(c) Predation 



Since the beginning of the present investigation, occasional 

 observations -were made, or reports received, of predation upon 

 migratory or spaiming sea lampreys by fishes, birds, and mammals. 

 Perhaps the most interesting observations are those of predation 

 by fishes. On June 27, 19U7, a walleyed pike, 17.0 inches in 

 total len^h, taken on a lure in Ocqueoc Lake, was found to have 

 swalloived a mature, adult, female sea lamprey lU.^ inches long. 

 At the time oi capture, several inches of the sea lamprey's tail 

 were still protruding from the walleye's mouth. In the stomach, 

 digestion of the head region had barely begun. Conservation 

 Officer Charles Vanderstar of Naubinway, Michi^n, reported that 

 a 16-inch (sea) lamprey was removed from the stomach of a 7 1/2- 

 pound (northern) pike taken from jailecoquin Lake, Mackinac County, 

 on June 17, 19li3. This ivatershed is knoivn to support a moderately 

 large sea lamprey spawning run. Mr. B. L. Foresnan of Alger, 

 lachigan, reported finding a 13-inch sea lanprey in the stomach of 

 a k 3/U-pound brown trout. This trout was taken in the Rifle River, 

 Ogemaw County, during the month of l!Iay, 19U3. Lilce the Millecoquin, 

 the Rifle River has a sizable sea lamprey run. 



These records ivould indicate that mature sea lampreys, regard- 

 less of their size or habits, are not immune to attack by large, 

 predatory game fishes. Many more are undoubtedly destroyed by 

 such fishes than ever come to the attention of interested observers. 



The sea lamprey appears most vulnerable to attack by birds 

 and mammals ivhile on its spaivning bed. On Jxine 22, 19U7, the par- 

 tially devoured carcasses of several sea lampreys were found on 

 the bank adjacent to a crowded spawning riffle in the Little Ocqueoc 

 River, Presque Isle County. Tracks of a raccoon at the carcasses 

 and lamprey teeth found in nearby raccoon scats identified the 

 predator. Less conclusive evidence found several days later on 

 the Ocqueoc River indicated that a minlc may have captured and par- 

 tially devoured a sea lamprey. I have also noted several domestic 

 dogs which enjoyed capturing spa-wning sea lampreys and dragging 

 them out on the banicj they were seldom eaten by the dogs in the 

 presence of the observer. 



During late June, 19U8, a great blue heron was observed on 

 several occasions fishing in one of the scattered spaT.ming riffles 

 in the Ocqueoc River (T36N, R3E, S.33). Although this bird could 

 not be approached closely at any time, it was observed on one 

 occasion in the act of swallowing a spaivning sea lamprey. 



The peak of spawning activity in the Ocqueoc River in both 

 19U7 and I9I1.8 was accompanied by daily concentrations of gulls 

 (presumably herring, ring-billed, and Bonaparte's gulls) -vdiich flew 

 into the most heavily used spairvning areas each morning. They were 

 observed picking up both spawning, and spent and dead sea lampreys. 



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