Research Document - 2009/064

History, assessment methods, and regulation of Nova Scotia’s bloodworm (Glycera dibranchiata) harvest

By R.J. Miller

Abstract

The Nova Scotia commercial bloodworm harvest began with exports to the US in 1952; but was first regulated in 2002. By 2008, regulations included limited entry, reporting of daily sales and fishing location, seasons, area closures, and minimum legal size. The recreational harvest was regulated by seasons, minimum size, area closures, possession limit, and licenses. To aid in setting minimum legal sizes, size of maturity was measured in Southwest Nova Scotia and Minas Basin. DFO-directed and harvester-directed methods for surveying worm density and size distribution were developed and found to be robust. The effects of sample size on precision, time of air exposure of the mud, temperature of the mud surface, depth of digging, and variation among harvesters were measured. Depletion of 5 mud flats has been documented. Because of the risk of serial depletion and spawning failure, a precautionary management approach is recommended; this is in agreement with DFO’s emerging species policy. Because interchange of worms between mud flats is probably small, flats should be managed individually. This requires the involvement of harvesters in surveys to determine mean densities relative to a reference point. Failing harvester participation, this recommendation includes alternating the closure of one-half the mud flats each year plus closure of depleted flats, as determined by occasional DFO surveys, until they recover.

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