Government and university biologists are mounting another, perhaps last search for the elusive Maryland darter, one of the world's rarest fish, which hasn't been seen in 21 years.

As reported in The Baltimore Sun today, scientists plan to check again the few Harford County streams where the little fish has only sporadically been found over the past century. But they also intend to broaden their search and bring in some new "electro-trawling" gear to see if the darter could be lurking in the Susquehanna River. A West Virginia biologist who's joining the search has had success finding other seemingly lost fish using the technique.

Rich Raesly, the Frostburg State University biologist who was the last to see the bottom-feeding member of the perch family in the wild, has searched in vain since then. He says the coordinated and expanded search, which scientists hope to make for two years, offers a "glimmer of hope" for the state's namesake fish.

If scientists still can't find it after that, the federal government will be left with a tough call - whether to declare it extinct and remove it from protection under the Endangered Species Act. No one likes to do that, if only because long-lost fish sometimes turn up. In the mid-1990s, Raesly and another scientist independently spotted another missing fish, the stripeback darter, after it hadn't been seen in 51 years.

For more on the Maryland darter, and the state's rare plants and animals, go here.

(Illustration by David Neely, courtesy of the MD Department of Natural Resources)