PFRP
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Integrative Modeling in Support of the Pelagic Fisheries Research Program: Spatially Disaggregated Population Dynamics Model for Pelagic FisheriesProgress Reports (PDF): FY 2012, FY 2011, FY 2010, FY 2009, FY 2008, FY 2007, SOEST-JIMAR report, FY 2006, FY 2005, FY 2004, FY 2003, FY 2002, FY 2001, FY 2000, FY 1999, FY 1998, FY 1997, FY 1996Project Overview Spatially disaggregated models of pelagic fisheries will be developed which attempt to integrate fish movement, behavior, economics and oceanographic information. Initially, an existing model of large scale skipjack movement will be extended to yellowfin tuna and to larger geographic areas in the Pacific. As PFRP results begin to accumulate, more flexible model parameterizations for relating movement parameters to geographic and oceanographic variables will be developed. In addition, economic predictors of fishing effort will be used to characterize fishing in such a way as to predict fish catches under different scenarios of fisheries development, fish population changes and oceanographic variability.
Project findings published as part of the SOEST-JIMAR
publication series:
See also Design
of tag-recapture experiments for estimating yellowfin tuna stock dynamics,
mortality and fishery interactions project
page.
See
SOEST-JIMAR Publications page
for other PFRP reports
Principal
Investigator:
Project Description Text of the 1998 project update is provided at the end of this section.Funding for this project was received in April 1994. The general objective of the proposed research is to integrate the results of different PFRP components into spatially disaggregated models of pelagic fisheries which integrate knowledge of fish movement, the fishing process, economics and oceanography. The character of this project was changed greatly by amalgamation with another PFRP project, "Design of tag-recapture experiments for estimating yellowfin tuna stock dynamics, movements, and fishery interactions". The status of the tag-design project is reported separately. The existing model western Pacific skipjack movement was modified to include both seasonal and spatial variability in diffusion. In addition, fishing effort observations, stratified by month and 1 degree geographic square, were included. This model was applied to skipjack tagging data from two South Pacific Commission tagging experiments and the results were used to analyze potential fishery interactions between purse seine and pole and line fisheries for skipjack. The results emphasized the importance of both directed and random components of movement in determining the large scale distribution of skipjack. Natural mortality emerged as an important determinant of the potential for fisheries interaction. The potential decline of pole and line catches of skipjack due to catches by the purse seine fleet ranged from 5% to 30% depending on distance between fisheries and natural mortality. This work was reported at the FAO expert consultation on interactions of Pacific Tuna Fisheries, Shimizu, Japan, January, 1995. The model software, originally written for personal computers, was modified to run on a Sun SPARCStation 20. A set of graphics routines was written that allow the same basic software to run on either a PC or an Xwindows terminal without modification to the source code. A preliminary model was developed which can, in principle, estimate movement and population dynamics parameters from the spatial distribution of catch and effort. Considerable work is required to get this model into working condition. The model was extended spatially in two different modes. The boundaries of the western Pacific skipjack model were extended to the Asian continent, 170\170W, 40\170S and 40\170N. This large model area will be used to analyze both yellowfin and skipjack tagging results. Scientists from the Tohoku Regional Fisheries Laboratory in Japan will be collaborating in the skipjack analysis. The model was also adapted to a different ocean basin including the entire North Atlantic Ocean, Caribbean and Mediterranean Seas in order to assist in planning a study of Atlantic bluefin tuna migrations. This work was done in collaboration NMFS scientists in La Jolla and Miami. You can see a movie of the modeling of the movements of tagged skipjack tuna in the South-West Pacific, for the period 10/1977 to 08/1982. (MPEG file 1.6M.) You can also see a movie of the sea surface temperatures in the South-West Pacific, for an arbitrary year. (MPEG file 107K.)
Progress Report - June 1998
BackgroundThe general objective of this research is to integrate the results of different components of the Pelagic Fisheries Research Program into a consistent framework that integrates knowledge of fish movement and population dynamics, the fishing process, economics and oceanography. The primary focus of is the development of spatial models of pelagic fish population dynamics that explicitly include movement, mortality, and fisheries. General Project Status Lack of an associate researcher on this project and the preoccupation of the PI (Dr. Sibert) with PFRP program administration and related activities has slowed progress on project goals. Collaborative work was begin in support of the PFRP project "A tag and release program for the Hawaiian seamount yellowfin and bigeye tuna handline and troll fisheries". A preliminary of yellowfin and bigeye movements between offshore fishing grounds analysis was completed using tag recaptures through mid 1997. Progress on 1997-98 Goals: 1. Continue development of habitat-based movement models. If feasible, output from oceanographic models to simulate "real time" observations of temperature and oxygen fields. Explore possibilities of including stock structure. The existing tag movement and estimation software was completely revised to facilitate compatible development of habitat and regional based movement models. Availability of real time observations of habitat variables on a large scale depends on year and area In the absence of observations predicted distributions of temperature, salinity and oxygen from GCMs have been used by collaborators at the SPC to generate fields of habitat variables from 1980 through 1995. Subsets of these variables will be used in the revised habitat model. 2. Complete analysis of SPC tuna tagging data and apply results to the analysis population exchanges within the WPRFMC area. The analysis of the 1978-82 SSAP skipjack tagging data was finalized and a manuscript was submitted for publication. Data for the 1989-1992 RTTP skipjack and yellowfin tagging data have been updated through 1995 and is currently being analyzed. This analysis should be complete by the end of the calendar year. 3. Continue collaboration with TNFRI (Tohoku National Fisheries Research Institute, Japan) scientists on analysis of north Pacific skipjack migration. The fishing effort data required to analyze the tagging data were extended back through 1988. Although estimation of movement patterns from this data set requires a great deal of computer time, progress is being made. Planned computer upgrades should decrease the computational time by a factor of two. This work should be complete during the next year. 4. Continue to improve numerical approximations to the partial differential equations used to model fish movement. A one-step, fully implicit, numerical solution to the diffusion-advection-reaction equation was implemented using a conjugate gradient algorithm. Although this method is somewhat less accurate than the semi-implicit ADI method, it is more general and enables more complex finite difference approximations to the advective terms. Goals for 1998-99: The social science components of the PFRP have made progress in expressing fishing effort as functions of external variables (e.g. costs of fuel, prices of fish, distance to fishing grounds). A new goal for the next year will be to begin to use the results in a small scale model of pelagic the fishery around Hawaii. The two PFRP tagging projects have produced impressive results. A new goal for the next year is to collaborate with Dr. Holland in analysis of these data. Other project goals for the next year will be substantially unchanged from the previous year. A post-doctoral fellow will be recruited as a visting scientist. 1. Begin to incorporate models of effort distribution into models of the Hawaii pelagic fishery. 2. Continue development of habitat-based movement models. If feasible, output from oceanographic models to simulate "real time" observations of temperature and oxygen fields. 3. Complete analysis of SPC tuna tagging data and apply results to the analysis population exchanges within the WPRFMC area. 4. Conclude analysis of north Pacific skipjack migration in collaboration with scientists from TNFRI (Tohoku National Fisheries Research Institute, Japan) and NRIFSF (National Research Institute of Far Seas Fisheries, Shimizu, Japan). 5. Continue to improve numerical approximations to the partial differential equations used to model fish movement. 6. Complete collaboration on analysis of yellowfin and bigeye movements using data from the Cross Seamount tagging project. 7. Begin collaboration on the analysis of tag recaptures from Hawaii regional tuna tagging project using both bulk transfer and diffusion models.
This page updated January 31, 2013 |
