Capture Of Turtles Research Articles

Struggles beneath the waves: Unveiling the incidental capture of sea turtles by artisanal fisheries in Angolan waters

The modernization and intensification of fishing practices have raised the threat to sea turtles, with escalating unintentional captures endangering turtles of all life stages. In this study, we examined the impact of artisanal fishing on sea turtles in two coastal regions of Angola, southern Africa. Between August 2015 - March 2016, through participatory monitoring (n = 8) and interviews with fishers (n= 41), we documented unintentional turtle captures occurring year-round during fishing activities. A total of 405 turtles, 403 olive ridley (Lepidochelys olivacea) and 2 green (Chelonia mydas), were caught in gillnets by fishers engaged in participatory monitoring. Net characteristics, including length and proximity to the shoreline, as reported by the interviewed fishers, correlated with those used by the monitoring group. We estimated approximately 1219 turtles captured by the 41 interviewed fishers over the 8-month study period. Most captures occurred within 100 m from the shoreline. The likelihood of accidental turtle captures increased significantly with proximity to the beach, larger mesh sizes, and greater net lengths and number of hauls. We calculated a survival rate of 41%, and a mortality rate of 59% for captured turtles. Number of turtles caught as bycatch varied throughout the year, with the highest Catch Per Unit Effort (CPUE) reported for Oct. – Dec. Since this period aligns with the nesting season, most captured turtles are likely to be females. The high mortality rate reported in this study emphasizes the immediate threat posed by accidental captures to sea turtle populations, underscoring the critical importance of conservation efforts, particularly in artisanal gillnet fisheries.

Traditional Knowledge on the use of Turtles in a Protected Area of the Amazon in Maranhão (Brazil): A Conservation Proposal

The use of turtles for food or breeding is a traditional practice in the Baixada Maranhense Environmental Protection Area (EPA), which is composed of wetlands of high conservation value. However, species such as Kinosternon scorpioides, a semi-aquatic Amazon turtle , are threatened by direct harvesting and habitat loss. Local knowledge of biodiversity has been used to understand these practices and to control these problems as a theoretical basis in research on the use and management of natural resources and conservation. This work aimed to analyze the traditional knowledge of riverside communities on the biology, habitat, capture methods, forms of use, and conservation of turtles in the Baixada Maranhense. Data were collected through semi-structured interviews with inhabitants of riverside communities. Based on our results, turtle species are commonly caught in fishing activities (54.71 percent of the interviewees) or by burning (32.35 percent), a practice with great environmental impacts. 41.77 percent of respondents capture these animals for consumption and prefer the K scorpioides, which also has cultural and medicinal importance for the riverside communities. 89 percent of the interviewees report no knowledge of either the structure and function of an EPA or how resource management works, compromising the sustainability principles and operation of this Conservation Unit (C.U.). It is concluded that capture of turtles is one of the reasons for the decrease in natural stocks of K scorpioides. Strategies for management and conservation of the Baixada Maranhense EPA resources are proposed.

Incidental capture of sea turtles in the Northeast Atlantic Portuguese pelagic longline fishery

Incidental catch or bycatch of sea turtles by pelagic longline fisheries is a major concern worldwide. The Northeast Atlantic hosts key foraging and developmental areas for oceanic juvenile loggerhead sea turtles (Caretta caretta) originating mainly from the Southeastern USA and Cape Verde. This region may be one of the most heavily fished areas by pelagic longline for which no recent assessments of fisheries interactions exist. We analysed fishery observer data collected between 2015 and 2020 to assess sea turtle bycatch by Portuguese commercial longliners targeting swordfish (Xiphias gladius) and blue shark (Prionace glauca) in the Northeast Atlantic. A total of 177 sea turtles interacted with the gear during the 896 fishing sets (887,641 hooks) monitored. Loggerheads (n = 139) ranging between 32 and 78 cm curved carapace length (CCL) were caught at a rate of 0.152 turtles per 1000 hooks, and leatherbacks (Dermochelys coriacea; n = 38) between 100 and 210 cm estimated length at a rate of 0.043 turtles per 1000 hooks. Loggerhead and leatherback bycatch shows a clear seasonal pattern in the region. At haul-back mortality rates of oceanic-stage juvenile loggerheads was estimated at 26% whereas no at haul-back mortality was registered for leatherback turtles. Model estimates, based on AIS derived fishing effort from Global Fishing Watch, indicate a total of 1439 interactions (552–3069 BCI) for loggerhead, and 604 interactions (262–1129 BCI) for leatherback turtles between 2016 and 2020. Information from this study is essential to support effective management strategies for sea turtle conservation in the Northeast Atlantic.

