Bottomfish Research and Stock Assessment
Purpose
One of the primary goals of the Fishery Biology and Stock Assessment Division (FBSAD) at the Pacific Islands Fisheries Science Center (PIFSC) is to conduct research on the life history, ecology, and stock status of bottomfish species (snappers, groupers, and jacks) that support important, small-scale U.S. handline fisheries in the Pacific Islands Region. Recently, most of the research has been focused on stock assessment of bottomfish in the Hawaiian Archipelago. Results of these studies are used by the Western Pacific Regional Fishery Management Council and the NMFS Pacific Islands Regional Office to monitor and manage the limited-entry bottomfish fishery in the Northwestern Hawaiian Islands (NWHI) and to provide advice on conservation of bottomfish in the main Hawaiian Islands in conjunction with the State of Hawaii. The purpose of these Web pages is to provide information on the Center's bottomfish research and ready access to relevant publications and reports by Center scientists. These reports describe the data, methods, and results of bottomfish biological studies and stock assessments.
Reports
Overfishing Definitions, Reference Points, and Control Rules
This 2005 document provides a technical summary of the analytical procedure used since June 2004 by Center scientists to determine key information inputs needed to apply the bottomfish control rules and to determine whether the multi-species bottomfish stock complex, assessed on an Archipelago-wide basis, is being harvested within the approved conservation guidelines.
Published by PIFSC in May 2000. This report explains the formal approach taken by the Council, and endorsed by NOAA, to manage bottomfish fisheries in the Region in compliance with the Magnuson-Stevens Fisheries Conservation and Management Act and Sustainable Fisheries Act (SFA). The control rules were approved by the Secretary of Commerce.
Stock Assessments
"Hawaiian Bottomfish Assessment Update for 2008" (PDF)
This report describes an updated stock assessment of Hawaiian bottomfish conducted in 2008 based on re-audited bottomfish catch and effort data from commercial logbook records collected during 1948-2007. A standardized bottomfish catch-per-unit effort (CPUE) data set for the main Hawaiian Islands was constructed using the re-audited catch and effort data and a multiplicative log-linear estimation model. Bottomfish biomass and harvest rate time series through 2007 were estimated using a Bayesian state-space formulation of the dynamic Schaefer production model. The production model was fit to catch and standardized CPUE data for each of the three Hawaiian fishing zones: the main Hawaiian Islands zone, the Mau zone, and the Hoomalu zone. The production model fitting incorporated uninformative priors for carrying capacity, process error, observation error, and catchability parameters and an informative prior for intrinsic growth rate. The model was also used to conduct short-term projections of future catches and associated risks of overfishing. These projections explicitly included uncertainty in the posterior distribution of estimated bottomfish biomass in 2007 and population dynamics parameters.
"An Investigation of Alternative Production Models to Assess the Hawaiian Bottomfish Complex" (PDF)
In 2007, a Bayesian statistical framework was used to investigate alternative production models for assessing the Hawaiian bottomfish complex. As described in this report, the study greatly improved earlier results by providing direct estimates of uncertainty in the production model parameters.
"Status of the Hawaiian Bottomfish Stocks, 2004" (PDF)
This 2006 report provides details of an archipelago-wide stock assessment of Hawaiian bottomfish using a dynamic production model and catch data collected by NMFS and the State of Hawaii through 2004.
Additional research reports and stock assessments will be posted here as they become available. Please feel free to contact the Center for further information about our bottomfish research.
