Tag recapture studies of the chokka squid Loligo vulgaris reynaudii d′Orbigny, 1845 on inshore spawning grounds on the south-east coast of South Africa

Abstract

To study their migratory movements, Chokka squid ( Loligo vulgaris reynaudii) were tagged on their inshore spawning grounds in early summer: 1748 in November 1992 and 4335 in November 1993. Squids were captured by hand jigging in depths of 24–35 m. Diving observations revealed that the behaviour pattern of recently tagged individuals was similar to that of untagged squid on the spawning grounds. Recaptures from commercial jigging vessels subsequent to tagging were 33 (1.89%) in 1992 and 387 (9.04%) in 1993. The longest tag-recapture duration was 32 days. Loligo. v. reynaudii moved to other spawning sites within the general spawning area, up to 207 km within 18 days. In 1993, mean speed was calculated as 3.0 km/day and mean distance travelled 42.8 km in a mean time of 14 days. Squids dispersed predominantly eastward from those tagged on the westward limit of their inshore spawning grounds. Those tagged towards the centre appeared to move randomly between spawning sites, possibly influenced by environmental conditions and food availability. Loligo v. reynaudii may be considered an uniseasonal-iteroparous species, maximising their reproductive potential by depositing eggs over an extended period in a number of spawning sites.