The Quantitative Modeling Group develops mathematical models to help fisheries biologists and resource managers adapt in the face of the extreme uncertainty that characterizes many marine ecosystems.
Members
Faculty
Villy Christensen
Villy Christensen works with ecosystem modeling and has a background in fisheries research. His research has, since 1990, been centered on understanding how human exploitation impacts marine ecosystems, and utilizes ecosystem modeling as the main tool. As part of this, he has been central to the development and dissemination of the Ecopath approach and software, and has, through cooperation with scientists worldwide, focused on trophic dynamics of aquatic resources. Ecopath modeling is the de-facto standard for ecosystem approaches to fisheries management, and is being applied throughout the world.
Murdoch McAllister
Murdoch McAllister’s research mainly involves developing and applying Bayesian statistical methods for fisheries risk assessment, estimation, decision analysis and management strategy evaluation. Applying Bayesian methods to fisheries stock assessment and providing quantitative decision support to non-governmental organizations, corporate clients, intergovernmental organizations, and government agencies are central to his work and to that of the members of his lab.
Steve Martell
Research in Steve Martell's lab is in the area of quantitative fisheries stock assessment. He uses computer models for estimating direct impacts of fisheries on individual fish stocks and indirect impacts of fisheries on the surrounding ecosystem. Computer models are also used to examine spatial management options such as closed areas and the effects of space-time variation in primary productivity on the distribution and production of marine organisms.
Carl Walters
"I mainly work on fish population dynamics, fisheries assessment and sustainable management". Carl Walters' areas of research include the development of rapid techniques for teaching systems analysis and mathematical modeling to biologists and resource managers. He believes the heart of fisheries is how to manage harvest: "The main thrust of my research is to figure out how to design management systems that are robust in an area of really high uncertainty". Carl Walters is the recipient of numerous awards, including the Killam Teaching Prize for Graduate Instruction (2009), the Timothy R. Parsons Medal (2007), the American Fisheries Society Award of Excellence (2006) and the The Volvo Environment Prize (with Ray Hilborn and Daniel Pauly; 2006).
| Dr Tom Carruthers | Stock assessment of Atlantic tropical tunas |
| Dr Sylvie Guénette | Impact of fishing on ecosystems and the use of marine reserves for conservation |
| Dr Matias Braccini | Population dynamics of elephant fish |
| Dr Robyn Forrest | Management Strategy Evaluation in US Gulf of Mexico reef fisheries |
| Dr Hiroyuki Kurota | Bayesian stock assessment modelling of kokanee-rainbow trout systems in British Columbian lakes |
| Dr Nathan Taylor | Atlantic bluefin tuna stock assessment |
| Robert Ahrens (PhD, Walters/Christensen) | Global analysis of apparent trends in abundance and recruitment of tunas and billfish vulnerable to pelagic longline gear |
| Meaghan Darcy (PhD, Martell) | Deriving species specific abundance information from aggregate commercial catch statistics |
| Mike Hawkshaw (PhD, Walters) | Dynamics of juvenile northern pikeminnow |
| Rachael Louton (PhD, McAllister) | Simulation evaluations of alternative management regimes for shrimp fisheries in the Gulf of Mexico |
| Michael Melnychuk (PhD, Walters) | Juvenile salmon during river and early ocean migrations: assessment of mortality with active and passive acoustic telemetry |
| Shannon Obradovich (PhD, McAllister) | Management Strategy Evaluation of inshore rockfish in British Columbia |
| Tom Porteus (PhD, McAllister) | Use of Bayesian methods to determine strategy for control of terrestrial vertebrate pest species |
| Erin Rechisky (PhD, Walters) | Early marine survival and migration of endangered Pacific salmon in the Columbia and Fraser rivers |
| Brett van Poorten (PhD, Walters) | Effects of interspecific competition on recruitment processes in rainbow trout and pygmy pikeminnow |
| Chad Wilkinson (MSc, Martell) | Bull trout and westslope cutthroat trout in the Elk River in southeast BC: using models for effective management |
Recent peer-reviewed publications
2009 and In press
Brown, C.J., Fulton, E.A., Hobday, A.J., Matear, R., Possingham, H., Bulman, C., Christensen, V., Forrest, R.E., Gehrke, P.C., Gribble, N.A., Griffiths S.P., Lozano-Montes, H., Martin, J.M., Metcalf, S., Okey, T.A., Watson, R., Richardson, A.J. In press. Effects of climate-driven primary production change on marine food webs: implications for fisheries and conservation. Global Change Biology.
