Science Advisory Report 2021/047

Assessment of the Estuary and Northern Gulf of St. Lawrence (Areas 13 to 17, 12A, 12B, 12C and 16A) Snow Crab Stocks in 2020

Summary

Area 17

• From 2019 to 2020, the total allowable catch (TAC) decreased by 42.7% to 1,277 t, and it was reached (corresponding to a 22.2% decrease in landings between 2019 and 2020).
• The commercial fishery CPUE increased from 2019 to 2020 (+12.0%), but is below the historical average of the time series, at a value similar to the lowest values observed since 1991.
• No indicators based on dockside or sea sampling data are available for the 2020 fishing season (provincial COVID 19 health measures).
• The commercial abundance index of the post-season survey remained steady throughout the 2018–2020 period, with the lowest values seen since 2000. Values from both the North Shore and South Shore indicate low commercial abundance levels in 2019 and 2020.
• Abundance indices of the post-season survey for adolescents with a carapace width of between 78 and 95 mm and of 95 mm and above decreased over the 2018–2020 period. For adolescents under 95 mm in 2020, the index was the lowest in the time series (2000–2020), while the index value was slightly below the historical average for adolescents measuring 95 mm and over. No increase in recruitment to the fishery is expected in 2021.
• The decrease in the mean weight of the spermathecal load of primiparous females between 2019 and 2020 suggests an increase in the number of primiparous females.
• The two favourable thermal habitat indices for both large and small snow crabs present a downward temporal trend over the 1990–2020 period.
• The combined index increased by 7.3% between 2019 and 2020. The 2019 and 2020 values are among the lowest in the time series, however. As a whole, stock status indicators do not suggest an increase in the biomass available to the fishery in 2021.
• Scientific survey data indicate an upturn in recruitment to the fishery in the medium term.

Outlook

• The combined index increased slightly between 2019 and 2020 (+7.3%), but was among the lowest values in the time series because of the low commercial biomass in the post-season survey. As a result, no increase in the biomass available to the fishery is expected in 2021.Given the increase in primiparous female density, these indicators suggest a decrease in harvesting in 2021 in order to prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.

Higher scenario: A status quo compared to total landings in 2020.

Intermediate scenario: A 15% decrease applied to total landings in 2020.

Lower scenario: A more than 15% decrease applied to total landings in 2020.

Area 16

• The 2020 TAC of 2,326 t decreased by 25% from 2019 and was reached (landings of 2,300.3 t).
• The catch per unit effort (CPUE) for the commercial fishery increased slightly (+16.1%) in 2020 despite decreasing over the 2016–2019 period. Despite this increase, the 2019 and 2020 values are the lowest observed since 1991.
• No indicators based on sea sampling data are available for the 2020 fishing season (provincial COVID 19 health measures).
• Dockside data are limited but indicate that landings primarily consisted of recruits and that the proportion of intermediate-shell crabs decreased between 2019 and 2020.
• All the abundance indices (adults and adolescents) in the post-season survey decreased between 2019 and 2020, and 2020 values are among the lowest observed since at least 2007.
• Based on monitoring of the Baie Sainte-Marguerite snow crab population, the biomass available to the fishery is expected to increase beginning in 2023–2024. The density of primiparous females rose sharply in 2020.
• The favourable thermal habitat index for large crabs showed a downward temporal trend over the 1990–2020 period.
• The combined index shows similar values in 2019 and 2020 (-1.2% between 2019 and 2020). The 2019 and 2020 values are the lowest in the time series that begins in 1995.
• All available indicators suggest that the biomass available to the fishery in 2021 will not be greater than that available in 2020.

Outlook

• For the second consecutive year, the combined index has remained at the lowest level in the series, and no increase is expected in the biomass available to the fishery in 2021. Given the increase in primiparous female density, these indicators suggest a decrease in harvesting in 2021 in order to prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.

Higher scenario: A status quo compared to total landings in 2020.

Intermediate scenario: A 15% decrease applied to total landings in 2020.

Lower scenario: A more than 15% decrease applied to total landings in 2020.

