Effects of genetic and environmental factors on growth of southern calamary, Sepioteuthis australis, from southern Australia and northern New Zealand

Abstract

Extreme plasticity in growth is consistently found by ageing studies on squid. This study examined the contribution that genetic and environmental factors had on growth of the southern calamary, Sepioteuthis australis, from sites in southern Western Australia, South Australia and New Zealand. A total of 147 adults, comprising three sympatric genetic types (two parental taxa and one hybrid), were aged by counting microincrements in statoliths. Estimates of age ranged from 121 to 268 days and varied with mantle length, sex, genetic type and region. Males grew much faster and attained a larger size than females. Significant differences were also detected between genetic types, with the hybrids always growing faster (at least 60% larger at 150 days old) than the two parental taxa, a phenomenon commonly referred to as hybrid vigour. Spatial differences in growth were also detected, with individuals from Western Australia usually growing faster than those from South Australia and New Zealand. Possible explanations for these growth patterns are discussed.