Age and growth of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in Queensland east-coast waters with implications for stock structure

Abstract

Age and growth of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in east-coast waters, Queensland, Australia (16˚S to 28˚S), were determined to provide population parameters required for stock assessment and fisheries management. Female school mackerel (L_∞ = 651 mm, K = 0.59, t₀ = –1.41) were estimated to grow to a greater asymptotic length, but at a slower rate, than males (L_∞ = 628 mm, K = 0.71, t₀ = –1.26). Growth patterns of school mackerel differed between geographic regions and suggested the existence of separate stocks throughout the east-coast distribution. In contrast, female spotted mackerel (L_∞ = 849 mm, K = 0.46, t₀ = –1.54) were estimated to reach a greater asymptotic length at a faster rate than males (L_∞ = 768 mm, K = 0.23, t₀ = –4.33). There was no difference in growth between spotted mackerel from different regions, suggesting that there is a single stock along the Queensland east coast. Identification of school and spotted mackerel populations in Queensland east-coast waters will enable the species to be managed on the basis of stock structure across this range.