Science Advisory Report 2022/040

Assessment of the Estuary and Northern Gulf of St. Lawrence (Areas 13 to 17, 12A, 12B, 12C and 16A) Snow Crab Stocks in 2021

Summary

Area 17

• Between 2020 and 2021, the total allowable catch (TAC) decreased by 5.0% to 1,213.2 t and was reached. Landings in 2021 totalled 1,217.0 t, down 8.1% from 2020 (1,324.0 t).
• For a second consecutive year, the commercial catch per unit effort (CPUE) rose in 2021 (+11.2% from 2020 to 2021) but remained among the lowest values of the 2000–2021 period.
• Dockside sampling indicated that landings in 2021 were approximately half recruits (crabs of shell condition 1–2), representing a proportion fairly similar to the last sampling in 2019.
• The commercial abundance indicator of the post-season survey remained steady (+5.8% from 2020 to 2021) throughout the 2018–2021 period, with the lowest values seen since 2000. However, for a second year in a row, this indicator rose steadily in the southern portion of the area to near the historical average for this subregion.
• All the post-season survey abundance indicators for adolescent and adult males showed values similar to those observed in 2020. Adolescent abundance levels in the southern part of the area were at the historical average.
• The decrease in the mean weight of the spermathecal load of primiparous females and data from the post-season survey since 2020 suggest an increase in the number of primiparous females.
• The favourable thermal habitat indices for both large and small snow crabs showed a downward temporal trend over the 1990–2021 period. The values observed in 2021 are the lowest in each of the time series.
• The combined index increased by 9.1% between 2020 and 2021. Values from 2019 to 2021 were among the lowest observed throughout the 2000–2021 period.
• Indicators suggest that the biomass available to the fishery in 2022 should be similar to that available in 2021.

Outlook

• The combined index increased by 9.1% between 2020 and 2021. Values from 2019 to 2021 were among the lowest observed throughout the 2000–2021 period. The biomass available to the fishery in 2022 is expected to be similar to that of 2021.
• Given the increase in densities of primiparous females since 2020, these indicators suggest that greater caution should be exercised in establishing total allowable landings in 2022 to avoid obtaining a sex ratio that is overly biased towards females during this period of high reproductive female abundance.

Higher scenario: A 10% increase applied to total landings in 2021.
Intermediate scenario: A status quo compared to total landings in 2021.
Lower scenario: A decrease applied to total landings in 2021.

Area 16

• From 2020 to 2021, the total allowable catch (TAC) decreased by 16.1% to 1,951 t, and it was reached (landings of 1,962.6 t).
• After a sharp decline over the 2016-2019 period, catch per unit effort (CPUE) for the commercial fishery is increasing (+19.4%) in 2021 for a second consecutive year, but remains below the historical average.
• Dockside sampling indicated that landings in 2021 were approximately half recruits (shell condition 1–2), representing a proportion fairly similar to the last sampling in 2019 and 2020.
• The post-season survey commercial abundance index is up (+20.9%) in 2021 after a sharp decline over the 2016-2020 period, but remains among the lowest values observed in 20 years.
• The abundance of male recruits and adolescents > 95 mm was stable in the post-season survey, while the abundance of adolescent and adult males measuring 78–95 mm increased between 2020 and 2021 and remained below the historical average.
• Monitoring of the Sainte Marguerite Bay snow crab population could not be conducted in 2021. The last survey in 2020 predicted that the biomass available to the fishery would increase from 2023-24. At the same time, the density of primiparous females was increasing sharply in 2020, suggesting a high abundance of spawning females in 2021-2023.
• The favourable thermal habitat indices for large and small crabs showed a downward temporal trend over the 1990–2021 period. The values observed in 2021 are the lowest in each of the time series.

• The combined index is up 20.0% from 2020, but remains among the lowest values in the last 20 years. This suggests that the biomass available to the fishery in 2022 should be similar to that of 2021.

