1. Applying CPUE as management tool a discussion

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

3. 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)

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

5. 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

6. CPUE as management tool
CPUE and the Dutch beam trawl fisheries

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

8. 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

9. 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