MORTALITY OF SCALLOP SPAT IN CULTIVATION, INFESTED WITH TUBE DWELLING BRISTLE WORMS, POLYDORA SP.

S. Mortensen, T. Meeren, A. Fosshagen, I. Hernar, L. Harkestad, L. Torkildsen, Ø. Bergh-2000
Aquaculture International, 8 (2/3): 267-271

Abstract:
Between 1995 and 1997, a traditional Norwegian oyster poll with an attached nursery was used for the production of scallop (Pecten maximus) spat. During summer 1997, four batches of 2 mm scallop spat were placed in the nursery. In June, hydroids (Obelia) caused problems with fouling and accumulation of sediment in the nursery. Thereafter, the scallop spat were heavily infested with tube dwelling polychaets (Polydora sp.). The polychaets were both introduced with poll water and reproduced inside the nursery. Infested spat suffered high mortalities. Although the spat could have been affected by the hydroids, as well as shortage of food, Polydora infestations were considered the main cause of the mortalities. Dead and infested spat were continuously sorted out and discarded, but the infestation problems persisted. As a result, the scallop spat did not represent any commercial value for the company, and in September the nursery was emptied. In total, approximately one million spat - representing one third of Norway's intensive scallop spat production in 1997, was lost.

(Institute of Marine Research, Department of Aquaculture, PO. Box 1870, Nordnes, 5817 Bergen, Norway, tel: (47) 55 23 63 69; fax: (47) 55 23 63 79; E-mail: stein.mortensen@imr.no)

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