The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners.
As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.
i
The utility of spatial model-based estimators of unobserved bycatch
-
2018
-
-
Source: ICES Journal of Marine Science, 76(1), 255-267
[PDF-2.87 MB]
Details:
-
Journal Title:ICES Journal of Marine Science
-
Personal Author:
-
NOAA Program & Office:
-
Description:Quantifying effects of fishing on non-targeted (bycatch) species is an important management and conservation issue. Bycatch estimates are typically calculated using data collected by on-board observers, but observer programmes are costly and therefore often only cover a small percentage of the fishery. The challenge is then to estimate bycatch for the unobserved fishing activity. The status quo for most fisheries is to assume the ratio of bycatch to effort is constant and multiply this ratio by the effort in the unobserved activity (ratio estimator). We used a dataset with 100% observer coverage, 35 440 hauls from the US west coast groundfish trawl fishery, to evaluate the ratio estimator against methods that utilize fine-scale spatial information: generalized additive models (GAMs) and random forests. Applied to 15 species representing a range of bycatch rates, including spatial locations improved model predictive ability, whereas including effort-associated covariates generally did not. Random forests performed best for all species (lower root mean square error), but were slightly biased (overpredicting total bycatch). Thus, the choice of bycatch estimation method involves a tradeoff between bias and precision, and which method is optimal may depend on the species bycatch rate and how the estimates are to be used.
-
Keywords:
-
Source:ICES Journal of Marine Science, 76(1), 255-267
-
DOI:
-
ISSN:1054-3139;1095-9289;
-
Publisher:
-
Document Type:
-
Rights Information:Other
-
Compliance:Library
-
Main Document Checksum:
-
Download URL:
-
File Type:
