Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Fahlman, Andreas; Crespo-Picazo, José Luís; Sterba-Boatwright, Blair; Stacy, Brian A.; García-Párraga, Daniel

doi:10.1038/s41598-017-02819-5

Cited by 31 publications

(48 citation statements)

References 21 publications

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“…Sea turtles are suspectible to decompression sickness and gas embolism when retrieved quickly from depths >10 m, with an increased likelihood of delayed mortality from this condition (Fahlman et al, ; García‐Párraga et al, ). The occurrence of these conditions in the incidentally captured turtles was not assessed, nor were the released turtles followed, to check on delayed mortality.…”

Section: Discussionmentioning

confidence: 99%

“…In this study, all tows with incidentally captured turtles occurred at depths >10 m and 17.91% occurred at depths >80 m, raising the possibility that some turtles may have experienced decompression sickness and/or gas embolism, with delayed mortality after being released alive from the trawls. Future studies on this issue are needed for a more accurate estimate of sea turtle mortality rates in bottom trawling as well as to plan efforts to avoid or minimize the harmful effects of bycatch (Fahlman et al, ).…”

Section: Discussionmentioning

confidence: 99%

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

Tagliolatto

Giffoni²,

Guimarães

et al. 2019

Aquatic Conservation

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

Tagliolatto

Giffoni²,

Guimarães

et al. 2019

Aquatic Conservation

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“…ventilation-perfusion ratio in the lung, they may avoid DCS, while retaining the ability to manage pulmonary O 2 stores and CO 2 levels during dives (Fahlman et al, 2018;García-Párraga et al, 2018). Failure of this mechanism, caused by fisheries interaction, may explain the high incidence of GE during enforced submersion of turtles (Fahlman et al, 2017a;García-Párraga et al, 2014). We show that the PEPA, IPA and PASp contract when exposed to 5HT and ACh, which is qualitatively similar to the pulmonary artery in humans and other mammals (Cortijo et al, 1997;Furchgott and Bhadrakom, 1953;Van Nueten et al, 1985), and in line with previous studies with turtles and other reptiles (Berger, 1971;Burggren, 1977;Milsom et al, 1977;Taylor et al, 2009;Wang, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…However, if perfusion of the lung is maintained during certain times at depths shallower than the faveolar collapse depth, the decreasing ventilation-perfusion ratio would increase N 2 uptake, which in turn would increase the risk of GE after surfacing. Once venous bubbles form, a R-L shunt would pass bubbles directly to the systemic circulation without the ability for the lung to act as a filter (Bove, 1998;Cross and Jennings, 1994), increasing risk for GE to enter the systemic circulation (Fahlman et al, 2017a;García-Párraga et al, 2014;Vann et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…These observations are significant for sea turtle conservation as fishery bycatch is recognized as the greatest threat for most sea turtles worldwide (Lewison et al, 2013;Wallace et al, 2011). Additionally, considering that DCS probably contributes to postrelease mortality, undetected cases following release from the fishing gears may lead to significant underestimates of the numbers of turtles killed by fisheries (Fahlman et al, 2017a;García-Párraga et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Deciphering function of the pulmonary arterial sphincters in loggerhead sea turtles (Caretta caretta)

García-Párraga

Lorenzo

Wang

et al. 2018

Journal of Experimental Biology

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To provide new insight into the pathophysiological mechanisms underlying gas emboli (GE) in bycaught loggerhead sea turtles (Caretta caretta), we investigated the vasoactive characteristics of the pulmonary and systemic arteries, and the lung parenchyma (LP). Tissues were opportunistically excised from recently dead animals for in vitro studies of vasoactive responses to four different neurotransmitters: acetylcholine (ACh; parasympathetic), serotonin (5HT), adrenaline (Adr; sympathetic) and histamine. The significant amount of smooth muscle in the LP contracted in response to ACh, Adr and histamine. The intrapulmonary and systemic arteries contracted under both parasympathetic and sympathetic stimulation and when exposed to 5HT. However, proximal extrapulmonary arterial (PEPA) sections contracted in response to ACh and 5HT, whereas Adr caused relaxation. In sea turtles, the relaxation in the pulmonary artery was particularly pronounced at the level of the pulmonary artery sphincter (PASp), where the vessel wall was highly muscular. For comparison, we also studied tissue response in freshwater sliders turtles (Trachemys scripta elegans). Both PEPA and LP from freshwater sliders contracted in response to 5HT, ACh and also Adr. We propose that in sea turtles, the dive response (parasympathetic tone) constricts the PEPA, LP and PASp, causing a pulmonary shunt and limiting gas uptake at depth, which reduces the risk of GE during long and deep dives. Elevated sympathetic tone caused by forced submersion during entanglement with fishing gear increases the pulmonary blood flow causing an increase in N 2 uptake, potentially leading to the formation of blood and tissue GE at the surface. These findings provide potential physiological and anatomical explanations on how these animals have evolved a cardiac shunt pattern that regulates gas exchange during deep and prolonged diving.

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Life Aquatic: A Review of Adaptations in Non‐Avian Reptiles

Carrillo¹,

Cruz²,

Kong³

et al. 2022

Encyclopedia of Life Sciences

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Nonavian reptiles are among the many tetrapod lineages that have secondarily evolved semi‐aquatic and fully aquatic lifestyles. As thermal conformers occupying varying depths of the marine and freshwater environment, reptiles are great models for studying aquatic adaptations. The approximately 600 crocodilians, turtles, lizards and snakes enter the water for numerous reasons including to forage, mate, lay eggs and give live birth, seasonally hibernate and seek refuge from predators. Those that feed in the aquatic environment can be separated into two categories, obligate and facultative foragers, that contribute to different degrees of aquatic dependence. Morphological traits such as protruding nostrils and tentacles or chin barbels have evolved repeatedly in aquatic lineages. Aquatic nonavian reptiles must also overcome challenges associated with submersion similar to endotherms, including voluntary apnea, hydrostatic pressure at depth, and thermo‐ and osmoregulation. Some notable morphological, behavioural and physiological adaptations that facilitate movement through the water or prolonged submergence times include streamlined morphology, cutaneous respiration and depressed metabolic rates. Key Concepts Nonavian reptiles that forage for prey in the water are either facultative foragers or obligate foragers. In terms of aquatic representation, all crocodilians are semi‐aquatic, with turtles having the next largest proportion of aquatic individuals, followed by snakes and lizards, despite snakes being the only group with fully aquatic species. There are a myriad of behavioural, morphological and physiological adaptations observed in aquatic nonavian reptiles that are taxon‐specific but also others that are convergent across disparate groups. Despite the striking differences in body shapes between nonavian reptiles, aquatic members of all groups have modified their bodies to take on more streamlined shapes. Valved or protruding nostrils and piscivorous feeding habits are commonly observed across all aquatic nonavian reptile clades. Many marine inhabitants have the ability to osmoregulate and get rid of excess salt. Nonavian reptiles are great models for studying aquatic adaptations as they perform a combination of behaviours in the water including foraging, mating and seasonal hibernation despite homeostatic challenges pertaining to the aquatic environment.

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Defining risk variables causing gas embolism in loggerhead sea turtles (Caretta caretta) caught in trawls and gillnets

Cited by 31 publications

References 21 publications

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

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

Deciphering function of the pulmonary arterial sphincters in loggerhead sea turtles (Caretta caretta)

Life Aquatic: A Review of Adaptations in Non‐Avian Reptiles

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