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* Adults parasitic upon other fishes, attaching to host with suction-cup mouth. Sharp teeth cut through skin and scales and the blood is extracted.
* Remains attached to host over a long period of time unless brushed off by the distressed fish. Fishes almost colorless from the loss of blood have been observed with several lampreys attached, but they seldom kill the host since that would deprive them of their food source.
* Adults attack a variety of fish including trout, Whitefish (Coregonus clupeaformis), Smelt (Osmerus mordax), Pike (Esox lucius), White Sucker (Catostomus commersoni), Brown Bullhead (Ictalurus nebulosus), Rock Bass (Ambloplites rupestris), Walleye (Stizostedion vitreum), and even the armored Lake Sturgeon (Acipenser fulvescens).
* Ammocoetes (larval young) feed on drifting plankton and detritus.
History:
* The earliest known lampreys, Mayomyzon, are from the Pennsylvanian Period, about 300 million years ago. They are thought to be related to an extinct group of jawless fishes, the ostracoderms, which flourished earlier.
* Populations of native lamprey are generally in decline throughout their range.
Uses:
* Parasitic feeding habits limit their appeal to anglers.
* May have some value as forage for predatory game fish.
Reproduction:
* Spawns in May and June when the water temperature reaches 50º F. Adults ascend small tributary streams to spawn among rocks in sand and gravel bottom riffles.
* Nests are built in shallow gravelly riffles. The adults constantly work on the nests with short interruptions for spawning. The female attaches to a rock and the male attaches to her head, wrapping his tail around hers to bring the genital openings close together. The pair vibrates as the eggs and sperm are released; then they separate and return to nest building.
* The adults die when spawning is completed.
* Eggs are approximately 1mm in diameter; the average female produces 10,800 eggs. Larvae (known as ammocetes) resemble their parents except that they are blind and the mouth hooded, toothless, and provided with a fine-mesh tissue sieve.
* After hatching, the ammocoetes drift downstream to quiet waters where they live in small burrows in the bottom ooze for 4-7 years. At this stage they are not parasitic, feeding largely on algae and microscopic animals.
* Ammocetes metamorphose in the fall when they are about 3″ long. They remain in the streams over winter, then move downstream to rivers and lakes in search of hosts.
* After one, or possibly two, years as parasites, the adults return upstream to spawn and die.