Status and Trends of the Lake Superior Fish Community,

Status and Trends of the Lake Superior Fish Community, 1978-2015 An Overview of the USGS Lake Superior Monitoring and Research Program Owen Gorman, Mark Vinson & Daniel Yule Lake Superior Biological Station Annual Meeting of the Wisconsin Land & Water Conservation Association Elkhart Lake, Wisconsin, Osthoff Resort March 2, 2016

Status and Trends of the Lake Superior Fish Community Lake Superior Biological Station Program R/V Kiyi R/V Siscowet

LSBS Program Early years (1958-1977) emphasized gillnet and bottom trawl surveys focused on lake trout restoration and defining prey base (single species management paradigm) Middle years (1978-1999) emphasized lake-wide bottom trawl monitoring to assess prey fish abundance for lake trout (fish community management paradigm) R/V Siscowet

LSBS Program Later years (2000-2004) expanded trawl surveys to deepwater habitat to better describe the deepwater fish community (whole lake assessment) More recently (2003-2015) application of hydroacoustics; provide more precise estimates of preyfish abundance useful for setting limits for harvest New studies in 2005-present integrated multiple sampling methodologies across habitats and trophic levels; increased knowledge of production and energy transfer via fish-mediated habitat coupling. Emphasis on ecosystem modeling and function (ecosystem restoration and management paradigm). R/V Kiyi

USGS Fisheries Science - Trawling

USGS Fisheries Science Hydroacoustics Zooplankton Neuston

Where to sample? What you catch depends on where you sample, and what you sample with. U.S. Geological Survey Lake Superior Biological Station 1957 to present Bottom trawls, 13,000 at 250 sites Gillnet sets, 2019 at 1,245 sites Mid-water trawls, 650 at 466 sites Hydroacoustic transects, >200

2001-2006 Offshore Sites 2001-2014 Sampling Locations Nearshore sites sampled, annually 51-86 Deepwater sites sampled 73 Offshore CSMI sites sampled 57

USGS Lake Superior Annual Fish Surveys ~120 sites per year, 84 nearshore, 36 offshore What s in the sample? How does it compare to previous years?, 75 days, 6,000 miles, 0.001% of the lake sampled Why is it different?

Lake Superior Depth Zones 0-15 m 15-80 m >80 m >250 feet > 80 m depth (77% of surface area) Lake Superior is a Siscowet Lake! 80 m depth (23% of surface area)

cisco bloater kiyi rainbow smelt Photo by Owen Gorman shortjaw cisco Lake Superior Fishes lake whitefish Photo by Owen Gorman Photo by Owen Gorman siscowet lake trout Photo by Owen Gorman lean lake trout burbot Photo by Owen Gorman Sulpins: slimy, spoonhead, deepwater

Societal dilemmas Native vs. exotic communities: Lake trout, Ciscoes, Sculpins vs. Pacific salmon, Alewife, Smelt, Goby How did we get here? Where do we go from here? See Dettmers et al. (2012, 2014) and Claramunt and Clapp (2014) for a recent debate. 32% of articles cited by these papers written by GLSC scientists

Bloater chub fishery collapse in Lake Michigan; August 13, 2011 Salmon collapse hits Lake Huron hard and fast; December 7, 2014

Commercial yield of lake herring, rainbow smelt, and lake trout from Lake Superior, 1879-2003 20000 Harvest, 1000s of pounds 18000 16000 14000 12000 10000 8000 6000 4000 2000 Lake herring Smelt Lake trout 25 20 15 10 5 LKT CPUE, No. fish / 1000 m / night 0 1879 1887 1895 1903 1911 1919 1927 1935 1943 1951 1959 1967 1975 1983 1991 1999 Year 0 Data from 1879-1977 are from Baldwin et al. (1979), data from 1978-2003 are from Mattes (2004), LKT data from 1929-1999 are from Wilberg et al. (2003)

Photo by Owen Gorman Photo by Owen Gorman Sea lamprey (introduced) Victim: hatchery lake trout

Lake Superior Success Story: Restoration of wild Lake Trout Shown are trends in mean relative density (fish/ha) of age-1 and older Lake Trout for all nearshore sampling stations in Lake Superior, 1978-2015. Relative Density (fish / ha) Relative Density (fish / ha) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Hatchery lake trout 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Year Wild (lean) lake trout 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Year <226 226-400 >400 <226 226-400 >400 Relative Density (fish / ha) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Siscowet lake trout 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Year <226 226-400 >400

Lake Superior Fish Community: Trends in Relative Biomass, 1978-2015 Relative Biomass (kg/ha) 25 20 15 10 Other L. Whitefish Bloater Cisco R. Smelt All Lake Trout 5 0 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2009: 1.12 kg/ha - lowest biomass on record: 2012: 1.20 kg/ha Year 1983: 2.15 kg/ha

Relative Biomass (Kg/Ha) 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 Trends in Lake Superior Nearshore Prey Fishes, Other 1991-2015 L. Whitefish Bloater Cisco 52% 38% 21% 21% 16% 2.0 Smelt 0.0 1991-1995 1996-2000 2001-2005 2006-2011 2006-2010 2011-2015 Interval Other R. Smelt Other Cisco Other Cisco L. Whitefish Cisco Bloater R. Smelt L. Whitefish Bloater R. Smelt L. Whitefish Bloater SJ Cisco SJ Cisco