Outlook

• The combined index increased (+20.0%) between 2020 and 2021 but remains among the lowest values of the last 20 years. The biomass available to the fishery in 2022 is expected to be similar to that of 2021.

• In the context of an assumed high density of reproductive females for the 2021–2023 period, these indicators suggest limiting increases in removals in 2022 to avoid obtaining a sex ratio that is overly biased towards females.

Higher scenario: A 20% increase applied to total landings in 2021.
Intermediate scenario: A 10% increase applied to total landings in 2021.
Lower scenario: A status quo compared to total landings in 2021.

Area 15

• The total allowable catch (TAC) increased by 5.0% between 2020 and 2021 to 325.5 t, and was nearly reached. Landings in 2021 were 306.0 t, up by 13.6% from 2020 (263.0 t).
• The catch per unit effort (CPUE) for the commercial fishery is stable since 2019 (+1.5% between 2020 and 2021), and the last three years' values are the lowest over the 2000-2021 period.
• In the absence of adequate at-sea sampling program coverage for monitoring the mean carapace width (CW) of commercial males in 2021, dockside data indicate a sharp decline from 2020 to 2021 in the mean CW, which was among the lowest values for the 2000–2021 period.
• Dockside data indicate that the majority of landings (53.3%) in 2021 consisted of recruits (crabs of shell condition 1–2). This proportion increased between 2020 and 2021, while the percentage of intermediate-shell crabs declined from 45.2% to 37.9%.
• The peaks in abundance observed in 2020 in the post-season survey (particularly with respect to adult males 78–95 mm), alongside the return of indicators for 2021 to values near those seen in 2019, increase the uncertainty when comparing 2020 and 2021 values.
• Between 2020 and 2021, the commercial abundance index of the post-season survey declined significantly to the lowest value of the 2014–2021 period.
• All other post-season survey abundance indices for adolescent and adult males declined between 2020 and 2021, and only the abundance indicator for sublegal-size adolescents was above its historical average.
• According to the post-season survey, the abundance of primiparous and multiparous females is high in 2021, while the weight of the spermathecal load is decreasing.
• In 2020 and 2021, high abundances of sublegal-size adolescents and primiparous females were consistent indicators of the upcoming arrival of a pulse of recruitment.
• The combined index increased by 35.4% between 2020 and 2021, and is at the same level as the 2019 value. The 2019 to 2021 values are le lowest values observed over the 2014-2021 period.
• The available indicators suggest that the biomass available to the fishery in 2022 is expected to be less than or equal to that of 2021.

Outlook

• The combined index (CI) is among the lowest values observed in eight years (‑35.4% between 2020 and 2021), with fishing yields that were, over the last three years, the lowest observed in the last two decades and a commercial abundance indicator that returned to the lowest observed value (2019). This last point is a source of uncertainty associated with using the CI to develop scenarios.
• The biomass available to the fishery in 2022 is expected to be less than or equal to that of 2021.
• Given the increase in densities of primiparous females since 2019, these indicators suggest that greater caution should be exercised in establishing total allowable landings in 2022 to avoid obtaining a sex ratio that is overly biased towards females during this period of high abundance of reproductive females.

Higher scenario: A 10% decrease applied to total landings in 2021.
Intermediate scenario: A 20% decrease applied to total landings in 2021.
Lower scenario: A more than 20% decrease applied to total landings in 2021.

