Virtual Population Analysis (VPA) Equations for Nonhomogeneous Populations, and a Family of Approximations Including Improvements on Pope's Cohort Analysis
- 1 December 1986
- journal article
- research article
- Published by Canadian Science Publishing in Canadian Journal of Fisheries and Aquatic Sciences
- Vol. 43 (12) , 2406-2409
- https://doi.org/10.1139/f86-298
Abstract
A set of "backward" virtual population analysis (VPA) equations relates catch (Ct) from continuous fishing between times t and t + 1 to population n size (Nt, Nt+1) when a portion of the stock is unavailable to fishing. The usual VPA equations become a special case where the entire stock is available (i.e. the stock is homogeneous). A close approximation to the VPA equations is Nt = Nt+1 exp(M) + CtM/(1 − exp(−M)), which has properties similar to Pope's "cohort analysis" and is somewhat more accurate in the case of a continuous fishery, especially if the natural mortality rate (M) is large. Much closer simple approximations are possible if the seasonal pattern of catches is known.This publication has 4 references indexed in Scilit:
- A General Theory for Analysis of Catch and Effort DataCanadian Journal of Fisheries and Aquatic Sciences, 1985
- Algorithms for Solving the Catch Equation Forward and Backward in TimeCanadian Journal of Fisheries and Aquatic Sciences, 1982
- Review of the Rate of Growth and Mortality of Pacific Salmon in Salt Water, and Noncatch Mortality Caused by FishingJournal of the Fisheries Research Board of Canada, 1976
- A Solution of the Catch EquationJournal of the Fisheries Research Board of Canada, 1965