Assessing the Distribution of Sea Lampreys (Petromyzon marinus) in the Hudson River Watershed
Thomas M. Evans
SUNY College of Environmental Science and Forestry
Final Report to the Edna Bailey Sussman Foundation 2013
Background
Anadromous fishes, i.e., those species that spawn in freshwater but migrate to marine ecosystems for the majority of their growth, are important members of many coastal ecosystems. The historic abundance of anadromous fishes, combined with their ease of capture during spawning migrations, has provided economic and social opportunities for numerous societies. Early European settlers, familiar with migratory fishes, were still impressed by the abundance and diversity of species that greeted them upon their arrival to North America. However, after initially utilizing these vast resources, Europeans rapidly overexploited the fisheries, while simultaneously limiting access to and destroying the freshwater habitats upon which anadromous fishes depended.
The Hudson River estuary watershed (HRE) is a biologically diverse ecosystem which currently contains nine anadromous fish species in its total of over 200 recorded species. The anadromous fish community in the HRE has been, in general, well studied. However, research efforts have not been evenly divided among all species, and gaps in the current understanding of this important group remain. Within this group, sea lampreys (Petromyzon marinus) are the most poorly studied member of the Hudson River anadromous fish community. Sea lampreys were neglected because they were not considered economically or socially important in North America, are often difficult to sample effectively, and perceptions about this species have been dominated by research efforts on invasive populations – as well as public perception – in the upper Great Lakes.
Sea lampreys belong to the most primitive group of vertebrate lineages (Order: Cyclostomata), and employ an anadromous, semelparous (i.e., a species that spawns only once) life history. However, unlike most other anadromous fishes, which spend a shorter time in fresh than in the marine waters, sea lampreys spend protracted periods in freshwater (up to 17 years) before a relatively brief time at sea (1-3 years). In addition, unlike many other anadromous fishes in the Northeast where at least some adults spawn more than once, sea lampreys always perish after a single spawning event. Because of the limited information available, there is no way to know historical abundance, or which streams were utilized by sea lampreys prior to large scale habitat alteration by European settlers. Even recent records of sea lampreys (i.e., those within the last 100 years) are difficult to find, and are often anecdotal.
Although sea lampreys have not often been considered an important member of the anadromous fish community, they may provide or have provided many of the same ecosystem services as other anadromous species. Sea lamprey larvae spend long periods in freshwater and contributions from the bodies of spent adults may have provided important food other animals. In Maine, sea lamprey spawning coincides with first feeding of salmonid juveniles, and spent adults, eggs, and embryos of sea lampreys may all provide important marine derived nutrients to these young salmonids. In addition, sea lampreys continue to spawn after other anadromous species during the spawning run; a sea lamprey adult was observed at a spawning site as late as June 26th during the course of this study. Finally, sea lamprey body shape and swimming style are unlike any other anadromous species, and they may prefer habitats not utilized by other anadromous species. In the upper Great Lakes, where sea lampreys are invasive, barriers are designed that specifically exploit their climbing style and exclude them from upstream reaches.
Therefore, this study addressed the need to establish the current distribution of sea lampreys in the Hudson River. Knowledge of their location will help to both to understand how these populations are responding to human alterations, what services they may be contributing, and provide potential avenues for restoration. The work in the present study is also timely as climate change further alters habitats and modifiesthe ranges of sea lampreys.
Sampling Sites
I sampled 22 tributariesof the Hudson River estuary below the Troy Dam for sea lampreys in the summer of 2013 (Figure 1). The sites chosen were based upon New York State Department of Environmental Conservation (NYSDEC) recommendations, as well as published, and anecdotal reports of sea lampreys (Table 1). The sites sampled from north to south are as follows: Poesten Kill, Normans Kill, Vloman Kill, Vlockie Kill, Muitzes Kill, Hannacroix Creek, Coxsackie Creek, Stockport Creek, Catskill Creek, Roeliff Jansen Kill, Saw Kill, Rondout Creek, Indian Kill, Black Creek, Quassaick Creek, Moodna Creek, Indian Brook, Annsville Creek, Cedar Pond Brook, Minisceongo Creek, Furnace Brook, and the Croton River. Sites varied widely in the predominant land use within their watershed, but sampling always occurred in areas with freshwater, preferably above the head of tide. If access could only be found below head of tide, sampling occurred there instead.
Methods
Surveys for Sea Lamprey
At 19 of these sites a full workup was performed, while at the remaining three only sampling for sea lampreys was performed. A full workup included measuring local habitat characteristics, physical and chemical sampling of the stream, a macroinvertebrate sample, and a survey for sea lampreys at the site. In those sites where a full workup was not conducted, conditions were determined to be extremely unlikely to support lampreys, usually because of siltation or high water temperatures. However, to validate the expectation, sampling for lampreys was conducted in the same manner as at all other sites. I also interviewed individuals who visited the site during sampling. Any pertinent information they provided to the study was noted.
