Question

What is the relationship between biomass at Maximum Economic Yield (MEY) and those at Maximum Sustainable Yield (MSY) and Bio-economic Equilibrium (BE)? Give an equation for the said relationship.

Answer 1

Maximum Economic Yield is that yield level, which coincides with the level of harvest or effort that maximised that sustainable net returns from fishing. MEY is a long -run equilirium concept which refers to the level of output and the corresponding level of effort that maximise the expected economic profits in a fishery.

Sustainable yield means ' the development which meets the needs of the present without compromising the ability of future generations to meet their own needs'. Sustanable Yield [SY] can be caculated as the idea that a "crop" can be taken from an ecosystem in a way that leaves the ecosystem viable for the future.

SY=[  Total biomass   * time t +   1 ] - [Total biomass * time t ]

Energy Energy

The model works on the idea that as long as there are more new members of a population at the end of the year than at the begining it is possible to exploit the extra without harming the population.

Maximum Sustainable Yield (MSY) is the largest yield that can be taken from a speices stock over an indefinite period.

• The Maximum Sustainable Yield (MSY) is uaually higher than the Optimum Sustainable Yield and Maximum Economic Yield.

Bio -Economic Equilibrium means an equilibrium that combines the biological mechanics with economic activity.

In Gordon- Schaefer model, it is assumed that price of fish and cost of unit effort is constant so that the total cost and revenue lines vary in proportion with the effort and catch respectively.