fin whale

B. physalus physalus

CA/OR/WA

X

E/D; Y

3,051 (0.18; 2,598; 2008)

16

2.2

Blue whale

B. musculus musculus

Eastern North Pacific

X

E/D; Y

1,647 (0.07; 1,551; 2011)

12

2.3

0.9

Superfamily Odontoceti (toothed whales, dolphins, and porpoises)

Family Physeteridae

Sperm whale

Physeter macrocephalus

CA/OR/WA

X

E/D; Y

2,106 (0.58; 1,332; 2008)

2.7

1.7

Family Kogiidae

Pygmy sperm whale

Kogia breviceps

CA/OR/WA

X

-; N

579 (1.02; 271; 2008)

2.7

0

Dwarf sperm whale

K. sima

CA/OR/WA

5

X

-; N

Unknown

Undet.

0

Family Ziphiidae (beaked whales)

Cuvier's beaked whale

Ziphius cavirostris

CA/OR/WA

X

-; Y

6,590 (0.55; 4,481; 2008)

45

0

Baird's beaked whale

Berardius bairdii

CA/OR/WA

X

-; N

847 (0.81; 466; 2008)

4.7

0

Hubbs' beaked whale

Mesoplodon carlhubbsi

CA/OR/WA

6

X

-; Y

694 (0.65; 389; 2008)

3.9

0

Blainville's beaked whale

M. densirostris

X

Ginkgo-toothed beaked whale

M. ginkgodens

X

Perrin's beaked whale

M. perrini

X

Lesser (pygmy) beaked whale

M. peruvianus

X

Stejneger's beaked whale

M. stejnegeri

X

Family Delphinidae

Common bottlenose dolphin

Tursiops truncatus truncatus

CA/OR/WA Offshore

X

-; N

1,006 (0.48; 684; 2008)

5.5

≥2

California Coastal

X

-; N

323 (0.13; 290; 2005)

2.4

0.2

Striped dolphin

Stenella coeruleoalba

CA/OR/WA

X

-; N

10,908 (0.34; 8,231; 2008)

82

0

Long-beaked common dolphin

Delphinus capensis capensis

California

X

-; N

107,016 (0.42; 76,224; 2009)

610

13.8

Short-beaked common dolphin

D. delphis delphis

CA/OR/WA

X

-; N

411,211 (0.21; 343,990; 2008)

3,440

64

Pacific white-sided dolphin

Lagenorhynchus obliquidens

CA/OR/WA

X

X

-; N

26,930 (0.28; 21,406; 2008)

171

17.8

Northern right whale dolphin

Lissodelphis borealis

CA/OR/WA

X

-; N

8,334 (0.4; 6,019; 2008)

48

4.8

Risso's dolphin

Grampus griseus

CA/OR/WA

X

-; N

6,272 (0.3; 4,913; 2008)

39

1.6

Killer whale

Orcinus orca

4

West Coast Transient

7

X

X

X

-; N

243 (n/a; 2009)

2.4

0

Eastern North Pacific Offshore

X

-; N

240 (0.49; 162; 2008)

1.6

0

Eastern North Pacific Southern Resident

X

X

E/D; Y

78

10

(n/a; 2014)

0.14

0

Eastern North Pacific Northern Resident

X

X

-; N

261 (n/a; 2011)

1.96

0

Short-finned pilot whale

Globicephala macrorhynchus

CA/OR/WA

X

-; N

760 (0.64; 465; 2008)

4.6

0

Family Phocoenidae (porpoises)

Harbor porpoise

Phocoena phocoena vomerina

Morro Bay

X

-; N

2,917 (0.41; 2,102; 2012)

21

≥0.6

Monterey Bay

X

-; N

3,715 (0.51; 2,480; 2011)

25

0

San Francisco-Russian River

X

-; N

9,886 (0.51; 6,625; 2011)

66

0

Northern CA/Southern OR

X

-; N

35,769 (0.52; 23,749; 2011)

475

≥0.6

Northern OR/WA Coast

X

X

-; N

21,487 (0.44; 15,123; 2011)

151

≥3

Washington Inland Waters

X

-; N

10,682 (0.38; 7,841; 2003)

63

≥2.2

Dall's porpoise

Phocoenoides dalli dalli

CA/OR/WA

X

X

X

-; N

42,000 (0.33; 32,106; 2008)

