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.

Climate change can alter marine ecosystems through changes in ocean temperature, acidification, circulation, and productivity. Over the last decade, the United States northeast continental shelf (U.S. NES) has warmed faster than any other marine ecosystem in the country and is among the fastest warming regions of the global ocean. Many living marine resources in the U.S. NES ranging from recreational and commercial fish stocks to protected species have shifted their distribution in response to ocean warming. The National Oceanic and Atmospheric Administration’s National Marine Fisheries Service (NOAA Fisheries) is responsible for the assessment, protection, and sustainable use of the nation’s living marine resources. In the U.S. NES, NOAA Fisheries has made substantial progress on climate research related to fish, fisheries, and protected species. However, more research is needed to help inform tactical management decisions with the goal of climate-ready living marine resource management. This is a major challenge because the observed physical and biological changes are unprecedented, and the majority of marine species assessments and management decisions do not utilize environmental data. Here we review the research accomplishments and key needs for NOAA Fisheries in the U.S. NES in the context of climate change and living marine resource management. Key research needs and products are: 1) Infrastructure with continued and enhanced ocean surveys that includes cooperative research with the fishing industry and other NOAA line offices and partners; 2) Tracking and projecting change, and understanding mechanisms including state of the ecosystem reporting, improved regional ocean and ecosystem hindcasts, forecasts, and projections, and continued process-based laboratory and field studies, 3) climate-informed management, including stock assessments that account for climate where possible, translation of changing species distributions into spatial management, climate vulnerability assessment and scenario planning, ecosystem-based management, management strategy evaluations, and increased multidisciplinary science that includes economic and social indicators.

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.

Managing human impacts on marine mammal populations depends on understanding their distributions in space and time. Knowledge of these distributions is becoming increasingly important due to offshore energy development and climate-induced shifts in oceanic habitat. Most models assessing pelagic marine mammal abundance and distribution primarily use ocean surface or ocean floor variables as proxies for water column habitat. Here, we used a ship-based marine mammal sighting survey to test the utility of echosounder-based predictive variables for modeling marine mammal distribution and abundance. We assessed the distribution of 7 marine mammal taxa and 3 feeding guilds along the shelf break off the northeast USA relative to prey structure derived from acoustic data. We classified prey into 4 categories: (1) fish with swimbladders; (2) small resonant bubbles as phytoplankton, fish larvae, and gelatinous zooplankton; (3) fluid-like scatterers such as krill and copepods; and (4) fish with no swimbladder. We quantified the spatial structure of prey by calculating backscattering strength, location, dispersion, occupied areas, evenness, and aggregation. Spatial resolution along the survey track line was set to bins 1000 m in distance and either 50 or 200 m in depth. We then built generalized additive models (GAMs) using these acoustically derived variables to explain marine mammal distribution. The resulting GAMs explained between 9 and 38% of deviance, with model fit often reflecting aspects of foraging depth and prey preference. This approach could contribute to improved management through more accurate species distribution models that employ direct measurements of prey.

Harbour porpoise (Phocoena phocoena) bycatch in the US Northeast gillnet fishery is managed under the Harbour Porpoise Take Reduction Plan (HPTRP), which was implemented on 1 January 1999. The HPTRP divides this fishery into management areas that are either completely closed to all gillnets or closed only to gillnets that do not use pingers. Questions about pingers that have arisen include: (1) would pingers be as effective in an operational fishery as in controlled scientific experiments; (2) would the fishery comply with these regulations; and (3) would harbour porpoises habituate to pingers? To investigate these questions, data from over 25,000 gillnet hauls observed by the Northeast Fisheries Observer Program after the implementation of the HPTRP, 1999-2007, were examined. In a 1994 controlled scientific experiment conducted in part of this fishery that used 15cm mesh gillnets, the bycatch rate in pingered nets was 92% less than that in nets without pingers. In contrast, in the operational fishery, the bycatch reduction in pingered nets was 50-70%, depending on the time, area and mesh size. In particular, there was no observed bycatch in pingered nets that used the same mesh size as used in the experiment. Thus, it seem that the apparent decrease in pinger effectiveness in the operational fishery was partially due to the type of gillnet used and lack of compliance. Pinger usage started out high in 1999 (the first year required), dropped substantially during 2003-05 and perhaps due to outreach activities increased beginning in 2006. During years of high pinger usage, 87% of the tested pingers were functional, while only 36% of the tested pingers were functional during years of low pinger usage. In general, as expected, observed bycatch rates in hauls without pingers were greater than bycatch rates in hauls with the required number of pingers. Unexpectedly, bycatch rates of observed hauls with an incomplete set of pingers were higher that in observed hauls without pingers. Confounding factors that could partially explain this apparently contrary result are discussed. There was no evidence for temporal trends in the bycatch rates, suggesting that harbour porpoises had not habituated to the pingers. In conclusion, in the US Northeast gillnet fishery, harbour porpoises do not appear to have habituated to pingers, and pingers appear to have reduced the bycatch rate, particularly when the required number of pingers were used and in nets using mesh sizes of 15cm or less.

