Bignose Shark

Carcharhinus altimus (Springer 1950)

Family Carcharhinidae (Requiem Sharks)

Identification: A large, heavy-bodied cylindrical shark with a long, wide, and bluntly pointed snout, prominent nasal flaps, a distinguishingly prominent interdorsal ridge, pectoral and dorsal fins that are long and straight; the inner corners are blackish in coloration. Teeth in the upper jaw are broad, triangular, and serrated, and number 14-16 for each side, while in the lower jaw they are narrow, triangular, serrated, and number 14-15 for each side. Coloration is gray to bronze on the dorsal surface, with a white ventral area, and no conspicuous markings.

Size: The maximum size recorded of this shark is three meters total length, with a weight up to 168kg. Size at birth is 70-90 cm total length.

Distribution: Eastern Pacific records of this species are sparse, but it ranges from Baja California to Central America. Elsewhere, it has a patchy, yet circumglobal distribution in subtropical and tropical waters.

Habitat: The bignose shark can be found offshore in deeper waters from 90 m to at least 430 m on the outer continental shelves and upper slopes. Younger sharks are found at shallower depths, up to 25m, while the older sharks are found at the deeper depths. These sharks have been caught at the surface over deep outer continental shelf waters suggesting that they at least on occasion migrate far off the bottom.

Biology: Bignose sharks exhibit a viviparous reproductive mode, with each pup having a yolk sac from which they nourish during development. Litter size ranges from 3-15 pups. These sharks give birth to their pups at different time throughout the year based on their location. Male size at maturity is 215 cm, and size at maturity for females it is 225 cm. In the Mediterranean Sea, the females give birth from August to September but off Madagascar the females give birth in September and October! Virtually nothing is known about their biology in the eastern North Pacific. Bony fishes, such as mackerels, soles, and batfish, are food sources, as well as cephalopods. In addition, smaller elasmobranchs such as dogfishes, catsharks, stingrays are preyed upon.

General Interest: Bignose sharks generally occur in deep waters offshore, and as such they rarely come into contact with humans, and thus are not considered a danger. They have not been evaluated for the IUCN Red List, but may be of concern as they are taken as bycatch of deep pelagic longlines and bottom trawls. In US Waters, the bignose shark is prohibited from capture in the commercial fishing industry, but is caught elsewhere, particularly in the Caribbean, and used for fishmeal and oil.

By Jennifer Bigman

Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039
jbigman@mlml.calstate.edu

Eastern Pacific Black Ghostshark

October 2009

Hydrolagus melanophasma

Family Chimaeridae

Identification: A chimaera of the genus Hydrolagus, which lack an anal fin, it has a fairly large, torpedo-like body, tapering from its blunt snout to a short whip-like tail filament. It has large, triangular pectoral fins, a long, slightly curved spine that precedes the first dorsal fin and a second dorsal fin that is of a uniform height throughout. Coloration is a uniform black with a lighter band across its snout, but has no other distinct markings or mottlings.

Size: A large-bodied chimaera with an observed maximum length of 110 cm (male); based on only a very few specimens. It may grow as a larger maximum size.

Distribution: Known from off southern California with observations occurring near the Channel Islands to the tip of Baja California and into the Gulf of California.

Habitat: A deep-water species it has been observed on Remote Operated Vehicle (ROV) dives by the Monterey Bay Aquarium Research Institute at depths between 1550 and 1670 meters. Documented collections of this species have been from 30.5 to 1400 meters. It has been observed from ROV video footage to occur over soft substrate with minimal to no rocky relief.

Biology: An oviparous species. Males mature at 92.6 cm total length, but little else is known of its biology. It has been observed on ROV video footage associating with congeners and with the longnose chimaera (Harriotta raleighana).

General interest: The species was first collected and recognized as being new to science by the late Carl L. Hubbs (Scripps Institute of Oceanography) in 1965. However, the species has only recently been described (James et al. 2009). It is caught in sablefish traps as bycatch and has on occasion been caught by hook and line by recreational anglers.

By Kelsey C. James

Pacific Shark Research Center

Moss Landing Marine Laboratories

8272 Moss Landing Road

Moss Landing, CA 95039

kjames@mlml.calstate.edu

Reference:

James, K.C., Ebert, D.A., Long, D.J., & Didier, D.A. 2009. A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific. Zootaxa 2218: 59-68.

