The reproductive biology of a shallow water morid ( Salilota australis Günther, 1878), around the Falkland Islands

Abstract

The reproductive biology of a shelf morid, red cod ( Salilota australis) was investigated in the Falkland Islands, in order to expand our knowledge of the reproductive strategy of this relatively unstudied family of fishes. Red cod spawn to the south and south-west of West Falkland between August and October. Length frequency and sex ratio data suggest that females arrive at the spawning grounds first. The greatest spawning activity occurred in early evening and this timing may be an adaptation to reduce predation on eggs. Ripe egg size varied from 0.95 to 1.26 mm and was not dependant on female size. There was no regulative atresia during maturation and the formation of fecundity and fecundity increased with increasing fish total length ( L T) from 300,000 (42–45 cm L T) to 4.5–9.0 million eggs (75–83 cm L T). The fecundity of most of the population was between 2 and 5 million eggs. Red cod releases small batches of eggs over the spawning period. Batch size ranged from 30,000–90,000 (39–42 cm L T) in smaller animals to 400,000–800,000 (>75 cm L T) in larger animals and the batch size of first spawners was significantly higher than for advanced spawners. The study allows us to discuss the evolutionary relationships between the Gadiformes.