# Endangered and Threatened Species; Notice of 12-Month Findings on a Petition To List the Tope Shark as Threatened or Endangered Under the Endangered Species Act and Proposed Listing of Two Distinct Population Segments of Tope Shark as Threatened

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2026-07294

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** April 15, 2026
- **Citation:** 91 FR 20260

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 223
[Docket No. 260410-0096; RTID 0648-XR121]
Endangered and Threatened Species; Notice of 12-Month Findings on a Petition To List the Tope Shark as Threatened or Endangered Under the Endangered Species Act and Proposed Listing of Two Distinct Population Segments of Tope Shark as Threatened

AGENCY:

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

ACTION:

Notice of 12-month petition findings; proposed rule and request for comments.

SUMMARY:

We, NMFS, have completed a comprehensive status review of the tope shark (
Galeorhinus galeus
) in response to a petition to list the species as threatened or endangered under the Endangered Species Act (ESA) of 1973. After reviewing the best scientific and commercial data available, we have determined that this species is comprised of six distinct population segments (DPSs) and that two, the Southern (So.) Africa and Southwest (SW) Atlantic DPSs, are likely to become in danger of extinction throughout all or a significant portion of their ranges in the foreseeable future. Therefore, we propose to list the So. Africa and SW Atlantic DPSs as threatened species under the ESA. We have also determined that the remaining four DPSs—the Northeast (NE) Atlantic, NE Pacific, SW Pacific, and Southeast (SE) Pacific DPSs—do not meet the definition of a threatened or endangered species under section 4(a) of the ESA and therefore do not warrant listing under the ESA. We solicit information to inform the final listing determinations.

DATES:

Comments on this proposed rule must be received by June 15, 2026. Public hearing requests must be made by June 1, 2026.

ADDRESSES:

A plain language summary of this proposed rule is available at
https://www.regulations.gov/docket/NOAA-NMFS-2022-0048.
You may submit comments on the proposed rule, identified by NOAA-NMFS-2022-0048 by the following method:

•
Electronic Submissions:
Submit all electronic comments via the Federal e-Rulemaking Portal. Go to
https://www.regulations.gov
and enter NOAA-NMFS-2022-0048 in the Search box. Click on the “Comment” icon, complete the required fields, and enter or attach your comments.

•
Mail:
Submit written comments to Adrienne Lohe, NMFS Office of Protected Resources, 1315 East-West Highway, Silver Spring, MD 20910.

Instructions:
Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on
https://www.regulations.gov
without change. All personal identifying information (
e.g.,
name and address), confidential business information, or otherwise sensitive information submitted voluntarily by the sender will be publicly accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if you wish to remain anonymous).

The petition, Status Review Report,
Federal Register
notices, and the list of references can be accessed electronically online at:
https://www.fisheries.noaa.gov/species/tope-shark/conservation-management.
The peer review report is available online at:
https://www.noaa.gov/organization/information-technology/peer-review-plans.

FOR FURTHER INFORMATION CONTACT:

Adrienne Lohe, NMFS Office of Protected Resources, 301-427-8442,
adrienne.lohe@noaa.gov,
or Lisa Manning, NMFS Office of Protected Resources, 301-427-8466,
lisa.manning@noaa.gov.

SUPPLEMENTARY INFORMATION:

Background

On February 15, 2022, we received a petition from the Center for Biological Diversity and the Defend Them All Foundation (Petitioners) to list the tope shark,
G. galeus,
as a threatened or endangered species under the ESA and to designate critical habitat concurrent with the listing. The petition asserts that
G. galeus
is threatened by four of the five ESA section 4(a)(1) factors: (1) present and threatened destruction, modification, or curtailment of its habitat or range; (2) overutilization for commercial and recreational purposes; (3) inadequacy of existing regulatory mechanisms; and (4) other natural or manmade factors. In addition to requesting that we analyze whether the tope shark warrants listing based on its status throughout all or a significant portion of its range, the petition requests that we analyze whether any distinct population segments (DPS) of tope shark warrant listing. The petition also requests that, if we determine the tope shark or any DPSs of tope shark warrant listing as a threatened species, we promulgate a protective regulation under section 4(d) of the ESA, and requests that we promulgate a regulation under section 4(e) of the ESA for species similar in appearance to the tope shark.

On April 28, 2022, we published a 90-day finding announcing that the petition presented substantial scientific or commercial information indicating that the petitioned action may be warranted (87 FR 25209). We also announced the initiation of a status review of the species, as required by section 4(b)(3)(A) of the ESA, and requested information to inform the agency's decision on whether this species warrants listing as endangered or threatened under the ESA. In response to this request, we received six public comments which expressed general support for listing the tope shark under the ESA without providing any supporting information.

Section 4(b)(3)(B) of the ESA requires that within 12 months of receiving a petition that is found to present substantial scientific or commercial information indicating that the petitioned action may be warranted, the Secretary shall make a finding on whether the petitioned action is warranted. On June 24, 2025, the Petitioners filed a complaint seeking a court-ordered deadline for issuing the 12-month finding; and pursuant to a court-approved settlement agreement, NMFS was required to submit this finding to the
Federal Register
by April 15, 2026.

Listing Determinations Under the ESA

We are responsible for determining whether species under NMFS' jurisdiction are threatened or endangered under the ESA (16 U.S.C. 1531
et seq.
). To make this determination, we first consider whether a group of organisms constitutes a “species,” which is defined in section 3 of the ESA to include “any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature” (16 U.S.C. 1532(16)). On February 7, 1996, NMFS and the U.S. Fish and Wildlife Service (FWS; together, the Services) adopted a policy describing what constitutes a DPS of a taxonomic species (“DPS Policy,” 61 FR 4722). The joint DPS Policy identifies two elements that must be considered when identifying a DPS: (1) the discreteness of the population

segment in relation to the remainder of the taxon to which it belongs; and (2) the significance of the population segment to the remainder of the taxon to which it belongs.

Section 3 of the ESA defines an endangered species as any species which is in danger of extinction throughout all or a significant portion of its range and a threatened species as any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range (16 U.S.C. 1532(6), 16 U.S.C. 1532(20)). Thus, an “endangered species” is one that is presently in danger of extinction. A “threatened species,” on the other hand, is not presently in danger of extinction, but is likely to become so in the foreseeable future (that is, at a later time).

Under section 4(a)(1) of the ESA, we must determine whether any species is endangered or threatened as a result of any one or a combination of any of the following factors: (A) the present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence (16 U.S.C. 1533(a)(1); 50 CFR 424.11(c)). We are also required to make listing determinations based solely on the best scientific and commercial data available, after conducting a review of the species' status and after taking into account efforts, if any, being made by any state or foreign nation (or subdivision thereof) to protect the species (16 U.S.C. 1533(b)(1)(A)). The status review (described in more detail below) and this determination are based on analyses and information that are fully consistent with the Gold Standard Science Executive Order (E.O. 14303) in that they are reproducible; transparent; communicative of error and uncertainty; collaborative and interdisciplinary; skeptical of findings and assumptions; structured for falsifiability of hypotheses; subject to unbiased peer review; accepting of negative results as positive outcomes; and without conflicts of interest.

Status Review

To determine whether the tope shark warrants listing under the ESA, a Status Review Report was completed (Manning, Rippe, and Lohe 2026), which summarizes information on the species' taxonomy, distribution, abundance, life history, ecology, and biology; identifies threats or stressors affecting the status of the species; and assesses the species' current and future extinction risk. We appointed three biologists in the Office of Protected Resources Endangered Species Conservation Division to compile and complete a scientific review of the best scientific and commercial data available on the tope shark. These biologists conducted an Extinction Risk Analysis to assess the threats affecting the tope shark, as well as demographic risk factors (abundance, productivity, spatial distribution, and diversity), using the information in the scientific review. The Status Review Report presents their assessment of the level of extinction risk facing the tope shark but makes no recommendation as to the listing status of the species.

The Status Review Report was subject to independent, unbiased peer review pursuant to the Office of Management and Budget Final Information Quality Bulletin for Peer Review (M-05-03; December 16, 2004). It was peer reviewed by seven independent specialists selected from the academic and scientific community with expertise in tope shark biology, conservation, or management. The peer reviewers were asked to evaluate the adequacy, appropriateness, and application of data used in the Status Review Report. All peer reviewer comments were addressed prior to finalizing the Status Review Report and publication of this finding.

We subsequently reviewed the Status Review Report, its cited references, and peer review comments, and concluded that it synthesizes the best available scientific and commercial information on the tope shark. In making our listing determinations, we have applied the statutory provisions of the ESA, including evaluation of the factors set forth in section 4(a)(1)(A)-(E), our regulations in 50 CFR 424 regarding listing determinations, and relevant policies identified herein.

The Status Review Report and the peer review report are available electronically (see
ADDRESSES
). Below is a summary of the information from the Status Review Report and our analysis of the status of the tope shark.

Biological Review

Taxonomy and Species Description

The tope shark,
G. galeus
(Linnaeus 1758), is a member of class Chondrichthyes, subclass Elasmobranchii (sharks and rays), order Carcharhiniformes (ground sharks), and family Triakidae (houndsharks) (ITIS and FishBase, accessed June 13, 2022). Once thought to each be distinct species, other nominal species, including
G. australis
(Macleay 1881),
Galeus canis
(Bonaparte 1841),
G. chilensis
(Pérez Canto 1886),
G. communis
(Owen 1853),
G. cyrano
(Whitley 1930),
G. linnei
(Malm 1877),
G. molinae
(Philippi 1887),
G. nilssoni
(Bonaparte 1846),
G. vitaminicu
s (de Buen 1950),
G. vulgaris
(Fleming 1828),
G. zyopterus
(Jordan and Gilbert 1883), are now considered synonyms of
G. galeus
(Compagno 1984; Fricke
et al.
2022). Available genetic data for
G. galeus
provide evidence of strong population structuring by major geographic regions, but there is currently no evidence supporting the identification of any subspecies (Chabot and Allen 2009; Chabot 2015; Chiaramonte
et al.
2016; Bester-van der Merwe
et al.
2017).

Other common names for this species have origins in the species' appearance, behavior, or common uses. It is often called soupfin shark in the United States and South Africa (also “vaalhaai” in South Africa), school shark or snapper shark in Australia and New Zealand, “cazón” (dogfish), “tiburón vitamínico” (vitamin shark), or “tiburón trompa de cristal” (glass-snouted shark) in Argentina and Uruguay, “tiburón aceitoso” (oily shark) or “sulfin” in Mexico, “çãcao-bico-de-cristal” (glass-snouted shark) in Brazil, “tollo” in Peru and Chile, and “requin-hâ” in French-speaking countries of the NE Atlantic (Walker 1999; Chiaramonte
et al.
2016; Walker
et al.
2020).

The tope shark is a medium-sized shark, generally reaching lengths of about 183 centimeters (cm) (6 feet). Maximum reported lengths vary by region, and range from a maximum total length (TL) of 155 cm for the southwestern Atlantic (Peres and Vooren 1991) to 200 cm TL in the Mediterranean Sea (Tunisian coast; Capapé and Mellinger 1988). The body is slender and gray or grayish brown dorsally and whitish ventrally, and young have black markings on their fins (Olsen 1984; Compagno
et al.
1989). The snout is long and pointed, with a wide, crescent-shaped mouth. The small, triangular shaped teeth are serrated on the outer edges (Olsen 1984; Compagno
et al.
1989). The large and horizontally oval eyes are positioned low on the sides of the head and have a nictitating membrane (external in juveniles and internal in adults and subadults), and the nostrils are positioned closer to the mouth and upper lip than to the tip of the snout (Compagno 1984; Olsen 1984). The second dorsal and anal fins are of roughly the same height and located opposite of each other, just anterior to the caudal peduncle (Ripley 1946; Olsen 1984). The caudal fin is fairly short and

notched, with a well-developed lower lobe that gives it somewhat of a double-tailed appearance (Olsen 1984).

