Turtle Fishery Research Articles

Origins of green turtle fishery bycatch in the central pacific revealed by mixed genetic markers

Longline fishing vessels, such as those that target tuna or billfish, also unintentionally catch endangered marine turtle species on the high seas. The stock composition of this bycatch is often unknown but potentially complex, with individuals coming from many possible origins on an ocean-basin scale. To better understand the stock composition of green turtle (Chelonia mydas) bycatch we obtained 46 turtles, 27-91 cm in curved carapace length, caught by Hawaii- and American Samoa-based pelagic longline fishing vessels across large areas of the North- and South-central Pacific. We genotyped these at nine microsatellite loci and one mitochondrial DNA marker, and used a baseline of 1,043 nesting female green turtles from beaches across the Pacific for population assignment and mixed-stock analysis. By analyzing both marker types jointly we were able to increase power and genetically resolve ten baseline stocks of nesting females with mean self-assignment and simulated accuracies of 75-97%. Above the Equator, green turtle bycatch was composed mostly of individuals from Hawaiian and Eastern Pacific stocks, with a small number from the Western Pacific. Below the Equator, the most common stocks in the bycatch were from Australia and the Coral Sea, American Samoa and French Polynesia, and the Galápagos Islands. Overall, turtles originating from East, West, and Central Pacific breeding populations were major components of the bycatch, suggesting that the geographic ranges of these populations overlap across large tracts of ocean during the pelagic life history stages.

Twenty-year changes in the composition of a mixed stock of foraging green turtles in the Yaeyama Islands of Japan

Recent studies have shown an increasing mean straight carapace length (SCL) of foraging green turtles Chelonia mydas around the Yaeyama Islands, Japan, compared to that of 20 yr ago. This trend is attributed to reduced juvenile mortality resulting from a decline in sea turtle fisheries. In this Yaeyama foraging aggregation, the proportions of turtles originating from different populations (genetic stocks) are known to vary according to size; for turtles originating from the Ryukyu Archipelago and Ogasawara (Japanese populations), the proportion in the 50-70 cm SCL size class is higher than that in the <50 cm SCL size class. Here, we compared the natal origin compositions of the Yaeyama foraging aggregation from 2 sampling periods (1997-1999 and 2016-2018) across 2 size categories (<55 and >55 cm SCL) and investigated the relationship between the size increase and changes in natal origins. The results showed that the proportion of the Japanese populations has recently increased compared to that 20 yr ago. The size distribution, based on the natal origin of each turtle in 2016-2018 estimated using single nucleotide polymorphisms, showed that the proportion of populations at latitudes lower than Japan with a ≥55 cm SCL decreased substantially, whereas the proportion of the Japanese populations remained stable between size categories. These results suggest a link between the size increase and the increase in Japanese turtles. This study also provides the detailed composition of the Yaeyama foraging aggregation, including the size distributions and sex ratios of contributing populations.

Saving the sea turtles of Anguilla: Combining scientific data with community perspectives to inform policy decisions

Historic over-exploitation and the more recent threats caused by fisheries by-catch, disease and climate change have left sea turtle populations in the Wider Caribbean at risk of extinction. In 1995, following regional declines in nesting and foraging populations, the island of Anguilla implemented a moratorium on the hunting of turtles. At the request of the Government of Anguilla for scientific data to either support or remove the moratorium, comprehensive population estimates were obtained, and foraging, nesting and migratory movements were examined. In addition, community perspectives on turtles and their protection were assessed. Between 2015 and 18 surveys of 30 nesting beaches estimated low nesting activity with a maximum of 41 hawksbill, 15 green, and 1–2 leatherback turtles nesting in Anguilla annually. The inter-nesting range of hawksbills exhibited high levels of geographic overlap and occurred within 1.5 km of nesting beaches. Migratory tracks of hawksbill turtles traversed through seven exclusive economic zones, two of which allow a legal turtle fishery. Site fidelity was observed in foraging areas of green turtles and genetic analysis revealed population differentiation between green turtle foraging sites in Anguilla and between hawksbill rookeries in Anguilla compared to other Leeward Islands, indicating the individual importance of each foraging and nesting site. The Anguillan public (n = 302) overwhelmingly agreed with the current ban on harvesting sea turtles and considered turtles important for ecotourism. Our work provides a case-study, that can be applied globally, of how scientific research combined with community perspectives can effectively inform policy and ultimately protect endangered species, and highlights that local Governments provided with high quality data in a timely fashion for their policy making timetable are more likely to integrate findings into their decision-making process.

