Catch, effort, location (latitude and longitude), and associated biological data from the Eulachon Migration Study Bottom Trawl surveys on the coast of British Columbia.

Introduction:

The Eulachon Migration Study Bottom Trawl surveys are divided into two parts; the Eulachon Migration Study Bottom Trawl – South (Eul –S) and the Eulachon Migration Study Bottom Trawl – North (Eul-N).

The objectives of these surveys were to learn about the distribution, ecology, and migration timing of Eulachon into and out of the Fraser (Eul-S), Nass, and Skeena River (Eul-N) systems. This was achieved by observing Eulachon spatial and temporal occurrence and biological condition over a wide survey region each month.

EUL-S covered portions of the Strait of Georgia and Juan de Fuca Strait in Pacific Fishery Management areas (PFMA’s) 17-20, 28, 29, and 121. There were nine trips conducted from October 2017 to March 2018 and one trip in January 2019.

Eul-N consists of seven trips conducted between July 2018 and March 2019 mainly in Chatham Sound with sets in Hecate Strait, and Portland Inlet (Pacific Fishery Management areas (PFMA’s) 3, 4, and 104).

Fishing was conducted using the Canadian Coast Guard Research Vessel Neocaligus to tow an American shrimp trawl net (Cantrawl Nets Ltd., Richmond, BC). The horizontal opening of the polypropylene net was estimated to be 34 to 37 feet (10 to 11 m), while the center of the opening had a vertical height of approximately 7 to 9 feet (2 to 3 m). A 0.4” (10 mm) liner was used in the codend. The net was configured with roller gear and 72” (1.8 m) Thyboron Type 2 trawl doors. Tow duration was typically 20 minutes for Eul-S and ranged from 5-20 minutes for Eul-N. The standard hours of fishing were 0700 to 1700 hours, depending on sunrise and sunset in winter months.

These surveys follow a random block design in a targeted depth range of 80 – 200 metres for the Eul-S and 80-300 metres for Eul-N. The surveys were conducted by the Department of Fisheries and Oceans Canada (DFO) and was funded by the Fisheries and Oceans Canada (DFO) National Rotational Survey Fund.