Theoretical assessment of the impact of seeding on the exploitation of some economically viable marine populations
Many rural communities in the developing world practice small-scale harvesting of marine species of various kinds (fish, crustaceans, mollusks) as their main economic activity. Lack of regulation or enforcement or both has led in many cases to overexploitation of resources and consequent decline of the populations of organisms on which the communities depend. This situation, common along the north-central Chilean coast, served as the starting point of the present work. Recent advances in biotechnology and aquaculture, however, have made plausible halting or even reversing the trend towards resource depletion, favorably affecting the economic well-being of the communities. In this paper the theoretical implications of seeding the habitual harvesting grounds of a hypothetical community with individuals produced in the laboratory is explored. In particular, we examine the effect of periodic seeding of hatchlings or juveniles on the population of an economically important species harvested under either one of two modes of extraction, constant harvest or harvest proportional to the stock level. The population dynamics is modeled by a first order ordinary differential equation containing a series of delta functions, and which in words reads as follows: the population growth rate is equal to the natural growth rate minus the harvest rate plus the seeding rate. It was found that, at least from a theoretical standpoint, seeding could potentially lead to a notable increase in the productivity and well-being of these sea-based economies.