Cayman Islands Sea Turtle Nesting Population Increases Over 22 Years of Monitoring

Given differing trajectories of sea turtle populations worldwide, there is a need to assess and report long-term population trends and determine which conservation strategies are effective. In this study, we report on sea turtle nest monitoring in the Cayman Islands over a 22-year period. We found that green (Chelonia mydas) and loggerhead (Caretta caretta) nest numbers increased significantly across the three islands since monitoring began in 1998, but that hawksbill nest numbers remained low with a maximum of 13 nests recorded in a season. Comparing the first 5 years of nest numbers to the most recent 5 years, the greatest percentage increase in green turtle nests was in Grand Cayman from 82 to 1,005 nests (1,126%), whereas the greatest percentage increase for loggerhead turtle nests was in Little Cayman from 10 to 290 nests (3,800%). A captive breeding operation contributed to the increase in the Grand Cayman green turtle population, however, loggerhead turtles were never captive-bred, and these populations began to increase after a legal traditional turtle fishery became inactive in 2008. Although both species have shown significant signs of recovery, populations remain at a fragment of their historical level and are vulnerable to threats. Illegal harvesting occurs to this day, with multiple females taken from nesting beaches each year. For nests and hatchlings, threats include artificial lighting on nesting beaches, causing hatchlings to misorient away from the sea, and inundation of nests by seawater reducing hatch success. The impacts of lighting were found to increase over the monitoring period. Spatial data on nest distribution was used to identify critical nesting habitat for green and loggerhead turtles and is used by the Cayman Islands Department of Environment to facilitate remediation of threats related to beachside development and for targeted future management efforts.

A Sea Turtle Population Assessment for Florida's Big Bend, Northeastern Gulf of Mexico

Coastal waters of Florida’s Big Bend, Gulf of Mexico (GOM) once supported one of the largest sea turtle fisheries in the United States. To fill an information gap in this region on abundance and distribution of sea turtles, we used vessel—based distance sampling and active capture methods to characterize current foraging aggregations near the St. Martins Marsh Aquatic Preserve. Over 10 sampling periods between 2012—2018, we completed 513 km of transects and recorded 819 turtles among 4 species—green turtle (Chelonia mydas, n = 624), Kemp’s ridley (Lepidochelys kempii, n = 147), loggerhead (Caretta caretta, n = 47), and a single hawksbill (Eretmochelys imbricata). Turtle densities in 4 study plots within the 200 km2 study site ranged from 57—221 immature green turtles/km2, 16—56 immature Kemp’s ridleys/km2, and 1—14 juvenile—to—adult loggerheads/km2. Of 200 green turtles captured, 67.5% showed skin tumors consistent with fibropapillomatosis, a frequency similar to that from urbanized estuaries of Florida’s east coast. The largest green turtles (> 60 cm straight standard carapace length), abundant in the southern portion of our study area, are of note because this size class is uncommonly recorded within US territorial waters. Analyses of green turtle mtDNA haplotypes found contributions from rookeries in the western GOM, Mexican Caribbean, and Costa Rica. Although Big Bend protected areas were principally designed to conserve marine and coastal habitats, these regulatory zones have also effectively encompassed a hotspot for foraging sea turtles.

Spatial Ecology of Sub-Adult Green Turtles in Coastal Waters of the Turks and Caicos Islands: Implications for Conservation Management

