# Produktfunksjoner

Production of harvest (*H*) is a production process involving two essential production factors, fishing effort (*E*, which itself could be produced in a number of different ways) and stock biomass (*X*, which in the short run is given).

The figure shows the long term relationships in terms of long term catch (red curve on top) and long term stock-effort relationship (red line below). The green curve gives the natural stock biomass growth as a function of stock biomass (*F(X)*), while the blue lines represent short term catches of different constant fishing effort values (*H(E=const.,X)*).

The conversion from the short term catch equation to the long term catch equation is obtained by implementing the long term effect on the stock biomass from fishing effort:

Open and free access to a fishery implies that one of the production factors (*X*, the stock biomass) is freely available even if this is a scarce resource. This is a basic market failure. Another characteristic with a fishery, including an open access fishery, is the long term consequences of previous fishing activities, which implies a relationship between the two input factors. In the long run the stock biomass may be determined by previous use of fishing effort.

**Explore the relation between short term and long term harvest functions in the demonstration to the left.**

More on the production function in fishery could be found here: http://en.wikibooks.org/wiki/Bioeconomics