Research Document - 2003/059
Lobster stock status in the Gaspé (LFAs 19, 20 and 21) in 2002
By Gendron, L., and Savard, G.
Abstract
In 2002, lobster landings in the Gaspé totalled 789 t, a decrease of 17% from 2001 (959 t). Landings in 2002 were 14% below the average for the 1990s and beginning of the 2000s (1990-2001), but 8% above the 25-year average (1977-2001). In the Gaspé in 2002, 94% of landings were from LFA 20, 4 % were from LFA 19 and 2 % were from LFA 21.
The decrease in landings in 2002 can be attributed to a cold fishing season which could have negatively impacted catchability. The 1-mm increase in minimum catch size can account for up to 10% of the drop in certain sectors. The 2001 fall fishing season in 21B has taken part of the annual recruitment, which could explain the decrease in landings the following spring in this area.
In 2002, the CPUE of commercial lobsters was 0.41 lobster/trap, its lowest level since 1986. It was 28% below the average (in number) for 1986-2001 and 18% below the weight average. Larger lobsters partly offset the decrease in the number of lobsters caught. CPUEs measured during the fall fishing season in 21B were on average seven times higher than in spring.
Following the increases in minimum legal size, the mean size of lobsters landed in LFA 20 as a whole increased from 4-5 mm in 2002 compared with 1996, while mean weight rose by about 15%. The proportion of “market” lobsters (³ 83 mm) was 82% in 2002, compared with an average of 49% for 1993-1996. The exploitation rate for commercial-size males reached 88% in 2001 in LFA20. The increase in minimum catch size contributed to reduce to 60 % the exploitation rate for the portion of the stock ³ 76 mm. In LFA 20, the proportion of jumbo lobster (³ 127 mm CTL) accounted for only 0.04% of the catch (in number) in 2002. The mean size of lobsters in LFAs 19 and 21 is bigger than that of lobsters in LFA 20. More jumbo lobsters were also found there, accounting for 4.5% and 1.6% of the catch, respectively.
The results of a simulation model show that with the 5-mm increase in minimum catch size, egg production per recruit (EPR) appears to have increased by approximately 90% from 1996 levels. The objective of the conservation plan to double 1996 EPR levels will be reached with a minimum size of 82 mm. The abundance of berried females has increased in the population but egg production probably mainly comes from first spawners (primiparous).
The conservation measures taken since 1997 have had a tangible, positive impact on lobster stocks. Egg production has increased and the growth potential of lobster is better expressed. Doubling egg production per recruit is the first step in meeting the conservation objectives that are also intended to ensure the distribution of egg production between first spawners and mulltiple spawners and to widen the size structure of stocks. Exploitation rates remain high and need to be reduced. Such high exploitation rates make the fishery heavily dependent on annual recruitment, offset the expected benefits of increasing the minimum catch size, and slow down the increase in the proportion of multiparous females in stocks.
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