Reporting by-catch and mortalities in targeted biological field surveys on fishes
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1. There is a paucity of information on the mortality of fishes and the capture and mortality of non-target by-catch organisms during scientific fish research surveys. 2. To investigate the extent of by-catch and reporting by biologists during fish surveys, a questionnaire survey of active field biologists in southern Africa was undertaken together with two case studies of field surveys from nine river systems in southern Africa. 3. The majority of researchers questioned record non-target organisms only occasionally (40%), and very few collect additional biological information (15%) with some not recording any information at all (20%). The vast majority of researchers do not, however, present or publish by-catch or mortality data despite this information having been collected. The case studies using fish field surveys show that while by-catch is often low, non-fish vertebrates (amphibians, reptiles and mammals) and invertebrates such as large crustaceans are often present. Fish surveys also resulted in unwanted mortality of both target and by-catch organisms. 4. It is proposed that reporting by-catch during field surveys of fishes can provide important information on distribution, abundance and population structures of certain non-target fauna and that in addition to by-catch considerations, indirect mortality associated with gear use should also be reported and recorded. Such information will aid in the assessment of risk of deploying certain gear types in certain environments.
- RESEARCH: Weyl, O