Observations of redfish (Sebastes spp.) escaping a T90 mesh codend

A combination of qualitative and quantitative approaches were used to describe redfish behavior and escape in a T90 (mesh turned 90 degrees) mesh codend of a demersal trawl. Using under water video we show that redfish behavior is important to their escape mechanics and that several concentrated events occur where up to hundreds of redfish escape from the codend at once. Of significance, we document that these escapes are happening at depth, which minimizes redfish mortality once entering the trawl. Previous research with T0 mesh codends showed or assumed that the majority of redfish escape at the surface where mortality is likely extremely high due to the physoclistic biology of redfish. These results further show the benefits of using a T90 mesh codend to reduce the fishing mortality of redfish.

Automated summary

A combination of qualitative and quantitative approaches were used to describe the behavior and escape of redfish in a T90 mesh codend of a demersal trawl. The study revealed that redfish behavior plays a crucial role in their escape mechanics, with several concentrated events where hundreds of redfish escape simultaneously from the codend. Importantly, these escapes occur at depth, reducing redfish mortality once they enter the trawl. Previous research using T0 mesh codends assumed that most redfish escape at the surface, which likely leads to high mortality due to the physoclistic biology of redfish. These findings further support the use of T90 mesh codends to reduce fishing mortality of redfish.