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 1
Alaska fisheries are the envy of the world! Data from ADFG 2 http:// www.absc.usgs.gov/research/Fisheries/Lake_Clark/subsistence.htm
Salmon habitat in Bristol Bay 9 major rivers North Pacific Ocean each with Bristol Bay many populations UW Fisheries Research Institute has monitored salmon and habitat in western Alaska continuously since 1946 3 L.A. Rogers
Bristol Bay watersheds are very wet and covered in porous gravels 4
Chinook salmon – habitat use within watersheds (how consistent is production within individual tributaries?) Nushagak River Chinook salmon 5
Chinook salmon production in the Nushagak River 2011 Nushagak R. 2011 (n=255) Brennan and Schindler (2016) 6
Chinook salmon production in the Nushagak River 2014 Nushagak R. 2014 (n=279) Brennan and Schindler (2016) Bristol Bay salmon habitat operates like an investment portfolio – the aggregate is more stable and productive than the components 7
Fine scale thermal heterogeneity Habitat variation is also important within individual streams 7 ̊ C 12 ̊ C Bear Creek, 3km long 8
9 Jonny Armstrong
1. 0-850m: cold w/ sockeye 3. 1300m and up: warm w/o socke 2. 850-1300m: cold w/o sockeye 10
Juvenile coho salmon move between warm and cold sections of stream (habitat variation and connectivity is critical for juvenile salmon) 11
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 12
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 13
It is easy to focus only on the risks of big catastrophes. Samarco tailings dam Brazil 2015 14
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 15
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 Courtesy of Chris Stark, UAF 16
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