Applying CPUE as management tool a discussion

CPUE as management tool Outline Introduction Context of CPUE Merit of CPUE indicators CPUE and the Dutch beam trawl Debate topics

CPUE as management tool Introduction C = f q B (1) U = C/f (2) U = q B (3) C t/f t= α(C t+1/f t+1) (4) q tN t = α (q t+1N t+1) (5)

CPUE as management tool Context of CPUE Different CPUE measures Catch: Kg, $ Effort: Hp, seadays, $ Stock — CPUE CPUE > minimum insight CPUE development

CPUE as management tool Merit of CPUE indicators Catch in kg Proceeds in monetary terms Hp-days Costs per time unit Energy usage per unit of time

CPUE as management tool CPUE and the Dutch beam trawl fisheries

CPUE as management tool CPUE and the Dutch beam trawl fisheries Correlation coefficient between selected CPUE measures and stock levels

CPUE as management tool Debate topics Relationship CPUE — Stock Simple indicator Time aspect CPUEt , Stockt-1, sole , Stockt-2, plaice , Multi-species fisheries Catchability coefficient q Effort allocation Conclusions Issues

CPUE as management tool CPUE is a relative simple indicator which can be established ‘above the water’. With modern technology monitoring in ‘real time’ could be established. By using CPUE the motivation for underreporting catches and manipulating catch declarations is reduced. The information is derived from the commercial fleet itself which enhances the dialogue between the industry and the policymakers. Closing remarks