Spatial Overlap of Grey Seals and Fisheries in Irish Waters, Some New Insights Using Telemetry Technology and VMS

PLoS One. 2016 Sep 28;11(9):e0160564. doi: 10.1371/journal.pone.0160564. eCollection 2016.

Abstract

Seals and humans often target the same food resource, leading to competition. This is of mounting concern with fish stocks in global decline. Grey seals were tracked from southeast Ireland, an area of mixed demersal and pelagic fisheries, and overlap with fisheries on the Celtic Shelf and Irish Sea was assessed. Overall, there was low overlap between the tagged seals and fisheries. However, when we separate active (e.g. trawls) and passive gear (e.g. nets, lines) fisheries, a different picture emerged. Overlap with active fisheries was no different from that expected under a random distribution, but overlap with passive fisheries was significantly higher. This suggests that grey seals may be targeting the same areas as passive fisheries and/or specifically targeting passive gear. There was variation in foraging areas between individual seals suggesting habitat partitioning to reduce intra-specific competition or potential individual specialisation in foraging behaviour. Our findings support other recent assertions that seal/fisheries interactions in Irish waters are an issue in inshore passive fisheries, most likely at the operational and individual level. This suggests that seal population management measures would be unjustifiable, and mitigation is best focused on minimizing interactions at nets.

Grants and funding

MC was supported by a Beaufort Marine Research Award (BEAU-EAFM-06), carried out under the Sea Change Strategy and the Strategy for Science Technology and Innovation (2006–2013), with the support of the Marine Institute, funded under the Marine Research Sub-Programme of the National Development Plan 2007–2013. Fieldwork and equipment costs were supported by a grant from the National Geographic Society Global Exploration Fund (GEFNE9-11) and from Inland Fisheries Ireland under the Salmon Conservation Fund (CRA/2011/183). MJ was supported by Science Foundation Ireland (SFI) under Marine Renewable Energy Ireland (MaREI) centre funding (SFI/12/RC/2302). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.