Evaluating growth of larval walleye pollock, Theragra chalcogramma, using cell cycle analysis

Cell cycle analysis of muscle cell division rates offers a new and efficien t technique to analyze growth of larval fish. Using this approach, growth o f larval walleye pollock was estimated by determining cell proliferation ra tes, reasoning that growth during early life stages is probably attributed to increases in cell number rather than to increases in cell size. Characte ristic patterns of brain and muscle cell division rates were produced in la rval walleye pollock by manipulating their diet in the laboratory. The frac tion of dividing muscle cells and, to a lesser extent, the fraction of divi ding brain cells were direct indicators of fast and slow growth. A model wa s produced to estimate average growth rate from the fraction of dividing mu scle cells. We developed a simple method for preparing and storing the musc le tissue that ensures nucleic acid stability for subsequent analyses and p ermits sampling in the field. We envision that the cell cycle methodology w ill have on-site applications, presenting an opportunity to attain real-tim e estimates of larval fish growth at sea. Determining the proportion of fir st-feeding larvae with a high fraction of dividing muscle cells may yield a means for predicting the proportion of fast-growing fish, i.e., the potent ial survivors.