Initiated in 1995, the 4VsW Sentinel Program utilizes commercial longliners to establish a series of catch rate and abundance indices which could be useful in assessments and management of groundfish resources.
Longline gear allows operations to be conducted in all areas, including inshore waters and on bottom types that DFO could not sample using a survey trawl. The program also provides valuable information on by-catch species, predator prey relationships and environmental conditions necessary to understanding the marine ecosystem. The program features a stratified random survey conducted in September and October of each year. In a stratified random survey, fishing locations are selected by computer within a series of depth strata.
Commercial fishermen had concerns that the data collected from the Sentinel Survey did not provide a true representation of their fishery. In 1996, a commercial index was introduced to reflect normal fishing activity. This allowed participating commercial vessels to fish (under certain conditions) within 4VsW, excluding closed areas. The commercial index was discontinued in 2007, as a result of the Larocque Ruling, as well as a decline in participation over the years.
In 2004, the number of stations for the stratified random survey was reduced from 202 down to 53 stations due to economic reasons. As a result of the large reduction in stations, the program has been limited to a portion of 4W.
The scientific data collected from the program is integrated into existing DFO databases to enhance the accuracy of stock assessments.
Since 2004, three vessels have been contracted to fish at the preselected stations, which are divided into three zones. All participants must follow specific sampling and gear requirements. Each vessel must fish with 1500 #12 circle hooks baited with frozen mackerel and set within a specified six hour period. The fishermen themselves collect scientific data: total catch, specific fish lengths, weights, sex, otoliths, stomachs, water temperatures and CTD (Conductivity, Temperature and Depth) profiles.
The 4VsW Sentinel Program continues to improve the relationship and understanding between fishermen and scientists, as well as promoting fish stock conservation and management objectives.