Life history of freshwater shrimp, key in fishery recovery
Ann Arbor, MI — In Lake Pend Oreille, Idaho, a small non-native freshwater shrimp (Mysis diluviana, or mysids) is linked to the decline and recovery of kokanee salmon. Mysids compete with young kokanee for small zooplankton food. Kokanee are important to the ecosystem because they are an important prey resource for bull trout, a species listed as threatened by the federal government.
Researchers at the University of Idaho have begun to take the first steps to manage mysids in Lake Pend Oreille since their introduction in the 1960’s and 1970’s. "Understanding the growth and life history of the shrimp is important to possible management plans that may lead to the recovery of the fishery in Lake Pend Oreille", says Timothy Caldwell, masters student and researcher for the University of Idaho. "Once we understand reproductive patterns, and periods of time when they are growing and consuming prey rapidly we can time and maximize the effectiveness of management strategies such as mysid removal."
Mysids mate in the fall, and release their young in late spring. Coincidentally, this is just before the time period at which kokanee salmon fry are released into the environment. Because mysids are released before kokanee, and outnumber them greatly, mysids win the battle for food resources in spring. Additionally, adult mysids are growing at their highest rate during these periods of time, indicating they are consuming prey rapidly. Because of the release of young and the high rate of growth, mysids act as a double edged sword against kokanee salmon. These findings may be used to begin placing mysid management plans into action, in order to recover the fishery.
Original Publication Information
Results of this study, "The life history characteristics, growth and density of Mysis diluviana in Lake Pend Oreille, Idaho, USA," are reported by Timothy J. Caldwell and Dr. Frank M. Wilhelm in the special issue on Mysids of the Great Lakes, of the Journal of Great Lakes Research, published by Elsevier, 2011.
Contacts
For more information about the study, contact Timothy Caldwell, Dept of Fish and Wildlife College of Natural Resources, University of Idaho, Moscow, ID, 83843; cald3105@vandals.uidaho.edu, (717) 575-7843.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, Environment Canada, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; jglr@ec.gc.ca; (306) 975-5310.
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