LAMPREY FAMILY (Petromyzonidae) 

 SEA LAMPREY 



Petromyzon marimis Linnaeus 



The sea lamprey is eel-like in appearance with a soft cartilaginous 

 skeleton, and represents a primitive group of fishes. Distinctive char- 

 acters are the round jawless mouth and the row of seven gill openings 

 along each side just behind the head. General range is the Atlantic 

 coasts of Europe and North America from Labrador south to Florida 

 in the Western Atlantic. In recent years sea lampreys have become land- 

 locked in the Great Lakes basin where they have almost eliminated some 

 commercial and sport fisheries. Fortunately distribution in Maine is 

 confined to coastal rivers and their tributaries. 



Sea lampreys spend their adult life in marine waters returning to 

 freshwater rivers to spawn during May and early June. As spawning 

 time approaches the digestive tract degenerates and the entire activity 

 and metabolism of the animal is concentrated on reproduction. Peak 

 of the spawning runs occurs at night although stragglers can be observed 

 moving upstream at all times. These migrating lampreys are seeking 

 a suitable area in which to build their nests. Usually nests are con- 

 structed in a rapidly moving current with a good volume of water and 

 with a gravelly bottom. Nests are rarely constructed in water over 

 two feet deep. 



Males make their way up the streams into freshwater spawning 

 areas first and do most of the nest construction carrying stones in their 

 sucking mouths. After the female arrives on the spawning area she may 

 or may not help with the nest. Nest completed, the male grasps the 

 female behind the head and wrapping his body around hers shakes 

 vigorously. Nonadhesive eggs are released, fertilized, and deposited at 

 the bottom of the nest in the gravel. A single female may have as many 

 as 235,000 eggs. Spawning completed, the adults drift downstream to 

 die. 



Several days later larval lampreys, called ammocoetes in this stage, 

 emerge from the nest and drift downstream seeking an area where the 

 gradient has leveled off" and flow is slight. Here they burrow into a mud 

 bank. These nonparasitic larvae feed for three to five years on organic 

 material strained from the water. At the end of the larval period, at a 

 length of four to six inches, they transform into the adult stage. The 

 transformation takes about two months and during this period the larval 

 lamprey loses the fringe of cirri, the eyes come to the surface, and the 

 horny teeth on the rasping tongue are developed along with anti- 

 coagulent secreting glands. 



Along the coast of Maine these newly transformed lampreys begin 

 their migration to the sea in the fall before the streams are ice covered. 



