Leopard shark
Encyclopedia
The leopard shark is a species of houndshark, family
Triakidae, found along the Pacific coast of North America
from the U.S. state
of Oregon
to Mazatlán
in Mexico
. Typically measuring 1.2–1.5 m (3.9–4.9 ft) long, this slender-bodied shark 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
. Large schools of leopard sharks are a common sight in bay
s and estuaries
, swimming over sandy or muddy flats or rock-strewn areas near kelp beds and reef
s. They are most common near the coast, in water less than 4 m (13.1 ft) deep.
Active-swimming predators, groups of leopard sharks often follow the tide
onto intertidal
mudflats to forage for food, mainly clam
s, spoon worm
s, crab
s, shrimp
, bony fish, 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
between populations of sharks living in different regions. This species is aplacental viviparous, meaning that the young hatch inside the uterus
and are nourished by yolk. 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
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 has assessed this species as of Least Concern
, while noting that local stocks
may easily become overfished
because of the shark's slow growth and limited migratory habits.
zoologist John Edward Gray
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 November 1854, French biologist Charles Frédéric Girard
published a description of this species as Triakis semifasciata, which was followed a month later by American ichthyologist William Orville Ayres
' description as Mustelis felis, both in the journal
Proceedings of the Academy of Natural Sciences of Philadelphia. The specific epithet semifasciata comes from the Latin
words semi ("half") and fasciatus ("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, Triakis and Cazon. The leopard shark is placed within the subgenus Triakis along with the banded houndshark
(T. (Triakis) scyllium). A 2006 phylogenetic analysis by J. Andrés López and colleagues, based on protein
-coding gene
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.
The leopard shark occurs in the cool to warm-temperate continental waters of the northeastern Pacific Ocean
, from Coos Bay
, Oregon to Mazatlán
, Mexico
, including the Gulf of California
. It favors muddy or sandy flats within enclosed bay
s and estuaries
, and may also be encountered near kelp
beds and rocky reef
s, or along the open coast. Numbers have been known to gather near discharges of warm effluent
from power plants. Leopard sharks generally swim close to the bottom and are most abundant from the intertidal zone
to a depth of 4 m (13.1 ft), though they may be found as deep as 91 m (298.6 ft). 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 10–12°C (50–54°F); one tagged shark was found to have swum some 140 km (87 mi) 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 genetic divergence
across its range. Seven discrete gene pool
s have been identified along the California
n coast between Humboldt Bay
and San Diego. 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
represents a genetic transitional zone between subpopulations whose boundaries are more diffuse. Off Baja California
, 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.
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.
The large first dorsal fin
is positioned about halfway between the pectoral and pelvic fins; the second is almost as large as the first and much larger than the anal fin. 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 1.2–1.5 m (3.9–4.9 ft). Rarely males may grow to 1.5 m (4.9 ft) and females 1.8 m (5.9 ft), and there is a record of an exceptional female that measured 2.1 m (6.9 ft) long. The heaviest known leopard shark weighed 18.4 kg (40.6 lb).
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 and elsewhere, the leopard shark follows the tide
onto mudflat
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 disperse into deeper water, ranging up to 10 km (6.2 mi) away.
From birth, leopard sharks form large schools generally segregated by age and sex, which may intermingle with grey or brown smoothhounds (Mustelus californicus and M. henlei) or spiny dogfish
(Squalus acanthias). These schools are apparently nomadic, often appearing suddenly in an area for a few hours and then 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 3°C (5.4°F), they are speculated to be taking advantage of the heat to speed their 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
s, allowing it to process
oxygen more efficiently. This may be an adaptation for foraging in deoxygenated estuary environments. Their eyes contain very few cone cell
s, likely due to the murky water they inhabit. Small leopard sharks fall prey to larger sharks such as the great white shark
(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 Humboldt Bay, 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
s Echthrogaleus eoleoptratus and Achtheinus oblongatus.