Christensen, V., Walters, C.J., Ahrens, R., Alder, J., Buszowski, J., Christensen, L.B., Cheung, W.W.L., Dunne, J., Froese, R., Karpouzi, V., Kastner, K., Kearney, K., Lai, S., Lam, V., Palomares, M.L.D., Peters-Mason, A., Piroddi, C., Sarmiento, J.L., Steenbeek, J., Sumaila, R., Watson, R., Zeller, D. and Pauly, D. 2009. Database-driven models of the world’s large marine ecosystems. Ecological Modelling. 220:1984-1996.
Dulvy, N.K. and R.E. Forrest. In press. Life histories, population dynamics and extinction risks in chondrichthyans. Chapter 17 In The Biology of Sharks and their Relatives. Volume 2 – Physiological Adaptations, Behavior, Ecology, Conservation and Management of Sharks and Their Relatives. Edited by J. Carrier, J. Musick and M. Heithaus. CRC Press.
Forrest, R.E. and C.J. Walters. 2009. Estimating thresholds to optimal harvest rate for long-lived, low-fecundity sharks accounting for selectivity and density dependence in recruitment. Canadian Journal of Fisheries & Aquatic Sciences. 66: 2062-2080.
Greene, C.H., B.A. Block, D. Welch, G. Jackson, G.L. Lawson, E.L. Rechisky. 2009. Advances in conservation oceanography: New tagging and tracking technologies and their potential for transforming the science underlying fisheries management. Oceanography. Vol. 22, no. 1, pp 210-223.
Kurota, H., McAllister, M.K., Lawson, G.L., Nogueira, J.I., Teo, S.L.H. and Block, B.A. 2009. A sequential Bayesian methodology to estimate movement and exploitation rates using electronic and conventional tag data: application to Atlantic bluefin tuna (Thunnus thynnus). Canadian Journal of Fisheries and Aquatic Sciences 66: 321-342.
Ma, H., Townsend, H., Zhang, X., Sigrist, M., and Christensen, V. MS. In press. Using a fisheries ecosystem model with a water quality model to explore trophic and habitat impacts on fisheries stock: A case study of the blue crab population in Chesapeake Bay. Ecological Modelling.
Melnychuk, M.C. In press. Estimation of survival and detection probabilities for multiple tagged salmon stocks with nested migration routes, using a large-scale telemetry array. Marine & Freshwater Research.
Neira, S., C. Moloney, P. Cury, C. Mullon, and V. Christensen. In press. Mechanisms affecting recovery in an upwelling food web: the case of the southern Humboldt. Progress in Oceanography.
Rechisky, E.L., D.W. Welch, A.D. Porter, M.C. Jacobs, A. Ladouceur. 2009. Experimental measurement of hydrosystem-induced delayed mortality in juvenile Columbia River spring Chinook salmon using a large-scale acoustic array. Canadian Journal of Fisheries and Aquatic Sciences 66: 1019-1024.
Welch, D.W., M.C. Melnychuk, E.R. Rechisky, A.D. Porter, M.C. Jacobs, A. Ladouceur, R.S. McKinley, G.D. Jackson. 2009. Freshwater and marine migration pathways and survival of Cultus Lake sockeye salmon smolts determined using POST, a large-scale acoustic telemetry array. Canadian Journal of Fisheries and Aquatic Sciences. Vol. 66, pp 736-750.
Wilson, R.W., F.J. Millero, J.R. Taylor, P.J. Walsh, V. Christensen, S. Jennings, M. Grosell. 2009. Novel contribution of fish to the marine inorganic carbon cycle. Science 16 January 2009: 359-362. DOI: 10.1126/science.1157972.
2008
Allen, M. S., Walters, C.J., and Myers, R. 2008. Temporal trends in voluntary release of largemouth bass, with fishery implications. North Am. J. Fish. Mgmt. 28:418-427.
