The main source of information used in this
report is the Department of Fisheries and Oceans purchase slip database
which records individual trip landings from commercial marine fisheries
in eastern Canada. The study area includes ports from Lismore N.S.,
at the western extreme, throughout St. Georges Bay and extending to
Mabou Mines, Cape Breton at the eastern end (Figure 1). The study
period includes 1985 to 1997, years for which purchase slip data are
easily available. The purchase slip records the CFV number of the
vessel, the gear used, the port of landing, the date of landing, and
the quantity of fish landed.
Figure 1: Fishing ports in the St. Georges Bay ecosystem project
study area.
The number of slips was used
here as a measure of the amount of fishing effort used to
catch the fish. The groundfish fishing trips in St.
Georges Bay are almost all of one days duration, so the
number of slips is an indication of the number of fishing
days. The number of fishing sets or amount of fishing
gear used in the trip is not recorded on the slip
however. This information is normally recorded on fishing
logbooks. Logbook data is available for mobile gear
vessels (otter trawl and seine) since 1991, but it is not
available for fixed gear vessels. A preliminary analysis
of logbook data indicated little interannual variation in
the number of sets made per days fishing for mobile gear
vessels. So, we are fairly comfortable in using the
number of purchase slips as an indication of the amount
of fishing effort.
Catch per unit effort has been traditionally
used as a measure of fishing success and as an index of stock size.
In this report we have used landings per purchase slip as a measure
of catch per unit effort. Its relevance in terms of stock status is
also discussed.
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