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Leopard Shark (Triakis semifasciata) and Spotted Gully Shark (T. megalopterus) Fact Sheet: Population & Conservation Status

Leopard Shark (Triakis semifasciata) and Spotted Gully Shark (T. megalopterus) Fact Sheet

Population Status

Leopard shark

  • Population estimates
    • No estimates, but management practices have been effective in protecting leopard sharks (Smith and Horeczko 2008)
      • May be abundant where exploitation levels are low (Ebert et al. 2013)
    • Population trend: unknown (Carlisle et al. 2015)
    • “One of the most common nearshore sharks along the Pacific coast of North America” (Carlisle et al. 2015)
      • Most abundant along the coast of California (Ebert 2003)
  • Population structure
    • Proposed populations (Smith 2001; Barker et al. 2015)
      • Northern California
      • Southern California
      • Mexico, with Pacific and Gulf of California stocks possibly being distinct populations
    • Barker et al. (2015) found clear genetic differences between northern and southern California populations (north and south of Point Conception)
      • Lewallen et al. (2007) found more connectivity between leopard sharks in northern and southern California; suggested seven gene pools along coast of California
    • Additional genetic evidence needed to understand population structure in Mexico; there may be three regional population clusters, with limited genetic connectivity (Barker et al. 2015; Carlisle et al. 2015):

Spotted gully shark

  • Population estimates (Compagno 2009; Best et al. 2013; Ebert et al. 2013)
    • Uncommon to locally common (range is heavily fished)
    • Endemic to southern Africa
    • Limited to only a few specific habitat types (e.g., shallow rocky reef)
    • Population trend: decreasing (False Bay)
  • Population structure
    • Soekoe (2016) reports several populations as having female-biased sex ratios
    • Populations appear to have low-to-moderate genetic diversity (Soekoe 2016)
    • Maduna et al. (2017) found a homogeneous population structure (no subpopulations) along the coast of South Africa
    • Some evidence of genetic isolation between Atlantic and Indian Ocean populations, with the eastern cape of South Africa as a distinct population (Soekoe 2016)
      • Separation appears to be due to large-scale climate changes during the Pleistocene; lower sea levels resulted in loss of reef habitat

Conservation Status

Leopard shark

  • IUCN Status
    • Least Concern (2014 assessment) (Carlisle et al. 2015)
    • Past assessments
      • 2009: Least Concern
      • 2000: Lower Risk/conservation dependent (LR/cd)
  • CITES Status
    • Not listed (as of Oct 2018) (UNEP 2018)
  • Government laws and regulations

Spotted gully shark

  • IUCN Status
    • Near Threatened (2005 assessment) (Compagno 2009); assessment needs updating
      • This species may become threatened in the near future (Soekoe 2016)
    • Past assessments
      • 2000: Lower risk/near threatened (LR/nt)
  • CITES Status
    • Not listed (as of Oct 2018) (UNEP 2018)
  • Government laws and regulations
    • Considered a noncommercial species in South Africa (Booth et al. 2011), but is exploited by unregulated fisheries (Compagno 2009)

Threats to Survival

Leopard shark

  • Fishing pressures
    • Primarily taken by recreational fishers; nearly all U.S. harvest occurs in California (Smith and Horeczko 2008; Carlisle et al. 2015, except as noted)
      • Recreational fishing much more extensive than commercial fishing for this species
      • In recent decades, trend towards targeting leopard sharks for sport (considered “good fighters” on the line) (Love 1996)
      • Caught with baited hooks from piers, jetties, beaches, and boats; also by bowfishing, and spearfishing
    • Incidentally taken by commercial fisheries by gillnet, longline, and trawl; hook-and-line fishery in San Francisco Bay (Love 1996; Pondella and Allen 2008; Smith and Horeczko 2008; Carlisle et al. 2015)
      • Leopard sharks make up a small proportion of commercial landings; restrictions on gillnet fishing have reduced landings since the mid-1990s
    • Meat considered to be excellent quality (Love 1996; Ebert 2003)
      • Often sold in California fish markets (Castro 2011)
      • Older sharks may contain high levels of mercury (Ebert et al. 2013)
    • Stock history
      • Catch declined significantly during the 1980s and 1990s (Carlisle et al. 2007; Pondella and Allen 2008); peak catch in 1987 (Carlisle et al. 2015)
      • Recreational catch decreased from the mid-1990s to 2006—has remained lower and stable (Smith and Horeczko 2008; Carlisle et al. 2015)
    • Landings data in the 2010s do not suggest this species is at risk; however, populations may be impacted by overfishing and habitat loss due to location (large human population centers in California) and life history characteristics (slow growth, late maturation, few young) (Cailliet 1992; Kusher et al. 1992; Carlisle et al. 2015, except as noted)
      • Small sharks, pregnant females, and aggregating groups vulnerable
      • Aggregation behavior in shallow water, close to shore, makes leopard sharks vulnerable to over-exploitation (Nosal et al. 2013a)
    • Little known about leopard shark biology or fishing impacts in Mexico; not taken often in Mexico’s waters—no significant fishery (Carlisle et al. 2015)
  • Aquarium and pet trade industries
    • Poaching and trading, especially of pups, for sale in the cold-water aquarium trade (Carlisle et al. 2015)
      • The leopard shark’s striking coloration and hardiness has made it a popular aquarium species (Castro 2011)
      • An estimated 50,000-58,000 pups were poached from California from 1992-2003
    • Legally and illegally exported from California for display (Castro 2011)
    • Small leopard sharks sell for anywhere from $35 to hundreds of dollars each (Farrer 2009)
  • Habitat loss and degradation
    • Coastal bays and estuaries used as foraging and nursery areas (Carlisle et al. 2015)
    • Water quality concerns
      • Nutrient loading and eutrophication
      • Extremely low oxygen levels
      • Contaminants absorbed into tissues; impacts on health and reproduction unknown

