Background: The waters of the Mohawk River and its tributaries are inhabited by some of the most diverse fish communities in the Northeast. The construction of the Erie Canal in 1825, and later the Barge Canal in 1918, enabled the westward expansion of fishes from the Hudson River drainage as well as the eastward expansion of fishes indigenous to the Great Lakes drainage. Today, almost half of the fish species in the Mohawk River are nonnative (Carlson and Daniels, 2004) and George et al (2016), yet the fish community still fulfills many important economic and ecological functions. The Round Goby (Neogobius melanostomus) is an invasive benthic fish indigenous to Ponto-Caspian region of Eurasia that is invading eastward into the Mohawk River Basin through the Barge Canal. Introductions of Round Goby have had profound impacts on fish communities in the Great Lakes region and other areas (Kornis and others, 2012). Round Goby have the potential to outcompete native benthic fish species, reduce the recruitment of desirable gamefish through egg predation, and increase biomagnification of contaminants to higher trophic levels (Corkum and others, 2004). In regions with a temperate climate, Round Goby populations have expanded rapidly due to their ability to spawn multiple times during the warm-water season. For example, over a two-year period, Round Goby populations in Oneida Lake, NY increased from barely detectable levels to the most abundant benthic fish in the lake. Similarly, Round Goby colonized all five of the Great Lakes over a five-year period (Corkum and others, 2004).
Round Goby populations will likely continue their population expansion eastward throughout the Mohawk River/Barge Canal. To date, one specimen has been captured in the watershed of the Mohawk River (Utica, NY, September 2014, New York State Museum, catalog# 71439) and it is likely that a spawning population already exists in this section of the canal-river system. If the eastward (downstream) expansion continues as anticipated, Round Goby may enter the Hudson River shortly. From this point, they could be expected to move downstream throughout the tidal portion of the Hudson River and upstream through the lock system on the upper Hudson River and into the Champlain Canal, ultimately entering Lake Champlain. The Lake Champlain Committee recently identified Round Goby as one of the greatest new threats facing the lake and some have advocated for the closure of Champlain Canal to prevent this introduction. Additionally, Round Goby have recently been captured in high densities in small and mid-sized streams in the Great Lakes drainage (personal communication, Jeremy Wright, New York State Museum Ichthyology Laboratory), suggesting their populations also have the potential to colonize many tributaries to the Mohawk and Hudson Rivers, as well as Lake Champlain.
The 2012-2016 Mohawk River Basin Action Agenda has identified conserving fish, wildlife, and their habitats as a top priority. A Fisheries Management Plan for the Lower Mohawk River (McBride, 1994) is the most comprehensive document concerning the status of and challenges facing the Mohawk River fishery. One of McBride’s management recommendations is to “initiate fish studies based on specific needs as they may arise.” The rapid invasion of Round Goby into the Barge Canal has produced a pressing need to monitor the limits of their distribution, their population densities, and their effects on resident fish assemblages of the Mohawk River. Natural resource managers of the Mohawk River, Hudson River, and Lake Champlain may all benefit from quickly disseminated information concerning the expansion and potential impacts of this species.
Objectives: The primary objective of this project is to characterize the expansion of the Round Goby population in the Mohawk River/Barge Canal between over the next three years. A related goal is to devise long-term strategies to monitor the distribution and relative abundance of Round Goby throughout the Mohawk River, its tributaries, and connected water bodies. This secondary goal will be achieved by evaluating the efficacy of environmental DNA (eDNA) compared to traditional fish sampling methods to assess the presence/absence and relative abundance of Round Goby populations.
Approach: The objectives of this project will be met by regularly assessing the density and distribution of Round Goby populations across the river-canal system over a three year period using (1) a combination of minnow traps, seines, and trawls, and (2) eDNA analysis of water samples. Minnow traps provide a quick and effective assessment of presence/absence (Nett and others, 2012), but they do not produce quantitative data. Seines and trawls are more labor intensive, but they provide semi-quantitative measures of the abundance fishes occupying shallow and deep benthic habitats, respectively. Environmental DNA is emerging as a powerful screening tool for determining the presence/absence of both invasive species such as Asian Carp (Jerde and others, 2011; Jerde and others, 2013) and endangered species such as eastern hellbender (Olson and others, 2012) because it is typically effective even at low population densities.
Together, the four sampling techniques will provide a robust assessment of Round Goby populations as well as information on other benthic fish species which have not been thoroughly assessed since the early 1980s. The adaptive sampling program is structured for two discrete, intensive sampling efforts (spring and late summer) each year (2016-2017). The first of these efforts (spring 2016) will be conducted using all four sampling techniques at 8-12 sites along the Barge Canal starting just east of Oneida Lake and ending just upstream of Lock E6 at the Waterford Flight. After this initial sampling event, the types of gear and sampling regime will be reevaluated and modified if needed in order to most efficiently meet project objectives.
Project Location by County
Greene County, NY, Albany County, NY, Delaware County, NY, Fulton County, NY, Hamilton County, NY, Herkimer County, NY, Oneida County, NY, Lewis County, NY, Madison County, NY, Montgomery County, NY, Fulton County, NY, Schenectady County, NY, Saratoga County, NY
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“The catch from a seine-pull on the Mohawk River”
“Two round goby from the Barge Canal near Sylvan Beach, NY”
“A baited minnow trap being lowered into the water”
“Environmental DNA filtering”
“Pulling a seine on the Mohawk River”