Marine turtles are of conservation concern throughout their range, with past population declines largely due to exploitation through both legal and illegal take, and incidental capture in fisheries. Whilst much research effort has been focussed on nesting beaches and elaborating migratory corridors, these species spend the vast majority of their life-cycle in foraging grounds, which are, in some species, quite discrete. To understand and manage these populations, empirical data are needed on distribution, space-use, and habitats in order to best inform design of protective measures. Here we describe space-use, occupancy, and wide-ranging movements derived from conventional flipper tagging and satellite tracking of sub-adult green turtles (Chelonia mydas) within the coastal waters of the Turks and Caicos Islands (TCI; 2011-2017). Sixteen individual turtles of between 63 and 81 cm curved carapace length (CCL) were satellite tracked for a mean 226 days (range: 38-496). Analyses of both satellite tracking and conventional flipper tagging data revealed extended periods of occupancy in the shallow coastal waters within a RAMSAR protected area that includes seagrass beds and algae-rich tidal creeks. Satellite tracking also revealed wide-ranging movements, with four of 16 turtles exhibiting directed movements away (displaced >450 km) from TCI waters travelling through nine geo-political zones within the Caribbean-Atlantic basin, as well as on the High Seas. One turtle travelled to the Central American coast before settling on inshore habitat in Colombia’s waters for 162 days before transmission ceased, indicating ontogenetic dispersal to a distant foraging habitat. These data highlight connectivity throughout the region, displaying key linkages between countries that have previously only been linked by genetic evidence. This study also provides evidence of the importance of the Turks and Caicos Islands marine protected area network and importance of effective management of the sea turtle fishery for regional green turtle populations.

Quantifying local ecological knowledge to model historical abundance of long-lived, heavily-exploited fauna.

Deriving robust historical population trends for long-lived species subject to human exploitation is challenging in scenarios where long-term scientific data are scarce or unavailable, as often occurs for species affected by small-scale fisheries and subsistence hunting. The importance of Local Ecological Knowledge (LEK) in data-poor scenarios is increasingly recognized in conservation, both in terms of uncovering historical trends and for engaging community stewardship of historic information. Building on previous work in marine historical ecology and local ecological knowledge, we propose a mixed socio-ecological framework to reliably document and quantify LEK to reconstruct historical population trends. Our method can be adapted by interdisciplinary teams to study various long-lived taxa with a history of human use. We demonstrate the validity of our approach by reconstructing long-term abundance data for the heavily-exploited East Pacific green turtle (Chelonia mydas) in Baja California, Mexico, which was driven to near extinction by a largely unregulated fishery from the early 1950s to the 1980s. No scientific baseline abundance data were available for this time-frame because recent biological surveys started in 1995 after all green turtle fisheries in the area were closed. To fill this data gap, we documented LEK among local fishers using ethnographic methods and obtained verified, qualitative data to understand the socio-environmental complexity of the green turtle fishery. We then established an iterative framework to synthesize and quantify LEK using generalized linear models (GLMs) and nonlinear regression (NLR) to generate a standardized, LEK-derived catch-per-unit-effort (CPUE) time-series. CPUE is an index of abundance that is compatible with contemporary scientific survey data. We confirmed the accuracy of LEK-derived CPUE estimates via comparisons with fisheries statistics available for 1962–1982. We then modeled LEK-derived abundance trends prior to 1995 using NLR. Our model established baseline abundance and described historical declines, revealing that the most critical (exponential) decline occurred between 1960 and 1980. This robust integration of LEK data with ecological science is of critical value for conservation and management, as it contributes to a holistic view of a species’ historic and contemporary conservation status.

Wayuú capture of green turtles, Chelonia mydas, in the Gulf of Venezuela: A major Caribbean artisanal turtle fishery

Fisheries, either directed or via bycatch, are a major cause of decline in global populations of marine turtles. Although artisanal fisheries are often seen as lower-impact than industrial fisheries, they may be among the most serious threats to green turtles. Between 2005 and 2008, to better understand the impacts of such fisheries in the High Extraction Zone of the Gulf of Venezuela (HEZ-GV), an important feeding habitat for green turtles, we interviewed fishers, observed fishing activities directly, and counted, measured, and marked discarded turtle carapaces at fishing ports and traditional markets. From these, we estimated that at least 3,402 ± 247 turtles/year were extracted with artisanal nets, suggesting that the HEZ-GV artisanal turtle fishery may have been among the most active in the Caribbean at the time, with a CPUE of 0.04 turtles/km-net*hour ±0.014. However, capture was not selective, confirming prior anecdotal information suggesting that this fishery supplies mainly subsistence and not commercial use. Harvested turtles consisted mainly of juveniles (64%, CCLmin = 55.7 cm ± SE 0.9), and subadults (35%, CCLmin = 78.9 cm ± 0.6 cm), with very few adults (1%, CCLmin = 98 cm ± 0.6 cm). Our findings highlight the need for continued monitoring of the artisanal turtle fishery in the HEZ-GV, particularly given the possibility of increased reliance on aquatic bushmeat sources in Venezuela's present socio-economic crisis. More broadly, they also indicate that scientifically based catch guidelines for marine turtles may be just as important in artisanal as in commercial fisheries, to ensure sustainability and mitigate harvest impacts.

