Browsing by Author "West, Katie Georgina Harriet"
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- Physiological effects of hooking in longline fisheries in Algarve and the welfare implications for fishPublication . West, Katie Georgina Harriet; Guerreiro, Pedro MiguelThis thesis investigates the physiological responses and welfare implications of teleost fish subjected to artisanal longline fisheries in the Algarve region. The study focuses on understanding how different post-capture treatments and varying soak times impact fish vitality and stress markers, including glucose, lactate, cortisol, and osmolality. Both on-vessel fieldwork and in-house experiments were conducted to assess the physiological stress responses of Sparus aurata and other sparid species such as Diplodus sargus, Diplodus vulgaris, and Pagellus erythrinus. The results revealed no significant species-specific differences in vitality decline, with all species showing a sharp decrease in vitality overtime. Changes in physiological parameters showed similar pattern for the three species, with increases in lactate and osmolality over time, reaching the highest values at 120 min after capture, while a general decline in glucose concentrations was observed. Cortisol was already elevated at capture and remained high throughout, increasing only in D. sargus. The in-house experiments demonstrated that neither post-capture treatment (Dry, Ice, Ice Slurry) nor soak duration (0, 30, 90 minutes) significantly influenced vitality loss, reinforcing that time was the primary driver. Physiological stress indicators showed significant increases in lactate and osmolality over time, with a sharp glucose spike under ice treatment and stable but variable cortisol levels between treatments. This study contributes to the growing body of research on fish welfare in wild-capture fisheries by applying a function-based welfare approach. The findings provide valuable insights into the physiological responses of fish post-capture and offer recommendations for improving fish handling practices in artisanal longlining, with the ultimate goal of minimising stress and enhancing fish welfare. The study underscores the importance of minimising exposure time post-capture to reduce physiological stress in the artisanal longline fishery of the Algarve.