Language selection

Search

Research Document - 2000/087

Metapopulation theory and northern cod population structure: interdependency of subpopulations in recovery of a groundfish population.

By P.K. Smedbol and J.S. Wroblewski

Abstract

Atlantic cod (Gadus morhua) population inhabiting the coastal and offshore regions of eastern Newfoundland and Labrador. Evidence for subpopulation structure is drawn from studies of spawning time and locations, morphometrics, and genetic differentiation. We identify putative subpopulations associated with spawning areas near offshore banks and in coastal bays. The historical northern cod population is first represented as an unfished metapopulation. We then modify the model to include the influence of fishing harvest on subpopulation extinction. Metapopulation theory predicts that fewer spawning areas are occupied as the population declines. This prediction is validated in that Saglek, Nain, Makkovik and Harrison Banks have had no significant spawning activity since the over exploitation by trawlers during the 1960s. The corollary prediction is that as the population recovers, currently unoccupied spawning areas will be recolonized. The model suggests a continued moratorium on fishing the remaining subpopulations would promote recolonization and accelerate the recovery of the overall metapopulation.

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.

Date modified: