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Studying how host characteristics and ecology affect the mating systems of symbiotic crustaceans offers an opportunity to understand how ecological factors contribute to the evolution of different animal mating systems. In theory, symbiotic crustaceans should display social monogamy with long-term heterosexual pairing when hosts are relatively small in body size and structurally simple, and when hosts have relatively low abundance in habitats where the risk of mortality for symbionts (e.g., predation) away from hosts is high. We test this prediction in the mating system of the flotsam crab ( Planes major ) and its facultative association with loggerhead sea turtles ( Caretta caretta ). First, we found that the overall population and sex distributions were non-random and crabs inhabited host turtles as heterosexual pairs more frequently than expected by chance, which supports the hypothesis that P . major is socially monogamous on C . caretta . Second, we found that male crabs pair with females regardless of their reproductive state, male–female pairs do not display size-assortative pairing, crab body size and host turtle body size are not correlated, and crabs display reverse sexual dimorphism in body size and conventional sexual dimorphism in weaponry. These results do not support the hypothesis that social monogamy in P . major is always long term. Instead, our results suggest that the duration of social monogamy in P . major is likely variable and may involve some degree of host switching and intra-sexual (mostly male–male) competition. Our results were only partially consistent with theoretical considerations for how host characteristics and ecology affect the mating systems of symbiotic crustaceans, and future studies should focus on quantifying the degree and direction of host switching to better understand the factors that affect the duration of monogamous pairing when P . major associates with C . caretta . [ABSTRACT FROM AUTHOR]

Since 1991, Projeto TAMAR-IBAMA, the Brazilian sea turtle conservation program, has maintained a station in Ubatuba, State of São Paulo, southeastern Brazil, a feeding area for sea turtles where incidental capture in coastal fisheries occurs. We present an overview of the local fishing methods, explain the conservation approach and field methods employed by TAMAR in the region, present biological data collected between 1991 and 1998, and provide an assessment of the conservation status of sea turtles in the Ubatuba region. During the study period, 2,515 captures of sea turtles were recorded, comprising four species: green turtles (Chelonia mydas, 98.4% of total captures, generally juveniles), loggerheads (Caretta caretta), hawksbills (Eretmochelys imbricata), and leatherbacks (Dermochelys coriacea). Most of the data come from turtles incidentally captured in fishing gear, mainly by artisanal methods. The available data suggest that Ubatuba is a developmental habitat for juvenile green turtles. [ABSTRACT FROM AUTHOR]

Sea turtles are globally threatened due to short- and long-term exposure to anthropogenic activities. Many life-history traits make it difficult to study these species in the wild. Stranding events provide invaluable data to infer key aspects of sea turtle ecology, such as regional occurrence, health status, mortality rates, and potential threats. In this study, we investigate spatial and temporal patterns of sea turtle occurrence and mortality in the southwestern Atlantic Ocean based on a systematic, large-scale survey programme covering 1040 km of coastline during 732 d of two consecutive years. From the 12 571 animals recovered, juvenile green turtles were the most common (90.4%), but four other species were also recorded. A significant non-linear effect of time and space in the number of stranding events was observed. The most parsimonious mixed linear model further indicated that stranding events were influenced by individual (sex, size), health (body condition, pathologies, decomposition), and oceanographic factors (chlorophyll-a, sea surface temperature, salinity, wave height). More than simply describing the spatiotemporal occurrence and aspects of sea turtles' life history in an otherwise understudied area, this intensive field study provides evidence for relatively high mortality rates—an essential baseline information for guiding conservation efforts. [ABSTRACT FROM AUTHOR]