Area 14

• The total allowable catch (TAC) decreased by 7.6% between 2020 and 2021 to 365.0 t, and was reached. Landings in 2021 were 362.5 t, up by 4.2% from 2020 (348.0 t).
• The catch per unit effort (CPUE) for the commercial fishery is increasing in 2021 (+30.1% between 2020 and 2021), and the last three years' values are the lowest over the 2000-2021 period.
• In the absence of adequate at-sea sampling program coverage for monitoring the mean carapace width (CW) of commercial males in 2021, dockside data indicate a decline in the mean CW since the last sampling in 2019. The mean CW in 2021 was close to the historical average.
• Dockside data indicate that the majority of landings (55.6%) in 2021 consisted of recruits (crabs of shell condition 1–2). This proportion saw a significant increase between 2019 and 2021, while the percentage of crabs with shell condition 3 and 4–5 dropped from 59.9% to 39.2% and 28.3% to 5.2%, respectively.
• All of the post-season survey abundance indices for adolescent and adult males decreased between 2020 and 2021, with a 2021 value that was among the lowest observed in the 2000–2021 period. Uncertainty remains about the validity of the indicators for 2021 compared with the last trawl survey in 2018, which signalled the arrival of a new pulse of recruitment.

• According to the post-season survey, the abundance of primiparous and multiparous females is high in 2021, while the weight of the spermathecal load remains relatively low.
• The thermal habitat indices favourable to large and small crabs showed an increasing temporal trend over the period 1990-2021.
• The combined index decreased by 34.9% between 2020 and 2021, and is at the lowest value over the 2000-2021 period.
• Indicators suggest that the biomass available to the fishery in 2022 is expected to be less than or equal to that available in 2021.

Outlook

• The combined index is at the lowest value observed over the 2000–2021 period (‑34.9% between 2020 and 2021), with fishing yields that were, for the last three years, the lowest observed in the last two decades and a commercial abundance indicator that is the lowest on record. Although some uncertainty remains on the representativeness of the 2021 post-season survey in terms of the status of the resource, the biomass available to the fishery in 2022 should still be less than or equal to that available in 2021.
• Given the increase in densities of primiparous females since 2019, these indicators suggest that greater caution should be exercised in establishing total allowable landings in 2022 to avoid obtaining a sex ratio that is overly biased towards females during this period of high abundance of reproductive females.

Higher scenario: A 10% decrease applied to total landings in 2021.
Intermediate scenario: A 20% decrease applied to total landings in 2021.
Lower scenario: A more than 20% decrease applied to total landings in 2021.

Area 13

• The total allowable catch (TAC) remained unchanged between 2020 and 2021 to 244.0 t, and was not reached. Landings in 2021 were 199.0 t, down 7.0 % from 2020 (214.0 t). The fishing season was closed 11 days early due to white crabs.
• The commercial fishery CPUE decrease between 2020 and 2021 (-26.5%) and is the lowest value observed over the 2000-2021 period.
• Dockside sampling indicates that landings consisted of a majority (59.7%) of recruits (shell condition 1-2) in 2021, which is up from 2019 (+24.4%).
• The mean carapace width of commercial males sampled at sea and dockside has decreased since the last sampling in 2019 and is among the lowest values for the 2000–2021 period.
• The commercial abundance index of the post-season survey increased between 2020 and 2021 and is now above the historical average. This increase is primarily due to the increased abundance of crabs left by the fishery (shell condition 3–5) on the north side and, to a lesser extent, the increased abundance of recruits on the south side.
• Data on spermathecal load weight in the 2019–2021 post-season surveys and densities of primiparous females in the trawl survey in 2018 suggest that the abundance of reproductive females will remain high following a peak in 2018–2019.
• The thermal habitat indices favourable to large and small crabs showed an increasing temporal trend over the period 1990-2021.
• After a sharp increase in 2020, the combined index remains stable between 2020 and 2021.
• Indicators suggest that the biomass available to the fishery in 2022 should be similar to that available in 2021.

Outlook

• The combined index remains stable in 2021 after a strong increase in 2020. The biomass available to the fishery in 2022 should be similar to that available in 2021.

Higher scenario: A 20% increase applied to total landings in 2021.
Intermediate scenario: A status quo compared to total landings in 2021.
Lower scenario: A decrease applied to total landings in 2021.