Banded Guitarfish

September 2009

Zapteryx exasperata (Jordan & Gilbert, 1880)

Family Rhinobatidae (Guitarfishes)

Identification: A guitar-shaped ray with a broad disc that is about twice as wide as it is long. The dorsal surface is covered with numerous, small to large, scattered, stellate prickles and a single median row of enlarged thorns running along the mid-back. Coloration on the dorsal surface is a distinctive sandy brown to dark gray, with several prominent black bars, but lighter on the ventral surface.

Size: A moderate-sized guitarfish with females reaching a maximum total length of 97 cm and males a maximum length of 83 cm.

Distribution: This species ranges from southern California to at least Mazatlan, Mexico.

Habitat: A warm-temperate to tropical guitarfish species it is usually found on rocky reefs from the intertidal zone to a depth of 69 m.

Biology: A viviparous species with litters of 4 to 11 young, with the size at birth being between 15-22 cm. Males mature between 64-70 cm and females between 57-77 cm. mating takes place around March and birth takes place 3-4 months afterward, usually in July. Males and females appear to be highly segregated, with females tending to congregate in the shallower waters of bays and lagoons. The diet consists of crustaceans, including shrimps and crabs, and other benthic invertebrates. During the day they are usually found resting in caves or under ledges, but at night they become quite active as they forage for food.

General interest: Occasionally taken as by-catch by recreational and commercial fishers in southern California they are of no commercial importance, but in Mexican waters they are a commercially important species. These are relatively docile rays and may easily be approached by divers.

By David A. Ebert

Pacific Shark Research Center

Moss Landing Marine Laboratories

8272 Moss Landing Road

Moss Landing, CA 95039

debert@mlml.calstate.edu

August 2009

Bathyraja abyssicola (Gilbert, 1896)

Family Arhynchobatidae (softnose skates)

Identification: A softnose skate with a moderately triangular anterior disc margin, a broadly rounded posterior disc margin, and a disc width slightly greater than its length. Disc dorsal surface with 1-5 nuchal thorns separate from a row of 21 to 31 continuous median tail thorns and an interdorsal thorn. The two dorsal fins are similar in size and close set. Coloration is a uniform purplish gray above, occasionally with small dark blotches, ventral surface similar in color except for whitish areas around the mouth and anterior pelvic fins.

Size: A large species where females may reach up to 1.6 m in total length and males reach at least 1.35 m TL.

Distribution: This species ranges from northern Baja California, from off Coronado Island and Cortes Bank, north to the Bering Sea and as far west as Japan.

Habitat: Considered an uncommon skate video analysis from remote operated vehicles by researchers from the PSRC and the Monterey Bay Aquarium Research Institute have found this skate to actually be quite abundant at depth. Its preferred habitat appears to be on deepsea cobble and rocky reef substrate types. This is one of the deepest known skate species with a depth range of 350 to over 3,000 m.

Biology: The reproductive mode, as with all skates, is oviparous. Females mature at about 1.4 m TL and males between 1.1-1.2 m TL. The egg cases are large with longitudinal striations and an olive green color. Size at birth is large, about 20 cm TL. The deepsea skate is a voracious predator on benthic invertebrates including annelids, cephalopods, and crustaceans, and on benthic teleosts. Larger individual tend to feed on bony fishes in a higher proportion than smaller individuals that prefer invertebrates.

General interest: Occasionally taken as by-catch the preferred depth range and rugged habitat of this species precludes it from being taken in any substantive numbers as by-catch.

By David A. Ebert

Pacific Shark Research Center

Moss Landing Marine Laboratories

8272 Moss Landing Road

Moss Landing, CA 95039

debert@mlml.calstate.edu

July 2009

Pacific White Skate

Bathyraja spinosissima (Beebe & Tee-Van, 1941)

Family Arhynchobatidae (softnose skates)

Identification: A softnose skate with a disc that is slightly wider than long, broadly rounded pectoral fin apices, a disc surface evenly covered with numerous, small prickles above and below, giving it a shagreenlike texture to the touch. There are no enlarged thorns on the dorsal surface except for alar spines in adult males, but a single median row of tail thorns. The two dorsal fins are similar in size and lack an interdorsal thorn. The tail is slightly longer than the disc width. Coloration is a uniform pale salty gray above and below, with a dusky outer disc margin.

Size: A large species where females may reach up to 2 m in total length and males reach at least 1.5 m TL.

Distribution: This species ranges from Central America, and possibly the Galapagos Islands, to Waldport, Oregon, and possibly to the Sea of Okhotsk off northern Japan, although this may be a different species.

Habitat: Considered an extremely rare skate, known from only a few records, recent video analysis of remote operated vehicles by researchers from the PSRC and the Monterey Bay Aquarium Research Institute have found this skate to actually be quite abundant at depth. Its preferred habitat appears to be on deepsea boulder and rocky reef substrate type. This is one of the deepest known skate species with a depth range of 800 to over 3,000 m.

