Blacknose Shark: Carcharhinus acronotus

Family: Carcharhinidae
Common name(s)

Blacknose Shark.

Identification

Small but stocky. Black/dark spot on tip of snout; distinct in young animals but often an indistinct smudge or absent in large adults. Pectoral fins relatively small. First dorsal origin level with free rear tip of pectoral fin. Second dorsal origin level with anal fin origin. No interdorsal ridge. Dorsal coloration pale yellowish-grey or light olive-grey. Body looks more bronzy in bright sunlight. Second dorsal, anal fin, and lower caudal lobe often dusky. Ventral surface white or cream coloured.

Size

Maximum length 141cm (Jose Castro). Size at maturity approx 100cm. Size at birth 31-50cm.

Habitat

A warm water species inhabiting coral reefs and sand flats/scrub.
0-64m. Often cited as occurring between 18-64m, but in the Bahamas I have consistently encountered blacknose sharks in shallow water (surface to 10m) where they are abundant.

Distribution

The blacknose shark is a tropical coastal species from the western Atlantic, Gulf of Mexico, and Caribbean Sea. It has been recorded from Virginia to Southern Brazil but rarely strays north of Wreck Island in North Carolina.

Blacknose Shark, Carcharhinus acronotus.

Conservation Status

ENDANGERED

The blacknose shark is heavily exploited in commercial shark fisheries along the US Atlantic coast and throughout the rest of its range. It is also a major bycatch component in the US shrimp trawl fishery in the Gulf of Mexico and along the Caribbean coast of South America.
In the Western Central Atlantic (USA and Mexico), blacknose shark populations have declined by 2.8% per year. In the last three generation lengths, the population as been reduced by 30-49%.
In Atlantic South America, it has undergone a population reduction of 50–79%.

In the USA, the National Marine Fisheries Service created the Atlantic Highly Migratory Species Federal Management Plan in 2006, which includes the management of blacknose sharks. However, the implementation of quotas (17.2 metric tons of blacknose sharks per year) and seasonal closures has done little to stem the decline of blacknose sharks in the US.
A variety of management plans, seasonal bans, and MPAs exist in Central America but they are poorly enforced.

Blacknose Shark, Carcharhinus acronotus.
Reproduction

A viviparous species with yolk-sac placenta. 1-8 pups per litter.
In South Carolina, mating takes place in early to mid June (Driggers 2002). Gestation in S. Carolina is 10-11 months. 9-10 months in the Gulf of Mexico (Sulikowski et al. 2007).

Diet

Diet consists mainly of small bony fishes.

Behavior

Blacknose sharks undergo seasonal migrations related to water temperature. They are know to perform agonistic displays (fins down, back hunched) when threatened.

Reaction to divers

Shy around scuba divers but surprisingly bold in baited situations.

Diving logistics

Near South Bimini Island in The Bahamas, blacknose sharks are often encountered during Caribbean reef shark feeds at Triangle Rocks and Southern stingray feeds at Gun Cay. The depth at both sites is less than 6m. These dives are only offered by land-based operators because most liveaboards are too large to approach those dive sites.

Andros Island is reputedly another good place in The Bahamas to find blacknose sharks; moving in and out of the mangroves with the tide. However, I did not encounter any when I was there.

Further south in the Caribbean in Sint Maarten, the reef shark feed organised by Dive Safaris (local operator) used to attract a handful of blacknose sharks but they became less frequent over time. It is unclear if they were fished out or if competition with the attending Caribbean Reef Sharks became too great.

Similar species

The blacknose shark’s small, stocky shape and black nose make misidentification in the field unlikely.