The diet of the leopard shark consists of small benthic and littoral
animals, most significantly crab
s (Cancridae
, Grapsidae
, and Hippoidea
), shrimp
, bony fish (including anchovies
, herring
, topsmelt, croakers
, surfperch, gobies
, rockfish
, sculpin
s, flatfish
, and midshipmen
), fish eggs
, clam
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 ray
s (Myliobatis californicus). Eelgrass
(Zostera) and algae
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
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 Cancer antennarius
and Cancer 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
, 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 70–80 cm (2.3–2.6 ft) long. The largest sharks are the ones that consume the most fish.
The leopard shark is aplacental viviparous, with the developing embryo
s sustained by a 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
, 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. 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 1 m (3.3 ft) of water, their backs and dorsal fins exposed; the pups stay in even shallower water less than 30 cm (11.8 in) 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 19 m (62.3 ft) from shore in water 0.3–3 m (0.984251968503937–9.8 ft) deep.
Newborn leopard sharks measure around 20 cm (7.9 in) long. Relatively slow-growing after the first 3–4 years of life, male leopard sharks grow an average of 2 cm (0.78740157480315 in) per year, reaching maturity at an age of 7–13 years and a length of 0.7–1.2 m (2.3–3.9 ft), while females grow an average of 2.3 cm (0.905511811023622 in) per year, reaching maturity at an age of 10–15 years and a length of 1.1–1.3 m (3.6–4.3 ft). 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 4 cm (1.6 in) in length over 12 years. The maximum lifespan of this species is estimated to be 30 years.
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Wary and quick to flee, leopard sharks pose almost no danger to humans. There is a single record from 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
s and longlines, and by recreational anglers
and spearfishers; it is also caught as bycatch
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
s, and polychlorinated biphenyl
s (PCBs) within their bodies, and the California Department of Fish and Game
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 45953 kg (101,309 lb) in 1983 and has averaged 14060 kg (30,997 lb) annually since 1991. These figures are believed to be under-estimates, 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 1980–1988, 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 International Union for Conservation of Nature (IUCN) has assessed the leopard shark as of Least Concern
. It is highly susceptible to local depletion due to its slow growth rate and low level of exchange between regional stocks
. 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 91 cm (35.8 in) 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 46 cm (18.1 in) 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.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Triakidae, found along the Pacific coast of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
from the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
to Mazatlán
Mazatlán
Mazatlán is a city in the Mexican state of Sinaloa; the surrounding municipio for which the city serves as the municipal seat is Mazatlán Municipality. It is located at on the Pacific coast, across from the southernmost tip of the Baja California peninsula.Mazatlán is a Nahuatl word meaning...
in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. Typically measuring 1.2–1.5 m (3.9–4.9 ft) long, this slender-bodied shark 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
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
. Large schools of leopard sharks are a common sight in bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s and estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, swimming over sandy or muddy flats or rock-strewn areas near kelp beds and reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s. They are most common near the coast, in water less than 4 m (13.1 ft) deep.
Active-swimming predators, groups of leopard sharks often follow the tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
onto intertidal
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
mudflats to forage for food, mainly clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, spoon worm
Echiura
The Echiura, or spoon worms, are a small group of marine animals. They are often considered to be a group of annelids, although they lack the segmented structure found in other members of that group, and so may also be treated as a separate phylum...
s, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, bony fish, and fish eggs
Roe
Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp, scallop and sea urchins...
. Most leopard sharks tend to remain within a particular area rather than undertaking long movements elsewhere, which has led to genetic divergence
Genetic divergence
Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes through time, often after the populations have become reproductively isolated for some period of time...
between populations of sharks living in different regions. This species is aplacental viviparous, meaning that the young hatch inside the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
and are nourished by yolk. From March to June, the female gives birth to as many as 37 young after a gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
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
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
and recreational fisheries
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
for food and the aquarium trade. This species is mostly fished in the waters off California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
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 has assessed this species as of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
, while noting that local stocks
Fish stock
Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters are the only significant factors in determining population dynamics, while extrinsic factors are considered to be insignificant.-The stock concept:All species have geographic limits to their...
may easily become overfished
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
because of the shark's slow growth and limited migratory habits.
