THE USE OF PLASMA PARAMETERS TO PREDICT OVARIAN MATURATION STAGE IN ENGLISH SOLE PAROPHRYS-VETULUS GIRARD

Oocyte development and associated changes in condition factor and levels of estradiol, vitellogenin [measured as alkali-labile protein-associated phosphate (ALP)], calcium, magnesium, phosphate, total protein, triglycerides, and glucose in plasma were monitored in female English sole Parophrys vetulus Girard from Puget Sound throughout the 1985-86 and 1986-87 spawning seasons. Discriminant analysis was applied to data collected in 1985-86 to select a suite of parameters that could accurately differentiate between female sole in different stages of ovarian maturation. On the basis of plasma levels of ALP, estradiol, total protein, and triglycerides, fish in five histologically determined ovarian maturation stages (i.e., regressed, previtellogenic, vitellogenic, spawning, and spawned out) could be distinguished from each other with almost-equal-to 70% accuracy. When the model was used to classify female sole collected in 1986-87, ovarian maturation stage was predicted correctly in 68% of the fish examined, a significantly greater proportion than the 20% which would be expected on the basis of chance alone. This method for predicting ovarian developmental stage would be particularly useful in laboratory studies in which it is necessary to assess the stage of gonadal development without sacrificing test animals, and could also be applicable in field studies designed to monitor reproductive cycles of marine species.