Biology: The reproductive mode, as with all skates, is oviparous. The egg cases are large with longitudinal striations and an olive green color. Size at birth is large, about 25 cm TL. What little is known about their diet indicates that they consume benthic fishes.

General interest: Occasionally taken as by-catch the preferred depth range and rugged habitat of this species precludes it from being taken in any substantive numbers as by-catch. NOTE: Given the rarity of this species if one should be captured it should be deposited into the fish collection at a major museum such as the California Academy of Sciences (Fish Collection Department) in San Francisco or you can contact us at the PSRC at the below address.

By David A. Ebert

Pacific Shark Research Center

Moss Landing Marine Laboratories

8272 Moss Landing Road

Moss Landing, CA 95039

debert@mlml.calstate.edu

GOLDEN COWNOSE RAY

RHINOPTERA STEINDACHNERI EVERMANN & JENKINS, 1892

FAMILY RHINOPTERIDAE (COWNOSE RAYS)

Identification: A diamond-shaped ray with a head distinctly protruding from the disc.  The anterior face of the cranium is concave with a bilobed subrostral fin.  Width of the disc is about 1.7-1.8 times its length.  The tail is extremely long and slender, about 1.2-1.6 times the disc length, with one or two rather small, serrated spines at the base.  Coloration is uniformly pale yellowish to brown dorsally, white ventrally.

Size: Maximum size is 105 cm disc width (DW) for females. Males are slightly smaller, with a maximum-recorded size of 96 cm DW.  Size records were derived from Bahía Almejas, on the Pacific coast of Baja California Sur, Mexico.  Specimens from the Gulf of California reach smaller maximum sizes (98 cm DW, females; 89 cm DW, males).

Distribution: This species ranges from Bahia de Sebastian Vizcaino, central Baja California, to the Gulf of California and south to Peru, including the Galapagos Islands. 

Habitat: This stingray inhabits nearshore and inshore waters to depths of approximately 30 m and can be found throughout the water column. It is usually associated with sandy substrates but also occurs near rock or coral reefs, often near the reef dropoffs. A transient, highly mobile species it often forms large schools or moves in loose aggregations. The movements of this stingray, like those of congeneric species, may be related to water temperature, as it tends to migrate northward in the Gulf of California during the spring and south in the autumn.

Biology: The reproductive mode of this species is aplacental viviparity. Females nourish young initially by means of a yolksac and later supplement this energy source with protein-rich uterine excretions termed hisotrophe. Only a single ovary is functional. Median size at 50% maturity for Gulf of California specimens is similar for females (70.2 cm DW) and males (69.9 cm DW). Fecundity is one offspring per female, with parturition estimated to occur from late June-August. Size at birth is estimated at 38-45 cm DW after a gestation period of approximately 11-12 months. Courtship and fertilization follow shortly after parturition. This species possesses plate-like teeth and appears to be primarily durophagous. Based on limited information, the diet consists of bivalves and tube-dwelling polychaetes. Individuals of this species from the Pacific coast of Baja California Sur reach greater maximum overall and embryo sizes than those from the Gulf of California.

General interest: This is one of the most abundant species landed in artisanal elasmobranch fisheries in Mexican North Pacific, where it is used for both food and bait. In this region, R. steindachneri is most frequently observed during summer months and is rare during winter. The large size at maturity, low fecundity, and schooling behavior of R. steindachneri indicate that this species could be particularly susceptible to overexploitation. A docile species that does well in captivity, this species and its congeners are often found in aquarium touch tanks and similar exhibits.

By Joseph J. Bizzarro
Pacific Shark Research Center
Moss Landing Marine Laboratories
8272 Moss Landing Road
Moss Landing, CA 95039
jbizzarro@mlml.calstate.edu

Pacific Starry Skate

Raja stellulata (Jordan & Gilbert, 1880)

FAMILY RAJIDAE (Hardnose Skates)

Identification: Known as the spiniest of eastern North Pacific hardnosed skates, the Pacific starry skate is covered with prickly spines and abrasive dermal denticles. Its dorsal surface has rows of thorns along its mid-back, groups of orbital thorns, up to six large thorns on its shoulder girdle, and a cluster of thorns along the edge of the pectoral fins or “wings”.  The number of these thorns increases with the size, and therefore the age, of the individual. In contrast, the belly is smooth and whitish, but with dark margins. The nose is very short, and two eyes spots are often visible above the pectoral wings. Its dorsal surface is brown to gray brown, providing effective camouflage on the seafloor however these colors fade upon death.

