Graduate Project
 

Using an indicator model to rank relative stock status of minor West Coast rockfish species

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_projects/37720h90v

Descriptions

Attribute NameValues
Creator
Abstract
  • Quantitative assessments of many West coast rockfish stocks of both major and minor importance to commercial fisheries have shown varying declines in abundances. The population sizes of less-abundant, co-occurring unassessed species may also be declining. However, determining stock status of the many non-targeted, minor species with high levels of certainty and quantifiable predictability may be prohibitively expensive and/or impractical because of the dearth of available data. Using a system of qualitative indicators may provide a cost-effective method to create preliminary assessments of the relative status of minor rockfish stocks and subsequently prioritize future studies. This project was undertaken to test a system of indicators to characterize the status of West Coast rockfish species including Sebastes aurora, S. babcocki, S. aleutianus, S. zacentrus, S. borealis, S. diploproa, and S. reedi. An array of indicators including catch per unit effort, the proportion of positive hauls, and length composition data were used to detect possible changes in the density, distribution, and size composition of the population. Data were taken from three West Coast bottom trawl surveys conducted by the National Marine Fisheries Service. The percentage of trends indicating linear decline were summarized and stocks were subsequently ranked in order of greatest concern over declining populations. S. babcocki was ranked as the stock of greatest concern with 52% of the indices showing negative trends while negative trends for S. diploproa, S. zacentrus, and S. borealis were found in 26%, 23%, and 20% of the indices, respectively. Less than 15% of determined trends were negative for S. aleutianus, S. aurora, and S. reedi. Our interpretation of the health of the population projected by the indicators was compared to the population status based upon formal stock assessments for four species, S. alutus, S. crameri, S. melanostomus, and S. rufus. Indicator-based assessments show potential to preliminarly assess numerous species simultaneously and identify species of greatest concern over declining populations.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Committee Member
Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
File Format
File Extent
  • 4445651 bytes
Digitization Specifications
  • Master files scanned at 600 ppi (24-bit Color) using Capture Perfect 3.0 on a Canon DR-9080C in TIF format. PDF derivative scanned at 300 ppi (24-bit Color) using Capture Perfect 3.0 and OmniPage Professional 15.0 for textual OCR on a Canon DR-9080C.
Replaces

Relationships

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details Miller_ocr.pdf 2017-10-23 Public Download