The leopard shark (''Triakis semifasciata'') is a species of houndshark, in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Triakidae. It is found along the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

coast of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, from the U.S. state of

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

Mazatlán Mazatlán () is a city in the Mexican list of states of Mexico, state of Sinaloa. The city serves as the municipal seat for the surrounding , known as the Mazatlán Municipality. It is located on the Pacific Ocean, Pacific coast across from th ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. Typically measuring long, this slender-bodied

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

is immediately identifiable by the striking pattern of black saddle-like markings and large spots over its back, from which it derives its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

. Large schools of leopard sharks are a common sight in bays and

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

, swimming over sandy or muddy flats or rock-strewn areas near kelp beds and

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

s. They are most common near the coast, in water less than deep. Active-swimming

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s, groups of leopard sharks often follow the

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

onto intertidal mudflats to forage for food, mainly

clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

s, spoon worms,

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

, and fish eggs. Most leopard sharks tend to remain within a particular area rather than undertaking long movements elsewhere, which has led to

genetic divergence Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes ( mutations) through time, often leading to reproductive isolation and continued mutation even after the populations h ...

between populations of sharks living in different regions. This species is aplacental viviparous, meaning that the young hatch inside the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

and are nourished by

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...

. From March to June, the female gives birth to as many as 37 young after a gestation period of 10–12 months. It is relatively slow-growing and takes many years to mature. Harmless to humans, the leopard shark is caught by commercial and recreational fisheries for food and the aquarium trade. This species is mostly fished in the waters off

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

where, after a period of population decline in the 1980s, new fishing regulations in the early 1990s reduced harvesting to sustainable levels. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

has assessed this species as of

Least Concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

, while noting that local

stocks Stocks are feet and hand restraining devices that were used as a form of corporal punishment and public humiliation. The use of stocks is seen as early as Ancient Greece, where they are described as being in use in Solon's law code. The law de ...

may easily become overfished because of the shark's slow growth and limited migratory habits.

Taxonomy and phylogeny

The first

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

applied to the leopard shark was ''Triakis californica'', coined by

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories and Crown Dependencies. * British national identity, the characteristics of British people and culture ...

zoologist Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...

John Edward Gray John Edward Gray (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for a z ...

in the 1851 ''List of the specimens of fish in the collection of the British Museum''. However, Gray did not furnish the name with a proper description, rendering it a ''

nomen nudum In Taxonomy (biology), taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published ...

''. In December 1854, American ichthyologist William Orville Ayres gave a lecture describing the species as ''Mustelus felis'', which included the first scientific description of the species. His lecture was reprinted first in ''The Pacific'', a

San Francisco San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...

newspaper, and then in the journal ''Proceedings of the California Academy of Natural Sciences''. In April 1855, French biologist Charles Frédéric Girard published another description of this species, naming it ''Triakis semifasciata''. Despite ''M. felis'' being the senior synonym, an error in recording the dates of publication resulted in the widespread use of ''T. semifasciata'' as the leopard shark's scientific name. As a result of this long-standing error, ''Triakis semifasciata'' came to be recognized as the valid name (as a '' nomen protectum'') and ''Mustelis felis'' was invalidated (as a '' nomen oblitum''). The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''semifasciata'' comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

words ("half") and ' ("banded"), describing this shark's dorsal pattern of saddle-like markings. In older literature, this species may be referred to as " tiger shark" or " catshark". The genus ''Triakis'' contains two

subgenera In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

, ''Triakis'' and ''Cazon''. The leopard shark is placed within the subgenus ''Triakis'' along with the banded houndshark (''T. (Triakis) scyllium''). A 2006

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis by J. Andrés López and colleagues, based on

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

-coding

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

s, revealed that ''Triakis'' and ''Cazon'' are in fact not closely related, and additionally that the leopard shark may be the most basal member of its family.

