Decreasing Uncertainty; Combining Observer and Industry-Reported Discards

Discarded catch can be an important source of fishing mortality on certain stocks. Uncertainty in the estimates of discarded catch complicates the quantification of fishery removals in stock assessments and the management of fishery quotas. Observer data, which has been available in the Northeast United States since 1989, has allowed for the estimation of fishery discards with varying levels of precision.  Observers trained by the Northeast Fisheries Observer Program (NEFOP) provide good estimates on the types and quantity of fish that are caught, but their total coverage of the fleet can often be limited due to budgets and regulations.  The Study Fleet program at the Northeast Fisheries Science Center collects self-reported catch amounts (landed and discarded) from commercial vessels. The program has been ongoing for over ten years and has recorded thousands of individual tows. For certain species and years, the Study Fleet program has a greater number of reported tows than NEFOP. We compared NEFOP and Study Fleet data, and estimated discards from the two programs. In general the discard estimates were similar; suggesting that self-reported discard estimates could be used to augment observer data if collected from an appropriately designed sampling program.