Use of the sea urchin Hemicentrotus pulcherrimus for biological control of fouling in suspended scallop cultivation in Northern China

• Survival of scallop and sea urchins co-cultured in lantern nets is very high.
• Sea urchin reduced fouling on scallop net and on P. yessoensis shell.
• Greater growth in scallop soft tissue was associated with sea urchin.
• Sea urchin co-cultured with scallop can provide an additional valuable crop.

Fouling organisms on scallop cultivation nets and shells are costly to remove and can reduce scallop growth. In the present study, we investigated the biological control efficiency of using the sea urchin Hemicentrotus pulcherrimus as a means of preventing fouling in suspended scallop cultivation of Chlamys farreri and Patinopecten yessoensis in Sanggou Bay, Northern China. Tests were carried out from June to September 2009, during the period of the heaviest fouling. The scallops were co-cultured in scallop lantern nets for 3 months. At the end of the experiment, all sea urchins were alive and the survival rates of scallops were very high. Scallop shell length and soft tissue growth were not significantly affected by sea urchins, but a greater growth in scallop soft tissue was associated with the presence of the sea urchin. Sea urchin had a minimal effect on the shell fouling of C. farreri, but noticeably reduced the weight of fouling on scallop nets and efficiently reduced fouling on the shell of P. yessoensis. Results suggest that the sea urchin was an effective biological control organism, especially for the shell fouling of P. yessoensis. This experiment indicated that biological control, using sea urchin, of fouling in suspended scallop cultivation has the potential to become an efficient and environmentally-sound method for addressing the problem of fouling in scallop cultivation.