To determine the composition of the surface area of the sampled stream reach, a diagonal transect across the stream from bank full to bank full was walked. At every step along the transect two points were randomly selected and the bottom composition was determined following the NYSDEC bottom composition scale for at least 100 points (NYSDEC 2009). If a transect was too short to sample 100 points, a second transect was set and the process repeated.
Aquatic macroinvertebrate samples were collected by sampling the nearest riffle to the sample site, walking along a 5 m diagonal transect, and kicking into a D-frame net. The entire sample was immediately placed in 70% ethanol and stored at ambient temperature. Upon return from the field invertebrates were picked from detrital material and classified.
To determine if sea lamprey were present at a site I used a backpack electrofisher (Haltech, HT-2000) to electrofish for larval lampreys (Figure 2). A low shock (5 Hz, 150 V, 2:2 pulse pattern) was used to cause larval lampreys to emerge from the substrate. Animals that emerged where captured before they could burrow. The weak pulsed electrical output encouraged larval lampreys to emerge and attempt to burrow rapidly, in contrast to a continuous pattern which generally caused them to forgo burrowing and attempt to escape the electric field or remain burrowed. I electrofished for 15 minutes at each site, which allowed the sampling of all habitats that appeared likely to support sea lampreys.
Completed Work
I sampled at 29 sites and collected lamprey at 6 locations, which have been stored and are being prepared to be submitted to the New York Museum for archiving. One of the sites I collected at (below High Falls, NY on the Rondout) was the first collection of sea lamprey on the stream since 1934. I also worked through 20 invertebrate samples, identifying over 2000 individuals to genusand many more to order. I also had the opportunity at three sites (Catskill, Cedar Pond Brook, Roeliff Jansen Kill) to traverse large sections of streams to get a better idea of how sea lamprey are distributed within this habitat. The work completed to date defines the distribution of sea lampreys in the Hudson River for the first time, and establishes a baseline for future research. Finally, in addition to the results presented herein, work was also completed to understand the food sources of larval lampreys through a grant from the Hudson River Foundation.
Results
I found sea lampreys in four tributaries of the Hudson River: the 1) Roeliff Jansen Kill (Columbia County, confluence at river km 178), the 2) Catskill (Greene County, river km 182), 3) Rondout Creek (Ulster County, river km 146), and 4) Cedar Pond Brook (Rockland County, river km 63; Figure 1). Sea lampreys were not found in all rivers for which prior records of these animals existed (Table 1).
Sea lamprey presence was not correlated with percent bottom cover (i.e., percent cover of rock, rubble, gravel, sand, or silt), percentage of caddisflies, stoneflies, flies, or midges in the invertebrate sample. Nor were they correlated with the species richness, the SDI, or the HBI for invertebrate samples. Although it was not significant, sea lampreys were never found at sites that did not also have stoneflies, and they were associated with sites that had a high percentage of mayflies.
The average length of YOY larval lamprey was different between sites. The Roeliff Jansen Kill YOY larval lamprey were larger ~10 mm larger (28.8±3.5 mm, SD) than larvae from all other sites (18.8±2.6 mm, SD; Figure 3).
Present Findings
Sea lamprey presence/absence was associated with only a few of the metrics I collected. These results are consistentwith prior work that has found that sea lamprey distribution at the site level difficult to predict from in-stream habitat data. However, to my knowledge this was the first to attempt to link invertebrate and lamprey data. Sea lamprey larvae utilize habitat in the hyporheic zone (i.e., area along the edge of the stream in which ground and surface waters mix) potentially limiting the usefulness ofgross site level characteristics to predict their distribution. Subsurface flows, ground water temperature, and oxygen content may all play important roles, but are difficult to measure and scale up.
The metrics collected on macroinvertebrates did not provide statistical measures to determine if sea lampreys were present or not at a site. Nevertheless, macroinvertebrate qualitative measures were still useful for evaluating a site’s suitability for sea lamprey. Sea lampreys are intolerant of many types of pollution, as are many invertebrates, which are easier to collect and more abundant. Habitats with a diverse invertebrate fauna, including stoneflies and abundant mayflies, were always associated with sea lamprey. Sea lampreys were never found in areas with low invertebrate diversity or where these two sensitive groups were absent. These classifications (only to Order) are easy to do in the field in a matter of a few minutes and require no special equipment to collect.These observations may help provide restoration efforts a way to evaluate the feasibility of a site for supporting sea lampreys.
In an effort better to understand lamprey distribution, I electofished long lengths (>1 km) of three streams to better understand how lampreys were distributed. Larval lampreys were often located immediately downstream of habitat appropriate for adult spawning activities. Even though appropriate habitat for larval lampreys was available at different locations in other sites in the stream, the restriction of larval lamprey to only certain areas provides insights into their colonization of new habitats.
