Turtle Mortality Research Articles

An empirical relationship between sea surface temperature and massive stranding of the loggerhead turtle (Caretta caretta) in the Gulf of Ulloa, Mexico

Two mass stranding events of loggerhead sea turtles (Caretta caretta) in the vicinity of the Gulf of Ulloa, Baja California Sur, Mexico, were analyzed during 2003-2006 and 2012-2014. Stranding events were related to the accumulation of consecutive days with lower sea surface temperature (SST) series for the corresponding periods using Pearson correlations. Our results showed that in both periods, a significant cross-correlation was observed between mass stranding and accumulation of consecutive days with temperatures below 18, 17, and 16°C, with a time lag of three to five months. Numerical evidence supports the hypothesis that although the loggerhead turtle mortality is caused by multiple factors under extreme cold events, the environment turns markedly unfavorable for these organisms. Side-effects on health and swimming behavior of the species C. caretta, compromise their ability to avoid obstacles or flee from predators, thus increasing their vulnerability to sickness or lethargy, and possibly leading to the massive stranding of weakened individuals or dead bodies to the beaches of the Gulf of Ulloa. Hence, while SST may not be the direct cause of turtle mortality, it can be a determining factor for the survival of this species.

Skeletochronology, age at maturity and cause of mortality of loggerhead sea turtles Caretta caretta stranded along the beaches of Campania (south-western Italy, western Mediterranean Sea)

Information on demographic and life-history traits of endangered vertebrate species, such as sea turtles, is crucial for planning management and conservation actions. We applied skeletochronology of phalanges to estimate the age of loggerhead turtles, Caretta caretta, found dead stranded along the beaches of Campania (western Mediterranean) from 2013 to 2017. To obtain maturity data, we examined gonads from a subsample of 7 males and 11 females. Overall, curved carapace length (CCL) ranged from 5.6 to 90.8 cm, but for most turtles (89%) it was 50–79.9 cm. Predominance of stranded females (62%) was recorded. Ten out of the eighteen histologically examined gonads allowed estimating maturity. Based on the lines of arrested growth counting, the estimated age of the examined specimens ranged from 0 (hatchling) to 26 years. The modal age was 14 years for males and 17 years for females. The smallest male with spermatogenetic activity had a CCL of 65 cm and was estimated to be 16 years old. The smallest female with follicular development stage, characterising the transition towards adulthood, had a CCL of 69.5 cm and was estimated to be 20 years old. Anthropogenic factors were responsible for 36% of the mortality of individuals, followed by parasitic/infective pathologies (20%).

Virginia Beached Sea Turtle Survey

Sea turtles around the world are threatened with extinction, largely due to human activities. To better protect sea turtles, we need to improve our understanding of the activities that threaten them. However, we often do not know the cause of sea turtle deaths, making it difficult to help protect them. This is the case in the Chesapeake Bay, USA, where hundreds of dead sea turtles are found washed up on beaches each year. In this study, researchers investigated these events, known as sea turtle strandings, to better understand why sea turtles in this region are dying. First, they carried out experiments to predict when and where sea turtles died at sea. This information was then used to identify potential causes of sea turtle mortality. The results of the study suggest that high sea turtle mortality occurs at the entrance of the Bay, where many human activities take place.

On-board study of gas embolism in marine turtles caught in bottom trawl fisheries in the Atlantic Ocean

Decompression sickness (DCS) was first diagnosed in marine turtles in 2014. After capture in net fisheries, animals typically start showing clinical evidence of DCS hours after being hauled on-board, often dying if untreated. These turtles are normally immediately released without any understanding of subsequent clinical problems or outcome. The objectives of this study were to describe early occurrence and severity of gaseous embolism (GE) and DCS in marine turtles after incidental capture in trawl gear, and to provide estimates of on-board and post-release mortality. Twenty-eight marine turtles were examined on-board fishing vessels. All 20 turtles assessed by ultrasound and/or post-mortem examination developed GE, independent of season, depth and duration of trawl and ascent speed. Gas emboli were obvious by ultrasound within 15 minutes after surfacing and worsened over the course of 2 hours. Blood data were consistent with extreme lactic acidosis, reduced glomerular filtration, and stress. Twelve of 28 (43%) animals died on-board, and 3 of 15 (20%) active turtles released with satellite tags died within 6 days. This is the first empirically-based estimate of on-board and post-release mortality of bycaught marine turtles that has until now been unaccounted for in trawl fisheries not equipped with turtle excluder devices.

