Novel Use of a Shark Model to Elicit Innate Behavioral Responses in Sea Turtles: Application to Bycatch Reduction in Commercial Fisheries

Bostwick, Angela; Higgins, Benjamin M.; Landry, André M.; McCracken, Marti L.

doi:10.2744/ccb-1110.1

Cited by 12 publications

(5 citation statements)

References 32 publications

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“…Modifications to fishing equipment that better align risk and assessment in non-target animals have been introduced to minimize bycatch (Gilman, 2011), including introduction of risk cues alongside fishing equipment so that the gear is detected, perceived as risky, and avoided by bycatch species (Southwood et al, 2008;Jordan et al, 2013; Figure 3). Specific sensory tools include acoustic deterrents (Southwood et al, 2008;Waples et al, 2013) olfactory or electrosensory cues (Jordan et al, 2013), LED lights (Bielli et al, 2020), or predator decoys (Bostwick et al, 2014). For species that are not consistently excluded using bycatch reduction devices [e.g., smalleyed round stingray (Urotrygon microphthalmum); Willems et al, 2016], innovations in behavioral deterrents may be necessary to reduce capture.…”

Section: Reducing Bycatch In Fisheriesmentioning

confidence: 99%

Mismatch Between Risk and Response May Amplify Lethal and Non-lethal Effects of Humans on Wild Animal Populations

2021

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Human activity has rapidly transformed the planet, leading to declines of animal populations around the world through a range of direct and indirect pathways. Humans have strong numerical effects on wild animal populations, as highly efficient hunters and through unintentional impacts of human activity and development. Human disturbance also induces costly non-lethal effects by changing the behavior of risk-averse animals. Here, we suggest that the unique strength of these lethal and non-lethal effects is amplified by mismatches between the nature of risk associated with anthropogenic stimuli and the corresponding response by wild animals. We discuss the unique characteristics of cues associated with anthropogenic stimuli in the context of animal ecology and evolutionary history to explore why and when animals fail to appropriately (a) detect, (b) assess, and (c) respond to both benign and lethal stimuli. We then explore the costs of over-response to a benign stimulus (Type I error) and under-response to a lethal stimulus (Type II error), which can scale up to affect individual fitness and ultimately drive population dynamics and shape ecological interactions. Finally, we highlight avenues for future research and discuss conservation measures that can better align animal perception and response with risk to mitigate unintended consequences of human disturbance.

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Section: Reducing Bycatch In Fisheriesmentioning

confidence: 99%

Mismatch Between Risk and Response May Amplify Lethal and Non-lethal Effects of Humans on Wild Animal Populations

2021

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“…In effect, reliance upon the shell for protection as occurs in terrestrial and some aquatic chelonians is replaced by an alternative strategy that relies upon both behavior (vigilance, swimming speed, and maneuverability; Heithaus, Frid, & Dill, ) and morphology (the shell as a shield rather than a fortress) to thwart shark attacks on larger individuals. Those behavioral responses have been observed in both loggerheads and ridley turtles (Heithaus, ; Bostwick, Higgins, Landry, & McCracken, ). However, for small juveniles, such as those considered here, there are no effective defenses (except to avoid detection) against predators that take prey by biting; instead, armoring appears designed to limit the impact of smaller, gape‐limited predators (Salmon & Scholl, ).…”

Section: Discussionmentioning

confidence: 70%

The early ontogeny of carapace armoring in hawksbill sea turtles (Eretmochelys imbricata), with comparisons to its close relatives (Loggerhead, Caretta caretta; Kemp's ridley, Lepidochelys kempii)

Salmon

Coppenrath

Higgins

2018

Journal of Morphology

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In this study, we compare and contrast armoring strategies during early ontogeny among three related species of marine turtles: the hawksbill, a species that diverged about 29 mya from the loggerhead and Kemp's ridley, which diverged from one another about 16 mya. Our purpose was to determine whether there was a correlation between divergence time and the evolution of unique morphological armoring specializations among these species. To find out, we completed a more detailed analysis of shell morphology for all of the species that revealed the following patterns. First, each species has evolved a somewhat different armoring strategy, suggesting that shell morphological evolution is surprisingly flexible. Second, hawksbills possess armoring features that are unique among all marine turtle species, suggesting a correlation between divergence through time and divergence in morphology. However, hawksbills also frequent coral reefs and selection pressures promoting their survival in those habitats may also have shaped their unique morphology. In contrast, loggerhead and Kemp's ridley turtles share similar armoring features that differ primarily in when during ontogeny they appear and in their degree of expression. Third, the armoring adaptations shown generally by juvenile marine turtles resemble those found among marine fishes of comparable size, probably because both small turtles and fishes are exposed to similar predators that promote evolutionarily similar adaptations.

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“…A rapid increase in proportional body width should soon make the turtles too wide to swallow and, once the turtles grow larger, offer a broad surface that acts like a shield to prevent other predators, such as sharks, from biting effectively (Heithaus, ). This behavior was also observed and described as “defensive carapace turns” when laboratory reared loggerheads were first exposed to a realistic shark model (Bostwick et al, ). The extreme development of such a body shape, as seen in ridley turtles, may occur because as an adult, this species is the smallest marine turtle and thus may require a proportionally broader surface as an effective defense.…”

Section: Discussionmentioning

confidence: 93%

The ontogeny of morphological defenses in Kemp's ridley (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtles

Salmon

Higgins

Stewart

et al. 2015

Journal of Morphology

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Marine turtles are large reptiles that compensate for high juvenile mortality by producing hundreds of hatchlings during a long reproductive lifespan. Most hatchlings are taken by predators during their migration to, and while resident in, the open ocean. Their survival depends upon crypticity, minimizing movement to avoid detection, and foraging efficiently to grow to a size too difficult for predators to either handle or swallow. While these behavioral antipredator tactics are known, changes in morphology accompanying growth may also improve survival prospects. These have been only superficially described in the literature. Here, we compare the similarities and differences in presumed morphological defenses of growing loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) posthatchlings, related species that differ in growth rate, timing of habitat shift (the return from oceanic to neritic locations), and size at maturity. In both species, vertebral spination and carapace widening increase disproportionally as small turtles grow, but later in ontogeny, the spines regress, sooner in ridley than in loggerhead turtles. Carapace widening occurs in both species but loggerheads are always longer than they are wide whereas in Kemp's ridley turtles, the carapace becomes as wide as long. Our analysis indicates that these changes are unrelated to when each species shifts habitat but are related to turtle size. We hypothesize that the spines function in small turtles as an early defense against gape-limited predators, but changes in body shape function throughout ontogeny-initially to make small turtles too wide to swallow and later by presenting an almost flat and hardened surface that large predators (such as a sharks) are unable to grasp. The extremely wide carapace of the Kemp's ridley may compensate for its smaller adult size (and presumed greater vulnerability) than the loggerhead.

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Novel Use of a Shark Model to Elicit Innate Behavioral Responses in Sea Turtles: Application to Bycatch Reduction in Commercial Fisheries

Cited by 12 publications

References 32 publications

Mismatch Between Risk and Response May Amplify Lethal and Non-lethal Effects of Humans on Wild Animal Populations

Mismatch Between Risk and Response May Amplify Lethal and Non-lethal Effects of Humans on Wild Animal Populations

The early ontogeny of carapace armoring in hawksbill sea turtles (Eretmochelys imbricata), with comparisons to its close relatives (Loggerhead, Caretta caretta; Kemp's ridley, Lepidochelys kempii)

The ontogeny of morphological defenses in Kemp's ridley (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtles

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