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Authors
Abstract(s)
Stress levels in neonate and juvenile sharks can influence the health and survival of the individual, as
well as the overall population resilience. This thesis explores interspecific differences in health and
stress indicators in juvenile sharks caught in Sal Rei Bay (SRB), a multi-specific shark nursery area in
Boa Vista Island, Cabo Verde. Body condition, capture resilience, and a range of biochemical
parameters (cholesterol, glucose, phosphate, creatine, alanine aminotransferase, alkaline phosphatase,
potassium, total protein) were assessed in four shark species frequenting SRB — milk shark
(Rhizoprionodon acutus), blacktip shark (Carcharhinus limbatus), scalloped hammerhead shark
(Sphyrna lewini), and Atlantic weasel shark (Paragaleus pectoralis) — caught using artisanal fishing
methods traditionally employed in the region (gillnets and angling). Recuperation scores varied among
species and generally indicated faster recovery in individuals captured by angling compared to gillnets.
Milk sharks, however, tended to recover quicker after gillnet capture. Hammerhead sharks showed the
overall slowest recovery. Significant species-specific differences were revealed in nearly all analysed
indicators, with a frequent influence of the umbilical scar. A significant influence of gear type was only
detected for the two biomarkers alanine aminotransferase and alkaline phosphatase. The present results
showcase the influence of species, development, and fishing-method on physiological indicators in
juvenile sharks in SRB, discussing how species-specific ecological and behavioural characteristics
might have influenced the results obtained. The influence of environmental and other anthropogenic
pressures should be considered more thoroughly in future studies. By yielding the first fundamental
insights into the interspecific differences in stress levels among juvenile sharks in the SRB nursery area,
the present dissertation contributes to the design of future and ongoing monitoring efforts. Further, it
enhances the comprehension of local interactions between sharks and the local artisanal fishery,
addressing a knowledge gap for formulating effective, locally-tailored conservation strategies.
Description
Tese de mestrado, Ecologia Marinha, 2025, Universidade de Lisboa, Faculdade de Ciências
Keywords
Recuperação da captura stress fisiológico comparação interespecífica conservação de tubarões pressão pesqueira Teses de mestrado - 2025