Great White Shark News
Acoustic Tag Problems
Posted on Wednesday, 26 November 2014
Far Reaching Effects of Acoustic Tags
We recently came across this interesting article that highlights significant effects from the use of acoustic tagging. The fact that the seals seem to have honed in on these tags so readily does lead to the question of how much of a detrimental effect tags will have on a shark’s predation success rate. This is especially relevant to the Great White shark whose diet largely consists of seals.
Food for thought…
Ecologists’ attempts to track shoals of fish are being thwarted by seals which have learnt to recognise the sounds of their tagging devices. Grey seals are skewing the results of scientific studies because they swoop in and eat fish fitted with acoustic tags.
British biologists have now realised that electric tags fitted to large fish act as a ‘dinner bell’ to seals. They think the predators have learned that the low electronic noises emitted by the devices will lead them to a substantial meal. It could have a ‘profound effect’ on research studies designed to monitor behaviour and movements of fish, the scientists admitted.
Projects monitoring the movements of salmon and lingcod have already suffered disproportionate losses of juveniles and researchers now believe the tags could have been acting as homing beacons for hungry seals. They fear further research may be compromised unless a different type of tag is used, one that seals cannot hear.
Researchers at St Andrew’s and Cumbria universities issued their warning after carrying out a series of tests which demonstrated that seals can learn to use the tags to pinpoint a meal. Amanda Stansbury, of the University of St Andrew’s, said: ‘Seals can exploit new sounds such as fish tags and use them to their advantage. If the predators go after the tag it would skew the results.’