Journal of Great Lakes Research 38 (2012) 19 –34 Contents lists available at SciVerse ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr The history and future of Lake Champlain's fishes and fisheries J. Ellen Marsden a,⁎, Richard W. Langdon b,1 a Rubenstein School of Environment and Natural Resources, Aiken Center, 81 Carrigan Dr., University of Vermont, Burlington, VT 05405 USA b Vermont Department of Environmental Conservation, 103 South Main St., Waterbury, VT05671-0401, USA article info abstract Article history: In the last two centuries, physical, chemical, and biological alterations of Lake Champlain have resulted in the Received 11 January 2011 loss of two species, addition of 15 fish species, and listing of 16 species as endangered, threatened or of spe- Accepted 7 June 2011 cial concern. The lake currently supports 72 native fish species; lake trout ( Salvelinus namaycush) and Atlantic Available online 29 November 2011 salmon (Salmo salar) were extirpated by 1900, American eel ( Anguilla rostrata) and lake sturgeon ( Acipenser fulvescens) populations are extremely low, and walleye ( Sander vitreum) are declining. Dams on several rivers, Communicated by Doug Facey and ten causeways constructed in the mid 1800s to early 1900s, cut off access to critical spawning areas and fi Keywords: may have limited sh movements. Siltation and sediment loading from agricultural activity and urban growth Habitat fragmentation have degraded substrates and led to noxious algal blooms in some bays. A commercial fishery targeting Zoogeography spawning grounds of lake white fish ( Coregonus clupeaformis ), lake trout, and walleye probably reduced numbers Management of these species prior to its closure in 1912. Non-native species introductions have had ecosystem-wide impacts. Degradation Sea lamprey ( Petromyzon marinus ) populations were very high prior to successful control, possibly as a conse- Restoration quence of ecological imbalance and habitat changes. A paucity of historic survey data or accurate species accounts limits our understanding of the causes of current fish population trends and status; in particular, the effects of habitat fragmentation within the lake and between the lake and its watershed are poorly understood. Holistic, ecosystem management, including pollution reduction and examination of habitat impacts, is necessary to restore the general structure of native biological assemblages. © 2011 Published by Elsevier B.V. on behalf of International Association for Great Lakes Research. Introduction then discuss the consequences for management of the fisheries and protection of fish populations and communities. Following the European discovery of Lake Champlain in 1609 by its namesake, Samuel de Champlain, the ensuing 400 years brought Description of Lake Champlain substantial physical changes to the watershed, lake sediments, and hydrological connections within the lake. Two fish species, lake Lake Champlain is a long (193 km), narrow (20 km at its widest trout2 and Atlantic salmon, were extirpated, 15 fish species were point) lake that lies on the border between New York and Vermont, added, and 16 fish species have been listed as endangered, threat- extending into Quebec at the north ( Fig. 1). The lake averages ened, or of special concern/susceptible. Chemical inputs from land 19.5 m depth, with the deepest portion (122 m) in a narrow trench use and industries have caused algal blooms and have contaminated immediately south of the main basin. Three long islands split the fish tissue. These changes in the biological, physical, and chemical char- northern third of the lake into eastern and western arms; causeways acteristics of the lake present practical and philosophical challenges to constructed among these islands and between the islands and the management: to what extent have ecosystem services been compro- mainland have further divided the lake. Currently five distinct basins mised, is restoration possible, and should restoration, rather than ac- are recognized: Missisquoi Bay at the north is shallow (4.3 m maxi- ceptance of an altered system, be the goal? Herein, we review the mum depth) and highly eutrophic, the Northeast Arm (locally called history of biological and physical changes in the lake and the subse- the Inland Sea) and Malletts Bay to the east are moderately deep quent changes in the stability and distribution of fish populations. We (48 and 30 m, respectively) and mesotrophic; the Main Lake, com- prising the broad lake and northwestern arm, is largely deep and oli- gotrophic, and the South Lake is eutrophic and largely riverine (Marsden et al., 2010 , Fig. 1). The watershed is large (21,326 km 2) ⁎ Corresponding author. Tel.: +1 802 656 0684; fax: +1 802 656 8683. in relation to the lake area (1130 km 2), so that anthropogenic uses E-mail addresses: [email protected] (J.E. Marsden), of the landscape have the potential to signi ficantly impact the lake. [email protected] (R.W. Langdon). Vermont, New York, and Quebec contain 56%, 37%, and 7% of the wa- 1 Tel.: +1 802 734 6498. 