Episode 106: Invasion of the Sea Lamprey?

Written, Produced, and Edited by Ruth D. Dan & Zaira G. Luján

Full Transcript of Podcast

In this episode of HearUR, Ruth and Zaira explore the environmental history of the Erie Canal through the lens of invasive species. Over the past two hundred years the Erie Canal, and canal systems that came after it, reorganized the shape and biodiversity of the Great Lakes ecosystems.The Sea Lamprey was emblematic of this transformation. As humans created new transportation routes through the engineering the of the region’s hydrology, they also made it easier for other animals to navigate the same waterways.  So-called “invasive species,” like the Lamprey, disrupted “native species” like trout, and their ability to reproduce. And as those native species declined, so too did the economic activity of the people who depended on them. More broadly, as the lakes’ economic fortunes spiraled downward, the lamprey was increasingly blamed as the primary cause. These two stories — creating new migration paths and the changing economics of natural fisheries resources — raise important question about what makes a species ‘natural’ or ‘alien.’

Poster for the 2014 Horror Film Based on Killer Lampreys [15]

The sea lamprey (Petromyzon marinus) is a parasitic fish that looks like a sock puppet of horrors. Lampreys are even horrifying enough to warrant their own low-budget horror flick, the 2014 film Blood Lake: Attack of the Killer Lamprey. The adult sea lamprey has a eel-like body, a sucker shaped mouth and no jaw. The lamprey latches on to a fish and grinds off the fish’s skin with circular sets of teeth. The lamprey then proceeds to suck out the host’s bodily fluids for sustenance, a practice called hematophagy. [1] A substance called lamphredin (secreted by the lamprey’s mouth) prevents the victim’s blood from clotting.

The sea lamprey is an anadromous species like salmon. Sea lampreys spending about a year in the ocean, attaching to large fish and sucking out their bodily fluids before returning to freshwater streams and rivers to spawn. Unlike salmon that return to the streams where they were born, sea lampreys migrate to freshwater streams following pheromones released by lamprey larvae (ammocetes). Newly spawned lampreys then spend the initial stages of their lives in the streams, maturing for several years before migrating back out to the open ocean. Like most anadromous species, sea lampreys can adapt this life cycle to a strictly freshwater environment. [2]

This is the case in the Great Lakes, and many of the lakes in New York State such as the Finger Lakes. It is difficult to establish just how long sea lampreys have been in these lakes — and therefore how ‘native’ it is. However, sea lampreys were likely introduced to these lakes through canals. The Erie Canal was a groundbreaking endeavor that represented an important shift in ecological boundaries, a shift that would not come to full fruition until a full century later. Sea lampreys were likely introduced to Lake Ontario through either the Erie Canal or the St. Lawrence Seaway. The Erie Canal might have also introduced lampreys to the Finger Lakes. Supporters of this theory argue that the lack of recorded sightings of sea lampreys in Lake Ontario suggest that Atlantic lampreys were introduced to the lake and adapted to that environment. Others, such as Dr. John Waldman with the Hudson River Foundation, have argued that sea lampreys are native to Lake Ontario and Lake Champlain. Waldman’s research team have conducted mitochondrial DNA studies that found Great Lakes lampreys and Atlantic Ocean lampreys have significant differences in mitochondrial DNA. [3] However, sea lamprey travel between Lake Erie and Lake Ontario is blocked by the Niagara Falls, and it was only after the lakes were connected through the Welland Canal that sea lampreys were able to populate the upper Great Lakes.

