BIO 203


      Silver Lamprey are only parasites during the adult part of life, which only lasts about one to two years (Docker et al. 2009).  But this is the form that lamprey are most commonly associated with.  Since Silver Lamprey are aquatic freshwater parasites they prey exclusively on fish.  Silver Lamprey prefer hosts without scales or scales that are very small in size.  For this reason their favorite hosts to attach are catfish, paddle fish, sturgeon, and lake trout (Cochran et al. 2003).  But, Silver Lamprey are opportunist and will attach to many different species of fish.  Studies have shown that when lamprey use invasive carp species with large thick scales as their host they experience very little growth (Cochran et al. 2003).  This is thought to be caused by lamprey being unable to successfully bore through the carps scales and create a viable hole to acquire blood and other nutrients through.

Mouths of different lamprey species

Shown above are the  mouth structures of different species of lamprey. 

    Silver lamprey have been found to attach more commonly to the backs of fish who feed on the bottom of rivers.  This lessens the chance of the lamprey being disattached from its host by being scraped off by debris on the bottom of rivers and bodies of water.  Lamprey are found on paddlefish and other fish who commonly inhabit the pelagic zone (Cochran et al. 2009).  The skin on the underbellies of paddlefish is softer and contains high amounts of oil.  For both of these reasons Silver Lamprey prefer to attach to the underbellies of paddlefish.  It is hypothesized that Silver Lamprey may actually be able to use the oil itself as a nutrient source (Cochran et al. 2009).
    In the winter some Silver Lamprey remained attached to their host while others live without host for extended amount of time and attach to rocks and other objects near the bottom.  The exact number of Silver Lamprey who remain attached to host for winter months is unknown, because of the many difficulties observing and tracking lamprey during the winter in their natural habitat.  It is thought that Silver Lamprey prefer a larger host in the winter.  Larger hosts allow for a greater amount of resources so the lamprey doesn’t have to waste precious energy searching for a new host.  It also gives the lamprey more protection (Cochran et al. 2009).
    The exact number of predators of Silver Lamprey is unknown.  Animals are rarely observed eating Silver Lamprey in the wild.  Silver Lampreys are also easily digested by many animals because they have very few bones.  The populations of Silver Lampreys are dispersed for most of the year too, making sightings of predation harder to come by (Cochran et al. 2009).  Walleye, brown trout, and northern pike are all known fish species who prey on Silver Lampreys.  Northern pikes have been observed feeding on Silver Lampreys as they make their yearly migrations. Nothern Pike, (Esox luciu), are known predators of Silver lamprey.  Picture courtesy of Wiki Commons. Walleyes have been known to feed on ammocetes who preside on muddy bottoms.  Birds who are predators of Silver Lampreys include gulls and mergansers.  Mergansers are one of the only species that is known that uses Silver Lamprey has a main staple of their diet.  Raccoons, muskrats, rats, weasels, foxes, hawks, and owls are all thought to be predators of Silver Lampreys, but have seldom, if at all, been seen actually consume a Silver Lamprey (Cochran et al. 2009).  Silver Lampreys aren’t known to be a fish that humans enjoy eating, but more as a parasite that destroys other fish we enjoy eating.  Silver Lampreys are used by different fishermen mainly in the ammocete stage as bait for some game fish.  Fly fishermen also also make flies that resemble Silver Lamprey ammocetes (Cochran et al. 2009).

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