Science Advisory Report 2021/007

Guidance for Setting Reference Points for the Sea Cucumber (Cucumaria frondosa) Fishery in the Maritimes Region, and Status of the SWNB Sea Cucumber Fishery 2019

Summary

• Current stock status indicators for Orange-Footed Sea Cucumber (Cucumaria frondosa) in the Maritimes Region are based on fishery dependent information: catch rates and split weight.
• Caution is warranted when using catch rate-based indicators due to the possibility that catch rates could remain stable as the population declines.
• Limit Reference Points (LRP) were established for Sea Cucumber fishing areas that have been regularly fished, including Southwest New Brunswick (SWNB) Zone 1, 4W Offshore Zones 1 & 2, 4W Mid-shore Zone F, and 4Vs Area of Access 2.
• The highest mean catch rate in each time series was used as the basis for setting LRPs, as a proxy for unfished biomass (B0).
• The LRPs for 4W Offshore Zones 1 & 2, 4W Mid-shore Zone F, and 4Vs AOA2 were set as 20% of Bo (0.045 kg/m2, 0.061 kg/m2, 0.127 kg/m2 and 0.052 kg/m2, respectively).
• The LRP for SWNB Zone 1 was set as 30% of B0 (811.53 kg/hr*m). Reference points for SWNB Zone 1 were more precautionary due to the risk associated with fishing all known available Sea Cucumber habitat in that fishing area.
• Reference points should be re-evaluated as additional fishery independent information becomes available.
• The assessment of SWNB Zone 1 was based on catch rate and split weight indicators.
• The catch rate indicator for SWNB Zone 1 is near the LRP and in the cautious zone. Focus should be on rebuilding.
• In SWNB Zone 1, there has been a decline in the catch rate indicator for the past 14 years; the decline from 2005–2019 was 66%.
• The average split weight indicator in SWNB Zone 1 has declined by 25% since the start of the time series in 2012. Split weight indicates the size distribution of the commercial catch has shifted to become composed of smaller animals.
• It is unknown what level of fishing in SWNB Zone 1 would allow stabilization and recovery of the stock within a reasonable time frame. In 2019, the Total Allowable Catch was reduced to 500 t; however, the catch rate indicator remains near the LRP.
• Reserves and rotational harvesting are some of the options that can be used as effective spatial management tools for assumed low mobility species such as sea cucumber. Broad guidance was given to set aside at least 30% of expected Sea Cucumber habitat from fishing in data-limited situations. Any strategy to set aside areas from fishing should be re-evaluated on a 3–5 year time period to ensure objectives are being met.
• A map of expected C. frondosa habitat has been provided by DFO as guidance for setting aside 30% of habitat on the Scotian Shelf. The map should be updated and validated as more data become available

This Science Advisory Report is from the May 28–30, 2019 regional peer review on the Review of Indicators and Reference Points for the Maritimes Region Sea Cucumber (Cucumaria frondosa), and Status of the southwest New Brunswick Sea Cucumber population. 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 2021/007 (PDF, 1,317 KB)

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