DFO Pacific Groundfish - Hecate Strait Multispecies Assemblage Bottom Trawl Survey

The Hecate Strait Multispecies Assemblage Bottom Trawl survey series consists of twelve surveys that were conducted from 1984 to 2003 by the Pacific Biological Station, Fisheries and Oceans Canada. The main objective of this survey series was to collect detailed catch and biological data on species assemblages in order to develop an ecological basis for mixed species stock assessment in Hecate Strait. These surveys also provided abundance indices for individual species and were a source of information on recruitment.
The surveys were conducted using a combination of charter vessels and two Canadian Coast Guard Research Vessels, the R/V G.B. Reed and R/V W.E. Ricker. To determine haul locations, a grid of 19 km² (10 nautical miles²) blocks were used with an attempt made to establish one trawl site within each 18 metre depth interval within each block. The 1984 survey involved one chartered and one research vessel; all other surveys were single vessel surveys. The Hecate Strait Multispecies Assemblage Bottom Trawl survey series surveyed Pacific Fishery Management areas 4, 5, and 101 to 106. A total of 1,111 number of tows were made with a Yankee 36 trawl net.
This survey series is the predecessor for the present day Hecate Strait Synoptic Bottom Trawl Survey and represents one of the longest running time series of fisheries independent groundfish surveys on the west coast. For further details about the Hecate Strait Multispecies assemblage bottom trawl survey series, a list of reports can be found in the supporting documents section.
The data provided include information about the annual survey trips and fishing events (tows/sets) that are part of this survey series, including the vessel name, dates, times, spatial coverage, gear details, and effort information. Catch information (total weight in kg or counts of individual specimens) is included from successful fishing events. Catches are identified to species or to the lowest taxonomic level possible. Most catches are weighed, but some are too small (“trace” amounts) or too large (e.g. very large Big Skate). Some catches were subsampled and biological data were collected from individual fish specimens, including length, sex, and weight information. Where age structures were collected and processed, fish ages have been included. Relative abundance indices are provided for species that have been captured in every survey of the time series. The coefficient of variation and bootstrapped 95% confidence intervals are provided for each index. The groundfish data synopsis report (Anderson et al. 2019) provides an explanation of how the relative biomass indices are derived.