Collaborative management of a unique fishery on the Great Salt Lake

Phil BrownJohn LuftJohn NeillKyle Stone

Jim Vanleeuwen

Utah Division of Wildlife ResourcesGreat Salt Lake Ecosystem Program

Brine shrimp (Artemia franciscana)

• Zooplankton• 5-10mm length• Effective filter feeders• 3-4 generations per

year• Winter die-off• Produce diapausing

eggs (cysts)

Doyle Stephens, USGS

Small organisms, large role

At peak 2008 densities:• 5.8 shrimp/liter• 94,000 tons in lake• 13,400 bull African

elephants• 1.3 million people

• The only energy pathway for some important avian species

• Nutrient cycling• Phytoplankton control

NH4+

PO43-

Brine Shrimp Harvest• Adults harvested in small numbers—1950s• Expanded global aquaculture (shrimp, finfish) in

1980s led to harvest of cysts• Only cysts are targeted now, collection of adults only

allowed as bycatch

Brine Shrimp HarvestBrine Shrimp Harvest

• Rapid expansion in harvest—1990sRapid expansion in harvest—1990s• Number of harvest companies rose from 4 to 32 Number of harvest companies rose from 4 to 32

by 1996by 1996• No state/fed wildlife agency oversightNo state/fed wildlife agency oversight• Overharvest of resource was a concern for the Overharvest of resource was a concern for the

conservationists and shrimp companiesconservationists and shrimp companies• Recognized need for DWR regulationRecognized need for DWR regulation

• Cooperate with companies to establish harvest limit• Allow for a commercial harvest only after ecosystem

needs are met

• First program of its kind—no one else had studied a natural brine shrimp population

Great Salt Lake Ecosystem Great Salt Lake Ecosystem Program: 1996 to presentProgram: 1996 to present

Great Salt Lake Ecosystem Great Salt Lake Ecosystem ProgramProgram

• Determine harvestable surplus• Understand GSL from an ecosystem perspective• Required expertise outside DWR:

• Wayne Wurtsbaugh, Utah State University• Doyle Stephens, USGS• Gary Belovsky, Utah State University & Notre Dame

Adaptive management• Began with back-of-the-envelope

calculation with a 50% fudge factor….that turned out to be fairly accurate

• Massive data collection efforts• Predictive model developed by

Gary Belovsky predicts maximum cyst production

• Harvest allowed until cyst densities reach the cutoff

• 15 years of harvest without population crash

• Data collection and intensive monitoring continues to this day

Figure courtesy of Dr. Gary Belovsky

Research partnerships

• Notre Dame—Community ecology

• USGS—Limnological modeling

• USU—Avian ecology and contaminants

• Westminster College—brine shrimp genetics

• Utah DWQ—Contaminant studies

Phytoplankton60+ species3 guilds: Green algae, cyanobacteria, diatoms

Bioherms/stromatolites(Cyanobacteria)

Brine Shrimp Brine Flies

Eared Grebes

Phalaropes Gulls Common Goldeneye

PAR (sunlight)

Existing nutrient

poolSalinity

Inflowing nutrient supply

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GSL foodweb gaining complexity

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Still not as complex as freshwater systems

• Primary producers (many species)

• Primary consumers (12+ species)

• Secondary consumers (8 species)

• Tertiary consumers (5 species)

• Primary producers (60+ species)

• Primary consumers (2-3 species)

• Secondary consumers (1 part-time aquatic species, birds)

• Tertiary consumers (none)

Lake Michigan Great Salt Lake

NOAA Great Lakes Environmental Research Laboratory Great Lakes Fishery Commission

Issues of concern—Water quantity

• Proposed Bear River diversions– 250,000 acre-ft per year

• Proposed mineral evaporation pond expansions– 350,000 acre-ft per year

• Nearly 20% of current river inflow• Lake is already ~8 feet lower than natural state

Issues of concern—Water quality

• GSL is downstream of everything• Terminal lake—substances accumulate• Nutrient loading• Mercury• Selenium• Urban runoff• Pharmaceuticals

Watershed wide issuesWatershed wide issues

• Stakeholders now include major municipalities Stakeholders now include major municipalities and entire urban areasand entire urban areas

– Loss of reciprocity: their cooperation is Loss of reciprocity: their cooperation is critical to maintaining health of lake, but they critical to maintaining health of lake, but they may see little to gain by it. may see little to gain by it.

• Public perception of GSL is a problemPublic perception of GSL is a problem

• Few numeric water quality standardsFew numeric water quality standards

Questions are welcome

For additional information, two manuscripts are in preparation by Dr. Gary E. Belovsky and coauthors for the following topics:

• Great Salt Lake aquatic foodweb and brine shrimp population dynamics:

Belovsky, G.E. et al. The Great Salt Lake ecosystem (Utah, USA): long term data and a structural equation approach. Ecosphere. April 2011.

• Brine shrimp predictive model used for management of harvest

(in draft form)