Inferring the drivers of discarding practices from observer data to identify appropriate fishery‐specific solutions

Discard patterns are affected initially by catch compositions, which are determined by environmental factors, the fishing gear used, and fishing tactics, and finally by fishers, when they decide which parts of the catch to retain. An understanding of the drivers of discard practices is essential in developing successful discard mitigation measures.

A simple model is applied to 6 Abstracts–Theme Session C European observer data to infer the main causes of discarding by partitioning the discards into four categories based on the length at which the fish are discarded and principal legislative restrictions. These are: (i) fish below the legal minimum landing size (MLS); (ii) fish with no associated legal MLS that are below the minimum length landed (includes protected species and non‐commercial species; (iii) fish with no associated quota that are above the MLS or minimum length landed; (iv) fish with associated quota that are above the MLS or minimum length landed.

The model is applied to data from the full English observer programme and to French, Danish, Greek, and Spanish case study métiers. The proportionate contribution of the different categories is determined, the differences between métiers and areas established as well as any changes over time. The results are used to assess the most appropriate discard mitigation reduction strategies in each case, such as selectivity improvements, markets developments, and aligning fishing opportunities with quota availability.