Manmade Passage, Natural Consequences

The Welland Canal and Sea Lamprey Spread

Jenna Stroeder

Niagara - 2024

The construction of the first, second, and third Welland Canals were crucial to improving travel, trade, and distribution of goods on the Great Lakes. Inspired by the success of the Erie Canal following the War of 1812, British and American Loyalists recognized the need for a similar canal to facilitate navigation around Niagara Falls, which was at the time, a significant "distributing point for forts and settlements".¹ The construction of these canals, while they enhanced simplicity in travel and trade, would also eventually complicate the ecosystems within the Great Lakes upon the introduction of the very invasive species, sea lamprey. This essay aims to unpack the ways in which sea lamprey presence in the Great Lakes impacts existing species, as well as efficiency former efforts in sea lamprey control, a strenuous task which continues to this day. This essay focuses on the human role in the introduction of the sea lamprey to the Niagara Region and the ongoing ecological consequences of their presence and control measures. This paper will highlight the complex interplay between human infrastructure and environmental sustainability.

A St. Catharine's businessman by the name of William Hamilton Merritt proposed the concept of the Welland Canal as a means of improving industrial and urban development along the Great Lakes. Building the Canal was formerly deemed too difficult due to the risks posed by the Niagara Falls rapids, which prior to the erection of the first Welland Canal on November 30^th^, 1829 were completely impassible.² However there was a growing need amongst Canadians for accessible travel across the Great Lakes, specifically following the war of 1812 which had presented many risks to the safety of vessels and their passengers. The unsafe water frontier which directly faced American gunboats, as well as the construction of the American Erie Canal which ran from Buffalo to Albany, Canadians felt a push to build a canal of their own which would ultimately allow for safer passage by varying vessels would later assist in the national recovery from poverty following the war.³

The first Welland Canal, which acted as an essential passage for vessels between Lake Erie and Lake Ontario, local watercrafts found ease in avoiding the aggressive rapids of Niagara Falls. The Welland Canal went through many changes before becoming the structure that we know today. The Second Welland Canal (completed in 1845) was deemed necessary, as wooden locks became outdated and ships were built larger than the original locks could accommodate. The Second Canal "enlarged the Feeder Canal and made a connection to Port Maitland"; it remained in use until 1915.⁴ The Third Welland Canal opened in 1881 after six years of construction, it provided vessels with a shorter route between Lake Ontario and Erie. Similar to the previous designs, the rapid growth in ship-size resulted in the need for a larger canal only twenty years later. The third canal would remain in operation until the fourth and final Welland Canal, which we know today, opened in 1932.⁵⁶ Figure 1 indicates the layout of the most recent Welland Canal.⁷ The context of these staggered openings and movement of new vessels through new passageways is significant as they contributed to the gradual exposure of invasive sea lamprey to the Great Lakes.

Upon their initial introduction to the Great Lakes, sea lamprey (or their technical term, 'Petromyzon marinus') "have been the target of an intensive binational control program for over sixty years".⁸ The nature of sea lamprey's classification as invasive was due to their high-speed infiltration, and the hostile destruction of surrounding sea life which resided in the Great Lakes prior to their presence in the ecosystem (i.e., lake trout, northern pike, carp).⁹ Sea lamprey have round "suckermouths" with rows of sharp teeth, as seen in Figure 2.¹⁰ The suckermouths often latch onto fish, tearing holes in their flesh, then either inject a chemical which prevents blood clotting resulting in a continuous flow of blood with which lamprey satisfy their appetite, or leave the fish for dead. Many larger fish can be spotted with lamprey scars. On top of their disturbances to residing marine creatures, lamprey were reported to approach swimmers, though no injuries have ever been reported.¹¹ Sea lamprey are typically fifteen inches in length, and emulate the appearance of an eel. Their invasive nature stems from the fact that they rarely establish a home base but rather select spawning streams based on environmental cues which ultimately resulted in their obscure population structure.¹² Throughout their lifespan, sea lamprey experiences two phases: stream-resident phase and parasitic juvenile phase, "the latter [which] is responsible for such extensive damage to the Great Lakes."¹³

The introduction of sea lamprey to the Great Lakes is often attributed to man-made canals and the vessels that constantly travel through the waterways. In a 2021 research study on sea lamprey dispersal and control, the findings of Docker et. al emphasized that:

"Sea lamprey entered the Lake Ontario drainage no earlier than the 1860s through manmade canals...[they] were subsequently able to bypass Niagara Falls and disperse into Lake Erie and the remaining Great Lakes when the Welland Canal was completed in 1829."

