The reproductive biology of Solea bleekeri (Teleostei) in Lake St Lucia on the south-east coast of Africa

Abstract

Solea bleekeri occurs throughout the predominantly muddy and highly turbid Lake St Lucia, with juveniles and adults being present throughout the year. Evidence is presented to support the hypothesis that S. bleekeri breeds in specific parts of the lake and that spawning takes place between September and December following a southward migration of reproductively active fish. The data suggest that S. bleekeri is able to vary its reproductive strategy. Under normal circumstances, the species migrates from the system to spawn at sea during winter along with other marine fish species which spend part of their life cycle in estuaries. However, when conditions within the lake are suitable, a part of the population will remain and breed there. Recruitment of S. bleekeri into the St Lucia estuarine system takes place from the muddy offshore marine banks, probably via surf zone nursery areas, as well as from within the system. There are indications that, in some years, post-spawners move back up the lake en masse, whereas in other years there is simply a gradual movement of fish.