The Great Lakes • Physical Aspects • Geologic Origin • Physical Features • Fish Community • Overview • Lake Trout, Whitefish and the Lamprey invasion
Surface area: 245,000 km2 Drainage basin: 753,950 km2 1 3 • Superior • Michigan • Huron • Erie • Ontario 5 2 4
>12,000 B.C. ~11,700 B.C. Lake Chicago Earliest lake Chicago Lake Arkoma Lake Maumee ~9,500 B.C. ~8,000 Lake Keweenaw Lake Chicago Lake Chicago Lake Warren The Great Lakes: glaciation
The Great Lakes: glaciation ~6,000 B.C. ~3,200 ~2,000 B.C Present
Bathymetry of the Great Lakes http://www.ngdc.noaa.gov/mgg/image/greatlakesimages.html
Morphoedaphic Index Regier and Schlesinger 1982 TAFS
Commercial fish catch, all species and all Great Lakes combined Kelso et al. 1996 CJFAS Suppl.
Great Lakes Fish Community Lake sturgeon • Native fauna: • 153 species • 64 genera • 25 families • Present (2002): • 179 species • 29 families Lake herring Blackfin cisco (Extirpated) Burbot
Distribution of offshore Great Lakes fishes(Eshenroder and Burnham-Curtis 1999)
Invasive species in the Great Lakes Alewife • Introductions: • 25 fish species: • 14 intentionally • 5 via canals • 6 accidental release or ballast water • Ashworth (1986) estimated that 95% of GL fish biomass was non-native species Rainbow smelt Round goby McCrimmon Jr. 2002 Lakes and Reservoirs: Research and Management 7:241-254 Bluespotted sunfish
Lake Trout (Salvelinus namaycush) • Spawn in fall in boulder or rubble reefs, shallow to 37 m • Mature at age 6-7 • Fecundity ~ 1,000-18,000 • Feed on alewife, smelt, sculpin and coregonids • Catches averaged about 6.8 million kg/yr (US + Canada) Mingeouk girl and Lake trout, Port Epworth c.1913
Lake trout (Salvelinus namaycush) courtesy Steve Geving, Minnesota DNR
Two of the lake trout phenotypes in Lake Superior: Siscowet lake trout live in deep water, grow slowly, and have such high lipid content that they are not valued in commercial fisheries Lean lake trout (the more prototypical lake trout) lives in nearshore waters of Lake Superior courtesy Mark Ebener, Chippewa-Ottawa Resource Authority
Siscowet feeding ecology The high oil content of the siscowet may function, in part, for buoyancy control. In very fatty ones, even the swim bladder is filled with fat. Although thought of as a deep water fish they seem to move up and down a lot. Siscowet have been caught 100 m down with such things in their stomachs as ants, ees, moths, sparrows and even a bat (!), indicating that they fed near or at the surface.
Lake trout often form “eco-phenotypes” with discrete morphology, diet, behavior, and distribution. The forms may be genetically distinct. Photos courtesy of Paul Bentzen, Dalhousie University
Lake Whitefish Coregonus clupeaformis) • Spawn in fall (Nov. and Dec. in GL), water <7.6 m, over hard, stony bottom or sand • Fecundity: 8,200-16,100 • Up to 19 kg (L. Superior 1912) and 17 years (oldest recorded: 28 yrs) • Planktivores, also eat small fish and mollusks (note slightly down-turned mouth)
Lake Whitefish • Great Lakes 1948 catch was 7.95 million kg • In the1850s people with a 10 x 300 ft beach seine could catch up to 40,000 fish in one night!
