Orange roughy is an important species in the South East Fishery (SEF).  The main areas in the SEF where orange roughy fishing has occurred are a major spawning aggregation off the east coast of Tasmania (the Eastern Management Zone) during winter and on non-spawning summer aggregations of the south coast of Tasmania (the Southern Management Zone).  Some data support separate stocks off eastern and southern Tasmania with an undetermined amount of mixing.  The current uncertainty in stock structure has important management implications, particularly on the size of the TAC that should be applied to the fishery.  The results of a previous study of orange roughy age composition in 1992/93 indicated that there were some differences in age composition between zones and there were indications of episodic recruitment. Analyses of otolith morphometrics indicated that there were significant differences between samples from the two areas.  However, because samples were taken during different seasons (i.e. winter and summer), interpretation of results was difficult.

 

This proposal was to repeat the earlier study and include samples from both areas during summer and winter.