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Understanding the impact of marine mammal bycatch - ME6007

Marine mammal populations are well known to be impacted by accidental entrapment in fishing gear through much of the world (Reeves et al 2013), and within the UK as elsewhere accidental capture in fisheries is the primary conservation issue for this species group overall. The UK has international obligations to monitor and where necessary to mitigate bycatch, stemming from agreements under the Bonn Convention on Highly
Migratory Species and through the International Whaling Commission. Under the Aichi targets of the Convention on Biological Diversity, Target 6 under Strategic Goal B is to ensure that "fisheries have no significant adverse impacts on threatened species and vulnerable ecosystems and the impacts of fisheries on stocks, species and ecosystems are within safe ecological limits". There are also binding obligations under the EU Habitats Directive to monitor bycatch and address conservation concerns, while the Marine Strategy Framework Directive requires member states to ensure good environmental status (GES), and the UK sees continued bycatch monitoring and mitigation as key to ensuring GES is maintained (Marine Strategy Part Three: UK Programme of Measures December 2015). The UK has been in the forefront of international efforts to ensure fishery impacts on marine mammals are understood and addressed.

Estimates of cetacean bycatch in UK fisheries have been produced annually since 2006 under Council Regulation 812/2004, while the bycatch mitigation measures stipulated in that Regulation have also been implemented and monitored over this same period. A concern with the existing Regulation is that it is directed primarily at vessels of 12m or more in length, whereas most of the vessels using static nets are under 12m in length. One way to address this deficiency could be to ensure all vessels use acoustic deterrent devices to reduce the bycatch of porpoises at least. However, there may well be detrimental consequences to such an approach, if bycatch rates of other species (bottlenose dolphins or seals) are increased by the use of acoustic deterrents, or if porpoises are excluded from important foraging or calving grounds through widespread use of pingers. A more detailed analysis is required to characterise the conservation implications of bycatch by fishery sector and by region in a more detailed manner than has been achieved so far. Such analysis should also highlight areas and fisheries where bycatch rates are highest, such that targeted bycatch reduction assessed as a possible alternative to blanket pinger deployment over the whole of the netting fleet.
1. Sea Mammals Research Unit (SMRU) will use their existing database on observations of marine mammal bycatch in UK fisheries to generate bycatch estimates of seals, dolphins and porpoises by static net type (target species or gear characteristics - both will be assessed) and by region. To do this SMRU will also need to analyse UK fleet fishing effort data from the iFish database extraction compiled annually by the MMO to estimate the amount of static net fishing effort by static net type and region.
2. SMRU will explore and describe bycatch rates by the under 12 m sector and the over 12 m sector, and look for areas of high bycatch by coastal region and by depth zone or distance from shore. SMRU will identify fishery types, regions and seasons with the highest bycatch rates and provide stratified estimates of annual bycatch accordingly, including risk based maps.
3. SMRU will review and compile available abundance estimates and information from other EU member states whose fishing activities may impact populations of marine mammals in the English Channel and Celtic Sea and provide an assessment of the overall likely threat to marine mammal populations.
4. SMRU will begin to explore the relationship between bycatch rate and porpoise density by deploying echolocation click recorders and analysing their data (including development or improvement of new tools for analysis). Some preliminary results indicating click detection rates by gear type and possibly by region may be expected, though a longer period of data collection will be required to develop this as a tool for monitoring and predicting cetacean encounter and bycatch rates.
Time-Scale and Cost
From: 2017

To: 2017

Cost: £100,000
Contractor / Funded Organisations
Sea Mammal Research Unit
Marine Mammels