Movements and stock structure of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in Australian east-coast waters

Abstract

Movements of school mackerel (Scomberomorus queenslandicus) and spotted mackerel (S. munroi) in Australian east-coast waters were determined by tag and recapture methods and were used to investigate the stock structure of each species. In all, 4427 school mackerel and 2106 spotted mackerel were tagged and released between 1985 and 1995 in a collaborative tagging exercise with the Australian National Sportfishing Association. School and spotted mackerel were recaptured at rates of 2.1% and 1.8% respectively. School mackerel moved small distances from their release sites (26 ± 55 km, mean ± s.d.; maximum distance, 270 km), with these restricted movements indicating the possible existence of a number of stocks. In contrast, spotted mackerel moved large distances from their release sites (202 ± 290 km; maximum distance, 1100 km). Temporal and spatial movement patterns of spotted mackerel were characteristic of fish from a single stock undertaking a seasonal migration. Commercial harvest information in combination with tagging effort reflected the different movements of school and spotted mackerel and strengthened the suggested stock structure of each species.