Taxonomy and phylogeny
The first scientific name applied to the leopard shark was Triakis californica, coined by BritishBritish people
The British are citizens of the United Kingdom, of the Isle of Man, any of the Channel Islands, or of any of the British overseas territories, and their descendants...
zoologist John Edward Gray
John Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
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
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
. In November 1854, French biologist Charles Frédéric Girard
Charles Frédéric Girard
Charles Frédéric Girard was a French biologist specializing in ichthyology and herpetology.Born in Mulhouse, France, he studied at the College of Neuchâtel, Switzerland as a student of Louis Agassiz. In 1847, he accompanied Agassiz as his assistant to Harvard...
published a description of this species as Triakis semifasciata, which was followed a month later by American ichthyologist William Orville Ayres
William Orville Ayres
William Orville Ayres was an American physician and ichthyologist. Born in Connecticut, he studied to become a doctor at Yale University School of Medicine....
' description as Mustelis felis, both in the journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Proceedings of the Academy of Natural Sciences of Philadelphia. The specific epithet semifasciata comes from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
words semi ("half") and fasciatus ("banded"), describing this shark's dorsal pattern of saddle-like markings. In older literature, this species may be referred to as "tiger shark
Tiger shark
The tiger sharks, Galeocerdo cuvier, is a species of requiem shark and the only member of the genus Galeocerdo. Commonly known as sea tigers, tiger sharks are relatively large macropredators, capable of attaining a length of over . It is found in many tropical and temperate waters, and is...
" or "catshark
Catshark
Catsharks are ground sharks of the family Scyliorhinidae, with over 150 known species. While they are generally known as catsharks, many species are commonly called dogfish....
".
The genus Triakis contains two subgenera, Triakis and Cazon. The leopard shark is placed within the subgenus Triakis along with the banded houndshark
Banded houndshark
The banded houndshark is a species of houndshark, family Triakidae, common in the northwestern Pacific Ocean from the southern Russian Far East to Taiwan. Found on or near the bottom, it favors shallow coastal habitats with sandy or vegetated bottoms, and also enters brackish water. This shark...
(T. (Triakis) scyllium). A 2006 phylogenetic analysis by J. Andrés López and colleagues, based on protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
-coding gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s, revealed that Triakis and Cazon are in fact not closely related, and additionally that the leopard shark may be the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
member of its family.
Distribution and habitat
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, from Coos Bay
Coos Bay
Coos Bay is an S-shaped inlet where the Coos River enters the Pacific Ocean, approximately 10 miles long and two miles wide, on the Pacific Ocean coast of southwestern Oregon in the United States. The estuary is situated south of the Salmon River. The city of Coos Bay, once named Marshfield, was...
, Oregon to Mazatlán
Mazatlán
Mazatlán is a city in the Mexican state of Sinaloa; the surrounding municipio for which the city serves as the municipal seat is Mazatlán Municipality. It is located at on the Pacific coast, across from the southernmost tip of the Baja California peninsula.Mazatlán is a Nahuatl word meaning...
, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, including the Gulf of California
Gulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
. It favors muddy or sandy flats within enclosed bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s and estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, and may also be encountered near kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
beds and rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s, or along the open coast. Numbers have been known to gather near discharges of warm effluent
Effluent
Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...
from power plants. Leopard sharks generally swim close to the bottom and are most abundant from the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
to a depth of 4 m (13.1 ft), though they may be found as deep as 91 m (298.6 ft). Many leopard sharks, particularly in the north, leave their coastal habitats in winter and return in early spring. A study in Tomales Bay
Tomales Bay
Tomales Bay is a long narrow inlet of the Pacific Ocean in Marin County in northern California in the United States. It is approximately 15 miles long and averages nearly 1.0 miles wide, effectively separating the Point Reyes Peninsula from the mainland of Marin County. It is located...
in northern California determined that they depart when the water temperature drops below 10–12°C (50–54°F); one tagged shark was found to have swum some 140 km (87 mi) 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 genetic divergence
Genetic divergence
Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes through time, often after the populations have become reproductively isolated for some period of time...
across its range. Seven discrete gene pool
Gene pool
In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...
s have been identified along the California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
n coast between Humboldt Bay
Humboldt Bay
Humboldt Bay is a natural bay and a multi-basin, bar-built coastal lagoon located on the rugged North Coast of California, United States entirely within Humboldt County. The regional center and county seat of Eureka and the college town of Arcata adjoin the bay, which is the second largest enclosed...
and San Diego. 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 Ángeles
Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...
represents a genetic transitional zone between subpopulations whose boundaries are more diffuse. Off Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, 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
Nictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
(a protective third eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
). 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.
The large first dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
is positioned about halfway between the pectoral and pelvic fins; the second is almost as large as the first and much larger than the anal fin. 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 1.2–1.5 m (3.9–4.9 ft). Rarely males may grow to 1.5 m (4.9 ft) and females 1.8 m (5.9 ft), and there is a record of an exceptional female that measured 2.1 m (6.9 ft) long. The heaviest known leopard shark weighed 18.4 kg (40.6 lb).
Biology and ecology
Surf zone
As ocean surface waves come closer to shore they break, forming the foamy, bubbly surface we call surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves continue to move in, and they run up onto the sloping front of the beach, forming an uprush of...
. It is more active at night than during the day, and sometimes lies still on the bottom. In Tomales Bay and elsewhere, the leopard shark follows the tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
onto mudflat
Mudflat
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...
s to forage for food, retreating just fast enough to prevent being stranded or trapped as the water recedes. At Santa Catalina Island
Santa Catalina Island, California
Santa Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U.S. state of California. The island is long and across at its greatest width. The island is located about south-southwest of Los Angeles, California. The highest point on the island is...
, resident sharks spend the day together in the shallows and at night disperse into deeper water, ranging up to 10 km (6.2 mi) away.
From birth, leopard sharks form large schools generally segregated by age and sex, which may intermingle with grey or brown smoothhounds (Mustelus californicus and M. henlei) or spiny dogfish
Spiny dogfish
The spiny dogfish, spurdog, mud shark, or piked dogfish, Squalus acanthias, is one of the best known of the dogfish which are members of the family Squalidae in the order Squaliformes. While these common names may apply to several species, Squalus acanthias is distinguished by having two spines ...
(Squalus acanthias). These schools are apparently nomadic, often appearing suddenly in an area for a few hours and then 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 3°C (5.4°F), they are speculated to be taking advantage of the heat to speed their growth and that of their gestating
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
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 cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s, allowing it to process
Biological process
A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation....
oxygen more efficiently. This may be an adaptation for foraging in deoxygenated estuary environments. Their eyes contain very few cone cell
Cone cell
Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. If the retina is exposed to an intense visual stimulus, a negative afterimage will be...
s, likely due to the murky water they inhabit. Small leopard sharks fall prey to larger sharks such as the great white shark
Great white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...
(Carcharodon carcharias) and the broadnose sevengill shark
Broadnose sevengill shark
The broadnose sevengill shark is the only extant member of the genus Notorynchus, in the family Hexanchidae. It is recognizable because of its seven gill slits, while most shark species have five gill slits, with the exception of the members of the order Hexanchiformes and the sixgill sawshark.The...
(Notorynchus cepedianus). On one occasion, a sevengill shark was seen ambushing a leopard shark on a tidal mudflat in Humboldt Bay, 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
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s Echthrogaleus eoleoptratus and Achtheinus oblongatus.
