Physiological basis of inter-population, inter-familiar and intra-familiar differences in growth rate in the green-lipped mussel Perna canaliculus

In New Zealand, three quarters (by value) of national aquaculture exports are based on the production of an endemic species, the green-lipped mussel, Perna canaliculus, yet there remains a paucity of information describing its underpinning biology. The majority of seed stock is still derived from wild capture from two main geographic locations, however commercial hatchery production has just begun. An established selective breeding programme, now in its 7th generation, has created family lines selected for desirable production traits, including growth rate. The current study therefore used animals derived from selectively bred lines, as well as animals produced in the hatchery from the two geographically distant populations used for commercial spat-catching, which are observed to have differences in growth rates, to explore the key energetic and morphological parameters that may determine fast and slow growth and growth efficiency. Metabolic rates, clearance and assimilation parameters, and morphological characteristics were established for mussels from 3 distinct levels of relatedness; comparing populations, full sib families (selected a priori for fast or slow growth rate), and inter-individual differences between siblings within families displaying heterogeneous growth rates.