Whiting (Merlangius merlangus) in Division 3a (whg.27.3a) - exploration of rfb-rule

Whiting catches in 3.a are landed both for human consumption and by industrial fisheries. On average, industrial fisheries account for about 17% of the total catch, but length information is not sufficiently available for these fisheries in each year. This document develops an assessment using the rfb-rule, addressing the absence of length data in the industrial fisheries by incorporating length information from survey data. A comparison across several years shows good performance of this approach.

The rfb-rule indicates that the fishing pressure proxy exceeds one, suggesting that relatively few large whiting are present in Division 3.a. This pattern may reflect either overfishing or the movement of larger individuals out of the area. The latter is currently unquantified and unknown. We apply the rfb-rule to the 2024 assessment to evaluate how the advice would change. The rule would have resulted in an advised catch of 457 tonnes for 2025 and 2026, whereas the advice was 455 tonnes based on the rb-rule.