Range, Distribution, and Habitat Use

Tope sharks occur in most of the world's oceans but have a discontinuous range that includes parts of the North and South Atlantic, North and South Pacific, Indian Ocean, and Mediterranean Sea (Compagno 1984; Walker
et al.
2020). More specifically, in the NE Atlantic Ocean, they range from Iceland, Faroe Islands, Norway, United Kingdom, Ireland, throughout the Mediterranean, southward to Cabo Verde (Cape Verde) and Senegal. In the SW Atlantic, they range from southern Brazil to Argentina. In the Eastern South Atlantic and Western Indian Oceans, they range from Angola to South Africa. In the Western South Pacific, they range from southern Australia to New Zealand. In the Eastern North and South Pacific, they range from British Columbia, Canada, south along the Baja California Peninsula and Gulf of California, Mexico, and from Ecuador south to Peru and Chile. Following the advent of improved species identification and reporting for sharks in the Gulf of Alaska in 1997, at least one tope shark has been documented in the Gulf of Alaska, but their occurrence in this region is considered quite rare (King
et al.
2017; Tribuzio
et al.
2022). Within the Mediterranean Sea, tope sharks are known to occur mainly in western parts of the sea, but do extend farther, including rare occurrences in the Adriatic Sea (Tsagarakis
et al.
2021). There are no records of tope sharks in the Sea of Marmara or the Black Sea (Colloca
et al.
2019). Occurrence of tope sharks is questionable along western Africa, from roughly Gambia and Guinea-Bissau to the Democratic Republic of the Congo, as well as off Mozambique in southeastern Africa and off Laysan Island in the Northwestern Hawaiian Islands (Cadenat and Blanche 1981; Compagno 1984; Compagno
et al.
2005; Walker
et al.
2020;
https://www.fishbase.org
). Although observations of tope shark within intertropical western Africa are recorded in FishBase (
https://www.fishbase.org,
last accessed on February 23, 2026), it is possible these are misidentifications, as other researchers specifically report having no observations of tope sharks in this region, and there are no reported catches of tope sharks in the Food and Agriculture Organization (FAO) of the United Nations (UN) fishery database for this region (
https://www.fao.org/fishery/en/collection/capture
).

Tope sharks are semi-pelagic and occur in shallow coastal areas, in continental shelf and slope waters, and in oceanic waters (Compagno 1984; Walker 1999; Thorburn
et al.
2019; Walker
et al.
2020; Schaber
et al.
2022). Distribution patterns and movements of tope sharks are complex and vary with multiple factors, including size, sex, habitat, and season. Immature tope sharks are typically found in coastal areas and in waters less than 200 meters (m) deep, with the smallest individuals (
e.g.,
<40 cm) remaining in shallower, coastal areas and larger juveniles having more expanded distributions (Olsen 1954; Olsen 1984; Stevens and West 1997; McAllister
et al.
2015; Thorburn
et al.
2019). Adult tope sharks occur in continental and insular shelf and slope waters, but also use pelagic, open-ocean areas and have been tracked at depths up to 826 m (Ripley 1946; Olsen 1984; Thorburn
et al.
2019; Schaber
et al.
2022).

Tagging studies indicate that while tope sharks can undertake long-distance migrations, they also exhibit general fidelity to a region. In several tagging studies, most sharks returned to or remained within 500 kilometers (km) of where they were initially released, while some sharks were recaptured thousands of kilometers away (Holden and Horrod 1979; Stevens 1990; Hurst
et al.
1999; Brown
et al.
2000; Fitzmaurice
et al.
2003; Thorburn
et al.
2019). The average distance that tope sharks range increases with size and age of the sharks (Stevens and West 1997; Brown
et al.
2000; Thorburn
et al.
2019). Medium and large-sized females are often recaptured at farther distances on average than males of the same size class (Brown
et al.
2000; Francis 2010; Thorburn
et al.
2019; Cameron
et al.
2025). However, several studies have found that some adult females travel similar distances as the adult males (Brown
et al.
2000; Walker
et al.
2000; Francis 2010; Thorburn
et al.
2019). Some researchers have hypothesized that this pattern of “partial female migration” reflects, at least in part, the use of local pupping areas by some females and use of more distant pupping areas by others (McMillan
et al.
2019; Thorburn
et al.
2019). Additional data are needed to understand the extent to which adult females display diversity in their use of pupping areas.

Spatial segregation of adult male and female tope sharks has been reported from many parts of its range including Australia (Olsen 1954; Olsen 1984; Walker 1999), California (Ripley 1946; Nosal
et al.
2021), Argentina (Lucifora
et al.
2004), South Africa (Freer 1992), Ireland (Fitzmaurice
et al.
2003, Cameron
et al.
2025), Scotland (Stevens 1990, Little 1995), England (Holdon and Harrod 1979), and the Alboran Sea (Muñoz-Chápuli 1984), indicating this is a common behavior within the species.

Tope sharks exhibit various migratory patterns that are often generally described as involving migration towards the poles during warmer months and migration towards the equator or into deeper, offshore waters during colder months (de Buen 1952; Olsen 1954, 1984; Lucifora
et al.
2004; Thorburn
et al.
2019). For example, in the SW Atlantic, tope sharks are present in greatest abundance off the coast of southern Brazil from June through September and move southward to Argentina by austral summer, peaking in abundance in Puerto Quequén (around 38°32′ S) from September to December, in Anegada Bay (around 40°30′ S) from October to December, and gulfs further south (around 43° S) between January and April (Peres and Vooren 1991; Ferreira and Vooren 1991; Elías
et al.
2005; Lucifora
et al.
2004; Chiaramonte 2015; Klippel
et al.
2016; Trobbiani
et al.
2021). These seasonal movement patterns are thought to be driven by oceanographic conditions, particularly by the seasonal shift in the front between the warm, subtropical, Brazil Current and the cold, subantarctic Malvinas (Falkland) Current and the associated changes in water temperature (Klippel
et al.
2016). A slightly different pattern occurs in the NE Atlantic, where tope sharks exhibit a cyclical seasonal movement pattern rather than north-south migration. Evidence from tagging and mark-recapture studies here show migration away from tagging sites and into deeper waters during winter and spring, and a return to coastal areas or areas close to (within about 50 km of) their original tagging site during summer and fall, consistent with the observed timing of mating in the region (Fitzmaurice
et al.
2003; Thorburn
et al.
2019).

Tope sharks also exhibit different patterns of vertical movement and use epipelagic (0-200 m depths) as well as mesopelagic habitats (200-1,000 m depths), depending on several factors including time of day and bathymetry (West and Stevens 2001; Thorburn
et al.
2019; Gonzalez-Garcia
et al.
2020; Schaber
et al.
2022). The vertical movements observed in tope sharks may be related to feeding behavior, including searching for prey (Cuevas
et al.
2014; Schaber
et al.
2022).

During spring and summer, pregnant females are often observed in shallow, coastal areas typically to give birth (Olsen 1984; Ripley 1946). Repeated observations of neonates, immediately

post-partum females and/or late-stage pregnant females have been used to confirm specific pupping and nursery areas in certain regions, although they have not been identified or fully resolved across the range. Within southeastern Australia, a number of bays and estuaries in Victoria and Tasmania have been identified as tope shark pupping and nursery areas, including the estuaries of Port Sorell, Pittwater, Georges Bay, and Great Oyster Bay in Tasmania, and Port Phillip Bay and Western Port Bay in Victoria (Olsen 1954, 1984; Steven and West 1997; Xiao
et al.
1999) and potentially inshore areas of the Great Australian Bight (Prince 1996; Braccini
et al.
2009; Rogers
et al.
2017; M.N. McMillan unpublished, cited in McMillan
et al.
2018). Stevens and West (1997) estimated that known pupping areas in southeastern Australia account for less than 10 percent of pup production needed to sustain the Australia tope shark stock, suggesting that other pupping areas exist. In New Zealand, pupping areas may be limited to coastal waters between the Hauraki Gulf and Kaipara Harbor along the North Island and between Oamaru and Jackson Bay along the South Island (Blackwell and Francis 2010; International Union for Conservation of Nature (IUCN) Species Survival Commission (SSC) Shark Specialist Group 2024a,b). However, Fisheries New Zealand (2024b) reports that the geographic location of the most important pupping and nursery grounds in New Zealand is not known. Available evidence indicates that pupping occurs throughout the Northeast Atlantic including near mainland Portugal, the Canary Islands, the Azores, inshore waters of England, Wales, and Ireland, and in the southern North Sea (Muñoz-Chápuli 1984; J.R. Ellis pers. comm., cited in Walker 1999; Thorburn
et al.
2019; Schaber
et al.
2022; Das
et al.
2025; Edwards
et al.
2025; IUCN SSC Shark Specialist Group 2025a,b,c; Loughs Agency
n.d.;
National Museums Northern Ireland
n.d.
). It is unclear if pupping occurs within the Mediterranean (Capapé
et al.
2005). In the SW Atlantic, pupping and nursery habitats are thought to be located in inshore waters of northern Argentina, and may include Bahía Blanca, Bahía de Samborombón, Bahía San Blas, Bahía Engaño and Golfo San Matías, as well as the Albardão region off Rio Grande do Sul, Brazil (G.E. Chiaramonte, pers. comm., cited in Walker 1999; Lucifora
et al.
2004; Bovcon
et al.
2018; IUCN SSC Shark Specialist Group 2025e). In South Africa, pupping has been reported to occur in the Gansbaai area and juvenile tope sharks have been caught in various embayments, including Struis, St. Helena, Walker, and False Bay, suggesting that these and/or nearby coastal areas may function as pupping or nursery grounds (Freer 1992; McCord 2005). Finally, in the NE Pacific, pupping areas include (or historically included) central California, the Santa Barbara coast, Tomales and San Francisco Bay, and potentially areas off Baja California Sur (Ripley 1946; Ramírez-Amaro
et al.
2013; Nosal
et al.
2021). No information is available on pupping or nursery areas in the SE Pacific.

Diet

Tope sharks prey on a wide range of demersal and pelagic fishes, as well as crustaceans, cephalopods, worms, and echinoderms (Compagno 1984). The diet of the species changes significantly with their development: juveniles consume more crustaceans and benthic invertebrates than adults, while adults consume a greater diversity of fishes and overall higher trophic level prey relative to juveniles (Lucifora
et al.
2006; Taborda 2018; Poiesz
et al.
2021; Priester
et al.
2024). Differences in the diet of males and females have been observed in some studies, although this could be explained by habitat use and seasonality rather than diet preferences (Ripley 1946). Although data are limited, tope sharks appear to be somewhat selective rather than strictly opportunistic foragers (Lucifora
et al.
2006; Biton-Porsmoguer 2022). Detailed information on prey species by region is available in section 2.5 of the Status Review Report.

Growth and Reproduction

Tope sharks are relatively long-lived, reaching a maximum age of at least 55 years (Coutin 1992; Walker
et al.
2020). Because sharks lack the calcified structures (
e.g.,
otoliths) typically used to age teleosts (bony fishes), age and growth estimates are often produced by counting vertebral growth bands or by using time at liberty and differences in length measurements collected during mark-recapture studies (Cailliet and Goldman 2004; Cailliet 2015; Harry 2018). For tope sharks, counting growth bands is considered reliable for small and medium-sized individuals but is likely to underestimate the age of older, larger individuals (
i.e.,
≥140 cm total length (TL) or ≥~11 years old) and therefore mark-recapture studies likely produce more accurate maximum age estimates (Moulton
et al.
1992; Walker
et al.
2001; Harry 2018). Studies relying on counts of vertebral bands have produced maximum age estimates on the order of 33 years for tope sharks off the coast of South Africa (Freer 1992; McCord 2005), 41 years for tope sharks off the coast of Brazil (Ferreira and Vooren 1991), and 50 years in Australia (Thomson
et al.
2020). Studies using tag-recapture growth data have produced maximum age estimates ranging from 46-59 years for females (n = 37) and 43-55 years for males (n = 16) in the NE Atlantic (Dureuil and Worm 2015), and 55 years to possibly 60 years for tope sharks tagged off southern Australia (Olsen 1953, 1954; Walker 1999).

Tope sharks exhibit fairly slow overall growth rates. Available estimates of von Bertalanffy's growth coefficient (K) for tope sharks are 0.164 year
−1
in Australia, 0.075 year
−1
for females and 0.092 year
−1
for males in Brazil, 0.124 year
−1
in Australia, 0.086 year
−1
for females and 0.154 year
−1
for males in New Zealand, 0.190 year
−1
in South Africa, and 0.076 year
−1
for females and 0.081 year
−1
for males in the NE Atlantic (Grant
et al.
1979; Ferreira and Vooren 1991; Moulton et al 1992; Francis and Mulligan 1998; McCord 2005; Dureuil and Worm 2015). Higher growth coefficients for males suggests that they reach their maximum lengths faster than females. Individuals grow most quickly during the first several years, followed by steady growth up to age 7-11 years, slowed growth as they approach or reach maturity, and then an eventual plateau (Grant
et al.
1979; Moulton
et al.
1992; Francis and Mulligan 1998; Fitzmaurice
et al.
2003; McCord 2005). Relative to females, male tope sharks reach maturity at smaller sizes and earlier ages, and attain slightly smaller maximum lengths and lower weights (Ripley 1946; Grant
et al.
1979; Freer 1992; Lucifora
et al.
2004; Capapé
et al.
2005; Walker 2005). Maximum theoretical length ranges from 163-201 cm for females and 142-177 cm for males (Ferreira and Vooren 1991; Francis and Mulligan 1998; Dureuil and Worm 2015). Tope sharks have an estimated age at maturity ranging from about 10 to 15 years in females, and 6 to 17 years in males. Length at first maturity ranges from 118-150 cm in females and 107-135 cm in males. Tope sharks are therefore considered a late-maturing species. Additional information on age and growth parameters for the species can be found in Table 2-1 of the Status Review Report.

