Biology of the Dragonet, Callionymus kaianus moretonensis Johnson (Pisces: Callionymidae)

Abstract

A collection in excess of 1000 specimens of Callionymus kaianus moretonensis, trawled off southern Queensland, afforded an opportunity to study various aspects of the biology of this species. It inhabits muddy bottoms at depths of 101–150 m off south-east Queensland between Noosa and Cape Moreton, Moreton Island. Penaeid prawns were the predominant food during all seasons and for all size groups. A great diversity of food items were ingested, especially in the pelecypod and gastropod categories. Factors influencing feeding and vulnerability of prey organisms are discussed. Of the 907 specimens that were sexed, 422 (46.7%) were males and 485 (53.3%) were females. C. k. moretonensis has a prolonged breeding period in which each female spawns a number of times. Only a few oocytes appear to be discharged at any one time from the ovary. Practically every stage of ovarian development was found in each ovary examined regardless of time of year. Oocyte diameter averaged 0.51 mm immediately prior to spawning and numbers of ova ranged from 1285 to 22,478. C. k. moretonensis may have either a benthic larvae or a short-lived planktonic one. Length-weight relationships are represented by the regressions, log W = -1 5.24 + 3.77 log L (males) and log W = -16.77 + 4.12 log L (females). Otoliths were used for age and growth determinations. C. k. moretonensis reaches age group IV+. Growth of males slightly exceeded that of females, with the greatest difference occurring between the third and fourth years of life. No evidence of high post-breeding mortality was found in spent males.