The effects of size-selective feeding by starfish ( Asterias vulgaris) on the production of mussels ( Mytilus edulis) cultured on nets

Laboratory feeding trials were conducted in which excess rations of four different size classes of mussels were provided to three different size classes of starfish. Although differences in size-selective feeding behaviour occurred between different size classes of starfish feeding separately and those feeding aggregately, the total food intake remained the same. The consumption of mussel meat by starfish based on the relative ash-free dry weights of both prey and predator ranged from 6 to 8.6% day −1. Patterns of size-selective feeding behaviour and feeding rates of starfish observed in the laboratory appear consistent with the changes in relative abundance among year class cohorts of mussels and starfish residing on culture nets at a mussel farm. It is concluded that the impact of starfish predation at the mussel farm is not likely to affect adversely the marketable yield of older mussels, and may provide a beneficial influence through the culling of undersized mussels.