Metapopulation theory and northern cod population structure : interdependency of subpopulations in recovery of a groundfish population / R. Kent Smedbol and J.S. Wroblewski. : Fs70-1/2000-087E-PDF

This report examines the Atlantic cod 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. Putative subpopulations associated with spawning areas near offshore banks and in coastal bays are identified. The historical northern cod population is first represented as an unfished metapopulation. The model is then modified 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.

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