“Article, Commons Passes Bill Declaring War on Lampreys” from the Great Lakes Fishery Commission [16]

Because sea lampreys are not native to the upper Great Lakes, the fish species there like lake trout or lake whitefish have not evolved to survive lamprey predation. Due to this high mortality rate, sea lampreys became a predator in the Great Lakes rather than a parasite; parasites need their hosts to survive in order to secure both a short and long term future for the parasite. The 1954 Convention on Great Lakes Fisheries created the Great Lakes Fishery Commission. The Great Lakes Fishery Commission is made up of eight states (Michigan, Pennsylvania, New York, Ohio, Minnesota, Wisconsin, Indiana, and Illinois) , the Province of Ontario, and fifteen U.S. tribal nations (represented by the 1854 Treaty Authority, the Great Lakes Indian Fish and Wildlife Commission, and the Chippewa-Ottawa Resource Authority). According to the commission’s website, the commission was created primarily to control sea lamprey populations that had been introduced into the upper Great Lakes. [4] Sea lamprey control was considered an issue too big for any one agency to tackle alone, and the crashing fisheries populations in the 1950s put pressure on the managing bodies to work together. The technique primarily used by the commission to control lamprey populations and protect native species like lake trout is lampricide — poison. The commission currently uses a method known as “integrated pest management,” which attempts to limit the effect on non-target species while slowing lamprey adaptation to the toxics. [5] Lampricides do not only harm lamprey larvae, but if used improperly aquatic invertebrates and insects as well.

Although the sea lamprey is more lethal to the fish in the Great Lakes than the Atlantic Ocean, the use of lampricides shows the environmental story is still quite complex. The rapid decline in Great Lakes fish populations in the 1950s cannot be explained by the sea lamprey alone. The first recorded lamprey in Lake Ontario was in the 1850s. The first recorded lamprey in Lake Erie was in 1921; in Lake Huron in 1932; in Lake Michigan in 1936; and in Lake Ontario in 1946. Considering the lamprey was present in multiple lakes decades before the crash, the devastating effects of the lamprey should have been recorded earlier. In Sustaining Lake Superior, historian Nancy Langston establishes the other big player in the population crash: pollution. The use of industrial chemicals, pesticides, and heavy metals mining in the Great Lakes region rapidly expanded beginning in WWII to meet the demands of a new economy. [6] In the early 1900s, a scientist named Charles H. Stoddard lead a task force that provided a scientific basis for the claim that taconite (an iron ore) tailings deposited in Lake Superior was limiting the growth of Diporeia zooplankton, a base part of the lake’s food chain and proving that the lamprey alone were not initiating the decline. [7] Additionally, fish near the top of the food chain, such as lake trout are vulnerable to bioaccumulation of toxic chemicals. One family of chemicals, dioxins, are a byproduct of herbicide production. At 100 parts per trillion of dioxins, all lake trout larvae die. Dioxins were first detected in Lake Ontario in the 1930s, and between 1950 and 1975, dioxin levels were well above 100 parts per trillion in the lake.[8] This means that all lake trout larvae were poisoned by industrial pollution during this period, the exact period during which the decline of fish populations are blamed on sea lampreys. Furthermore, many other chemicals that affect fish life cycles including PCBs, DDT, and phenols have been detected in the Great Lakes.[9] Clearly, the sea lampreys and invasive species are not the entire story behind fisheries management in the Great Lakes.

The sea lamprey earned its reputation as the only managed species out of 180+ invasive species in the Great Lakes because of its threat to commercial, tribal, and recreational fishing which as a high economic value for local Great Lakes communities. The Great Lakes fisheries were viewed as inexhaustible resources by fisherman for decades. Attention was only truly brought to bear on the sea lamprey after fish populations, particularly lake trout, utterly collapsed in the 1950s. This marked the beginning of the concept of ‘invasive,’ ‘non-native,’ or ‘alien species’ in the Great Lakes region. Executive Order 13112 defines an invasive species as “(1) non-native (or alien) to the ecosystem under consideration and (2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” [10] As historian Andrew Cockburn details, invasive species gained traction as a concept in the early 1990s, as a way for scientists and policymakers to establish which species are harmful and which species are not. [11] Although species that have existed in an ecosystem for an extended period of time (native species) are often seen as inherently better, the aggression at which invasive species are destroyed and removed from the environment often depends on the economic or health costs of that invasive species.

