Work

From behind bars to freedom: understanding the size selection of fish sorting grids

Year: 2025

Type: article

Abstract: Rigid sorting grids are used in demersal trawl fisheries globally. However, in some fisheries, like in the Barents Sea demersal trawl fishery, they have been found to release large quantities of target-sized catch while simultaneously retaining too many undersized fish. Several studies have documented this issue but, an in-depth understanding regarding the exact reasons for these results is still lacking. Thus, the present study investigated whether experiments conducted in the laboratory could shed light on this matter. Predictive models based on these laboratory results, enabled understanding the size selection pattern from fishing trials for three different roundfish species more in detail. The models revealed that the unintended release of target-sized individuals occurs because a significant fraction of the fish entering the trawl squeeze themselves between the sorting grid bars to escape. The unintended retention of undersized individuals could be explained by that many fish contacted the grid with a suboptimal body orientation. The method applied enabled gaining detailed insight on the interaction of fish with sorting grids and could potentially be applied to gain understanding of the performance of other selectivity devices used in trawl fisheries.

Source: Journal of Sea Research

DOI: 10.1016/j.seares.2025.102595

Authors: Nadine Jacques, Bent Herrmann, Manu Sistiaga, Jesse Brinkhof

Institutions: UiT The Arctic University of Norway, Technical University of Denmark, Norwegian Institute of Marine Research

Language: English

Topic: Marine and fisheries research

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDG: Life below water

Open Access status: gold

Estimated APC paid: $2,610