Science Advisory Report 2024/036

Assessment of the Estuary and Northern Gulf of St. Lawrence (Areas 13-17, 12A, 12C and 16A) Snow Crab Stocks in 2023

Summary

Area 17

• The total allowable catch (TAC) in 2023, which was increased to 1,394.0 t from 2022, was reached. Landings in 2023 totalled 1,396.0 t (+15.2%).
• The standardized commercial catch per unit effort (CPUE) rose significantly between 2022 and 2023 (+37.7%) and is close to the historical average [2000; 2022].
• The average size of legal-size crabs sampled at sea was down slightly between 2022 and 2023, and is below the historical average [2000; 2022].
• Half of landings in 2023 consisted of intermediate-shell crabs, and the other half, of recruits.
• The abundance index for commercial-size adults obtained from the post-season survey increased between 2022 and 2023 and is above the historical average. This increase can be observed throughout the fishing area, with the abundance of crabs left by the fishery also above the historical average [2000; 2022]. In contrast, the abundance of recruits to the fishery declined between 2022 and 2023. The abundance of legal- and sublegal-size subadults declined, reaching the lowest values of the time series.
• The results of the scientific trawl survey carried out in 2023 in the Estuary showed high densities of mature females (primiparous and multiparous), which should continue over the next two years. These increased densities can be observed on both sides of the Estuary. The survey results confirm the arrival of a new pulse of recruitment to the fishery, which, in the short term, seems to be stronger along the north shore than the south. High densities of subadult males (40–78 mm) suggest good years of recruitment to the fishery over the medium term, throughout the entire fishing area.
• The mean weight of the spermathecal load of primiparous females has been declining since 2019, with one of the lowest values in the time series being reached.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) obtained from the post-season survey, rose by 32.1% between 2022 and 2023, suggesting that the biomass available to the fishery in 2024 will be greater than in 2023.

Outlook

• The combined index increased between 2022 and 2023 (+32.1%), which suggests that the biomass available to the fishery in 2024 should be greater than in 2023.
• The recruitment of mature females, which is expected to continue over the short term at similar levels, and the low spermathecal load in 2023 suggest that the increase in removals in 2024 should be limited to avoid obtaining a sex ratio that is overly biased towards females.

Higher scenario: A 30% increase relative to total landings in 2023.
Intermediate scenario: A 20% increase relative to total landings in 2023.
Lower scenario: A 10% increase relative to total landings in 2023.

Area 16

• The total allowable catch (TAC) in 2023, which was increased to 2,585.0 t from 2022, was reached. Landings in 2023 totalled 2,552.0 t (+13.3%).
• The standardized commercial catch per unit effort (CPUE) increased in 2023 (+14.2%) for the fourth consecutive year, and is above the historical average [1996; 2022]. Estimated effort for the last three years has been constant and low, and below the historical average [1996;2022].
• The average size of legal-size crabs sampled at sea is decreasing and is currently below the historical average [1996; 2022].
• Two-thirds of the landings in 2023 were recruits, a higher proportion than in previous years [2019; 2022].
• Following two consecutive increases, the abundance index for commercial-size adults obtained from the post-season survey was down slightly in 2023, remaining below the historical average [1996; 2022]. The increase in the index of recruit abundance does not compensate for the reduced abundance of crabs left by the fishery. Dramatic increases continue to occur in the abundance of sublegal-size adults. The average size of adult male crabs declined between 2022 and 2023, remaining below the historical average [1996; 2022].
• The abundance of mature females was high in the western part of the area in the 2023 post-season survey. These females consisted primarily of multiparous individuals.
• The monitoring of the snow crab population in Sainte-Marguerite Bay in 2023 showed that the recruitment of mature females is declining. The abundance of sublegal- size adult males is still high due to the prevalence of early terminal moulting. However, given the high abundance of adolescent males (78–95 mm), recruitment of legal-size males is expected to increase from 2024 onwards.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) obtained from the post-season survey, rose slightly (+5.1%) between 2022 and 2023, suggesting that the biomass available to the fishery in 2024 should be comparable to or higher than in 2023.

