Fish Population Dynamic and Stock Assessment

6.5.2 Recruitment

The process by which a fish or shrimp of an age groups integrates itself for the first time in to the exploitable stock is known as recruitment, which is a function of age and is a progressive event. The animals added on to the population is called the recruits.

The concept of stock recruitment relationship is related to the concept of surplus production. It is a general concept their when population becomes smaller, the reproduce success increases. The following are the mechanisms by which the reproductive success of a fish can increase.

i) Increased growth and better fecundity of a species.

ii) Good food supply / individual

iii) Good survival of eggs and larvae due to reduced cannibalision.

iv) Optimal fishing effort.

The recruitment pattern is affected by environment variables. When the environment variables are at optimal level, relationship between stock and recruitment will be accurate.

Three models are used

1. Ricker bell shaped curve model

2. Beverton and Holt model

3. Cushing model