Feeding
Littoral
The littoral zone is that part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes this intertidal zone and is often used to...
animals, most significantly crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s (Cancridae
Cancridae
Cancridae is a family of crabs. It comprises six extant genera, and eleven exclusively fossil genera, in two subfamilies:Cancrinae Latreille, 1802*Anatolikos Schweitzer & Feldmann, 2000*†Anisospinos Schweitzer & Feldmann, 2000...
, Grapsidae
Grapsidae
Grapsidae is a family of crabs known variously as marsh crabs, shore crabs or talon crabs. It is not confirmed that the family forms a monophyletic group and some taxa may belong in other families...
, and Hippoidea
Hippoidea
Hippoidea is a superfamily of decapod crustaceans known as sand crabs or mole crabs.-Ecology:Hippoids are adapted to burrowing into sandy beaches, a habit they share with raninid crabs, and the parallel evolution of the two groups is striking...
), shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, bony fish (including anchovies
Anchovy
Anchovies are a family of small, common salt-water forage fish. There are 144 species in 17 genera, found in the Atlantic, Indian, and Pacific Oceans. Anchovies are usually classified as an oily fish.-Description:...
, herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
, topsmelt, croakers
Sciaenidae
Sciaenidae is a family of fish commonly called drums, croakers, or hardheads for the repetitive throbbing or drumming sounds they make...
, surfperch, gobies
Goby
The gobies form the family Gobiidae, which is one of the largest families of fish, with more than 2,000 species in more than 200 genera. Most are relatively small, typically less than 10 cm in length...
, rockfish
Sebastidae
Sebastidae is a family of marine fish in the order Scorpaeniformes. Their common names include rockfishes, thornyheads and rockcods. Despite the latter name, they are not closely related to the cods in the genus Gadus, nor the rock cod, Lotella rhacina.Not all authorities recognise this family as...
, sculpin
Sculpin
A Sculpin is a fish that belongs to the order Scorpaeniformes, suborder Cottoidei and superfamily Cottoidea, that contains 11 families, 149 genera, and 756 species...
s, flatfish
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
, and midshipmen
Midshipman fish
The midshipman fishes are the genus Porichthys of toadfishes. They are distinguished by having photophores and four lateral lines...
), fish eggs
Roe
Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp, scallop and sea urchins...
, clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, and the echiurid
Echiura
The Echiura, or spoon worms, are a small group of marine animals. They are often considered to be a group of annelids, although they lack the segmented structure found in other members of that group, and so may also be treated as a separate phylum...
fat innkeeper worm (Urechis caupo). This opportunistic hunter has also been known to eat ghost shrimp
Thalassinidea
Thalassinidea is an infraorder of decapod crustaceans that live in burrows in muddy bottoms of the world's oceans. In Australian English, the littoral thalassinidean Trypaea australiensis is referred to as the yabby , frequently used as bait for estuarine fishing; elsewhere, however, they are...
, polychaete worms, and the young of smoothhounds, shovelnose guitarfish
Shovelnose guitarfish
The shovelnose guitarfish, Rhinobatos productus, is a ray that becomes sexually mature at an estimated seven to eight years. Males are between 90–100 cm, while females are around 99 cm at this time. The ray can live up to 11 years, and full grown sizes are around 120 cm for males,...
(Rhinobatos productus), and bat ray
Bat ray
The bat ray, Myliobatis californica, is an eagle ray found in muddy or sandy sloughs, estuaries and bays, kelp beds and rocky-bottomed shoreline in the eastern Pacific Ocean, between the Oregon coast and the Gulf of California. It is also found in the area around the Galápagos Islands. The largest...
s (Myliobatis californicus). Eelgrass
Zostera
Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass . The genus Zostera contains sixteen species.-Ecology:Zostera is found on sandy substrates or in estuaries submerged or partially floating...
