Causes of Stranding and Mortality, and Final Disposition of Loggerhead Sea Turtles (Caretta caretta) Admitted to a Wildlife Rehabilitation Center in Gran Canaria Island, Spain (1998-2014): A Long-Term Retrospective Study

Abstract

AimsThe aims of this study were to analyze the causes of stranding of 1,860 loggerhead turtles (Caretta caretta) admitted at the Tafira Wildlife Rehabilitation Center in Gran Canaria Island, Spain, from 1998 to 2014, and to analyze the outcomes of the rehabilitation process to allow meaningful auditing of its quality.MethodsPrimary causes of morbidity were classified into seven categories: entanglement in fishing gear and/or plastics, ingestion of hooks and monofilament lines, trauma, infectious disease, crude oil, other causes, and unknown/undetermined. Final dispositions were calculated as euthanasia (Er), unassisted mortality (Mr), and release (Rr) rates. Time to death (Td) for euthanized and dead turtles, and length of stay for released (Tr) turtles were evaluated.ResultsThe most frequent causes of morbidity were entanglement in fishing gear and/or plastics (50.81%), unknown/undetermined (20.37%), and ingestion of hooks (11.88%). The final disposition of the 1,634 loggerhead turtles admitted alive were: Er = 3.37%, Mr = 10.34%, and Rr = 86.29%. Er was significantly higher in the trauma category (18.67%) compared to the other causes of admission. The highest Mr was observed for turtles admitted due to trauma (30.67%). The highest Rr was observed in the crude oil (93.87%) and entanglement (92.38%) categories. The median Tr ranged from 12 days (unknown) to 70 days (trauma).ConclusionsThis survey is the first large-scale epidemiological study on causes of stranding and mortality of Eastern Atlantic loggerheads and demonstrates that at least 71.72% of turtles stranded due to anthropogenic causes. The high Rr (86.29%) emphasizes the importance of marine rehabilitation centers for conservation purposes. The stratified analysis by causes of admission of the three final disposition rates, and the parameters Td and Tr should be included in the outcome research of the rehabilitation process of sea turtles in order to allow comparative studies between marine rehabilitation centers around the world.

Estimating freshwater turtle mortality rates and population declines following hook ingestion

“…; Orós et al. ). Presumably, these animals would have higher survival rates than turtles that ingested hooks and were not captured.…”

“…), or as having ingested a hook (Orós et al. ). In studies where data were from a rehabilitation effort, we considered a euthanized turtle as an individual that died because of its wounds from interacting with a hook.…”

“…We used a similar approach to estimate mortality of a turtle that ingested a hook by incorporating data from multiple studies on mortality from hook ingestion in multiple species of turtles (Adimey et al 2014;Rivas et al 2014;Swimmer et al 2014;Orós et al 2016) (Supporting Information). For data from Adimey et al (2014), more than half of the turtles that interacted with fishing gear were hooked externally in a flipper.…”

“…Those individuals were removed from the data set because we were interested in mortality from individuals that ingested hooks. In the other studies from which we took data, turtles hooked in the mouth were categorized as deeply hooked (Swimmer et al 2014), as having an imbedded hook (Rivas et al 2014), or as having ingested a hook (Orós et al 2016). In studies where data were from a rehabilitation effort, we considered a euthanized turtle as an individual that died because of its wounds from interacting with a hook.…”

Foreign Body Ingestion and Treatment Methods in Sea Turtles

“…Turkiye Klinikleri J Vet Sci 2017;8(1-2): [1][2][3][4][5][6] malıdır. Barsaklar ve periton emilebilen iplikle, deri ise emilmeyen iplik ya da deri stapleri kullanılarak bilinen cerrahi kurallar doğrultusunda kapatılmalıdır.…”