Are commercial logbook and scientific CPUE data useful for characterizing the spatial and seasonal distribution of exploited populations? The case of the Celtic Sea whiting

A statistical approach is proposed to utilize the information contained both in scientific surveys and commercial fishing logbooks, in order to determine spatial and temporal distributions of recruiting and spawning fish of exploited populations. The approach is based on multivariate descriptive methods including ordination methods and classification techniques. A typology involving a principal component analysis (PCA), followed by a hierarchical ascending classification (HAC), is applied to both scientific and commercial data. PCA that accounts for spatial and temporal contiguities were performed. These analyses allow to compare structures observed at global and local scales, with those observed without focusing on a particular scale. The method is applied to the whiting population in the Celtic Sea. The analyses performed on both scientific and commercial CPUE show that most age groups are found north of 50°N. The analysis of commercial CPUE indicates four periods in the year associated with particular areas. High abundances of adults (age >2 years) are observed during spawning season (January–April) in inshore areas (south of Ireland and off Cornwall). Intermediate abundances of adults are observed in the same area in May and June. Between July and September, all age groups are observed in the Smalls area, where particularly high abundance of recruiting group 1 are found. During the last quarter, the distribution of adults is more widespread, mainly ranging between 51°N and 52°N.