Sharptooth Lemon Shark, Sicklefin Lemon Shark.
A large bodied shark with a short, rounded snout. Dorsal fins somewhat falcate with pointed tips. Second dorsal fin almost as large as first dorsal. Dorsal coloration yellowish-brown, or olive-brown. Ventral coloration white or cream. Black spot on snout tip. Fins may have dusky tips and posterior margins.
Maximum length 310cm. Size at birth 45-80cm.
Tropical/sub-tropical. Narrowtooth lemon sharks inhabit shallow coral reefs (within lagoons and around offshore reefs) and sand flats. Also found in mangrove estuaries. From the intertidal zone to at least 30m.
The narrowtooth lemon shark is found in most coastal areas of the tropical Indian Ocean, Southeast Asia, tropical Australia, and the islands of the central Pacific.
GLOBALLY VULNERABLE, REGIONALLY ENDANGERED
The narrowtooth lemon shark exhibits very limited movement patterns. Within Australian waters, this species is wide-ranging and captured in small numbers in gillnets, beachmeshing and longlines on the east coast and Northern Territory. Catches in Western Australia are also small. In Australia, there are likely to be significant areas of unfished habitat outside the operational ranges of these fisheries, thus the population is assessed as Least Concern. Outside Australia, this species is heavily fished in unregulated and expanding inshore fisheries throughout its range, and this, together with its narrow habitat range and limited potential for recolonisation of heavily fished sites, leads to a global assessment of VULNERABLE. Further, in Indonesia there has been little recent evidence of this species at fish markets although it was historically abundant. Widespread damage and destruction of coral reefs and mangrove habitats in parts of South East Asia are also cause for concern. In addition there are records of local extinctions in India and Thailand. This species is assessed as ENDANGERED in South East Asia.
Citations and References
Pillans, R. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Negaprion acutidens. The IUCN Red List of Threatened Species 2003: e.T41836A10576957. https://dx.doi.org/10.2305/IUCN.UK.2003.RLTS.T41836A10576957.en. Downloaded on 06 October 2020.
A viviparous species with yolk-sac placenta. Up to 14 pups per litter. Gestation is approximately 10-11 months. Mating takes place biennially.
Lemon sharks mostly eat bony reef fishes and sharks and rays.
Narrowtooth lemon sharks have a great degree of site fidelity. In an 1984 study, Stevens tagged and released 143 lemons at 43 sites. Of the 19 sharks that were recaptured later in the study, 91% were within 2km of their previous location.
Reaction to divers
Usually shy around divers unless baited.
Sharptooth lemon sharks are occasionally seen at sites throughout their range, but the majority of sightings (by divers) take place around remote islands in the south or central Pacific.
In Fiji’s Beqa Lagoon, baited dives often attract lemon sharks. The feeds are dominated by aggressive bull sharks but the lemons sometimes mix with them or are seen at other sites in the area.
Previously, baited dives in French Polynesia presented excellent opportunities to get close to sharptooth lemons, but shark feeds have now been banned throughout the country. However, due to their site fidelity, lemons are still seen at sites where the feeds took place in Bora Bora, Moorea, and Tahiti.
Sharptooth lemons are also regularly seen by snorkelers, on the reefs surrounding Heron Island on the east coast of Australia.
Lemon Shark Extremely similar but this species range does not overlap with the sharptooth lemon shark. It can be distinguished by its more rounded fin tips, and lack of black spot on the tip of its snout.
Sandtiger Shark Similar coloration and fin sizes but easily distinguished by its pointed snout and permanently exposed pointed teeth.