Field Data and Stakeholders: Regulating the Commercial Harvest of Snapping Turtles in Maryland

Abstract Turtles are highly susceptible to the negative effects of commercial harvesting. In October 2007, the Maryland Department of Natural Resources convened a Working Group to discuss the snapping turtle (Chelydra serpentina) fishery in Maryland and to make recommendations considered necessary to maintain a sustainable fishery. We collected information on population structure and the collecting techniques used by local harvesters in the field. An increase in the minimum legal size limit from 9.5 inches (24.1 cm) in 2008 to 11 inches (27.9 cm) in 2009 resulted in more females being protected from harvesting yet significantly decreased catch per unit effort, forcing harvesters to increase collecting effort to maintain catch levels.

Illegal capture and black market trade of sea turtles in Pisco, Peru: the never ending story

The Pisco-San Andres area (13°44´S, 76°13´W) in central Peru is known for a traditional historic sea turtle fishery. To determine if illegal captures and black market trade exist, we carried out bi-weekly sampling in dumpsites and coastal areas from 2009 to 2015. A total of 953 carapaces were encountered, which included mainly black turtles ( Chelonia mydas , 92.2%) and to a lesser extent, olive ridley turtles ( Lepidochelys olivacea , 4.3%), leatherback turtles ( Dermochelys coriacea , 1.4%), and a single hawksbill turtle ( Eretmochelys imbricate , 0.1%). The mean curved carapace length (CCL) was 59.1 for black turtles, 60.4 for olive ridleys and 113 cm for leatherbacks. For all species, most of turtles reported were juveniles and came largely from illegal captures (89%) and not from stranding reports (1.4%). Mean mortality was 8.1 carcasses km -1 year -1 at beaches and 160.2 carcasses year -1 at dumpsites. Main consumed prey items in black turtles were silverside fish eggs (47.9%), Chondracanthus seaweed (31.4%) and Paranthus sp., anemone (16.2%). Despite the big sampling effort, mortality estimates could be underestimated since big percentages are butchered and discarded at sea. Still, numbers remains high with almost 1000 turtles in a five-year period and an illegal trade persists. Urgent measures are needed to recover this endangered species.

Reconstructing 290 years of a data‐poor fishery through ethnographic and archival research: The East Pacific green turtle (Chelonia mydas) in Baja California, Mexico

AbstractEvaluating historical changes in the exploitation of marine organisms is a key challenge in fisheries ecology and marine conservation. In the Eastern Pacific, marine turtles were exploited for millennia before systematic monitoring began <50 years ago. Using ethnographic and historical data, we generated a detailed reconstruction of the East Pacific green sea turtle (Chelonia mydas) fishery in Mexico's Baja California peninsula from 1700 to 1990. Sea turtles from the region's important feeding areas were a staple food source from the earliest phases of human occupation, dating back at least 12,000 years. In contrast with regions such as the Caribbean, small human populations and limited market access resulted in apparently sustainable turtle harvests until the second half of the 20th century. We found that the estimated annual catches between 1960 and 1980 exceeded the estimated annual catches of the previous 250 years by an order of magnitude, leading to the collapse of the fishery and the depletion of the green turtle population. A total ban on sea turtle captures in 1990, comprehensive nesting beach protection, and significant conservation efforts resulted in increases in breeding females on nesting beaches and catch rates in scientific monitoring on main feeding grounds since the early 2000s. This provides a positive outlook for this once‐depleted population segment. Although further research is needed to evaluate current conservation status, we have identified a date, between 1950 and 1960, which can serve as a reliable temporal reference for future evaluations of historical baseline abundance in this region.

