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12 September 2002
Loughborough University researchers in co-operation with Aquatec Subsea Ltd are at the forefront of research to halt the decline in the world’s population of dolphins and porpoises.
Reports regarding the decline in these marine mammals have been causing increasing worldwide concern for many years, with recent reports highlighting problems in the South West of England and Scotland.
Dolphins and porpoises are known to respond to ultrasound, they use high frequency sounds to communicate and to hunt their prey.
However dangers such as static fishing nets are virtually undetectable to their sonar sense – and often have fatal consequences. Loughborough University’s Underwater Acoustic Research Group and Aquatec Subsea Ltd have developed AQUAmark, a series of high tech acoustic warning devices, which have now been shown in commercial fisheries to be very effective in saving marine mammal lives.
When activated by immersion in seawater, the AQUAmark pingers transmit a complex series of pre-programmed acoustic signals, comparable or less than the sound intensities produced by the marine mammals themselves. These signals act as a warning, repelling the mammals from fishing nets, and at close range can actively mask echoes from the fish they may be targeting with their sonar.
Dave Goodson, Chief Experimental Officer at Loughborough University, and part of the team working on AQUAmark commented, “Our aim has been to significantly reduce and if possible eliminate the risks to marine mammals of fishing nets.” He continued, “This is a significant problem that the fishing industry wants to solve but where traditional approaches have been ineffective. The digital technology we have developed is electro-acoustically very efficient and the randomly timed wideband warning signals we chose were selected only after detailed studies of porpoise and dolphin behaviour. AQUAmark is not only effective as a porpoise deterrent but offers a much longer operating life and includes management features which are not possible with analogue technology traditionally used in pingers introduced in the USA.”
One of AQUAmark’s biggest successes has been in Denmark where after very thorough testing new regulations were introduced two years ago that required this pinger to be used in the North Sea wreck net fishery for cod. So far the protection provided has been 100% successful and no porpoises have been killed in the nets equipped with AQUAmark devices. Further successful trials took place in the French Mediterranean in 2001 where an AQUAmark device adapted for use with dolphins produced an impressive reduction of 87.3% in the number of dolphins caught.
Recent press reports have focused on the large numbers of dolphin carcasses being washed up on the English Channel coastline, which are believed to be linked to pair-pelagic trawlers targeting sea bass. The Loughborough team, together with European partners from Holland, France, Denmark and Sweden, have investigated dolphin behaviour around pelagic trawls and found that dolphins and other small sea mammals are attracted to these nets, often deliberately swimming inside the mouth of the structure to prey on fish as they gather there.
As a result of these Loughborough studies, the Irish Sea Fisheries Board, commissioned the consultancy services of Loughborough University Enterprises Ltd. and Aquatec to develop a remotely controlled research tool to help solve a perceived problem in the Irish pair-pelagic fishery for Albacore tuna. Incidental catches of dolphins and porpoises can occur in this fishery, which operates along the continental shelf edge between Spain and Ireland.
The experimental system was recently delivered and the current trials are examining the effectiveness of this, together with the use of standard AQUAmark devices in this more difficult environment.
Andy Smerdon of Aquatec concludes, “We expect to continue our previous successes with this project, our development work is ongoing and working with Loughborough we now have the technology and the expertise to tackle new fishery/marine mammal interaction problems as they occur.”
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