The Reproductive Behaviour of the River Bullhead (Cottus Gobio L.), With Special Reference To the Fanning Activity
Abstract:The River Bullhead (Cottus gobio) is a common species of fresh-water fish in Britain, which forms a cavity-nest and protects and aerates its eggs. The nesting behaviour involves several forms of digging: mouth-digging, the carrying away of obstructions, pectoral fin digging, and tail-digging. During the reproductive cycle, the male spends most of its time lying inside the nest with its head at the entrance. In this position it catches its food, courts females, threatens rivals, aerates its eggs, and hides from predators. Apart from actual fighting, it may threaten rivals with a number of threat displays which consist of the following components: raising the gill-covers, lowering the head, opening the mouth, darkening the head, nodding, fin-raising, and undulating the body. The various displays consist of different combinations of the above components. Courtship consists of biting the head of the female, to which she responds sexually by entering the nest. Inside the nest the male and female assume a number of postures associated with the preparation for spawning. The eggs are laid on the roof of the nest. The female does not appear to assist in parental activities. The male fans the eggs with its pectoral fins, passing a current of water around the nest. It may construct an exit so that the current passes through the nest. When the young hatch they swim to the inside corners of the nest. The frequency of the fanning activity is measured throughout the parental cycle. This behaviour is compared with that of sticklebacks. The parental cycle lasts approximately four weeks, during which time the male fans almost incessantly. The fanning frequency increases and decreases mainly as a result of changes in the speed of the beating of the pectoral fins, and in this way it differs from the fanning of sticklebacks. The similarities and differences between the reproductive behaviour of the Bullhead and the sticklebacks is summarised. Fundamentally, they are similar in many ways. A brief review of the way in which different fish species assist in the development of their eggs is given.
Document Type: Research article
Publication date: 1955-01-01