The Sea Garfish, Reporhamphus melanochir (Cuvier & Valenciennes) (Hemi-ramphidae), in South Australia: Breeding, Age Determination, and Growth Rate

Abstract

There are seven macroscopic gonad stages recognizable in male sea garfish. and eight in females with which ova diameter measurements have been correlated . In South Australia the spawning period lasts from late September to early March. and activity is most intense during October and November . A second period of breeding activity may occur in February . A few females are sexually mature at 2 years. but the majority do not spawn for the first time until the end of 3 years .This applies also to males. A latent maturation cycle is demonstrated in immature female garfish.

The use of otoliths for age determination is described and the method validated by Petersen length frequency polygons. The rate of growth has been deduced from calculated intermediate lengths of younger garfish, based on an otolith lengthlfish length relation and the mean lengths of older age groups. The weight of the garfish varies as the cube of the length. Females attain a larger average size than males after the third pear. Gulf St. Vincent females grow faster than those in other regions; males, however, are variable.

Application of these results to a management policy for the commercial fishery is severely restricted by the inadequate official catch statistics. However, it is recommended that netting of garfish in Coffin's Bay be prohibited, but that no change in the minimum legal length should be made for the present.