Climate change and climate variability are affecting marine mammal species and these impacts are projected to continue in the coming decades. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species using currently available information. We conducted a trait-based climate vulnerability assessment using expert elicitation for 108 marine mammal stocks and stock groups in the western North Atlantic, Gulf of Mexico, and Caribbean Sea. Our approach combined the exposure (projected change in environmental conditions) and sensitivity (ability to tolerate and adapt to changing conditions) of marine mammal stocks to estimate vulnerability to climate change, and categorize stocks with a vulnerability index. The climate vulnerability score was very high for 44% (n = 47) of these stocks, high for 29% (n = 31), moderate for 20% (n = 22), and low for 7% (n = 8). The majority of stocks (n = 78; 72%) scored very high exposure, whereas 24% (n = 26) scored high, and 4% (n = 4) scored moderate. The sensitivity score was very high for 33% (n = 36) of these stocks, high for 18% (n = 19), moderate for 34% (n = 37), and low for 15% (n = 16). Vulnerability results were summarized for stocks in five taxonomic groups: pinnipeds (n = 4; 25% high, 75% moderate), mysticetes (n = 7; 29% very high, 57% high, 14% moderate), ziphiids (n = 8; 13% very high, 50% high, 38% moderate), delphinids (n = 84; 52% very high, 23% high, 15% moderate, 10% low), and other odontocetes (n = 5; 60% high, 40% moderate). Factors including temperature, ocean pH, and dissolved oxygen were the primary drivers of high climate exposure, with effects mediated through prey and habitat parameters. We quantified sources of uncertainty by bootstrapping vulnerability scores, conducting leave-one-out analyses of individual attributes and individual scorers, and through scoring data quality for each attribute. These results provide information for researchers, managers, and the public on marine mammal responses to climate change to enhance the development of more effective marine mammal management, restoration, and conservation activities that address current and future environmental variation and biological responses due to climate change.

Little is known about the diet of harbor porpoises (Phocoena phocoena) in southern New England where bycatch was a highly contentious issue since the late 1990s until recently. To fill this data gap, stomach contents were examined from 46 harbor porpoises taken as bycatch over 24 years (1994-2017) between January and May. Prey species were identified to the lowest possible taxon through hard part analysis, primarily of otoliths and squid beaks. Size and species of harbor porpoise prey overlapped little with those of gillnet catch. Average prey size was larger for adult harbor porpoises (=140 cm total length), females, and those taken during the first half of our study (1994-2006) than for smaller porpoises, males, and those caught during the second half (2007-2017). Average total biomass consumed per stomach was 2.3 kg, an estimate that represents approximately 12-24 h of feeding. Clupeids, true hakes (Urophycis spp.), squids (Decapodiformes), and silver hake (Merluccius bilinearis) constituted 85.5% of all estimated biomass. Cusk-eels (Ophidiidae) and small flatfish species (Pleuronectiformes) were frequently consumed (found in 29.8% and 27.7% of all stomach samples), but each taxon made up less than 1% of estimated biomass because of their small size. These results could help advance ecosystem-based management by better defining the diet of harbor porpoises in the context of potential climate changes.

The incidental capture, or bycatch, of loggerhead sea turtles Caretta caretta in commercial fishing gear is considered a significant threat to their recovery. Bycatch analyses that use fishery-dependent data only reflect the spatial and temporal co-occurrence of turtles and fishing effort and therefore do not directly reveal conditions associated with turtle distributions. Fishery-independent and -dependent data can be used together to identify environmental conditions associated with turtle presence and the subsequent risk of a bycatch encounter if fishing effort is present. We developed generalized additive models (GAMs) to describe fishery-independent encounter rates of loggerheads observed in aerial and resource surveys in the US mid-Atlantic region as a function of environmental variables. We then fit a fishery-independent GAM to fishery-dependent data collected from commercial gillnet, bottom trawl, and scallop dredge fisheries in the mid-Atlantic region, and tested the model on new fishery-dependent data to assess how well the model predicted bycatch events. The preferred model describes fishery-independent encounter rates as a function of latitude, sea-surface temperature, depth, and salinity. When this model was fit to fishery-dependent data and tested on new data, it predicted 85% of the observed bycatch events when grouped by latitude and season, although it underestimated bycatch events in southern latitudes in winter. We identify times and areas of elevated bycatch risk on which to focus future conservation efforts and observer coverage.

