|Scientific Name:||Heterodontus francisci|
|Species Authority:||(Girard, 1855)|
Heterodontus californicus Herald, 1961
|Taxonomic Notes:||The literature suggests that this species may also occur off the coasts of Ecuador and Peru, but these records are unconfirmed and may have been misidentifications of another species.|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Reviewer/s:||Cavanagh, R.D. & Fowler, S.L. (Shark Red List Authority)|
Heterodontus francisci is a benthic shark, endemic to the warm temperate to subtropical waters on the Pacific continental shelf off Mexico and the US, and probably off Ecuador and Peru. This shark occurs from the intertidal zone to a depth of 152 m, although is most common at 2 to 11 m, moving offshore in the winter to waters >30 m. The species exhibits a high degree of segregation corresponding to its life history, with adults occurring shallower than juveniles. Horn sharks have a small home range and exhibit long term site fidelity. They are hardy species and can survive capture if returned to the water; however, catches in Mexico are sometimes left to die on beaches. They are of no commercial value, although they are taken as bycatch (primarily off Mexico). If the gillnet fishery in Mexico expands significantly in the future, the population could potentially face problems, however, insufficient information is available at present to assess Heterodontus francisci beyond Data Deficient. However, it could well be Least Concern in US waters where its capture in fisheries is extremely rare with no other apparent threats.
|Range Description:||In the US, it is most common off southern California but ranges to Monterey Bay and may occasionally penetrate as far north as San Francisco Bay (where it is not resident) during northern influxes of warm water (Compagno 2001). In Mexico, it occurs off Baja California, in the Gulf of California and slightly further south.|
Native:Mexico; United States (California)
|FAO Marine Fishing Areas:||
Present - origin uncertain:
Atlantic – eastern central; Atlantic – southeast
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Rare north of southern California. Occurs year-round in San Ignacio Lagoon, Mexico with lower abundance in summer and fall (Segura-Zarzosa et al. 1997). Differences in egg case morphology between the Channel Islands, California and the mainland suggest that they may be separate populations (Ebert 2003).|
|Habitat and Ecology:||
The horn shark is a common small warm temperate to subtropical benthic endemic shark. It is found on the continental shelf from the intertidal zone out to a depth of 152 m, although it is most common at a depth of 2 to 11 m. During the winter, horn sharks migrate into deeper waters, usually below 30 m. They exhibit a high degree of segregation corresponding to their life history. Adolescent sharks (between 35 to 48 cm) tend to remain in deeper water, usually between 40 to 150m, and as they mature they migrate back into relatively shallow water. This segregation of habitat by size and stage of maturity reduces competition for food and habitat between younger and older sharks. Habitat also changes ontogenetically, with juveniles inhabiting sandy bottoms with little vertical relief and adults inhabiting rocky reefs with caves and crevices, or areas of thick algae cover. Juveniles use bat ray Myliobatis californica feeding pits in sandy areas as shelter and foraging areas. Adults that occur in the algal habitat have noticeably longer fin spines than those in the reef habitat. This is due to their spines being worn down by going in and out of caves. Horn sharks show distinct diel patterns of activity, which is controlled by light intensity. Adults are relatively inactive diurnally, but are very active nocturnally. They are site specific, returning to the same resting place at dawn and remaining there until the evening. They have a small home range, usually no larger than 1,000 m², and they long-term site fidelity as sharks have been recovered in their tagging locations after up to 11.25 years at liberty. The furthest distance a horn shark has been documented as traveling is 16.3 km. Water temperature is an important factor controlling the relative abundance of the horn shark, as they prefer water over 70°F (Roedel and Ripley 1950, Nelson and Johnson 1970, Feder et al. 1974, Finstad and Nelson 1975, Strong 1989, Ebert 2003).
Horn sharks are oviparous, and females lay two eggs every 11 to 14 days usually between February and April, depositing up the 24 eggs in a single breeding season. Egg cases are usually laid in shallow water between 2 and 13 m deep. Development of embryos lasts 6 to 10 months, depending on temperature. Size at birth is 15 to 17 cm. Males mature at 56 to 61 cm and reach a maximum length of 83cm, while females over 58 cm are mature, with a maximum length of 96 cm, but possibly up to 120 cm. Very little is known about age and growth of this species. Growth rates are generally slow and very variable, and they do not correspond to size. The unconfirmed maximum age is 25 years (Roedel and Ripley 1950, Dempster and Herald 1961, Eschmeyer et al. 1983, Michael 1993, Compagno et al. 1995, Ebert 2003).
Horn sharks feed on a wide variety of benthic invertebrates and on small teleosts. Adults prey upon gastropods, crabs, shrimp, squid, sea urchins, sea stars, and small teleosts, namely the blacksmith Chromis punctipinna. Juveniles feed on polychaetes, small clams, and sea anemones in addition to opportunistically feeding on squid and small teleosts when available (Roedel and Ripley 1950, Feder et al. 1974, Strong 1989, Compagno 2001, Ebert 2003).
Life history parameters
Age at maturity (years): Unknown (male and female).
Size at maturity (total length): Female: >58 cm (Compagno et al. 1995); Male: 56 to 61 cm (Strong 1989).
Longevity: 25 years (unconfirmed) (Michael 1993).
Maximum size (total length): Female: 96 cm, possibly up to 120 cm; Male: 83 cm (Roedel and Ripley 1950, Feder et al. 1974).
Size at birth : 15 to 17 cm (Compagno et al. 1995, Ebert 2003).
Average reproductive age (years): Unknown.
Gestation time: 6 to 10 months (Dempster and Herald 1961, Ebert 2003).
Reproductive periodicity: Unknown.
Average annual fecundity or litter size: 24 eggs in a single breeding season (Ebert 2003).
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
In California horn sharks are of no commercial value. They are taken as bycatch in traps and trawls and occasionally by recreational anglers. In Mexico they are caught as a bycatch of the shrimp fishery and other bottom-trawling operations. Caught as bycatch in the demersal gillnet fishery in the northern Gulf of Mexico and likely on the Pacific side of Baja California during the winter and spring. The Mexican population could have problems in the future if the gillnet fishery expands (Wade Smith, pers comm). They have been captured by divers for sport and for the large fin spines, which are made into jewellery; decreases in numbers of horn sharks have been noted in areas with intense diver activity in Southern California. Horn sharks are often harassed and grabbed by divers, but when provoked may swim after their assailants and bite them. These sharks are kept in many public aquaria in the US. They are hardy, attractive, readily maintained, will breed in captivity, and have been displayed for many years (Compagno 2001, Ebert 2003).
Captured as bycatch, large sharks are eaten, but smaller ones are discarded. They have also been captured by divers for sport and for the large fin spines, which are made into jewellery. Also utilized (non-consumptive) for display in public aquaria in the US. In Mexico these sharks are probably utilized (or formerly utilized) for fishmeal.
Like other hornsharks, Heterodontus francisci is a hardy species and can survive capture in drift and trawl nets. Individuals should be returned to the water if alive after capture.
Further information on distribution, population structure and biology is required.
The development and/or implementation of National Shark Plans under the FAO IPOA-Sharks, where necessary.
|Citation:||Carlisle, A.B. 2006. Heterodontus francisci. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 08 December 2013.|
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