4vN Cod Sentinel
Below is CBFHA summary on the data collected from the 2018 sentinel. The data is based on the total number of cod sampled, ranging from smallest to largest, percentage of males/females, their weight, and age maturity. Additionally, the charts indicate the stomach content of the cod and number of by-catch that was caught with the cod.
Atlantic cod (Gadus morhuna) is distributed in the western Atlantic from North Carolina (USA) to Greenland. Cod are a demersal fish, caught on a sunken longline off the coast of Cape Breton. During the sentinel survey, the cod are landed and organized to determine location, time of day, and if any other species were caught as bycatch. The first 50 fish from each location are held and brought back to the lab for sampling. These protocols are in place to monitor groundfish species that have been commercially unavailable and are not showing signs of recovery.
The Cape Breton Fish Harvesters Team is responsible for dissecting and collecting information from the retained fish. We record fish size, sex, maturity stage, weight, and stomach content. We also extract an otolith (a small bone in the ear used to age a fish) and identify all the species that had been consumed. This information is all sent back to DFO to monitor the viability of the cod stock in our fishing ground, 4Vn.
Cod, (genus Gadus), are large and economically important marine fish of the family Gadidae. The species Gadus morhua is found on both sides of the North Atlantic. A cold-water fish, it generally remains near the bottom, ranging from inshore regions to deep waters. These fish have always been a commercially important species. Since at least the 16th century, the Atlantic stock of cod has been exploited for food and fish products. Landings from earliest records were estimated to be between 20,000 and 40,000 tonnes annually. With an increase in technology, landings increased until the early 1970’s with the highest year in 1958 at 100,000 tonnes of cod landed.
In 1974, the first global quotas or Total Allowable Catch (TAC) were imposed on the cod fishery and became more restrictive as the cod stock continued to decline in the mid-1970s. In September 1993, the cod fishery in Atlantic Canada closed due to low abundance of cod.
5 years after the closure of the commercial cod fishery, the Department of Fisheries and Oceans (DFO) opened an index fishery with a small TAC. They monitored the stock with this index fishery allowing the catch of 6,000 tones until 2002, however, there was no report of recovery for these species. This led to the fishing of cod taking a year break. Then, in 2004, the index fishery re-opened with a TAC of 3,000 tonnes. The TAC has fluctuated since 2004, but since 2009 the species has been under moratorium with TAC for bycatch of cod set at only 300 tones.
With the closure of the cod fishery, there was no longer any commercial data available to DFO scientists to use in resource assessments. Upon the recommendation from the Fisheries Resource Conservation Council (FRCC), the sentinel survey program was put in place.
The sentinel survey program is not a commercial fishery but a pre-determined protocol to collect fisheries information on stock viability. This protocol was designed by combining fishery knowledge of traditional fishing areas with scientific protocols to minimize bias and maximize data. DFO stated that the primary objectives of the sentinel survey are to collect information on the distribution, migration, condition, maturity stages, and stomach contents of the fish, as well as to collect water temperature information.
Each vessel involved in the sentinel survey must therefore adhere to strict guidelines that specify gear type, location, soak time, and frequency of sampling trips to sea. Below, you can see the stations identified for sampling from DFO, and the actual sampling coordinates from local fishers all around the Cape Breton Area.
Figure 2. Cod Sentinel stations assigned by DFO (the yellow fish maker) and the drop location of gear (dark blue) along with the haulback site (light blue).
Map also shows the St. Anns Bank Marine Protected Area along the coast of Cape Breton, NS. Canada.
References
1. Canadian Science Advisory Secretariat Gulf Region Science Advisory Report. January 2016. ASSESSMENT OF ATLANTIC COD (Gadus morhua) IN THE SOUTHERN GULF OF ST. LAWRENCE (NAFO DIV. 4T-4VN(NOV. – APRIL) TO 2014
2. SAMPLING PROTOCOLS FOR SENTINEL SURVEYS – LONGLINES 2016 IN THE SOUTHERN GULF OF ST. LAWRENCE. Revised May 2016). Fisheries and Oceans Canada