Analysis of a Comparative Survey Conducted in 2019 and 2020 for Two Different Types of Bottom Trawls Used on Board CCGS M. Perley During the Northumberland Strait Multi-Species Bottom Survey

Abstract

Marked differences in fishing efficiency were observed between the Otter Trawl and the Northumberland Trawl during comparative fishing experiments conducted on CCGS M. Perley in 2019 and 2020. The Northumberland Trawl had a higher fishing efficiency than the Otter Trawl for almost all taxa observed, and this fishing efficiency varied with depth and with the length of captured individuals. A binomial modelling framework yielded estimates of calibration coefficients to be applied to catch data. While uncertain, the application of calibration coefficients is necessary to maintain the continuity of the survey time-series. For American Lobster, catches from the Otter Trawl will need to be corrected for depth and length effects in order for the survey time-series to extend back to 2001. The calibration coefficients obtained for other taxa are presented but may need further refinement prior to inclusion in analyses supporting science advice.