The biology of the soldier fish, Gymnapistes marmoratus (Pisces: Scorpaenidae)

Abstract

Various aspects of the biology of the scorpaenid Gymnapistes marmoratus were studied during 1971 in the D'Entrecasteaux Channel, southern Tasmania. The species ranges from Darwin counter-clockwise around the Australian coast to Sydney, but appears not to inhabit Queensland waters. In Tasmania the species commonly occurs at depths of 20 m or less, over sand or mud bottom with a light Zostera covering. During the day the fish lie motionless and are excellently camouflaged, possessing disruptive yellow and brown marbled markings; most of their activity occurs at night. Fish species associated with G. marmoratus are those typical of the bottom habitat of estuarine communities. Age determination by interpretation of annuli in burned otoliths was found to be simple and accurate, and the population studied comprised individuals up to 14 years of age. Growth was adequately described by the von Bertalanffy equation of organic growth, being of the decaying exponential type which defined the growth of G. rnarmoratus as:

L_t = 21.4[1-exp{0.1168 ( t + 2 . 3 )}].

Reproduction is initiated at approximately 2 years of age and spawning occurred in August-September. Fecundity may be described related to length by the expression F = 0.08L^4.08. Stomach analysis indicated that shrimps and crabs made up a large portion of the diet of smaller fish, while the larger fish consumed other fish species as well.