Not Just Catching Rays in the Bahamas

The past three days have been an exhilarating cocktail of activities; long-line fishing for sharks, netting sting rays and catching and dissecting the hugely invasive lionfish!

Our long-line fishing gave a thrilling result as we caught two black-nose and one nurse shark reaching nearly two metres! Once caught the Sharks were anchored to the side of the boat with a rope around the head and the tail to reduce the stress experienced by the animal (this method is preferred to hauling the shark into the boat). We then took measurements of the body and fins, dart and fin tagged the shark and took biopsy samples for stable isotope analysis before setting the shark free.  Stable isotope analysis uses carbon and nitrogen isotopes to asses where and what the animal has been eating (short and long term) and helps link habitats together. It is a much more efficient, accurate and less invasive method than dissecting stomachs.

Lionfish are an incredibly invasive species in the Bahamas. With no natural predators and a reproductive rate of once every four days (compared to once a year in their native habitat) along with being resistant to most parasites, they are a very hard species to control! On our lionfish day we learnt about the culling programme being carried out by the Island School along with the “you slay, we pay” motive to encourage local fisherman to kill lionfish rather than the endangered grouper or conch species. We visited a few different coral patches and had the opportunity to net some lionfish for ourselves! Although we failed with the nets, a few were speared and brought back to the Island school for dissection. Helen and Freydis gave a fascinating talk about fish anatomy while dissecting, where we learnt how to tell a fish’s lifestyle by its tail shape and saw how massive the mouth of the lionfish is, making it able to eat a huge variety of species causing massive consequences for native reef species.

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Lionfish dissection. Photo: Dr Lucy Hawkes

Finally, we spent today participating in “Ray fit”! Sitting on the speed boat looking out for rays then launching into the water with three nets, wading through the sea to herd the sting ray into the nets and then bringing the net into shore make up the workout and I have to say, it’s exhausting! Although we were aching and tired this was my favourite day out of the three as we caught a heavily pregnant Southern Sting Ray and witnessed one of the first blood samples ever taken for this project. With all three Southern Sting Rays we caught we measured inner oscillation space (the space between the eyes which is unique for each species)  and body width/length along with dart and PIT tagging. Biopsy samples were taken from the dorsal fin and weight was recorded before we formed a human corridor for the ray to glide through into the ocean. Sting rays as a whole are incredibly data deficient and it was a privilege to watch how the CEI team are working towards expanding our understanding of these amazing creatures and appreciate how hard their work is.

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Heavily pregnant Southern Sting Ray. Photo: Lucy Twitcher

Overall it’s been a fantastic three days for everyone, we have learnt and experienced so much and are ready to begin our own projects over our final three days on #FieldBahamas!

vrb203    January 12th, 2016    Bahamas archive