Fishing power and ecological impact on gulf chondrus crispus irish moss of modified chondrus drag rakes
Pringle, J.D.; Jones, D.J.; Rowe, P.
Canadian Manuscript Report of Fisheries and Aquatic Sciences 1601: 1-20
Chondrus (Irish moss) is a benthic macroalga consisting of a concentric, basal disk (holdfast) which increases in diameter on an annual basis and supports upright fronds (up to 100 or more) which, when harvestably mature, are approximately 12 cm in height and extensively branched. Generally, only a few of the fronds on a single plant are harvestably mature. Harvesting of Chondrus with drag rakes is conducted throughout nearshore southern Gulf of St. Lawrence waters by approximately 400 inshore boats. The typical drag rake has 40 tines, 20 cm long, with cross-sectional dimensions of 12.5 mm .times. 12.5 mm and a distance between the tines of 6.5 mm. Two basic methods of harvesting are employed. The wincher method uses winches, steel booms, and cable, and the drag rakes are rigged in triplicate. The hauler method uses the lobster trap hauler and single rakes, rigged with rope. Approximately 20,000 MT of Chondrus in toto are harvested annually with these techniques. Studies carried out in 1975/1976 showed that up to 60% of the harvest by number consisted of immature fronds, and 25-35% of the fronds by number were attached to holdfasts. It was hypothesized that minor modifications to the drag rake such as modified tine spacings, elevated tines, and length and thickness of tines might reduce adverse ecological impact while improving fishing success.