Great Lakes Fish Displays Little Bladder Control Under Pressure!

Ann Arbor, MI — A small whitefish commonly known as the "bloater" lurks in the Great Lakes. Never heard of it? Probably because these fish live deep in the water column and so they are inaccessible to sportsfishing. Why are they called "bloater"? Because of the tendency to bloat when brought to the surface. The reason? Lower pressure. The "Why" and "How" are just now beginning to be understood.

Surprisingly little is known about a whitefish called the "bloater", despite the fact that these animals are one of the most abundant native fishes in the Great Lakes. Bloater are often caught by commercial fishermen and sold as "smoked chubs."

Recent findings have led scientists to acknowledge that the gas bladder-a balloon-like organ-may confine bloater to deeper depths. Or is this balloon-like bladder an adaptation to depth itself? Researchers Ben Clemens and Don Stevens have found intriguing information about the "mechanics" of the gas bladders of bloaters, providing some insight as to why these animals reside at deep depths and how they do it.

"Bloater are amazing animals, yet surprisingly few people know about them. They are a key link between the bottom and top of the food web. From a physiological view, we're just beginning to understand why they thrive at depth. Now the next step is understanding how," says Ben Clemens, a Michigan native and Doctoral student at Oregon State University. As Ben points out, "If we can understand why and how they thrive at depth, we'll be further along on understanding how to manage the Great Lakes food webs for sustainability."

The recent findings suggest that bloater have a similar anatomical design with a shallow water ancestor, yet they are unable to adjust for extensive changes in depth. Therefore, bloater thrive deep in the water column. "If society ever deems it necessary to raise bloater in hatcheries for stocking, how do you get these animals to their appropriate depth and have them live?" Ben queries. That's a deep issue.

Original Publication Information

Results of this study, "Comparative Gas Bladder Anatomy of a Deepwater Cisco and a Shallowwater Cisco: Implications for Buoyancy at Depth," are reported by Benjamin J. Clemens and E. Don Stevens in the latest issue (Volume 33, No. 2, pp. 505-511) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.

Contacts

For more information about the study, contact Ben Clemens, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, USA; Ben.Clemens@oregonstate.edu, (541) 929-7822.

For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.

Links

Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.