Reproductive Behavior of Pacific Cod in Captivity

Abstract

The reproductive behavior of Pacific cod (Gadus macrocephalus) was examined during captive experiments. The captive cod spawned demersal and slightly adhesive eggs, which dispersed and settled on the tank bottom. Ripe males and females did not display the ventral mounting behavior typically displayed in other gadid fishes during spawning. Neither sound production nor aggressive behavior occurred during the breeding period. The female released approximately all of her ripe eggs in a single spawning, which lasted less than 20 seconds. Spawning involved one female and one or more males in midwater of the tank. Just after release of eggs by a female, one or a few males followed the female and spread sperm on the eggs using tail beats. The eggs and milt slowly sank to the bottom. The spawning behavior of Pacific cod differed from the single-pair spawning characterized by ventral mounting and multiple spawning over a several day period seen in walleye pollock and Atlantic gadid species.