Species associations of fifteen major commercial groundfish species in the
northeastern Pacific ocean and their spatial and temporal characteristics were studied
using Oregon bottom trawl logbook data, 1987 to 1993. Screening procedures were used
to remove questionable data from the original logbook files, which resulted in the
exclusion of information from 46% of the total available tows. Two multivariate methods,
detrended correspondence analysis (DCA) and Ward's method of hierarchical cluster
analysis were used to derive the association patterns of species and species groups. A
general linear model that was developed for the primary DCA axis suggested that the
species associations are strongly correlated with depth, but minimally correlated with the
other environmental variables that were examined (latitude, season, and year). The weak
correlations between DCA axis 1 and the temporal variables indicate that species
associations in the study region are fairly persistent over time. The same multivariate
techniques were used to examine possible sampling effects due to changes in the
participating trawl vessels that contributed logbook information. Depth and latitudinal
distributions of species occurrence in the logbook were similar to distributions derived
from National Marine Fishery Service triennial bottom trawl survey. However, the analysis
also showed that the depth coverage by the survey is not broad enough to accurately
characterize associations among species that are currently subject to commercial fishing
activity. / Graduation date: 1998
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33901 |
| Date | 29 August 1997 |
| Creators | Lee, Yong Woo |
| Contributors | Sampson, David B. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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