Distribution and habitat

The leopard shark occurs in the Northeastern Pacific Ocean, from the temperate continental waters of Coos Bay,

to the tropical waters of

, including the Gulf of California. It favors muddy or sandy flats within enclosed bays and

, and may also be encountered near kelp beds and rocky

s, or along the open coast. Numbers have been known to gather near discharges of warm effluent from

power plant A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the electricity generation, generation of electric power. Power stations are generally connected to an electr ...

s. Leopard sharks generally swim close to the bottom and are most abundant from the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

to a depth of , though they may be found as deep as . Many leopard sharks, particularly in the north, leave their coastal habitats in winter and return in early spring. A study in Tomales Bay in northern California determined that they depart when the water temperature drops below ; one tagged shark was found to have swum some south. While a few leopard sharks have been documented traveling hundreds of kilometers, most individuals tend to remain in a localized area for much of their lives. This low level of dispersal has led to

across its range. Seven discrete gene pools have been identified along the

n coast between

Humboldt Bay Humboldt Bay (Wiyot language, Wiyot: ''Wigi'') is a natural bay and a multi-basin, bar-built coastal lagoon located on the rugged North Coast (California), North Coast of California, entirely within Humboldt County, California, Humboldt County, ...

and

San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

. Of these, the Humboldt Bay subpopulation is perhaps the most isolated, with the sharks there maturing at a larger size and producing fewer offspring than those from other areas. By contrast, the area around

Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

represents a genetic transitional zone between subpopulations whose boundaries are more diffuse. Off

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

, the leopard sharks on the Pacific side are probably distinct from those in the northern Gulf of California. Although there is equivocal evidence for natal philopatry (returning to one's birthplace to breed) in this species, proximity to established breeding grounds likely contributes to the structuring of these different subpopulations.

Description

The leopard shark has a moderately stout body, with a short, rounded snout. There are well-developed, triangular flaps of skin in front of the nares. The eyes are large and oval, with a nictitating membrane (a protective third eyelid). The line of the mouth is strongly curved. There are furrows at the corners of the mouth extending onto both jaws, with those on the lower jaw almost long enough to meet at the midline. The tooth rows number 41–55 in the upper jaw and 34–45 in the lower jaw; each tooth has a slightly oblique, smooth-edged cusp in the center and 1–2 small cusplets on either side. These teeth are arranged into a flat, "pavement"-like surface with overlapping ridges.Delius, B
Biological Profiles: Leopard Shark
Florida Museum of Natural History Ichthyology Department. Retrieved on August 9, 2009. The large first dorsal fin is positioned about halfway between the pectoral and

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s; the second is almost as large as the first and much larger than the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

. The pectoral fins are wide and triangular. The lower lobe of the caudal fin is well-developed in adults but less than half the length of the upper lobe, which has a strong ventral notch near the tip. The coloration is unique, consisting of prominent black "saddles" and large black spots running along the back, on a silvery to bronzy gray background. Adult sharks often have more spots and saddles with lighter centers compared to juveniles. The underside is whitish and plain. The average length of a leopard shark is . Rarely males may grow to and females , and there is a record of an exceptional female that measured long. The heaviest known leopard shark weighed . Triakis semifasciata monterey.jpg, The dorsal color pattern of the leopard shark gives it its common name. Triakis semifasciata jaws.jpg, Jaws Triakis semifasciata lower teeth.jpg, Lower teeth

Biology and ecology

An active species that swims with a strong undulating motion, the leopard shark is commonly spotted cruising in or just beyond the surf zone. It is more active at night than during the day, and sometimes lies still on the bottom. In Tomales Bay (among other similar regions), the leopard shark follows the

onto

mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...

s to forage for food, retreating just fast enough to prevent being stranded or trapped as the water recedes. At Santa Catalina Island, resident sharks spend the day together in the shallows and at night, they disperse into deeper water, up to away.Manley, J.F. (1995). Diel movement patterns of leopard sharks, ''Triakis semifasciata'', at Santa Catalina Island, California. MS Thesis. California State University, Long Beach, CA. From birth, leopard sharks form large schools, generally segregated by age and sex; these groups may intermingle with

grey Grey (more frequent in British English) or gray (more frequent in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning that it has no chroma. It is the color of a cloud-covered s ...

or brown smoothhounds (''Mustelus californicus'' and ''M. henlei'') and spiny dogfish (''Squalus acanthias''). These schools are apparently nomadic, often appearing suddenly in an area for a few hours before vanishing just as quickly. In captivity, larger sharks have been observed establishing their dominance over smaller individuals via light nips to the pectoral fins. During summer days, large aggregations of mature females assemble in shallow bays and estuaries, dispersing at night. As these females follow the warmest patches of water (allowing them to raise their internal body temperatures by up to , they are speculated to be taking advantage of the heat to speed their own growth and that of their gestating young. The membership of these aggregations is inconstant, with individual females periodically switching between different sites scattered over several kilometers. Compared to the related grey and brown smoothhounds that share its range, the leopard shark has smaller and more numerous

red blood cell Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cel ...

