External Organisations

  • Fjord & Bælt, Denmark

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The project includes four sub-projects that are all related to development of methods for mitigation of harbour porpoise bycatch. The first sub-project investigates the effective deterrent range for a commercial pinger and whether the range changes over time (habituation). This is important to know in order to be able to evaluate the effects if pingers are to be used in marine protected areas like the Natura 2000 areas. By deploying automated porpoise click loggers (C-PODs) in a grid around an active pinger, the effective range of the pinger will be assessed. The set-up will be deployed both in Denmark and in Scotland to also investigate possible regional differences in porpoise reactions to pingers. The second sub-project tests the alerting-hypothesis, i.e. whether it is possible to induce porpoises in the wild to use their biosonar against a target by having the target emit artificial porpoise click trains (alerting signals). Alerting signals have a number of advantages over traditional pinger signals, including that they will not lead to exclusion of porpoises from important habitats, that the risk of habituation is smaller because the porpoises will be able to learn from their experience with the alerting pingers, and that noise pollution will be considerably smaller because the sound level of alerting pingers is much lower than for traditional pingers. If this test of alerting signals is successful, the third sub-project will test if pingers emitting alerting-signals can reduce bycatch of harbour porpoises in the commercial gillnet fishery. Alerting pingers will be deployed on bottom-set gillnets in a suitable fishery, i.e. a fishery with a high bycatch rate, in a double-blind experiment. The fourth sub-project will investigate the behavior of free ranging harbour porpoises in relation to a gillnet. This includes land-based tracking by theodolite of porpoises approaching a bottom-set gillnet to determine detection distances and avoidance behavior, and will result in establishing a standardized method of assessing the detectability of commercial fishing gear by harbour porpoises.

The project is coordinated by DTU Aqua.
StatusCompleted
Period01/01/0931/12/11

Keywords

  • Research area: Fisheries Management
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ID: 2285593