American Brook Lamprey
Upper body is olive-green to brown above, fading to light below, dorsal fin is completely divided into two distinct fins, teeth are weak and in clusters. A length of 5-8 inches is attained at adulthood.
Historically thought to be limited smaller streams in the northeast quarter of Iowa, it has more recently been recorded throughout the Upper Iowa, Upper Wapsipincon and Turkey River drainages, with a few scattered populations being found in the upper portion of the Iowa River drainage.
Larval stage feeds on minute plants, animals and bits of organic matter.
State Records are not documented for non-game species.
The secretive nature of the American Brook Llamprey's habits makes knowledge of its distribution rather vague and undetermined. Historically, it was thought to be limited smaller streams in the northeast quarter of Iowa. It has more recently been recorded throughout the Upper Iowa, Upper Wapsipincon and Turkey River drainages, with a few scattered populations being found in the upper portion of the Iowa River drainage. It is most often sampled during its spawning season in April.
The color of the American Brook Lamprey is olive-green to brown above, fading to light below. The dorsal fin is completely divided into two distinct fins. The mouth is a sucking disc, but is scarcely wider than the body. Teeth are weak, and are not formed in circular rows, but rather in several groups or clusters. There are from 65 to 70 myomeres between the last gill slit and the anus. A length of about 5 to 8 inches is attained at adulthood.
Spawning occurs in the spring, in small depressions in the sand, usually in swift current. The larvae live in burrows for several years and the adults live from the autumn of metamorphosis to the following spring, dying upon completion of spawning.
The food habits of the American Brook Lamprey are indeed very interesting. In its larval stage it feeds largely upon minute plants, animals and bits of organic matter. After the animal reaches maturity in the fall, the digestive system becomes non-functional, indicating that little food is consumed from fall until the next spring.
American Brook Lampreys have requirements basic to other brook lampreys and are associated with permanent streams ranging in size from large creeks to medium-sized rivers. It is sensitive to various types of pollution, including turbidity and avoids headwater creeks and large, silty rivers. In Missouri, the American Brook Lamprey is found in clear water with slow to moderate current. In Ohio the largest populations are found spawning in gravel riffles of upland creeks, at least 15 ft. average width, with high gradient. The American Brook Lamprey is commonly found only in small, upland creeks and rivers of east Tennessee and confined to small, clear streams in southeastern Minnesota.
Like the other lampreys in Iowa, these fish have no importance to anglers. It is on the threatened species list in Iowa (571 IAC 77.2(2) (2004)).
Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.
Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.
Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames.
Photo credit: Photo courtesy of Konrad P. Schmidt, copyright Konrad P. Schmidt.