Becker, George C. / Fishes of Wisconsin
Lamprey family - petromyzontidae, pp. 199-218 PDF (10.2 MB)
Sea Lamprey 213 The downstream drift of ammocoetes has been noted by Manion and McLain (1971). Most move- ment is in April and May at night, and during pe- riods of activity an increase in water level commonly increases the extent of downstream drift. This drift may account for the presence of ammocoetes which are now being found in the estuaries and bays of the Great Lakes. Transformation of ammocoetes into adults (100-180 mm long) begins in mid-July, and by October most are fully transformed (Manion and Stauffer 1970). Movement of recently metamorphosed sea lampreys begins in September and extends through May of the following year. Major movement occurs in October and November, with a lesser peak in April (Manion, pers. comm.). The new adults drift downstream and into the deep water of the Great Lakes, where they attach and feed on the blood and tissues of lake trout, large chubs, burbot, and other deepwater species. As the lampreys grow larger, they move shoreward, and in the fall they are found in relatively shallow water, where they now attack the lake whitefish, lake her- ring, walleye, yellow perch, round whitefish, sucker, and carp. As a sea lamprey feeds, an anticoagulant secreted by its buccal glands keeps the blood of the host fish from clotting, resulting in a free flow of food to the parasite (Schneberger 1947). Toward the end of the winter, the sea lampreys now 300-600 mm (12-24 in) long, begin to mature sexually and gather with others off the mouths of streams. Beginning as early as January, prespawning adults cease feeding or feed at a greatly reduced rate (Anderson and Manion 1977). While the sex glands are developing rapidly, the digestive tract is degen- erating, and further metabolism is dependent on the degeneration of the lamprey's muscles, skin, and even eyes. The adult phase lasts 12-20 months. The capture of tagged adults at least 2 months after the end of the normal spawning season, however, has indicated an extension of the parasitic phase of the life cycle beyond the usual 12-20-month period, pos- sibly due to late-season maturation of the gonads, disease, or deleterious effects of tags (Moore et al. 1974). The maximum length attained by the landlocked form of the Great Lakes sea lamprey is 76 cm (30 in) (MacKay and MacGillivray 1949). The saltwater (anadromous) form grows to 91.5 cm (36 in) and weighs 1.36 kg (3 Ib) (De Sylva 1964). Stauffer and Hansen (1958) reported that sea lam- prey larvae in Michigan streams of the Lake Superior drainage were most numerous in streams with sum- mer water temperatures of 10 to 26.1°C (50 to 79°F) and rarely occurred in cool spring-fed streams where brook trout and slimy sculpins were abundant. The movement of adult sea lampreys is extensive. Recapture of tagged sea lampreys (Moore et al. 1974) has shown that many individuals have traveled long distances and that movement between lakes is com- mon. Twenty-four lampreys tagged in Lake Huron were recaptured at widely scattered localities in northern Lake Michigan, and one was taken off Mil- waukee, 426 km (264 mi) from the tagging site. The distance traveled by sea lampreys tagged in northern Lake Michigan was as great as 298 km (185 mi) to the south (off Manitowoc, Wisconsin) and 450 km (279 mi) to the southeast (Grand Bend, Ontario). But about half (268, or 56%) of the 477 sea lampreys re- captured had moved no more than 15 km from the point of release. The fastest movement recorded was 11.1 km (6.9 mi) per day. Fish to which the sea lampreys are attached are probably responsible for some of their movement. Also, the sea lamprey has been known to fasten on to ships (B. R. Smith et al. 1974); divers who exam- ined 125 ships passing through the Canadian locks at Sault Ste Marie found 18 sea lampreys attached to the hulls. The sea lamprey's habit of hitching onto ships has no doubt greatly increased the rate of infestation of Lakes Michigan and Superior. In the laboratory, adult lampreys are more active during the daylight hours (Parker and Lennon 1956). Nonfeeding attachments on prey fish were observed to be common. A sea lamprey often attaches itself to a host for a considerable period of time and then shifts to one or more sites on the same fish before rasping a feeding hole. On the average, each sea lam- prey made 87 attacks and spent 2,383 hours of feed- ing and 523 hours of nonfeeding attachment, and was responsible for 8.39 kilos (18.5 lb) of fish killed. Female lampreys made more attacks, fed more, killed more fish, and grew larger than males. The research- ers estimate that the average fishkill by a wild sea lamprey exceeds and could be approximately double the number of fish killed by lampreys in the labora- tory aquariums. IMPORTANCE AND MANAGEMENT The sea lamprey is a known host to glochidia of the mollusk Anodontoides ferrussacianus (Hart and Fuller 1974). Sea lampreys are preyed on by several species of gulls, by herons, hawks, owls, bittems, water snakes, raccoons, muskrats, mink, weasel, fox, and by north- ern pike, walleye, and brown trout (Scott and Cross- man 1973). Minnows of genus Notropis and Rhin-
http://rightsstatements.org/vocab/InC/1.0/| Copyright 1983. The entirety of this book is available for viewing by the public as an Open Access text through the cooperative efforts of George Becker, the University of Wisconsin Press, and the UWDCC. This Work is copyrighted to the Board of Regents of the University of Wisconsin System. Any use of this material falling outside the purview of "Fair Use" requires the permission of the University of Wisconsin Press.