地表鱼光学拖网测量:缅因湾西部大西洋鳕鱼(Gadus morhua)的视频拖网测量.

Optical Trawl Surveys of Groundfish: A Video Trawl Survey of Western Gulf of Maine Atlantic Cod (Gadus morhua).

Optical trawl surveys provide a non-invasive method for quantifying groundfish populations and can be used to complement or enhance traditional bottom trawl survey data. This protocol describes the School for Marine Science and Technology (SMAST) video trawl survey, an optical trawl system developed in collaboration with commercial fishermen to assess groundfish abundance and distribution in the Western Gulf of Maine. Cameras and lights were mounted within the codend of a modified commercial trawl to record fish as they passed through the open net. Net mensuration sensors, environmental sensors, and GPS were integrated to calculate area swept and derive density and biomass estimates. The example survey followed a stratified random design, completing 47 tows during a 10-day cruise in spring 2024. Video data were annotated to enumerate target species and validated with periodic closed-codend tows, and representative results for Atlantic cod were presented. This protocol demonstrates a replicable and minimally invasive approach for conducting optical trawl surveys of groundfish that provides high-resolution spatial and abundance data while reducing catch mortality. The method can be adapted to other demersal species and habitats to support fishery-independent monitoring, stock assessment, and ecological research.