Tope sharks exhibit yolk sac viviparity, meaning that eggs are fertilized and hatched internally, young are born alive, and nourishment of the embryo comes from the egg rather than from a placental connection to the

mother. Gestation is thought to last 12 months (Ripley 1946; Peres and Vooren 1991; Lucifora
et al.
2004; Capapé
et al.
2005); however, Theron (2001) and Walker (2005) suggest it may exceed 12 months. Data from multiple locations across the species' range, including Argentina, Brazil, southern Australia, South Africa, and California, provide evidence of a triennial (3-year) female reproductive cycle (Peres and Vooren 1991; Theron 2001; Lucifora
et al.
2004; Walker 2005; Nosal
et al.
2021). Males are thought to reproduce annually, and mating occurs seasonally within a local population (Peres and Vooren 1991; Freer 1992; Theron 2001). Females are capable of storing sperm for periods of weeks to months, and therefore mating may occur well in advance of fertilization (Peres and Vooren 1991; Theron 2001; Walker 2005). There is also evidence of multiple paternity (
i.e.,
multiple sires in the same litter) in tope sharks (Hernandez Muñoz 2013; Kelly
et al.
2025). Female fecundity increases with the size of the adult female as evidenced by increased number of oocytes per female, number of embryos per female, and number of pups per litter in larger females (Ripley 1946; Olsen 1984; Peres and Vooren 1991; Lucifora
et al.
2004; Capapé
et al.
2005; Walker 2005; Chiaramonte 2015). Litter size can range from 4-52 pups, with average litter size ranging from about 23-35 pups of equal sex ratio measuring approximately 240-370 millimeters (mm) total length (TL) (Ripley 1946; Peres and Vooren 1991; Freer 1992; Walker 2005).

Demography

The natural mortality rate (M) for tope sharks, which theoretically accounts for predation and all other natural sources of mortality, such as senescence, has been estimated to be low (M = 0.1006 year
−1
) for tope sharks of mixed age in Australia (95 percent confidence range: 0.08-0.12, n = 500; Grant
et al.
1979). This is equivalent to a survival rate (from natural death) of e
−0.1006
= 90.43 percent year
−1
. Estimates of natural mortality for tope sharks in other regions are also generally low: 0.123 year
−1
in Australia, 0.26 year
−1
in Australia, 0.126 year
−1
in South Africa, and 0.094 year
−1
in the NE Atlantic (Walker 1970 as cited in Walker 1999; Dow 1986 as cited in Walker 1999; McCord 2005; Dureuil 2013).

The intrinsic rate of population increase (r
max
), which is a function of fecundity, age of maturity, longevity, and natural mortality rate, is fairly low for tope shark populations. Using life history data available through FishBase (
https://www.fishbase.org
), life history parameter estimation software available through FishLife 2.0 (Thorson
et al.
2017; Thorson
et al.
2023), and a Leslie-matrix approach, Winker
et al.
(2019) calculated an r
max
value of 0.041 (CV = 0.154) for tope sharks. Using five different methodologies, Cortés (2016) calculated r
max
values of 0.042-0.086 for tope sharks in the SW Atlantic and 0.047-0.169 for tope sharks in the SW Pacific. Smith
et al.
(1998) developed a model that uses female age at maturity, maximum reproductive age, and average fecundity to calculate a productivity metric referred to as the intrinsic rebound potential (IRP), which essentially estimates potential population growth rate after harvest mortality is removed. Using biological data collected for tope sharks in southern Australia and under an assumption of no increase in fecundity, Smith
et al.
(1998) calculated an IRP of 0.033 and a corresponding population doubling time of 21.3 years. Under an assumed 25 percent increase in fecundity (to account for increased survival of older, larger females), the IRP increased to 0.045 with an associated doubling time of 15.4 years (Smith
et al.
1998). Across the 26 shark species considered in their comparative analysis, these authors found a wide range of rebound rates (
i.e.,
0.017-0.202), with the tope shark among the species estimated to have a relatively low to moderate IRP (Smith
et al.
1998).

Winker
et al.
(2019) estimated a median generation length of 23.1 years (CV = 0.066). Similarly, the most recent IUCN Red List assessment of tope shark applied a similar estimated generation length of 26.3 years (Walker
et al.
2020), while the Australian Fisheries Management Agency (AFMA), in their rebuilding strategy for the species, uses an estimated generation length of 22 years (AFMA 2015).

Population Structure

Tagging and genetic data indicate that
G. galeus
is structured as at least six regional populations: (1) a NE Atlantic population that extends from the North Sea and UK waters into the Mediterranean Sea and southward to northwest Africa; (2) a So. Africa population that extends from Namibia to East London, South Africa; (3) a SW Atlantic population that ranges from southern Brazil to Patagonia; (4) a NE Pacific population that ranges from British Columbia, Canada to southern Baja California, Mexico, and including the Gulf of California; (5) a SE Pacific population that ranges from Ecuador to Chile; and (6) a SW Pacific population that includes Australia and New Zealand. No movement of tope sharks among these regions has been reported, and available genetic data indicate that gene flow among these six regional populations is limited (Ward and Gardiner 1997, Chabot and Allen 2009, Chabot 2015, Hernández
et al.
2015, Bester-van der Merwe
et al.
2017).

Current understanding of tope shark population structure is based largely on several studies that examined population genetics of tope sharks on broad geographic scales. Most recently, Bester-van der Merwe
et al.
(2017) investigated population structure of tope sharks by collecting and analyzing genetic samples from five countries: Argentina, Chile, South Africa, Australia (Tasmania), and New Zealand. Genetic variation was assessed based on both nuclear DNA (nDNA) (19 microsatellite markers, n = 185 samples) and mitochondrial DNA (mtDNA) (n = 96 samples). Similarly, a pair of studies by Chabot and Allen (2009) and Chabot (2015) used both microsatellites (n = 11 markers) and an mtDNA marker (1,068-base pair fragment in the control region) to investigate the population structure of tope sharks from multiple locations across the species range: South America (Peru, n = 11; Argentina, n = 1), South Africa (Cape Town, n = 16), Australia (GAB, New South Wales, and Tasmania, n = 50), North America (Southern California, n = 26), and the United Kingdom (Irish and Celtic Seas, n = 12). (Note: Chabot (2015) pooled their single sample from Argentina with the Peru samples into a collective South America population based on the observation of Chabot and Allen (2009) that it shared an identical mtDNA haplotype with two samples from Peru.) All three studies detected a high degree of genetic differentiation among the sampled regions (Bester-van der Merwe
et al.
2017: F
CT
= 0.137, Ф
ST
= 0.895, p < 0.05; Chabot and Allen 2009: Ф
ST
= 0.84, p < 1 × 10
−6
; Chabot 2015: F
CT
= 0.15, p < 0.001). The results of pairwise comparisons between regions provide additional support for population structuring at a regional scale. For instance, pairwise comparisons by Bester-van der Merwe
et al.
(2017) using microsatellite data indicated significant but varying magnitudes of genetic differentiation between all sampled regions (F
ST
= 0.050 to 0.330, p < 0.05), with the lowest observed differentiation occurring between Chile and New Zealand (F
ST
= 0.050) and highest between Argentina and Australia (F
ST
= 0.330). Similarly, pairwise comparisons by Chabot (2015) using microsatellite data and three different statistics (F
ST
, G”
ST
, and Jost's D) consistently indicated significant genetic

differentiation between all sample regions. Pairwise comparisons by Chabot and Allen (2009) using mtDNA also revealed significant differences (Ф
ST =
0.34-0.90, p < 1 × 10
−6
) for all pairs, and, based on Ф
ST
values, among-population differences accounted for 83.96 percent of the observed genetic variation. These researchers identified 38 unique haplotypes, 2 of which were shared between sampling regions. One, as noted earlier, was shared between Argentina and Peru, and the other was shared between South Africa and Australia. With the exception of Australia and New Zealand, all pairwise comparisons of mtDNA in Bester-van der Merwe
et al.'
s (2017) study also indicated significant and strong population structuring (Ф
ST
= 0.151-0.934, p < 0.05), with the lowest difference between Chile and Argentina (Ф
ST
= 0.151). Bester-van der Merwe
et al.
(2017) identified 15 unique haplotypes, one of which was shared between Chile and Argentina and one between Australia and New Zealand. The very low and non-significant measure of pairwise variation for the mtDNA marker between Australia and New Zealand (Ф
ST
= −0.180) reported by Bester-van der Merwe
et al.
(2017) is an exception to the otherwise consistent pattern of significant genetic differentiation among sampled regions. An earlier study by Hernández
et al.
(2015) also examined genetic samples from Australia and New Zealand using a different mtDNA marker, 8 microsatellite markers (versus 19), more sample locations within each country, and substantially more mtDNA samples and microsatellite samples than Bester-van der Merwe
et al.
(2017). Results of Hernández
et al.'
s (2015) study indicated that genetic differentiation between the Australia and New Zealand samples based on mtDNA was low and non-significant (after sequential Bonferroni correction, α = 0.0014), and that the microsatellite variation was also low and non-significant (p > 0.05; Hernández
et al.
2015).

Estimates of gene flow (in terms of migrants per generation) by Chabot and Allen (2009) among sampled locations were very low and ranged from 0.05 to 0.97. Estimates of gene flow by Chabot (2015) between sampled locations were also very low (0.002-0.013), with the exception of the migration rate from South into North America, which was higher than all others (0.257). However, the estimated migration between North and South America in this study was well below the estimated self-recruitment rates (0.692 and 0.988); and, as discussed earlier, the pairwise comparisons between North and South America based on mtDNA and microsatellites showed significant genetic differentiation (Chabot and Allen 2009; Chabot 2015).

Overall, and notwithstanding data gaps due to under- and non-sampled parts of the range, these studies indicate a regionally isolated population structure, with little to no contemporary connectivity between tope shark populations across ocean basins or the equator. Additional information about finer-scale population structure is available in section 2.8 in the Status Review Report (see also Distinct Population Segment Analysis section of this document).

Population Abundance and Trends

A global abundance estimate for tope sharks is not available; however, the most recent IUCN Red List assessment (Walker
et al.
2020) provides a trend analysis for the species on a range-wide level as well as several regions. This analysis was based on the following data from five geographic locations and four of the six regional tope shark populations (the NE and SE Pacific populations were omitted): (1) standardized catch per unit effort (CPUE) data for the NE Atlantic from fisheries-independent trawl surveys and the Azorean bottom long-line fishery (International Council for the Exploration of the Sea (ICES) 2019); (2) nominal CPUE data from the demersal trawl fisheries in Argentina (G. Chiaramonte unpublished data 2019); (3) estimated biomass trends from a stock assessment for South Africa (Winker
et al.
2019); (4) estimated biomass trends from a stock assessment for Australia (Thomson and Punt 2009); and (5) standardized CPUE from longline and gillnet surveys in New Zealand (Dunn and Bian 2018). The trend data from each source were analyzed over three generation lengths using a Bayesian state-space modeling tool specifically designed for use in IUCN Red List assessments for pelagic sharks, referred to as the `Just Another Red List Assessment' (JARA) tool (see Sherley
et al.
2020). This modeling tool was built off of the existing and open-source software referred to as `Just Another Bayesian Biomass Assessment' (JABBA), which is an extension of a standard Surplus Production Model framework that incorporates a Bayesian approach to account for potential process (
i.e.,
model-based) and observation (
i.e.,
sampling-based) error (Winker
et al.
2018). The JARA analysis yields an annual rate of change, a median percentage change over three generation lengths, and the probability of the most likely IUCN Red List Category.

Population trends were estimated using the JARA framework for each of the five datasets mentioned above, and those regional trend estimates were then used to estimate a global population trend, with regional trend data weighted by the size of the particular region in proportion to the species' total distribution. This analysis estimated a median percentage decline of −76.6 percent, −99.3 percent,−91.4 percent, −90.1 percent, and −29.8 percent over three generations (79 years) for the NE Atlantic, SW Atlantic, So. Africa, Australia, and New Zealand populations, respectively, and a global decline of −88 percent (95 percent CI: −99.6 to −65.7 percent) (Walker
et al.
2020, see Supplemental Information). However, the authors do note several important caveats. For example, to incorporate regions where the species is known to occur but where trend data were not available (
e.g.,
NE Pacific, SE Pacific), Walker
et al.
(2020) assumed that each missing regional population had declined by between 0 and 100 percent by randomly sampling from a uniform distribution, U(−100,0), and then combined this value (weighted by proportional area) with other regional estimates to calculate the global trend. Additionally, when datasets do not span three generation lengths, as was the case for all the regions in this analysis, JARA requires that trends be projected forward in time, effectively extrapolating beyond the available data and compounding the uncertainty in the estimated trends. For several regions (
i.e.,
NE Atlantic, SW Atlantic, and New Zealand), these extrapolations represented approximately two-thirds of the time series used in the analysis. Overall, given the lack of long-term monitoring for this species, each regional trend estimate was necessarily derived from very limited information—sometimes just a single fishery-dependent CPUE series or assessment—which may not capture important underlying factors, such as stock structure, age and size composition, or regional differences in fishing practices (see also Kai 2021). Available information on abundance and trends by region is discussed below.