s, allowing it to

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...

oxygen more efficiently. This may be an adaptation for foraging in deoxygenated estuarine environments.Martin, R.A
Estuaries: Leopard Shark
ReefQuest Centre for Shark Research. Retrieved on August 9, 2009. Their eyes contain very few

cone cell Cone cells or cones are photoreceptor cells in the retina of the vertebrate eye. Cones are active in daylight conditions and enable photopic vision, as opposed to rod cells, which are active in dim light and enable scotopic vision. Most v ...

s, likely due to the murky water they inhabit. Small leopard sharks fall prey to larger sharks such as the

great white shark The great white shark (''Carcharodon carcharias''), also known as the white shark, white pointer, or simply great white, is a species of large Lamniformes, mackerel shark which can be found in the coastal surface waters of all the major ocea ...

(''Carcharodon carcharias'') and the broadnose sevengill shark (''Notorynchus cepedianus''). On one occasion, a sevengill shark was seen ambushing a leopard shark on a tidal mudflat in

, striking with such momentum that the larger predator momentarily beached itself. Known parasites of this species include the tapeworms ''Phyllobothrium riseri'', ''Lacistorhynchus dollfusi'' and ''Paraorygmatobothrium barber'', as well as the

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s ''Echthrogaleus eoleoptratus'' and ''Achtheinus oblongatus''.

Feeding

The diet of the leopard shark consists of small

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

and littoral animals, most significantly

s ( Cancridae, Grapsidae, and Hippoidea),

(including anchovies, herring, topsmelt, croakers, surfperch,

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising over 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the fam ...

, rockfish, sculpins,

flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish Order (biology), suborder Pleuronectoidei, also called the Heterosomata. In many species, both eyes lie on one side of the head, one or the other migrating through or around ...

, and midshipmen), fish eggs,

s, and the echiurid fat innkeeper worm (''Urechis caupo''). This opportunistic hunter has also been known to eat ghost shrimp, polychaete worms, and the young of smoothhounds, shovelnose guitarfish (''Rhinobatos productus''), and bat rays (''Myliobatis californicus''). Eelgrass (''Zostera'') and

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

may be swallowed incidentally. The leopard shark captures prey by expanding its buccal cavity to create a suction force, which is facilitated by its labial

cartilage Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...

s swinging forward to form the mouth into a tube. Simultaneously, the shark protrudes its jaws forward to grip the prey between its teeth. As with other sharks, the teeth of the leopard shark are periodically shed and replaced; it takes 9–12 days for a replacement tooth to move into position. Leopard sharks have been caught with stomachs filled with clam siphons, which the sharks seize before the clams can retract and break off with a levering motion of their bodies. On occasion, the shark tears the entire clam body out of its shell this way. Other sharks examined have had stomachs containing whole innkeeper worms with no bite marks, suggesting that the sharks sucked them out of their burrows. Under a hollow bridge support in San Francisco Bay, a group of leopard sharks and spiny dogfish have been observed feeding on a dense school of anchovies by slowly swimming counterclockwise through the clockwise-swimming school, and swallowing any anchovies that accidentally entered their open mouths. In some places, this species feeds only on a few prey types and little else (e.g. innkeeper worms and cancrid crabs in Tomales Bay, jack silverside (''Atherinopsis californiensis'') eggs and the crabs '' Romaleon antennarium'' and '' Metacarcinus magister'' in Humboldt Bay). The predominant prey taken depends on location, time of year, and age. For example, in the Elkhorn Slough at

Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area. San Francisco itself is further north along the coast, by about 75 miles (120 km), accessible via California S ...

, cancrid crabs and innkeeper worms are mostly eaten in winter and spring, fish eggs from winter to early summer, bony fish in summer, and grapsid crabs and clams in fall. Young sharks feed mostly on crabs and transition to clam siphons, fish eggs, and innkeeper worms once they reach long. The largest sharks are the ones that consume the most fish.

Life history

The leopard shark is aplacental viviparous, with the developing

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

s sustained by a

yolk sac The yolk sac is a membranous wikt:sac, sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac' ...

until birth. In northern areas, females use bays and sloughs as nursery areas, while to the south they give birth in more open areas. Known breeding grounds along the coast of California include Humboldt Bay, Tomales Bay, Bodega Bay,

San Francisco Bay San Francisco Bay (Chochenyo language, Chochenyo: 'ommu) is a large tidal estuary in the United States, U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the cities of San Francisco, California, San ...