Outlook

• The combined index, rose slightly (+5.1%) between 2022 and 2023, suggesting that the biomass available to the fishery in 2024 should be comparable to or higher than in 2023.
• Crab abundance, which is cyclical in nature, appears to be on the upswing as the pulse of primiparous females has come to an end and male recruitment to the fishery is rising.

Higher scenario: A 25% increase relative to total landings in 2023.
Intermediate scenario: A 15% increase relative to total landings in 2023.
Lower scenario: A 5% increase relative to total landings in 2023.

Area 15

• The total allowable catch (TAC) in 2023, which was increased to 322.0 t from 2022, was reached. Landings in 2023 totalled 323.0 t (+36.3%).
• The standardized commercial catch per unit effort (CPUE)—after hitting the lowest values of the time series in the years between 2019 and 2022—increased dramatically between 2022 and 2023 (+92.9%), and is now above the historical average [2000; 2022].
• The average size of legal-size crabs sampled at sea increased between 2022 and 2023, but remains below the historical average [2000; 2022].
• The majority of landings in 2023 consisted of recruits. This percentage has been increasing since 2019, while the percentage of intermediate-shell crabs declined from 47.2% in 2019 to 26.8% in 2023.
• According to the 2023 post-season survey, the abundance index for commercial-size adults is stable and above the historical average [2014; 2022], despite the decline in the abundance of crabs left by the fishery. This is because the decline is offset by increased recruitment. The abundance indices for legal- and sublegal-size subadults increased between 2022 and 2023 to levels above their respective historical averages [2014; 2022]. The average size of adult males has been increasing since 2020, but the 2023 value is still below the historical average [2000; 2022].
• Although the abundance of primiparous females has declined, the mean spermathecal load has increased to among the highest values of the time series [2008; 2023].
• All the survey indicators point to increasing levels of recruitment to the commercial fishery, and this trend is expected to continue in the short and medium term.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) obtained from the post-season survey, rose by 31.8% between 2022 and 2023, suggesting that the biomass available to the fishery in 2024 will be greater than in 2023.

Outlook

• The combined index, which was at the lowest values between 2019 and 2021, increased between 2022 and 2023 (+31.8%), which suggests that the biomass available to the fishery in 2024 should be higher than in 2023.
• Crab abundance, which is cyclical in nature, appears to be on the upswing as the pulse of primiparous females has come to an end and male recruitment to the fishery is increasing.

Higher scenario: A 40% increase relative to total landings in 2023.
Intermediate scenario: A 30% increase relative to total landings in 2023.
Lower scenario: A 20% increase relative to total landings in 2023.

Area 14

• The total allowable catch (TAC) increased between 2022 and 2023 to 388.0 t, and it was reached with landings of 377.0 t (+21.3%).
• Following an increase between 2020 and 2022, the standardized commercial catch per unit effort (CPUE) remained stable in 2023 (+0.9%) and is still below the historical average [2000;2022].
• The average size of legal-sized crabs sampled at sea increased slightly between 2022 and 2023, but is below the historical average [2000;2022].
• Landings in 2023 consisted primarily of intermediate-shell crabs and recruits, in proportions similar to the previous two years.
• According to the 2023 post-season survey, the abundance index for legal-size adults, which consisted mainly of crabs left by the fishery, was down slightly. Recruit abundance decreased for the third consecutive year, while the abundance of subadults has remained very low for the last three years. Since 2016, the average size of adult male crabs has been in decline, reaching a historical low in the last two years.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) from the post-season survey, is stable (-3.5%) between 2022 and 2023, which indicates that the biomass available to the fishery in 2024 should be similar to that in 2023.

Outlook

• The combined index is stable (-3.5%) between 2022 and 2023, which indicates that the biomass available to the fishery in 2024 should be similar to that in 2023.

