We’ve already talked about one citrus shark -- the lemon shark (Negaprion brevirostris)… but there’s another lemon in the ocean. Meet the sicklefin lemon shark (Negaprion acutidens) which looks almost identical to the lemon shark! This stocky shark is also known as the sharptooth lemon shark, and can be distinguished from N. brevirostris by their pectoral fins, which are sickle-shaped (hence the common name).
We live of the ocean. We use it for food, we transport huge amounts of cargo across it, and every summer we head for the warm seas to dive, surf and fish. Therefore it’s important for us to know how healthy our ocean is.
Conventional methods mostly required we take large amounts of fish out and start counting them. The large problems with these were: everything we caught died. We got excellent measurements from them: we knew how big they grew at what life-stages; we knew how many were pregnant at what time of the year; we know how many species were around in the areas we caught. But all these methods were very destructive.
Then we developed methods whereby we dove down there and see things for our own eyes. Dive surveys became the conservation friendly survey method. However, divers could only go out in ideal weather situations, depth was limited to a maximum of 30 meters, and we found out that we were getting skewed results. The mere presence of the divers down there scared away some fish, while others were more curious and came from far around to investigate. We weren’t getting the right picture. Enter the Baited Remote Underwater Video (BRUV).
Sasha Whitmarsh and TFUI Founder Melissa met at a conference in Tasmania. They bonded over a mutual love of BRUVs -- Sasha worked with BRUVs and Melissa was fascinated by them.
Currently a PhD student at Flinders University in Australia, she took some time out of her busy schedule to answer some questions!
The Fins United Initiative: What is your project about?
Sasha Whitmarsh: We use BRUVS and similar video techniques for multiple projects within our lab. My PhD uses BRUVS to assess temporal changes in fish assemblages (e.g. between seasons and times of day), assess the potential influence of anthropogenic stressors and investigate ways to improve BRUVS itself as a method. We have another Honours project using BRUVS to assess the differences between pelagic and benthic fish assemblages, as well as a project using unbaited stereo video to measure the size of white sharks and other fishes at the Neptune Islands in South Australia.
TFUI Founder Melissa C. Marquez is author of all animal bios and "Behind the Fins" segments.
SEE MELISSA'S TEDx TALK HERE:
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