The first recording of sea lamprey in the Great Lakes was in the 1830's, which highlights how Niagara Falls once acted as a blockade to the aquatic pests, however the natural barrier to this invasive species was circumvented by the creation of the Welland Canal system. Though beneficial to human travel, the Welland Canals were beneficial to sea lamprey travel, as they were recorded to have latched onto many of the vessels that passed through the canals, ultimately finding their way throughout the Great Lakes in a short period of time.¹⁴

By 1938, sea lamprey had been recorded in every Great Lake.¹⁵ The gradual spread of sea lamprey was not initially taken seriously by government officials, and in fact was paid little attention until each of the lakes continuously fell victim to the infestation. More and more Great Lakes native fish species were found with lamprey scars or dead, to which officials responded with a stronger sense of urgency regarding the purification of the lakes. Figure 3 indicates the point in which sea lamprey were located in each of the Great Lakes displays rate at which the species spread following the official opening of the Welland Canal.¹⁶ Each addition to the canal would impacted the number of fish able to pass through, as passageways widened and vessels grew. The final construction of Canal Four is said to be the likely cause of the eventual lamprey population detected in Lake Erie. Lamprey were native to the Atlantic Ocean, thus they had little to no purpose in the Great Lakes and often were only a disruption to existing ecosystems which do not include any natural predators toward sea lamprey. The ability to control the number of sea lamprey in the Great Lakes became increasingly urgent in order to regain and preserve the integrity of the Lakes and natural species.

Active efforts to eliminate the existing population of sea lamprey in the Great Lakes began in the late 1950's when the threat to existing ecosystems and fisheries was more evident. The Great Lakes Fishery Commission was formed in 1955 "with a primary mandate to formulate and implement a sea lamprey control program."¹⁷ During this time, a chemical known as a "lampricide" (or TFM) was developed in order to target sea lamprey populations. TFM was immensely effective in decreasing lamprey numbers and is still used in present-day prevention methods. This control chemical was highly effective and had the impressive ability to simultaneously remain unharmful to other environmental factors (i.e., water quality, plant growth, other fish). The Great Lakes Fishery Commission indicated that even "animals exposed to 500 times the typical treatment concentrations for extended periods of time showed no adverse side effects."¹⁸

Lampricides, however, were not the sole method of lamprey population control. Beginning in the 1970's, the "sterile-male release" technique came to light as a means to deplete the sea lamprey population gradually and naturally in the Great Lakes. With growing public concern regarding the sustainability of pesticides, there was a push for researchers to develop a method of biological control rather than chemical. The sterilization of male sea lamprey became a common practice in 1971 and was found to be extremely effective in controlling "spawning behaviour and [reducing] production of larvae in streams to a predictable rate."¹⁹ Pesticide use, targeted sterilization and manual trapping were common methods of sea lamprey control. However manual trapping was considered the least efficient in reducing the population due to the small percentage of the population able to be trapped at once. Traps and barriers "can capture up to 40% of the adult population" of the sea lamprey, which unfortunately is not high enough to notice a decline in reproduction. ²⁰ Lampricides and sterilization remain the most evidently effective tactics in sea lamprey control.

The development of the Welland Canal, initiated in 1829 and completed in 1932 played a pivotal role in exposing sea lamprey populations to the Great Lakes. The Canal's large route, which connected Lake Ontario and Lake Erie, ultimately created an efficient pathway for both the vessels and the creatures beneath them to gradually contaminate each of the Great Lakes over time. Both in the past and in present day, varying methods of management were implemented to maintain sea lamprey populations at a manageable and predictable number. This effort is crucial for preserving fisheries and deepening our understanding of how human-made structures, like canals, perpetually impact the environment and species around them. Through the study of these impacts, we can continue to develop sustainable practices to mitigate the ecological consequences of constructing large-scale infrastructure projects within the natural world.