(Zostera) and algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
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
Lip
Lips are a visible body part at the mouth of humans and many animals. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech...
cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
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 Cancer antennarius
Cancer antennarius
Romaleon antennarium, commonly known as the Pacific or California rock crab, is a crab of the genus Romaleon found on the western coast of North America.- Description :...
and Cancer magister in Humboldt Bay). The predominant prey taken depends on location, time of year, and age. For example, in the Elkhorn Slough
Elkhorn Slough
Elkhorn Slough is a tidal slough and estuary on Monterey Bay in Monterey County, California. The community of Moss Landing and the huge Moss Landing Power Plant are located at the mouth of the slough on the bay....
at Monterey Bay
Monterey Bay
Monterey Bay is a bay of the Pacific Ocean, along the central coast of California. The bay is south of San Francisco and San Jose, between the cities of Santa Cruz and Monterey....
, 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 70–80 cm (2.3–2.6 ft) long. The largest sharks are the ones that consume the most fish.
Life history
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s sustained by a yolk sac
Yolk sac
The yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
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
Bodega Bay
Bodega Bay is a shallow, rocky inlet of the Pacific Ocean on the coast of northern California in the United States. It is approximately across and is located approximately northwest of San Francisco and west of Santa Rosa...
, San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
, Elkhorn Slough, Morro Bay, Santa Monica Bay
Santa Monica Bay
Santa Monica Bay is a bight of the Pacific Ocean in southern California, United States. Its boundaries are slightly ambiguous, but it is generally considered to be the part of the Pacific within an imaginary line drawn between Point Dume, in Malibu, and the Palos Verdes Peninsula. Its eastern...
(Los Angeles), Catalina Harbor (Santa Catalina Island), and San Diego Bay
San Diego Bay
San Diego Bay is a natural harbor and deepwater port adjacent to San Diego, California. It is 12 mi/19 km long, 1 mi/1.6 km–3 mi/4.8 km wide...
.
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. 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 1 m (3.3 ft) of water, their backs and dorsal fins exposed; the pups stay in even shallower water less than 30 cm (11.8 in) deep. Mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
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 19 m (62.3 ft) from shore in water 0.3–3 m (0.984251968503937–9.8 ft) deep.
Newborn leopard sharks measure around 20 cm (7.9 in) long. Relatively slow-growing after the first 3–4 years of life, male leopard sharks grow an average of 2 cm (0.78740157480315 in) per year, reaching maturity at an age of 7–13 years and a length of 0.7–1.2 m (2.3–3.9 ft), while females grow an average of 2.3 cm (0.905511811023622 in) per year, reaching maturity at an age of 10–15 years and a length of 1.1–1.3 m (3.6–4.3 ft). 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 4 cm (1.6 in) in length over 12 years. The maximum lifespan of this species is estimated to be 30 years.
Human interactions
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
using gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s and longlines, and by recreational anglers
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
and spearfishers; it is also caught as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
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
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
such as mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
, pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s, and polychlorinated biphenyl
Polychlorinated biphenyl
Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...
s (PCBs) within their bodies, and the California Department of Fish and Game
California Department of Fish and Game
The California Department of Fish and Game is a department within the government of California, falling under its parent California Natural Resources Agency. The Department of Fish and Game manages and protects the state's diverse fish, wildlife, plant resources, and native habitats...
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 45953 kg (101,309 lb) in 1983 and has averaged 14060 kg (30,997 lb) annually since 1991. These figures are believed to be under-estimates, 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 1980–1988, 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 International Union for Conservation of Nature (IUCN) has assessed the leopard shark as of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
. It is highly susceptible to local depletion due to its slow growth rate and low level of exchange between regional stocks
Fish stock
Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters are the only significant factors in determining population dynamics, while extrinsic factors are considered to be insignificant.-The stock concept:All species have geographic limits to their...
. 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 91 cm (35.8 in) 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 46 cm (18.1 in) 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.