Anthropogenic mortality and morbidity of marine turtles resulting from marine debris entanglement and boat strikes along the eastern coast of the United Arab Emirates

Anthropogenic mortality and morbidity of marine turtles resulting from marine debris entanglement and boat strikes along the eastern coast of the United Arab Emirates

A pilot study on molecular diagnosis of Hapalotrema mistroides (Digenea: Spirorchiidae) infection in blood samples of live loggerhead turtles Caretta caretta

BackgroundParasites of the family Spirorchiidae cause disease and mortality in marine and freshwater turtles; two species, Hapalotrema mistroides and Neospirorchis sp., are reported in the resident population of loggerhead turtles of the Mediterranean Sea, with the first being the most widespread. In vivo diagnosis of spirorchidiasis can represent a challenge in guaranteeing prompt control and treatment of the disease and is currently limited to copromicroscopy.The aim of this study was the development of a real time PCR assay with TaqMan probe for the detection of H. mistroides infection in the blood of live loggerhead turtles, Caretta caretta, hospitalized in rehabilitation centres. Its potential use for in vivo diagnosis is explored.ResultsThe developed real time PCR successfully detected H. mistroides DNA from both positive controls and experimental blood samples of live loggerhead sea turtles, showing good specificity, sensitivity and good reaction efficiency. Two out of three turtles which had demonstrated positivity at copromicroscopy also tested positive to this blood assay; DNA of H. mistroides was detected within the blood of one sea turtle, which tested negative for copromicroscopy.ConclusionsThis study describes a specific and rapid molecular assay to detect H. mistroides infection from live sea turtles and highlights for the first time the presence of DNA of this species in turtle blood samples. Since this assay is able to detect low amounts of the parasitic free DNA in blood samples, its application could be helpful for in vivo diagnosis of H. mistroides infection as well as for epidemiological purposes.

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.

Mortality in Three-Toed Box Turtles (Terrapene mexicana triunguis) at Two Sites in Missouri.

Once ubiquitous, North American box turtles are experiencing reductions in abundance and range, but the magnitude of these losses is largely unknown. In Missouri, native box turtles (Terrapene mexicana triunguis and Terrapene ornata ornata) are declining across the state due to anthropogenic disturbances such as urbanization, habitat fragmentation, and vehicle collisions. Through radio-tracking over a period of 7 years, we documented the survival of adult three-toed box turtles at two sites in Missouri: Forest Park (urban park) and Tyson Research Center (TRC) (a protected rural forest). Estimated annual survival of adult turtles in Forest Park was 79% (95% CI: 0.68–0.87) while at TRC annual survival was 93% (95% CI: 0.83–0.97). The odds of annual survival for a turtle at TRC were 3.5 times that of a turtle living in Forest Park. “Winter kill,” which refers to box turtles found dead on the surface during brumation or within 2 weeks of emergence, was the most frequently documented category of mortality in Forest Park. At TRC, winter kill was not documented; however, the reasons for most deaths were unknown. These data raise questions about the potential of large urban parks as refuges for box turtles, which we may answer by future studies that compare box turtles living in multiple urban and rural settings. Our preliminary data suggest that even the largest urban parks may not be able to sustain populations of box turtles which has severe implications as urbanization continues to degrade and eliminate box turtle habitat throughout their range.

Cold-related Florida manatee mortality in relation to air and water temperatures.

Many tropical and subtropical species are sensitive to sudden temperature changes, especially drops in temperature. During winters 2009–2010 and 2010–2011, unusually cold temperatures occurred in many parts of Florida, USA, resulting in increased mortality of Florida manatees, sea turtles, fish, corals, and other species. The Florida manatee, in particular, is highly susceptible to cold stress and death when water temperatures drop below 20°C. We sought to characterize the magnitude and timing of reports of cold-related manatee carcasses in relation to fluctuations in water and air temperatures in central-east and central-west Florida during the six winters from 2008 to 2014. We used a generalized linear model to predict counts of manatee carcasses with a cold-related cause of death reported over 7-day bins in relation to various short-term (two weeks or less) and cumulative (incrementally summed from the start of the winter) heating-degree-day effects (HDD; < 20°C) and a categorical winter variable. Using water temperature data, the top-ranked model in both regions included a short-term temperature effect (14-day HDD sum) that preceded increases in reports of cold-related manatee carcasses by 7 days. Cumulative exposure to cold weather over the winter amplified effects on mortality in the central-east region. Quantifying the relationship between cold events and manatee mortality helps us prepare for rescue and salvage operations when extremely cold weather is forecast. This is especially important because anticipated loss or degradation of warm-water refuges due to human activities and sea level rise could potentially impact the manatee population in the future. These methods could also be applied to other species susceptible to cold-related mortality.