By-catch of sea turtles in Pacific artisanal fishery: Two points of view: From observer and fishers

Fisheries bycatch is a primary driver of population declines in marine megafauna. These captures not only have environmental impacts, they also have economic consequences for fishers such as direct losses when repairing fishing gear. Therefore, evaluating the fishers’ perception of bycatch and comparing it with data from scientific fisheries observers might provide a broader view of the current situation these species face. To do this, we obtained data concerning the bycatch of 1,838 sea turtles between 2008-2018 in the Eastern Pacific Ocean as well as informative surveys from 421 artisanal fishers surveyed in 2020. There is a discrepancy between the bycatch observed and the fishers’ perceptions of it. The observers’ results identified that high rates of incidental capture of sea turtles are associated with the mahi mahi fishery that occurs during winter and is a shallow set fishery using fish as bait. The olive ridley turtle was the main species affected by bycatch. According to the fishers’ perception, bycatch was higher with the use of J-hooks and a longline (compared to circle hooks and to gill nets and trawl nets) and when the target species are pelagic fish during the winter season. In addition, the fishers’ perception showed that 39.4% considered incidental fishing as an environmental problem and 28.5% considered it as a nuisance, while 32.1% do not consider sea turtle bycatch as a problem. These findings suggest that 60% of fishers do not consider it a need to protect sea turtles. Given the different responses between fisheries observers and fishers’ perception, it is clear that more dialogue is necessary to raise awareness about the effects of bycatch on worldwide sea turtle populations. Thus, there is an enormous potential to recruit/increase fishers’ active participation for turtle protection. In this context, the idea of including the fishers’ perception into any management strategy or conservation measure should be reinforced in order to effectively reduce the bycatch of these iconic species.

Survival outcomes of rehabilitated riverine turtles following a freshwater diluted bitumen oil spill

Rehabilitation is often used to mitigate adverse effects of oil spills on wildlife. With an increase in production of alternatives to conventional crude oil such as diluted bitumen (dilbit), emergency spill responders and wildlife rehabilitators need information regarding the health and survival of free-ranging vertebrates exposed to dilbit under natural conditions. In 2010, one of the largest freshwater oil spills in the United States occurred in the Kalamazoo River in Michigan, when over 3.2 million liters of spilled dilbit impacted 56 km of riverine habitat. During 2010 and 2011 cleanup efforts, thousands of northern map turtles (Graptemys geographica) were captured from oiled stretches of the river, cleaned, rehabilitated, and released. We conducted extensive mark-recapture surveys in 2010, 2011, and 2018–2021, and used this dataset to evaluate the monthly survival probability of turtles 1–14 months post-spill and 8–11 years post-spill based on whether turtles were temporarily rehabilitated and released, overwintered in captivity and then released, or were released without rehabilitation. We found that rehabilitated or overwintered turtles had a higher probability of survival 1–14 months post-spill than non-rehabilitated turtles; however, 8–11 years post-spill the among-group differences in monthly survival probability had become negligible. Additionally, following the oil spill in 2010, nearly 6% of northern map turtles were recovered dead, died during rehabilitation, or suffered injuries that precluded release back into the wild. Our results demonstrate that exposure to dilbit in free ranging turtles causes direct mortality, while effort spent on the capture and rehabilitation of oiled freshwater turtles is important as it increases monthly survival 1–14 months post-spill.

Sea Turtle Protection: A Case Study of Protected Sea Turtle Capture in Gunungkidul Regency, Indonesia

This paper aims to discuss the legal process for capturing protected turtles in Gunungkidul Regency and the rescued green turtle’s background. This research uses a socio-legal approach. Data were collected using in-depth interviews and observation and analyzed qualitatively. The result shows: first, the process of catching turtles carried out by community members is strictly enforced. The Natural Resources Conservation Agency of Yogyakarta Special Region submitted the turtle arrest case to police investigators for further investigation. Whatever reasons people put forward, it doesn’t stop the police from strictly enforcing the turtle capture case. Second, the background of the capture of green turtles is due to the lack of public awareness and concern about the importance of turtles as endangered species that are protected and should not be caught. In this case, the regulations regarding the protection and prohibition of capturing turtles are complete, but the local communities often violate them. The results suggest a need to strengthen local communities to understand the importance of protecting turtles as endangered species and strict sanctions for turtle capture. It is not only to establish the education community but also to empower the community to provide the initial information to the investigators if it is found the violation of the Act on the turtles protection.

