Research Document - 2012/010
Lobster stock status in the coastal waters of Québec (LFAs 15 to 22) in 2011 and determination of reference points for the implementation of a precautionary approach in the Magdalen Islands (LFA 22).
By L. Gendron and G. Savard
Since 2005, the assessment of lobster stocks in the Quebec waters (Lobster Fishing Areas, LFAs 15 to 22) is performed every three years. The last assessment was performed in 2008. The present document describes the data and analyses that served to determine stock status and provide recommendations for the 2012-2014 fishing seasons. There is no direct measurements of lobster biomass (empirical or analytical) and stock status assessments are based on an examination of four groups of indicators that describe the abundance, demography, fishing pressure and productivity of the stocks in terms of reproduction and recruitment. Stock status assessment is done by examining indicator trends versus the time series of the various data groups. Stock status assessment is done for the three main Quebec regions, i.e., the Magdalen islands (LFA 22), the Gaspé area (LFAs 19, 20 and 21), and for the North Shore (LFAs 15, 16 and 18) – Anticosti Island (LFA 17) area, which accounted, respectively, in 2011, for 71%, 23% and 6% of total Quebec landings. The lobster fishery is an input-control fishery (effort, sizes and protection of berried females). The minimum catch size (MCS) was increased by 6-7 mm in the last 15 years, which contributed to better protect immature lobsters and reach the objective of increasing egg production.
The abundance indicators were quite high in 2011 in the Magdalen Islands: the landings, the catches per unit effort (CPUEs) of commercial lobsters and the commercial density and biomass from the trawl survey were higher than they were in 2008 and above the series average. The average size of commercial lobsters has remained rather stable since 2008 and since the end of the MCS increase in 2003. Exploitation rates of the harvestable male fraction of the population are still high. However, since 2003, fishing mortality for the whole population dropped as a result of the increase in the MCS. The productivity indicators remained high and recruitment indices suggest still high landings in the short term and show excellent potential for maintaining good recruitment to the fishery in the longer term. According to the precautionary approach the lobster stock of the Magdalen Islands is currently in the healthy zone.
The abundance indicators have increased since 2008 in the Gaspé, after a period of marked decrease at the beginning of the 2000s. The 2011 landings were higher compared to 2008, and above the average of the past 25 years. (CPUE) were higher than in 2008 and above the data series average. The average size of commercial lobster has remained stable. Exploitation rates remained high in general in LFA 20, but dropped in areas where there was a noticeable decrease in fishing effort. Fishing mortality for the whole population dropped as a result of the increase in the MCS. Productivity indicators were high in LFA 20 suggesting that recent landing levels could be maintained at least in the short term.
At Anticosti Island, landings have risen since 2008 and in 2011, they were well above the average of the past 25 years. CPUEs were also greater in 2011. However, lobster size structures have changed in recent years and the average size has dropped, which could be explained by the arrival of recruitment. However, the drop in the number of large lobsters suggests exploitation has increased. This could translate into weaker egg production. Lobster landings along the Lower North Shore dropped below the average for the last 25 years. The landings information may have been incomplete or this decrease may reflect a long-term decline in fishing effort. Catches per unit effort remained relatively stable from 2008 to 2011. Few lobsters were measured over the past few years in LFAs 15 and 16, which makes it difficult to assess demographic indicators.
On the whole, the situation is positive for most LFAs, Programs of fishing effort reduction are in progress in a number of LFAs which should contribute to further increase the robustness of the populations. A precautionary approach (PA) based on an empirical method was developed for the lobster fishery in the Magdalen Islands. The limit and upper stock reference points (LRP and USR) and the stock status zones (healthy, cautious and critical) were defined from a stock biomass indicator and in compliance with the DFO operational policy framework. The approach will eventually be improved and developed also for other LFAs.
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