Decades of Road Mortality Cause Severe Decline in a Common Snapping Turtle (Chelydra serpentina) Population from an Urbanized Wetland

Road networks threaten biodiversity and particularly herpetofauna, including common snapping turtles (Chelydra serpentina), which have an especially slow life history that prevents rapid recovery of populations subjected to road mortality. Cootes Drive is a 2.5-km 4-lane highway that bisects wetland habitat used for nesting and overwintering by snapping turtles. We hypothesized that turtle mortality from collisions with vehicles on Cootes Drive has caused a male bias and a decline in the population as turtles attempt to access habitat on both sides of the road. Capture–mark–recapture studies confirmed a dramatic decline in the turtle population from 941 individuals in 1985 to 177 individuals in 2002, a loss of 764 individuals in only 17 yrs. Using the same data, we also determined that the population has been significantly male-biased since 1985. Using 2009–2016 road mortality data obtained from the Dundas Turtle Watch (a citizen-science program), we completed a population viability analysis using the 2002 population size estimate to isolate the impact of road mortality. We found that this population is at risk of extirpation due to road mortality. The population range overlapped with the Cootes Drive and 7 of the 10 tracked turtles had individual home ranges that overlapped with the road. Our findings support the hypothesis that road mortality has contributed to the dramatic decline in the snapping turtle population in Cootes Paradise Marsh. This population is in jeopardy of extirpation; therefore, exclusion fencing must be installed for an extended distance along both sides of surrounding roads to prevent turtles from crossing the road and to promote their use of existing aquatic culverts.

Caryospora-Like Coccidia Infecting Green Turtles (Chelonia mydas): An Emerging Disease With Evidence of Interoceanic Dissemination.

Protozoa morphologically consistent with Caryospora sp. are one of the few pathogens associated with episodic mass mortality events involving free-ranging sea turtles. Parasitism of green turtles (Chelonia mydas) by these coccidia and associated mortality was first reported in maricultured turtles in the Caribbean during the 1970s. Years later, epizootics affecting wild green turtles in Australia occurred in 1991 and 2014. The first clinical cases of Caryospora-like infections reported elsewhere in free-ranging turtles were from the southeastern US in 2012. Following these initial individual cases in this region, we documented an epizootic and mass mortality of green turtles along the Atlantic coast of southern Florida from November 2014 through April 2015 and continued to detect additional, sporadic cases in the southeastern US in subsequent years. No cases of coccidial disease were recorded in the southeastern US prior to 2012 despite clinical evaluation and necropsy of stranded sea turtles in this region since the 1980s, suggesting that the frequency of clinical coccidiosis has increased here. Moreover, we also recorded the first stranding associated with infection by a Caryospora-like organism in Hawai'i in 2018. To further characterize the coccidia, we sequenced part of the 18S ribosomal and mitochondrial cytochrome oxidase I genes of coccidia collected from 62 green turtles found in the southeastern US and from one green turtle found in Hawai'i. We also sequenced the ribosomal internal transcribed spacer regions from selected cases and compared all results with those obtained from Caryospora-like coccidia collected from green turtles found in Australia. Eight distinct genotypes were represented in green turtles from the southeastern US. One genotype predominated and was identical to that of coccidia collected from the green turtle found in Hawai'i. We also found a coccidian genotype in green turtles from Florida and Australia with identical 18S and mitochondrial sequences, and only slight inter-regional differences in the internal transcribed spacer 2. We found no evidence of geographical structuring based on phylogenetic analysis. Low genetic variability among the coccidia found in green turtle populations with minimal natural connectivity suggests recent interoceanic dissemination of these parasites, which could pose a risk to sea turtle populations.

