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Marine mammals are affected throughout their range by fisheries bycatch (Read et ah, 2006; Lewison et ah, 2014; Burgess et ah, 2018; Gray and Kennedy, 2018) and increasingly by climate [...]

Managing fishing operations' threat to marine mammal populations hinges on accurate bycatch estimates, often derived from fishery observer or monitoring programmes. Much global marine mammal bycatch occurs in gillnets, and observer protocols that do not include watching the haulback of gillnets may miss animals that drop out of the net. We investigated whether trips using a fish-focused observer protocol (no requirement to watch the haulback) in US northwestern Atlantic gillnet fisheries from 1994 to 2019 had different observed bycatch rates from trips under a mammal-focused observer protocol (watching the haulbacks) for grey seals (Halichoerus grypus atlantica), harbour seals (Phoca vitulina vitulina), and harbour porpoise (Phocoena phocoena phocoena). We found that observer protocol was likely to affect observed drop-out and bycatch rates. Under the fish-focused protocol, the ratio of animals removed from the net to those that fell from the net was generally higher than under the mammal-focused protocol, suggesting fish-focused observers missed bycatch that fell. Bycatch rates of animals removed from the net by fishers differed significantly between observer protocols for seals, but not for harbour porpoise, perhaps because of differences in entanglement and manner of decomposition. We estimate bycatch was underreported by 3–25% because of unobserved drop-outs on fish-focused observer protocols. [ABSTRACT FROM AUTHOR]

Copepod size and energy content are influenced by regional and seasonal variation in temperature and food conditions, with implications for planktivorous consumers such as the endangered North Atlantic right whale (Eubalaena glacialis). Historical data (1990–2020) on Calanus finmarchicus stage CV copepodite prosome length and oil sac metrics were analyzed to determine the extent of variation in individual body size and estimated lipid and energy content in five regions of the Northwest Atlantic continental shelves [Gulf of Maine (GoM), Scotian Shelf (SS), Gulf of St. Lawrence (GSL), St. Lawrence Estuary (SLE) and Newfoundland Shelf]. Large-scale spatial patterns in size and lipid content were related to latitude, indicating that C. finmarchicus CV in the GSL and SLE were historically larger in body size, and had significantly higher lipid content compared with those in the GoM and the SS. The observed patterns of C. finmarchicus CV size and lipid storage capacity suggest that regional variation in whale prey energy content can play a role in the suitability of current and future whale foraging habitats in the Northwest Atlantic, with the larger lipid-rich individuals in the GSL providing a high-quality diet compared with those in southern areas. [ABSTRACT FROM AUTHOR]

The article investigates the data collected by the Northeast Fisheries Observer Program (NEFOP) documenting patterns in harbour porpoise bycatch rates, the compliance levels of pinger regulations and possible habituation indications in the U.S. Northeast gillnet fishery. It notes that the Harbour Porpoise Take Reduction Plan (HPTRP) separates the fishery into management areas that are either completely closed to all gillnets or closed to those that do not use pingers. It was found out that there was no observed bycatch in pingered nets using the same mesh size used in the experiment. It was found out that 87% of the tested pingers were functional during high pinger usage, while 36% were functional during low pinger usage.