Nonlethal capture of green sea turtles (Chelonia mydas) in fishing weirs as an opportunity for population studies and conservation

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.

Incidental capture of sea turtles in southeast Brazil: Assessment of the perceptions of artisanal fishers

Incidental capture of sea turtles in fisheries is the main cause of sea turtle population decline worldwide. This study evaluated the interactions between fisheries and sea turtles based on the perceptions of fishers operating along the coast of Rio de Janeiro State, southeast Brazil. Between 2016 and 2018, 240 ethnographic interviews were conducted in ten fishing communities, and the indication of incidental captures of sea turtles was high (>75%). Chelonia mydas was the most-observed and most-captured turtle species in the fisheries. The types of fishing gear responsible for such captures were the gillnet, bottom trawl net and hooked line. Most of the fishers reported that it is not possible to avoid incidental captures but that the sea turtles do not die immediately. In general, fishers release the captured animals, regardless of their physical condition (alive, apparently dead or dead). The results demonstrate that both the dissemination of information and training are necessary for greater conservation and efficiency in the handling of sea turtles captured in fishing gear.

High mortality rates of Chelonia mydas in a small‐scale bottom gillnet fishery in the south‐west Atlantic Ocean

Abstract In Brazil, five species of sea turtles use the region for feeding and reproduction. For these endangered species, one of the biggest impacts on their populations is incidental catches in fishing gear. In the state of Santa Catarina (SC) ‐ Brazil, fishing is an important economic activity, with distinct and numerous industrial and artisanal fleets. These fleets incidentally capture all five species of sea turtle. In the Canoa beach fishing community in the municipality of Barra Velha (SC), gillnet fishing holds great economic and cultural importance. The four main gillnet fisheries in this community are whitemouth croaker, leatherjacket/mackerel, hake, and grouper/catfish/flounder, the latter of which is carried out on rocky bottoms and is locally called ‘malhão’. In this fishery, fishermen have reported catching sea turtles over the years, especially the green turtle Chelonia mydas. In the present study, 1,998 sets were monitored between September 2010 and April 2011, of which 104 (5.2%) were of gillnets for whitemouth croaker Micropogonias furnieri; 324 (16.2%) were for leatherjackets Oligoplites spp. and mackerel Scomberomorus spp.; 1,261 (63.1%) were for hake Cynoscion spp.; and 309 (15.5%) were for grouper Epinephelus spp., catfish Genidens spp., and flounder Paralichthys spp. Considering all fisheries, the incidental capture of sea turtles occurred in only 3% of the monitored sets. In all, 87 sea turtles were captured, 78 (89.6%) of which were recorded in the ‘malhão’. Of these captures, 68 (87.2%) were C. mydas, eight (10.2%) were loggerhead turtle Caretta caretta and two (2.6%) were ‘hard‐shelled’ turtles. The direct mortality rate observed for C. mydas in the ‘malhão’ was 73.5%, which is the highest rate recorded in similar fisheries of the south‐west Atlantic, thus raising concern for the protection of this species in the Atlantic Ocean.

Evaluating protected species bycatch in the U.S. Southeast Gillnet Fishery

Incidental capture or ‘bycatch’ of non-targeted species is a global fisheries issue that threatens ocean ecosystems and the conservation and recovery of protected species. Many protected species are at a high risk of incidental capture and mortality in commercial fisheries, which could have an impact on already decreasing populations. From 1998 to 2017, U.S. federal fisheries observers aboard fishing vessels in the U.S. Southeast Gillnet Fishery collected data on captures of encountered protected species. Data collected by the observers were used to describe protected species incidental capture within this fishery. A generalized linear zero-inflated negative binomial two-part model (GLM-ZINB) was applied to determine which environmental and fishing characteristic factors influence the probability of incidental capture of protected species including leatherback, Dermochelys coriacea, and loggerhead, Caretta caretta, sea turtles, bottlenose dolphins, Tursiops truncatus, and giant manta ray, Manta birostris. While a variety of factors were considered in our models, no one single factor was found to influence all protected species. Incidental capture of leatherback turtles was influenced by season, depth, and gillnet depth, while loggerhead turtles were influenced by season, sea surface temperature, and target species of the fishery. Bottlenose dolphin bycatch was most influenced by soak duration, gear type, and season, while giant manta ray captures were influenced by soak duration, gear type, and depth. Environmental factors and fishing characteristics associated with incidental capture of protected species can be used to help guide fishery managers as to what species-specific regulations could be implemented to help mitigate capture.

