Visual assessment of the reproductive condition of female western rock lobsters (Panulirus cygnus)

An important issue when surveying the reproductive condition of large numbers of female Panulirus cygnus in the field is that each animal must be assessed quickly and accurately on the basis of only a few easily discernable criteria. The four biological criteria most commonly recorded for each lobster are: (1) ovigerous setae condition (not present, partially developed, and fully developed); (2) the presence (unused or eroded) of a spermatophore mass; (3) the presence and developmental stage of external ova; and (4) the visual appearance of the ovaries through the dorso-thoracic musculature. Using the above criteria each female can then be assigned to a reproductive state, i.e., immature, inactive breeder, single breeder, or double breeder. This study compared external assessments with internal cellular development of the ovary (via histology) and elucidated the shortcomings of the external technique. This has resulted in the production of a modified set of criteria that, if applied to samples collected during the peak of the breeding season, enables the breeding state of a female western rock lobster to be more accurately determined in the field without causing it any damage. The height of the breeding season is the optimum time for stock egg production assessment.