Fish Stocking and Population Dynamics in Freshwater and Marine Systems

Fish stocking is an extensively used technique for improving fish abundance and increasing the efficiency of fisheries production in both aquatic and marine environments. The study has reviewed the population-level effects of stocking, based on a variety of geographical regions, where different aspects that affect the effectiveness of stocking programs have been analyzed. Based on data from eight studies conducted in freshwater and marine environments, there was proof that both supplementation and enhancement programs contributed to an increase in population, whereby the average increase in freshwater environments was 28.4%, while increases in marine sites varied between 9% and 47% over a 24-month monitoring period. The density-dependent factors have constrained the effectiveness of stocking because it shows that an increase in stocking density by proportion does not always mean a population response will occur. Lentic freshwater systems showed the most effective responses, whereas marine systems were highly variable due to dispersal and environment heterogeneity during introduction and enhancement practices. The genetic compatibility of the stocked fishes and the resident fish communities had a direct positive correlation with the sustainability and recruitment of the populations. The results from this study show that both ecological, operation, and genetic aspects should be considered in stock enhancement programs. Future stocking methods should adopt an adaptive method whereby there is continuous monitoring, carrying capacity, and genetic screening. With the implementation of these strategies, stocking will ensure maximum benefit both ecologically and economically, and also increase population resilience.