In some cases, stock assessments have been conducted on the regional tope shark population to evaluate the status of the stock for fisheries management purposes. Stock assessments often indicate the status of a stock using the terms “overfished” and “overfishing.” Specific to the context of the Magnuson-Stevens Fishery Conservation and Management Act (MSA), a stock or stock

complex is considered “overfished” when its biomass has declined below minimum stock size threshold (MSST), defined as the level of biomass below which the capacity of the stock or stock complex to produce maximum sustainable yield (MSY) on a continuing basis has been jeopardized (50 CFR 600.310(e)(2)(i)(E)-(F)). Overfishing occurs whenever a stock or stock complex is subjected to a level of fishing mortality or total catch that jeopardizes the capacity of a stock or stock complex to produce MSY on a continuing basis (50 CFR 600.310(e)(2)(i)(B)). While the stock assessments referenced in this finding do not define “overfished” and “overfishing” using the exact language above, they use the two terms with equivalent meanings. It is important to note that the terms “overfished” and “overfishing” do not have any specific relationship to the terms “threatened” or “endangered” as defined in the ESA. While a stock that is overfished is not able to sustain an exploitive fishery at MSY (
i.e.,
the highest possible annual catch that can be sustained over time), it can still be at a stable biomass level and thus not in danger of extinction due to overutilization. Similarly, one goal of the MSA (and fisheries management organizations) is to “rebuild” overfished stocks to biomass levels that will support MSY. This level can be significantly above the biomass levels necessary to ensure that a species is not in danger of extinction. Thus, evidence of declining abundance that threatens the ability of the fishery to provide MSY is relevant, but not dispositive of a threatened or endangered species determination. Therefore, while available information about whether specific stocks are overfished or experiencing overfishing is relevant to and considered in the ESA extinction risk analysis, the fact that a stock may be considered “overfished” or experiencing “overfishing” does not automatically indicate that any particular status is appropriate under the ESA. Stock assessments, which provide information for determining the sustainability of a fishery, are based on different criteria than status reviews conducted under the ESA, which provide information to assess the likelihood of extinction of the species. When conducting a status review under the ESA, we use relevant information from available stock assessments, such as levels of biomass and fishing mortality, and apply the ESA's definitions of threatened and endangered species to the information in the record using NMFS' standard tools of ESA extinction risk analysis. As part of the ESA extinction risk analysis, when examining whether overutilization for commercial purposes is a threat to the species, the status review considered whether the species has been or is being harvested at levels that contribute to or pose a risk of extinction to the species.

NE Atlantic

Quantitative data on abundance trends of
G. galeus
in the NE Atlantic region are limited. While several fishery-independent surveys are available from across the region, there are various design and sampling flaws or errors preventing us from drawing strong conclusions about population trends. Five research surveys coordinated by ICES and spanning 1992 to 2022 were considered by the ICES Working Group on Elasmobranch Fisheries (WGEF) in their 2023 review of the tope shark. Tope sharks are not sampled effectively in these surveys due to low gear selectivity, and therefore, trend analyses using these data should be “viewed with care” (ICES 2022). However, one of the five surveys, International Bottom Trawl Survey (IBTS)-Q1, had a low catch rate of tope sharks over the time period and was not subject to further analysis by WGEF (ICES 2023a), and a second of these surveys, IBTS-Q3, included some questionable data and species identification issues such that the WGEF concluded the dataset could not be relied upon until the data could be verified (ICES 2022). Two other trawl surveys considered by the WGEF are France's “Evaluation Halieutiques Ouest de l'Europe” Groundfish Survey (EVHOE-WIBTS-Q4), which is conducted in the Bay of Biscay and Celtic Sea, and the Irish Groundfish Survey (IGFS-WIBTS-Q4), which is conducted in the shelf waters around Ireland (ICES 2023a). Neither dataset indicates a clear abundance trend: the data show sporadic peaks in annual catch generally related to a large number of specimens captured in single hauls (ICES 2023a). The fifth survey considered by the WGEF is the spring bottom longline survey of waters around the Azores archipelago (ARQDAÇO) that has been conducted almost annually since 1995. The survey is not particularly well-suited to capturing tope sharks, and both the biomass estimates and standardized abundance index derived from these survey data are highly variable over time and do not indicate a clear trend (ICES 2023a). Santos
et al.
(2020) analyzed ARQDAÇO survey data and compared them to commercial landings data, and reported that annual landings for tope sharks showed a decreasing trend from 1998/2000 to 2009, and then some rebound after this period. Santos
et al.
(2020) hypothesized that the relatively lower landings in the more recent years reflect an increased discard rate, which may have been driven in part by low market demand. This hypothesis receives some support from their finding that the standardized CPUE for tope sharks in the fisheries data is fairly stable over time. The authors cautioned that neither the abundance index nor the CPUE data should be interpreted as an accurate proxy for tope shark abundance in the region due to the low and variable catch rates of tope sharks and likely changes in discard rates in the longline fisheries.

As part of the most recent IUCN Red List assessment of tope sharks, Walker
et al.
(2020) assessed trends for the entire NE Atlantic regional population of tope sharks using three datasets: the Bay of Biscay and Celtic Sea trawl surveys (
i.e.,
EHVOE-WIBTS-Q4) from 1997-2016; the Irish Ground Fish Survey (
i.e.,
IGFS-WIBTS-Q4) from 2005-2018, and the Azorean bottom long-line fishery landings during 1990-2015 (see Walker
et al.
2020, Supplementary Information). Results of the JARA analysis using these three datasets indicate an annual rate of reduction of 1.7 percent for the combined 29 years of survey data (1990-2018) and projected an estimated median reduction of 76.6 percent over the next three generations (79 years). Walker
et al.
(2020) noted that this trend was largely driven by the higher catch rates occurring at the start of the time-series, with data from the latter part of the time-series indicating more stable trends. The authors also reiterated the concerns raised by the WGEF that the various datasets for the NE Atlantic may not be representative of the population due to low catchability of tope sharks in the surveys and gears used and therefore cautioned how the data were interpreted. In addition, the 95 percent credible intervals on the model-predicted population trend are wide and skewed upwards over the forecasted three generations. Lastly, it is also worth noting that the more recent years (
i.e.,
since 2018) of trawl survey data from EHVOE-WIBTS-Q4 (Bay of Biscay and Celtic Sea) in which CPUE and biomass estimates show some increases are not captured in this analysis as these data were likely not available at the time.

Beyond these available survey data, additional, reliable quantitative data regarding tope shark abundance trends in the North Atlantic Ocean are very limited. Some data, however, are available from the Irish Marine Sportfish Tagging Program, which

between 1970 and 2015, recorded 448 recaptures of 7,641 tagged tope sharks (ICES 2020). Using Jolly-Seber mark-recapture modeling, the WGEF reported that these data indicate a stable population trend around Ireland between 1970 and 2015 (ICES 2020).

Within the Mediterranean and Black Seas, fishery-independent survey data are available from the Mediterranean International Trawl Survey (MEDITS), an international survey effort formalized in 1993 by Spain, France, Italy and Greece, and expanded in 1996 to include Albania, Croatia and Slovenia. These standardized bottom-trawl surveys have been conducted since 1994 throughout 19 subregions along the northern margin of the Mediterranean basin. Encounters with tope sharks are generally infrequent, varying by geographical subarea (GSA) (Relini
et al.
2010; Marongiu
et al.
2017, Ramírez-Amaro 2017; Geraci
et al.
2017; Follesa
et al.
2019). Ramírez-Amaro (2020) provided MEDITS summary data for 199 hauls completed during 1994-2015 in the western Mediterranean, specifically the northern Alboran Sea (GSA 1), northeastern coast of Spain (GSA 5), and Balearic Islands (GSA 6). A total of 38 tope sharks were captured across 13 of the 22 survey years in the Alboran Sea (GSA 1); no tope sharks were captured in GSA 5 or GSA 6. Previously, Muñoz-Chápuli (1984) had reported that, in 1981, in 95 commercial longline sets and 81 commercial trawls in the western Alboran Sea, a total of 34 male and 3 female tope sharks were recorded as captured off the southern coast of Spain, and 9 males and 2 females were recorded as being captured off the coast of northern Morocco. At the time of their study, Muñoz-Chápuli (1984) also described
G. galeus
as a species that was very often caught by hook-and-line gear. Although the differences in gear types and fishing effort prevent a direct comparison of the MEDITS data to the data provided by Muñoz-Chápuli (1984), the apparent decline in captures of tope shark between these two datasets may indicate an abundance decline in the Alboran Sea area.

No tope sharks were observed in the MEDITS trawl surveys conducted around Sardinia (GSA 11) from 1994 to 2015 (Marongiu
et al.
2017, Ramírez-Amaro 2017). Tope sharks were also not observed in MEDITS surveys conducted from 1994 to 2009 in the northern Tyrrhenian Sea (GSA 9), south of Sicily (GSA 16), in the Adriatic Sea (GSA 17, 18), or in the western Ionian Sea (GSA 19) (Relini
et al.
2010). Two individuals were captured in the southern Tyrrhenian Sea (GSA 10) during this period—one in 1995 and one in 2001 (Relini
et al.
2010). Follesa
et al.
(2019) provided MEDITS data for the period 2012-2015 for GSA 1, 5-11, 16-20, 22, 23, and 25. Tope sharks were captured only in GSA 16 (south of Sicily) during this period, but at very low frequency (0.5 percent of hauls in 200-800 m depth strata). No tope sharks were observed in MEDITS surveys in GSA 16 from 1994 to 2012 (Geraci
et al.
2017).

Additional information on the general distribution and abundance of tope sharks comes from an international, standardized assessment of shark bycatch rates in commercial swordfish and tuna longline fisheries across nine regions of the Mediterranean Sea conducted during 1998-1999. Tope sharks were captured in 6 of the 9 regions, with highest catches occurring in the 3 westernmost regions: the Alboran Sea (n = 10 sharks/1,391 longline sets), the Balearic Islands (n = 4 sharks/1,379 longline sets), and the Catalan region (n = 2 sharks/331 longline sets) (Megalofonou
et al.
2005). A single tope shark was also reported in each of 3 other regions where reported fishing effort was much lower: the Straits of Sicily, the Aegean Sea, and the Levantine basin (32, 141, and 218 longline sets, respectively). Catch rates (expressed as number of fish/1,000 hooks) were low across all areas, with the highest catch rates occurring in the Levantine basin (0.143) and Aegean Sea (0.057). The species was not observed in the Adriatic Sea (777 longline sets), the Ionian Sea (833 longline sets), or the Tyrrhenian Sea (9 longline sets) (Megalofonou
et al.
2005). Authors note that this may indicate low or depressed abundances and/or low capture efficiency of the gear used (Megalofonou
et al.
2005).

The above data contrasts with landings of tope sharks reported to International Commission on the Conservation of Atlantic Tunas (ICCAT) by Türkiye averaging 565 metric tons (mt) per year (ranging from 413 mt to 668 mt) from 2004 to 2009 in their shark longline fishery (
https://www.iccat.int/en/accesingdb.html,
accessed on June 27, 2024). The large difference between the ICCAT data and the tope shark landings reported by Megalofonou
et al.
(2005) may be explained by the fact that the catches reported to ICCAT by Türkiye came from the longline fishery specifically targeting sharks. No tope shark landings, which are reported voluntarily, were reported by Türkiye after 2009. We also note that no tope shark landings data for Türkiye are included in available FAO data (
https://www.fao.org/fishery/statistics-query/en/capture
), which creates significant uncertainty regarding the reliability of the available data. The only other Mediterranean landings data in the ICCAT database are for France, which reported landing 5 mt by trawl in 2010, and Morocco, which reported landing 6 mt in 2011, 2 mt in 2012, and 4 mt in 2013 by handline, longline, and purse seine.

