Science Advisory Report 2020/050

Assessment of the Estuary and Northern Gulf of St. Lawrence (Areas 13 to 17, 12A, 12B, 12C and 16A) Snow Crab Stocks in 2019

Summary

• For all areas combined, catches totalled 6,386 t in 2019, down 25.6% from 2018 (8,583 t). Quotas were reached in Areas 13, 16 and 16A, and were almost reached (90–95%) in Areas 14 and 15 but they were not reached in Areas 12A, 12B, 12C and 17. The industry cited socio-economic factors as the reason for the failure to reach the total allowable catch (TAC) in Areas 12A, 12B, 12C.
• Anticipated removals in 2020 are lower in all nine areas because of a cyclical and natural decrease in recruitment. The trawl survey conducted in Sainte-Marguerite Bay (Area 16) and in Areas 13 and 14 indicates that Areas 13 to 16 should see improved recruitment within a few years, if ecosystem conditions remain favourable. It should be noted that the post-season survey was not carried out by industry in Area 12A, which increased the level of uncertainty with regard to stock status there. Areas 12B and 12C are more vulnerable than other areas to the gradual warming of deep channel waters, which has been observed since 2012 and is expected to persist or worsen over the next few years. The short- and medium-term outlook for both areas is poor.
• Science made three recommendations for each area (see Outlook). The recommended reductions for the intermediate scenario range from 10% to 40% of landings in 2019, depending on the area.

Outlook

• The outlook for each area includes three possible scenarios for establishing the following season catches. These scenarios have been developed by taking into account an indicator combining the catch rate (standardized catch per unit effort, CPUE) from the commercial fishery of the previous year and the abundance of commercial-size adult males (number per unit effort, NPUE) from the post-season scientific survey, the uncertainty associated with this indicator, and related stock status indicators (crab carapace size and condition, expected recruitment, and level of spermathecal load of females, if available), with the objective of ensuring sustainable resource management. The proposed changes are related to the landings of the last fishing year. The characteristics of each scenario are described below.

Higher scenario

• Greater likelihood of increased harvesting intensity for the upcoming season compared to the previous season;
• Harvest level that may result in fishing mortality exceeding the historical average;
• Harvesting pressure that may not be sustainable in the long term; and
• Likely decrease in abundance compared to the previous year if recruitment remains relatively stable or decreases.

Intermediate scenario

• Likelihood of moderate harvesting intensity for the upcoming season, similar to the previous season;
• Harvest level assumed to maintain fishing mortality close to the historical average; and
• Could maintain the stock at a level of abundance similar to the previous year.

Lower scenario

• Greater likelihood of lower harvesting intensity for the upcoming fishing season compared to the previous one;
• Cautious harvest level assumed to result in fishing mortality below the historical average; and
• Could lead to an increase in stock abundance compared to the previous year or maintain existing biomass over a longer period of time.

Area 17

• The TAC decreased by 15% between 2018 and 2019 to 2,230 t, and was not reached. Landings totalled 1,702 t in 2019.
• The commercial fishery CPUE declined sharply from 2018 to 2019 (-41%). It is below the historical average of the time series, at a value similar to the lowest values observed during the last 25 years.
• Landings were mostly made up of recruits, with a slight decrease between 2018 and 2019 in the proportion of recruits in favour of crabs with a more advanced carapace.
• After a sharp decline in 2018, the commercial abundance index of the post-season survey was down again in 2019, below the average. The values observed on the north and south shores in 2019 show a strong decrease since the last increases observed in 2017.
• The abundance of adolescents 78-95 mm in the post-season survey decreased between 2018 and 2019 and is below the average. However, trends differ between the two shores for adolescents ≥ 95 mm, with a value that increases slightly on the north shore but decreases slightly on the south shore. The 2019 values are, however, below the historical average for both shores and take together.
• The scientific trawl survey carried out in 2019 shows low recruitment for both shores in 2020, with a high abundance of commercial-sized adults observed since 2017. However, the survey of the north shore was incomplete (48 stations out of 68).
• Although the mean weight of the spermathecal load of primiparous females was among the highest ever recorded in the scientific trawl surveys for both shores, the abundance of reproductive females declined sharply in the 2017 and 2019 surveys on the north shore as well as in the 2019 survey on the south shore, dropping to values that were among the lowest in the series for both shores.
• The combined index for both shores decreased by 30% relative to 2018, falling to the lowest value recorded since the time series began in 2000. This sharp decline suggests that the biomass available to the fishery will be even lower in 2020 than in 2019.

Outlook

• A sharp decline in the combined index for the second consecutive year, coupled with the non-attainment of the TAC and the lower recruitment expected in the short and medium term, points to the need to significantly reduce removals in 2020.

