Darby Creek Advocate Volume 9, Issue 3  November 2001

Big Darby Creek is known for its rare and endangered species. One of the rarest and most threatened is the spotted darter.
The 2-3 inch spotted darter is an attractive, stream-lined fish adapted to life in fast riffles. It gets its name from the red spots that grace the breeding male. As in many darter species, the female is rather plain.
Darters are undoubtedly Darby’s most famous creatures. Anyone who has gone “creeking” in the stream will have been introduced to these colorful little fishes. In addition to their beauty, darters are excellent indicators of water quality because most species live on the stream bottom and require a clean, healthy substrate.
At approximately 150 species, darters represent one of the most diverse families of freshwater fishes in the world. Darters are restricted to North America, with the great majority concentrated in the eastern Mississippi drainage.
With 16 native species Darby ranks as one of the most diverse darter streams for its size. In fact, Milton Trautman, Ohio’s most famous ichthyologist, once claimed that Darby held the record for most darter species caught in one riffle in one day (13).
On a global scale, the spotted is Darby’s rarest darter. It is limited to isolated populations scattered throughout the Ohio River Basin, and for this reason has been monitored by the federal government for possible inclusion as an endangered species.
In Ohio the spotted darter is considered endangered, with the last population of any size is in Big Darby Creek. Elsewhere, recent sightings have been limited to a single riffle in the Kokosing River, and a lone individual found in the Olentangy River at Highbanks Metro Park. (There is one other record, which I will discuss shortly.)
Within Darby, the spotted darter has had a mysterious history. For unknown reasons, Trautman did not encounter the fish during his first decade of study (1920-29), despite repeated surveys in the heart of its range, namely the lower Big Darby near the Scioto River. Thereafter the fish was found sporadically: 1 in 1930, 7 in 1943, 6 in 1947, 7 in 1948, and 1 in 1956.
Today the spotted darter is still found in this section of Darby, although it is usually not common and seems to fluctuate radically in abundance. This pattern suggests that though Big Darby supports Ohio’s largest population, the species is only marginally successful here.
The likely reason is a lack of habitat. Like many darter species, the spotted darter favors specialized living conditions, namely swift riffles where it hides, hunts, and breeds near large rocks. This habitat is typical of high gradient streams flowing through bedrock deposits, but is not common in Darby, which flows through flat glacial till with relatively mild riffles and smaller gravels. As a result, the spotted darter appears to be limited to places where sudden drop-offs combine with a few larger stones to produce isolated niches of appropriate habitat.
Despite this limitation, there is some evidence that spotted numbers may be increasing in Darby. A possible explanation is that alterations in stormwater runoff (see p. 7) have increased habitat. Greater stormwater flows tend to scour out the substrates in riffle areas, leaving behind the larger stones the spotted darter needs.
Several years ago I got a memorable lesson in the fluctuations of Darby’s spotted darter population. It was December of 1998, and my friend Dana Akison and I had traveled to Pickaway County to seine for fishes on a favorite riffle that usually offered a nice selection of fish—and occasionally produced the elusive spotted darter.
After one seining pass it appeared we had a problem: the mesh of our net was clogged with small pieces of algae, a major nuisance in sampling for fish. Then we took a closer look. What appeared to be algae was in fact hundreds of green caddisfly larvae, a common aquatic insect. Our riffle was crawling with thousands of them!
Such a hatch usually means a feast for fish, and sure enough as we looked about our feet we spotted the white bellies of stonerollers and gravel chubs flashing in the tumbling water as the fish nuzzled the substrate in pursuit of this insect bonanza. In a little over an hour we caught dozens of these minnows, plus darters, madtoms, and other fishes.
Most amazingly, the spotted darter—which usually makes up a tiny fraction of the fish present on this riffle—was suddenly the most common fish. We estimated our catch at 75.
What was going on here? Had Darby’s water quality miraculously improved? After giving the situation some thought, we concluded that we were seeing the effects of unusually favorable weather conditions. After huge floods earlier in the year, central Ohio had settled into a severe and prolonged
drought. As a result, Darby’s riffles had lain undisturbed by flood waters throughout the summer and fall. In these stable conditions the caddisfly hatch had apparently been tremendous, and the fish hatch had followed suit. It was probably no coincidence that all but one of the spotted darters we caught appeared to be that year’s hatch. As for why the spotted darter outnumbered other species—who can say?
In the years that followed, the spotted darter expanded its range dramatically in Darby, and was regularly found as far upstream as Battelle Metro Park. Whether it maintains this expansion may depend on the vagaries of future weather patterns.
A final note on the spotted darter and Big Darby Creek. As one of the last refugia for rare species, Darby offers a source of colonists should other streams in the region become less polluted. In the same year that we found the species gorging itself on the riches of the lower Darby, for the first time a spotted darter was captured in the Scioto River, just 3 miles below Darby’s mouth. Over the past decade other Darby fishes have been reappearing in the increasingly clean Scioto, and just this year the Ohio EPA upgraded a section of this once great river to “exceptional warm-water habitat,” the state’s highest rating.
Thus preserving Darby has paid dividends beyond the borders of the watershed. Hopefully, these dividends will be fruitful and multiply, and replenish the damaged streams of central Ohio with their rightful animal life.

by John Tetzloff

Sources: Milton B. Trautman, The Fishes of Ohio. Thanks also to Dennis Mishne of the Ohio EPA for supplying fish data.