Fish Population Restoration

      Dr. Wroblewski has been conducting research on a new method of marine fish population restoration, termed "enhancement of reproductive potential" or ERP (Wroblewski, et al., 1996; Wroblewski, et al., 1999; Wroblewski and Hiscock, 2002). This entails trapping late juvenile and young adult fish from the wild, increasing their growth and fecundity by feeding them in sea pens, and then returning the fish to their natural habitat to spawn. Hatchery based enhancement programs have met with criticism regarding genetic changes in cultured populations, and the fitness of released fish. Such criticisms do not apply to the ERP method. There is little or no impact on the genetic variability of the wild population since all fish, randomly collected from the wild, are released after captivity.
     This method of population restoration might be effectively applied in marine protected areas for many marine fish species whose potential fecundity is an increasing function of size. Dr. Wroblewski has been investigating the feasibility of increasing the spawning biomass in Newfoundland and Labrador bays with resident subpopulation of northern Atlantic cod. For example, Trinity Bay in eastern Newfoundland and Gilbert's Bay in southern Labrador both have a resident, genetically-identifiable, inshore-spawning subpopulation of Atlantic cod. The viability of fertilized eggs and larvae from farmed cod was demonstrated using the aquaculture facilities of the Ocean Sciences Centre at Memorial University (Wroblewski and Hiscock, 2002). In future research, Dr. Wroblewski will investigate the feasibility of increasing the reproductive potential of other species which are candidates for population restoration.

Fecundity of Atlantic cod treated by the ERP method versus fecundity of wild  Grand Banks cod (from Wroblewski, et al., 1999)


Wroblewski, J.S., Smedbol, R.K., Taggart, C.T., and Goddard, S.V. 1996. Movements of farmed and wild Atlantic cod (Gadus morhua) released in Trinity Bay, Newfoundland. Mar. Biol. 124: 619-627

Wroblewski, J.S., H.W. Hiscock and I.R. Bradbury. 1999.  Fecundity of Atlantic cod (Gadus morhua) farmed for stock enhancement in Newfoundland bays. Aquaculture 171: 163-180.

Wroblewski, J.S. and H.W. Hiscock. 2002.  Enhancing the reproductive potential of local populations of coastal Atlantic cod (Gadus morhua). Can J. Fish. Aquat. Res. 59: 1685-1695.

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