Forrest, R. E., S.J.D. Martell, M.C. Melynychuk, C. J. Walters 2008. An age-structured model with leading management parameters, incorporating age-specific selectivity and maturity. Can. J. Fish. Aquat. Sci. 65: 286-296.
Freire, K.M.F, Christensen, V., Pauly, D. 2008. Description of the East Brazil Large Marine Ecosystem using a trophic model. Scientia Marina 72(3):477-491.
Frisk, M.G., T.J. Miller, S.J.D. Martell, and K. Sosebee. 2008. New hypothesis helps explain elasmobranch outburst on Georges bank in the 1980s. Ecological Applications. 18: 234-245.
Gascuel, D., Morissette, L., Palomares, M.L.D. and Christensen, V. 2008. Trophic flow kinetics in marine ecosystems: Toward a theoretical approach to ecosystem functioning. Ecological Modelling, 217:33-47
Guénette, S, Christensen, V, Pauly, D. 2008. Trophic modeling of the Peruvian upwelling ecosystem: towards reconciliation of multiple datasets. Progress in Oceanography 792-4):326-335, doi:10.1016/j.pocean.2008.10.005.
Lindley, S. T., M. L.Moser, D. L.Erickson, M. Belchik, D. W.Welch, E. L. Rechisky, J. T. Kelly, J. Heublein, A. P. Klimley. 2008. Marine migration of North American green sturgeon. Transactions of the American Fisheries Society. Vol. 137, no. 1, pp. 182-194.
Martell, S. J. D., C. J. Walters, and R. Hilborn. 2008. Retrospective analysis of harvest management performance for Bristol Bay and Fraser River sockeye salmon (Oncorhynchus nerka. Can. J. Fish. Aquat. Sci. 65:409-424.
Martell, S.J., and Walters, C.J. 2008. Experimental policies for rebuilding depleted stocks. Can. Welch, D.W., Rechisky, E.L., Melnychuk, M.C., Porter, A.D., Walters, C.J., Clements, S, Clemens, B.J., McKinley, R.S., and Shreck, C. 2008. Survival of migrating salmon smolts in large rivers with and without dam. sPLoS Biol 6(10): e265. doi:10.1371/journal.pbio.0060265.
Martell, S.J., Walters, C.J., and Sumaila, U.R. 2008. Industry-funded fishing license reduction good for both profits and conservation. Fish and Fisheries 9:1-12.
Martell, S.J.D. and Walters, C.J. 2008. Experimental policies for rebuilding depleted stocks. Can. J. Fish. Aquat. Sci. 65: 1601-1609.
Martell, Steven JD, William E. Pine III., and Carl J. Walters 2008. Parameterizing age-structured models from a fisheries management perspective, Can. J. Fish. Aquat. Sci. 65: 1586-1600.
Michielsens, C. G.J. McAllister, M.K., Kuikka, S., Mäntyniemi, S., Romakkaniemi, Pakarinen, T., Karlsson, L., and Uusitalo, L. 2008. Combining multiple Bayesian data analyses in a sequential framework for quantitative fisheries stock assessment. Can. J. Fish Aquat. Sci. 65: 962-974.
Pine, W.E., Martell, S.J.D., Jensen, O.P., Walters, C., and Kitchell, J.F. 2008. Catch-and-release and size limit regulations for blue, white, and striped marlin: the role of postrelease survival in effective policy design. Can. J. Fish. Aquat. Sci. 65:975-988.
Walters, C. J., S.J.D. Martell, V. Christensen, B. Mahmoudi, 2008. An Ecosim model for exploring Gulf of Mexico ecosystem management options: implications of including multistanza life history models for policy predictions. Bull. Mar. Sci. 83 251-271.
Walters, C.J., Hilborn, R., and Christensen, V. 2008. Dynamics of surplus production in declining and increasing populations. Can. J. Fish. Aquat. Sci. 65:2536-2551.