Change in population structure, growth and mortality rate of juvenile green turtle (Chelonia mydas) after the decline of the sea turtle fishery in Yaeyama Islands, Ryukyu Archipelago

The Yaeyama Islands provide habitat for juvenile green turtles originating from various rookeries in the western Pacific. The sea turtle fishery has been declining since 2004 due to the retirement of sea turtle fishermen in the region. We investigated the population ecology of green turtles based on capture–mark–recapture data from 1995 to 2016. The effect of the past sea turtle fishery on the green turtle population was analyzed by comparing the population structure, growth and mortality rates during 1995–2003, with those of the population in 2004–2016. Mean straight carapace lengths of green turtles in 1995–2003 were 51.5 cm (SD = 10.9, range 34.0–102.4, N = 838), annual growth rates were 2.7 cm year−1 (SD = 1.31, range 0.09–5.32, N = 50), and mortality rates were 0.25 year−1 (95% CI 0.20–0.30). In comparison, mean straight carapace length of green turtles in 2004–2016 was 55.5 cm (SD = 12.1, range 6.2–96.5, N = 595), growth rates were 2.24 cm year−1 (SD = 0.78, range 0.79–4.17, N = 67) and mortality rates were 0.15 year−1 (95% CI 0.11–0.19). Carapace size increased and annual growth and mortality rates decreased after 2004. The increase in the number of larger-sized green turtles and the decrease in mortality rates were likely effects of the decline in the sea turtle fishery.

Incidental capture of sea turtles by industrial bottom trawl fishery in the Tropical South-western Atlantic

The five sea turtle species occurring in Brazilian waters are susceptible to threats, including incidental catches by fisheries. Studies on incidental captures in fishing gears are the main focus of several conservation actions due to high sea turtle fishery mortality worldwide. This study provides the first evaluation of incidental sea turtle catches by industrial bottom trawl fisheries operating in Brazilian waters. Four twin-trawler vessels were monitored between July 2010 and December 2011 by captains who voluntarily completed logbooks. Forty-four turtles were captured during the 1996 tows (8313 fishing hours), resulting in a catch of 5.3 ± 0.8 turtles per 1000 h per unit effort. Captured species included the loggerhead turtle (Caretta caretta, 22 individuals), olive ridley turtles (Lepidochelys olivacea, 21 individuals) and one green turtle (Chelonia mydas). Water depth was the only variable that significantly affected sea turtle captures according to Generalized Linear Models. The capture rates reported in this study ranked sixth in relation to other published studies of similar fisheries occurring worldwide. Considering the importance of this region for sea turtles, the increasing evidence of sea turtle mortality and the goals of the National Action Plan for Conservation of Sea Turtles in Brazil, it is essential to identify the main threats towards these animals and propose mitigating solutions to reduce sea turtle mortality induced by fishing activities. This study provides results that may guide future research and goals in meeting sea turtle conservation strategies.

Taxonomic distinctness in the diet of two sympatric marine turtle species

AbstractMarine turtles are considered keystone consumers in tropical coastal ecosystems and their decline through overexploitation has been implicated in the deterioration of reefs and seagrass pastures in the Caribbean. In the present study, we analysed stomach contents of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) harvested in the legal turtle fishery of the Turks and Caicos Islands (Caribbean) during 2008–2010. Small juveniles to adult‐sized turtles were sampled. Together with data from habitat surveys, we assessed diet composition and the taxonomic distinctness (and other species diversity measures) in the diets of these sympatric marine turtle species. The diet of green turtles (n = 92) consisted of a total of 47 taxa: including three species of seagrass (present in 99% of individuals), 29 species of algae and eight sponge species. Hawksbill turtles (n = 45) consumed 73 taxa and were largely spongivorous (16 species; sponges present in 100% of individuals) but also foraged on 50 species of algae (present in 73% of individuals) and three species of seagrass. Plastics were found in trace amounts in 4% of green turtle and 9% of hawksbill turtle stomach samples. We expected to find changes in diet that might reflect ontogenetic shifts from small (oceanic‐pelagic) turtles to larger (coastal‐benthic) turtles. Dietary composition (abundance and biomass), however, did not change significantly with turtle size, although average taxonomic distinctness was lower in larger green turtles. There was little overlap in prey between the two turtle species, suggesting niche separation. Taxonomic distinctness routines indicated that green turtles had the most selective diet, whereas hawksbill turtles were less selective than expected when compared with the relative frequency and biomass of diet items. We discuss these findings in relation to the likely important trophic roles that these sympatric turtle species play in reef and seagrass habitats.

