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- Title
Is catch proportional to nominal effort? Conceptual, fleet dynamic, and statistical considerations in catch standardization.
- Authors
Aljafary, M.; Gillis, D.M.; Comeau, P.
- Abstract
Often, catch-per-unit-effort (CPUE) standardizations are used to reflect fish abundance. This implies that catch is directly proportional to effort. We examine this using 78 reported catch and effort series in a meta-analysis, correcting for errors-in-variables in the relationship. Though proportionality in the apparent relationship is the average, there is significant variation among fisheries. We then examine the Scotian Shelf haddock (Melanogrammus aeglefinus) fishery in detail. We used a generalized linear mixed model (GLMM) predicting catch-per-set, accounting for annual and within-year variation in fish, fleet activity, aggregation, and vessel locations and differences. In individual trawls, the catch was less than expected from a proportional relationship with effort. The GLMM revealed both interference and facilitation among vessels as well as autocorrelation among sets. The greatest impact on coefficient estimates was seen by allowing the effort coefficient to vary. Temporal aggregation made the catch–effort relationship appear more proportional. We recommend that fisheries researchers standardize catch explicitly, rather than CPUE, and use disaggregated data to more closely match the underlying relationships in the fisheries being examined.
- Subjects
STANDARDIZATION; FISHERIES; FISHES; TRAWLING; META-analysis
- Publication
Canadian Journal of Fisheries & Aquatic Sciences, 2019, Vol 76, Issue 12, p2332
- ISSN
0706-652X
- Publication type
Article
- DOI
10.1139/cjfas-2018-0303