Welcome to the Marine Mammal and wildlife Research and Community Development Expedition blog where you can keep up to date with all the happenings and information from Kenya

Wednesday, January 4, 2012

A bit more on white tip reef sharks

One of the more exciting fish to snorkel with are sharks! During a recent snorkel on the southern side of Kisite Island we were lucky enough to swim with a white tip reef shark. White tip reef sharks can reach lengths of 2.1 metres, although adults rarely reach over 1.6 metres. This particular individual was about 1.5 metres. White tips are slender bodied sharks with a short blunt snout and, as their name suggests, brilliant white tips on both their dorsal and tail fin. During the day they can be found resting on the bottom of reefs. Unlike most sharks which have to swim continuously in order for water to pass over their gills, white tips open and close their mouths while resting. This causes water to pass over their gills allowing them to breathe without moving.

In the Cocos, it was found that during the day white tips are generally relaxed while at night they congregate in large numbers to feed, flushing out prey from the reef. Their main feeding choices are fish, octopus, lobsters and crabs. Despite the fearsome reputation of sharks, the shark we snorkeled with was very calm allowing us a fantastic viewing experience. In fact it is reported that white tip sharks are very curious and often approach divers, rarely attacking humans; although they can become dangerous especially when fish have been speared. Currently the white tip reef shark is not considered as endangered. However its limited habitat and depth range (shallow coral reefs), late maturity (they reach sexual maturity at around 8 years/ 1 meter in length), and increased fishing pressures mean that it may not be long until this shark is a threatened species.

There is no research being done at this time on reef sharks in Kenya, therefore all information is collected from other areas such as Australia and Costa Rica. In the last few weeks we have seen an apparent increase in the number of sharks seen near Kisite marine park, including species such as Tiger sharks, that were spotted feeding on a whale carcass just of the Upper Mpunguti island. Whether this increase in numbers is due to environmental, human induced causes or we were just lucky enough to have spotted more sharks is still to be determined.