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Site fidelity is not revealed by genetic markers in stingrays

2020; Wiley; Volume: 96; Issue: 6 Linguagem: Inglês

10.1111/jfb.14377

1095-8649

Michel J. Kaiser,

Fish Ecology and Management Studies

The utility of conservation management tools, such as marine protected areas, is rarely based on an informed knowledge of the life-history characteristics of the species for which such conservation measures are intended (Stewart et al., 2009). Tanja Schwanck and colleagues (Schwanck et al., 2020) undertook an elegant study in which they combined 30 months of mark-recapture data with genetic techniques to understand patterns of movement and connectivity in a population of southern stingray (Hypanus americanus, Hildebrand & Schroeder, 1928). They tagged and sampled 200 sub-adult and adult stingrays from nine sites around Cape Eleuthera in The Bahamas. From this population, over one third were recaptured revealing that female fish appeared much more restricted in terms of their home range, compared to males. Despite this interesting finding, an examination of microsatellites at five loci and a mitochondrial marker revealed high degrees of genotypic variability as well as genetic exchange between Cape Eleuthera and three other sample sites in the central and western Bahamas, suggesting that gene flow is well maintained for this area by females and males alike. The study not only highlights the challenge to align relevant timescales regarding behavioural patterns inferred from contemporary tagging studies with genetic patterns which may evolve over timescales of millennia; it also emphasizes the difficulty in trying to understand the highly diverse behavioural patterns throughout the life-history of marine animals. Although the reported genetic diversity is good news for the southern stingray, the study showcases how difficult the design of effective and efficient management would be. For the purposes of conservation of southern stingrays, spatial management measures would seem appropriate to protect sub-adult and adult females, but might leave male and juvenile fish exposed to biased fishing pressure as these seem less site-attached to the habitats studied in the paper. This could lead to the potential for sex over-fishing as well as endangering vulnerable life-stages. The complexity of life-history characteristics in marine organisms needs to be taken into consideration when tailoring suitable conservation management, but requires extensive and interdisciplinary investigation. Consequently, it is crucial to adapt, develop and evaluate management measures continuously to integrate new knowledge and thereby maximise the protection of animals of conservation concern.