MOUNTAIN LIFE - Blue Mountains | Fall 2017

54 ML BLUE FALL 2017 link between the Mississippi and Great Lakes basins, making it a focal point in the battle to prevent aquatic invasive species moving between the two. Even if Asian carp can be kept from the Great Lakes, their continued spread throughout the Mississippi basin will see them reach 31 states and 40 per cent of the continental United States—a bona fide freshwater disaster. “The turning point for the public was the bi-national Asian carp meeting in Peoria, Illinois, in 2006,” Mandrak recalled. “It got good coverage, and media on boats filmed silver carp jumping out of the water. It was an Internet sensation.” Especially for Canadians, who’d never seen—let alone imagined—such a thing. We were worried, and so was our government. Enough to fund Asian carp prevention under the Department of Fisheries and Oceans (DFO) as far back as 2004. As current head of this Asian Carp Program (ACP), Becky Cudmore oversees what just might prove to be the best investment DFO has ever made. Shortly after my discussion with Mandrak, I visited Cudmore at the specially constructed Asian Carp Lab in the Canada Centre for Inland Waters in Burlington, Ontario. Chrome surfaces glinted under fluorescent light in a room lined with freezers and a DNA-handling area sealed by a pressure-lock door. Beside a large wall map depicting monitoring sites around the Great Lakes hung a 37kg bighead carp from the Illinois River, a fish of squat enormity, its sinister eyes riding low on the head. Across the room schooled a further rogue’s gallery: replicas of giant grass and black carp, and high-flying silver carp. “Canada and the U.S. jointly spend $30 million annually just to keep sea lamprey at a livable level,” she tells me, “and the Americans are spending $75 million a year to manage Asian carp. But we’re still working to prevent introduction , which is far cheaper. It only costs the ACP $3.5 million a year to prevent the introduction of these four species.” Monitoring began in 2013 with crews based out of Burlington and Sault Ste. Marie. Finding no Asian carps would have been the best outcome, but instead, three grass carp between 14–20kg turned up on Lake Erie’s north shore, one angled, the other two captured by net. Each proved to be “triploid”—a lab-induced form with three sets of chromosomes that thankfully cannot reproduce. Then four more grass carp were found in fall 2014 near Sandusky, Ohio, on Erie’s south shore. What did this mean? Unfortunately, there are pathways beyond CAWS through which Asian carps might enter the lakes. These include the aquarium, bait and live food trades—the reason it’s illegal to possess or sell live Asian carps in most provinces. During 2011 and 2012, vigilant Ontario Ministry of Natural Resources patrols spent 4,000 hours inspecting import and transport companies, stopping six live-fish haulers carrying over 13,000kg of Asian carps, netting several convictions and $100,000 in fines. But the threat continues. In late July 2015, a pair of grass carp were found at Toronto’s Tommy Thompson Park, a landfill spit on the city’s eastern waterfront. After an embayment being converted to a wetland was blocked off from the lake, a salvage was initiated to remove fish. The onsite biologist was immediately suspicious of two unfamiliar leviathans found during this process. The ACP was alerted. Blood samples showed the two male carps to be normal diploids (two sets of chormosomes), and Mandrak was asked to assess their reproductive status. “Each had well-developed testis in breeding condition and my guess is they were looking for a place to spawn,” he said. “Fortunately, there was no female around.” Also fortunately, stable isotope analysis showed the fish to be 11–15 years old and, as opposed to wild, likely hatched at U.S. fish farms. The ACP’s response was an excellent demonstration of prophylactic effectiveness on the part of both informed workers in the field and Cudmore’s team. If an Asian carp species was to establish in one of the Great Lakes, however, what was the prognosis? “The main population front of bighead and silver carp in the U.S. hasn’t moved since 2007, so frontline work there is buying time,” she told me. “Although it takes lots of manpower, our best tool is still monitoring. Any amount of proactivity is better than waiting—and far cheaper.” Cudmore was repeating the invasion biologist’s mantra: An ounce of invasive species prevention is worth a pound of perpetual management . Since then, several more grass carp have been found in scattered locations around Lake Ontario. At least one was a diploid female capable of reproduction—a first real warning that the highly invaded waters of the Great Lakes might soon suffer their greatest indignity yet. Leslie Anthony’s latest book, The Aliens Among Us: How Invasive Species are Transforming the Planet—and Ourselves , is published by Yale University Press. Available yalebooks.yale.edu and amazon.ca The invasion biologist’s mantra: An ounce of invasive species prevention is worth a pound of perpetual management .