Wolffish Relative Occurrence in the Gulf of Saint Lawrence

Spatial distribution of the relative occurrence of Spotted Wolffish, Atlantic Wolffish, and Northern Wolffish in the annual DFO groundfish research surveys conducted by the Québec (1978-2008) and Gulf (1971-2008) regions. The data are aggregated by 100 km² cells. The probability of catching a spotted wolffish in a set and within a cell (relative occurrence) was calculated as the ratio of the number of sets in which a species was recorded and the total number of sets made. This method allows the mapping of catch and effort for numerous time series based on data from different programs in both the whole study area (research surveys and Sentinel Fisheries using bottom trawls and a random stratified design) or in specific areas within the Gulf.