1. Longline CPUE standardization: IATTC 2006
Simon Hoyle and Mark Maunder

2. Introduction Longline fisheries Indices of abundance
Statistical methods
Results & discussion
Model selection
Diagnostics
CPUE indices
Compare with last year
Parameter estimates

3. Longline fisheries
Northern
Southern

4. Indices of abundance
Standardized CPUE assumed proportional to abundance
Japanese longline data, 1975 – 2004
Provided by SPC
Catch in numbers, effort in hooks
Methods
2005 – delta gamma GLM
– neural networks
– regression trees

5. Statistical methods Strata defined as 5º square / HBF category
Only strata with at least 5 non-zero catches are included
Delta lognormal model
w = g(Year.qtr, Lat.Long, HBF, effort)
f(y) = h(Year.qtr, Lat.Long, HBF)

6. Change from last year In 2005
Used delta gamma model
Didn’t include effort in delta component of GLM
Delta lognormal fit the data better (AIC)
Change makes very little difference to results

7. Catch and effort (northern)

8. Catch and effort (southern)

9. Un-standardized data – proportion zero & nonzero CPUE

10. Model selection

11. Residuals for non-zero component through time

12. Residuals for non-zero component

13. Standardized CPUE - bigeye

14. Standardized CPUE - yellowfin

15. Raw vs standardized CPUE

16. Standardized CPUE / CPUE standardized by time only
slope= ±

17. Standardized CPUE / CPUE standardized by time only
slope = ± 003

18. Average HBF through time

19. HBF parameters

20. Bigeye south

21. Yellowfin south