• The fluctuation of year-classes and the regulation of fisheries 

      Cushing, David H. (Fiskeridirektoratets skrifter, Serie Havundersøkelser, Research report, 1969)
      There are three sources of variation of recruitment; first that due to random fluctuations alone, secondly that, due to variations in stock and thirdly variations which are extreme at low and high levels of stock and if ...