Biology of the North American Anadromous Sea Lamprey, Petromyzon marinus

Abstract

The sea lamprey (Petromyzon marinus) in the western Atlantic Ocean adjacent to North America is usually found within a depth of 200 m between latitudes of 30 and 53°. Spawning size lampreys have been recorded in 116 rivers between 32 and 48° latitude. The upstream spawning migration which may extend to several hundred kilometres, takes place between March and September, the actual time varying directly with latitude. Fecundity of the anadromous P. marinus (approximately 124 000–305 000) is the highest for any lamprey species. Energy requirements for migration and reproduction are discussed in the context of parental investment. The larval phase lasts 6–8 yr and is followed by a highly synchronous period of metamorphosis. On completion of metamorphosis in late autumn some juveniles migrate downstream to the estuary or ocean and commence feeding. In at least some rivers, a portion of the young juveniles overwinter in the natal stream without feeding. Subsequent to a short feeding period in May these young juveniles leave the river for the sea. Sea lampreys attack a variety of marine elasmobranchs and teleosts. Only swordfish, Xiphias gladius, and striped bass, Roccus saxatilis, are reported to eat lampreys. During the marine interval, which lasts from 23 to 28 mo, the calculated instantaneous growth rate is 0.645–0.785 g∙d−1. Lamprey scarring frequency on Atlantic salmon, Salmo salar, in the St. John River, New Brunswick, increased from 2.6 to 15.0% between 1972 and 1975 coincident with a dramatic rise in the number of migrant salmonids. Scars were most prevalent on larger salmon, particularly females. Most scars were recorded on the right side of salmon, particularly in the ventral regions.Key words: sea lamprey, Atlantic Ocean, distribution, life cycle, growth, energetics, fecundity