An investigation into methods to calculate effort controls in a multi-species fishery: northern and central Queensland otter trawl case study using data from 2017 to 2021

Abstract

This report investigated how to combine multiple species, with and without stock assessments, into regional trawl effort caps. This was in the form of effort units (EU) for the northern and central regions of the Queensland east coast otter trawl fishery.

Variations in methods (detailed or ratio), spatial inshore and offshore stratifications (filtered or allocated divisions within a region), co-caught adjustments (species proportions from effort or catch data) and different species inclusions were investigated. These comparisons resulted in 64 different effort cap calculations per region. The calculations used data from 2017 to 2021 and stock assessment results from 2023 (Lovett et al. (2023), Fox et al. (2023) and Wickens et al. (2023)).

Some of the 64 effort cap calculations were above, and some were below, the current 2024 effort caps. Considerations are needed to mitigate exceeding species-specific target reference points, to maintain or improve average catch rates per boat-day for economic profit, and to limit bycatch.