Road mortality of freshwater turtles in Palawan, Philippines

The impact of road mortality on freshwater turtle populations on a global scale could be significant enough to cause the extinction of sensitive species. Essential data on roadkill abundance, composition, spatial patterns, and temporal distribution is needed for crafting mitigation strategies. To provide such information, a survey was conducted along the highway section (67 km) connecting Aborlan and Puerto Princesa City in Palawan, Philippines. Collection of data was done four times a month from January 2010 to December 2015. A total of 127 road-killed turtles belonging to two species of the Geoemydidae family were recorded, 102 (80.3%) of which were classified as the Southeast Asian Box Turtle (Cuora amboinensis) and 25 (19.7%) were identified as the Asian Leaf Turtle (Cyclemys dentata). The increase in road traffic noticed during the survey period possibly caused the corresponding increase in the roadkill counts of C. amboinensis, which is a more common species. Concurrently, the decline in the road-kill counts of C. dentata may indicate a severe drop in the population of this less common species. Roadside habitat types, time of the day, and presence of water bodies are found to be important predictors of road-killed turtles. High densities of road-killed turtles clustered in short segments of the road which identified as hotspots. Effective mitigating measures to curve down the impact of road mortality on turtle populations must be implemented and focusing the conservation strategies along the hotspots is considered an efficient and practical option.

NEUROLOGIC AND COMPUTED TOMOGRAPHY FINDINGS IN SEA TURTLES WITH HISTORY OF TRAUMATIC INJURY.

Boat strikes have been widely documented as a major cause of anthropogenic trauma and mortality in sea turtles. Axial trauma in these species involves the head and/or carapace and may cause severe damage to the nervous and pulmonary systems. The aims of this study were to develop an updated protocol for neurologic examinations in sea turtles, to describe computed tomography (CT) findings in sea turtles with sustained trauma, and to associate CT findings with neurologic status in sea turtles with and without traumatic injury. Ten sea turtles were examined, six green (Chelonia mydas) and four loggerhead (Caretta caretta) turtles: seven underwent neurologic and CT examinations, two had CT examinations only, and one had a neurologic examination only. The updated neurologic examination protocol was considered useful in differentiating normal from abnormal neurologic status, however some of these tests remain unreliable in sea turtles. Sea turtles with no history of trauma were found to have normal carapace shape, vertebral column, and neurologic status. Sea turtles with history of traumatic injury (more than 10 years prior to examination) had findings dependent on trauma site. Those with head trauma had variable presentations dependent on location of injury; while those with carapace trauma had varying degrees of kyphosis, lordosis, and scoliosis of the carapace, vertebral fractures, and paraparesis. Kyphosis of the carapace was associated with vertebral fractures detected on CT; however, the severity of vertebral abnormalities was not associated with the severity of neurologic deficits. These findings suggest that a combination of neurologic and CT examination may be beneficial in determining clinical significance of carapace deformation and associated neurologic deficits in sea turtles with traumatic injury.

Clinical pathology and health reference values for loggerhead sea turtles (Caretta caretta) and olive ridley turtles (Lepidochelys olivacea) in the Gulf of Ulloa, Baja California Sur, Mexico

Anthropogenic impact and environmental threats can cause diseases to marine turtles and in severe cases death, contributing to population decline worldwide. The Gulf of Ulloa (GU) represents an important foraging habitat for loggerhead sea turtles and olive ridley turtles; it is also considered a highly productive area for fisheries and is known for the mortality of marine turtles, which has been associated to bycatch. However, there is little information in the area regarding the health status of marine turtles; thus, the aims of this study were to (1) assess the health of marine turtles via physical examination, (2) generate their vital signs, (3) determine their hematological values, and (4) describe blood cell characteristics and its relationship with functional damage which can affect the organism’s systems. Clinical examinations were performed; complete blood count, clinical biochemistry, and clinicopathological evaluations were made, and their relationships with the functioning of the organism’s systems were described. With the sequential integration of medical and clinicopathological analysis, 56 loggerhead sea turtles and 16 olive ridley turtles from the GU were diagnosed as healthy. These pathological analyses are essential to evaluate marine turtles’ health, as well as to evaluate the health status of free-ranging populations, and have important applications for treatment and rehabilitation of sick and injured marine turtles. The baseline generated in this research provides information that can be taken as a reference for future research and used to generate management plans and conservation strategies for the organisms and for the ecosystem, together with the authorities.

