Cooperative hunting, in its numerous forms, has implications for animal cognition and social evolution. We used multi-sensor acoustic/video recording tags attached to free-swimming humpback whales (Megaptera novaeangliae) to provide the species’ first documentation of cooperative, coordinated benthic hunting and evidence supporting collaboration, the most cognitively complex level of hunting. Collaborative hunting, consisting of the tagged whale and 1–3 co-hunters, comprised 79
As offshore wind development continues across the globe, accurate spatial data are required to characterize fishing activity, inform wind farm siting decisions, and estimate economic exposure. We assess the influence of fishing behavior and fleet definition within a multispecies fishery on coarse (logbook-based) footprint biases using a precise (GPS-based) approach. We constructed precise footprints for 838 trips that caught summer flounder (Paralichthys dentatus) trips and 1439 trips that caught any species in the Summer Flounder, Scup (Stenotomus chrysops), and Black Sea Bass (Centropristis striata) Fishery Management Plan from 2016 to 2021. Using the precise footprints as a ground truth, we compared the intersections and estimated economic exposure between coarse footprints (restricted to the 90th, 75th, 50th, and 25th percentiles) for 37 wind farms in the northeast USA. Unrestricted coarse footprints (90th percentile) consistently identified all “true” intersections with wind farms while also overestimating economic exposure. For the multispecies fisheries, restricting footprints between 25th and 50th percentile yielded the most accurate estimates of economic exposure. This contrasts previous work that found the 25th percentile was most accurate for the targeted longfin squid (Doryteuthis pealeii) fishery, highlighting the importance of fleet definition in this process. Replicating this approach for other fisheries will allow development of a tool to accurately estimate economic exposure by restricting coarse footprints in the absence of fine-scale data.
In recent years, humpback whales (Megaptera novaeangliae) have been observed in the waters of the US mid-Atlantic states (USMA; New Jersey to North Carolina), notably in winter. The level of the mortality in this area (52 recorded deaths from 1990-2000), makes it important to understand the nature and population identity of this aggregation. Of the approximately 100 humpback whales documented in this study, photographs of 41 (live or dead) were of sufficient quality to be compared to catalogues from the Gulf of Maine (GOM, the closest feeding ground) and elsewhere in the North Atlantic. Of 22 live whales, 10 (45.5%) matched to the GOM, 5 (22.7%) to Newfoundland and 1 (4.5%) to the Gulf of St Lawrence (GSL). Of 19 dead whales, 6 (31.6%) were known GOM whales. Although the population composition of the USMA is dominated by GOM whales, lack of recent photographic effort in Newfoundland makes it likely that the observed match rates under represent the true presence of Canadian whales in the region. Length data from 48 stranded whales (18 females, 22 males and 8 of unknown sex) suggest that 39 (81.2%) were first-year animals, 7 (14.6%) were immature and 2 (4.2%) were adults. However, sighting histories of five of the dead whales indicate that some were small for their age and histories of live whales further indicate that the population contains a greater percentage of mature animals than is suggested by the stranded sample. The authors suggest that the study area primarily represents a supplemental winter feeding ground that is used by humpbacks for more than one purpose. From a management perspective, although the only successful matches of mortalities to date have been to the GOM, the observed mixing of live whales from different summer stocks might suggest that the high numbers of mortalities occurring there may not be impacting this single stock alone. Although further data are required before conclusions can be drawn, the mortality rate may be significant for the GOM population and this warrants further investigation.
Humpback whales ( Megaptera novaeangliae ) exhibit maternally driven fidelity to feeding grounds, and yet occasionally occupy new areas. Humpback whale sightings and mortalities in the New York Bight apex (NYBA) have been increasing over the last decade, providing an opportunity to study this phenomenon in an urban habitat. Whales in this area overlap with human activities, including busy shipping traffic leading into the Port of New York and New Jersey. The site fidelity, population composition and demographics of individual whales were analysed to better inform management in this high-risk area. Whale watching and other opportunistic data collections were used to identify 101 individual humpback whales in the NYBA from spring through autumn, 2012–2018. Although mean occurrence was low (2.5 days), mean occupancy was 37.6 days, and 31.3% of whales returned from one year to the next. Individuals compared with other regional and ocean-basin-wide photo-identification catalogues (N = 52) were primarily resighted at other sites along the US East Coast, including the Gulf of Maine feeding ground. Sightings of mother-calf pairs were rare in the NYBA, suggesting that maternally directed fidelity may not be responsible for the presence of young whales in this area. Other factors including shifts in prey species distribution or changes in population structure more broadly should be investigated.
Toothed whales (Odontocetes) are highly mobile animals that play key trophic roles in ecosystems and whose habitats often overlap with areas of human activity. To mitigate detrimental effects of this overlap, it is critical to understand their habitat use patterns. The Stellwagen Bank National Marine Sanctuary in the western Gulf of Maine is a hypothesized foraging area for toothed whale species and an area of high human use, but odontocete habitat use there is poorly understood. While a large whale watch community provides a robust, long-term, opportunistic sighting data set, those data are not standardized. To overcome this limitation, we used point process models to analyze 10 yr of opportunistic sighting data. We identified spatial distribution patterns and environmental predictors for the 2 most common odontocete species in the sanctuary, Atlantic white-sided dolphins Lagenorhynchus acutus and harbor porpoise Phocoena phocoena. Habitat use differed among months, and depth, slope, substrate, and salinity were the most important and consistent predictors for both species. Models identified both persistent and shifting hotspots within the sanctuary. While presence was strongly associated with several covariates, environmental predictors did not fully explain shifting hotspots. This work highlights the importance of long-term opportunistic data collection and provides new knowledge on habitat use to inform assessment and management of potential human impacts on odontocetes in a federal marine protected area.