Sea turtle populations underwent severe decline in historical times, mainly through harvesting eggs and adults on nesting beaches. With the reduction of this threat in many areas, coupled with other conservation actions, some populations have demonstrated encouraging recovery, although remaining below their previous levels and undergone additional modern threats such as incidental capture in fisheries and pollution. Trends in sea turtle populations have usually been assessed through monitoring of females or nests on nesting beaches. Here we present data from a 22-year monitoring period for a juvenile green sea turtle Chelonia mydas mixed-stock in southeastern Brazil that were incidentally captured in passive non-lethal pound nets. A total of 3639 green turtles were captured in 5323 fishing days.pound −1 with mortality rate of 2%. Captures occurred in all months, but bycatch rates, excluding recapture events, were higher in September and October, probably due to the recruitment of turtles migrating from southern areas, as well as recruits from the oceanic zone. Capture rates increased by 9.2% per year in the period from 1995 to 2016, in line with increasing source populations, particularly the main source contributor at Ascension Island, but also Trindade Island (Brazil) and Aves Island (Venezuela). Mean Curved Carapace Length of green turtles was higher during austral summer/early autumn and decreased markedly in May, probably due to the small-sized individuals that recruited to the study site. We show that the incidental capture of sea turtles in non-lethal fisheries, such as Brazilian pound nets, could also provide data on trends of populations nesting in distant places, and can contribute to the assessment of population status of sea turtles within Regional Management Units throughout the Atlantic Ocean. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The population abundance estimates used in stock assessments or required to establish management measures, depend on the sampling of the entire demographic spectrum of a population resident in a given area. However, for sea turtles, most population estimates are based mainly on nesting beach survey data and only consider a fraction of the population. The Southwest Atlantic Ocean (SWA) is an important foraging and development area for juveniles of the loggerhead sea turtle Caretta caretta where reproductive stocks from various nesting beaches mix. Declines in C. caretta populations have been observed in many parts of the world and bycatch rates of this species in the SWA are among the highest worldwide. This study standardizes the catch rates of loggerheads caught by pelagic longline fisheries in the region, using data collected by observer programs from Brazil and Uruguay. Generalized linear models (GLM) with a delta lognormal approximation were used. The variables used in the model take into account spatial and temporal variations as well as the characteristics of the fleet. In total, 6 272 344 hooks were observed between 1998 and 2007, with minimum effort registered in 2000 (12 010 hooks) and maximum effort in 2005 (1 989 431 hooks). During this period 3778 loggerheads were incidentally captured. The catch rates of loggerheads by the Uruguayan and Brazilian pelagic longline fisheries show oscillations through the years without a clear tendency; however, a low negative trend was observed from 1998 to 2005 with an increase in the last two years (2006 and 2007). The capture per unit of effort (CPUE) values varied between 0.38 to 1.78 ind/1000 hooks in 2005 and 2007, respectively. Distinct zones with differential catch rates were identified, with the higher CPUE values over the continental slope of Uruguay and adjacent waters. The incidental catch rates of this species are influenced, not only by fishing area, but also by year, season, sea surface temperature and gear type. In consequence, these variables and other potential ones should be considered in bycatch estimates by different fisheries because the loggerhead sea turtles are not uniformly distributed. This study intends to contribute not only to the general knowledge of loggerhead sea turtles in the SWA but to a future assessment of their populations at a global scale. [ABSTRACT FROM AUTHOR]

Abstract: The decline of populations of certain seabirds and sea turtles around the world is partly related to their incidental capture in large-scale fisheries. However, the impacts of small-scale fisheries on endangered seabirds and sea turtles, being carried out in many places around the world, have been largely neglected by scientists and governments. We monitored 178 fishing days and described a range of poorly known hook-and-line commercial fisheries carried out by the Itaipava fleet, southeastern Brazil, composed by 497 vessels and deploying hooks from 18°S to 35°S. Seven fisheries were defined: fast trolling for tuna and tuna-like species, slow trolling for Bigeye tuna, handlining, surface longline for Dolphinfish, pelagic longline for Swordfish, bottom dropline, and pole-and-line with live bait. We observed bycatch of 47 seabirds of six species and 45 turtles of four species. Capture rates were higher for the surface longline for Dolphinfish (0.15 birds/1000 hooks and 1.08 turtles/1000 hooks), slow trolling for Bigeye tuna (0.41 birds/day) and handlining targeting Yellowfin tuna (0.61 birds/day). Endangered Spectacled petrel (Procellaria conspicillata), Atlantic Yellow-nosed (Thalassarche chlororhynchos), and Black-browed (T. melanophris) albatrosses were the main seabirds caught. Immature Loggerhead turtles (Caretta caretta) and immature or adult Leatherback turtles (Dermochelys coriacea) were the main sea turtles affected by the surface longline for Dolphinfish. Monitoring the fleet and bycatch levels, development of mitigation measures, establishment of educational programs, government control over the fleet, and enforcement, are urgently required for the hook-and-line fisheries described in the present study. [Copyright &y& Elsevier]

Green sea turtles (Chelonia mydas) switch habitats during their development, moving from pelagic to neritic areas and then commuting between nesting and foraging grounds during adulthood. Due to their predominantly coastal habitats, they are under a range of anthropogenic threats. We monitored turtles incidentally captured in fishing weirs in Ceará state, northeastern Brazil, over a decade and provided an overview of capture rates in the fishery during previous decades. Between 2008 and 2018, 2335 captures were recorded, 76% were only once. Most recaptures (86%) occurred up to six months after the first capture, with a mean growth rate of 6.7 ± 3.6 cm year−1. Capture rates varied between years, with the highest rates during the historical period, peaking in 1962 (0.16 turtles day weir−1). Between 2008 and 2018, the daily capture rate was 0.07 turtles day weir−1. Similar to other areas, the use of turtles as a fishery resource seems to have reduced population sizes in the Atlantic Ocean. On the other hand, the intensive monitoring of local weirs provided an opportunity to mobilize the community regarding their conservation, which in turn could have supported the recovery of turtles from a number of distant colonies. The relatively constant and year-round capture of green sea turtles reflects the presence of individuals from different rookeries and demonstrates the importance of the region as a developmental ground for juveniles from different nesting areas, with high growth rates compared with other feeding areas. Partnership with local fishermen and the long-term monitoring of passive nonlethal fishing weirs are key tools in supporting sea turtle conservation. • Interdecadal overview of sea turtle captures show influence of conservation actions. • Fishermen behavior towards sea turtle meat consumption changed. • Fishing weirs over 5 m depth capture turtles with curved carapace length >50 cm. • Most recaptures occurred within six months, suggesting regional residence. • In the tropical area, green sea turtles had higher growth rates than elsewhere. [ABSTRACT FROM AUTHOR]