Characterizing watercraft‐related mortality of sea turtles in Florida

ABSTRACTMortality from being struck by a motorized watercraft is considerable for many aquatic vertebrates around the world, including sea turtles. We studied stranded (i.e., dead, sick, or injured) sea turtles found in Florida, USA, during 1986–2014 and identified those with sharp force or blunt force injuries indicative of a vessel strike. About a third of stranded loggerheads (Caretta caretta), green turtles (Chelonia mydas), and leatherbacks (Dermochelys coriacea) had a vessel‐strike injury (VSI). The frequency of this injury was lower but still substantial for stranded Kemp's ridleys (Lepidochelys kempii; 26.1%) and hawksbills (Eretmochelys imbricata; 14.8%). Over the study period, the annual number of stranded loggerheads, green turtles, and Kemp's ridleys with a VSI increased as did the annual number of vessels registered in Florida. Eighty‐one percent of the stranded turtles with a VSI were found in the southern half of Florida and 66% of those were found along the southeast coast. By coastal county, the proportion of stranded sea turtles with a VSI was positively related to the mean annual number of registered vessels. The percentage occurrence of a VSI was highest for adult loggerheads, green turtles, and leatherbacks, and reproductively active individuals appeared to be particularly vulnerable to these injuries. We conducted necropsies on 194 stranded sea turtles with a VSI and concluded that this injury was the cause of death or the probable cause of death in ≥92.8% of these cases. During 2000–2014, we estimate that the mean annual numbers of stranded sea turtles that died from a VSI were 142–229 loggerheads, 101–162 green turtles, 16–32 Kemp's ridleys, 4–6 leatherbacks, and 2–4 hawksbills. Considering that only about 10–20% of sea turtles that died likely washed ashore, the overall annual mortality may have been 5–10 times greater than that represented by strandings. Most of the significant clusters of stranded sea turtles with a VSI occurred at inlets or passes and the probability that a stranded sea turtle had a VSI decreased with increasing distance from inlets or passes, navigable waterways, and marinas. We suggest focusing initial management efforts on reducing watercraft‐related mortality for all sea turtle species around 8 inlets in southeast Florida, reproductively active loggerheads and green turtles along the coast of southeast Florida, and Kemp's ridleys and adult male loggerheads at passes along the coast of southwest Florida. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society

Revisiting the hypothesis of sex-biased turtle road mortality

Road mortality poses a major threat to turtle populations. Several studies have suggested that the terrestrial movements associated with nesting increase this risk for females. The Ontario Turtle Conservation Centre (OTCC) is home to the Kawartha Turtle Trauma Centre, which admits 900 or more turtles a year, with road injuries the primary cause of admission. We tested the hypothesis that road mortality in turtles is female-biased using data from injured Midland Painted Turtles (Chrysemys picta marginata), Snapping Turtles (Chelydra serpentina), Blanding’s Turtles (Emydoidea blandingii), and Northern Map Turtles (Graptemys geographica) collected over about 126 000 km2 and admitted to OTCC’s hospital from January 2013 to October 2017. There was no difference in the number of male and female admissions of Midland Painted, Blanding’s, or Snapping Turtles (P &gt; 0.05); however, more female Northern Map Turtles than males were admitted (P &lt; 0.001). Admission of female turtles peaked in June during the nesting season, but male admissions were more evenly distributed throughout the season. Our admissions data provide a temporally unbiased and geographically broad snapshot of turtle–vehicle interactions that can directly inform conservation and management policies. Although our data are not equivalent to mortality rates, these results demonstrate that vehicle strikes can have a substantial impact on both female and male turtles.

A Unique Barrier Wall and Underpass to Reduce Road Mortality of Three Freshwater Turtle Species

Road mortality has become a primary threat to turtle populations. A variety of strategies have been applied to reduce turtle mortality; however, the effectiveness of these solutions remains largely untested. The few tests that have been conducted have often found the mitigation actions to be ineffective or prohibitively expensive for implementation at a landscape level. Thus, there is a need for inexpensive, effective, and rigorously tested methods for reducing turtle mortality on roads. Here, we investigate the potential efficacy of an inexpensive mitigation strategy, consisting of a barrier wall fabricated from High Density Polyethylene (HDPE) half-pipe, partnered with a pre-existing semiaquatic HDPE culvert as an ecopassage. We used survey data and a Before-After-Control-Impact (BACI) experimental design to assess the effectiveness of the mitigation and quantified the use of the ecopassage at the impact site after the barrier wall was installed. We found a significant interaction between the treatment effect and time period, with the impact site (but not control sites) showing significantly lower turtle counts after mitigation. The barrier wall reduced the number of turtles accessing the road by 94%, and there was no evidence of turtles circumnavigating the barrier. Turtles used the pre-existing culvert to pass under the road. We conclude that HDPE half-pipe partnered with an existing semiaquatic HDPE culvert can reduce road access by, and road mortality of, turtles. The use of standard road construction materials for barrier walls and underpasses results in a cost-effective design scalable to a landscape level.

