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Becker, George C. / Fishes of Wisconsin

Lamprey family - petromyzontidae,   pp. 199-218 PDF (10.2 MB)

Page 213

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. 
 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. 
The sea lamprey is a known host to glochidia of the 
mollusk Anodontoides ferrussacianus (Hart and Fuller 
  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- 

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