Welfare outcomes in a catch and release fishery: a case study of Atlantic Bluefin Tuna (Thunnus thynnus) in English waters

Many sports or recreational fisheries include catch and release elements. Whilst this limits mortality, there is relatively little evidence on ‘hook-to-release’ fishing practices and their potential wider impact. Here, we document the fishing practices in a limited, controlled trolling fishery for Atlantic bluefin tuna (BFT) in the South West of England between 2021 and 2023 (totalling 1655 fishing day-trips). Fishers taking part were educated each year in capture, handling, data-collection and tagging techniques. Practices at sea and data were self-reported and validated by direct observation and on-board camera systems. In total, more than 3300 BFT with a mean straight fork length of 177 cm (range: 95 cm to 288 cm) were captured, and only 23 at vessel mortalities (0.7%) were reported. Fight times varied between 3 min to 135 min (mean: 21 min), and showed a positive relationship with BFT weight. Injuries were rare (126 of 3267 observations, 3.9% overall) and were typically minor (87, 2.7%). Alertness at capture was occasionally reduced (79 of 3273 observations, 2.4% overall), and was more likely be observed after longer fight times. However, 36 (46%) of lethargic BFT reverted to full alertness after being towed at the side of the vessel for a short period of recovery. Fishers reported that training in fishing techniques and fish handling had a positive impact on their fishing activities. Overall, the data suggest that high welfare standards can be achieved in a recreational fishery and the combination of co-designed protocols, training and experience are associated with this outcome.