Beverton and Holt's Yield per Recruit Model
![]() The Beverton and Holt yield per recruitment model is utilizing the individual growth model of von Bertalanffy and the Baranov mortality model. Baranov describes mortality as a continuous process in time where the number of individuals is monotonously reduced from the initial number (number of recruits) and a fixed mortality rate ( ). The number of individuals at time then is .The marginal mortality rate ( ) may be decomposed into a natural component ( ) and mortality caused by fishing ( ), . is a control variable in fisheries; when not fishing, , while increases as the fishing effort is increased.Another control variable in fisheries is related to how large the targeted fish is, namely the age of the fish when caught, labeled (age of first catch). Usually (as in this Demonstration) this is the age of a sudden shift in marginal mortality rate from to , often referred to as knife-sharp selection.![]() "Beverton and Holt's Yield per Recruit Model" from The Wolfram Demonstrations Project http://demonstrations.wolfram.com/BevertonAndHoltsYieldPerRecruitModel/ Contributed by: Arne Eide | ||||||||||||||
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