, Elkhorn Slough, Morro Bay, Santa Monica Bay (Los Angeles), Catalina Harbor (Santa Catalina Island), and San Diego Bay. Females give birth to 1–37 young annually from March and July (most in April or May), with the number of pups increasing with female size. Multiple males may father a litter from a single mother In Humboldt and San Francisco Bays, females drop their pups in beds of eelgrass that provide both shelter and food. In Catalina Harbor, females give birth on flats in of water, their backs and dorsal fins exposed; the pups stay in even shallower water less than deep. Mating occurs in early summer following birth; the only known observation of this in the wild was in 2004 off La Jolla, amongst nine sharks gathered from shore in water deep.Smith, S.E. (2004)
"Leopard Shark (''Triakis semifasciata'') Mating Activity Observed off La Jolla, California"
Southwest Fisheries Science Center, San Diego. Note. Newborn leopard sharks measure around long. Relatively slow-growing after the first 3–4 years of life, male leopard sharks grow an average of per year, reaching maturity at an age of 7–13 years and a length of , while females grow an average of per year, reaching maturity at an age of 10–15 years and a length of . Individuals of the same age can vary significantly in size and large sharks are especially slow-growing: one specimen was documented to have gained only in length over 12 years. The maximum lifespan of this species is estimated to be 30 years.

Human interactions

Wary and quick to flee, leopard sharks pose almost no danger to humans. There was only one recorded incident which was in 1955 of a leopard shark harassing a skin diver with a nosebleed, though no injuries resulted. This species is caught by commercial fisheries using

gillnet Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

s and longlines, and by recreational anglers and spearfishers; it is also caught as

bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

in bottom trawls. The meat is considered excellent eating and is sold fresh or frozen. However, leopard sharks living alongside human development may accumulate pollutants such as mercury,

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

s, and polychlorinated biphenyls (PCBs) within their bodies, and the California Department of Fish and Wildlife warns against eating them regularly. The leopard shark is prized by the aquarium trade for its attractive appearance and hardiness; this led to many newborn pups being captured with hook-and-line off southern California in the late 1980s and early 1990s. It may live for over 20 years in captivity. Most of the fishing for leopard sharks occurs in the waters off California, where commercial landings peaked at in 1983 and has averaged annually since 1991. These figures are believed to be underestimates, as an unknown portion of the leopard shark catch is recorded simply as "shark". In recent decades the number of sharks taken recreationally has exceeded those taken commercially, with sport fishers catching an average of 52,000 sharks per year from 1980 to 1988, and 45,000 sharks per year since 1993. This species contributes negligibly to fishery landings off Oregon. The status of leopard sharks off Mexico is uncertain, although Mexican shark fisheries tend to focus more on larger species. The

(IUCN) has assessed the leopard shark as of

. It is highly susceptible to local depletion due to its slow growth rate and low level of exchange between regional

. It was considered for, but is not managed under, the U.S. Pacific Fishery Management Council's (PMC) 1982 Groundfish Management Plan. In 1992, the State of California imposed a recreational minimum size limit of and a possession limit of three fish, a move that was strongly supported and promoted by the sport fishing community. In 1993, the State also instituted a minimum size limit of for the commercial harvesting of all sharks and rays, including for the aquarium trade. In addition, Californian restrictions on the use of certain types of fishing gear in near-shore waters confer good protection to this shark's core population. These management measures seem to have successfully reduced fishing mortality and halted the population decline from the 1980s; the status of the leopard shark off California is regarded as secure, with demographic models estimating an annual population increase of 3–6% with sustainable fishing.

References

Monterey Bay Aquarium Monterey Bay Aquarium is a Nonprofit organization, nonprofit public aquarium in Monterey, California. Known for its regional focus on the marine habitats of Monterey Bay, it was the first to exhibit a living kelp forest when it opened in Octob ...

* {{Good article

leopard shark The leopard shark (''Triakis semifasciata'') is a species of houndshark, in the family (biology), family Houndshark, Triakidae. It is found along the Pacific coast of North America, from the U.S. state of Oregon to Mazatlán in Mexico. Typically ...

Taxa named by Charles Frédéric Girard Viviparous fish Fish of the Gulf of California Fish of the Western United States Fauna of California Fauna of the Baja California Peninsula