Sustainability of shellfish stocks in the Irish Sea Essay

Sustainability of shellfish stocks in the Irish Sea - Essay Example The seminar presentation seeks to find ways that could help sustain the population of fish stocks in the Irish Sea. In order to achieve this, the organisms must be organized into different breeding groups, migration patterns; productivity, genetics and habitats must be first explored and understood. The shellfish were organized into a population structure whereby a population is a group of organisms of one species which can freely interbreed and live in the same place at a time (Atkinson, 2000)2. Populations can be further divided into sub-populations where interbreeding is restricted and the organisms accumulate genetic differences and may locally adapt to the environment. Another way of organizing the shellfish is by the use of the stock concept. This involves division into stocks for easier management. However, this may not accurately reflect genetic sub-division because in subdivision and productivity concept, each sub-population contributes absolute productivity to the total population which may vary depending on environmental conditions. While extirpation of subpopulations decreases, total productivity may increase vulnerability to environmental change and decrease genetic diversity. In considering subdivision and gene flow, the reduction in size or density of subpopulations may reduce migration between subpopulations and increases genetic drift or may increase migration into some subpopulations. Migration of locally harvested stock contribute to breeding populations over a much wider geographical area, for example, salmon and trout harvested in the ocean contain migrants from many different freshwater streams which are genetically isolated subpopulations and locally adapted to breeding streams (Nielsen, 1994)3. The methodologies used include the migration of larvae or adults between subpopulations, DNA extraction of haemolymph or muscle, DNA analysis through gene sequencing and screen for microsatellite markers used to measure genetic diversity. Another