A Dentist's Nightmare

Ships moving through Welland Canal.

Another attractive fish species, the sea lamprey (Petromyzon marinus), invaded the Great Lakes in the 1830s after a man-made canal system granted easy access to the basin. They moved from Lake Ontario to the rest of the Great Lakes after the completion of the Welland Canal in 1919.

The sea lamprey is  primitive fish with a cylindrical body and cartilage instead of bones. They do not have scales or a lateral line, paired fins or swim bladder. They are a parasite, which attach themselves to fish with their suction cup mouths and use their many teeth and rasping tongue to feed on fish blood and bodily fluids.

Sea Lamprey - enough to give anyone the heeby jeebies.

The sea lamprey was a large contributing factor to the collapse of the Great Lakes fishery. A single lamprey can kill upwards of 40 pounds of fish during their adult life stage. Only 20% of fish will survive an attack from a sea lamprey, but those that survived must cope with the resulting wound, which increases susceptibility of disease an infection. Canada and the United States harvested approximately 15 million pounds of lake trout from Lakes Huron and Superior per year. With sea lamprey numbers at their peak in the early 1960s, the catch was only about 300 000 pounds per year.

The Great Lakes Fishery Commission has collaborated with both Fisheries and Oceans Canada and the U.S. Fish and Wildlife Service to control and decrease populations of sea lamprey and to reduce the impact of this species on native fish populations. Several initiative and programs have been implemented including:

 1) application of chemicals such as TFM to sea lamprey spawning streams (selectively kills lamprey larvae)
2) construction of barriers allowing native fish to pass but prevent migration of sea lamprey
3) release of sterile males to compete with fertile males, which decreases reproductive success

New research in the use of sea lamprey sex pheromones may replace the use of chemicals (such as TFM) for controlling/removing spawning sea lamprey individuals. Sea lamprey populations have decreased by 90% from their peak in the 1960s. Need some type of conclusion in here.

Reference for most of the material reviewed in this blog. <http://www.invadingspecies.com/Invaders.cfm?A=Page&PID=3>