Bristol Bay fisheries and water quality: what are the risks of - - PowerPoint PPT Presentation

Bristol Bay fisheries and water quality: what are the risks of mining development?

Daniel Schindler, PhD School of Aquatic and Fishery Sciences University of Washington

deschind@uw.edu

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http://www.absc.usgs.gov/research/Fisheries/Lake_Clark/subsistence.htm

Data from ADFG

Alaska fisheries are the envy of the world!

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North Pacific Ocean Bristol Bay

L.A. Rogers

each with many populations 9 major rivers

Salmon habitat in Bristol Bay

UW Fisheries Research Institute has monitored salmon and habitat in western Alaska continuously since 1946

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Bristol Bay watersheds are very wet and covered in porous gravels

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Chinook salmon – habitat use within watersheds (how consistent is production within individual tributaries?)

Nushagak River Chinook salmon

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Nushagak R. 2011 (n=255) 2011

Chinook salmon production in the Nushagak River

Brennan and Schindler (2016)

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Nushagak R. 2014 (n=279) 2014

Chinook salmon production in the Nushagak River

Brennan and Schindler (2016)

Bristol Bay salmon habitat operates like an investment portfolio – the aggregate is more stable and productive than the components

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Fine scale thermal heterogeneity

Bear Creek, 3km long

Habitat variation is also important within individual streams

7 ̊ C 12 ̊ C

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Jonny Armstrong

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• 2. 850-1300m: cold w/o sockeye
• 1. 0-850m: cold w/ sockeye
• 3. 1300m and up: warm w/o socke

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Juvenile coho salmon move between warm and cold sections of stream (habitat variation and connectivity is critical for juvenile salmon)

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Habitat variation within watersheds is what ultimately produces productive and reliable salmon returns

Subtle, chronic effects of infrastructure development simplifies salmon habitat and erodes its ability to produce stable salmon populations

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Cumulative risks to fish

• Acid mine drainage will occur (sulfuric acid)
• Copper has known direct and indirect toxic effects on

salmon (interferes with salmon’s ability to smell)

• Dust, groundwater, erosion make containment

challenging

• De-watering streams and wetlands (simplifying habitat)
• Loss of erosional processes that generate new habitat
• Roads, culverts, etc simplify habitat
• Some of these impacts are permanent (e.g. perpetual

storage and maintenance of tailings)

• Many of these risks take decades to express themselves
• Restoration is extremely expensive and often impossible

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It is easy to focus only on the risks of big catastrophes.

Samarco tailings dam Brazil 2015

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It is easy to focus only on the risks of big catastrophes… Need to be wary of death by a thousand cuts…

Mount Polley, British Columbia 2014

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Courtesy of Chris Stark, UAF

Chena River, Alaska

Road cutting off main river channel from ‘off-channel’ wetlands that are critical fish habitat Eliminates possibility for rejuvenation of habitat because river can’t migrate across floodplain

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