Capture of sea turtles in longline fisheries has been implicated in population declines of loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles. Since 2004, United States (U.S.) longline vessels targeting swordfish and tunas in the Pacific and regions in the Atlantic Ocean have operated under extensive fisheries regulations to reduce the capture and mortality of endangered and threatened sea turtles. We analyzed 20 + years of longline observer data from both ocean basins during periods before and after the regulations to assess the effectiveness of the regulations. Using generalized additive mixed models (GAMMs), we investigated relationships between the probability of expected turtle interactions and operational components such as fishing location, hook type, bait type, sea surface temperature, and use of light sticks. GAMMs identified a two to three-fold lower probability of expected capture of loggerhead and leatherback turtle bycatch in the Atlantic and Pacific when circle hooks are used (vs. J hook). Use of fish bait (vs. squid) was also found to significantly reduce the capture probability of loggerheads in both ocean basins, and for leatherbacks in the Atlantic only. Capture probabilities are lowest when using a combination of circle hook and fish bait. Influences of light sticks, hook depth, geographic location, and sea surface temperature are discussed specific to species and regions. Results confirmed that in two U.S.-managed longline fisheries, rates of sea turtle bycatch significantly declined after the regulations. In the Atlantic (all regions), rates declined by 40 and 61% for leatherback and loggerhead turtles, respectively, after the regulations. Within the NED area alone, where additional restrictions include a large circle hook (18/0) and limited use of squid bait, rates declined by 64 and 55% for leatherback and loggerhead turtles, respectively. Gains were even more pronounced for the Pacific shallow set fishery, where mean bycatch rates declined by 84 and 95%, for leatherback and loggerhead turtles, respectively, for the post-regulation period. Similar management approaches could be used within regional fisheries management organizations to reduce capture of sea turtles and to promote sustainable fisheries on a global scale.

In order to adequately monitor biodiversity trends through time and their responses to natural or anthropogenic impacts, researchers require long time series that are often unavailable. This general lack of datasets that are several decades or longer makes establishing a background or baseline of diversity metrics difficult - especially when attempting to understand species composition changes against a backdrop of climate and ecological variability. Here, we present an analysis of a community of juvenile nearshore fishes based on nearly 8 decades of highly standardized Norwegian survey records. Using multivariate statistical techniques, we: (i) characterize the change in taxonomic community composition through time, (ii) determine whether there has been an increase in warm-water affinity species relative to their cold water affinity counterparts, and (iii) characterize the temporal change in the species' functional trait assemblage. Our results strongly indicate a shift toward a novel fish assemblage between the late 1990s and 2000s. The context of changes within the most recent two decades is in stark contrast to those during the 1960s and 1970s, but similar to those during the previous warm period during the 1930s and 1940s. This novel assemblage is tightly linked to the warming temperatures in the region portrayed by the increased presence of warm-water species and a higher incidence of pelagic, planktivorous species. The results indicate a clear influence of ocean temperature on the region's juvenile fish community that points to climate-mediated effects on the species assemblages of an important fish nursery area.

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Marine animals, such as turtles, seabirds and pelagic fishes, are observed to travel and congregate around eddies in the open ocean. Mesoscale eddies, large swirling ocean vortices with radius scales of approximately 50–100 km, provide environmental variability that can structure these populations. In this study, we investigate the use of mesoscale eddies by 24 individual juvenile loggerhead sea turtles (Caretta caretta) in the Brazil-Malvinas Confluence region. The influence of eddies on turtles is assessed by collocating the turtle trajectories to the tracks of mesoscale eddies identified in maps of sea level anomaly. Juvenile loggerhead sea turtles are significantly more likely to be located in the interiors of anticyclones in this region. The distribution of surface drifters in eddy interiors reveals no significant association with the interiors of cyclones or anticyclones, suggesting higher prevalence of turtles in anticyclones is a result of their behavior. In the southern portion of the Brazil-Malvinas Confluence region, turtle swimming speed is significantly slower in the interiors of anticyclones, when compared to the periphery, suggesting that these turtles are possibly feeding on prey items associated with anomalously low near-surface chlorophyll concentrations observed in those features.

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