Higher scenario: A 25% decrease applied to total landings in 2019.
Intermediate scenario: A 30% decrease applied to total landings in 2019.
Lower scenario: A more than 30% decrease in total landings in 2019.

Area 16

• The TAC decrease by 15% in 2019 to 3,101 t, and was reached.
• The commercial CPUE has been declining since a high CPUE period was observed in 2013–2015 and it was below the historical average with the lowest value observed in 30 years.
• Landings consisted mostly of recruits, with a slightly lower proportion of intermediate-shell crabs.
• With the exception of 2015, the commercial abundance index of the post-season survey has been declining since 2013, when the highest value in the time series was observed. The 2019 value was the lowest since 2002.
• The combined index decreased by 28% compared with 2018, reaching the lowest value in the time series initiated in 1995. This value suggests that less biomass will be available to the fishery in 2020 than in 2019.
• Monitoring of the snow crab population in Sainte-Marguerite Bay suggests that recruitment, in terms of legal crab numbers will be low in 2020 and will increase starting in 2022.

Outlook

• A sharp decline in the combined index for the second consecutive year (22% in 2018 and 28% in 2019), in a context where recruitment to the fishery is expected to decline in 2020, points to the need to significantly reduce the TAC in 2020.

Higher scenario: A 25% decrease applied to total landings in 2019.
Intermediate scenario: A 30% decrease applied to total landings in 2019.
Lower scenario: A greater than 30% decrease to total landings in 2019.

Area 15

• The TAC decreased by 30% to 442.2 t and was almost reached (413.1 t or 93.4%).
• The commercial fishery CPUE declined for a fourth consecutive year and, in 2019, is among the lowest in the time series.
• The average size of crabs observed at-sea in the commercial fishery have been fairly stable over the last 13 years and are among the highest in history.
• Landings in 2019 consisted mainly of intermediate-shell crabs recruits, while recruits decreased.
• The commercial abundance index of the post-season survey has decreased between 2017 and 2019. The abundance of adolescents ≥ 78 mm has been relatively stable in the post-season survey between 2018 and 2019.
• The combined index is down 41% from the 2018 value. This was the fourth consecutive decline. This decline in the index suggests that there will be less biomass available to the fishery in 2020 than in 2019.

Outlook

• A fourth consecutive decline in the combined index in a context where recruitment to the fishery is expected to remain low in the short term suggests that the landings should be reduced in 2020. However, the size of legal males in the commercial fishery remains stable and high, suggesting that the reduction in removals may be less than that observed for the CI.

Higher scenario: A 25% decrease applied to total landings in 2019.
Intermediate scenario: A 35% decrease applied to total landings in 2019.
Lower scenario: A greater than 35% decrease to total landings in 2019.

Area 14

• The TAC decreased by 25% in 2019 to 463 t and was almost reached (438.6 t or 94.7%).
• In 2019, the commercial fishery CPUE declined sharply for the third consecutive year and is at the lowest value since 1991.
• Landings consisted primarily of intermediate-shell crab in 2019.
• Although among the lowest values in the time series, the commercial abundance index of the post-season survey is slightly higher in 2019 compared to 2018.
• The abundance of adolescents ≥ 78 mm has remained low and fairly stable in the post-season survey and trawl survey over the past five years, which suggests that recruitment to the fishery will not increase in 2020.
• The combined index decreased by 11% from 2018 to 2019, which suggests that the biomass available to the fishery in 2020 will be lower than in 2019.

Outlook

• A decrease (-11%) in the combined index with no indication of improved recruitment in the short term suggests that the landings should be reduced in 2020.

Higher scenario: A 5% decrease applied to total landings in 2019.
Intermediate scenario: A 10% decrease applied to total landings in 2019.
Lower scenario: A greater than 10% decrease in total landings in 2019.

Area 13

• The TAC decreased by 25% to 304.5 t and was reached.
• After several years of relatively high values, the commercial fishery CPUE declined sharply from 2017 to 2019, and is among the lowest values in 2019.
• Average size of crabs caught in the commercial fishery decreased over the past three years to below the historical average in 2019.
• Landings consisted primarily of intermediate-shell crab in 2019.
• The commercial abundance index of the post-season survey on the north side of the area is similar between 2018 and 2019 and is at the level of the historical average. The 2019 value for the south side of the area is down from the previous year and is among the lowest values in the historical series.
• In the northern part of the area, the abundance of adolescents ≥ 78 mm from the post-season survey was above the historical average, while in the southern part, it was below the historical average.
• The high abundance of 40–62 mm male crabs in the 2018 trawl survey indicated possible recruitment to the fishery in the medium term.
• In 2018, the abundance of primiparous females reached the highest value recorded in this survey since 1994. In contrast, in 2018 (trawl survey) and 2019 (post-season survey), the mean weight of the spermathecal load of primiparous females was among the lowest values seen since data collection began in 2003.
• The combined index decreased by 15% from 2018 to 2019 and is among the lowest values in the time series. The biomass available to the fishery in 2020 is expected to be lower than in 2019.