2 All scientific, current, and historic common names of fish species present in Lake tershed, respectively; 62% of the lake surface area is in Vermont, 34.5 Champlain and mentioned in this paper appear in Table 1. in New York, and 3.5% in Quebec. The lake receives input from 0380-1330/$ – see front matter © 2011 Published by Elsevier B.V. on behalf of International Association for Great Lakes Research. doi:10.1016/j.jglr.2011.09.007 20 J.E. Marsden, R.W. Langdon / Journal of Great Lakes Research 38 (2012) 19 –34 Fig. 1. Lake Champlain, showing major rivers, lake segments, and towns mentioned in the text. The two Vermont dams, at Milton and Swanton, are indicated with stars. Inset indicates the location of the two dams on the Richelieu River, and the canals that link Lake Champlain with the Hudson and Mohawk rivers to the south, and bypass the rapids on the Richelieu River to the north. numerous tributaries; the 11 major rivers each drain from 2252 to Mississippian refugium diffused northward and eastward into the pro- 3500 km 2 of watershed. The outlet to the lake is the Richelieu River, glacial Great Lakes ( Schmidt, 1986 ). Lake Vermont was connected to which flows into the St. Lawrence River from the north end of the the outlet of the Great Lakes that ran to the Atlantic Ocean, first through lake. The Chambly Canal, opened in 1843, bypasses the rapids on the Mohawk and Hudson Valleys, then through the St. Lawrence Valley the Richelieu River. The Champlain Canal, opened in 1823, connects (Fig. 2 ; Langdon et al., 2006 ). Fishes also entered meltwater rivers and the lake to the Hudson River drainage and to the Great Lakes via the lakes to the south from unglaciated areas along the mid-Atlantic Coast New York State Canal System. into Lake Vermont via the connection with the Hudson River Valley (Schmidt, 1986 ) and possibly via the outlet of Lake Winooski into Physical history of Lake Champlain the Connecticut Valley ( Langdon et al., 2006 ). Between 13,000 and 10,000 years ago, migrations via freshwater connections from the St Beginning about 18,000 years ago, melting of the retreating Lawrence Valley were interrupted by the incursion of the Champlain Wisconcinan glacial ice sheet, the last in a series of glaciations, created Sea ( Cronin et al., 2008 ). vast proglacial water bodies across the North America ( Dyke and Following the eventual freshening of the Champlain Sea, access to Prest, 1987 ). In the wake of the receding glacier, fishes and other aquatic the lakes by Midwestern fauna was temporarily reestablished via the populations began populating glacial melt waters through connections Great Lakes outlet, the St. Lawrence River, that led to the Atlantic to glacial refugia located to the west, south and east of the shrinking gla- Ocean (Dadswell, 1972). This avenue was available for fish movement cier. Proglacial Lake Vermont filled the Champlain Valley with various until glacial rebound of the Champlain Valley floor created abrupt shorelines up to 183 m higher in elevation than present day ( Fig. 2 ; changes in gradient of the Richelieu River outlet at the north end of Chapman, 1937 ). In the Midwest, species originating from the rich the lake. The resulting waterfalls created barriers that prevented J.E. Marsden, R.W. Langdon / Journal of Great Lakes Research 38 (2012) 19 –34 21 natural access of fishes to the Champlain Valley from the St. Lawrence and Richelieu Rivers, leaving the existing native fauna that we see today. The completion of canals at the southern and northern ends of the lake during the early 1800s once again opened dispersal corri- dors to fish species, though fishes accessing Lake Champlain via these routes are now regarded as non-native ( Langdon et al., 2006 ). Currently, the principal fall line runs north–south on the Vermont side of the lake at an elevation of approximately 46 m. The fall line is characterized by precipitous drops in elevation of major tributaries; the resulting falls are barriers to most fish species. The area below the falls in these tributaries provides needed spawning habitat for many species such as walleye, lake sturgeon, and three redhorse spe- cies. In addition, these areas provide unique habitat for smaller spe- cies, many of which are rare, such as the eastern sand and channel darters, mottled sculpin, and stonecat. No similarly abrupt fall line is present on the New York side of the valley, where tributaries descend more quickly and steadily to lake level. Changes in the watershed Most of the Lake Champlain watershed was forested prior to European colonization; in the late 1800s up to 60% of the landscape was deforested, with additional land cleared at various times. Currently, the watershed is largely reforested in the Adirondack Mountains to the west and the Green Mountains to the east, with extensive agricultural areas in Vermont and Quebec.