A nutrient to fish model for the example of the Baltic Sea

Examples of experimental runs over 40 years are discussed: A baseline simulation gives an approximate hindcast scenario of stock variations and catches over the time period of the years from 1963 to 2003 with increasing and declining cod catches. As known from observations, the stock size of sprat shows a reverse trend, while the herring stock appears to be relatively stable. The modeled results display several observed features, e.g. stock sizes and magnitude of changes, but the response times and phases of the variations are not well reproduced. Moreover, scenarios are simulated to indicate how moderate adjustments of fishing rates of cod over different time periods would change the stock and catches.