Roy C. Heidinger

Mass-Marking Otoliths of Larval and Juvenile Walleyes by Immersion in Oxytetracycline, Calcein, or Calcein Blue

Abstract Immersion of larval and juvenile walleyes Stizostedion vitreum for 6 h in a 500-mg/L solution of oxytetracycline hydrochloride or Calcein resulted in fluorescent marks on 100% of the otoliths. Few marked fish (≤27.0%) were found after immersion in Calcein blue, Immersion of larvae at 15°C resulted in significantly higher mortality (57.7%) than at 10°C (20.9%). Mortality at 10°C was lowest for larvae immersed in oxytetracycline (9.0%) and greatest for those immersed in Calcein (41.6%). Juvenile mortality (1.3–32.7%) was correlated with high pond water temperatures during June (26.1°C) and August (32.2°C). All of the juveniles survived when immersed in any of the three chemicals in cases where pond water temperatures were less than 20°C at the time of collection.

Food Intake of the Largemouth Bass

Abstract During 18 months of electrofishing a sample of 991 adult largemouth bass (Micropterus salmoides) was taken from Crab Orchard Lake. The stomach contents were removed in the field with a gastroscope. Gizzard shad (Dorosoma cepedianum) constituted the principal forage fish. Approximately 50% of the bass collected had empty stomachs. As the size of bass increased, the food intake as a percent of body weight decreased. Ninety percent of the bass stomachs contained one food item. When more than one food item was found, they were usually in the same stage of digestion. It is suggested that the high percent of empty stomachs was related to hunting success, or that the onset of the feeding stimulus in association with rate of digestion might result in a periodicity of feeding that involves a high percent of empty stomachs. A higher relative intake of food by small bass was postulated to be a result of the basss typically consuming only one fish. Inasmuch as the forage fish were relatively uniform in size...

Habitat Use by Middle Mississippi River Pallid Sturgeon

Abstract Little is known about the habitat preferences and needs of pallid sturgeon Scaphirhynchus albus, which was federally listed as endangered in 1990. To learn more about habitat use and selection by pallid sturgeon, sonic transmitters were surgically implanted in 27 individuals from the middle Mississippi River. Study fish were located 184 times (1–23 times/individual) from November 1995 to December 1999. Of the seven macrohabitats identified, pallid sturgeon were found most often in main-channel habitats (39% of all relocations) and main-channel border habitats (26%); the between-wing-dam habitats were used less often (14%). Strausss linear selectivity index (Li ) values indicated that study fish exhibited positive selection for the main-channel border, downstream island tips, between-wing-dam, and wing-dam-tip habitats; they showed negative selection for main-channel, downstream of wing dams, and upstream of wing dam habitats. Comparison of Li values for four temperature ranges and three daily me...

Relative Survival of Three Sizes of Walleyes Stocked into Illinois Lakes

Abstract The ability to differentially batch-mark several size-groups of fish stocked concurrently in lakes or rivers makes it possible to compare survival within a single year. We evaluated stocking of walleyes Stizostedion vitreum in Illinois during 1991–1996. Ten lakes were stocked with combinations of two or three sizes of walleyes, including fry and small (50-mm) and large (100-mm) fingerlings. This permitted a total of 73 lake-year comparisons: fry versus large fingerlings (23 lake-years), fry versus small fingerlings (29 lake-years), and small versus large fingerlings (21 lake-years). Stocked fish were differentially marked with oxytetracycline or fin clips. Electrofishing catch per effort, relative survival, and population estimates were used in conjunction with production costs to compare size-based contributions and survival. Survival generally favored fingerlings over fry (70% of lake-years for small fingerlings, 67% for large fingerlings) and small fingerlings over large fingerlings (72% of la...

Relative Survival and Contribution of Saugers Stocked in the Peoria Pool of the Illinois River, 1990–1995

Abstract Numbers of sauger Stizostedion canadense declined in the Peoria Pool of the Illinois River from the 1970s to the 1990s. Stocking was evaluated as a means of supplementing natural reproduction in the pool. Marked fry were stocked in 1991–1994 (20–176/ha), and marked fingerlings were stocked in 1990–1995 (<1–20/ha). In 1990, fingerlings with a mean total length of 44 mm were stocked in June, and 92-mm fingerlings were stocked in September and October. Relative survival was 4.9:1 in favor of the 44-mm fingerlings. During 1991–1994, relative survival averaged 440:1 for stocked fingerlings (39–61 mm) versus fry. From 1990 to 1995, contribution of stocked saugers to the year-classes averaged 33.9% at age 0. Because of the immigration of wild saugers into Peoria Pool and emigration of stocked and wild fish to other pools, contributions of stocked saugers to individual year-classes decreased each year subsequent to stocking. Mean contribution of stocked saugers at harvestable ages (age 2 and older) was 9...