Fisher choice may increase prevalence of green turtle fibropapillomatosis disease

Disease in wildlife populations is often controlled through culling. But when healthy individuals are removed and diseased individuals are left in the population, it is anticipated that prevalence of disease increases. Although this scenario is presumably common in exploited populations where infected individuals are less marketable, it is not widely reported in the literature. We describe this scenario in a marine turtle fishery in the Turks and Caicos Islands (TCI), where green turtles are harvested for local consumption. During a two-year period, we recorded the occurrence of fibropapillomatosis (FP) disease in green turtles (Chelonia mydas) captured during in-water surveys and compared it with that of turtles landed in the fishery. 13.4% (n=32) of turtles captured during in-water surveys showed externally visible signs of FP. FP occurred at specific geographic locations where fishing also occurred. Despite the disease being prevalent in the size classes selected by fishers, FP was not present in any animals landed by the fishery (n=162). The majority (61%) of fishers interviewed expressed that they had caught turtles with FP. Yet, 82% of those that had caught turtles with the disease chose to return their catch to the sea, selectively harvesting healthy turtles and leaving those with the disease in the population. Our study illustrates that fisher choice may increase the prevalence of FP disease and highlights the importance of this widely neglected driver in the disease dynamics of exploited wildlife populations.

Protecting the breeders: research informs legislative change in a marine turtle fishery

Marine turtles are sensitive to harvesting because of life-cycle traits such as longevity, late maturity and natal philopatry. The take of nesting females is of conservation concern because they are key to population maintenance and has led to global efforts to protect this life stage. In the Turks and Caicos Islands (TCI; a UK Overseas Territory in the Caribbean), previous turtle fishery legislation protected nesting turtles on the beach but not in the water, where turtles over a minimum size were subject to legal take. In a 2-year study, we undertook nesting beach and in-water surveys, molecular analyses, satellite tracking and collation of fisheries landing data to investigate the populations of green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles in the TCI and its turtle fishery. Adults were frequently taken in one of the region’s largest legal and artisanal turtle fisheries. We suggest that nesting populations in the TCI, which contain genetically unique haplotypes, have diminished since the 1980s, likely as a result of the harvest of adults. Using these multiple lines of evidence, we highlight the inadequacies of the former fishery regulations and propose specific legislative amendments, which, as a result of this study, were implemented on 1 July 2014 by the TCI government. With good enforcement, these measures will protect adults breeding in the TCI and those from nesting rookeries in the region that use the waters of the TCI, improve the management of this fishery, and safeguard fisher livelihoods.

So excellent a fishe: a global overview of legal marine turtle fisheries

AbstractAimWe provide a global assessment of the current legal direct take of marine turtles, including the scale and species breakdown at country level, and investigate the significance of legal take to marine turtle populations within the wider context of global threats.LocationWorld‐wide.MethodsWe undertook a comprehensive review of the literature (> 500 publications) and contacted over 150 in‐country experts to collate data for countries that permit the legal take of marine turtles (as of 1 January 2013). Current annual take for each country and species was estimated, and estimates were generated for the 1980s, 1990s and 2000s.ResultsCurrently, 42 countries and territories permit direct take of turtles and collectively take in excess of 42,000 turtles per year, the majority of which (> 80%) are green turtles Chelonia mydas (Linnaeus 1758). Ten countries account for more than 90% of legal take each year with Papua New Guinea (36.1%) and Nicaragua (22.3%) accounting for more than half of the total global take. Since 1980, we estimate that more than 2 million turtles have been legally taken in these countries, with current levels < 60% of those in the 1980s.Main conclusionsOur results provide the most comprehensive global synthesis of the legal take of turtles in recent years and suggest that legal take has the potential to be a driver of marine turtle population dynamics, comparable to mortality estimates through recorded bycatch. However, it is likely that illegal take, along with bycatch, is significantly under‐recorded and far greater than the total level of directed legal take. This hampers the ability to assess the relative impacts of these threats to marine turtles.

