Earth nutation influence on system dynamics of Northeast Arctic cod

Northeast Arctic cod in the Barents Sea is the largest stock of Gadus morhua cod in the world. The biomass of cod seems to have stationary cycles related to the Earth nutation. The present paper reports that current management of Northeast Arctic cod is not capable to handle these fluctuations and causes an unstable biomass. The total biomass needs a 15-20 yr planning perspective and it is suggested that the spawning stock biomass level is managed by a feedback control and the fluctuations of landings by a feed forward control.