with the weight at age in the stock in the base year.
Harvest function allows for harvest to be directly proportional to both harvesting effort and stock biomass for both exponents equal to one. The stock exponent is reasonable if the stock is uniformly distributed in the sea. However, if a stock, such as mackerel, schools and can be subjected to directed fishing, a fall in stock biomass is likely to lead to a less than proportionate fall in harvest, implying.
the weight at age in the stock in the base year.
is reasonable if the stock is uniformly distributed in the sea. However, 
.