Size: Starry skates reach a reported maximum total length of 76 cm.

Distribution: Raja stellulata is commonly found from Oregon to Baja California at a depth range of 18-730m.

Habitat: Once commonly referred to as the rock skate, this species is known to live and hunt on rocky habitats.

Biology: Like the other skates, the starry skate is oviparous and lays its egg-cases (also called “mermaid’s purses”) on the seafloor.  Little is known about its reproductive biology, but males mature at about 67 cm and females at about 68 cm. Current investigations about their feeding habits confirm that the Pacific starry skate is a predator on species inhabiting rocky reefs, and may be at the top of the demersal food web along the California coast. It is known to eat rockfishes, poachers, and cephalopods. It also commonly feeds on shrimps and crabs.

General interest: These are harmless skates except for the numerous thorns that may inflict puncture wounds much like one might receive from handling a thorn bush. It is one of only a few skate species in the eastern North Pacific that does not appear to inhabit sandy bottoms, which explains why its diet shows such striking differences with the other local Rajids. With its limited distribution and its position as a top predator, this species is an apex predator in the nearshore food web along the West Coast of North America.

By Marie Cachera
Moss Landing Marine Laboratories
8272 Moss Landing Road
Moss Landing, CA 95039
mcachera@mlml.calstate.edu

Bentfin Devil Ray

Mobula thurstoni (Lloyd, 1908)

FAMILY MOBULIDAE (Manta and Devil Rays)

Identification: Like other Mobula species, the bentfin devil ray is recognized by its paired, flat head fins, large, angular pectoral disc, subterminal mouth with teeth in both jaws, and slender, “whip like” tail that has a single dorsal fin at the base and lacks a spine. In particular, the bentfin devil ray is moderate in size with short head fins, and a tail that is shorter than its disc width. Its disc has swept-back tips, which have a prominent double bend to their front. The underside of the disc is white centrally and silver on the pectoral fin tips. Above it is dark blue to black with a white tipped dorsal fin.

Size: Maximum size at least 190 cm, and possibly up to 220 cm, disc width (DW).

Distribution: A circumglobal species found in most all temperate and tropical seas. They are most common off Australia, Brazil, Chile, Costa Rica, Côte d’Ivoire, Ecuador, El Salvador, Eritrea, Guatemala, Honduras, India, Indonesia, Japan, Mexico, Nicaragua, Oman, Philippines, Senegal, South Africa, and Thailand.

Habitat: This mobulid species is found in pelagic, shallow, neritic waters from the nearshore down to about 100 m deep, in open and shallow temperate and tropical seas, often near coral reefs. They are found most commonly near the coast and usually at the surface, either singly or in small groups.

Biology: Viviparous with histotrophy (intrauterine milk) which nourishes the developing embryos. Litter size is usually one after a one to possibly three year gestation period. The neonates are born at about 65—85 cm DW. Males mature between 150—154 cm DW, but there is no information on the size at which females mature. They are filter-feeders, feeding mainly on planktonic crustaceans. Their head fins are used to direct prey into the their wide, “slot like” mouth and they have rows of fringed plates covering their internal gill slits to prevent small prey from escaping through their gill cavities.

General interest: The bentfin devil ray, known as the Mante Vampire in France, can leap several feet out of the water. They are listed by the IUCN as “Near Threatened” globally, but are considered “Vulnerable” throughout Southeast Asia. These rays are harvested and taken incidentally by gill nets, longlines, purse seines and harpoons. There is an increasing demand for their branchial filter plates, which are used in traditional Chinese medicines in Asia. Their skin, meat and cartilage are harvested for consumption. There is insufficient landings data for the bentfin devil ray due, in part, to the fact that they are often grouped with other Mobula species. They are vulnerable due to their low fecundity.

By Noëlle Yochum
Moss Landing Marine Laboratories
8272 Moss Landing Road
Moss Landing, CA 95039
nyochum@mlml.calstate.edu

LONGNOSE CATSHARK

APRISTURUS KAMPAE TAYLOR, 1972

FAMILY SCYLIORHINIDAE (CATSHARKS)

Identification: A small, moderately slender catshark with a long, broad snout, large gill slits, small eyes, lower labial furrows longer than upper, and a continuous supraorbital sensory canal. The first dorsal fin base is about equal in length to the second dorsal fin base with origin posterior to origin of pelvic fin. Second dorsal fin is broader and higher than first dorsal fin, originating posteriorly to origin of anal fin. Anal fin is short, very high and rounded with insertion anterior to second dorsal fin. Caudal fin is without crest of enlarged denticles on its upper margin. Color is a uniform blackish with prominent white posterior margins on precaudal fins.

