Abundance, distribution, and habitat of leatherback turtles (Dermochelys coriacea) off California, 1990−2003

Leatherback turtles (Dermochelys coriacea) are regularly seen off the U.S. West Coast, where they forage on jellyfish (Scyphomedusae) during summer and fall. Aerial line-transect surveys were conducted in neritic waters (<92 m depth) off central and northern California during 1990−2003, providing the first foraging population estimates for Pacific leatherback turtles. Males and females of about 1.1 to 2.1 m length were observed. Estimated abundance was linked to the Northern Oscillation Index and ranged from 12 (coefficient of variation [CV] =0.75) in 1995 to 379 (CV= 0.23) in 1990, averaging 178 (CV= 0.15). Greatest densities were found off central California, where oceanographic retention areas or upwelling shadows created favorable habitat for leatherback turtle prey. Results from independent telemetry studies have linked leatherback turtles off the U.S. West Coast to one of the two largest remaining Pacific breeding populations, at Jamursba Medi, Indonesia. Nearshore waters off California thus represent an important foraging region for the critically endangered Pacific leatherback turtle

Hybridization Between a Green Turtle, Chelonia mydas, and Loggerhead Turtle, Caretta caretta, and the First Record of a Green Turtle in Atlantic Canada

The Green Turtle (Chelonia mydas) principally occupies tropical and subtropical waters, although juveniles are known to occur seasonally in temperate coastal waters. Collaboration with commercial fishers in eastern Canada yielded the most northerly records of this species in the northwest Atlantic. Here we report on the first confirmed record of a Green Turtle in eastern Canada and on the occurrence of a rare Green Turtle&ndash;Loggerhead Turtle (Caretta caretta) hybrid. Hybridization between the Carettini and Chelonini is extraordinary given that these groups have been genetically distinct for 50 million years or more

Kinship genomics approach to study mating systems in a depleted sea turtle rookery

Knowledge of demographic processes and life history strategies is necessary for the conservation and management of endangered sea turtle populations, but it is difficult to ascertain because of the limited accessibility to marine environments that sea turtles use during the different stages of their life cycle. In such cases, molecular genetics and genomic approaches are useful to assess mating systems and operational sex ratios (OSR), which ultimately influence demography. This pilot study used genome-wide single nucleotide polymorphism (SNP) genetic markers for exploring kinship and mating systems in sea turtles where major obstacles prevent a comprehensive assessment in the wild. We sampled 217 young hawksbill turtles (Eretmochelys imbricata) of unknown parentage that had originally been collected locally from seven nests and were being temporarily kept in captivity by Treasure Island Ltd as part of its captive rearing conservation project at Bounty and Treasure Islands, Fiji, in the South Pacific. The raw dataset comprised 13,573 SNPs, of which we retained 639 SNPs for parentage and relatedness analyses. Our findings from seven different pairs of parents suggest a 1:1 male:female OSR and demonstrate that genome-wide SNP genotyping approaches can be used to infer OSR. Knowledge of OSR can help evaluate the magnitude of the impact of warming temperatures and consequent feminisation in sea turtles. Our approach can complement or substitute field observation of breeding males and nesting females when logistical or budgetary constraints prevent observation of OSR in wild sea turtle populations. This approach allows inference of OSR. Protection of beaches with a higher number of pairs of parents should be prioritised to increase genetic resilience. Conservation actions in rookeries with a female-skewed OSR should be prioritised to address population declines in the long run

Small-scale fisheries of Peru: a major sink for marine turtles in the Pacific

1. Over the last few decades, evidence of marine vertebrate bycatch has been collected for a range of industrial fisheries. It has recently been acknowledged that large impacts may also result from similar interactions with small-scale fisheries (SSF) due largely to their diffuse effort and large number of vessels in operation. Marine mammals, seabirds, turtles as well as some shark species have been reported as being impacted by SSF worldwide. 2. From 2000 to 2007, we used both shore-based and onboard observer programmes from three SSF ports in Peru to assess the impact on marine turtles of small-scale longline, bottom set nets and driftnet fisheries. 3. We reported a total of 807 sea turtles captured, 91Æ8% of which were released alive. For these three sites alone, we estimated c. 5900 turtles captured annually (3200 loggerhead turtles Caretta caretta, 2400 green turtles Chelonia mydas, 240 olive ridleys Lepidochelys olivacea and 70 leatherback turtles Dermochelys coriacea). 4. SSF in Peru are widespread and numerous (\u3e100 ports, \u3e9500 vessels, \u3e37 000 fishers), and our observed effort constituted c. 1% of longline and net deployments. We suggest that the number of turtles captured per year is likely to be in the tens of thousands. Thus, the impacts of Peruvian SSF have the potential to severely impact sea turtles in the Pacific especially green, loggerhead and leatherback turtles. 5. Implications of the human use of turtle products as ‘marine bushmeat’ are also raised as an important issue. Although such utilization is illegal, it is difficult to foresee how it can be managed without addressing the constraints to the livelihoods of those depending almost entirely on coastal resources. 6. Syntheses and applications. Our analysis demonstrates that, despite logistical challenges, it is feasible to estimate the bycatch per unit of effort in SSF by combining methods that account for fishing effort and bycatch, such as using onboard and shore-based observers. We highlight sea turtle bycatch in SSF in the southeast Pacific as a major conservation concern but also suggest possible paths for mitigation

