CONDITION OF LARVAL WALLEYE POLLOCK, THERAGRA-CHALCOGRAMMA, IN THE WESTERN GULF OF ALASKA ASSESSED WITH HISTOLOGICAL AND SHRINKAGE INDEXES

Condition of field-caught walleye pollock, Theragra chalcogramma, larv ae was assessed by using a measurement of midgut cell height that reli ably diagnosed the nutritional status of laboratory-reared walleye pol lock. The midgut cell height was simple to measure on histological sec tions. Several correction factors were developed for applying the midg ut measurement to a field study. These included regressions to charact erize change in larval length associated with net collections of vario us elapsed times and with fixation in several types of preservatives. The response of midgut cell height to field collection procedures also was tested. The field study indicated larval walleye pollock were sta rving in the Shelikof Strait, Gulf of Alaska, in 1991. At some station s up to 40% of the larvae were in poor condition. Larvae were most vul nerable to starvation for 2 weeks following the day of first-feeding.