257

≥0.4

Order Carnivora—Superfamily Pinnipedia

Family Otariidae (eared seals and sea lions)

Guadalupe fur seal

Arctocephalus philippii townsendi

X

T/D; Y

7,408 (n/a; 3,028; 1993)

91

13

0

Northern fur seal

Callorhinus ursinus

Pribilof Islands/Eastern Pacific

X

D; Y

648,534 (0.2; 548,919; 2012)

11,802

439

California

X

-; N

14,050

10

(n/a; 7,524; 2013)

451

1.8

California sea lion

Zalophus californianus

United States

X

X

X

-; N

296,750 (n/a; 153,337; 2011)

9,200

389

Steller sea lion

Eumetopias jubatus monteriensis

Eastern U.S.

9

X

X

X

D; Y

60,131-74,448 (n/a; 36,551; 2013)

11

1,645

92.3

Family Phocidae (earless seals)

Harbor seal

Phoca vitulina richardii

California

X

-; N

30,968 (n/a; 27,348; 2012)

1,641

43

OR/WA Coast

8

X

X

-; N

24,732 (0.12; 22,380; 1999)

Undet.

10.6

Washington Northern Inland Waters.

8

X

-; N

11,036 (0.15; 7,213; 1999)

Undet.

9.8

Southern Puget Sound

8

X

-; N

1,568 (0.15; 1,025; 1999)

Undet.

3.4

Hood Canal

8

X

-; N

1,088 (0.15; 711; 1999)

Undet.

0.2

Northern elephant seal

Mirounga angustirostris

California Breeding

X

X

-; N

179,000 (n/a; 81,368; 2010)

4,882

8.8

1

Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (−) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.

2

NMFS marine mammal stock assessment reports at:

www.nmfs.noaa.gov/pr/sars/.

CV is coefficient of variation; N

min

is the minimum estimate of stock abundance. In some cases, CV is not applicable. For three stocks of killer whales, the abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction factor derived from knowledge of the species' (or similar species') life history to arrive at a best abundance estimate; therefore, there is no associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore.

3

These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (

e.g.,

commercial fisheries, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented in the draft 2015 SARs (Carretta

et al.,

2015b; Muto and Angliss, 2015).

4

Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2015).

5

No information is available to estimate the population size of dwarf sperm whales off the U.S. west coast, as no sightings of this species have been documented despite numerous vessel surveys of this region (Carretta

et al.,

2015a). Dwarf and pygmy sperm whales are difficult to differentiate at sea but, based on previous sighting surveys and historical stranding data, it is thought that recent ship survey sightings were of pygmy sperm whales.

6

The six species of Mesoplodont beaked whales occurring in the CCE are managed as a single stock due to the rarity of records and the difficulty in distinguishing these animals to species in the field. Based on bycatch and stranding records, it appears that

M. carlhubbsi

is the most commonly encountered of these species (Carretta

et al.,

2008; Moore and Barlow, 2013). Additional managed stocks in the Pacific include

M. stejnegeri

in Alaskan waters and

M. densirostris

in Hawaiian waters.

7

The abundance estimate for this stock includes only animals from the “inner coast” population occurring in inside waters of southeastern Alaska, British Columbia, and Washington—excluding animals from the “outer coast” subpopulation, including animals from California—and therefore should be considered a minimum count. For comparison, the previous abundance estimate for this stock, including counts of animals from California that are now considered outdated, was 354.

8

Abundance estimates for these stocks are not considered current. PBR is therefore considered undetermined for these stocks, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available information for use in this document.

9

The eastern distinct population segment of the Steller sea lion, previously listed as threatened, was delisted under the ESA on December 4, 2013 (78 FR 66140; November 4, 2013).

10

These are provisional abundance estimates presented in the draft 2015 SARs.

11

Best abundance is calculated as the product of pup counts and a factor based on the birth rate, sex and age structure, and growth rate of the population. A range is presented because the extrapolation factor varies depending on the vital rate parameter resulting in the growth rate (

i.e.,

high fecundity or low juvenile mortality).

