Spatiotemporal patterns of overlap between short-finned pilot whales and the U.S. pelagic longline fishery in the Mid-Atlantic Bight: An assessment to inform the management of fisheries bycatch

Predicting fisheries bycatch: A case study and field test for pilot whales in a pelagic longline fishery

“…Predicted high‐risk areas occurred further north and covered a broader area from May through October due to warmer SST values in higher latitudes during these months, reaching a maximum of 45.9% of the area identified using the static approach in August through October. However, it is important to note that particularly in winter months, the static approach examined here likely overestimates the area used by fishers; during winter months, longline fishing effort typically occurs in cooler waters than pilot whale observations, but is less likely to occur in the northernmost extent of the MAB and NEC (Stepanuk et al ).…”

“…Pilot whales depredate both bait and catch from longlines, and bycatch in the pelagic longline fishery is the primary source of human‐caused M/SI for the Northwest Atlantic stock of short‐finned pilot whales (Hayes et al, ). Stepanuk et al () found that seasonal variability in longline effort relative to the 1,000‐m isobath influenced seasonal patterns in pilot whale‐longline overlap, which was strongly and significantly correlated with rates of pilot whale bycatch. However, the role of dynamic oceanography in driving patterns of bycatch requires further attention.…”

“…Lastly, we compared spatial predictions of the model during a period of high BPUE with those from a period of low BPUE when fishing effort covered a similar spatial extent to assess whether model could be used to predict temporal periods of high bycatch, and to shed light on why bycatch was so high during these time periods. Specifically, we compared model predictions for December 2015, when pilot whale BPUE was particularly high (Stepanuk et al, ; 0.32 pilot whales per set), with predictions during the same month in previous years, when pilot whale BPUE occurred at more typical levels (0.077 pilot whales per set during December 2010–2014).…”

When large marine predators feed on fisheries catches: Global patterns of the depredation conflict and directions for coexistence

“…In some regions, the use of satellite tagging increased knowledge on preferred areas of predators, and therefore, on areas where fishers were the most likely to be subject to depredation (e.g. Cronin, Gerritsen, Reid, & Jessopp, 2016;Oksanen, Niemi, Ahola, & Kunnasranta, 2015;Stepanuk, Read, Baird, Webster, & Thorne, 2018;Straley et al, 2014;Thorne, Baird, Webster, Stepanuk, & Read, 2019). Move-on practices, although commonly used by fishers, were shown effective only when vessels travelled distances sufficiently large to reduce the chances of being actively followed by predators (Forney, Kobayashi, Johnston, Marchetti, & Marsik, 2011;Janc et al, 2018;Tixier et al, 2018;Tixier, Vacquie Garcia, Gasco, Duhamel, & Guinet, 2015).…”

“…Studies of spatiotemporal factors have identified peak areas of depredation associated with strong overlaps between natural foraging grounds of predators and fishing operations (González et al, 2015;Nitta & Henderson, 1993;Seminara, Barbosa-Filho, & Pendu, 2019;Stepanuk et al, 2018;Wickens, 1995) and/or distances from haul-out sites for pinnipeds (Cronin, Jessopp, Houle, & Reid, 2014;Hückstädt & Antezana, 2003). Similarly, peak in depredation were associated with seasonal variation in species co-occurrence with fisheries due to their phenology (reproduction or migrations) (Bombau & Szteren, 2017;De María, Barboza, & Szteren, 2014;Janc et al, 2018).…”