Sentinel Fisheries – About
The primary objective of a sentinel fishery program is to develop time series of abundance indices to be used in the assessment process of cod stocks. The northern Gulf of St. Lawrence sentinel fishery program became the first program on the Atlantic coast to incorporate abundance indices into stock abundance assessment analyses. Since 1998, four of the five abundance indices coming from areas 3Pn and 4RS are used to calibrate the assessment of this stock come from the sentinel fisheries.
There are many ways to establish abundance indices. For this reason, the various sentinel fisheries that have been developed on the Atlantic coast are not all identical. They were developed in collaboration with fishermen’s associations to address certain issues in a specific way. This site is providing details on the unique aspects of the northern Gulf cod sentinel fisheries.
In the early 1990s, the abundance of cod on the Atlantic coast of Canada had declined so much that the federal government was forced to establish moratoriums on commercial fishing for these stocks. The main factors contributing to this situation were overfishing, poor environmental conditions, the increase of seal populations, and overestimates in the abundance of cod stocks. The closure of the fishery had the unfortunate result of limiting information on stock trends. The Fisheries Resource Conservation Council (FRCC) therefore recommended the establishment of sentinel programs involving a number of fishermen in order to monitor the evolution of cod stocks. The program was implemented in the fall of 1994, the first year of the moratorium on the northern cod fishery in the Gulf of St. Lawrence (3Pn, 4RS).
Review of the sentinel fisheries programs
After eight years of activities, all sentinel fisheries programs on the Atlantic coast were reviewed at a workshop in November 2001. Because issues concerning cod differed among regions and since the industry was involved in the design of the sentinel programs in their respective areas, the programs did not all evolve in the same direction. However, the main objective was found to be the same in all areas; to develop abundance indicators for the various cod stocks, by involving the industry in controlled fishing activities.
The review looked at:
- An inventory of the various programs
- Regional approaches to the structure of the programs
- Quantity and quality of data
- Data treatment and assessment
- Other species and research
- Efficiency and cost effectiveness
- Industry perspectives on sentinel programs
- The future of sentinel
To learn more, refer to the proceedings.
For the cod of the Northern Gulf of St. Lawrence (3Pn, 4RS), it was apparent that there was some oversampling and that the quality of information and the integrity of the database could be maintained by reducing some activities and funding. For the fixed gear sentinel program, the number of sites was reduced from 48 to 32 (-33%). As for the mobile gear stratified random sentinel surveys, they were also reduced from two surveys per year (July and October) to one; the July survey. This optimisation of the Northern Gulf groundfish sentinel program created savings of $557,000 on the previous budget of $1,621,000, for a reduction of 34%. The annual budget for the Northern Gulf sentinel program is $1,064,000 since 2003.
The savings realized in the Northern Gulf of St. Lawrence through the review of the sentinel program have remained available to the industry of the region in a new initiative; the Fisheries Science Collaborative Program (FSCP). The groundfish sentinel program and the FSCP will receive a stable funding for three years (fiscal years from 2003 to 2006).
Scope of the project
At the start of the program in 1994, the participating fishermen have received some training at Memorial University in St. John’s or at the Centre spécialisé des pêches de Grande-Rivière. Each fisherman also received specific training on the sampling protocols for sentinel fisheries; this training was given Fisheries and Oceans Canada staff and the project coordinators. Efforts were also made to keep the same fishermen from one year to the next; this would minimize the risk of error, ensure a growing involvement on the part of fishermen, maintain the optimum quality of work and facilitate the return of gathered information.
Spatial coverage is extensive. Each year, we can expect to have about 900 one-day fishing trips on the fixed gear side (see map below: positions for fishing activities realised in 2003) and about 300 mobile gear tows.The sentinel fisheries on the west coast of Newfoundland and Labrador involve 21 sites spread out along the coast between Red Bay and Grand Bruit, and there are 11 fishing sites along the Lower North Shore of Quebec from Sept-Iles to Lourdes-de-Blanc-Sablon. The trawlers perform one mobile survey a year in early July. In Newfoundland, five vessels are needed to cover all of 3Pn and 4R; in Quebec, four vessels share 4S and the north of 4T.
Protocols differ according to the type of gear used (fixed or mobile). For fixed gear (longlines, gillnets), the traditional knowledge of the inshore fishermen is used. Consequently, they fish 3 days a week for 13 weeks on their fishing grounds, using conventional gear on traditional dates. These three days of fishing activity are financed exclusively by the sentinel fisheries program. However, some criteria must be respected such as the soak time.
Mobile gear fishermen’s activities are similar to the scientific survey conducted by Fisheries and Oceans staff each year on board the NGCC Teleost. In other words, they follow a so-called “stratified random” sampling plan. This method divides the area to be sampled (the northern Gulf of St. Lawrence) according to depth. This parameter (depth) was chosen because it is more likely to influence the distribution of cod. The following depth strata are used: 20-50 fathoms1, 51-100 fathoms, 151-200 fathoms and 201 or more fathoms. Trawlers must perform one tow lasting no more than 30 minutes at a towing speed of 2.5 knots2 in fishing areas determined by depth. A minimum tow of 15 minutes is required for the fishing activity to be significant. A total of nine trawlers conduct one survey a year in July. For given survey, 300 fishing tows are carried out at predetermined fishing stations that will cover the area as a whole. Only one type of trawl is used on these nine vessels. The gear has been calibrated to sample the same area on each tow. The trawls are all lined with fine netting that makes it possible to catch specimens as young as one year (~ 7 cm). This makes it necessary to have observers on board vessels at all times when trawling surveys are being conducted. The observers work for BIOREX in Quebec and SEAWATCH in Newfoundland.
The fishermen are required to perform the following basic work:
- Keep a log describing the gear used, fishing effort, fishing site and total weight of each species caught;
- Measure the size of the fish caught.
Numerous initiatives are added to this:
- sampling of otoliths to determine the age of fish;
- sampling of stomachs to determine the diet of fish;
- whole cod sampling to assess the condition of individual fish;
- deployment of temperature sensors to help analyse fish habitats;
- tagging program to find out more about migrations and assess fishing pressure;
- specific sampling to meet the needs of researchers (vertebrae, blood samples…);
- tagging of Atlantic Halibut;
- by-catches of marine mammals;
- herring and capelin samples for analysis at the Maurice Lamontagne Institute (MLI).
Sentinel fisheries have made it possible to conduct a number of specific analyses:
- effect of fixed gear immersion time on catch rates;
- effect of fixed gear saturation on catch rates;
- analyses of overlapping data from trawl surveys and fixed gear fisheries in July and October;
- study of selectivity between 5½ -inch (140 mm) and 6-inch (152 mm) gillnets
- selectivity study between longlines using traditional J hooks (J #16) or circle hooks (C #12);
- mixing of stocks;
- assessment of mortality due to tagging;
- thesis subjects for graduate students (diversity indexes, environmental effects on catch rates of fixed gear).
Information from the northern Gulf sentinel fisheries is used not only in the assessment of cod stocks, but also in assessments of turbot, redfish, Atlantic halibut, herring, capelin and witch flounder.
The information collected by fishermen is relayed to the offices of fishermen’s associations for verification, validation and capture using programs designed specifically for the sentinel fisheries.
We wish to thank all of the sponsors, coordinators, fishermen and observers involved in the sentinel fisheries program for their devoted work and their efforts to make the program a real success. We also wish to thank the Fisheries Resource Conservation Council for their endorsement and their open attitude toward the sentinel fisheries program.
A partnership between fishermen and scientists from Fisheries and Oceans Canada