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.

Selectivity of Two Commercial Dredges Fished in the Northwest Atlantic Sea Scallop Fishery

Size selectivity curves were estimated for two commercial dredge configurations used in the United States Atlantic sea scallop (Placopecten magellanicus) fishery. Traditionally, the New Bedford Style dredge (New Bedford dredge) has been used by the commercial fleet; however, since 2013, the Coonamessett Farm Turtle Deflector Dredge (turtle dredge) has been required seasonally in the Mid-Atlantic region to minimize the capture of sea turtles. This analysis provides estimates of selectivity and relative efficiency for the turtle dredge and the New Bedford dredge. Selectivity information for the turtle dredge is currently unknown, and selectivity for the New Bedford dredge was originally assessed in 2008. The Share Each Lengths Catch Total method was used to model scallop catch-at-length data for each commercial dredge with data collected during the Virginia Institute of Marine Science fishery-independent surveys in 2015 to 2017, conducted onboard commercial fishing vessels. The surveys were conducted in the Mid-Atlantic and Georges Bank regions of the resource in three distinct areas. A paired study design was used, where a nonselective National Marine Fisheries Service sea scallop survey dredge and either the turtle dredge or New Bedford dredge were towed simultaneously at each survey station. To assess for time-varying changes in selectivity, results were compared with the 2008 New Bedford dredge analysis. Results indicated the 50% retention length was 98.2 mm, with a selection range of 28.2 mm and a relative efficiency of 0.83 for the turtle dredge. New Bedford dredge results estimated a 50% retention length of 107.4 mm, selection range of 50.5 mm and relative efficiency of 0.81. Comparing selectivity profiles for the turtle dredge and New Bedford dredge with the 2008 results indicated a shift toward increased retention probability for smaller size classes of scallops.

Incidental capture and mortality of sea turtles in the industrial double‐rig‐bottom trawl fishery in south‐eastern Brazil

Abstract Incidental capture by fisheries is one of the principal threats to sea turtles. This study analysed spatial and temporal patterns of sea turtle bycatch, and estimated the direct initial mortality rate of these animals, in the industrial double‐rig‐bottom trawl fishery in south‐eastern Brazil. This is also the first attempt to relate bycatch/at‐sea mortality in bottom trawling to stranded turtles found along the adjacent coast. The fishery was monitored from October 2015 to April 2018 through data collected voluntarily by the captains of eight industrial double‐rig trawlers. Two hundred and one sea turtles were captured during 9362 tows (43,657.52 trawling hours), resulting in a catch per unit effort (CPUE) of 0.0025 ± 0.0032 turtles h−1 with a standard net of 30.5 m headrope, with no significant difference between the estimated CPUEs for licensed shrimp and demersal fish trawlers. Caretta caretta (52.24%) and Lepidochelys olivacea (38.81%) were the most frequently captured species. According to Generalized Linear Models, C. caretta bycatch was significantly higher during winter, at lower latitudes (−24° to −23°) and higher longitudes (−42° to −40°), while the L. olivacea bycatch was significantly higher at higher latitudes (−23° to −21°). The direct initial mortality rate of sea turtles in the shrimp trawlers was 7.65 ± 3.85%. However, none of the dead individuals subsequently released with plastic tags (n = 10) were found stranded on the coast. Mortality was not significantly related to the depth or duration of the trawling. The results of this study suggest the need for improvements to the current management of the bottom trawl fishery in Brazil, moving from a species‐based to a spatial and seasonal‐based approach. There is also a need to develop turtle excluder devices adapted to local fishing conditions.