Area 16A

• The total allowable catch (TAC) decreased by 9.9% between 2020 and 2021 to 245.0 t, and was reached. Landings in 2021 were 244.2 t, down 5.0% from 2020 (257.0 t).
• The commercial fishery CPUE increase between 2020 and 2021 (+14.3%) but the 2021 value remain among the lowest observed over the 2000-2021 period.
• No indicators based on sea sampling data are available for the 2020 and 2021 fishing seasons.
• Dockside sampling indicates that landings in 2021 consisted of a majority of recruits (over half), similar to 2019 and 2020.
• Different spatial coverage across the post-season survey created some uncertainty in the indicators for 2021.
• The commercial abundance index from the post-season survey was declining over the period 2014-2021.
• The high abundance of sublegal-size adolescents in 2020 and 2021 and of primiparous females since 2019 have been consistent indicators of an upcoming pulse of recruitment.
• The favourable thermal habitat index for small crabs showed a downward temporal trend over the 1990–2021 period.
• The combined index was declining over the 2014-2020 period, but only decreases by 4.2% between 2020 and 2021.
• This decrease suggests that the biomass available to the fishery in 2022 is expected to be less than or equal to that available in 2021.

Outlook

• The combined index was declining over the 2014-2020 period, but only decreases by 4.2% between 2020 and 2021.
• The biomass available to the fishery in 2022 should be less than or equal to that available in 2021.
• Given the high abundance of primiparous females, these indicators suggest a decrease in harvesting in 2022 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 2021.
Intermediate scenario: A 5% decrease applied to total landings in 2021.
Lower scenario: A more than 5% decrease applied to total landings in 2021.

Area 12C

• The total allowable catch (TAC) remained the same between 2020 and 2021 at 96.0 t, and was reached. Landings in 2021 were 91.0 t, up 15.2% from 2020 (79.0 t). The fishing season was closed up to 24 days early due to white crabs.
• The catch per unit effort (CPUE) for the commercial fishery is down in 2021 (-32.8%) compared to 2020 and the last three years' values are the lowest over the 2000-2021 period.
• Dockside sampling indicates that landings were about half recruits (shell condition 1-2) in 2021, which is up from 34.5% in 2019.

• The mean carapace width (CW) of commercial males sampled at sea during the fishing season was at the lowest value observed for the 2001–2021 period (103.2 mm), while the CW of males sampled dockside was at the historical average (110.3 mm).

• Different spatial coverage across the post-season survey created some uncertainty in the indicators for 2021.

• The commercial abundance index of the post-season survey declines markedly between 2020 and 2021, to the lowest values of the 2014-2021 period.

• All indicators for this survey of adults and legal-size adolescents declined between 2020 and 2021, with the exception of 78–95 mm adolescents. The abundance indicator for sublegal-size adolescents was at its highest value for the 2014–2021 period. An increase in the abundance of primiparous females was also observed in 2021.
• From 2020 to 2021, increased numbers of sublegal-size adolescents and primiparous females were consistent indicators of an upcoming pulse of recruitment.

• The thermal habitat index favourable to large crabs showed a temporal decline over the period 1990-2021, and is at the lowest value of the time series in 2021.
• The combined index (CI) is decreasing between 2020 and 2021, and is at the lowest value of the 2014-2021 period. This decrease suggests that the biomass available to the fishery in 2022 is expected to be less than or equal to that in 2021.

• In the context of a very low apparent abundance in the last post-season survey, the relative difference in the CI compared with the previous year was strongly influenced by a difference of only a few crabs per trap in comparison with the previous year.

Outlook

• The combined index (CI) is at the lowest value observed in eight years, with fishing yields that were, over the last three years, the lowest seen in the last two decades and a commercial abundance indicator that is the lowest on record.
• The biomass available to the fishery in 2022 is expected to be less than or equal to that available in 2021.
• Given the increasing densities of primiparous females, these indicators suggest that great caution is needed when setting the total allowable landings in 2022 to prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.
• Scientific consensus has also been reached on proposed adjustments to harvests, which—although they may be smaller than those based solely on the value of the relative change in the CI compared with the previous year—can result in a comparable or lower level of harvesting intensity in the upcoming fishing season compared with the previous season.