12

These stocks are known to spend a portion of their time outside the U.S. EEZ. Therefore, the PBR presented here is the allocation for U.S. waters only and is a portion of the total. The total PBR for blue whales is 9.3 (one-quarter allocation for U.S. waters), and the total for humpback whales is 22 (one half allocation for U.S. waters). Annual M/SI presented for these species is for U.S. waters only.

13

This represents annual M/SI in U.S. waters. However, the vast majority of M/SI for this stock—the level of which is unknown—would likely occur in Mexican waters.

Take reduction planning

—Take reduction plans are designed to help recover and prevent the depletion of strategic marine mammal stocks that interact with certain U.S. commercial fisheries, as required by Section 118 of the MMPA. The immediate goal of a take reduction plan is to reduce, within six months of its implementation, the M/SI of marine mammals incidental to commercial fishing to less than the PBR level. The long-term goal is to reduce, within five years of its implementation, the M/SI of marine mammals incidental to commercial fishing to insignificant levels, approaching a zero serious injury and mortality rate, taking into account the economics of the fishery, the availability of existing technology, and existing state or regional fishery management plans. Take reduction teams are convened to develop these plans.

For marine mammals in the California Current Ecosystem, there is currently one take reduction plan in effect (Pacific Offshore Cetacean Take Reduction Plan). The goal of this plan is to reduce M/SI of several marine mammal stocks incidental to the California thresher shark/swordfish drift gillnet fishery (CA DGN). A team was convened in 1996 and a final plan produced in 1997 (62 FR 51805; October 3, 1997). Marine mammal stocks of concern initially included the California, Oregon, and Washington stocks for all CCE beaked whales, short-finned pilot whales, pygmy sperm whales, sperm whales, and humpback whales. The most recent five-year averages of M/SI for these stocks are below PBR, and none of these species were taken in the fishery in 2012-13. More information is available on the Internet at:

www.nmfs.noaa.gov/pr/interactions/trt/poctrp.htm.

Of the stocks of concern, the NWFSC has requested the authorization of

incidental M/SI + Level A for the short-finned pilot whale only (see “Estimated Take by Incidental Harassment” later in this document). The most recent reported average annual human-caused mortality for short-finned pilot whales (2004-08) is zero animals. The NWFSC does not use drift gillnets in its fisheries research program; therefore, take reduction measures applicable to the CA DGN fisheries are not relevant to the NWFSC.

Unusual Mortality Events (UME)

—A UME is defined under the MMPA as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.” From 1991 to the present, there have been sixteen formally recognized UMEs on the U.S. west coast involving species under NMFS' jurisdiction. The most recent of these, and the only ones involving currently ongoing investigations, involve Guadalupe fur seals and California sea lions. Increased strandings of Guadalupe fur seals (eight times the historical average) have occurred along the entire coast of California. These increased strandings were reported beginning in January 2015 and peaked from April through June 2015. Findings from the majority of stranded animals include malnutrition with secondary bacterial and parasitic infections. Beginning in January 2013, elevated strandings of California sea lion pups were observed in southern California, with live sea lion strandings nearly three times higher than the historical average. Findings to date indicate that a likely contributor to the large number of stranded, malnourished pups was a change in the availability of sea lion prey for nursing mothers, especially sardines. These UMEs are occurring in the same areas and the causes and mechanisms of this remain under investigation (

www.nmfs.noaa.gov/pr/health/mmume/guadalupefurseals2015.html; www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm;

accessed December 3, 2015).

Additional UMEs in the past ten years include those involving harbor porpoises in California (2008; cause determined to be ecological factors); Guadalupe fur seals in the Northwest (2007; undetermined); large whales in California (2007; human interaction); cetaceans in California (2007; undetermined); and harbor porpoises in the Pacific Northwest (2006; undetermined). There is also an ongoing UME in the western Gulf of Alaska that involves elevated large whale mortalities and may be affecting eastern North Pacific gray whales, which also occur in the NWFSC's research areas. For more information on UMEs, please visit the Internet at:

www.nmfs.noaa.gov/pr/health/mmume/events.html.