Comparison of Channel Catfish Age Estimates and Resulting Population Demographics Using Two Common Structures

Abstract Sagittal otoliths and the articulating process of the pectoral spine have both been validated as accurate techniques for estimating the age of channel catfish Ictalurus punctatus (≤age 4). However, there is limited information on the relative precision of estimates from these two structures. Thus, we analyzed the precision of age estimates derived from otoliths and the articulating process of the pectoral spine and compared the dynamic processes (recruitment, growth, and mortality) resulting from those estimates. Aging structures were removed from 110 channel catfish captured from the Wabash River (river kilometers 550–9.6) via day–time electrofishing. The age estimation methodologies were similar to those described in previous studies. Agreement between the ages derived from the two structures was high; the average percent error was 8.4%, the coefficient of variation was 11.4, and the slope of the age bias plots did not differ from 1, indicating similar age assignments between structures. The co...

Accuracy and precision of age determination techniques for Mississippi River bighead carp Hypophthalmichthys nobilis (RICHARDSON 1845) using pectoral spines and scales

Age determination techniques for bighead carp Hypophthalmichthys nobilis from the Mississippi River (MR) were investigated. Sagittal otoliths, cleithrum bones, scales, and pectoral spines were obtained from bighead carp collected from the middle Mississippi River (MMR) and from Pool 26 of the MR. Known-age bighead carp (Age 1, N = 3 and age 2, N = 5) pond-reared in a fish farm were used to aid in the interpretation and validation of age assessments. Sagittae and cleithra were cloudy and annuli were difficult to identify both in whole view and sectioned; they were not evaluated further. All pectoral spine sections (N = 98) and scales (N = 57) from known-age and unknown-age specimens were read by three readers. Readers were provided with the date of capture and were not informed of the presence of known-age bighead carp. Percent agreement among age estimates from unknown-age bighead carp was 19 % for scales and 23 % for spine sections. There was approximately 60 % agreement within one year for both structures. Agreement for age 1 bighead carp using scales was 100 %, and 20 % for age 2 specimens. Using spine sections, agreement was 67% for both age 1 and age 2 known-age bighead carp. Mean percent accuracy interpreting the age of known-age bighead carp was 69 % for spine sections and 78 % for scales. Accuracy of scale readings was 100 % for age 1 and 60% for age 2. A multiple regression analysis of age estimates by the readers showed no significant difference (p >0.05) between the aging structures and the dependent variable, estimated age, but a significant aging structure by mean estimated age interaction was found. Scales yielded lower age estimates than spine sections for older bighead carp, while spine sections yielded lower age estimates for younger bighead carp. We suggest using pectoral spine sections to age older bighead carp (2 and older), because they showed more and sharper annuli than scales.

Frequency of Natural Hybridization between Saugers and Walleyes in the Peoria Pool of the Illinois River, as Determined by Morphological and Electrophoretic Criteria

Abstract External morphological characteristics and protein electrophoresis at two diagnostic loci were used to determine the proportion of 704 Stizostedion samples collected from the Peoria Pool of the Illinois River during March 1995 that were saugers S. canadense, walleyes S. vitreum, or their hybrids. Morphological analyses indicated that 616 (87.5%) fish were saugers, 58 (8.2%) were walleyes, and 30 (4.3%) were hybrids; electrophoretic analyses indicated that 625 (88.8%) fish were saugers, 50 (7.1%) were walleyes, and 29 (4.1%) were hybrids. Clear discrepancies between the morphological and electrophoretic analyses affected at least 43 (6.1%) fish. Only 2% of saugers were hybrids, but at least 14% of walleyes possessed sauger alleles. Polymorphism at the PGM-1* locus in Peoria Pool saugers was also identified. We recommend electrophoretic screening for hybrids if saugers or walleyes are collected for use as broodstock from waters where they co-occur.

Growth of Hybrid Sunfishes and Channel Catfish at Low Temperatures

Abstract The growth of hybrid sunfish (male bluegill, Lepomis macrochirus x female green sunfish, L. cyanellus) and channel catfish (Ictalurus punctatus) below 15 C was determined in ponds on natural food and in cages on artificial feed. In all cases, the hybrids gained weight, while the channel catfish lost weight.

Supplemental Feeding of Hybrid Sunfish Populations

Abstract When stocked at high densities in ponds and fed Purina Trout Chow, F1hybrids of male redear (Lepomis microlophus) X female green sunfish (L. cyanellus) used supplemental food poorly and growth was unsatisfactory. F1hybrids of male green sunfish X female bluegill (L. macrochirus) utilized supplemental food readily and produced populations that had high percentages of catchable fish at the end of the first year of feeding. Males of the latter hybrid grew at a significantly higher rate than did the females. Conversion values were comparable to those obtained in feeding channel catfish.