Looking for Sharks at Glovers Reef

Shark Team

Demian Chapman from Nova Southeastern University ( http://www.nova.edu/ocean/ghri/) and Beth Backock from the Pew Institute of Ocean Science (http://www.pewoceanscience.org/projects/Glovers_Reef_/intro.php?ID=54) are back at Glovers Reef for their annual survey of Shark population. Helping them and also from the Pew Institute are Vera Agostini and Neil Hammerschlag.

Almost a full team, coming back to Middle Caye after setting the longline.

But the Shark group couldn't do their work without Norlan Lamb, the only boat captain to drive at night with sunglasses, Randolph Nunez and Ashbert Miranda, fishermen catching the bait for the longline.

The Shark group started their survey of the population of sharks at Glovers Reef in 2000. At the beginning their goal was to estimate and monitor the shark population. However their survey got more elaborate and they are now fitting transmitters in the sharks they catch. Once released they can follow the activities of the sharks to see how effective the no fishing reserve at Glovers is for these top predators.

Methods

The sharks are caught using longlining. A set of baited line hang perpendicular along a main floating line. The longline is checked every 3 hours to minimize the number of shark dying when caught. Where there is a shark on the line, the shark team measure it, tag it and if the shark is in shape they perform surgery to insert the radio transmitter.

Tagged Reef Shark

A few results

The most common sharks caught around glovers are nurse sharks (Ginglymostoma cirratum) and Caribbean Reef Sharks (Carcharinus perezi).

In a recent presentation Demian Chapman was careful when saying that unlike most other places in the world, the population of sharks around Glovers Reef is stable. Because sharks take a long time to mature and females only give birth to a few sharks, the impacts of overfishing are not immediately obvious. However the shark team did notice an extinction of lemon shark pup around Middle Caye and they believe that the few large lemon shark females that came to pup have recently been fished out.

Another observation was that these shark were not restricted to the no take zone of the marine reserve and that in fact some one of the reef shark was observed to travel all the way to Light House reef about 35 miles from Glovers.

The implication of these observation is that the marine reserve as it is is too small to provide protection for these top predators.

On the other hand the ban of longlining and gill net in a much wider region seems to be favourable for the shark population in this area.

Demian Chapman and his team are working towards elaborating management strategies to help protect the population around the work which are quickly declining.