Marine mammal bycatch

Marine mammals can be divided into two groups in UK waters: whales, dolphins and porpoises (collectively known as cetaceans) and seals (pinnipeds).

 

Very little data exists on the bycatch of seals in UK waters, but bycatch deaths are thought to be in the low hundreds per year. In a recent study, 2% of tagged seals were killed in fishing gear, mainly gill and tangle nets. The impact of this bycatch level on the seal population is not thought to be significant.

 

In contrast, cetaceans are one of the more high profile victims of accidental capture in fishing nets. It was estimated that hundreds of thousands of cetaceans are killed globally each year through entanglement in fishing gear. In European waters, there have been a number of studies of such incidental bycatch. These, though not complete or comprehensive, indicate that the bycatch of cetaceans is widespread, and may threaten the integrity of dolphin and porpoise populations. Such concerns lead to JNCC working with DETR (now Defra) to develop a UK Small Cetacean Bycatch Response Strategy which was published in 2003. This strategy identified measures to reduce small cetacean bycatch to a level below that set as unacceptable by ASCOBANS in 2000 (1.7% of the best population estimate). Subsequently, EC Regulation 812/2004 came into force which required monitoring of cetacean bycatch and the use of acoustic deterrents in specified fisheries and areas. The UK Bycatch Monitoring Programme was formally initiated in 2005.

 

Since Regulation 812/2004 came into force, for three years running (2005-2008 inclusive) there have been no observations of cetacean bycatch in any of the fleet segments listed for compulsory monitoring. This is not to suggest that UK fisheries do not have a bycatch of any cetaceans, but rather that the segments being statutorily observed under the regulation have very low bycatch rates and are thus unlikely to be at a level that are a conservation threat.

 

Additional monitoring of pelagic trawl and static net fisheries was also undertaken for the purposes of Article 12 under the Habitats Directive and ‘Scientific Studies’ under Regulation 812/2004. Between 2005 and 2006, approximately 460-730 harbour porpoises and 410-610 short-beaked common dolphins were bycaught in the Celtic and Irish Sea areas (ICES sub area VII) whilst in 2007 the estimate was 206-1699 harbour porpoises and 29-440 short-beaked common dolphins. For 2008, the bycatch estimates of harbour porpoise in gillnet and tanglenet fisheries in the Irish and Celtic Sea areas was 498-1409 and for common dolphins 279-1019. The bycatch levels recorded are below 1.7% of the best population estimate and unlikely to represent a major conservation threat to either species. However, there are bycatches in many other European fisheries affecting the same biological populations, and it is not yet possible to determine the cumulative significance of the various estimates available at this time.

 

What has become clear over the four years during UK monitoring under EC Regulation 812/2004 is that inappropriate fisheries segments are being targeted for compulsory monitoring. Other Member States have made similar findings. A review of the fleets that are currently being sampled was undertaken in the first quarter of 2009. It was recommended that future coverage should include tanglenet, setnet and gillnet fisheries deployed from vessels <15m as well as demersal trawl fisheries. The European Commission have yet to decide whether to implement these recommendations.

 

JNCC participates through involvement on the UK Bycatch Monitoring Programme Steering group at the UK level while at the international level JNCC experts have been involved in European Commission groups and the ICES Study Group for Bycatch of Protected Species.

 

 

 

 

ASCOBANS, 1997. Cetacean by-catch issues in the ASCOBANS area. Unpublished report of the ASCOBANS advisory committee working group on by-catch. 23pp.

 

Barlow, J. & Cameron, G.A., 2003. Field experiments show that acoustic pingers reduce marine mammal bycatch in the Californian drift gill net fishery. Marine Mammal Science, 19, 265-283.

 

Berrow, S.D., O'Neill, M. & Brogan, D., 1998.Discarding practices and marine mammal by-catch in the Celtic Sea herring fishery. Biology and Environment Proceedings of the Royal Irish Academy, 98B, 1-8.

 

Berrow, S.D., Tregenza, N.J.C. & Hammond, P.S., 1994. Marine mammal bycatch on the Celtic shelf. DG XIV/C/1 study contract 92/3503.

 

Berggren, P., Wade, P.R., Carlstrom, J. & Read, A.J., 2002. Potential limits to anthropogenic mortality for harbour porpoises in the Baltic region. Biological Conservation, 103, 313-322.

 

Cox, T.M., Read, A.J., Swanner, D., Urian, K. & Waples, D., 2004. Behavoural responses of bottlenose dolphins, Tursiops truncatus, to gillnets and acoustic alarms. Biological Conservation, 115, 203-212.

 

Cox, T.M., Read, A.J., Solow, A. & Tregenza, N., 2001. Will harbour porpoises (Phocoea phocoena) habituate to pingers? Journal of cetacean Research and Management, 3, 81-86.

 

Dawson, S.M., ead, A. & Slooten, E., 1998. Pinger, porpoises and power: uncertainities with using pingers to reduce bycatch of small cetaceans. Biological Conservation, 84, 141-146.

 

House of Commons Environment, Food and Rural Affairs Committee, 2004. Caught in the net: by-catch of dolphins and porpoises off the UK coast. Third Report of Session 2003–04.48pp.

 

ICES, 2008. Report of the Study Group for Bycatch of Protected Species (SGBYC), January 29-31 2008, Copenhagen Denmark. ICES CM 2008/ACOM: 48. 80 pp.

 

Kuiken, T., Simpson, V.R., Allchin, C.R., Bennett, P.M., Codd, G.A., Harris, E.A., Howes, G.J., Kennedy, S., Kirkwood, J.K., Law, R.J., Merrett, N.R. & Phillips, S., 1994. Mass mortality of common dolphins (Delphinus delphis) in south west England due to the incidental capture in fishing gear. The Veterinary Record, 134, 81-89.

 

Lopez, A., Pierce, G.J., Santos, M.B., Gracia, J. & Guerra, A., 2003. Fishery by-catches of marine mammals in Galician waters: results from on-board observations and an interview survey of fishermen. Biological Conservation, 111, 25-40.

 

Morizur, Y., Berrow, S.D., Tregenza, N.J.C., Couperus, A.S. & Pouvreau, S., 1999. Incidental catches of marine mammals in pelagic trawl fisheries of the northeast Atlantic. Fisheries Research, 41, 297-307.

 

Northridge, S., Kingston, A., Thomas, L. and Mackay, A. 2007. Second annual report on the UK cetacean bycatch monitoring scheme contract report to DEFRA on the work conducted 2005-2006.

 

Prochnow, G. & Kock, K-H., 2000. The protection of harbour porpoise (Phocoena phocoena) in the waters off Sylt and Amrum (German Wadden Sea): A baseline study. Archive of Fishery and Marine Research, 48, 195-207.

 

Read, AJ, Drinker P, & Northridge, S., 2006. Bycatch of marine mammals in US and global fisheries. Conservation Biology, 20, 163-169.