Ecotourism based on the observation of sea turtles – A sustainable solution for the touristic promotion of são tomé and príncipe

Wildlife-based ecotourism has been stated as an efficient tool to promote the conservation of endangered species and habitats. These activities also aim to create economic revenue for local communities. Likewise, ecotourism, intends to involve these communities in the management of the conservation programs and develop educational activities, either for children, locals, or tourists, in order to increase awareness about target species and habitats. This study addressed the recent ecotourism activities in the observation of sea turtles which are being developed in São Tomé and Príncipe. These charismatic marine reptiles are vulnerable or endangered due to human activities, such as meat and egg consumption, illegal trade, habitat loss, climatic change, pollution and fisheries bycatch. Therefore, ecotourism using flagship species, like a sea turtle, establishes a sustainable alternative to destructive activities, promoting the country’s environmental, economic and social development, the three pillars of sustainability. In this context, the objective of this study is to know the potential of São Tomé and Príncipe as a turtle watching-based ecotourism destination. An exploratory analysis was carried out through two questionnaires (one focused to the Morro Peixe’s local community and another to the tourists that were engaged in turtle watching activities), in order to know the perception of the inhabitants and tourists regarding the programs and initiatives for the conservation of sea turtles. Despite the awareness that already exists among inhabitants regarding the conservation of sea turtles, the results showed that they do not straightforwardly accept the prohibition for the capture of sea turtles, but most of the population of Morro de Peixe is receptive to changes in the community regarding their protection. In fact, the population is beginning to recognize that tourism, due to the protection given to these endangered species, may become (in the medium term) a sustainable source of income. Regarding tourists’ profile, these are mostly Portuguese, with a high level of education and income. They are well informed about the need for sea turtle conservation and seek to carry out tourism activities that pursue this protection. In fact, this also demonstrates the potential the country has as a turtle watching-based ecotourism destination.

Preliminary data on the occurrence of marine turtles in the Laje de Santos Marine State Park (SP, Brazil)

Abstract Although marine turtles have always been observed by divers, there are few scientific works on marine turtles in the Laje de Santos Marine State Park (PEMLS). Diurnal (bimonthly) and nocturnal (biannual) surveys were conducted between 2013 and 2015 for a more comprehensive study, totalizing 42 hours of diurnal observations and the capture of 41 turtles during nocturnal dives. During the diurnal surveys, visual observations were made from two land based sites (Paredão da Face Sul and Portinho). The numbers of heads (heads observed whether they are of the same turtle or not) and turtles (individuals observed in groups) were counted. The results showed the presence of marine turtles throughout the year. More turtles were observed from Paredão da Face Sul than from Portinho, the latter being a more sheltered point and a site preferred by divers. The nocturnal surveys consisted of the capture of turtles through scuba diving so they could be measured and weighed and tagged according to the guide-lines of the TAMAR project. Four nocturnal surveys were conducted and in the last survey three tagged turtles were captured, two of them having been tagged during this study. The measurements of these turtles indicated their growth during the study period.The present survey also highlighted the importance of the PEMLS as a feeding area for juvenile marine turtles.

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

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.

Incidental capture of sea turtles in the artisanal gillnet fishery in Sechura Bay, northern Peru

Gillnets are recognized globally as one of the fishing gears with the highest levels of bycatch and mortality of sea turtles. Through onboard observer monitoring from July 2013 to June 2014 we assessed the bycatch of sea turtles by an artisanal gillnet fishery operating from Sechura Bay, Peru. One hundred and four sea turtles were incidentally caught in 53 observed fishing sets. The observed species composition of bycatch was green turtle Chelonia mydas (n = 100), hawksbill Eretmochelys imbricata (n = 3) and olive ridley Lepidochelys olivacea (n = 1). Bycatch occurred in 62.3% of monitored sets, with an average of 1.96 turtles caught per set. For all sea turtles combined, 28.8% of individuals were dead and 71.2% were alive at the time of retrieval. The majority of individuals caught were classified as juveniles and sub-adults, with an average carapace length (CCL) of 57.3 ± 0.9 cm for green turtles and 40.2 ± 2.4 cm for hawksbills. The mean annual catch per unit effort (CPUE) of sea turtles was 1.11 ± 0.31 turtles km -1 12 h -1 ), but varied by seasons. These results suggest that Sechura Bay is an important developmental habitat for juvenile and sub-adult green turtles and hawksbill turtles, but one subject to intense fishing interaction pressure. The development of monitoring programs, local awareness-raising activities, and enhanced management and protection of this critical foraging area and developmental habitat is recommended.

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.

Long-term trends in abundance of green sea turtles (Chelonia mydas) assessed by non-lethal capture rates in a coastal fishery

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.

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.