Walters, C.J., R. Hilborn, V. Christensen. 2008. Surplus production dynamics in declining and recovering fish populations. Canadian Journal of Fisheries and Aquatic Research 65:2536-2551. (doi:10.1139/F08-170)
Welch, D.W., E.L. Rechisky, M.C. Melnychuk, A.D. Porter, C.J. Walters, S. Clements, B.J. Clemens, R.S. McKinley, C. Schreck. 2008. Survival of migrating salmon smolts in large rivers with and without dams. PLoS Biology Vol. 6, Issue 10, p e265, doi:10.1371/journal.pbio.0060265.
Wells, R.J.D., Cowan, J.H. Jr., Patterson, W.F. III, and Walters, C.J. 2008. Effect of trawling on juvenile red snapper habitat selection and life history parameters. Can J. Fish. Aquat. Sci. 65 (in press.
Zeller, D., Darcy, M., Booth, S., Lowe, M. K., and Martell, S. J. 2008. What about recreational catch? Potential impact on stock assessment for Hawaii’s bottomfish fisheries. Fisheries Research, doi:10.1016/j.fishres.2007.11.010
2007
Christensen, V., Aiken, K.A., Villanueva, M.C. 2007. Threats to the ocean: on the role of ecosystem approaches to fisheries. Social Science Information: 46(1): 67-86.
Coggins, L., Catalano, M.J., Allen, M.S., Pine, W.E., and Walters, C. 2007. Effects of cryptic fishing mortality on fishery sustainability and performance. Fish and Fisheries (In press.
Cunningham, C.L., Reid, D.G., McAllister, M.K., Kirkwood, G.P., C.D. Darby. 2007. A Bayesian State-Space Model for mixed-stock migrations, with application to Northeast Atlantic Mackerel Scomber scombrus. Afr. J. Marine Science. 29(3): 347-357.
Freire, K.M.F., Christensen, V., Pauly, D. 2007. Assessing fishing policies for northeastern Brazil. Pan-American Journal of Aquatic Sciences 22): 113-130.
Heymans, J.J., Guénette, S., and Christensen, V. 2007. Evaluating network analysis indicators of ecosystem status in the Gulf of Alaska. Ecosystems: 10(3):488-502
Martell, S.J., Walters, C., and Hilborn, R. 2007. Retrospective analysis of harvest management strategies for Fraser River and Bristol Bay sockeye salmon (Oncorhynchus nerka. Can. J. Fish. Aquat. Sci. 65:409-424.
Melnychuck, M., Welch, D., Walters, C., and Christensen, V. 2007. Riverine and early ocean migration and mortality patterns of juvenile steelhead trout ( Oncorhynchus mykiss ) from the Cheakamus River, British Columbia. Hydrobiologia 582:55-65.
Walters, C and V. Christensen. 2007. Adding realism to foraging arena predictions of trophic flow rates in Ecosim ecosystem models: shared foraging arenas and bout feeding. Ecological Modelling 209:342-350.
Walters, C. 2007. Is adaptive management helping to solve fisheries problems? Ambio 36:304-307.
Walters, C., Hilborn, R., and Parrish, R. 2007. An equilibrium model for predicting the efficacy of marine protected areas in coastal areas. Can. J. Fish. Aquat. Sci. 64:1009-1018.
Walters, C., Martell, S.J.D., and Christensen, V. 2007. An Ecosim model for exploring ecosystem management options for the Gulf of Mexico: implications of including multistanza life history models for policy predictions. Bull. Mar. Sci. (in press.
Walters, C., V. Christensen. 2007. Adding realism to foraging arena predictions of trophic flows in Ecosim ecosystem models: shared foraging arenas and bout feeding. Ecol. Modeling 209:342-350.
2006
Clarke, S., Jennifer E. Magnusson, Debra L. Abercrombie, Murdoch McAllister and Mahmood S. Shivji 2006. Identification of shark species composition and proportion in the Hong Kong shark fin market using molecular genetics and trade records. Conservation Biology. 20: 201-211.
Clarke, S.C., McAllister, M.K., Milner-Gulland, E.J., Kirkwood, G.P., Michielsens, C.G..J., Agnew, D..J., Pikitch, E. K., Nakano, H., Shivji, M. 2006. Global estimates of shark catches using trade records from commercial markets. Ecology Letters 9: 1-12.