Size: A maximum reported total length for males is 64.7 cm total length and for females it is 59.0 cm total length.

Distribution: Eastern North Pacific from Cape Blanco, Oregon, to central and southern California, USA and southward to the Gulf of California, Mexico.

Habitat: A deepwater, mainly bottom dwelling species found on the upper continental slope, ranging from 180 to 1888 m.

Biology: Oviparous, with a single egg case deposited per oviduct. Egg cases are typically thick-walled, measuring 6.1 to 7.1 cm in length, and lack tendrils. Embryos rely entirely on a yolk-sac during development. Newborns have two rows of enlarged denticles along their back that aid them in escaping from the egg case, which disappear shortly after birth. Size at birth is approximately 14 cm. Males usually mature at about 48 cm and females mature at about 49 cm total length. Diet consists of deepwater crustaceans (euphausiids and penaeid shrimps), cephalopods, and small bony fishes.

General interest: The longnose catshark is a poorly known species due to its deepwater habitat and confusion with other Apristurus species. Because this species is poorly studied, it is currently listed as data deficient (DD) by the IUCN. It is incidentally taken in deepwater trawls and sablefish traps off California. There have been reports of a similar or closely related species from off the Galapagos Islands, but this may in fact be an undescribed species.

By Jenny Kemper
Pacific Shark Research Center
Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039
jkemper@mlml.calstate.edu

BULL SHARK

CARCHARHINUS LEUCAS (VALENCIENNES, IN MÜLLER AND HENLE, 1839)

FAMILY CARCHARINIDAE (REQUIEM SHARKS)

Identification: A large, heavy set-bodied shark with a broad snout, relatively small eyes, a large, pointed first dorsal fin, and without an interdorsal ridge.The teeth are broadly triangular and serrated. The dorsal body coloration is a dusky gray that fades to white ventrally.

Size: The maximum reported size is 3.5 m and over 230 kg. Females reach a maximum length of 3.5 m and males 3.0 m. Females grow larger than males and average a length of 240 cm weighing 130 kg. Males have an average length of 225 cm weighing 95 kg. Size at birth ranges from 59-81 cm.

Distribution: The bull shark is found in many different parts of the world and can travel long distances. This shark is most common in subtropical coastal waters but can also be found in numerous river systems and in some lakes. They have been reported 3,700 km up the Amazon River and over 3,000 km up the Mississippi River. A bull shark population was thought at one time to be land locked in Lake Nicaragua, but after extensive research it was determined that they were able to reach the ocean through rivers and estuaries.

Habitat: The bull shark prefers shallow coastal waters less than 30 m deep. However, individuals have been located down to 150 m. This shark is commonly found in rivers, estuaries, and bays. This is the only shark species that is known to readily occur in freshwater systems. Young bull sharks live their early years in bays and estuaries until large enough to venture into the ocean. These sharks can also tolerate hypersaline waters up to 53 parts per thousand.

Biology: Bull sharks are viviparous with litter sizes ranging from 1-13 pups. The pups are nourished inside the mother for 10-11 months. Bays and estuaries are common nursery grounds. In warm water habitats, mating and birthing is year-round, but in cooler water areas birthing usually occurs during the summer months. Males reach maturity at about 192 cm and females about 205 cm at an age between 5 and 6 years, respectively. They prey on bony fishes, other sharks, rays, dolphins, turtles, birds, molluscs, echinoderms and crustaceans. Bull sharks have also been known to eat rats, hippos, dogs and even horses! This shark is primarily a solitary hunter that cruises the shallow water for any prey of suitable size. Bull sharks use the “bump and bite” technique of prey capture. The bump is an investigative technique that assists the shark in identifying prey.

General interest: The Bull shark is an aggressive shark as well as intensely territorial. It is considered to be one of the four most dangerous sharks, along with the white shark (Carcharodon carcharias), tiger shark (Galeocerdo cuvier), and oceanic whitetip (Carcharhinus longimanus), to humans. Numerous attacks by these sharks on humans have been reported from tropical regions. Its close proximity to populated shore lines and its aggressive behavior makes this shark extremely dangerous. In many countries the rivers that this animal frequents coincides with popular bathing and recreational areas. This creates more human interaction and thus more attacks. The greatest threat to this shark is from over-fishing. The meat is used for food and the hide is tanned for leather.

By Clinton Moran
Pacific Shark Research Center
Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039
cmoran@mlml.calstate.edu