An independent science panel in a new 364-page report recommends that an effort be launched through the Columbia River Basin Fish and Wildlife Program to better understand an ever-changing and complicated food web that must sustain salmon and other species.
The report, “Columbia River Basin Food Webs: Developing a Broader Scientific Foundation for Fish and Wildlife Restoration,” is the culmination of a two-year undertaking aimed at providing a fundamental understanding of aquatic food webs in the basin and their effects on native fish restoration efforts. The report’s scope includes the tributaries, impoundments and mainstem Columbia and Snake rivers, as well as the estuary.
“Incorporating a food web perspective into management efforts helps sustain the ecological system and provide for more productive and resilient fisheries,” the Independent Scientific Advisory Board report says. Robert Naiman, lead reviewer, led an unveiling of the report to the Northwest Power and Conservation Council Tuesday with the help of co-authors Bruce Rieman, Richard Alldredge and Pete Bisson, all ISAB members. All 11 members of the panel took part in the review.
“… a focus on food webs provides a strong complement to the ongoing emphases on hydrosystem, habitat, hatcheries and harvest (the four H’s),” the report says.
The ISAB provides advice and recommendations on scientific and technical issues related to the Council's fish and wildlife program, tribal fish and wildlife programs, and the NOAA Fisheries recovery program for Columbia River basin salmonids. Much of the ISAB’s work is funded through the Council’s program, which itself is funded by the Bonneville Power Administration with ratepayer revenues. BPA markets power generated in the federal Columbia-Snake river hydro system.
The food web report and related interactive links can be found at:
To complete the report the ISAB compiled and reviewed the diverse literature to produce a coherent summary; identified future food web-related research directions for improving restoration of fish and wildlife in the basin; and presented current scientific understanding in a form that can be used by policy makers.
“The food web-related issues addressed in the report are numerous and complex, more so than initially imagined. Therefore, the ISAB felt that suggesting a time-prioritized action plan would be important,” according to the report’s introduction.
“The ISAB suggests that the Council consider a systematic action plan addressing the concerns outlined above. We envision a concerted 12-year plan with an estimated total cost of at least $20-25 M.
“The estimate is given only to provide an initial sense of the scope and scale of food web issues. Specific activities could be nested within the existing Fish and Wildlife Program, representing ~1 percent of annual budget. Some suggested projects fall naturally under Monitoring, as they involve determination of the state of the system, both in advance of intervention and for progressive monitoring as the effort unfolds. Some fall under Habitat, as they involve efforts at habitat manipulation and/or restoration/reclamation. Some fall under Production, as they involve adjustments to rearing and releasing fish, in what numbers, and where. The rest of the suggested activities fall under Research, particularly those aimed at filling information gaps,” the introduction says.
“Consideration of food web processes in fish and wildlife planning will help frame recovery actions that have a higher probability of achieving stated objectives over the coming decades. The identification of the types, location, and intensity of potential food web impacts on fish and wildlife should help ensure the long-term success of projects supported by the Fish and Wildlife Program.
“Food webs describe pathways by which energy, nutrients and other materials make their way to species of ecological, social, cultural and economic interest,” according to the report. “Food webs are often thought of as reflections of habitat, yet many other factors shape internal organization, linkages, productivity and resilience. Species diversity, the mix of native and non-native species, chemical contaminants, habitat carrying capacity, nutrient delivery and cycling, competition, predation, disease and associated system-scale processes are all deeply involved in shaping food webs.
“Food webs, although highly complex, have been successfully manipulated at large scales to improve water quality as well as recreational fisheries (e.g., Carpenter et al. 1985, 1995),” the report says. “Ill-advised manipulations of food webs have resulted in serious environmental issues – the introduction of Mysis, a freshwater shrimp, in the basin being one example (Spencer et al. 1991, Nesler and Bergersen 1991).”
The ISAB report also recommends the development of a comprehensive food web model to link fish growth to food web conditions in freshwater, estuarine, and marine habitats.
“Throughout this report, the need for better quantitative food web and related bioenergetic models has arisen repeatedly. The need for a major modeling effort to build a ‘total system model’ of the basin is abundantly clear,” the report says. “The effort would be large and would need to be sustained, but necessary for understanding the basin as an integrated system.
“The goal of the model would be to:
“-- Synthesize what we know about the biotic and abiotic factors, as well as processes governing food web structure and function – the foundation of the food web modeling platform.
“-- Challenge the structure and resilience / sensitivity of the resulting food webs, in the face of changing inputs. We envisage an effort on the pattern and scale of the COMPASS effort.
“-- Ground-truth (benchmark) model predictions against empiric reality for both the example cases used to construct the model and for others that it would mimic.”
To guide the review, the ISAB considered a number of fundamental questions concerning aquatic food webs that, if adequately addressed, could inform ongoing and future restoration efforts:
-- What are the quantifiable, system-scale impacts of sea lions and birds?
- What are the ecological consequences of changing the river from a primarily benthic-based production system to one that is now predominantly pelagic-based?
-- How do intensive and selective fisheries (e.g., Northern pikeminnow) reverberate through food webs?
-- What are the ecological consequences of the large numbers and consistent annual levels of salmonid hatchery releases?
-- Are the preferred foods of migrating juvenile salmon available in sufficient quantities, and at the right times?
-- How vulnerable are existing salmonid food webs to near term climate-induced changes?
-- Do marine-derived nutrients released from the bodies of spawning salmon contribute to the survivorship and productivity of the subsequent generation as well as enhance the productivity of the entire biotic community?
-- How might projected changes in agricultural land use and water withdrawals impact food web structure?
-- Can a general model be developed to predict the food web consequences of proliferating non-native species (e.g., shad, bivalves) on the foods of native species?