Estimates of humpback and minke whale entanglements in the Scottish static pot (creel) fishery

Abstract

Entanglement in static fishing gear (pots, or creels as they are called in Scottish fisheries) is a major cause of anthropogenic mortality and morbidity in large whales globally; in northeastern Atlantic waters around the coast of Scotland, entanglement is a particular welfare and conservation concern for minke whales Balaenoptera acutorostrata and humpback whales Megaptera novaeangliae. Reports from strandings, live disentanglements and interviews with Scottish inshore creel fishers were gathered to estimate entanglement rates. Considerably more whale entanglements occur in the Scottish creel fishery than previously thought based on strandings alone, with estimates of 6 humpback whales and 30 minke whales becoming entangled each year. Where entanglement type was reported, 83% of minke and 50% of humpback whales were caught in groundlines between creels. There was a positive correlation between the average amount of gear set by a vessel and the number of minke whale entanglements. For the west coast of Scotland, the estimated annual fatal entanglement rate of minke whales is 2.3% of a recent abundance estimate, suggesting a risk of localised depletion. There are very low densities of humpback whales in Scottish waters, but opportunistic observations suggest numbers are increasing. The estimated number of annual humpback whale entanglements also shows an increasing trend. There are few entanglement estimates for static pot fisheries globally; this study provides an indication of how such data might be derived. Scottish creel fishers have shown a willingness to engage in entanglement mitigation, with suggestions such as the introduction of sinking groundline to the sector, and these options should be urgently pursued.