Coggins, L. G. J., W. E. I. Pine, C. J. Walters, and S. J. D. Martell. 2006. Age-structured mark recapture analysis: A virtual-population-analysis-based model for analyzing age-structured capture-recapture data. North American Journal of Fisheries Management 26:201-205.
Coggins, L.G., Jr, W. E. Pine, III, C. J. Walters, D. R. Van Haverbeke, D. Ward, and H. C. Johnstone. 2006. Abundance Trends and Status of the Little Colorado River Population of Humpback Chub. North Am. J. Fish. Man. 26:76-88.
Guénette, S., Heymans, J. J., Christensen, V., and Trites, A. W. 2006. Ecosystem models show combined effects of fishing, predation, competition, and ocean productivity on Steller sea lions (Eumetopias jubatus) in Alaska. Can. J. Fish. Aquat. Sci., 63:2495-2517
Hrabik, T., Jensen, O., Martell, S., Walters, C., Kitchell, J. 2006. Diel vertical migration in the Lake Superior fish community I: variability in space and time. Can. J. Fish. Aquat. Sci. 63: 2286:2295.
Jensen, O. P., T. R. Hrabick, S. J. D. Martell, C. J. Walters, and J. F. Kitchell. 2006. Diel vertical migration in the Lake Superior pelagic community. II. modeling trade-offs at an intermediate trophic level. Can. J. Fish. Aquat. Sci. 63:2296-2307.
Kitchell, J. F., S. J. D. Martell, C. J. Walters, O. P. Jensen, I. Kaplan, J. Watters, T. E. Essington, and C. H. Boggs. 2006. Billfishes in an ecosystem context. Bull. Mar. Sci. 79:669-682.
Libralato, S., V. Christensen and D. Pauly. 2006. A method for identifying keystone species in food web models. Ecological Modelling, 195:153-171.
Melis, T. S., S. J. D. Martell, L. G. Coggins. Jr., I. W.E. Pine, and M. E. Andersen. 2006. Adaptive management of the Colorado River ecosystem below Glen Canyon Dam, Arizona: using science and modeling to resolve uncertainty in river management. In: Proceedings of the American Water Resources Association URL ttp://www.awra.org/proceedings/cd_proceedings.html.
Michielsens, C. G.J. McAllister, M.K., Kuikka, S., Pakarinen, T., Karlsson, L. Romakkaniemi, A., Perä, I., and Mäntyniemi, S. A. 2006. “Bayesian state-space mark-recapture model to estimate exploitation rates in mixed stock fisheries”. Can. J. Fish Aquat. Sci. 63:321-334.
Post, J.R., B.T. van Poorten, T. Rhodes, P. Askey, A. Paul. 2006. Fish entrainment into irrigation canals: an analytical approach and application to the Bow River, Alberta, Canada. North American Journal of Fisheries Management 26:875-887.
Walters, C. J., S. J. D. Martell, and J. Korman. 2006. A stochastic approach to stock reduction analysis. Can. J. Fish. Aquat. Sci. 63:212-223.
2005
Daan, N., V. Christensen and P. Cury (Eds.) 2005. Quantitative Ecosystem Indicators for Fisheries Management. ICES Journal of Marine Science 62(3):308-615. (Special issue)
Lessard, R. B., S. J. D. Martell, C. J. Walters, T. E. Essington and J. F. Kitchell 2005. Should Ecosystem Management Involve Active Control of Species Abundances?. Ecology and Society 10 2): 1. [online] URL: http://www.ecologyandsociety.org/vol10/iss2/art1/
Martell, S. J. D., T. E. Essington, B. Lessard, J. F. Kitchell, C. J. Walters, and C. H. Boggs. 2005. Interactions of productivity, predation risk, and fishing effort in the efficacy of marine protected areas for the central Pacific. Can. J. Fish. Aquat. Sci. 62:1320-1336.
Sherman, K., Sissenwine, M., Christensen, V., Duda, A., Hempel, G., Ibe, C., Levin, S., et al. 2005. A global movement toward an ecosystem approach to management of marine resources. Marine Ecology Progress Series 300, 275-279.
