Fish Population Dynamics and Modeling

The Population Dynamics and Modeling group conducts analyses in support of the Pacific Fishery Management Council's The previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer Fishery Management Plans for Coastal Pelagics Species and Highly Migratory Species.  The group also conducts analyses in support of U.S. participation in the International Scientific Committee for Tuna and Tuna-Like Species in the North Pacific Ocean (ISC), the Inter-American Tropical Tuna Commission (IATTC), and the Western and Central Pacific Fisheries Commission (WCPFC).  These analyses include stock assessments, sensitivity studies, and development of population models. 

Population Dynamics Program
The primary goal of the Population Dynamics program is to analyze dynamics of exploited fish populations, determine stock status, and provide management advice regarding coastal pelagic species (CPS) of the California Current Ecosystem and highly migratory species (HMS) of the North Pacific Ocean. Stock assessment is at the core of NOAA’s science-based management and is the primary function of the Population Dynamics program. Our assessment scientists work toward reconstruction of abundance of exploited fish populations through time. Statistical models informed with biological (e.g., growth, reproduction, natural mortality), fishery removal (e.g., catch and biological composition), and relative abundance (e.g., fishery catch-per unit of effort and/or fishery-independent survey estimates) data are used to determine stock status relative to management objectives. 

Population Dynamics and Modeling Staff

Assessment of the Pacific Sardine Resource in 2014 for U.S.A. Management in 2014-15

Primary Activities

Stock assessment
Stock assessment is at the core of NOAA’s science-based management and is the primary function of the Population Dynamics program. Our assessment scientists work toward reconstruction of abundance of exploited fish populations through time. Statistical models informed with biological (e.g., growth, reproduction, natural mortality), fishery removal (e.g., catch and biological composition), and relative abundance (e.g., fishery catch-per unit of effort and/or fishery-independent survey estimates) data are used to determine stock status relative to management objectives. 

The SWFSC is responsible for assessing both highly migratory and coastal pelagic species that inhabit the northeast Pacific Ocean. Many of these stocks are trans-boundary (i.e., also targeted by other Pacific nations, including Canada, Mexico, Japan, Chinese-Taipei, etc.), requiring ongoing data exchange and collaborative assessment development. Our assessment scientists work within the structures of various domestic and international Regional Fishery Management Organizations (RFMOs) and Regional Fishery Science Organizations (RFSOs). For example, our assessment results and management advice on CPS are provided to the Pacific Fishery Management Council (PFMC), while our scientists work with scientists from other nations within the International Scientific Committee on Tuna and Tuna-like Species in the North Pacific Ocean (ISC) to conduct collaborative assessments on tuna and shark stocks spanning the North Pacific.  In addition, our scientists also perform advisory and reviewer roles to the stock assessments of international RFMOs like the Inter-American Tropical Tuna Commission (IATTC). Stocks are assessed at different intervals, depending on need (e.g., annually for Pacific sardine, tri-annually for North Pacific albacore tuna, and less regularly for species with limited landings, such as Pacific mackerel). New assessments for other species are at various stages of development, including northern anchovy, jack mackerel, and shortfin mako sharks.

Modeling research and education
Our scientists are also researching approaches for improving stock assessment through advancements in modeling and data collection. Research has focused on the application of simulation methods to identify model misspecification of natural mortality, selectivity, spawner-recruit relationships, movement and spatial structure. The Center for the Advancement of Population Assessment Methodology (CAPAM) is a newly established collaborative effort between the Southwest Fisheries Science Center (SWFSC), Inter-American Tropical Tuna Commission (IATTC), and Scripps Institution of Oceanography (SIO, University of California, San Diego). CAPAM was created for the purposes of (1) improving quantitative methods generally used in stock assessment modeling efforts, whereby research is focused on parameterization and simulation involved in determining good practices for developing robust fishery models for management; and (2) affording the educational and training opportunities necessary to produce competent researchers and the next generation of stock assessment scientists. For example, in March 2013, the CAPAM hosted a 4-day workshop that focused on Selectivity: theory, estimation, and application in fishery stock assessment models and coordinated a special issue in a professional fishery journal that included manuscripts developed from research initially presented at the workshop.

Climate effects
Recent NOAA FATE project funding has been used to improve our understanding of how changes in environmental conditions influence the spatial distribution of north Pacific albacore tuna  in the northeast Pacific Ocean (NEPO), and for developing an environmental time series that indicates the availability of the stock to NEPO fisheries. A database containing daily, location-specific, catch and effort data from both albacore vessels in the NEPO, has been assembled and converted into weekly fields of relative albacore CPUE in the open and coastal ocean. Statistical models subsequently relate the relative CPUE in these areas to the environment conditions in these areas.

Management strategy evaluation
Management strategy evaluation (MSE) involves assessing the trade-offs of fishery management strategies and evaluating their consequences across a range of management objectives. The MSE research  ranges from application of simple models to developing biological reference points (e.g., FMSY, BMSY, depletion) to more complicated simulation models that evaluate performance measures, given a wide range of population dynamics and management approaches (harvest control rules). The Population Dynamics Group is not heavily involved in MSE research at present, however, there is a great need to develop MSEs for stocks under our purview. We are working to expand our workforce and address this gap.

Management advice
Population dynamics scientists actively participate on scientific committees and review panels for a number of regional fishery management organizations. We currently serve on formal management teams associated with the Pacific Fishery Management Council, including the coastal pelagic and highly migratory species management teams. We also participate in the different working groups for the International Scientific Committee (ISC). Finally, review and advice is provided to the Inter-American Tropical Tuna Commission (IATTC) through their Scientific Advisory Committee.

Significant Program Publications

Last modified: 2/27/2015