Higher scenario: A 20% decrease applied to total landings in 2021.
Intermediate scenario: A 30% decrease applied to total landings in 2021.
Lower scenario: A more than 30% decrease applied to total landings in 2021.

Area 12B

• A 20.0 t index fishery was introduced in 2020 but could not be conducted due to the COVID-19 pandemic. In 2021, it was renewed, and the allocation was achieved with landings of 19.0 t.
• The catch per unit effort (CPUE) of the index fishery was 14.0 kg/trap-day, while the average for the commercial fishery in the 2001–2019 period was 25.7 kg/trap-day. However, the uncertainty associated with the results from 2021 is very high.
• At-sea sampling was limited in 2021, but catches consisted mainly of recruits (shell condition 1–2) during the index fishery (87.8%). Meanwhile, dockside data indicated that the majority (72.8%) of landings from the index fishery were intermediate-shell crabs (condition 3).
• No post-season surveys were conducted in 2020 and 2021.
• The favourable thermal habitat index for large crabs showed a downward temporal trend over the 1990–2021 period. The 2021 value was one of the lowest on record.

Outlook

• Based on the information available, the status of the resource in Area 12B cannot be assessed.

Area 12A

• The total allowable catch (TAC) decreased by 12.7% between 2020 and 2021 to 69.0 t, and it was not reached (mainly for socio-economic considerations). Landings in 2021 were 54.0 t, which corresponds to a decrease of 21.7% compared to 2020 (69.0 t).
• The catch per unit effort (CPUE) of the commercial fishery is decreasing in 2021 (-37.6% between 2020 and 2021), reaching the lowest value over the 2001-2021 period.
• At-sea sampling was limited in 2021, but the mean carapace width of commercial males sampled during the fishing season has been declining and was at the lowest value of the 2001–2021 period.
• Dockside data indicate that two-thirds of the landings were intermediate-shell crabs (category 3).
• Other than adolescent crabs with a carapace width of 78–95 mm, the numbers of which increased between 2020 and 2021 to exceed the historical average, all abundance indices from the 2021 post-season survey were among the lowest values observed across their historical series. Increased abundances of primiparous females and small males were observed in 2020 and 2021.
• The favourable thermal habitat index for large crabs showed a downward temporal trend over the 1990–2021 period.
• Between 2020 and 2021, the combined index (CI) declined by 40.8% to reach the lowest value of the 2001–2021 period.
• In the context of a very low apparent abundance in the last post-season survey, the relative difference in the CI compared with the previous year was strongly influenced by a difference of only a few crabs per trap in comparison with the previous year.
• Indicators suggest that the biomass available to the fishery in 2022 is expected to remain very low.

Outlook

• The combined index is at the lowest value on record for the 2001–2021 period (-40.8% from 2020 to 2021), with fishing yields and a post-season commercial abundance indicator that are at the lowest values observed in the last two decades. The biomass available to the fishery in 2022 is predicted to remain very low.
• Given the increasing densities of primiparous females, these indicators suggest that great caution is needed when setting the total allowable landings in 2022 to prevent an excessively biased sex ratio towards females during the recruitment of primiparous females.
• Scientific consensus has also been reached on proposed adjustments to harvests, which—although they may be smaller than those based solely on the value of the relative change in the CI compared with the previous year—can result in a comparable or lower level of harvesting intensity in the upcoming fishing season compared with the previous season.

Higher scenario: A 20% decrease applied to total landings in 2021.
Intermediate scenario: A 30% decrease applied to total landings in 2021.
Lower scenario: A more than 30% decrease applied to total landings in 2021.

This Science Advisory Report is from the Regional Advisory Meeting of February 16-18, 2022 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 2022/040 (PDF, 9863 KB)

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