Outlook

• The decline (-15%) in the combined index in 2019, coupled with the decrease in the size of legal crabs in the commercial fishery, the low spermathecal load index of primiparous females and the expectation that recruitment will remain low in the short term, all suggest that removals should be reduced in 2020. Taking into consideration other, related indices that were negative, the 2019 value of the combined index was used as a reference for the high scenario.

Higher scenario: A 15% decrease applied to total landings in 2019.
Intermediate scenario: A 25% decrease applied to total landings in 2019.
Lower scenario: A greater than 25% decrease in total landings in 2019.

Area 16A

• The TAC decreased by 24.9% in 2019 to 310 t and was reached.
• The commercial fishery CPUE decreased for a fifth year. The 2019 CPUE is the lowest since the series began in 2004.
• As in 2018, landings consisted of a large majority of recruits in 2019.
• The commercial abundance index of the post-season survey has decreased between 2014 and 2019, with a slight decrease in 2019.
• Although the abundance level remains low, an increase was seen in the abundance of 78–95 mm adolescents in the post-season survey for the fifth consecutive year. During the same period, the abundance of adolescents ˃ 95 mm remained stable.
• The combined index was down for the fifth consecutive year (-12% decrease from 2018 to 2019). This decline in the index suggests that there will be less biomass available to the fishery in 2020 than in 2019.

Outlook

• The decrease in the combined index since 2014 suggests a decrease in total landings in 2020. However, the recruitment is expected to remain stable in the short term.

Higher scenario: A 5% decrease applied to total landings in 2019.
Intermediate scenario: A 12% decrease applied to total landings in 2019.
Lower scenario: A greater than 12% decrease in total landings in 2019.

Area 12C

• The TAC decreased by 25.1% to 192 t, and was not reached (landings of 149.5 t). Some licences were inactive in 2019.
• The commercial fishery CPUE is down for the third consecutive year. The CPUE in 2019 is the lowest values observed in the time series.
• Landings consisted mostly of intermediate-shell crab.
• The commercial abundance index of the post-season survey decreased significantly over the past five years.
• The abundance of adolescents ≥ 78 mm remained low and fairly stable in the post-season survey between 2014 and 2019, which does not suggest an increase in recruitment to the fishery in 2020.
• The combined index decreased for a fifth consecutive year, with a 39% decrease from 2018 to 2019. This decline in the index suggests that there will be less biomass available to the fishery in 2020 than in 2019.

Outlook

• The 39% drop in the combined index, during a period of stable and low recruitment, suggests a sharp decrease in the removals in 2020.

Higher scenario: A 30% decrease applied to total landings in 2019.
Intermediate scenario: A 40% decrease applied to total landings in 2019.
Lower scenario: A greater than 40% decrease applied to total landings in 2019.

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.
• The fishing effort was low in 2019, with landings of 30 t.
• The commercial fishery CPUE from 2016 onwards is at the lowest values observed since 1995.
• 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 consisted mostly of intermediate-shell crabs.
• The commercial abundance index of the post-season survey has been decreasing since 2013 and is close to 0.

Outlook

• The non-attainment of the TAC, low catch rates, small size and low recruitment of snow crab suggest that stock status did not improve in 2019. The short-term outlook is not favourable.
• According to all indicators available in 2019, the biomass is very low and may not be able to support a commercial fishery.

Area 12A

• In 2019, the TAC remained unchanged at 105.5 t, and was not reached (landings of 80.5 t). Some licences remained inactive.
• The commercial fishery CPUE remained similar in 2019 to that of the two previous years, and is among the lowest values observed.
• Landings consisted primarily of intermediate-shell crab.
• The post-season survey was not conducted in 2019 and the CI was not calculated. All abundance indices from the 2018 post-season survey were declining or fairly stable and were among the lowest values observed in the historical series.
• The combined index in 2018 was the lowest value in the time series beginning in 2000.

Outlook

• Commercial fishery yields that are among the lowest in the historical series, combined with the uncertainty resulting from the absence of the post-season survey, point to the need to reduce removals in 2020.

Higher scenario: Same total landings in 2020 as in 2019.
Intermediate scenario: A 10% decrease applied to total landings in 2019.
Lower scenario: A greater than 30% decrease applied to total landings in 2019.

This Science Advisory Report is from the February 11-12, 2020 meeting on the 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 2020/050 (PDF, 5,886 KB)

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