Explanatory variables

Potential explanatory variables of discard survival can be categorized as either technical, environmental, or biological. Two approaches are suggested to identify relevant explanatory variables or stressors for a survival assessment: (i) conceptually tracing an organism’s pathway through capture, handled above the water surface, release overboard and eventually return to its habitat; and (ii) conduct a literature search of relevant material. Once relevant variables have been identified, the method of measurement, and the required degree of accuracy need to be considered. The rapid review presented here identified common potential explanatory variables of discard survival. As examples: • Technical: gear type and configuration, handling, deployment duration, • Environmental: water temperature, depth change, air exposure, • Biological: body size and physical injury. It is important to remember that intercorrelations may exist between potential explanatory variables, which are difficult to account for unless a rigorous, well-replicated design is conducted in a more controlled setting.