Loggerhead turtles killed by vessel and fishery interaction in Virginia, USA, are healthy prior to death

Abstract

Human-induced mortality of marine animals is a complex issue and the health of animals prior to human interaction is often questioned. We reviewed 74 cases of loggerhead turtles in the mid-Atlantic region of the US to determine whether fresh, dead loggerhead turtles that died from acute vessel or fishery interaction (acute VI/FI) were healthy animals prior to human-induced mortality. We used the presence of significant underlying pathology to determine health status and compared the body condition and adipose stores with turtles that died from other causes. We qualitatively and quantitatively assessed body condition using images, morphometrics, mass dissection data, % lipid and % triacylglycerol in the adipose tissue. We used the quantitative indices to validate the qualitative index. Acute VI/FI turtles were significantly less likely to have significant lesions indicating compromised health compared with turtles that died from other causes (χ 2 = 12.9012, df = 1, p = 0.0003). There was a significant relationship between qualitative body condition and cause of death category, with acute VI/FI turtles more likely to exhibit normal body condition than turtles that died from other causes (χ 2 = 18.879, df = 2, p < 0.0001). Values for 3 quantitative indices were significantly higher for acute VI/FI turtles compared with other causes of death, while 3 others were not different across turtles, most likely because there were some healthy turtles in the 'other' cause of death category. Our results suggest that the majority of acute VI/FI loggerhead turtles represented normal, healthy turtles in the population and were not compromised prior to human-induced mortality.

Survey on the presence of non–dioxine‐like PCBs (NDL‐PCBs) in loggerhead turtles (Caretta caretta) stranded in south Mediterranean coasts (Sicily, Southern Italy)

“…All the loggerhead turtles examined were in good body condition; this was also confirmed by modified Fulton's K values. Barco et al found a positive correlation between modified Fulton's K values and the adipose mass index, giving reasons for the significantly higher PCB levels in adipose tissue than in muscle tissue found in the present study.…”

“…All loggerhead sea turtles examined belonged to the thin and normal classes, according to Heithaus et al [22] and Barco et al [23], with a convex underside and substantial fat reserves near the neck.…”

“…We were able to assign a body condition class to the recovered loggerhead turtles based on external characteristics, according to the method of Heithaus et al . A modified Fulton's K index was calculated for each loggerhead sea turtle, considering length, width, and depth of the carapace . Examination of the stomach contents revealed the presence of plastic shopping bag residues in 10 specimens.…”

Distribution and toxicity of persistent organic pollutants and methoxylated polybrominated diphenylethers in different tissues of the green turtle Chelonia mydas

“…At the same time, it may also reflect the animals' health condition, a different lipid composition or the complexity behind the distribution and fate of pollutants in the body of a species for which metabolic capacities and toxicokinetics in general are poorly known. Barco et al (2016) observed that the amount of lipids in fat tissue differed between turtles who died either from fishing incidents or other causes, indicating that those who died through the former cause were in better condition with higher lipid amounts. In the present study, the causes of death could not be identified for all individuals, however, the majority of individuals had infections, serious flesh wounds or considerable quantities of plastic debris in their stomachs.…”

Plastic Pollution and Small Juvenile Marine Turtles: A Potential Evolutionary Trap

“…Furthermore, working with stranded animals has been suggested to lead to biases (Casale et al, 2016). Surveying plastics in animals that die from fisheries interactions, however, might be more likely to exhibit normal healthy body condition than those that die of other causes (Barco et al, 2016;Casale et al, 2016). Consequently, longline bycaught turtles used in this study provide a unique data source to assess the plastic burden in what may be relatively healthy individuals.…”