Potential Effects of the Specified Activity on Marine Mammals and Their Habitat

This section includes a summary and discussion of the ways that components of the specified activity (

e.g.,

gear deployment, use of active acoustic sources, visual disturbance) may impact marine mammals and their habitat. The “Estimated Take by Incidental Harassment” section later in this document will include a quantitative analysis of the number of individuals that are expected to be taken by this activity. The “Negligible Impact Analysis” section will include an analysis of how this specific activity will impact marine mammals and will consider the content of this section, the “Estimated Take by Incidental Harassment” section, and the “Proposed Mitigation” section, to draw conclusions regarding the likely impacts of this activity on the reproductive success or survivorship of individuals and from that on the affected marine mammal populations or stocks. In the following discussion, we consider potential effects to marine mammals from ship strike, physical interaction with the gear types described previously, use of active acoustic sources, and visual disturbance of pinnipeds.

Ship Strike

Vessel collisions with marine mammals, or ship strikes, can result in death or serious injury of the animal. Wounds resulting from ship strike may include massive trauma, hemorrhaging, broken bones, or propeller lacerations (Knowlton and Kraus, 2001). An animal at the surface may be struck directly by a vessel, a surfacing animal may hit the bottom of a vessel, or an animal just below the surface may be cut by a vessel's propeller. More superficial strikes may not kill or result in the death of the animal. These interactions are typically associated with large whales (

e.g.,

fin whales), which are occasionally found draped across the bulbous bow of large commercial ships upon arrival in port. Although smaller cetaceans or pinnipeds are more maneuverable in relation to large vessels than are large whales, they may also be susceptible to strike. The severity of injuries typically depends on the size and speed of the vessel, with the probability of death or serious injury increasing as vessel speed increases (Knowlton and Kraus, 2001; Laist

et al.,

2001; Vanderlaan and Taggart, 2007; Conn and Silber, 2013). Impact forces increase with speed, as does the probability of a strike at a given distance (Silber

et al.,

2010; Gende

et al.,

2011).

Pace and Silber (2005) found that the probability of death or serious injury increased rapidly with increasing vessel speed. Specifically, the predicted probability of serious injury or death increased from 45 to 75 percent as vessel speed increased from 10 to 14 kn, and exceeded ninety percent at 17 kn. Higher speeds during collisions result in greater force of impact, but higher speeds also appear to increase the chance of severe injuries or death through increased likelihood of collision by pulling whales toward the vessel (Clyne, 1999; Knowlton

et al.,

1995). In a separate study, Vanderlaan and Taggart (2007) analyzed the probability of lethal mortality of large whales at a given speed, showing that the greatest rate of change in the probability of a lethal injury to a large whale as a function of vessel speed occurs between 8.6 and 15 kn. The chances of a lethal injury decline from approximately eighty percent at 15 kn to approximately twenty percent at 8.6 kn. At speeds below 11.8 kn, the chances of lethal injury drop below fifty percent, while the probability asymptotically increases toward one hundred percent above 15 kn.

In an effort to reduce the number and severity of strikes of the endangered North Atlantic right whale (

Eubalaena glacialis

), NMFS implemented speed restrictions in 2008 (73 FR 60173; October 10, 2008). These restrictions require that vessels greater than or equal to 65 ft (19.8 m) in length travel at less than or equal to 10 kn near key port entrances and in certain areas of right whale aggregation along the U.S. eastern seaboard. Conn and Silber (2013) estimated that these restrictions reduced total ship strike mortality risk levels by eighty to ninety percent.

For vessels used in NWFSC research activities, transit speeds average 10 kn (but vary from 6-14 kn), while vessel speed during active sampling is typically only 2-4 kn. At sampling speeds, both the possibility of striking a marine mammal and the possibility of a strike resulting in serious injury or mortality are discountable. At average transit speed, the probability of serious injury or mortality resulting from a strike is less than fifty percent. However, the likelihood of a strike actually happening is again discountable. Ship strikes, as analyzed in the studies cited above, generally involve commercial shipping, which is

much more common in both space and time than is research activity. Jensen and Silber (2004) summarized ship strikes of large whales worldwide from 1975-2003 and found that most collisions occurred in the open ocean and involved large vessels (

e.g.,

commercial shipping). Commercial fishing vessels were responsible for three percent of recorded collisions, while only one such incident (0.75 percent) was reported for a research vessel during that time period.

