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

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.

Drivers of spatiotemporal variability in bycatch of a top marine predator: First evidence for the role of water turbidity in protected species bycatch

“…While this is a valid assumption for the purposes of this analysis (e.g. Jones et al, ), in reality, the distribution of seals is more likely to be habitat‐mediated, or follow consistent corridors between foraging grounds or distant colonies (Cronin, Gerritsen, & Reid, , ; Jessopp, Cronin, & Hart, ; Jones et al, .…”

Addressing Marine and Coastal Governance Conflicts at the Interface of Multiple Sectors and Jurisdictions

“…Total loss of landings could be over 50% in both the pollack and hake fisheries, with an estimated value of €1.7 m, when the fish entirely removed from nets were taken into account. This has led to a clear conflict in interests between the fishing industry and conservation sector, particularly environmental NGOs (Cronin et al, 2016). Responsibility for seal conservation and seal/fishery interactions also involve two different government departments.…”

Bio-telemetry as an Essential Tool in Movement Ecology and Marine Conservation

“…Additionally, food resources may change at the local scale due to other anthropogenic influences. Local depletion and competition with fisheries can be regarded as general examples of the latter (Lidgard et al 2014;Cronin et al 2016). A topical issue is the future European Union ban on fisheries discards, currently providing a major resource for a wide range of seabird species (Garthe et al 1996;Furness 2003;Votier et al 2010Votier et al , 2013Bicknell et al 2013;Krüger et al 2017).…”

“…Most bio-telemetry devices for pinnipeds are non-invasive and commonly glued to the fur by using epoxy resin (Fedak et al 1983;Lowther et al 2013;Nachtsheim et al 2017), or more recently, superglue (Cronin et al 2016). The devices are either actively recovered or remain on the animal for up to one year until they fall off during the next annual molt.…”