Bottomfish Research and Stock Assessment
One of the primary goals of the Fisheries Research and Monitoring Division 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. fisheries in the Pacific Islands Region.
In recent years, most of the research has been focused on stock assessment of bottomfish in the Hawaiian Archipelago. Results of these studies have been used by the Western Pacific Regional Fishery Management Council and the NMFS Pacific Islands Regional Office to manage commercial bottomfish fisheries in the Northwestern Hawaiian Islands (NWHI) and the main Hawaiian Islands (MHI). The NWHI fishery ended in January 2010, so management is now directed solely at bottomfish fishing in the MHI. Likewise, the focus of biological research and stock assessment has shifted to the MHI, but issues of bottomfish metapopulation dynamics and broader ecosystem considerations may still require studies of bottomfish in the NWHI.
The purpose of these Web pages is to provide information on the Center's bottomfish research and stock assessment activities 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.
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.
In 2010, scientists at PIFSC conducted a stock assessment of the Deep7 complex using data through fishing year 2010 (viz., July 1, 2009 through June 30, 2010), including projections to determine total allowable commercial catches (TACs) and their probabilities of overfishing. The assessment was based on catch and effort data from commercial catch reports for the years 1948–2010, re-audited to correct flaws in previous data compilations. A standardized bottomfish catch-per-unit effort (CPUE) data set was constructed for the main Hawaiian Islands using re-audited catch and effort data. Model selection techniques were applied to choose the structural form on which CPUE standardization was based.
The 2010 stock assessment took into account recommendations of experts who reviewed the Hawaii bottomfish conducted in 2008. Those recommendations were made by the Western Pacific Stock Assessment Review panel and an independent reviewer provided by the Center for Independent Experts (CIE) in June 2009.
In support of the 2010 stock assessment, several ancillary studies were conducted and documented as PIFSC Internal Reports. In addition, the stock assessment cited results of a PIFSC contract report prepared in 2006 and the proceedings of a CPUE workshop held in 2008. When the stock assessment was published as a NOAA Technical Memorandum (link above), all of these supporting documents were also released. Links to the supplementary documents are provided below:
- A Review of Unreported to Reported Catch Ratios for Bottomfish Resources in the Main Hawaiian Islands (0.3 MB PDF)
- Estimation of Main Hawaiian Islands Bottomfish CPUE using the Delta Method and HDAR Catch Data for 1948–2010 (0.4 MB PDF)
- Investigation of the Association between Hawaii Deep Slope Bottomfish CPUE and Environmental Variables (0.2 MB PDF)
- Status and Trends of the Hawaiian Bottomfish Stocks: 1948–2004 (0.5 MB PDF)
- Bottomfish CPUE Standardization Workshop Proceedings August 4–6, 2008 (8.0 MB PDF)
The 2010 stock assessment was reviewed in early 2011 by 3 independent experts provided by the CIE. The reviewers' comments are posted elsewhere on this website [click here to read reviewer comments].
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. A peer review of the report was solicited through the Center for Independent Experts in July 2009.
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.
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.