Treatment of spionid mud worm (Boccardia knoxi Rainer) infestation of cultured abalone

Early attempts at sea cage culture of blacklip abalone (Haliotis rubra Leach) in southern Tasmania, Australia were characterised by infestation with spionid polychaetes, commonly Boccardia knoxi. Large numbers of mud worms were associated with severe blistering and stock mortality. Immersion treatment using chemotherapeutics and air-drying treatment was tested for efficacy in eliminating mud worms and lethality to abalone. Air drying of spionid-infested abalone for 2-4 h at <64% humidity significantly reduced infestation levels of two species of spionid polychaetes. Such treatment produced no abalone mortality in the short term, and 100% of 40 mm H. rubra dried for 11 h survived a 54-day posttreatment observation period. Treatment air drying suppressed abalone growth in the long term in one of three trials. Such treatment is considered worthwhile in cases of heavy spionid infestation. © 2003 Elsevier Science B.V. All rights reserved.