Evaluating Bycatch: A National Approach to Standardized Bycatch Monitoring Programs Technical memo

摘要

Bycatch for the purposes of this report is defined as the discarded catch of any living marine resource plus unobserved mortality due to a direct encounter with fishing gear. This definition is based on the bycatch definition that appears in the 1998 National Marine Fisheries Service (NMFS) report Managing the Nation's Bycatch but it does not include retained incidental catch as a component of bycatch. However, NMFS is aware that for some species, such as protected species, the primary management concern is the level of incidental catch, not the disposition of that catch. To meet its stewardship responsibilities, NMFS is committed both to account for target catch, retained incidental catch and bycatch and to decrease each of these three sources of fishing morality as appropriate to prevent overfishing, to rebuild overfished stocks and in general to provide the greatest net benefits to the Nation over time from the fisheries. Bycatch occurs if a fishing method is not perfectly selective. A fishing method is perfectly selective if it results in the catch and retention only of the desired size, sex, quality, and quantity of the desired species without other fishing-related mortality. Very few fishing methods are perfectly selective and typically the discard survival rate is less than 100%; therefore, bycatch is a source of fishing mortality in most fisheries.