Old Electrical Sea Lamprey Barrier

The Connecticut Department of Energy and Environmental Protection and the Nature Conservancy are even reintroducing to streams and rivers on the Atlantic where they have been extirpated (removed from the local environment). After spawning, adult lampreys die and their decaying bodies provide food for the basis of river ecosystems: aquatic insects.[12] Larval lampreys also filter feed, improving water quality. [13] As long as fish have co-evolved to survive lamprey predation, lampreys are a good part of river ecosystems.

Sea lampreys also exist in interaction with other introduced or non-native fish species. Another species that was introduced to the Great Lakes through the canal system is the alewife. Alewifes are not the target of an eradication campaign because they now serve a prime economic use: alewifes serve as the food needed to sustain a sport fishery of Pacific salmon, which are also introduced species. [14] The sea lamprey might have been native to the St. Lawrence Seaway, Lake Champlain, and Lake Ontario, but because the large native species (lake trout and Atlantic salmon) in those waterways have been extirpated, the designation of ‘native’ is moot. Lampreys kill too many of the economically viable species in those waters, so the Great Lakes Fishery Commission pursues suppression of those species anyways, whether the lamprey is ‘native’ to those waters or not.

Sea lampreys are viscerally revolting, and therefore easy to paint as a villain. Yet without a proper understanding of the context of sea lampreys in environmental history, lampreys can often become a red herring. Historians, the public, scientists, fisheries managers, wildlife and resource policy makers all have a responsibility to develop a holistic and comprehensive understanding of our effects on the Great Lakes and New York state aquatic ecosystems. The expansion of publicly funded canals such as the Erie Canal and the Barge Canal was fueled by a hunger for interstate commerce, a hunger that ramped up the possibilities for species to migrate into new areas and cause powerful changes in natural ecosystems such as the Great Lakes. Moving out of the canal expansions of the 1800s and into the increase in industrial and mining activity around the Great Lakes in the mid-1900s meant that humans now had an unprecedented effects over the Great Lakes fisheries, whether those effects was purposeful or not. These effects lead to new ways for society to approach and understand the aquatic environment. The Great Lakes became a managed and regulated resource on an ecosystemic level, with unprecedented management cooperation between formerly uncooperative organizations while the concept of invasive species gained new prominence to explain the need for aggressive assault and control of organisms formerly deemed acceptable by fishermen and scientists.



[1, 2] U.S. Fish and Wildlife Service. “ Sea Lamprey: Petromyzon marinus Linnaeus 1758.” Last modified January 2004. Accessed December 15, 2017.  https://www.fws.gov/GOMCP/pdfs/lampreyreport.pdf.

[3, 12] Williams, Ted. “Recovery: Why Sea Lampreys Need to Be Restored and Killed.” The Nature Conservancy: Cool Green Science. Published Dec. 11, 2017. Accessed Dec. 11, 2017. https://blog.nature.org/science/2017/12/11/recovery-why-sea-lampreys-need-to-be-restored-and-killed/.

[4, 5] Great Lakes Fishery Commission. “Sea Lamprey: A Great Lakes Invader.” Accessed December 15, 2017. http://www.glfc.org/sea-lamprey.php.

[6, 7, 8, 9] Langston, Nancy. Sustaining Lake Superior. Connecticut: Yale University Press, 2017.

[10] U.S. Department of Agriculture: National Agricultural Library. “What is an Invasive Species?” Last modified May 24, 2016. Accessed December 17, 2017. https://www.invasivespeciesinfo.gov/whatis.shtml.

[11] Cockburn, Andrew. “Weed Whackers: Monsanto, glyphosate, and the war on invasive species.” Harper’s Bazaar.

[14] Great Lakes Fishery Commission. “Managing the Lake Huron Fishery.” Accessd December 18, 2017. http://www.glfc.org/eforum/article3.html.

[15] “Blood Lake: Attack of the Killer Lampreys (TV Movie 2014).” IMDb, IMDb.com, www.imdb.com/title/tt3723790/. Photograph.

[16] “Article, Commons Passes Bill Declaring War on Lampreys.” The Great Lakes Fishery Commission. Photograph.

[17] “Old Electrical Sea Lamprey Barrier.” The Great Lakes Fishery Commission.



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