This paper is soon to be published in Biodiversity and Conservation -
Leeney RH, Amies R, Broderick AC, Witt MJ, Loveridge J, Doyle J, Bodley BJ
(2008)
Spatio-temporal analysis of cetacean strandings and bycatch in a UK fisheries
hotspot.
Abstract
Marine vertebrate strandings data can provide insights into the long-term
dynamics of cetacean populations, and the threats they face. We investigate
whether the
spatio-temporal patterns of cetacean strandings around Cornwall, SW Britain,
have
changed in the past century. Analysis of strandings from 1911 to 2006 (n =
2,257) show
that, since the mid-1970s, the relative frequency of strandings of common
dolphins
(Delphinus delphis), harbour porpoises (Phocoena phocoena) and pilot whales
(Globicephala melas) has increased significantly. Seasonal peaks in strandings
frequencies are apparent, between December and March for harbour porpoises and
common dolphins, and between November and January for pilot whales. There were
signifcant positive trends in the number of common dolphin and harbour porpoise
strandings, as a proportion of total strandings, over time. Strandings of
common dolphins, porpoises and all other species occur more frequently on the
south coast of Cornwall. A total of 415 cetaceans were subject to full
veterinary necropsy to determine cause of death, between 1990 and 2006, and 253
(61%) of these individuals were determined to have died due to bycatch in
fishing gear. Analyses of industrialised fishing pressure in UK waters show the
seas around Cornwall to be one of the most heavily fished areas of the UK. We
suggest a number of factors that could
be responsible for the recent increases in cetacean strandings in southwest UK
waters in recent years, including survey effort, as well as abundance and range
shifts that are potentially linked with climate change. Although detectable
levels of bycatch rate have not increased over time, fisheries interactions are
in significant part responsible for mortality patterns and are worthy of more
detailed investigation.
Pdfs are available from Ruth Leeney ([EMAIL PROTECTED]).
Ruth H. Leeney
Namibian Dolphin Project
Walvis Bay, Namibia
T: (+264)-81-386-3886
E: [EMAIL PROTECTED]
W: www.namibiandolphinproject.blogspot.com
W: www.westafricacetaceans.blogspot.com
Skype: ruth.leeney
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