Higher scenario: A 10% increase relative to total landings in 2023.
Intermediate scenario: Status quo relative to total landings in 2023.
Lower scenario: A 10% decrease relative to total landings in 2023.

Area 13

• The total allowable catch (TAC) increased between 2022 and 2023 to 206.8 t, and it was reached, with landings of 200.0 t (+6.4%).
• The standardized commercial catch per unit effort (CPUE), which had declined between 2015 and 2021, increased for the second consecutive year (+19.0%), but is still below the historical average [2000; 2022]. This increase was more pronounced in the southern part of the area.
• In 2023, the dockside sampling of legal-size crabs indicated that the average size, down since 2017, was below the historical average [2000; 2022] and at the 2002 pre-moratorium levels.
• Landing in 2023 consisted mainly of recruits (83.3%).
• The abundance index for commercial-size crabs caught in the post-season survey in 2023 was up from 2022. In the northern part of the area, these crabs consisted mainly of recruits. The average size of adult males increased between 2022 and 2023 throughout the area. The abundance of sublegal-size adult males on the northern side of the fishing area remained high in 2023 despite a decline from 2022 to 2023.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) from the post-season survey, is increasing between 2022 and 2023 (+21.1%), suggesting that the biomass available to the fishery in 2024 will be greater than in 2023.

Outlook

• The combined index is increasing between 2022 and 2023 (+21.1%), which suggests that the biomass available to the fishery in 2024 should be higher than in 2023.
• According to data from the post-season survey in the northern side of the fishing area, the pulse of primiparous females appears to be over. The abundance of subadults was down throughout the area, which suggests that recruitment to the fishery could decline in the medium term.

Higher scenario: A 20% increase relative to total landings in 2023.
Intermediate scenario: A 10% increase relative to total landings in 2023.
Lower scenario: Status quo relative to total landings in 2023.

Area 16A

• The total allowable catch (TAC) increased between 2022 and 2023 to 294.0 t, and it was reached, with landings of 290.0 t (+18.7%).
• After dropping to very low values between 2017 and 2022, the standardized commercial catch per unit effort (CPUE) increased sharply between 2022 and 2023 (+69.2%), and is now at the historical average [2002; 2022].
• The average size of legal-size crabs sampled at sea decreased between 2022 and 2023, and is below the historical average [2000; 2022].
• Landings in 2023 consisted mainly of recruits, which have made up an increasing proportion of landings since 2020.
• The 2023 post-season survey suggests that the abundance of commercial-size adults (consisting mainly of recruits) and legal-size subadults is very much on the rise. The abundance of crabs left by the fishery remains very low. The average size of adult male and adolescent crabs increased between 2022 and 2023 but remains below their respective historical averages [2002; 2022].
• The results of the post-season survey indicate a high density of multiparous females. All the survey indicators point to increasing levels of recruitment to the commercial fishery, and this trend is expected to continue in the short and medium term.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) obtained in the post-season survey, rose steeply between 2022 and 2023 (+95.0%), after declining to its lowest value in 2021. This increase suggests that the biomass available to the fishery in 2024 should be greater than in 2023.

Outlook

• The combined index, after declining during the 2014-2021 period, has increased over the last two years, suggesting that the biomass available to the fishery will increase in 2024.
• Crab abundance, which is cyclical in nature, appears to be on the upswing as the pulse of primiparous females has come to an end and male recruitment to the fishery is increasing.

Higher scenario: A 40% increase relative to total landings in 2023.
Intermediate scenario: A 30% increase relative to total landings in 2023.
Lower scenario: A 20% increase relative to total landings in 2023.