Sea Lamprey (Petromyzon marinus) • Anadromous lamprey of North America and Europe • Range: Florida to Newfoundland; Iceland to North Africa • Small landlocked populations: Lake Champlain, Finger Lakes, Lake Ontario? (Waldman 2004)
Sea Lamprey • Spawn in spring • Fecundity: 34,000 to 110,000 max: >200,000 • Eggs ~ 1 mm • Feeding by adults ceases prior to upstream migration • Eggs hatch in about 2 weeks; ammocoetes leave nest at 18-21 days (total). • Drift downstrem; burrow ~ 13 mm down into fine sediment ammocoete
Sea Lamprey • Ammocoetes filter-feed on algae, diatoms, detritus, protozoans • Transformation takes few weeks; migrate downstream in late fall • Teeth rasp a hole in skin of prey and body fluids are consumed • “Lamphredin” inhibits coagulation of blood • May penetrate body wall • Kill small hosts; weaken large ones
The ammocoete periods usually last 3 years in the Great Lakes but can be as long as 10 in less productive streams
Lake Champlain (flows north to the St. Lawrence) Erie Canal Hudson River (flows south to New York) 1823: Lake Champlain connected to the Hudson River 1825: Lake Erie connected to the Hudson River
Niagara Falls, a nice place to get married (?) but tough for navigation Also, a nice way to isolate the fishes in the upper Great Lakes from the lower part of the system
Sea Lamprey Invasion of the Great Lakes Superior 1938 St. Lawrence River Huron 1932 Ontario 1800s? Michigan 1934 Hudson River Erie Canal Erie 1921 Atlantic Ocean
Welland Canal: 1829, re-built 1914-1932. Connects Lake Erie and Lake Ontario St. Lawrence River Lake Ontario Hudson River Erie Canal: 1825, connects Lake Erie to the Hudson River Lake Erie Atlantic Ocean
What attracts lamprey to fish? In general, lamprey prefer to attack larger host fish rather than smaller ones, and fish with smaller (or no) scales are also more vulnerable. Thus heavily scaled fishes such carp, perch, and suckers are less often parasitized than burbot, catfish, and salmonids.
Large scales (yellow perch, top; white sucker, bottom) Small scales (lake trout, top; burbot, bottom)
Lake trout size and vulnerability to lamprey Swink 1990. Trans. Amer. Fish Soc. 119:996-1002
How do fish survive? • When lamprey attack a fish, they consume blood and body fluids and the fish takes on water. Thus the nutritional value of the fish declines for the lamprey and it may drop off if there are other fish in the vicinity. Troy Jaecks photo
Analysis of catch per unit effort(Coble et al. 1990. TAFS 119:985-995) • Coble et al. 1990 concluded that Huron and Michigan crashes can be attributed exclusively to lamprey but there is evidence that over-fishing in Superior was a contributing factor.
Populations of lake trout and sea lamprey in Lake Superior USGS UMESC, http://www.umesc.usgs.gov/invasive_species/sea_lamprey/tech_assistance.html
Sea Lamprey invasion • Lake Ontario – kept in check by some unknown force • 1870s lamprey caused problems in Finger Lakes of New York • Completion of the Welland Canal around Niagara Falls (44 km long; 8 locks) allowed invasion of the upper Great Lakes • Decreased lake trout to about 10% of their former abundance (virtually eliminated from all but Lake Superior) • With fishing, fewer large fish were available and small trout killed • Attempts to eradicate lamprey led to the Great Lakes Fishery • Commission (1955) • 1961 – peak lamprey population • Presently reduced to about 10% of the peak levels
TFM • TFM (3-trifluoro-methyl-4-nitrophenol), mechanical weirs, electric fences • TFM kills ammocoetes • First applied in Lake Superior 1958 • First success in 1962 when lamprey pop. 14% of 1961 pop. • 1962-1978 catches reduced from 4-21% of 1961 catch
Problems with TFM • TFM application is costly; will we always be willing to pay for it? • There are some mortalities to non-target fishes, and notably native parasitic lamprey species (chestnut and silver lamprey) that are of conservation concern. These native species co-evolved with the rest of the fish community and did not dominate it.
Lake Superior lake trout catches Catches in U.S. Splake = hybrid speckled (=brook) x lake trout Bronte et al. 2003 CJFAS 60:1552-1574
Lake Superior stocked lake trout Millions Stocked Bronte et al. 2003 CJFAS 60:1552-1574 Splake = hybrid speckled (=brook) x lake trout
Relative abundance (CPUE) of siscowet lake trout in the commercial gill-net fishery, Lake Superior Bronte et al. 2003 CJFAS 60:1552-1574
Relative abundance of wild and hatchery-reared lean lake trout in spring stock assessments in U.S. waters of Lake Superior Lean lake trout Wild Hatchery Bronte et al. 2003 CJFAS 60:1552-1574
Lake trout in nearshore commercial fisheries in Canadian waters lean and siscowet Bronte et al. 2003 CJFAS 60:1552-1574