Area 15

• The total allowable catch (TAC) decreased by 29.9% between 2019 and 2020 to 310 t, and it was not reached. Landings in 2020 were 262.2 t, which corresponds to a decrease of 36.5% compared to landings in 2019. The start of the fishing season in 2020 was delayed by 3 weeks.
• The commercial fishery CPUE (catch per unit effort) in 2020 was similar to 2019 (+ 4.3% between 2019 and 2020), and is among the lowest values observed over the period 1985-2020.
• No indicator based on at-sea monitoring data was available for the 2020 fishing season (provincial health measures for COVID-19).
• Dockside data was limited, but showed that landings consisted mostly of recruits and crabs of intermediate shell condition in a similar proportion.
• All post-season survey abundance indices for males, adolescents and adults were increasing between 2019 and 2020, and with the exception of the commercial portion of adults, were above their respective historical averages (limited to the period 2014-2020). The increase in biomass available to the fishery should continue in the medium term with the arrival of new cohorts.
• The mean weight of the spermathecal load of primiparous females in the 2020 post-season survey, and abundance of primiparous females in the previous post-season survey in 2019, suggested that the abundance of primiparous females was high in 2019-2020.
• The combined index increased by 56.7% between 2019 and 2020, after 4 consecutive years of decline.
• The available indicators suggest that the biomass available to fishing in 2021 will be greater than that of 2020.

Outlook

• The combined index increased between 2019 and 2020 (+ 56.7%), foreseeing a greater biomass available to fishing in 2021. However, the density of mature females, which is supposedly still high, suggest limiting the increase in harvest in 2021 in order to prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.

Higher scenario: A 30% increase applied to total landings in 2020.

Intermediate scenario: A 20% increase applied to total landings in 2020.

Lower scenario: A 10% increase applied to total landings in 2020.

Area 14

• The total allowable catch (TAC) decreased by 14.7% between 2019 and 2020 to 395 t, and it was not reached. Landings in 2020 were 348 t, which corresponds to a decrease of 20.7% compared to landings in 2019. The opening of the fishery season was delayed by 2 weeks in 2020.
• The commercial fishery CPUE (catch per unit of effort) in 2020 was similar to that of 2019 (-1.59% between 2019 and 2020), and is among the lowest values observed over the period 1985-2020 .
• No indicator based on at-sea or dockside monitoring data is available for the 2020 fishing season (provincial health measures for COVID-19).
• All post-season survey abundance indices for males, adolescents and adults increased between 2019 and 2020, except for older commercial males which are decreasing. The commercial abundance of 2020 was composed mostly of recruits in the post-season survey. The increase in the biomass available to the fishery should continue in the medium term with the arrival of new cohorts.
• No scientific trawl survey took place in 2020 (COVID-19), but the 2018 survey indicated an increase in recruitment to the fishery in the medium term.
• Data on the mean weight of spermathecal load of primiparous females during the post-season survey in 2020, and the density of primiparous females during the trawl survey in 2018 suggest that the abundance of mature females was still high in 2020 after a peak in 2018-2019.
• The thermal habitat index favourable to large and small crabs showed an increasing temporal trend over the period 1990-2020.
• The 2020 combined index was comparable to 2018 and 2019 (+ 5.4% between 2019 and 2020), and among the lowest values observed over the period 1998-2020.
• The indicators suggest that the biomass available to the fishery in 2021 should be similar to that of 2020.

Outlook

• The combined index remains, for a second consecutive year, among the lowest values in the series. The biomass available in 2021 should be comparable to that of 2020. The expected high abundance of recruits, associated with the densities of mature females supposedly still high, suggest limiting the increase in removals in 2021 in order to limit white crab mortality and prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.

Higher scenario: A 10% increase applied to total landings in 2020.

Intermediate scenario: A status quo compared to total landings in 2020.

Lower scenario: A decrease compared to total landings in 2020.

