Experts are keeping an eye on the St. Clair River, as sea lamprey numbers are on the rise in Lake Erie.
The Great Lakes Fishery Commission reported earlier this month that populations of the invasive sea lamprey remain at near-historic lows in Lakes Michigan, Huron, and Ontario, though the destructive, parasitic pest has increased in abundance in Lakes Superior and Erie.
Sea lamprey population increases in Lakes Superior and Erie were greater compared to the other lakes even as abundances are generally holding steady.
The Commission and its partners believe sea lamprey populations across the basin may be rebounding from the harsh winters of 2013/2014 and 2014/2015, though other factors such as prey availability and warmer water temperature may be factors as well.
In response to the increased numbers, the Commission and its partners have ratcheted up control in problem areas and heightened monitoring and assessment so that future control efforts will be targeted effectively.
Sea lampreys remain a constant battle in the Great Lakes, as the invader, native to the Atlantic Ocean, reproduces in the lakes and destroys many species of fish.
Today, the Great Lakes fishery is worth $7 billion annually to the people of Canada and the United States.
Without sea lamprey control, the fishery would suffer significant ecological and economic harm.
Before control, sea lampreys killed an estimated 103 million pounds (47 million kilograms) of fish per year.
Today, because of control, sea lampreys kill less than 10 million pounds (4.5 million kilograms) of fish per year.
Great Lakes Fishery Commission officials say the sea lamprey is one of the worst human-caused ecological disasters ever inflicted upon the Great Lakes.
Sea lampreys invaded through shipping canals and, by 1939, were present throughout the system.
They attach to Great Lakes fish with a tooth-filled, suction cup mouth and file a hole through the fish’s scales and skin with a razorsharp tongue.
The average sea lamprey will kill up to 40 pounds (18 kg) of fish during its parasitic stage.
Sea lampreys prefer trout, salmon, whitefish, and sturgeon, but they also attack smaller fish like walleye and perch.
Given the tremendous damage sea lampreys caused, Canada and the United States, through the 1954 Convention on Great Lakes Fisheries, charged the Great Lakes Fishery Commission with implementing sea lamprey control and research; the commission partners with Fisheries and Oceans Canada, the US Fish and Wildlife Service, and the US Geological Survey to deliver the program.
Sea lamprey control consists of several techniques including lampricides, barriers, and traps.
The commission also is experimenting with chemosensory cues as a way to disrupt spawning behavior. For more information, visit www.glfc.org/sea-lamprey.php.
“Sea lampreys are the scourge of the Great Lakes and must be controlled,” stated David Ullrich, chair of the Great Lakes Fishery Commission, in a press release.
“Without sea lamprey control, the Great Lakes fishery would be laid to waste by the voracious predator. Unfortunately, sea lampreys are here to stay. Fortunately, we can control them. Sea lamprey abundances are reported as 3-year averages. For more information about methodology and to see lake specific graphs, visit www.glfc.org/status.php effectively such that we lose only a small amount of fish to lamprey compared to the hundred million pounds lost each year prior to our control program. Sea lamprey control is worth the effort and is the foundation of the fishery we enjoy today.”
Ullrich added: “Today’s news about sea lamprey abundances provides reason for optimism but also is a caution against complacency. Although we saw increases in Lakes Superior and Erie, we still are at or near historic lows in sea lamprey abundances in the remaining Great Lakes. The success of the program is due to extraordinary work carried out by our control partners. Sea lampreys are resilient beasts and we cannot let up on our control effort. We will always work aggressively to reach our sea lamprey suppression targets in all lakes.”
Robert Hecky, the Commission’s vice-chairman, says overall, the sea lamprey control program has been a tremendous success.
“The control program provides fish a chance to survive long enough to spawn, be caught by humans, or live a natural life,” he said in a press release.
“It also allows agencies to restore stressed species and maintain thriving sport, commercial, and tribal fisheries.”
By lake, the latest sea lamprey status is as follows:
Lake Erie: The reasons for the relatively high abundances in Lake Erie are not apparent. Sources to watch include the St. Clair River, the only known source of sea lamprey not treated regularly. Intensive larval survey efforts recently conducted to identify previously undetected populations did not reveal any untreated tributaries. Preliminary acoustic telemetry results indicate that adult sea lamprey are exploring tributaries not currently treated, however, that does not necessarily mean the tributaries are producing sea lamprey. Larval assessment surveys will be conducted to look for recruitment in these tributaries
Lake Ontario: Consistent treatment effort on Lake Ontario for the past 25 years has contributed to keeping lamprey numbers at or near target and historic lows. Sources to watch include the Niagara River, but this connecting channel currently has a low larval sea lamprey abundance.
Lake Michigan: Heightened and targeted treatment strategies in Lake Michigan employed since 2012, and biennial treatment of the Manistique River since 2003, have contributed to historic lows in abundances; targeted treatment was applied again in 2017. Lake Michigan likely benefits from treatments in the northern portion of Lake Huron (e.g. St. Marys River). Sources of concern include tributaries that are difficult to treat in the northern and eastern portions of the lake.
Lake Huron: Heightened and targeted treatment strategies in Lake Huron employed since 2010, including two large-scale treatments of the St. Marys River, have contributed to historic lows in lamprey abundances; another round of targeted treatment is scheduled for 2018. Lake Huron likely benefits from the treatment of tributaries in the northern portion of Lake Michigan (e.g. Manistique River). Sources to watch include the St. Marys River and tributaries that are difficult to treat in the northern portions of the lake.
Lake Superior: A targeted treatment strategy was implemented in 2016, and the impact of these efforts will not be seen until 2018. The reasons for the relatively high abundances in Lake Superior are not fully apparent. Sources to watch include lentic areas of the Chippewa, Nipigon, Gravel, and Batchawana rivers. Treatments have recently occurred in these systems. The Bad River has also been treated recently, however, some concerns remain that treatment effectiveness may not have been ideal for this system. The St. Louis River, which has undergone significant restoration as an area of concern through the Great Lakes Water Quality Agreement, looms as a potential sea lamprey producer that would be difficult to treat.