Change in the Lake Superior Nearshore Fish Community Structure 1978-2015 III. 1986 + cisco + bloater + wild lake trout 1990 1992 I. 1979 1995 1985 1993 1989 1991 1994 Factor 1 1978 1987 1984 1996 1998 1988 1999 2001 + smelt + hatchery lake trout + demersal spp. - lake whitefish 1980 1981 II*. Reset 1983 1982 1997 Factor 2 2002 2000 2003 IV. 2015

USGS 12 Cisco Spring Bottom Trawl Assessment Lake Superior, 1978-2015 Relative Biomass (kg/ha) 10 8 6 4 2 0 Biomass Trends 10 Bloater 8 6 4 2 0 1978 1980 1982 1984 1986 1988 1990 1992 1994 1978 1980 1996 1982 1998 1984 2000 1986 2002 1988 2004 2006 1990 2008 2010 2012 2014 1992 1994 1996 1998 Year 2000 2002 2004 2006 2008 2010 2012 2014 Cisco Bloater Relative Biomass (kg/ha) Year

USGS Spring Bottom Trawl Assessment Lake Superior, 1977-2014 Year Class Trends Cisco Bloater - possible 2015 year class?? Relative Density (fish/ha) Relative Density (fish/ha) 1000 800 600 400 200 0 70 60 50 40 30 20 10 0 Cisco Yearlings 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 Bloater Yearlings Year-class 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 Year-class??

Why the lack of Cisco recruitment? Change in predators are they being eaten? Change in their food supply are they starving? Environmental changes? Where is the bottleneck? Photo by National Geographic

Lake Superior Understanding cisco recruitment dynamics Lakewide, 2014: 19 billion, 787 / ha Lakewide, 2015: 35 billion, 1,459 / ha

2014 high ice cover, very slow spring warming 92% ice cover, 25 March 2014 Max ice cover % 100 80 60 40 20 Photo from UW-Madison, Data from Canadian Ice Service 0

2015 high ice cover, plus spring warming? 68% ice cover, 25 March 2015 Warmer spring temperatures? Better growth? Better survival? Photo from UW-Madison, Data from Canadian Ice Service Max ice cover % 100 80 60 40 20 0 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 2015

Conclusions- Nearshore Prey fish biomass has declined 84% since the early 1990 s Due largely to reduced abundance of cisco, bloater, whitefish, and smelt. Absence of strong cisco year class since 2003. Absence of strong bloater year class since 2005 Decline in year class sizes of smelt and lake whitefish since 2007

8.0 Lake Superior Deepwater Fish Community, 2001-2006 7.0 6.0 nearshore offshore Deepwater Sculpin 5.0 Kg / Ha 4.0 3.0 Bloater Siscowet Lake Trout 2.0 1.0 Cisco Kiyi LN Sucker 0.0 Lean Lake Trout <41 41-80 81-120 121-200 >200 Depth Bin, meters Burbot

8.0 Lake Superior Deepwater Fish Community, 2008-2012 7.0 6.0 nearshore offshore Kg / Ha 5.0 4.0 3.0 Deepwater Sculpin Siscowet Lake Trout 2.0 Kiyi 1.0 Bloater L Whitefish Pygmy Whitefish Lean Lake Trout 0.0 Smelt <41 41-80 81-120 121-200 >200 Depth Bin, meters Burbot

Conclusions- Offshore Principal species: Siscowet, DW Sculpin, Kiyi; represents > 93% total biomass 3-5 times the biomass of Nearshore waters Deepwater biomass increased between 2001-2006 and 2008-2012 Increased biomass of kiyi: maturing 2003 year class Increased biomass of adult siscowet: maturity, growth Decreased biomass of deepwater sculpin: decreased density of adults,> 200 m; decreased density of all sizes <161 m depth

Conclusions Nearshore and offshore fish communities distinct Show different trends; biomass of nearshore community at lowest point in 35 years Offshore community more stable, much higher biomass Offshore community is the dominant community in Lake Superior; occupies ~77% of the lake by area, represents >90% of total fish biomass

Acknowledgments LSBS scientists (since 1957) Bill Dryer, Dick Pycha, J. Beil, J. Rahrer, Merle Bailey, Jim Selgeby, Chuck Bronte, Don Swedberg, Gary Curtis, Michael Hoff, Owen Gorman, Jason Stockwell, Daniel Yule, Mark Vinson R/V Kiyi crew, Joe Walters, Keith Peterson, Mike McCann, and Chuck Carrier USGS technicians Dan David, Joan Bratley, Gary Cholwek and Lori Evrard The many Northland College students that contributed to collection of fish, sample work up, and data entry since 1957! Supporting agencies and cooperators USGS USFWS USEPA Minnesota DNR Wisconsin DNR Michigan DNR OMNR DFO-Canada GLFC LSTC GLIFWC CORA etc.