It is possible for ship strikes to occur while traveling at slow speeds. For example, a NOAA-chartered survey vessel traveling at low speed (5.5 kn) while conducting multi-beam mapping surveys off the central California coast struck and killed a blue whale in 2009. The State of California determined that the whale had suddenly and unexpectedly surfaced beneath the hull, with the result that the propeller severed the whale's vertebrae, and that this was an unavoidable event. This strike represents the only such incident in approximately 540,000 hours of similar coastal mapping activity (

p

= 1.9 × 10

−6

; 95% CI = 0-5.5 × 10

−6

; NMFS, 2013). In addition, a research vessel reported a fatal strike in 2011 of a dolphin in the Atlantic, demonstrating that it is possible for strikes involving smaller cetaceans or pinnipeds to occur. In that case, the incident report indicated that an animal apparently was struck by the vessel's propeller as it was intentionally swimming near the vessel. While indicative of the type of unusual events that cannot be ruled out, neither of these instances represents a circumstance that would be considered reasonably foreseeable or that would be considered preventable.

In summary, we anticipate that vessel collisions involving NWFSC research vessels, while not impossible, represent unlikely, unpredictable events for which there are no preventive measures. No ship strikes have been reported from any fisheries research activities conducted or funded by the NWFSC in any of the three research areas. Given the relatively slow speeds of research vessels, the presence of bridge crew watching for obstacles at all times (including marine mammals), the presence of marine mammal observers on some surveys, and the small number of research cruises, we believe that the possibility of ship strike is discountable and, further, that were a strike of a large whale to occur, it would be unlikely to result in serious injury or mortality. No incidental take resulting from ship strike is anticipated, and this potential effect of research will not be discussed further in the following analysis.

Research Gear

The types of research gear used by NWFSC were described previously under “Detailed Description of Activity.” Here, we broadly categorize these gears into those whose use we consider to have an extremely unlikely potential to result in marine mammal interaction and those whose use we believe may result in marine mammal interaction. Gears in the former category are not considered further, while those in the latter category are carried forward for further analysis. Gears with likely potential for marine mammal interaction include trawls, longlines and other hook and line gear, seines (primarily purse seines), and tangle nets.

Trawl nets, longlines, and purse seines deployed by NWFSC are similar to gear used in various commercial fisheries, and the potential for and history of marine mammal interaction with these gears through physical contact (

i.e.,

capture or entanglement) is well-documented. Read

et al.

(2006) estimated marine mammal bycatch in U.S. fisheries from 1990-99 and derived an estimate of global marine mammal bycatch by expanding U.S. bycatch estimates using data on fleet composition from the United Nations Food and Agriculture Organization (FAO). Although most U.S. bycatch for both cetaceans (84 percent) and pinnipeds (98 percent) occurred in gillnets (a gear type not generally used by NWFSC), global marine mammal bycatch in trawl nets and longlines is likely substantial given that total global bycatch is thought to number in the hundreds of thousands of individuals (Read

et al.,

2006). In addition, global bycatch via longline has likely increased, as longlines have become the most common method of capturing swordfish and tuna since the U.N. banned the use of high seas driftnets over 2.5 km long in 1991 (high seas driftnets were previously often 40-60 km long) (Read, 2008; FAO, 2001).

Marine mammals are widely regarded as being quite intelligent and inquisitive, and when their pursuit of prey coincides with human pursuit of the same resources, it should be expected that physical interaction with fishing gear may occur (

e.g.,

Beverton, 1985). Fishermen and marine mammals are both drawn to areas of high prey density, and certain fishing activities may further attract marine mammals by providing food (

e.g.,

bait, captured fish, bycatch discards) or by otherwise making it easier for animals to feed on a concentrated food source. Provision of foraging opportunities near the surface may present an advantage by negating the need for energetically expensive deep foraging dives (Hamer and Goldsworthy, 2006). Trawling, for example, can make available previously unexploited food resources by gathering prey that may otherwise be too fast or deep for normal predation, or may concentrate calories in an otherwise patchy landscape (Fertl and Leatherwood, 1997). Pilot whales, which are generally considered to be teuthophagous (

i.e.,

feeding primarily on squid), were commonly observed in association with Atlantic mackerel (

Scomber scombrus

) trawl fisheries from 1977-88 in the northeast U.S. EEZ (Waring

et al.,

1990). Not surprisingly, stomach contents of captured whales were observed to have high proportions of mackerel (68 percent of non-trace food items), indicating that the ready availability of a novel, concentrated, high-calorie prey item resulted in changed dietary composition (Read, 1994).