Some available evidence suggests a decline in tope shark abundance within the western Mediterranean. In 2016-2017, a group of 42 bottom trawl, bottom longline, and drifting longline fishermen who were interviewed in Costa Brava, Spain (coastal Catalan region) generally considered tope shark populations to be declining locally, although the statistical distribution of answers was not significantly different than that expected by chance (Nuez
et al.
2021). Around this same time period, in 2015, the government of the Balearic Islands classified the species as “critically endangered” in local waters using the IUCN Red List criteria, stating that it had “gone from being frequent in shops and markets to being rare, with a sharp decrease in catches” (Grau
et al.
2015). The critically endangered classification is described as being based on direct observations and actual or potential exploitation levels indicating a reduction in biomass of at least 80 percent in the last ten years or in three generations of the species, and that the reduction and its causes had not ceased, or are not understood, or are not reversible (Grau
et al.
2015). It is not clear, however, what data were used in support of the observed decline. Additionally, a historical abundance decline in the northern Tyrrhenian Sea over the years 1898-1922 is indicated by Ferretti
et al.
(2005)'s analysis of commercial landings data for fish “traps” targeting Atlantic bluefin tuna: large declines (>90 percent) were observed for all sharks species over this 25-year period, with tope sharks estimated to have declined by 99.97 percent (95 percent CI: over 99.99 percent to 99.38 percent). While Ferretti
et al.
(2005) do not discuss taxonomic or reporting issues for tope sharks in the data, given the documented issues with species-specific landings records in this region, confidence in the historical landings records used in the study is somewhat limited.

G. galeus
is also known to occur along the coast of Algeria and Tunisia, in some cases arriving after long-distance migrations from the North Atlantic (Holden and Horrod 1979, Fitzmaurice
et al.
2003). Capapé
et al.
(2005) noted that, at the time of their study, tope sharks were the most “abundantly and regularly” landed shark species off the coast of Algeria, and that tope sharks

were also being captured off the coast of Tunisia, where it was later referred to as “quite common” by Ragonese
et al.
(2013). Likewise, Bradaï
et al.
(2006) described the Gulf of Gabès as an area where tope sharks are “regularly observed.” As part of a population genetics study, Thorburn (2015) was able to acquire 28 samples of
G. galeus
from sport fishers and fish markets along the Algerian coast in 2009-2013, indicating that the species was still encountered in local waters at that time. We are not aware of any additional data or surveys that have been conducted along the southern margin of the Mediterranean Sea that would aid in characterizing the species' relative abundance or abundance trends.

In a relatively recent review of published literature and existing databases, tope sharks were categorized as rare in the western, central, and eastern Mediterranean and Adriatic Sea, and as having a declining probability of occurrence (Serena
et al.
2020). This study involved a comprehensive review of available data and reports for both European Union (EU) and non-EU countries bordering the Mediterranean, and examined both fisheries-independent data (
e.g.,
MEDITS) and landings data from industrial and small-scale fisheries. When considered collectively, this recent review, and other evidence (
e.g.,
Ferretti
et al.
2005) suggest that tope sharks may have undergone a substantial decline in abundance within the Mediterranean.

No assessments of abundance trends are available for the eastern central Atlantic.

In sum, population trends and abundance of tope sharks within the NE Atlantic region remain poorly understood. Quantitative assessments of tope shark abundance in the NE Atlantic region suffer from various design and sampling flaws or errors, preventing us from drawing strong conclusions about population trends. Overall, however, data from the individual systematic surveys of the North Sea, Celtic Seas, English Channel, and Biscay Bay do not indicate that the NE Atlantic tope shark population has changed significantly over the respective data collection periods. Systematic surveys around the Azores also provide no evidence of a decline in abundance of tope sharks. Tope sharks are relatively rare in the Mediterranean, and available evidence suggests a large historical decline in abundance in this subregion. While the most recent IUCN assessment (
i.e.,
Walker
et al.
2020) projects a declining trend overall for tope sharks in the NE Atlantic, the high level of uncertainty associated with this projection weakens confidence in this result.

So. Africa

There are two main studies that characterize
G. galeus
population abundance and trends in the So. Africa region. Both studies are focused on the waters around South Africa, which is the core of the species' distribution here. First, Best
et al.
(2013) compiled landings and observation data from a wide array of sources to assess the status and long-term population trends of the major chondrichthyan species in False Bay, as well as their vulnerability to extinction. The data sources included historical trawl and beach-seine scientific surveys, commercial trawl, demersal shark longline, linefish, and beach-seine catch returns, recreational shore-angling records, underwater observations, spearfishing competition records, and rotenone surveys. These datasets cover various time periods that collectively span 1897 to 2011, and the authors note that the quality and quantity of the data varied considerably, preventing them from using a consistent protocol to analyze the datasets together. Of the 37 chondrichthyan species documented in the combined dataset,
G. galeus
was the most commonly encountered species, with over twice as many records as the second-most commonly recorded species,
M. mustelus
(Best
et al.
2013). It was also the only species for which multiple data sources consistently indicated a statistically significant decline in abundance based on rank correlation analysis. This analysis used CPUE estimates based on catch and effort data from the commercial beach seine, recreational shore-angling, and demersal longline datasets, which collectively spanned the years 1969 to 2011. However, it is important to note that the recreational shore-angling fishery began on the eastern and western shores of the bay, which are adjacent to the deeper-water habitats where tope sharks may be found, but has since moved to shallower, more accessible sandy beach areas, where tope sharks do not typically reside. Thus, the declining trend in
G. galeus
CPUE based on the recreational shore-angling dataset may in part be attributable to this evolution of the fishery.

More recently, Winker
et al.
(2019) also used a combination of datasets, including fisheries catch data and fishery-independent survey data, to estimate the population trend and stock status for tope sharks throughout South African waters more broadly. Using JARA, an abundance trend for tope sharks was estimated based on a fishery-independent demersal trawl survey conducted along the south coast of South Africa roughly every autumn and spring from 1991 to 2016. Tope shark abundance was found to have steadily declined at an average rate of approximately −2.7 percent per year from 1991 to 2016, yielding an estimated population decline of −50.9 percent over the full survey period (Winker
et al.
2019). Winker
et al.
(2019) then used this procedure to project the population trend over three generation lengths (~69 years, based on an estimated generation length of 23.1 years) beginning in 1991. This analysis predicted a total population decline of −85.1 percent by the year 2060, compared to 1991, though the 95 percent confidence interval around this estimate is very wide, spanning a range of possibility that includes a stable population trend and even slight population growth (Winker
et al.
2019).

In addition to estimating the abundance trend from the demersal trawl survey, Winker
et al.
(2019) also evaluated the status of the
G. galeus
fishery stock in South Africa relative to estimated harvest levels using the JABBA modeling procedure. Inputs to this analysis included the abundance index derived for the JARA analysis described above and an aggregated time series using data from the aforementioned demersal trawl survey (1992-2016), commercial linefish catch reported in South Africa's National Marine Linefish System (NMLS) database (1990-2016), catch data from the Department of Agriculture, Forestry, and Fisheries demersal shark longline database (1992-2016), and historical catch reconstructed from shark dealer sales in Gansbaai (described as the center of the South African shark fishery in the 1950s) (1952-1989). It is worth noting that the authors relied on several assumptions to address various uncertainties in these datasets, and these may have influenced the results of the analysis to some degree. For the demersal trawl and linefish datasets, for example, a portion of the shark catch was not reported to the species level. In order to include this portion of the catch in their analysis, the authors used two slightly different approaches to estimate the proportion of
G. galeus
in the unidentified portion of the two datasets. Each applied a conversion function that was based on the proportion of
G. galeus
observed in the species-specific portion of the shark catch. Additionally, for the linefish dataset, to estimate the historical catch before the beginning of official reporting to South Africa's

NMLS database (
i.e.,
before 1990), the authors relied on shark dealer sales from the Gansbaai fishing port, which they scaled up by a factor of 1.54 to account for catches from other regions. This value was based on the ratio of total catch reported in Gansbaai compared to total catch in the NMLS database in the year 1987. It is not clear how potential inaccuracies in these assumptions may have affected the downstream modeling results, so the conclusions of this analysis should be interpreted with caution. Commercial catch of
G. galeus
was found to have declined substantially from 1952 to 2016, corresponding to a predicted decline in population biomass that largely matched the results of the JARA analysis. Model estimates from four modeling scenarios indicated that biomass of the
G. galeus
population in South Africa has declined from approximately 93-94 percent of carrying capacity in 1952 to 10-14 percent of carrying capacity in 2016, and that there is a greater than 97.5 percent likelihood that if catch of
G. galeus
continues at its catch rate at the time (~329 mt per year), commercial extinction of the species in South Africa (
i.e.,
when biomass reaches a point where fishing the species is not commercially viable) would occur by 2055 (Winker
et al.
2019). According to Winker
et al.
(2019), the harvest rate must be reduced to less than 100 mt per year in order to reverse the declining trend and allow for positive population growth.

We did not find any information on population abundance or trends from other parts of the region outside of South Africa, such as along the southwestern African coast where the species is also thought to occur.

In sum, the best available information indicates that abundance of
G. galeus
has declined significantly in South Africa, which is the core of its distribution in this region, since the mid-20th century. An analysis of multiple fisheries datasets (
e.g.,
recreational angling, demersal longline, and beach seine fisheries) indicates that
G. galeus
was the most commonly encountered chondrichthyan species in the region from 1969 to 2011, but underwent a “dramatic and consistent” population decline (Best
et al.
2013). This decline was attributed to the species' long history of commercial exploitation in the region, exacerbated by its low biological resilience to such exploitation (Best
et al.
2013). A broader analysis using several, novel modeling approaches, indicates that
G. galeus
has likely experienced unsustainable fishing pressure since at least the 1950s and that current population biomass is estimated to be less than 15 percent of the population's carrying capacity (Winker
et al.
2019). Model projections suggest that fishing pressure must be significantly reduced (by over 60 percent) for the species to begin to rebound. Together, these studies indicate a major long-term reduction in
G. galeus
abundance in So. Africa caused by past and ongoing fishing pressure.

SW Atlantic

There have not been any formal assessments of tope shark abundance in the SW Atlantic region. However, several fisheries-derived CPUE datasets, anecdotal accounts from regional experts, and reported changes in local fishing strategies indicate, in aggregate, that the tope shark population in the SW Atlantic has declined significantly since the peak of fishing effort in the 1980s and 1990s.

A 24-year CPUE dataset from the demersal trawling fleet in Argentina provides some indication of the
G. galeus
population trend from 1992 to 2015 (Chiaramonte unpublished 2019, cited in Walker
et al.
2020). Based on this relative abundance index, tope shark abundance declined significantly from 1992 to 2000 and remained at this reduced level until the end of the dataset (Walker
et al.
2020). Using JARA, Walker
et al.
(2020) estimated an annual rate of population reduction of −5.9 percent, consistent with an estimated median reduction of −99.3 percent over three generation lengths (79 years). It is worth highlighting that CPUE in this study was calculated in terms of kilogram (kg) per trip, so the dataset does not account for variations in fishing effort between trips.

Lucifora (2003) designed a matrix-based population model to describe the baseline demographics of tope sharks in the Bahía Anegada region in Buenos Aires Province, Argentina. The model was also used to simulate population trends under several hypothetical scenarios based on existing fishing conditions at the time and potential alternative scenarios. Lucifora (2003) found that the predicted population trend was negative for all scenarios that simulated the possible fishing conditions at the time. The scenario that best represented the existing conditions in Bahía Anegada based on the author's knowledge of the fishery (
i.e.,
fishing for both adults and large juveniles) yielded a projected rate of population decline between −6.7 and −12.8 percent annually. Notably, this model-based estimate roughly reflects the average rate of population decline derived from the 24-year CPUE dataset discussed above (−5.9 percent; Walker
et al.
2020).

Chiaramonte (1998) provided an estimate of CPUE from the tope shark gillnet fishery in Necochea from 1990 to 1996, which the author described as “the most important directed shark fishery in the South-West Atlantic.” CPUE fluctuated significantly during this period without any discernible trend. Moreover, the author noted that changes to certain features of the fishery during the study period, such as to the gear and fishing effort, limit the reliability of this CPUE estimate as an indicator of tope shark abundance (Chiaramonte 1998).

