Publication Abstract

Spatfalls of the non-native Pacific oyster, Crassostrea gigas, in British waters

B.E. Spencer, D.B. Edwards, M. Kaiser and C.A. Richardson

Light spatfalls of the Pacific oyster, Crassostrea gigas, have occurred in the estuaries of the Rivers Exe, Teign and Dart (Devon) and in the Menai Strait (Gwynedd), near to sites of commercial cultivation of this species. Comparisons of the sizes of the naturally settled oysters with hatchery oysters suggests that the spat from the River Teign and Menai Strait settled in 1989 and 1990. The springs and summers of these years were exceptionally warm with mean monthly air temperatures 0.8 degree -1.3°C above the 1951-1980 average for the period April to August. Although sitings of Pacific oyster spat were made in Loch Sween and Emsworth Harbour over 20 years ago, there is no evidence that self-sustaining populations have developed. The spatfalls which occurred in some coastal waters of Devon and Gwynedd in 1989 and 1990 are unlikely to sustain natural fisheries and are likely to die out as did the Portuguese oysters which occasionally settled in the River Blackwater, Essex.

Reference:

B.E. Spencer, D.B. Edwards, M. Kaiser and C.A. Richardson, 1994. Spatfalls of the non-native Pacific oyster, Crassostrea gigas, in British waters. Aquatic Conservation Marine and Freshwater Ecosystems, 4(3): 203-217