Chain of commercialization of Podocnemis spp. turtles (Testudines: Podocnemididae) in the Purus River, Amazon basin, Brazil: current status and perspectives

BackgroundConsumption of turtles by natives and settlers in the Amazon and Orinoco has been widely studied in scientific communities. Accepted cultural customs and the local dietary and monetary needs need to be taken into account in conservation programs, and when implementing federal laws related to consumption and fishing methods. This study was conducted around the Purus River, a region known for the consumption and illegal trade of turtles. The objective of this study was to quantify the illegal turtle trade in Tapauá and to understand its effect on the local economy.MethodsThis study was conducted in the municipality of Tapauá in the state of Amazonas, Brazil. To estimate turtle consumption, interviews were conducted over 2 consecutive years (2006 and 2007) in urban areas and isolated communities. The experimental design was randomized with respect to type of household. To study the turtle fishery and trade chain, we used snowball sampling methodology.ResultsDuring our study period, 100% of respondents reported consuming at least three species of turtles (Podocnemis spp.). Our estimates indicate that about 34 tons of animals are consumed annually in Tapauá along the margins of a major fishing river in the Amazon. At least five components related to the chain of commercialization of turtles on the Purus River are identified: Indigenous Apurinã and (2) residents of bordering villages (communities); (3) of local smugglers buy and sell turtles to the community in exchange for manufactured goods, and (4) regional smugglers buy in Tapauá, Lábrea, and Beruri to sell in Manaus and Manacapuru; Finally, (5) there are professional fishermen.ConclusionsWe quantify the full impact of turtle consumption and advocate the conservation of the region’s turtle populations. The Brazilian government should initiate a new turtle consumption management program which involves the opinions of consumers. With these measures the conservation of freshwater turtles in the Brazilian Amazon, is possible.

Historical commercial exploitation and the current status of Hawaiian green turtles

Biodiversity conservation is often limited by short-term records of abundance, geographic distribution, and population dynamics. Historical information can provide a context for assessing current population status and defining recovery, especially for populations recovering from chronic human overexploitation. Here we analyze three decades (1948–1974) of commercial landings from a green turtle fishery in the Hawaiian Islands. Artisanal and commercial overharvesting drove the population to its listing under the U.S. Endangered Species Act in 1978, but the population has since increased and its recovery is being debated. While this turtle fishery was small in scale – with a limited effort, productivity, and revenue – we find dramatic declines in catch per unit effort and a spatial progression that strongly suggest rapid local population depletion. Harvests initially targeted coastal areas near commercial markets but quickly shifted to exploit more remote areas, expanded effort, and increasingly relied on more extractive gears. Additional analyses of economic data, restaurant menus, and expert interviews indicate the fishery was driven by limited, local demand. The seemingly incommensurate scale of the fishery and its impacts reveal the Hawaiian green turtle population was already significantly depleted when commercial fishery began. We describe how historical studies can inform conservation management, including population assessments.

Marine turtle harvest in a mixed small-scale fishery: Evidence for revised management measures

Small-scale fisheries (SSF) account for around half of the world's marine and inland fisheries, but their impact on the marine environment is usually under-estimated owing to difficulties in monitoring and regulation. Successful management of mixed SSF requires holistic approaches that sustainably exploit target species, consider non-target species and maintain fisher livelihoods. For two years, we studied the marine turtle fishery in the Turks and Caicos Islands (TCI) in the Wider Caribbean Region, where the main export fisheries are queen conch (Strombus gigas) and the spiny lobster (Panulirus argus); with fin-fish, green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) taken for domestic consumption. We evaluate the turtle harvest in relation to the other fisheries and recommend legislation and management alternatives. We demonstrate the connectivity between multi-species fisheries and artisanal turtle capture: with increasing lobster catch-per-unit-effort (CPUE), hawksbill catch increased whilst green turtle catch decreased. With increasing conch CPUE, hawksbill catch declined and there was no demonstrable effect on green turtle catch. We estimate 176–324 green and 114–277 hawksbill turtles are harvested annually in TCI: the largest documented legal hawksbill fishery in the western Atlantic. Of particular concern is the capture of adult turtles. Current legislation focuses take on larger individuals that are key to population maintenance. Considering these data we recommend the introduction of maximum size limits for both species and a closed season on hawksbill take during the lobster fishing season. Our results highlight the need to manage turtles as part of a broader approach to SSF management.