nd made available through the courtesy of Harman F. 
mith, indicated that the water quality was unusually 
igh and pollution was minimal. Average chemical 
alues were: total phosphates 1.2 ppm, nitrates 25 
pm, sulfates 69.7 ppm, and ammonium compounds 
| ppm. The alkalinity averaged 199 ppm, hardness 
85 ppm, and total dissolved minerals 376 ppm. Tur- 
idity varied during this period from 2 ppm to 138 ppm. 
In the vicinity of the study area the stream could 
e classed as a small to medium-sized river. During 
w water stages the channel was only 15 to 30 feet 
ide and in riffle areas barely a foot in depth, although 
lere were some deep pools at bridge sites and at 
brupt bends in the river. During flood stages the 
oodplain was inundated, and the river was almost 1 
ile wide. 
The study area consisted of a 5-mile stretch of the 
ver (the encircled area in Fig. 1) and several nearby 
cations, which were sampled when the main stations 
ere inaccessible because of high water. One of the 
rincipal sites (Fig. 2, top), one mile west of Greenup, 
id a variety of habitats — gravel bars and gravelly 
iceways, sand bars and sandy raceways, a rubble riffle, 
id several silt-bottomed pools. Another site (Fig. 2, 
ttom), 3 miles southwest of Greenup, was similar but 
id more extensive stretches of sand bottom and lacked 
ibble and strong riffle areas. 
METHODS 
A total of 37 collecting trips was made to the study 
ea between August 4, 1967, and July 1, 1969. Ini- 
uly various habitats were sampled to determine habitat 
eferences; later efforts were concentrated in the 
annels, where the darters were usually abundant and 
ore easily obtained. Collections were made by min- 
Ww seine at approximately 2-week intervals from 
ugust to November in 1967 and at irregular intervals 
roughout 1968 and early 1969 in an effort to obtain 
much information as possible for all seasons. Con- 
lerable difficulty was encountered in obtaining speci- 
ens during several periods of high water, but 
entually specimens were secured for every month 
cept January. Specimens collected during the 2-year 
idy period were distributed as follows: February, 12; 
arch, 8; April, 6; May, 27; June, 26; July, 20; August, 
3; September, 60; October, 53; November, 38; and 
scember, 2, for a total of 300 specimens. 
Supplemental collections from previous years in the 
me area provided additional specimens and _ helped 
| gaps resulting from flood periods. A total of 526 
eserved specimens were examined during the study for 
formation on food and reproduction within the study 
ca, but the information on growth and other facets 
the life history were based on the 300 specimens 
eured during the study period. 
Specimens from the study area were measured, their 
€ and sex were determined, and details of color 
(tern and the presence of external parasites were 
3) 
noted. Young darters were examined for developmental 
features and for growth. Most of the adults were 
dissected and gonad conditions were noted. As spawn- 
ing time approached, the dimensions of gonads were 
recorded and ovarian egg counts were made on several 
females. Age determinations were made by counting 
the number of annuli on scales removed from the 
dorsum on the left side of the body near the junction 
of the spinous and soft dorsal fins. 
The stomachs of most of the adults and 20 percent 
of the young were examined for food organisms. 
Stomachs of some potential predators of P. sciera were 
also examined for darter remains. 
During the spring, water and air temperatures were 
routinely taken, and notes were made on the river and 
weather conditions, coloration of the fish, and habitats 
in which specimens were captured. Care was taken not 
to deplete the darter population, and no more than 35 
specimens were taken, even when the Species was 
abundant and easily captured. Specimens were dropped 
into approximately 10-percent formalin as soon as they 
were captured. 
Living specimens were brought to the laboratory 
from time to time so that their behavior could be 
observed in aquaria. When it became evident that 
Captives were not going to spawn in the laboratory, 
eggs and sperm were stripped from ripe adults into 
petri dishes and kept until the eggs hatched. 
On October 17, 1967, a quantitative sample was 
taken one-half mile north of Greenup with an electric 
seine to estimate the composition of the total fish fauna 
at the site, the numerical relationships of the component 
species, and the number of individuals per Square yard 
of habitat. A 150-foot stretch of the river was blocked 
off by minnow seines held in place by steel rods, so 
that fishes could neither enter nor leave the enclosed 
area, and the number of square yards was calculated. 
A 30-foot electric seine with 15-inch drop cords at 
30-inch intervals was moved from the downstream to 
the upstream block repeatedly in an attempt to kill 
all fishes in the enclosure. Dead fishes were picked up 
by hand and with dipnets in clear water; those in deep 
or turbid pools where they could not be seen were 
removed by repeated seining of these pools. 
HABITAT AND ASSOCIATED SPECIES 
In the study area all sizes of P. sciera were most 
often found in that portion of the river channel that 
had a combination of gravel bottom, rapid or fairly 
rapid current, and a depth of at least 1 foot. The 
species was seldom found over bottom materials 
other than gravel and never found in quiet pools or 
Shallow water. Accumulations of branches and leaves 
in the gravel of the channel often contained darters, 
suggesting that these were hiding or resting sites. Cap- 
tive darters hid under large rocks or other objects on 
the bottom of the aquarium. 
In Ohio a preference on the part of dusky darters 