Area 12C

• The total allowable catch (TAC) in 2023 was reduced to 67.0 t from 2022, and was reached with landings totalled 64.0 t (-3.0%). Landings in 2023 are the lowest since the creation of the area.
• The commercial catch per unit effort (CPUE), which was at its lowest levels between 2019 and 2022, has since skyrocketed (+195.3% between 2022 and 2023) to slightly above the historical average [2001; 2022]. The estimated effort in 2023 was the lowest it has been since 2001.
• The average size of legal-sized crabs sampled at sea increased for the second consecutive year, but remains below the historical average [2001;2022].
• According to dockside sampling, the proportion of recruits was up for the second consecutive year, and recruits made up the majority of landings in 2023.
• The results of the 2023 post-season survey suggest that the abundance of legal-size crabs, consisting mainly of recruits, is on the rise. However, it is still below the average for the time series [2014; 2022]. The abundance of crabs left by the fishery declined between 2022 and 2023 and remains very low. The average size of adult crabs has risen slightly, but is still below the historical average [2001; 2022].
• The abundance of subadults (78–95 mm) has risen steadily since 2019, reaching the highest value of the time series [2014; 2023] in 2023. Furthermore, in the last two years, the abundance of adults smaller than 95 mm reached the highest levels recorded since 2014.
• The combined index, derived from the commercial CPUE and the number per unit effort (NPUE) obtained from the post-season survey, rose steeply (+160.4%) between 2022 and 2023. This suggests that the biomass available to the fishery in 2024 should be greater than in 2023.

Outlook

• The combined index rose sharply between 2022 and 2023 (+160.4%), suggesting that the biomass available to the fishery in 2024 should be higher than in 2023.
• The cyclical pattern of crab abundance appears to be in an upward phase as the pulse of primiparous females has come to an end and male recruitment to the fishery is increasing. On the other hand, the size of adult crabs has remained low in the last three years despite an increase in average size in 2023.

Higher scenario: A 160% increase relative to total landings in 2023.
Intermediate scenario: A 120% increase relative to total landings in 2023.
Lower scenario: A 80% increase relative to total landings in 2023.

Area 12A

• At 45.0 t, the total allowable catch (TAC) in 2023 remained similar to that in 2022. The TAC was not reached due to socio-economic reasons. Landings in 2023 totalled 39.0 t (-9.3%).
• As part of the development of a precautionary approach for Area 12A, limit thresholds were formulated for two standardized commercial biomass indicators: standardized commercial catch per unit effort (CPUE) and standardized CPUE for legal-size males based on the post-season survey (CPUE95). Combining the status of the two indicators using a scoring grid makes it possible to establish a limit reference point (LRP) and situate the stock in relation to the LRP.
• The standardized CPUE, which reached one of the lowest values of the time series in 2022, increased in 2023. The probability of the moving average for the previous two years being below the limit threshold established for this indicator is 76%. 
• Landings in 2023 consisted primarily of intermediate-shell crabs (78.8%).
• The post-season survey was conducted later than usual in 2023. The CPUE95, which peaked in 2011, declined to its lowest value between 2011 and 2021. Although the CPUE95 increased between 2022 and 2023, the probability of the moving average for the previous two years being below the limit threshold established for this indicator is 100%. 
• On the basis of the two commercial biomass indicators combined, the Area 12A snow crab stock has been in the critical zone since 2015, according to the precautionary approach being developed.

Outlook

• Considering that the precautionary approach is under development and that the Area 12A stock remains in the critical zone despite an improvement in the primary commercial biomass indicators between 2022 and 2023, removals in 2024 should be as low as possible and should not exceed the 2023 landing values or thereabouts in order to promote rebuilding of the snow crab stock.

This Science Advisory Report is from the regional peer review meeting of February 14-16, 2024 on the Assessment of the Estuary and Northern Gulf of St. Lawrence Snow Crab Stocks (Areas 12A, 12C, 13, 14, 15, 16, 16A and 17). 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 2024/036 (PDF, 6,426 KB)

Data sets:

• Commercial catches sampling program in the Estuary and Gulf of St. Lawrence – snow crab (Chionoecetes opilio)

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