Science Advisory Report 2009/037

Nova Scotia Bloodworm (Glycera dibranchiata) Assessment: A Review of Methods and Harvest Advice

Summary

• Harvesting can have measurable impacts on marine worm densities within a harvest area, although the sustainability of harvest appears to vary by location.
• Survey densities of commercial sized worms at Avonport, Walton, and Yarmouth Harbour dropped significantly after a few years of harvesting, and Yarmouth Harbour showed little evidence of recruitment in the 3 years after opening. Starrs Point and Kingsport have declined in importance as harvest areas over time. While these areas have not been surveyed, it is suspected that their bloodworm abundance has declined. Bloodworm densities in Cheverie remained relatively stable over 3 years with moderate harvest levels, and Goose Bay has remained an important harvest area since the 1950s.
• Mud flats should be managed independently because exchange of worms between flats is probably low and evidence suggests that harvesters can fish down individual flats to low levels. DFO resources are currently insufficient to manage harvest of bloodworms by flat without involving harvesters in surveys.
• A robust survey protocol was developed that harvesters can use to measure worm densities and size distributions.
• A number of management measures are currently in place to support a sustainable harvest of marine worms, including minimum legal size, possession limits for recreational harvesters, seasonal and year-round closures, gear restrictions, and licensing controls. Additional monitoring and enforcement would help to ensure the effectiveness of management controls, particularly minimum legal size.
• Additional measures that would support a sustainable harvest include: closing a flat when density falls below 0.6 worms/m² for worms over the minimum legal size (interim reference point until further evaluation), opening a closed flat when density exceeds 0.8 legal worms/m², and restricting harvesting during spawning. If regular monitoring of individual flats is not implemented then a cautious approach (based on less information) of rotating closures of flats should be substituted.

Complete document (PDF, 384 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.