Assessment of gonad staging systems and other methods used in the study of the reproductive biology of narrow-barred Spanish mackerel, Scomberomorus commerson, in Western Australia - the Department of Fisheries Research Reports produced by the Department of Fisheries

Recent research by the Department of Fisheries in Western Australia into the reproductive biology of narrow-barred Spanish mackerel has required the use of various field and laboratory techniques. This report documents the procedures and adaptations of some of these techniques. Assessment and development of illustrated, relevant macroscopic and microscopic staging systems were of particular focus because both have been essential components of the research. The simplified and more reliable macroscopic staging system we developed allowed full use of all gonad samples and a more complete (albeit less distinct) overview of the seasonal pattern of gonad reproductive development. This macroscopic staging system will be useful for ongoing, low budget monitoring of Spanish mackerel stocks in Western Australia. More detailed and accurate (but less complete) data were provided by the microscopic staging system, allowing specific information about spawning and other reproductive characteristics of this species. Methods used in the collection and processing of samples and in the estimation of batch fecundity of females are also documented along with conversion factors between weights of fresh, frozen and formalin-fixed gonads.