Evaluation of VPA estimates of population size of brown sole Pleuronectes herzensteini in northern Hokkaido, Japan
2006
Shimoda, K.(Hokkaido. Wakkanai Fisheries Experiment Station (Japan)) | ; Murooka, M. | ; Itaya, K. | ; Hoshino, N.
Evaluation of population size estimates from VPA (back calculation), VPA (forward calculation) and ADAPT VPA of brown sole Pleuronectes herzensteini population in northern Hokkaido, Japan was investigated by retrospective analysis. Relative error between population size by VPA based on eight years of fishing data and estimated population size by three methods of VPA based on one year of fishing data were -54 - +109% in VPA (back calculation), -41 - +59% in VPA (forward calculation) and -53 - +54% in ADAPT VPA. Relative error of age one by VPA (forward calculation) was the lowest of the three methods. At age three to six, relative errors by VPA (back calculation) and ADAPT VPA were lower than that of VPA (forward calculation). Relative errors of age two and seven showed no different between the methods. We tried to calculate the population size of age one to two by VPA (forward calculation) and over age three by VPA (back calculation). Relative error by the new method was -26 - +5%.
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