Area 13

• The total allowable catch (TAC) decreased by 19.9% between 2019 and 2020 to 244 t, and it was not reached. Landings in 2020 were 213 t, which corresponds to a decrease of 29.5% compared to landings in 2019. The fishing season started with a delay of at least 2 weeks for a good part of the fleet.
• The commercial fishery CPUE (catch per unit of effort) in 2020 was similar to that of 2019 (+ 0.3% between 2019 and 2020), and was among the lowest values observed over the period 1988-2020.
• No indicator based on at-sea or dockside monitoring data was available for the 2020 fishing season (provincial health measures for COVID-19).
• All the abundance indices from the post-season survey carried out in the north of the area increased sharply between 2019 and 2020, and are above their respective historical averages. The commercial abundance of 2020 consisted mostly of recruits. All indices of the survey carried out in the south of the area have, conversely, decreased or remained stable between 2019 and 2020, and were below their historical average. The observed increase in the biomass available to the fishery is expected to continue in the medium term with the arrival of new cohorts.
• No scientific trawl survey took place in 2020 (COVID-19), but the 2018 survey indicated recruitment to the fishery in the medium term.
• Data on the mean weight of spermathecal load of primiparous females during the post-season survey in 2020, and the density of primiparous females during the trawl survey in 2018 suggest that the abundance of mature females was still high in 2020 after a peak in 2018-2019.
• The thermal habitat index favourable to large and small crabs showed an increasing temporal trend over the period 1990-2020.
• The combined index increased sharply in 2020, after 3 consecutive years of decline (+ 44.7% between 2019 and 2020).
• The indicators suggest that the biomass available for fishing in 2021 will be higher than that of 2020.

Outlook

• The combined index increased sharply in 2020 (+ 44.7% between 2019 and 2020), after 3 consecutive years of decline. The biomass available to the fishery in 2021 will be greater than that of 2020. The expected high abundance of recruits, associated with the densities of mature females supposedly still high, suggest limiting the increase in removals in 2021 in order to limit white crab mortality and prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.

Higher scenario: A 20% increase applied to total landings in 2020.

Intermediate scenario: A 15% increase applied to total landings in 2020.

Lower scenario: A 5% increase applied to total landings in 2020.

Area 16A

• The total allowable catch (TAC) decreased by 12.3% between 2019 and 2020 to 272 t, and was almost reached. Landings totalled 256.7 t in 2020, which corresponds to a decrease of 17% compared to 2019. The start of the fishing season in 2020 was delayed by 4 weeks.
• The commercial fishery CPUE (catch per unit of effort) was comparable between 2019 and 2020 (-4.2% between 2019 and 2020) and the value for 2020 was the lowest since 2002.
• No indicator based on at-sea monitoring data was available for the 2020 fishing season (provincial health measures for COVID-19).
• Dockside data was limited, but indicated that landings consisted of a small majority of recruits, and the proportion of crabs with an intermediate shell condition increased between 2019 and 2020.
• The commercial abundance index from the post-season survey was declining over the period 2014-2020, with a decrease in the average size of adults observed in 2020. The indicators of this survey for adolescents and adults of carapace width less than 95 mm, were however sharply increasing between 2019 and 2020. An increase in the abundance of primiparous females was also observed in 2019. The biomass available to the fishery should increase in the medium term with the arrival of new cohorts.
• The thermal habitat index favourable to small crabs showed an increasing temporal trend over the period 1990-2020.
• The combined index was declining over the 2014-2020 period (-11.1% between 2019 and 2020). This decrease suggests that the biomass available to the fishery in 2021 will not be greater than that of 2020.

Outlook

• The combined index has decreased for a sixth consecutive year (-11.1% since 2019), and no increase in biomass available to the fishery is expected in 2021. In the presence of an increase in the density of primiparous females , these indicators suggest reducing the harvest in 2021 in order to prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.

Higher scenario: A status quo compared to total landings in 2020.

Intermediate scenario: A 10% decrease applied to total landings in 2020.

Lower scenario: A more than 10% decrease applied to total landings in 2020.

Area 12C

• The total allowable catch (TAC) decreased by 50% between 2019 and 2020 to 96 t, and it was not reached (in the context of COVID-19). Landings in 2020 totalled 78.9 t, which corresponds to a decrease of 47.2% compared to landings in 2019. The start of the fishing season in 2020 was delayed by 3 weeks.
• The commercial fishery CPUE (catch per unit effort) increased by 35.6% between 2019 and 2020, but the value observed in 2020 is nevertheless among the lowest observed for 25 years.
• No indicator based on at-sea or dockside monitoring data is available for the 2020 fishing season (provincial health measures for COVID-19).
• The commercial abundance index from the post-season survey is on the rise, after 5 years of consecutive decline. All the indicators of this survey (adolescents or adults, legal size or not) increased between 2019 and 2020. An increase in the abundance of primiparous females was also observed in 2020. The increase in the biomass available to the fishery is expected to increase next year and in the medium term with the arrival of new cohorts.
• The thermal habitat index favourable to large crabs showed a temporal decline over the period 1990-2020.
• The combined index increased for the first time since 2014 (+ 64.8% between 2019 and 2020). This increase suggests that the biomass available to the fishery in 2021 will be greater than that of 2020.

