PRIZE TIME RESULTS! Last Friday we asked you all what our recent hydroacoustic echogram taken recently in Little Cayman was showing? We had a lot of great suggestions, thanks for all your entries! What the echogram is showing, as you can see in this image here, is a spawning aggregation of Nassau grouper being surveyed by divers. More specifically, you can see the top of a reef spur, with a large school of aggregating fish, Cayman Islands Department of Environment and REEF Reef Environmental Education Foundation researchers documenting the activity, and their bubbles rising to the surface as they swim across the reef alongside the aggregating fish (being careful not to swim into the aggregation and disturb the fish). The hydroacoustic method works by an echosounder firing a ping of sound down through the water column, this ping is then reflected of fish, the seabed (and divers and their bubbles). The strength of the returning ping can be used to determine the size and location of the fish. The different colours relate to the strength of the echoes with darker reds showing the strongest return through to greens then blues showing weaker. The purpose of this research is to document the use of Caymans spawning aggregation sites to assess whether they are being sufficiently protected according to their use by different species of fish. By comparing the acoustic data on fish abundance with that of the divers, we can estimate the amount of fish in areas that are difficult to dive, particularly our deeper SPAG sites. This is being done as a major part of the DOEs current Darwin Post-project multi-species monitoring of Caymans spawning aggregation areas, looking at, 1) which species of fish use our known SPAGs for reproduction, and 2) where is the larvae taken by currents and where are the new young fish likely to end up. This hydroacoustic work has been conducted by Jack Egerton who is conducting research here as part of his PhD work at Bangor University, School of Ocean Sciences and has been funded as part of our Darwin Initiative Post-project grant from the UKs Department for Environment, Food and Rural Affairs. Our project partners also include REEF, The Nature Conservancy, and with additional generous sponsorship from the Guy Harvey Ocean Foundation. The winner of this competition is Hal Lewis Peterson, just minutes before William Goodwin! Well done Hal! We will contact you to discuss collection of your prize. Stay tuned for more fun facts, news, and prize giveaways.
Posted on: Mon, 03 Mar 2014 16:02:46 +0000
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