Spotted gully shark

  • Vulnerable to exploitation (Best et al. 2013)
    • Exploited by unregulated shark fisheries (Compagno 2009)
    • This species cannot sustain recreational or commercial harvesting: has a small endemic range, low natural abundance, and life history traits which produce few young (Smale and Goosen 1999)
  • Fishing pressures (Best et al. 2013; Best and Attwood 2013)
    • Targeted by recreational anglers (Booth et al. 2011)
      • Commonly caught (Dicken et al. 2012)
      • If released, hooking and handling can still cause injury or death (Booth et al. 2011)
    • Southern Africa’s changing commercial fisheries
      • Sharks and rays increasingly targeted in response to declines of preferred bony fish species (Booth et al. 2011)
      • Stock declines in fish caught via line and rod-and-reel since the 1980s (Da Silva and Bürgener 2007)
        • Resulted in increases in shark exports from South Africa to Australia and Asia since the 1990s (Da Silva and Bürgener 2007)
          • Spotted gully sharks are part of this trade to a limited degree (Da Silva and Bürgener 2007)
    • Illegal commercial fishing
      • T. megalopterus legislated as a noncommercial species in South Africa (Booth et al. 2011), but “mistaken” for harvestable Mustelus species, which are more resilient to harvesting than Triakis species
        • See Identification
      • Longline fishery
        • Peak catch in the 1990s; catch declining (Best et al. 2013)
      • Illegal gillnet fishery (e.g., northeast False Bay, South Africa) (Best et al. 2013)
      • Also exploited by shore anglers in South Africa; harmful to the sharks’ feeding and growth, despite catch-and-release practices (Soekoe 2016)
    • Caught as bycatch in other commercial longline fisheries (centered in Gansbaai and False Bay, South Africa) (Compagno 2009)
      • Compagno (2009) states that spotted gully sharks make up a small proportion of the total catch

Management Actions

Leopard shark

  • Regulations
    • Minimum size and daily bag limits enacted by the California Department of Fish and Wildlife in 1992 appear to be protecting leopard sharks from excessive take/harvesting; leopard shark populations seem to be increasing as a result of these management actions (Carlisle et al. 2015)
      • “The recreational fishing sector not only strongly supported the move, but also did much to promote it” (Carlisle et al. 2015)
    • California Department of Fish and Wildlife Regulations for 2018 (Section 28.56)
      • Daily bag limit (3 per person) and size limit (minimum size 91.4 cm // 36 in TL) in effect
    • 1993: California Fish and Wildlife created a minimum size limit of 45.7 cm // 18 in TL) on the commercial sale of leopard sharks and all sharks and rays; helps to protect small sharks from illegal aquarium trade (Carlisle et al. 2015; Russo 2016)
    • 2002: California regulations related to gillnets and some other commercial fishing gear have also afforded leopard sharks protection (Smith and Horeczko 2008; Carlisle et al. 2015)
  • Monitoring and management plans
  • Marine protected areas
    • Establishing marine protected areas in locations where breeding females or pups aggregate may help prevent local over-exploitation; movements outside of marine protected areas reduce these benefits (da Silva et al. 2013; Nosal et al. 2013a; Nosal et al. 2014)
  • Community engagement and science-informed policy
    • Outreach needed to improve compliance with fishery regulations, especially in the prevention of illegal poaching of pups and pregnant females (Smith and Horeczko 2008)

Spotted gully shark

  • Fishing regulations
    • None
  • Government protections and scientific study
    • Maduna et al. (2017) investigate genetic markers which can be used to identify spotted gully shark specimens in South African fisheries

Conservation Success

Leopard shark along sandy seafloor; La Jolla

Management practices have been effective in protecting the leopard shark.

This female leopard shark at La Jolla Shores (San Diego, California) is also protected within the boundaries of the Matlahuayl State Marine Reserve, where any take is illegal.

Image credit: © Jeff Lemm, personal collection. All rights reserved. Used with permission from the artist.

Image location: La Jolla Shores, San Diego, California

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