Blood Biochemistry of Sea Turtles Captured in Gillnets in the Lower Cape Fear River, North Carolina, USA

Abstract

Mortality due to fisheries interactions has been implicated as a contributor to population decline for several species of sea turtle. The incidental capture of sea turtles in the coastal gillnet fisheries of North Carolina, USA, has received much attention in recent years, and mitigation measures to reduce sea turtle mortality due to gillnet entanglement are a high priority for managers and conservationists. Efforts to evaluate effects of gillnet entanglement on sea turtle populations are complicated by the lack of information on health status of turtles released alive from nets and postrelease mortality. We obtained blood samples from green (Chelonia mydas) and Kemp's ridley (Lepidochelys kempii) sea turtles captured in gillnets for 20–240 minutes to assess the impacts of gillnet entanglement on blood biochemistry and physiological status. We measured concentrations of lactate, corticosterone, ions (Na+, K+, Cl‐, P, Ca2+), enzymes (lactate dehydrogenase [LDH], creatine phosphokinase [CPK], aspartate aminotransferase [AST]), protein, and glucose in the blood and also performed physical examinations of turtles to document external indicators of health status (injuries, lethargy, muted reflexes). We evaluated the effects of entanglement time on blood biochemistry and to look for correlations between blood biochemistry and results of the physical examinations. We observed a significant increase in blood lactate, LDH, CPK, phosphorus, and glucose with increased entanglement time. Alterations in blood biochemistry were generally associated with a decline in health status as indicated by results of the physical examination. Although entanglement time plays an important role in determining the health status of sea turtles upon release from a gillnet, our results suggest that factors such as the depth and severity of entanglement may also have an effect on health status of turtles and the probability of postrelease survival. We were unable to set a maximum unattended gillnet soak time to minimize impacts on captured sea turtles, and therefore recommend that fisheries managers continue to enforce the net attendance regulations currently in place in the lower Cape Fear River, North Carolina, during the summer months.

Physiological disturbances and behavioural impairment associated with the incidental capture of freshwater turtles in a commercial fyke-net fishery

“…These findings agree with previous research suggesting that water temperature, regardless of the oxygen content, can limit duration of survival (Ultsch 1989). Similar studies have assessed the physiological effects of various types of fishing gear, such as trawl nets (Stabenau et al 1991, Harms et al 2003 and gillnets (Snoddy et al 2009) on blood physiology of marine turtles and have shown similar effects of entrapment on blood physiology as our study.…”

Biometria corporal e parâmetros hematológicos de Trachemys scripta elegans e Trachemys dorbignyi (Testudines: Emydidae) criadas em cativeiro em Petrolina, Pernambuco

“…Em tartarugas o estado de saúde pode ser avaliado através do hemograma (Pires et al 2006, Deem et al 2009), por isto os valores hematológicos têm sido investigados em tartarugas marinhas (Pires 2007, Casal et al 2009, Deem et al 2009, Pires et al 2009, Santos et al 2009, Snoddy et al 2009, Flint et al 2010) e de água doce (Brites 2002, Tesserolli 2004, Hidalgo-Vila et al 2007, Ferronato 2008, Silva 2011. Contudo, no gênero Trachemys os poucos estudos existentes limitam a discussão dos resultados (Alves 2013), pois fatores como alterações no habitat, introdução de espécies invasoras, poluição ambiental, uso insustentá-vel, mudança climática global (Gibbons et al 2000, Ruiz et al 2002, sexo, tamanho, idade e alimentação (Deem et al 2009); técnicas utilizadas, tempo da amostra, manejo do animal, esforço físico, estado nutricional, condição fisioló-gica e mental, sazonalidade e contenção química podem levar a grandes variações nos testes realizados por diferentes laboratórios (Hawkey & Dennet 1989).…”

Physiological ramifications for loggerhead turtles captured in pelagic longlines

“…for 5 min, and plasma was transferred to cryogenic tubes for storage at 2808C. Plasma corticosterone (CORT) levels were determined by radioimmunoassay [10]. Spectrophotometric techniques were used to analyse blood glucose and lactate [10].…”

“…Sea turtles may experience a variety of injuries as a result of gear interactions, and tissue damage owing to either hooking or landing may result in blood loss and a decrease in packed cell volume (PCV). Capture and restraint in fishing gear may trigger the systemic stress response, resulting in elevated levels of corticosterone and glucose [9,10]. Efforts to escape gear and reach the surface to breathe may result in metabolic disturbances, particularly an increase in blood lactate as turtles increase reliance on anaerobic metabolism [10][11][12][13].…”

“…Longline-captured and hand-captured loggerhead turtles exhibited similar blood lactate levels (range 3.9-11.6 mmol l ; table 1) [10]. Capture by trawl and gillnet often results in forced submergence, which necessitates increased reliance on anaerobic metabolism and, consequently, more pronounced increases in lactate [10,13].…”