A study by Villwock de Miranda and Vooren (2003) estimated CPUE in Brazil's Rio Grande do Sul fishery in the period 1975-1997, basing their estimates on the associated number of fishing trips for each of the main gear types in which
G. galeus
is captured. While the study differentiated landings by broad categories of sharks rather than by species, varying seasonality of landings from each of the five gear types was used as a reasonable indication of the species that are likely represented by the CPUE estimates for each fishery. For example, the authors note that until 1988, the majority of “cação” landings came from the simple trawl fishery, of which approximately 81 percent was caught during the winter months from May to October. Given the winter residency of
G. galeus
and
M. schmitti
in this region, the authors assumed that simple trawl CPUE estimates generally reflected the combined abundance of these two species. Overall, CPUE estimates of both the simple and pair trawl fisheries show a similar pattern of severe decline following a peak in landings in the mid-1980s. Simple trawl CPUE increased from 1975 to 1987, which the authors interpreted as reflecting a shift in the fishery from targeting primarily
G. galeus
in earlier years to increasingly retaining
M. schmitti
as well. In the ensuing years, simple trawl CPUE declined dramatically and from 1992 to 1997 averaged approximately 20 percent of its peak level in 1985-1987. As oceanic bottom gillnets gradually replaced trawls as the principal gear type for capturing “cação” in the early 1990s, oceanic gillnet CPUE estimates were nearly ten times greater than those of the simple trawl fishery. However, Villwock de Miranda and Vooren (2003) cautioned that the two datasets were not directly comparable, because the oceanic gillnet fishery specifically targeted “cações,” operated in areas inaccessible to trawls, and used more effective gear than trawling—extensive

nets whose effort was not captured by the simplified count of vessel trips. CPUE increased during the 5 years in which oceanic gillnet CPUE estimates were available (1993-1997), contradicting the trend in simple trawl CPUE. However, because the index of fishing effort used in this study (
i.e.,
vessel trips) does not account for possible changes in the length, duration, or mesh size of gillnets deployed, it is uncertain to what extent oceanic gillnet CPUE accurately reflects the abundance of
G. galeus
and
M. schmitti.
It is perhaps more notable that CPUE estimates of both the simple and pair trawl fisheries, while likely representing different shark species, show a similar pattern of severe decline following a peak in landings in the mid-1980s. These datasets suggest a broader collapse of elasmobranch fisheries in southern Brazil during this time.

There are also several anecdotal reports of fishery collapse and changes in fishermen behavior to adapt to the declining populations (Chiaramonte 1998; Barbini
et al.
2015; Irigoyen and Trobbiani 2016). For example, Chiaramonte (1998) noted that in the late 1990s, Necochea-based trawlers were forced to set gillnets further from the coast due to declining yields near shore. The fishermen allegedly attributed this to a movement of the tope shark population away from shore, but the author suggested that it was more likely an indication of declining abundance (Chiaramonte (1998)).

Taken together, the data described above show a generally consistent pattern of tope shark population decline in the 1990s resulting from intensive historical fisheries in the region. The best scientific and commercial information available provide no indication that the population has rebounded since falling to its lowest levels on record in the 1990s and early 2000s.

NE Pacific

Based on catch data in California from 1938 to 1944 (Ripley 1946), Holden (1977) roughly estimated an unexploited population size for the tope shark of 29,600 tons (~26,853 mt) (6.7 × 10
5
mature females). However, following the intensive fishery for
G. galeus
in the 1940s and 1950s, there appear to have been no other estimates of population size that could be compared to this baseline. Similar to other regions, we must instead rely on various qualitative accounts of the fishery, as well as sporadic catch data from fishery-independent and fishery-dependent sources gathered in the decades since to estimate relative population trends.

As fishing pressure rapidly intensified in the late 1930s and 1940s, sufficient resources were not available to quickly establish a system of fishing logs or thoroughly conduct interviews with the fishers at landing sites (Ripley 1946). However, available accounts from the time identified early signs of population depletion based on observations of the underlying fishery dynamics. Following the peak of the fishery in 1938-1939, when total shark landings in California ballooned by over tenfold to more than 4,000 mt per year, Ripley (1946) observed that landings began to decrease significantly despite increasing fishing effort. Comparing the December, January, and February landings of tope shark livers at the port of Seattle from 1943 to 1944, the FWS noted a 63 percent, 20 percent, and 70 percent decrease, respectively, despite observing that “fishermen had intensified their efforts and were using more gear” (FWS, April 10, 1944).

Ripley (1946) provided quantitative estimates of the tope shark population trend in this region based on CPUE in the gillnet fishery. Effort data was based on interviews with gillnet fishers in four regions spanning the coast of California and consisted of boat records from 489 fishing trips between 1942 and 1945. Dividing into the total number of tope sharks caught yielded a rough estimate of the average number of sharks taken by 1,000 fathoms (~1.8 km) of net fished for 20 hours. The data show a declining trend in CPUE for all four ports, which is particularly evident in Eureka (northern California), where data were collected for all 4 years. Ripley (1946) warned of several limitations with the data, including the relatively small sample size and inconsistency in the timing of the interviews with respect to the seasonal peak of the fishery (see also Roedel and Ripley 1950). However, he found “little doubt” that fishing success had declined from 1942-1943 to 1944-1945 and suggested that the trend observed in Eureka was likely representative of the tope shark population along the entire California coast (Ripley 1946).

Two years later, Barraclough (1948) reported a similar trend in British Columbia, with landings of tope shark livers rapidly declining from a peak of 27.9 mt in 1944 to 4.1 mt in 1946, concurrent with marked declines in two rough estimates of CPUE: (1) the average monthly catch of tope shark livers per boat, and (2) the average monthly catch per fishing trip per boat. Data were collected from the sunken gillnet fishery in Hecate Strait, and both metrics indicated a sharp decline from 1943 to 1946.

Landings continued to decline through the end of the 1940s, largely due to reduced fishing yields from the depleted tope shark population, but also in part due to the re-opening of international markets for other vitamin-bearing fish oils after the end of World War II, as well as the development of synthetic vitamin A alternatives, which substantially lowered demand (Roedel and Ripley 1950). As the fishery tailed off, species-specific data collection for
G. galeus
was largely discontinued. The State of California returned to the practice of reporting shark landings in aggregate until 1978, and while there are sporadic landings data for
G. galeus
in Oregon and Washington in the 1950s and 1960s (NMFS Office of Science and Technology), there is no information on fishing effort to accurately assess the species' relative abundance during this period.

Beginning in the late 1970s and 1980s, various Federal, State, and international monitoring programs were established to more thoroughly assess NE Pacific fisheries. Several of the resulting datasets include
G. galeus
catch statistics, which can be used to estimate more recent population trends. The West Coast Groundfish Bottom Trawl Survey began in 1977 and was streamlined in 2003 to conduct surveys annually from May to October along the U.S. West Coast. Generally, tope shark encounters in this survey have been quite rare, with eight being the most individuals recorded in a single year. The species is most commonly encountered in central California. There is some indication that catch rate increased briefly in this region in 2016-2018; however, after a suspension of the survey in 2019 and 2020, catch rate returned to relatively low levels in 2021-2023.

The International Pacific Halibut Commission (IPHC) conducts a Fisheries-Independent Setline Survey (FISS) to monitor halibut stocks in the NE Pacific. The FISS is conducted annually from May to September using bottom-set longline gear and covers a random subset of 1,890 sampling stations ranging primarily from northern California to the Bering Sea. The survey includes bycatch data starting in 1998 collected using two different sampling protocols: vessels counting bycatch for the whole longline haul and vessels counting bycatch on only the first 20 hooks of each 100-hook skate. Both subsets of data show tope shark CPUE to be highly variable over time. To assess population trend, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) applied a pair of generalized linear models (GLM) to each

portion of the data. They found that the mean number of tope sharks caught per sampling station did not change from 1998 to 2002 but then increased significantly from 2003 to 2018 (COSEWIC 2021). They also highlighted that tope shark observations have particularly increased in the waters east of Haida Gwaii, British Columbia. According to COSEWIC, the species was not recorded in this area between 1996 and 2005, despite substantial fishing effort (7,243 hours of trawl and 1,632 sets with hook and line gear) (COSEWIC 2021). However, since 2005, 295 tope sharks have been recorded by the FISS in this area. This is notable, as the area was heavily fished during the peak of the Canadian tope shark fishery in the 1940s, suggesting that population abundance in this region was once quite high (Barraclough 1948).

To expand the COSEWIC modeling analysis and incorporate the years since 2018, we applied a similar approach to assess population trend but modified the model framework in a few ways. For detailed information on model inputs, please see the Status Review Report. Model predictions indicate that population abundance has generally increased over the study period. The positive trend is consistent regardless of the method of model prediction. Moreover, the population trend varies according to latitude, corroborating the earlier observation by COSEWIC (2021). By plotting the modeled trend against Latitude along the x-axis, it is clear that the population trend is significantly greater at higher latitudes. There is also some indication that the population may be slightly declining in the middle of the survey distribution (~45° N). COSEWIC (2021) suggested that the disproportionate increase in British Columbia might reflect a northward movement of the population in response to warming waters. However, the history of this area as a prime fishing ground for tope sharks in the 1940s suggests that the species once occupied the area in great numbers. Therefore, we find it equally possible that the increase in CPUE is indicative of population growth.

Since 2002, tope sharks have also been recorded as a bycatch species in two fisheries observer programs that are jointly administered by NMFS and the Pacific States Marine Fisheries Commission. The West Coast Groundfish Observer Program (WCGOP) monitors at-sea bycatch discard rates for many of the commercial groundfish fishery sectors along the U.S. West Coast, including the Federally-managed limited-entry trawl fishery, several State-managed trawl fisheries, as well as various nearshore and pelagic fixed gear fisheries (
e.g.,
longlines, hand lines, fish pots/traps) (see Northwest Fisheries Science Center (NWFSC) 2024a for more information). The At-Sea Hake Observer Program (A-SHOP) monitors discard rates for the three components of the at-sea midwater trawl fishery targeting Pacific hake (whiting): the Mothership, Catcher-Processor, and Tribal sectors (see NWFSC (2024b) for more information). Both datasets provide limited insight into tope shark population trends, as discards are sporadic for most gear types. However, there is some indication in the bottom and midwater trawl fisheries, where tope sharks are most commonly encountered, that discard rate has generally increased since 2015 following a low period in the early 2010s. The trend is particularly apparent in the at-sea Pacific hake fishery north of 46.25° N (
i.e.,
waters off the coast of Washington). The WCGOP also records landings statistics for bycatch species, which combined with observed discards provides a rough estimate of total catch rate since 2002. Here, CPUE is calculated in terms of the total tope shark catch (
i.e.,
landed plus discarded weight) per vessel for each type of fishing gear. Tope sharks are encountered relatively infrequently in Oregon and Washington, mainly in the midwater trawl fisheries, and there is no discernible trend in CPUE. In California, similar to the discards-only data, total catch per vessel has generally increased since 2015 for each gear type where tope sharks are consistently encountered (
i.e.,
bottom trawl, bottom/midwater trawl, fixed gear, and non-trawl net gear fisheries). For vessels using non-trawl net gear in California, CPUE declined substantially from an average of 8.9 × 10
−2
mt per vessel per year in 2002-2006 to 9.1 × 10
−4
mt per vessel in 2013, before increasing again in subsequent years.

Logbook data from the State-managed gillnet fishery in California indicate that CPUE in the California gillnet fishery fluctuated around 0.5 individuals caught per vessel trip from 1981 to 2006. Based on the reported net length and soak time for each vessel trip where a tope shark was caught, we can roughly compare this value to the estimates reported by Ripley (1946). Average net length and soak time per vessel trip in the logbook dataset are approximately 603.3 fathoms (~1.1 km) and 29.5 hours, respectively. Thus, scaling to the unit of CPUE used by Ripley (1946), 0.5 individuals caught per vessel trip is roughly equivalent to 0.6 individuals caught in 1,000 fathoms (~1.8 km) of gillnet fished for 20 hours. That is approximately a 15- to 100-fold decrease in CPUE from 1942 to 1981-2021. It is important to note that the California Department of Fish and Wildlife (CDFW) cautions against using set-specific features (
e.g.,
net length, soak time) as the basis for CPUE calculations; however, broadly summarizing the data as above provides a rough indication of the scale of population reduction since the peak of the fishery in the early 1940s. From 2006 to 2013, CPUE declined substantially from 0.48 to 0.02 tope sharks caught per vessel trip and then generally increased from 2015 to 2021. Notably, by dividing the logbook dataset by month, it is clear that the annual CPUE during warmer months (May-August) declined significantly in 2008 and has remained relatively low in the years since, rebounding only slightly in recent years. By contrast, CPUE during cooler months (October-November) has increased substantially in 2018-2021 compared to prior years. The trends in CPUE, however, take place alongside several regulatory changes, which have gradually constrained the effort and location of gillnet fishing in California since the 1980s. This includes a series of depth- and area-based gillnet bans throughout central California in the late 1980s and 1990s (Forney
et al.
2001), a 1994 ban on gillnet fishing within 3 nautical miles (nm) of the California mainland and within 1 nm of the Channel Islands (CA Proposition 132), an emergency gillnet closure in 2000 and 2001 limiting the fishery to Federal waters south of Point Conception, and a permanent extension of the set gillnet ban in 2002 in all waters offshore of central California (from Point Reyes to Point Arguello) less than 60 fathoms (110 m) in depth (California Code of Regulations, Title 14, Section 104.1). As a result, the total effort in the California gillnet fishery has drastically declined since 1986, as gillnet fishing has largely been restricted to offshore waters in southern California. As discussed in
Range, Distribution, and Habitat Use,
tope sharks tend to migrate seasonally toward the poles in the summer and toward the equator or into deeper, offshore waters in the winter. Thus, the disproportionate increase in winter CPUE, as compared to summer CPUE, in recent years may be related to the concentration of gillnet fishing effort in the southern, offshore portion of the species' distribution in this region.