Assessing Karenia brevis red tide as a mortality factor of sea turtles in Florida, USA.

Data on Karenia brevis red tides (≥105 cells l-1) and on dead or debilitated (i.e. stranded) Kemp's ridleys Lepidochelys kempii, loggerheads Caretta caretta, green turtles Chelonia mydas, hawksbills Eretmochelys imbricata, and leatherbacks Dermochelys coriacea documented in Florida during 1986-2013 were evaluated to assess red tides as a sea turtle mortality factor. Unusually large numbers of stranded sea turtles were found coincident with red tides primarily along Florida's Gulf coast but also along a portion of Florida's Atlantic coast. These strandings were mainly adult and large immature loggerheads and Kemp's ridleys, and small immature green turtles and hawksbills. Unusually large numbers of stranded leatherbacks never coincided with red tide. For the 3 most common species, results of stranding data modeling, and of investigations that included determining brevetoxin concentrations in samples collected from stranded turtles, all indicated that red tides were associated with greater and more frequent increases in the numbers of stranded loggerheads and Kemp's ridleys than in the number of stranded green turtles. The mean annual number of stranded sea turtles attributed to K. brevis red tide was 80 (SE = 21.6, range = 2-338). Considering typical stranding probabilities, the overall mortality was probably 5-10 times greater. Red tide accounted for a substantial portion of all stranded loggerheads (7.1%) and Kemp's ridleys (17.7%), and a smaller portion of all stranded green turtles (1.6%). Even though K. brevis red tides occur naturally, the mortality they cause needs to be considered when managing these threatened and endangered species.

Fishery strategy affects the loggerhead sea turtle mortality trend due to the longline bycatch

The western Mediterranean Sea is an important fishing ground for the Spanish surface longline fleet targeting swordfish, bluefin tuna, and albacore. Spanish Mediterranean waters, including contiguous international waters, are important feeding areas for thousands of juvenile and sub-adult loggerhead turtles. Due to the spatial overlap in fishing grounds between different longline métiers and loggerhead distribution, in the early 2000s, an estimated minimum of 60,000 loggerhead sea turtles were caught as bycatch in Mediterranean longline fisheries, including all countries operating in the area. The Spanish surface longline fleet is continually introducing technological and strategic innovations to improve the economic benefits of the fishery. These innovations lead to high variability in fishing gear and operational strategies from year to year.During the study period, there was a change in the specific contribution of each métier to total effort. Thus, since 2000 to the present, the Spanish traditional home-base surface longline targeting swordfish has been gradually modified or in other cases replaced by other métiers, and in most vessels it has been replaced by a new deeper semipelagic longline targeting the same species; which has led to a dramatic decrease in sea turtle mortality. The main result of this study is that loggerhead turtle post-release mortality due to the bycatch by the Spanish surface fleets using different longline métiers has significantly decreased during the last 8 years of the study period. We estimate an average post-release mortality around 1800 loggerheads sea turtles per year. The observed decrease in turtle mortality was an indirect effect of the introduction of changes in technology and fishing strategies in the fleets in the attempt to improve their economic objectives.

First-order effects of fire and prolonged-drought effects on an undescribed semi-aquatic turtle in Atlantic rainforest in southeastern Brazil

Fire usually impose considerable impacts on fauna, including loss of habitats and microhabitats, emigrations, injuries, or death. The general arquitecture of the local environment may play an important role in the extent that fire may act and the resulting burning effects. Understanding the exact extent of the effects of fire on vertebrate populations in natural environments is usually limited by the lack of information on the number of individuals dying during the event. Semi-aquatic turtles which usually move slowly on land, may suffer serious direct effects of fire. The mortality of turtles caused by fire and drought is well documented in the northern hemisphere, but few data are available from Brazil. Here we documented the death of individuals of a semi-aquatic still undescribed turtle species, Rhinoclemmys sp. n. on a coastal plain environment in southeastern Brazil, as result of a fire and a prolonged drought. Our results indicated that fire and drought contributed to the mortality of Rhinoclemmys sp. n. in the study area.