Conclusions
The distribution of larval lampreys in the Hudson River is restricted to only a few tributaries (i.e., Cedar Pond Brook, Catskill, Roeliff Jansen Kill, Rondout Creek). Worryingly, I found sea lampreys in fewer locations in the Hudson River than have been reported in the past. However, many of the reports are for adult animals, which were likely seeking suitable spawning habitat and are not as sensitive as larvae. In at least one case (i.e., Stockport Creek), there appears to be a true reduction in their range. Sea lampreys may be able to make rare successful spawning events in this stream that produce larvae for extended periods, but attract easily visible adults for long periods. The barriers to migration at Stockport Creek would be difficult for sea lamprey to pass except during exceptionally high flow years. Animals unable to penetrate above the falls and dams likely do not produce larvae, but any adult that made it upstream would have excellent habitat available for spawning and the subsequent larvae.
Currently in the Hudson River the Catskill is the most important producer of sea lamprey, and the Kaaterskill Creek (which is a tributary to the Catskill) is its most important tributary. The Kaaterskill Creek has a long stretch of (>10 km) of unobstructed habitat appropriate for both sea lamprey larvae and adults, making this unique to the Hudson River. The Roeliff Jansen Kill is also an important tributary for sea lamprey in the Hudson River. Sea lampreys in the Roeliff Jansen Kill may grow more quickly than at any of the other tributaries where they were captured (Figure 3). More work is needed to determine if growth rates are actually higher throughout the Roeliff, or if larval growth is more dependent on local conditions.
Sea lampreys prefer cool water, and as a result climate change is likely to restrict and reduce sea lamprey numbers in the Hudson River. Although climate change is a threat to the future of sea lamprey in the Hudson River, past human activities have also likely limited populations through the construction of dams and pollution of stream waters. However, sea lampreys in the Hudson River were likely never as abundant as other members of the migratory fish community. The erosion of decaying dams and the removal of barriers to migration may allow sea lampreys to exploit more habitats, potentially providing a buffer against climate change impacts. Sea lampreys are an unusual member of the Hudson River that have been little studied, but their uniqueness and importance as members of the anadromous fish community make them deserving of more directed research efforts.
This study was expanded upon by a separate grant from the Hudson River Foundation which allowed for work with stable isotopes to examine sea lamprey nutrition sources. The addition of these data provided an opportunity to produce a manuscript for publication, which will be submitted in 2014 to a peer-reviewed journal (Northeastern Naturalist). In addition, a blog ( was created and regularly updated to provide an opportunity to provide a permanent online record easily accessible to scientist and non-scientists alike. Finally, I will submit an abstract to present this work at the AFS New York chapter meeting in February 2014.
References
Bryan, M. B., D. Zalinski, K. B. Filcek, S. Libants, W. Li, and K. T. Scribner. 2005. Patterns of invasion and colonization of the sea lamprey (Petromyzon marinus) in North America as revealed by microsatellite genotypes. Molecular Ecology 14:3757-3773.
Greeley, J. R., and Greene, C. W. 1937. Fishes of the area with annotated list. A biological survey of the lower Hudson watershed. New York State Conservation Department, Supplement to the twenty-sixth annual report: Albany, NY.
New York State Department of Environmental Conservation. 2009. Standard operating procedure: biological monitoring of surface waters in New York State. Operating Procedure: Albany, NY.
New York State Department ofEnvironmental Conservation. 2012a. (accessed October 19 2013)
New York State Department ofEnvironmental Conservation. 2012b. (accessed October 20 2013)
Schmidt, R. E., and S. Cooper. 1996. A catalog of barriers to upstream movement of migratory fishes in Hudson River tributaries. Report of Hudsonia Limited to the Hudson River Foundation, New York.
Schmidt, R. E., and K. Limburg. 1989. Fishes spawning in non-tidal portions of Hudson River tributaries. Final report to the Hudson River Foundation, New York, NY.
Smith, C. L. 1985. The inland fishes of New York State. New York State Department of Environmental Conservation: Albany, NY.
Acknowledgements
I thank the Edna S. Bailey Sussman Foundation for funding and support of this project. I also thank Kathy Hattala and Robert Adams for advice and guidance on selecting locations and choosing streams to survey. In addition, thanks to all members of the NYSDEC who provided help and reports of sea lamprey, and especially to those working on the Hudson River Almanac. Thanks also to David Yozzo who allowed me to come field sampling with him and for providing information. Special thanks to John Waldman, Robert Schmidt, and Erik Kiviat for their help this summer. Thanks to Karin Limburg for her help and support throughout my work on this project, and for reviewing and editing drafts. Finally, thanks to Caitlin Eger, my wife, for all her help and for assisting in almost all of the field sampling for this project.