Handley, S.H. (1997). Optimizing subtidal oyster production, Marlborough Sounds, New Zealand: spionid polychaete infestations, water depth, and spat stunting. Journal of Shellfish Research. 16(1): 143-150.

229710

Handley, S.H.

1997

16(1): 143-150

Publication

https://www.biodiversitylibrary.org/page/3450064

World Polychaeta Database (WPolyDb)

Four species of spionid polychaete of the genus Boccardia and three species of the genus Polydora were extracted from subtidal Pacific oysters using the vermifuge phenol and di-chlorobenzene, over a 15-mo study in Admiralty Bay, Marlborough Sounds, New Zealand. Shell blistering attributed to the burrowing activities of Boccardia knoxi infestations occurred over the second summer of growth after the hanging out of spat at the study sites in December 1993. The infestation period was consistent with a spring dispersive phase of B. knoxi larvae. After 13 mo of suspension, the proportion of oysters containing shell blisters was significantly greater at 6- to 12-m depth than near the water surface, which was attributed to the increased shell growth at the surface. Up to 57% of the oysters contained shell blisters, and 17% were unsuitable for the half-shell trade. In a separate experiment, oyster spat were subjected to increasing periods of intertidal storage or "hardening" in order to optimize growth rates and condition of subsequent subtidal cultivations. Spat were stunted by two methods: intertidal hardening and storage in a recirculating tank assumed to be food limited. Spat from each treatment were transferred to two growout sites in the Marlborough Sounds at monthly intervals over 9 mo. Spat stunting up to 9 mo had no significant effect on the minimum size of harvest within each site. After 9 mo of hardening, intertidally stunted spat grew significantly larger than spat stunted in a tank. Increased duration of stunting produced increased subtidal growth, with an almost doubling of growth rates between 1 and 10 mo of stunting. Stunting method or period had no significant effect on condition index or the derivative dry meat and dry shell weights at each site. Strong intersite differences in growth and condition were attributed to hydrodynamic factors. The progressive increase in growth rates with increasing stunting period indicated that the energy-compensatory and energy-conserving mechanisms developed intertidally by Crassostrea gigas spat increased with time. Because these adaptive mechanisms were also manifest in submerged spat fed on a limited diet, they appeared to be controlled by food limitation rather than by discontinuous feeding patterns present in the intertidal. An annual crop rotation is suggested for areas prone to B. knoxi, and spat stunting for optimal periods can be used to optimize subtidal growth and condition, thus reducing the growout time and avoiding fouling and spionid infestations.

New Zealand
Pacific, South West

Living resources, exploitation, fisheries
Parasites, Parasitism
Rearing (Aquariology, Aquaculture, Transport of living invertebrates)

Annelida
Polychaeta

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