Characteristics of a Green Turtle (Chelonia mydas) Assemblage in Northwestern Florida Determined During a Hypothermic Stunning Event

A hypothermic stunning event (i.e., cold-stunning event) during late Dec. 2000 and early Jan. 2001 involving an unprecedented number of sea turtles provided an opportunity to characterize the green turtle (Chelonia mydas) assemblage in St. Joseph Bay (Gulf County, Florida). In addition to 388 green turtles, the 401 cold-stunned turtles comprised 10 Kemp\u27s ridleys (Lepidochelys kempii) and three loggerheads (Caretta caretta). Most (337/401) of the turtles survived and were eventually released. To place this event in perspective, we categorize sea turtle cold-stunning events in the eastern United States as either acute or chronic. Acute cold-stunning events, like the one in St. Joseph Bay, occur only during unusually cold winters in shallow-water areas (\u3c 2m), where sea turtles are year-round residents. These are short-lived (\u3c 2 wk) events with low mortality rates (\u3c 30%) that affect principally green turtles. Chronic cold-stunning events occur every winter in areas where sea turtles are seasonal residents. These are long-lived (1-3 mo) events with high mortality rates (\u3e 60%) that affect primarily Kemp\u27s ridleys. All of the green turtles from St. Joseph Bay were neritic-phase juveniles, and the mean straight-line carapace length of this group was 36.6 cm (range = 25.0-75.3 cm, SD = 8.9). This assemblage of juvenile green turtles is the first documented along the northern Gulf of Mexico. Sequencing of mtDNA (mitochondrial DNA) from tissue samples taken from 255 of the green turtles revealed that about 81% were from the nesting populations in the United States (Florida) and Mexico (Yucatan). This assemblage is unusual in the United States because it does not have a substantial representation from the nesting population in Costa Rica (Tortuguero), the Atlantic\u27s largest green turtle nesting population. Based on necropsies of 51 of the green turtles, the sex ratio of this assemblage was female-biased (3.25 females: 1 male), which may be a result of warm incubation temperatures on the nesting beaches in Florida. The majority of the material found in the gastrointestinal tracts of the green turtles that died was turtle grass (Thalassia testudinum). This was the first time turtle grass has been identified as the primary diet of juvenile green turtles anywhere in the continental United States. Green turtles in St. Joseph Bay appear to have few direct threats, but the seagrass upon which these turtles primarily forage has suffered extensive damage from boat propellers

Setting Priorities for Space Research: Opportunities and Imperatives

This report represents the first phase of a study by a task group convened by the Space Studies Board to ascertain whether it should attempt to develop a methodology for recommending priorities among the various initiatives in space research (that is, scientific activities concerned with phenomena in space or utilizing observations from space). The report argues that such priority statements by the space research community are both necessary and desirable and would contribute to the formulation and implementation of public policy. The report advocates the establishment of priorities to enhance effective management of the nation's scientific research program in space. It argues that scientific objectives and purposes should determine how and under what circumstances scientific research should be done. The report does not take a position on the controversy between advocates of manned space exploration and those who favor the exclusive use of unmanned space vehicles. Nor does the report address questions about the value or appropriateness of Space Station Freedom or proposals to establish a permanent manned Moon base or to undertake a manned mission to Mars. These issues lie beyond the charge to the task group

Genetic fingerprinting reveals natal origins of male leatherback turtles encountered in the Atlantic Ocean and Mediterranean Sea