These interactions can result in injury or death for the animal(s) involved and/or damage to fishing gear. Coastal animals, including various pinnipeds, bottlenose dolphins, and harbor porpoises, are perhaps the most vulnerable to these interactions and set or passive fishing gear (

e.g.,

gillnets, traps) the most likely to be interacted with (

e.g.,

Beverton, 1985; Barlow

et al.,

1994; Read

et al.,

2006; Byrd

et al.,

2014; Lewison

et al.,

2014). Although interactions are less common for use of trawl nets and longlines (gear used by NWFSC), they do occur with sufficient frequency to necessitate the establishment of required mitigation measures for multiple U.S. fisheries using both types of gear (NMFS, 2014). It is likely that no species of marine mammal can be definitively excluded from the potential for interaction with fishing gear (

e.g.,

Northridge, 1984); however, the extent of interactions is likely dependent on the biology, ecology, and behavior of the species involved and the type, location, and nature of the fishery.

Trawl nets

—As described previously, trawl nets are towed nets (

i.e.,

active fishing) consisting of a cone-shaped net with a codend or bag for collecting the fish and can be designed to fish at the bottom, surface, or any other depth in the water column. Here we refer to bottom trawls and pelagic trawls (midwater or surface,

i.e.,

any net not designed to tend the bottom while fishing). Trawl nets in general have the potential to capture or entangle marine mammals, which have been known to be caught in bottom trawls, presumably when feeding on fish caught therein,

and in pelagic trawls, which may or may not be coincident with their feeding (Northridge, 1984).

Capture or entanglement may occur whenever marine mammals are swimming near the gear, intentionally (

e.g.,

foraging) or unintentionally (

e.g.,

migrating), and any animal captured in a net is at significant risk of drowning unless quickly freed. Animals can also be captured or entangled in netting or tow lines (also called lazy lines) other than the main body of the net; animals may become entangled around the head, body, flukes, pectoral fins, or dorsal fin. Interaction that does not result in the immediate death of the animal by drowning can cause injury (

i.e.,

Level A harassment) or serious injury. Constricting lines wrapped around the animal can immobilize the animal or injure by cutting into or through blubber, muscles and bone (

i.e.,

penetrating injuries) or constricting blood flow to or severing appendages. Immobilization of the animal, if it does not result in immediate drowning, can cause internal injuries from prolonged stress and/or severe struggling and/or impede the animal's ability to feed (resulting in starvation or reduced fitness) (Andersen

et al.,

2008).

Marine mammal interactions with trawl nets, through capture or entanglement, are well-documented. Dolphins are known to attend operating nets in order to either benefit from disturbance of the bottom or to prey on discards or fish within the net. For example, Leatherwood (1975) reported that the most frequently observed feeding pattern for bottlenose dolphins in the Gulf of Mexico involved herds following working shrimp trawlers, apparently feeding on organisms stirred up from the benthos. Bearzi and di Sciara (1997) opportunistically investigated working trawlers in the Adriatic Sea from 1990-94 and found that ten percent were accompanied by foraging bottlenose dolphins. However, pelagic trawls have greater potential to capture cetaceans, because the nets may be towed at faster speeds, these trawls are more likely to target species that are important prey for marine mammals (

e.g.,

squid, mackerel), and the likelihood of working in deeper waters means that a more diverse assemblage of species could potentially be present (Hall

et al.,

2000).

Globally, at least seventeen cetacean species are known to feed in association with trawlers and individuals of at least 25 species are documented to have been killed by trawl nets, including several large whales, porpoises, and a variety of delphinids (Perez, 2006; Young and Iudicello, 2007; Karpouzli and Leaper, 2004; Hall

et al.,

2000; Fertl and Leatherwood, 1997; Northridge, 1991; Song

et al.,

2010). At least eighteen species of seals and sea lions are known to have been killed in trawl nets (Wickens, 1995; Perez, 2006; Zeeberg

et al.,

2006). Generally, direct interaction between trawl nets and marine mammals (both cetaceans and pinnipeds) has been recorded wherever trawling and animals co-occur. A lack of recorded interactions where animals are known to be present may indicate simply that trawling is absent or an insignificant component of fisheries in that region or that interactions were not observed, recorded, or reported.

