Variation in Dispersal of Galjoen (Coracinus capensis) (Teleostei: Coracinidae) from a Marine Reserve

Abstract

The dispersal of the surf-zone teleost galjoen (Coracinus capensis) from the De Hoop Marine Reserve, South Africa, was investigated. Over a period of 5.5 yr, 11 022 galjoen were tagged in the centre of the reserve. Most of the 1008 recoveries were at the site of release, while the remainder covered a distance of up to 1040 km. There was no difference with respect to age, sex, or season between those that dispersed and those that did not. Six models were developed to test the hypotheses that (1) galjoen are polymorphic with respect to dispersal behaviour, (2) nonreporting of tags masks a random dispersal process, and (3) the recovery distribution is the result of unequal movement rates in different areas. It is inferred from the likelihoods of the various models that the tagged population was polymorphic, with fish displaying either resident or nomadic behaviour. This conclusion is unaffected by a large uncertainty in the extent of nonreporting of recoveries, or by spatial variability of movement rates. The estimate of emigration from the reserve implies that the unharvested reserve population is restocking adjacent exploited areas with adult fish.