Since 1980, tope sharks have also been recorded by California commercial passenger vessel (CPFV) (
i.e.,
charter fishing) operators, who submit

mandatory logbooks to CDFW. Tope sharks have been reported only sporadically in northern California. In central and southern California, the species is encountered more consistently; however, there is not a clear long-term trend in CPUE, as it has fluctuated on an approximately 15-year frequency in both regions. Peaks in CPUE in the mid-1980s, around 2000 (in central California) or 2008 (in southern California), and in the mid-2010s are separated by periods of lower CPUE in intervening years. In both regions, CPUE peaked most recently in 2016 but has generally declined in the years since.

In sum, following the collapse of the North American tope shark fishery in the 1940s, observations of the species have been relatively rare in the NE Pacific. Throughout the majority of the last 4 decades, the species has been only sporadically encountered in the wide-ranging West Coast Groundfish Bottom Trawl Survey and by NMFS observers in various Federal and State-managed fisheries. In the California gillnet fishery, a rough comparison between the data presented by Ripley (1946) and logbook data from 1981-2021 reveals that tope shark CPUE is approximately 15- to 100-fold lower than it was during the peak of the fishery in the 1940s. However, it must be noted that the effort and location of the fishery has changed dramatically since the 1940s, which may skew recent estimates of CPUE. Two fisheries-independent surveys and several fisheries reporting databases provide insight into the recent population trend in the NE Pacific. With the exception of the CPFV logbooks, available datasets consistently show an increase in CPUE since 2016. In several datasets, such as the WCGOP and A-SHOP discards, and the California gillnet logbooks, this increase follows an inverse period of decline in the early 2010s. Thus, the extent to which this pattern may be part of a natural population cycle or may reflect changes in fishing behavior is not clear. Data from the fishery-independent IPHC FISS, which is the most statistically robust dataset available, suggest that CPUE has significantly increased since 1998, particularly in the northern portion of the species' distribution. Thus, while the population remains depleted compared to its unexploited level, there is consistency among datasets suggesting that the population is likely increasing to some degree.

SW Pacific

In the SW Pacific, tope shark populations in Australia and New Zealand are monitored and managed independently. Although tagging and genetic data indicate that some migration and interbreeding occurs between the two regions (see
Population Structure
), the rarity of trans-Tasman recaptures in tagging studies and the substantial geographic separation suggest that such movements are fairly infrequent. Most animals tend to stay within a home range of less than 500 km, in close proximity to local pupping and nursery areas (Hurst
et al.
1999; Walker
et al.
2020). Accordingly, given the separate management of tope sharks in Australia and New Zealand, available information on abundance and population trends is presented separately for the two countries.

Sustained harvest of tope sharks in Australia since the early 20th century has driven a significant long-term decline in population abundance (Davis
et al.
2024). Early signs of overexploitation date back to the 1940s, when both large, gravid female and juvenile tope sharks were heavily targeted in inshore nursery areas of southern Australia and Tasmania (Olsen 1959; Olsen 1984; Fowler
et al.
2005). Olsen (1959) reported declining juvenile abundance in two Tasmanian nurseries, which he attributed to the intense fishing pressure on both juveniles and gravid females during their pupping migration (see also Olsen 1984). He reported a sharp increase in fishing effort between 1944 and 1956 alongside a concurrent decline in mean body size and CPUE, warning that the fishery was showing “trends which are suggestive of depletion” and may follow the patterns of collapse observed in the NE Pacific unless stronger regulations were put in place (Olsen 1959). In 1991-1997, Stevens and West (1997) resurveyed several nursery areas in Tasmania and Victoria that were originally identified by Olsen. They found that catch rates were “much lower” at all sites and that pups may no longer be present at certain sites where they were once fairly common, such as in Georges Bay and D'Entrecasteaux Channel (Stevens and West 1997). During Olsen's original tagging program from 1947-1956, only 0.3 percent of the 1,170 juveniles tagged in Pittwater were recaptured at the same site. Stevens and West (1997) conducted a similar tag-recapture experiment in Upper Pittwater in 1996, and 18 percent of the 100 tagged juveniles were recaptured at the same site, a nearly 60-fold higher recapture rate. The authors interpreted this result as indication of reduced population abundance, although differences in site fidelity or dispersal behavior might also have played a role. While Olsen (1984) reportedly caught up to 80 juveniles per day in Pittwater by handline in the 1940s-1950s, Stevens and West (1997) were not able to catch a single tope shark in 23 hours of fishing in 1992 using the same methods and gear. Likewise, in Port Phillip Bay, Victoria, where Olsen could reportedly catch more than 200 juveniles and subadults per day in 1947-1951 (pers. comm., cited in Walker 1998), artisanal fishers caught fewer than 10 per day during a 3-year research study in the 1990s (Walker 1998). Moreover, demersal gillnet and longline surveys conducted in Bass Strait showed an 87 percent reduction in CPUE between 1973-1976 and 1998-2001 (Walker
et al.
2005).

In response to the observed population declines, the Australian government listed the tope shark as “conservation dependent” under the Environment Protection and Biodiversity Conservation (EPBC) Act in 2009. A formal Rebuilding Strategy was introduced in 2008 and updated in 2015. This strategy set a target to rebuild the stock to the limit reference point (
B
20
) within three generations (66 years) from 2008 (Davis
et al.
2024). Despite these measures, subsequent assessments have consistently shown that the population in Australia remains overfished (Davis
et al.
2024). One of the earliest formal stock assessments for the Australian tope shark fishery was developed by Punt and Walker (1998). Based on a spatially aggregated, age- and sex-structured model, estimates of adult biomass at the start of 1995 ranged from 13 percent to 45 percent of pre-exploitation levels, depending on model specifications. Punt
et al.
(2000a) suggested that age-1+ biomass (
B
1+
) at the start of 1997 was likely between 17 percent and 25 percent of pre-exploitation levels, while pup production was likely between 12 percent and 18 percent of pre-exploitation levels (discounting model scenarios that the authors deemed unrealistic). Thomson and Punt (2009) later updated the assessment model by incorporating fisheries-independent data from gillnet research surveys conducted between 1973 and 2008, along with several fisheries-dependent datasets. Model estimates suggested that
B
1+
at the start of 2007 ranged from 7 percent to 20 percent of pre-exploitation levels, while estimates of pup production ranged from 6 percent to 17 percent of pre-exploitation levels (Thomson and Punt 2010). Thomson and Punt (2009) found significant differences between models that assumed a single fishery stock in Australia versus those that assumed two. Specifically, the two-stock models

consistently provided a better fit to the data and estimated less depletion (
B
1+
:
14-20 percent pre-exploitation; pup production: 11-17 percent pre-exploitation) than one-stock models (
B
1+
:
7-9 percent pre-exploitation; pup production: 6-8 percent pre-exploitation).

In the past decade, fishery managers in Australia have transitioned away from CPUE-based stock assessment models toward a new framework based on close-kin mark-recapture (CKMR) analysis (Shark Resource Assessment Group (SharkRAG) 2011; Davis
et al.
2024). To apply the CKMR framework to the Australian tope shark population, Thomson
et al.
(2020) collected and genotyped over 2,400 individuals from across South Australia, Bass Strait, and Tasmania between 2010 and 2017. Their analysis yielded an estimate of approximately 50,000 mature individuals in the population in the early 2000s (Thomson
et al.
2020). This figure was three to four times lower than the abundance estimated by the conventional stock assessment model (Thomson 2012). Thomson
et al.
(2020) suggest that there are likely multiple overlapping biological stocks of tope sharks in Australia, perhaps structured according to different pupping grounds, which are differentially depleted (Thomson
et al.
2020). They also interpret the relatively small abundance estimate from the CKMR analysis as evidence that the immigration rate from the considerably larger tope shark population in New Zealand is limited and likely does not significantly influence local demographics; although Walker
et al.
(2020) suggested that migration from New Zealand may have helped stabilize the Australian population since the early 2000s.

Thomson
et al.
(2020) also generated projected population trends to the year 2037 by testing four rates of constant exploitation: zero catch, the 2016 catch rate, the 2017 catch rate, and the mean catch rate between 2013 and 2017. All four scenarios resulted in a modest upward trend in adult abundance, with estimated annual increases of approximately 1-11 percent depending on the exploitation scenario. However, the confidence intervals were very wide, and a declining trend could not be ruled out in any case. Based on the results of this analysis, SharkRAG adopted a fishery management strategy based on the mean 2013-17 catch rate scenario, which predicted a 3 percent average annual increase in population abundance (Davis
et al.
2024).

Recently, Thomson
et al.
(in prep) applied generalized linear modelling to updated CKMR data with roughly 3,000 additional tope shark samples collected between 2018 and 2023. Results of the modified GLM, accounting for ageing error and the triennial female reproductive cycle, indicate that adult abundance has increased approximately 7.5 percent (90 percent CI: 2.7 percent-12.3 percent) annually over the period 2006-2020. According to the authors, these results confirm the finding of Thomson
et al.
(2020) that tope sharks in the Southern and Eastern Scalefish and Shark Fishery (SESSF) are recovering. A full age-structured CKMR model, incorporating individual ageing error and fecundity-at-size effects, is under development and will be presented to SharkRAG in 2026.

Lastly, an analysis of CPUE in the trawl sector of the SESSF (1996-2020) provides additional insight into recent population trends in Australia. The data show a decline in catch rate from 1996 to 2003, consistent with the datasets used by Thomson and Punt (2009). After 2003, however, catch rate has increased steadily, reaching a level in 2020 that approaches or slightly exceeds that of 1996. Notably, unlike the gillnet fishery, where changes in fishing behavior towards greater avoidance have undermined the reliability of CPUE datasets, the trawl fishery is unlikely to have targeted tope sharks at any time and therefore provides a more consistent record of catch and effort (Tuck 2022). But Davis
et al.
(2024) caution that the trawl fishery accounts for only a small proportion of the total tope shark catch landed in southern Australia, and generally operates in locations different from those fished by the Gillnet, Hook, and Trap sector. Therefore, observed CPUE trends may not be representative of the broader Australian population.

There have been several efforts to establish a standardized CPUE index to estimate a population trend throughout New Zealand using available commercial fisheries data. The use of data from targeted set gillnet and bottom longline fisheries resulted in unreliable abundance indices due to sparse, inconsistent data and the potential for hyperstability (when CPUE remains artificially high despite an underlying decline in abundance, typically because fishers non-randomly target dense aggregations of the population) (Bradford 2001). Analysis of CPUE from bycatch fisheries by Ayers
et al.
(2006) revealed no consistent nationwide abundance trend but suggested a possible southward shift in distribution, possibly driven by warming sea temperatures. More recently, Fisheries New Zealand evaluated relative biomass indices in five spatial monitoring units that encompass the New Zealand exclusive economic zone (Fisheries New Zealand 2024b). As with the previous studies, although the tope shark population in New Zealand is assumed to be connected, Fisheries New Zealand was not able to establish a biomass index for the population as a whole. Therefore, monitoring units were delineated using boundaries that roughly correspond to gaps between where tope shark catch is concentrated (Dunn and Bian 2018; see Figure 3-32 in the Status Review Report). The biomass indices used in the assessments are based on CPUE data from inshore research trawl surveys as well as commercial set gillnet, bottom longline, and bottom trawl fisheries operating within each monitoring unit (Tremblay-Boyer 2021). The Inshore Fisheries Working Group (INSWG) determined which datasets to include in each regional biomass index based on the amount of data available and whether or not the data were judged to be reliable. Reference points (
e.g.,
biomass at MSY (
B
MSY
),
fishing mortality at MSY (
F
MSY
)) for relative biomass assessments were established for three of the five monitoring units based on reference periods when the catch rate was assumed to be sustainable. The INSWG then assigned qualitative likelihood scores to evaluate the status of each regional stock with respect to the reference points (
i.e.,
“Very Likely”: >90 percent probability; “Likely”: 60-90 percent probability; “About as Likely as Not”: 40-60 percent probability; “Unlikely”: 10-40 percent probability; “Very Unlikely”: <10 percent probability) (Fisheries New Zealand 2024b).

