This study aims to assess and summarize the principal factors affecting the stress, injury and mortality of fish that arise from fishing processes, particularly when fish escape from trawl gears. Potential sources of error in the assessment of survival are identified, and improved methodological approaches and practices are suggested. Furthermore, the study attempts to evaluate the key principles for designing fishing gears and operations that reduce or eliminate the mortality of escapees. Finally, it assesses the problems associated with estimating the impacts of unaccounted fish mortality.
The author is very grateful for the support and assistance provided by Dr Wilfried Thiele (FAO Fisheries Technology Service) in the preparation of this study. Gratitude is also extended to Mr Vesa Tschernij (Iconex Ltd, Finland) for helping to prepare the illustrations, which make the message of this report easier to understand. The author also acknowledges the critical review and useful comments of Dr Matt Broadhurst (Coffs Harbour, Australia), Dr Michael Davis (Newport, United States) and Dr Aud Vold Soldal (Bergen, Norway), and would like to express his warmest thanks to Dr Gabriella Bianchi (FAO Marine Resource Service), Dr Dan Erickson (Eugene, United States) and Dr Francesco Sardà (Barcelona, Spain), who provided invaluable advice and comments during the preparation of this report. All images are courtesy of the author.