In evaluating risk relative to a specific fishery (or comparable research survey), one must consider the size of the net as well as frequency, timing, and location of deployment. These considerations inform determinations of whether interaction with marine mammals is likely. Of the net types described previously under “Trawl Nets,” NWFSC has recorded marine mammal interactions primarily with the Nordic 264 surface trawl net but also has one recorded interaction with the modified Cobb midwater trawl. No marine mammal interactions have been recorded for any bottom trawl survey.

Longlines

—Longlines are basically strings of baited hooks that are either anchored to the bottom, for targeting groundfish, or are free-floating, for targeting pelagic species and represent a passive fishing technique. Pelagic longlines, which notionally fish near the surface with the use of floats, may be deployed in such a way as to fish at different depths in the water column. For example, deep-set longlines targeting tuna may have a target depth of 400 m, while a shallow-set longline targeting swordfish is set at 30-90 m depth. We refer here to bottom and pelagic longlines. Any longline generally consists of a mainline from which leader lines (gangions) with baited hooks branch off at a specified interval, and is left to passively fish, or soak, for a set period of time before the vessel returns to retrieve the gear. Longlines are marked by two or more floats that act as visual markers and may also carry radio beacons; aids to detection are of particular importance for pelagic longlines, which may drift a significant distance from the deployment location. Pelagic longlines are generally composed of various diameter monofilament line and are generally much longer, and with more hooks, than are bottom longlines. Bottom longlines may be of monofilament or multifilament natural or synthetic lines.

Marine mammals may be hooked or entangled in longline gear, with interactions potentially resulting in death due to drowning, strangulation, severing of carotid arteries or the esophagus, infection, an inability to evade predators, or starvation due to an inability to catch prey (Hofmeyr

et al.,

2002), although it is more likely that animals will survive being hooked if they are able to reach the surface to breathe. Injuries, which may include serious injury, include lacerations and puncture wounds. Animals may attempt to depredate either bait or catch, with subsequent hooking, or may become accidentally entangled. As described for trawls, entanglement can lead to constricting lines wrapped around the animals and/or immobilization, and even if entangling materials are removed the wounds caused may continue to weaken the animal or allow further infection (Hofmeyr

et al.,

2002). Large whales may become entangled in a longline and then break free with a portion of gear trailing, resulting in alteration of swimming energetics due to drag and ultimate loss of fitness and potential mortality (Andersen

et al.,

2008). Weight of the gear can cause entangling lines to further constrict and further injure the animal. Hooking injuries and ingested gear are most common in small cetaceans and pinnipeds, but have been observed in large cetaceans (

e.g.,

sperm whales). The severity of the injury depends on the species, whether ingested gear includes hooks, whether the gear works its way into the gastrointestinal (GI) tract, whether the gear penetrates the GI lining, and the location of the hooking (

e.g.,

embedded in the animal's stomach or other internal body parts) (Andersen

et al.,

2008). Bottom longlines pose less of a threat to marine mammals due to their deployment on the ocean bottom but can still result in entanglement in buoy lines or hooking as the line is either deployed or retrieved. The rate of interaction between longline fisheries and marine mammals depends on the degree of overlap between longline effort and species distribution, hook style and size, type of bait and target catch, and fishing practices (such as setting/hauling during the day or at night).

As was noted for trawl nets, many species of cetaceans and pinnipeds are documented to have been killed by longlines, including several large whales, porpoises, a variety of delphinids, seals, and sea lions (Perez, 2006; Young and Iudicello, 2007; Northridge, 1984, 1991; Wickens, 1995). Generally, direct interaction between

longlines and marine mammals (both cetaceans and pinnipeds) has been recorded wherever longline fishing and animals co-occur. A lack of recorded interactions where animals are known to be present may indicate simply that longlining is absent or an insignificant component of fisheries in that region or that interactions were not observed, recorded, or reported. Hook and line (

e.g.,

rod and reel) gear also carries some lesser potential for marine mammal interaction, as the use of baited hooks in the presence of inquisitive marine mammals necessarily carries some risk. However, the scale of hook and line operations in relation to longline operations and the lack of extended, unattended soak times mean that use of other hook and line gea

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