In the Far North region (N/1E), the biomass index derived from the combined set gillnet, bottom longline, and bottom trawl CPUE series has increased steadily since 1995, alongside an approximately 75 percent decrease in fishing effort. The INSWG found it likely that current biomass was at or above
B
MSY
. They also found it unlikely that biomass would decline at the current level of catch (Fisheries New Zealand 2024b). In the eastern North Island region (2/3N), none of the available CPUE data from set gillnet, bottom trawl, or bottom longline fisheries were accepted by the INSWG as indicative of population biomass, as there were conflicting trends in the data series that could not be explained. Furthermore, while there is some indication from the east coast South Island survey data that biomass was generally higher after 2007 compared to pre-1996, the survey almost exclusively

sampled juveniles and was therefore not considered as a suitable biomass index (Fisheries New Zealand 2024b). In the Lower South Island region (3S/5), the set gillnet CPUE dataset was accepted as a valid biomass index. The INSWG found it very likely that overfishing is occurring and about as likely as not that current catch levels will cause biomass to decline below 50 percent of the target
B
MSY
baseline. As compared to a
B
MSY
-compatible baseline established based on a period of relatively stable catch rates between 1989 and 1999 (assuming that the stock was not in a depleted state during this reference period), biomass has declined gradually as fishing intensity has increased (Fisheries New Zealand 2024b). In the Chatham Rise region (SCH 4), tope sharks are mainly caught in the bottom longline fishery, which was the only fishery in the region with sufficient data to be developed into a biomass index (Tremblay-Boyer 2021). Based on 16 years of available CPUE data, the biomass index has fluctuated without a discernible trend since 2003-2004 alongside a gradual increase in fishing intensity (Fisheries New Zealand 2024b). Because the dataset is relatively short and does not show any clear trends, the INSWG was not able to establish a reference baseline for the biomass index in this region. In the West Coast region (7/8/1W), the INSWG elected to use the WCSI research trawl survey, excluding the Tasman Bay and Golden Bay region, as the primary index of biomass. Based on this dataset, biomass declined from the late 1990s to 2000 and has largely fluctuated without a discernible trend in the years since. The INSWG established a target
B
MSY
baseline as the mean estimated biomass from 2005 to 2017, on the basis that biomass remained stable during this period while fishing intensity was “high and relatively stable” (Fisheries New Zealand 2024b). They concluded that the stock was about as likely as not to be at or above this reference baseline and about as likely as not to be experiencing overfishing at current catch levels (Fisheries New Zealand 2024b).

In June 2018, Fisheries New Zealand conducted a qualitative risk assessment for local chondrichthyan species, in accordance with the objectives of the country's National Plan of Action for Sharks (NPOA-Sharks, discussed further under Protective Efforts) (Ford
et al.
2018). Using 5 years of fishing data and knowledge of the species' biology, an expert panel evaluated the risk to each species from commercial fishing by scoring two factors on a scale of one to six: the intensity of the fishery and its consequence on the species' status. Fishing intensity for tope sharks was scored at the highest level, reflecting that “captures are locally to regionally high or continual and widespread.” The consequence of the fishery on the species' status was assessed as intermediate (3 out of 6), reflecting a “moderate and sustainable level of impact such as full exploitation rate,” but no indication that actual or potential impact is unsustainable.

Overall, although there is clear genetic and demographic connectivity between the Australian and New Zealand tope shark populations (see
Population Structure
), the low rate of trans-Tasman migration suggested by tagging and CKMR analyses indicates that the New Zealand population is unlikely to substantially influence the trajectory of the Australian stock. The tope shark population in Australian waters has experienced a significant, century-long decline due to high fishing pressure; however, population abundance is now increasing. Historical targeting of both mature females and juveniles in critical nursery areas led to early signs of depletion by the 1940s. Subsequent stock assessments confirmed the overfished status of the stock, with biomass estimated to have fallen to as low as 7-12 percent of pre-exploitation levels by the late 2000s. A formal rebuilding strategy has been in place since 2008 and recent analyses (fisheries independent and dependent) indicate that the stock is recovering. The New Zealand component of the population has sustained high levels of commercial catch for several decades without evidence of a similar, widespread collapse. While a single, nationwide biomass trend is unavailable, regional assessments present a mixed but generally more stable picture. The population status varies across different management areas, with some regions appearing stable or increasing while others show signs of localized depletion and are likely experiencing overfishing.

SE Pacific

A population abundance estimate and population trend data are not available for tope sharks in the SE Pacific region. Available landings data are limited for this region, and species-level assessments based on these data are hampered by species misidentifications and the practice of grouping shark landings under generic names—
e.g.,
“tollo” or “tiburon” (Sebastian
et al.
2008; López de la Lama
et al.
2018). Despite extensive fishing effort and targeted shark fisheries in the region, reported landings for tope sharks are low (Doherty
et al.
2014; Walker
et al.
2020), and no capture data are available in the FAO database. Given the extensive fishing effort in the region and the low reported catches, the species may not be abundant in the region. A trend analysis was not conducted for this region as part of the most recent IUCN assessment due to the limited data available (Walker
et al.
2020). Based on the available information, it is not possible to estimate the abundance and trends for tope sharks in the SE Pacific.

Distinct Population Segment Analysis

Section 3 of the ESA defines the term “species” to include “any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature” (16 U.S.C. 1532(16)). As mentioned above, the DPS Policy jointly established by FWS and NMFS in 1996 provides an interpretation of the term “distinct population segment” for purposes of listing, delisting, and reclassifying species under the ESA and outlines two elements that must be considered when determining whether a population of a vertebrate species qualifies as a DPS: (1) the discreteness of the population segment in relation to the remainder of the taxon to which it belongs; and (2) the significance of the population segment to the remainder of the taxon to which it belongs.

The petition expressly requested that if we find that there are DPSs of tope shark, we evaluate each of those DPSs for listing under the ESA. After initiating the status review, it became clear that the severity of threats and management measures differed across the species' range. As suggested by the IUCN's analyses, population trends also appeared to vary across the range. Given this information, the highly structured nature of tope shark populations, and the coincident discontinuity in the species' range, we elected to evaluate whether the regional populations of tope sharks qualified as DPSs pursuant to the DPS Policy.

Discreteness

The discreteness criterion of the DPS Policy may be satisfied if a population is markedly separated from other populations of the same taxon as a consequence of physical, physiological, ecological, or behavioral factors. Quantitative measures of genetic discontinuity may provide evidence of separation. International boundaries may also be used to delimit a distinct population segment if differences in the control of exploitation of the species, management of the species' habitat, the

conservation status, or regulatory mechanisms exist that are significant in light of section 4(a)(1)(D) of the ESA. As noted in the DPS Policy, absolute reproductive isolation is not required in order to recognize a distinct population segment, as this would be an impracticably stringent standard.

As discussed previously, the species' global distribution is discontinuous, with populations inhabiting temperate coastal zones separated by vast expanses of open ocean or by warm equatorial waters that coincide with gaps in the species' range. Tagging, telemetry, and observational data indicate fairly extensive migrations of tope sharks within most of the aforementioned regions but have not shown movement of individuals among regions, suggesting a lack of physical and demographic connectivity. Furthermore, as noted previously, multiple independent genetic studies using both mtDNA and nuclear microsatellites consistently reveal a high degree of genetic structuring among the major regional populations (Bester-van der Merwe
et al.
2017: F
CT
= 0.137, Φ
ST
= 0.895, p <0.05; Chabot and Allen 2009: Φ
ST
= 0.84, p <1 × 10
−6
; Chabot 2015: F
CT
= 0.15, p <0.001). These analyses show high and statistically significant pairwise measures of genetic differentiation, the presence of unique regional haplotypes, and extremely low estimates of inter-oceanic gene flow, confirming a long history of reproductive isolation. Collectively, and notwithstanding data gaps due to under- and non-sampled parts of the range, these studies indicate a regionally isolated population structure, with little to no contemporary connectivity between tope shark populations across major ocean basins or the equator. Thus, overall, and as discussed in further detail below, the best available scientific and commercial information demonstrates that the regional populations of tope sharks in the NE Atlantic, SW Atlantic, So. Africa, NE Pacific, SE Pacific, and SW Pacific (Australia/New Zealand) are markedly separated from each other, as evidenced by the best available genetic, tagging, and distribution data.

NE Atlantic

In the NE Atlantic, tope sharks are known to range from Iceland, the Faroe Islands, and Norway; throughout the Celtic and North Sea; south to the Bay of Biscayne, the Azores, the Canary Islands, and the northwestern coast of Africa; and into the Mediterranean Sea (Stevens 1990; Capapé
et al.
2005; Thorburn 2015; Colloca
et al.
2019; Thorburn
et al.
2019; Schaber
et al.
2022). Available tagging data gathered over many decades (~1959-2015) indicate that some tope sharks in the region tend to stay within a relatively small home range, others may undertake long-distance migrations of ~1,800 km to over 3,500 km away to other locations within the region (Holden and Horrod 1979; Stevens 1990; Little 1995; Fitzmaurice
et al.
2003; Colloca
et al.
2019; Thorburn
et al.
2019; Schaber
et al.
2022). No trans-equatorial movements have been recorded.

As noted previously, global genetic studies (Chabot and Allen 2009, Chabot 2015) also show a lack of population connectivity and a significant degree of genetic differentiation from other regional populations (Africa, South America, Australia, and North America). Thorburn
et al.
(2015) evaluated the genetic structure of tope sharks in the region using mtDNA and microsatellite samples from Ireland, Celtic Sea, southern North Sea, Isle of Wight, Channel Islands, Balearic Islands, Algeria, SW Scotland, Isle of Man, NW England, and Azores. All pairwise mtDNA Φ
ST
values (−0.0614-0.1936) and pairwise microsatellite F
ST
values (F
ST
= −0.0079-0.0192) were low and non-significant (p >0.05) (Thorburn
et al.
2015). Results of STRUCTURE analysis (testing k = 1-8 populations) also provided no evidence of population structure within the region. Although additional sampling in the eastern Mediterranean and other areas are needed, results from Thorburn
et al.
(2015) provide no evidence of population structure within the region, and in combination with the movement data, support a conclusion that tope sharks in the NE Atlantic comprise a single population.

So. Africa

Although there is some uncertainty regarding the exact range of this species within the So. Africa region, tope sharks are considered to range from southern Angola to East London, South Africa (Walker
et al.
2020; see Figure 2-2). Freer (1992) noted that tope sharks appear to be present throughout the area between Walvis Bay, Namibia and Cape Agulhas, South Africa. This population is physically separated from the NE Atlantic population by warm equatorial waters, which likely poses a thermal barrier to tope shark movements (Chabot and Allen 2009), and from other populations by ocean basins. Genetic analyses confirm this isolation, with studies by Bester-van der Merwe
et al.
(2017) and Chabot (2015) indicating high and significant genetic differentiation between tope sharks in So. Africa and those from the NE Atlantic, Australia/New Zealand, and South America. Several studies have also examined the population structure of tope sharks along the coast of South Africa and, in particular, across the transition zone between the southern Atlantic and southern Indian Oceans. However, the several studies investigating potential structuring within this region have found no significant genetic differentiation between the two ocean regions (Bester-van der Merwe
et al.
2017, Maduna
et al.
2017) and overall moderate to high gene flow within this portion of the South Africa coastline (Bitalo
et al.
2015, Bester-van der Merwe
et al.
2017, Maduna et al 2017).

NE Pacific

In the NE Pacific, tope sharks range from British Columbia, Canada, and southward to Baja California, Mexico, and into the Gulf of California (COSEWIC 2021). Tagging data show that some tope sharks in this region will undergo long-distance movements along the North American coast from Southern California to Baja California, Mexico, or to British Columbia, Canada (Herald and Ripley 1951, Nosal
et al.
2021), but no trans-equatorial or trans-Pacific movements have been documented. Available genetic data indicate that tope sharks sampled off the coast of southern California are genetically differentiated from those of So. Africa, NE Atlantic, Australia, and South America (Chabot and Allen 2009, Chabot 2015). In particular, results of genetic analyses using both microsatellite and mitochondrial data, indicate that tope sharks off southern California are genetically distinct from those off the coast of Peru (F
ST
= 0.09, p <0.001; mtF
ST
/Φ
ST
= 0.19/0.67, p <0.001; Chabot and Allen 2009, Chabot 2015). Estimated number of migrants per generation between regional populations was also low (Chabot and Allen 2009), and while the gene flow estimate from California to Peru was found to be higher (
i.e.,
0.257) relative to other comparisons, it was well below the estimated self-recruitment rates for each region (
i.e.,
0.998 and 0.692, Chabot 2015). While genetic data to explore potential populatio

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2026-07294. Public record. Not legal advice.