INTERPRETING PACIFIC HALIBUT CATCH STATISTICS IN THE BRITISH-COLUMBIAINDIVIDUAL QUOTA PROGRAM

An individual quota management program was implemented on Pacific hali but (Hippoglossus stenolepis) in Canada in 1991. Subsequent changes in fleet behavior influenced the interpretability of catch-per-unit-effo rt (CPUE) statistics. A regression analysis on Pacific halibut CPUE st atistics collected from 1986 to 1994 indicates that year, season, area , vessel class, and gear type all significantly influence CPUE and tha t there are significant year x season, year x area, and other interact ions. CPUE as an annual index of abundance appears to be influenced by changes in fish distribution and fleet behavior. Effort-weighted glob al CPUE estimates indicate a 38% increase in halibut density in years following implementation of the quota program, while seasonally adjust ed area-weighted estimates show only a 16% increase. Two systematic sc ientific surveys conducted on a portion of this area in 1986 and 1993 showed a 132% increase in density, although high variation and bias in these estimates limited their significance. The composition of the fl eet remained relatively stable over this period making interactions in volving the factors of gear type and vessel size-class less significan t. Results of this analysis proved useful in planning survey and asses sment programs prior to implementing a similar quota program in Alaska .