In 1999 the US National Marine Fisheries Service (NMFS) implemented regulations to limit harbor porpoise Phocoena phocoena incidental bycatch in US waters of the northwestern Atlantic. This effort was called the Harbor Porpoise Take Reduction Plan (HPTRP) and included a mixture of time-area closures, pinger and other gear modification requirements, a pinger training program, and outreach and education efforts. This paper focuses on the plan from January 1999 to May 2010 and examines trends in bycatch patterns, compliance with the plan, enforcement of the plan requirements, and changes in the primary fisheries involved in harbor porpoise bycatch. Over the course of the plan harbor porpoise bycatch dropped in the first few years, increased to unacceptable levels during the middle years, and moderated in the later years of the plan. Changes in fishing effort and distribution of key fisheries played a large role in decreasing the bycatch in much of the Mid-Atlantic and also in increasing bycatch in Southern New England and off the coast of New Jersey. The pattern in compliance levels had an inverse relationship with bycatch levels, with better compliance and lower bycatch in early and late years, though compliance was generally poor even when at its best. Enforcement of HPTRP regulations was not well documented, but, from available compliance data, it appears that what enforcement did occur was not sufficient to improve compliance. Given poor compliance with pinger requirements, these requirements have not resulted in the expected reduction in bycatch.

This series is a secondary scientific series designed to assure the long-term documentation and to enable the timely transmission of research results by Center and/or non-Center researchers, where such results bear upon the research mission of the Center (see the outside back cover for the mission statement). These documents receive internal scientific review, and most receive copy editing. The National Marine Fisheries Service does not endorse any proprietary material, process, or product mentioned in these documents. All documents issued in this series since April 2001, and several documents issued prior to that date, have been copublished in both paper and electronic versions. To access the electronic version of a document in this series, go to http://www.nefsc.noaa.gov/nefsc/publications/. The electronic version is available in PDF format to permit printing of a paper copy directly from the Internet. If you do not have Internet access, or if a desired document is one of the pre-April Editorial Treatment: To distribute this report quickly, it has not undergone the normal technical and copy editing by the Northeast Fisheries Science Center's (NEFSC's) Editorial Office as have most other issues in the NOAA Technical Memorandum NMFS-NE series. Other than the four covers and first two preliminary pages, all writing and editing have been performed by the authors listed within. ABSTRACT This report provides incidental take estimates for five marine mammal species observed taken in the 2009 New England sink gillnet (NESG) and Mid-Atlantic gillnet (MAG) fisheries and documents the methodology used to produce the estimates. The estimated incidental takes in the 2009 NSEG fishery were 43 (CV = 77%) common dolphins (Delphinis delphis), 591 (CV = 23%) harbor porpoises (Phocoena phocoena), 1063 (CV = 26%) gray seals (Halichoerus grypus), 516 (CV = 28%) harbor seals (Phoca vitulina), and 415 (CV = 27%) harp seals (Phoca groenlandica). For the MAG fishery, the estimated 2009 incidental takes were 201 (CV = 55%) harbor porpoises, 70 (CV = 69%) harp seals, and 47 (CV = 68%) harbor seals.

Table 3-7: Number of vessels using sink or anchored gillnet gear to land seafood in a given port group..

We developed an estuarine index of biotic integrity to assess habitat quality in Narragansett Bay, Rhode Island. Fish were collected at 18 fixed stations with a 61-m X 3.05-m beach seine once per month in July and August from 1988 to 1999. Stations were designated high or low quality depending on the total nitrogen concentration, number of low dissolved oxygen events, extent of human disturbance, abundance of macroalgae, and presence or absence of eelgrass Zostera marina. We used stepwise discriminant analysis on 13 candidate metrics based on fish community data to determine those most important in distinguishing between high and low habitat categories. We then used discriminant analysis and canonical discriminant analysis with the resulting significant metrics. The six metrics that were able to discriminate between sites were the number of estuarine spawner species, proportion of killifish, number of individuals, proportion of flounder, Shannon's diversity index, and proportion of benthic-associated species. Discriminant analysis with these metrics distinguished among sites with an overall error rate of 22%. Surprisingly, when an index was calculated from the metrics, sites designated as low quality based on environmental data had the highest scores whereas high-quality sites had low scores. Degraded sites in the upper estuary may have scored high due to the availability of shallow-water refuge from predation, abundant food, and warmer water with less current. Our results indicate that upper estuaries are important to juvenile fish and are worth protecting despite apparent human impacts. Further, an index of biotic integrity may not be useful in estuaries because of their characteristically harsh environmental conditions, which result in fish communities that are dominated by tolerant species that are habitat and feeding generalists.

........................................................................................................................................................