Fisher choice may increase prevalence of green turtle fibropapillomatosis disease

Abstract

Disease in wildlife populations is often controlled through culling. But when healthy individuals are removed and diseased individuals are left in the population, it is anticipated that prevalence of disease increases. Although this scenario is presumably common in exploited populations where infected individuals are less marketable, it is not widely reported in the literature. We describe this scenario in a marine turtle fishery in the Turks and Caicos Islands (TCI), where green turtles are harvested for local consumption. During a 2-year period, we recorded the occurrence of fibropapillomatosis (FP) disease in green turtles (Chelonia mydas) captured during in-water surveys and compared it with that of turtles landed in the fishery. 13.4% (n = 32) of turtles captured during in-water surveys showed externally visible signs of FP. FP occurred at specific geographic locations where fishing also occurred. Despite the disease being prevalent in the size classes selected by fishers, FP was not present in any animals landed by the fishery (n = 162). The majority (61%) of fishers interviewed expressed that they had caught turtles with FP. Yet, 82% of those that had caught turtles with the disease chose to return their catch to the sea, thereby selectively harvesting healthy turtles and leaving those with the disease in the population. Our study illustrates that fisher choice may increase the prevalence of FP disease and highlights the importance of this widely neglected driver in the disease dynamics of exploited wildlife populations.

Taxonomic distinctness in the diet of two sympatric marine turtle species

“…Sixteen survey sites were selected to represent turtle fishing sites, based on the information acquired during fisher interviews, and turtle capture‐mark‐recapture sampling sites (authors’ unpublished data and Stringell et al . ; Fig. ).…”

“…Turtle capture location was estimated following fisher interviews (authors’ unpublished data and Stringell et al . ). The size of juvenile to adult‐sized turtles (n = 91 green turtles, n = 45 hawksbill turtles) was measured along the midpoint of the carapace [curved carapace length from notch to tip (CCL) in cm: Bolten ].…”

Fibropapillomatosis prevalence and distribution in green turtles Chelonia mydas in Texas (USA)

“…Prevalence of FP ranged from 4.5 to 7.8% among different areas for turtles netted in the Key West National Wildlife Refuge (Florida, USA) from 2003 to 2012 (Herren et al 2018), though it remains as high as 70% for some lagoons on Florida's Atlantic coast (Ehrhart et al 2016). FP was present in 13.4% of netted green turtles in the Turks and Caicos Islands, West Indies (Stringell et al 2015). Additionally, prevalence of FP fluctuated from 0 to 75% in netted green turtles at 2 foraging sites in Puerto Rico from 1997 to 2014, with complete regression of visible tumors in individuals occurring within 2.7 yr on average (Patrício et al 2016).…”

Gross examination and Histopathology of Fibropapillomas in Chelonia mydas and Lepidochelys olivacea from Baja California Sur, Mexico

“…FP has a higher prevalence in near-shore habitats with poor water exchange (lagoons, bays, etc.) like LOL, and in areas that are impacted by human activities and urban development, suggesting that environmental degradation may play a significant role in the disease expression [43][44][45]. Consequently, the incidence of FP in sea turtles may prove to be a prime indicator of ecosystem health [46].…”