The Fish Population Dynamics and Modeling Program conducts analyses in support of the Pacific Fishery Management Council's Fishery Management Plans for coastal pelagic species and highly migratory species. We also conduct analyses in support of U.S. participation in the International Scientific Committee for Tuna and Tuna-Like Species in the North Pacific Ocean, the Inter-American Tropical Tuna Commission, and the Western and Central Pacific Fisheries Commission. These analyses include stock assessments, sensitivity studies, development of population models, and management strategy evaluations.
Our primary goal is to analyze dynamics of targeted fish populations, determine stock status, and provide management advice regarding coastal pelagic species of the California Current Ecosystem and highly migratory species of the North Pacific Ocean. Our assessment scientists work toward reconstruction of abundance of targeted fish populations through time. Statistical models informed with biological, fishery removal, and relative abundance data are used to determine stock status relative to management objectives. The data includes growth, reproduction, natural mortality, catch and biological composition, fishery catch per unit of effort, and fishery-independent survey estimates.
Stock Assessment
We are responsible for assessing both highly migratory and coastal pelagic species that inhabit the northeast Pacific Ocean. Many of these stocks are trans-boundary, meaning they are also targeted by other Pacific nations, including Canada, Mexico, Japan, Korea, Chinese-Taipei, etc. These stocks require ongoing data exchange and collaborative assessment development. To accomplish this, our assessment scientists work within the structures of various domestic and international Regional Fishery Management Organizations and Regional Fishery Science Organizations.
For example, our assessment results and management advice on coastal pelagic species are provided to the Pacific Fishery Management Council, 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 to conduct collaborative assessments on tuna and shark stocks spanning the North Pacific.
Our scientists also perform advisory and reviewer roles to the stock assessments of international Regional Fishery Management Organizations like the Inter-American Tropical Tuna Commission. Stocks are assessed at different intervals, depending on need. Pacific sardine stocks are assessed annually while North Pacific albacore tuna is assessed tri-annually. Species with limited landings, such as Pacific mackerel, are assessed less regularly. 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 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 is a newly established collaborative effort between the Southwest Fisheries Science Center, Inter-American Tropical Tuna Commission, and Scripps Institution of Oceanography, U.C. San Diego.
The Center for the Advancement of Population Assessment Methodology was created in order to:
- Improve 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.
- Afford the educational and training opportunities necessary to produce competent researchers and the next generation of stock assessment scientists.
Since 2013, the Center for the Advancement of Population Assessment Methodology has hosted six international stock assessment workshops, papers from which have been published in six scientific journal special issues. Staff have taught 11 stock assessment courses in six different countries. Staff have been recognized for their efforts with national awards from the American Fishery Society and the American Institute of Fishery Research Biologists.
Climate Effects
NOAA Fisheries and the Environment program 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, and for developing an environmental time series to indicate the availability of the stock to fisheries in that region. A database containing daily, location-specific, catch and effort data from both albacore vessels has been assembled and converted into weekly fields of relative albacore catch per unit effort in the open and coastal ocean. Statistical models subsequently relate the relative catch per unit effort in these areas to the environment conditions.
Management Strategy Evaluation
Management strategy evaluation involves assessing the trade-offs of fishery management strategies and evaluating their consequences across a range of management objectives. The management strategy evaluation research ranges from application of simple models to developing biological reference points, such as maximum sustainable yield and depletion, to more complicated simulation models that evaluate performance measures, given a wide range of population dynamics and management approaches (harvest control rules). We have led a multi-year management strategy evaluation of North Pacific Albacore Tuna in coordination with stakeholders and fishery managers.
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 management team. We also participate in the different working groups for the International Scientific Committee, and on the Scientific Advisory Committee which provides review and advice to the Inter-American Tropical Tuna Commission.