Taylor, N. G., C. J. Walters and S. J. D. Martell 2005. A new likelihood for simultaneously estimating von Bertalanffy growth parameters, gear selectivity, natural and fishing mortality. Can. J. Fish. Aquat. Sci. 62: 215-223.
van Poorten, B.T., J.R. Post. 2005. Seasonal fishery dynamics of a previously unexploited rainbow trout population with contrasts to established fisheries. North American Journal of Fisheries Management 25:329-345.
Walters, C. J., Christensen, V., Martell, S. J., and Kitchell, J. F. 2005. Possible ecosystem impacts of applying MSY policies from single-species assessment. ICES Journal of Marine Science, 62(3):558-568.
Walters, C., Hilborn, R. 2005. Exploratory analysis of recruitment trends using relative abundance and catch data. Can. J. Fish. Aquat. Sci. 62:1985-1990.
Walters, C., Korman, J., and McAdam, S. 2005. An assessment of white sturgeon status and trends in the lower Fraser River. Can. Science Advisory Secretariat (CSAS) Res. Doc. 2005/066, 60 p. [Online] URL: http://www.dfo-mpo.gc.ca/csas/Csas/Publications/ResDocs-DocRech/2005/2005_066_e.htm.
Watson, R., J. Alder, V. Christensen and D. Pauly. 2005. Mapping global fisheries patterns and their consequences. Part I,2 In: D.J. Wright and A. Scholz (eds. Place Matters – Geospatial Tools for Marine Science, Conservation and Management in the Pacific Northwest. Oregon State University Press, Corvallis. 272 pp.
2004
Christensen, V. and C. J. Walters. 2004. Ecopath with Ecosim: methods, capabilities and limitations. Ecol. Model. 172:109-139
Christensen, V. and C. J. Walters. 2004. Trade-offs in ecosystem-scale optimization of fisheries management policies. Bull. Mar. Sci., 74(3):549-562
Christensen, V., and J. Maclean, (Eds.) 2004. Placing fisheries in their ecosystem context. Ecological Modelling 1722-4):102-438, (Special issue)
Christensen, V., S. Guenette, J.J. Heymans, C.J. Walters, R. Watson, D. Zeller, and D. Pauly. 2004. Hundred year decline of North American predatory fishes. Fish and Fisheries. 4(1):1-24.
Kavanagh, P., N. Newlands, V. Christensen and D. Pauly. 2004. Automated parameter optimization for Ecopath ecosystem models. Ecol. Model. 172:141-149
Kitchell, J.F., I.C. Kaplan, S.P. Cox, S.J.D. Martell, T.E. Essington, C.H. Boggs, and C. Walters. 2004. Ecological and economic components of alternative fishing methods to reduce by-catch of marlin in a tropical pelagic ecosystem. Bull. Mar. Sci. 74: 607-619.
McAllister, M.K., Hill, S., Agnew, D., Kirkwood, G., and Beddington, J. 2004. “A Bayesian hierarchical formulation of the De Lury stock assessment model for abundance estimation of Falklands squid”. Can. J. Fish. Aquat. Sci. 61:1048-1059.
Martell, S.J.D., T. Essington, R. Lessard, J.F. Kitchell, C. Walters, and C.H. Boggs. 2004. Interactions of productivity, predation risk, and fishing effort in the efficacy of marine protected areas for the central Pacific. Can. J. Fish. Aquat. Sci. :1320-1336.
Michielsens, C. and McAllister, M.K. 2004. "A Bayesian hierarchical meta-analysis of stock-recruitment functions for Atlantic salmon: quantifying structural and parameter uncertainties”. Can. J. Fish. Aquat. Sci. 61:1032-1047.
Shannon, L. J., Christensen, V., and Walters, C. 2004. Modelling stock dynamics in the southern Benguela ecosystem over the last twenty five years. African Journal of Marine Science, 26: 179-196.
Walters, C.J. 2004. Simple representation of the dynamics of biomass error propagation for stock assessment models. Can. J. Fish. Aquat. Sci. 61: 1061-1065.
Walters, C.J. and S.J.D. Martell. 2004. Fisheries Ecology and Management. Princeton University Press, Princeton, New Jersey.