Outlook

• After a decrease over the period 2015-2019, the combined index increased in 2020 (+ 64.8% since 2019), which suggests an increase in the biomass available to the fishery in 2021. However, the yields from the commercial fishery in 2019 and 2020 are the lowest observed over the period 1994-2020 and the TAC was not reached for a third consecutive year. In the presence of an increase in the density of primiparous females, these indicators suggest more caution in establishing the total landings allowed in 2021, in order to prevent an excessively biased sex ratio in favour of females during the recruitment of primiparous females.

Higher scenario: A 30% increase applied to total landings in 2020.

Intermediate scenario: A 20% increase applied to total landings in 2020.

Lower scenario: A 10% increase applied to total landings in 2020.

Area 12B

• In order to address socio-economic considerations and to enable monitoring of yields in this area, the TAC was set at 125 tonnes for 2018 and 2019 and an index fishery of 20 t was implemented in 2020.
• No snow crab fishery, commercial or scientific, was conducted in 2020.
• The fishing effort was low in 2019, with landings of 30 t.
• From 2016 onwards, the commercial fishery CPUE is at the lowest values observed since 1995.
• In 2019, the average size of legal crab caught in the commercial fishery remained similar to that of 2017 and 2018, and is below the historical average.
• Landings in 2019 consisted mostly of intermediate-shell crabs.
• The commercial abundance index of the post-season survey has been decreasing since 2013 and was close to 0 in 2018.

Outlook

• The non-attainment of the TAC, low catch rates, small size and low recruitment of snow crab suggested that stock status had not improved in 2019. The short-term outlook was not favourable.
• According to all indicators available in 2019, the biomass was very low and may not be able to support a commercial fishery.
• In the absence of data on the stock status for 2020, no new recommendation is issued for 2021.

Area 12A

• The TAC decreased by 23.7% between 2019 and 2020 to 80.5 t, and was not reached for socio-economic reasons. Landings totalled 69 t in 2020.
• The commercial fishery CPUE decrease between 2019 and 2020 (-12.3%) and is among the lowest values observed since 1995.
• No indicators based on sea sampling data are available for the 2020 fishing season (provincial COVID 19 health measures).
• Dockside data are limited but indicate that landings consisted of a strong majority of intermediate-shell crabs.
• Other than crabs with a carapace width between 78 and 95 mm (adults and adolescents), which increased between 2018 and 2020 to near the historical average, all abundance indices from the 2020 post-season survey remained rather stable compared with those in 2018 and were among the lowest values observed across their historical series. An increase in the abundance of primiparous females and small males was observed in 2020.
• The favourable thermal habitat index for large crabs showed a downward temporal trend over the 1990–2020 period.
• The combined index decreased by an average of 2.8% per year in comparison with the 2018 value, and the 2020 value was the lowest in the time series.
• All available indicators suggest that the biomass available to the fishery in 2021 should not be greater than that available in 2020.

Outlook

• The combined index decreased by 2.8% per year on average between 2018 and 2020 to reach the lowest value in the time series, and performance during the commercial fishery in 2020 was among the lowest in 25 years. In addition, the increase in the abundance of primiparous females in 2020 suggests that a sufficient abundance of males is needed to avoid obtaining a sex ratio that is overly biased towards females during primiparous female recruitment. These indicators suggest a decrease in harvesting in 2021.

Higher scenario: A status quo compared to total landings in 2020.

Intermediate scenario: A 15% decrease applied to total landings in 2020.

Lower scenario: A more than 15% decrease applied to total landings in 2020.

This Science Advisory Report is from the February 16-18, 2021 Regional Advisory Process on Assessment of the Estuary and northern Gulf of St. Lawrence Snow Crab stocks. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2021/047 (PDF, 3,246 KB)

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