This paper is not subject to U.S. copyright. The definitive version was published in Marine Biology 164 (2017): 181, doi:10.1007/s00227-017-3211-0.Understanding population dynamics in broadly distributed marine species with cryptic life history stages is challenging. Information on the population dynamics of sea turtles tends to be biased toward females, due to their accessibility for study on nesting beaches. Males are encountered only at sea; there is little information about their migratory routes, residence areas, foraging zones, and population boundaries. In particular, male leatherbacks (Dermochelys coriacea) are quite elusive; little is known about adult and juvenile male distribution or behavior. The at-sea distribution of male turtles from different breeding populations is not known. Here, 122 captured or stranded male leatherback turtles from the USA, Turkey, France, and Canada (collected 1997–2012) were assigned to one of nine Atlantic basin populations using genetic analysis with microsatellite DNA markers. We found that all turtles originated from western Atlantic nesting beaches (Trinidad 55%, French Guiana 31%, and Costa Rica 14%). Although genetic data for other Atlantic nesting populations were represented in the assignment analysis (St. Croix, Brazil, Florida, and Africa (west and south), none of the male leatherbacks included in this study were shown to originate from these populations. This was an unexpected result based on estimated source population sizes. One stranded turtle from Turkey was assigned to French Guiana, while others that were stranded in France were from Trinidad or French Guiana breeding populations. For 12 male leatherbacks in our dataset, natal origins determined from the genetic assignment tests were compared to published satellite and flipper tag information to provide evidence of natal homing for male leatherbacks, which corroborated our genetic findings. Our focused study on male leatherback natal origins provides information not previously known for this cryptic, but essential component of the breeding population. This method should provide a guideline for future studies, with the ultimate goal of improving management and conservation strategies for threatened and endangered species by taking the male component of the breeding population into account.Sample collection in Nova Scotia, Canada, was supported by funding from Canadian Wildlife Federation, Environment Canada, Fisheries and Oceans Canada, George Cedric Metcalf Foundation, Habitat Stewardship Program for Species at Risk, National Fish and Wildlife Foundation (USA), National Marine Fisheries Service (USA), Natural Sciences and Engineering Research Council of Canada, and World Wildlife Fund Canada. Funding for US samples was provided by National Oceanic and Atmospheric Administration, Massachusetts Division of Marine Fisheries, National Fish and Wildlife Foundation, and Cape Cod Commercial Fisherman’s Alliance. Funding support for this analysis and for Kelly R. Stewart was provided by a Lenfest Ocean Program Grant

Long-term trends in the foraging ecology and habitat use of an endangered species: an isotopic perspective.

Evaluating long-term drivers of foraging ecology and population productivity is crucial for providing ecological baselines and forecasting species responses to future environmental conditions. Here, we examine the trophic ecology and habitat use of North Atlantic leatherback turtles (St. Croix nesting population) and investigate the effects of large-scale oceanographic conditions on leatherback foraging dynamics. We used bulk and compound-specific nitrogen isotope analysis of amino acids (CSIA-AA) to estimate leatherback trophic position (TP) over an 18-year period, compare these estimates with TP estimates from a Pacific leatherback population, and elucidate the pre-nesting habitat use patterns of leatherbacks. Our secondary objective was to use oceanographic indices and nesting information from St. Croix leatherbacks to evaluate relationships between trophic ecology, nesting parameters, and regional environmental conditions measured by the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation. We found no change in leatherback TP over time and no difference in TP between Atlantic and Pacific leatherbacks, indicating that differences in trophic ecology between populations are an unlikely driver of the population dichotomy between Pacific and Atlantic leatherbacks. Isotope data suggested that St. Croix leatherbacks inhabit multiple oceanic regions prior to nesting, although, like their conspecifics in the Pacific, individuals exhibit fidelity to specific foraging regions. Leatherback nesting parameters were weakly related to the NAO, which may suggest that positive NAO phases benefit St. Croix leatherbacks, potentially through increases in resource availability in their foraging areas. Our data contribute to the understanding of leatherback turtle ecology and potential mechanistic drivers of the dichotomy between populations of this protected species

Editorial: Advances in the Biology and Conservation of Marine Turtles

(First Paragraph) Marine turtles have been the subject of research over many decades, inspired by their unique life history and necessitated by their declining populations from a suite of human impacts including direct harvest, bycatch in marine fisheries, pollution, and climate change. Despite this, much about marine turtle biology has remained a mystery (Godley et al., 2008; Rees et al., 2016; Wildermann et al., 2018), but the rate of scientific discovery is increasing rapidly. As research techniques and conservation practices expand, the marine turtle research community has kept abreast of these developments and their application to marine turtles. In this special Research Topic, researchers submitted articles related to cutting-edge work in biology and conservation. The resulting 10 articles bring new insights across marine turtle movement, conservation, and methodological and analytical techniques, as well as other understudied areas and issues