Adult and juvenile paddlefish in floodplain lakes along the lower White River, Arkansas

Sandra J. Clark-Kolaks, John R. Jackson, and Steve E. Lochmann

Eleven floodplain lakes in the lower White River, Arkansas were sampled using a boat electrofisher and gill nets during periods of river connection (April–May 2004) and disconnection (June–July 2004 and 2005). Environmental characteristics, including water quality and lake morphometrics were concurrently measured in each lake. Average measures of connectivity were calculated for the preceding 5-year period. Of the 11 lakes sampled, 7 lakes contained paddlefish. A total of 44 paddlefish were observed during the study, but only one was observed during the period of river connection. Eye-fork lengths ranged from 348–1040 mm (n = 38). Paddlefish ranged in age from 3–19 years (n = 27). Paddlefish were more likely to be found in long narrow floodplain lakes which connected to the river early in the year. Paddlefish catch per unit effort increased as lake surface area and dissolved oxygen increased. Catch per unit effort increased as the variability in the start date of connection increased. Our research indicated that both juvenile and adult paddlefish use White River floodplain lakes, despite the risk of being isolated in lakes for long periods or during spawning seasons.

TANK CULTURE OF SUNSHINE BASS FINGERLINGS WITHOUT USING ROTIFERS

Gerald M. Ludwig and Steve E. Lochmann

A previously reported protocol for culture of sunshine bass (female white bass Morone chrysops X male striped bass M. saxatilis) larvae to fingerling size in tanks involved an initial feeding of rotifers for several days before the larvae were weaned to Artemia nauplii and prepared feed. Maintaining rotifer cultures requires space, time, equipment, supplies, and trained culturists. The rotifer cultures are often unstable, which increases risk of poor sunshine bass fingerling production in tanks. Elimination of the use of rotifers would greatly enhance the feasibility of reliable tank culture of fingerlings and should reduce production cost. This experiment compared three treatments with three replicates per treatment. In one treatment larvae were initially fed rotifers (Brachionus plicatilis) and then weaned to Artemia nauplii (0.48 mm X 0.19 mm). In a second treatment larvae were fed Artemia nauplii throughout the experiment. In a third treatment larvae were fed microcyst Artemia nauplii (0.43 mm X 0.18 mm) for the entire experiment. Sunshine bass larvae, 4 days post hatch (dph), were stocked into 100-L tanks at 75 larvae/L. Larvae were fed according to the three treatments to 14 dph. Survival was significantly higher for larvae fed rotifers and Artemia nauplii and larvae fed microcyst Artemia nauplii (93.6% and 37.9%, respectively) than for survival (4.3%) of larvae fed only Artemia nauplii. Larvae (7.13 mm standard length (SL)) fed rotifers and Artemia nauplii and larvae(7.26 mm SL) fed microcyst Artemia nauplii were significantly longer than larvae (6.86 mm SL) fed Artemia nauplii. This experiment is the first time that sunshine bass have been cultured to 14 dph on Artemia nauplii without rotifers at first feeding.

EFFECT OF TEMPERATURE ON LARVAL SUNSHINE BASS GROWTH AND SURVIVAL TO THE FINGERLING STAGE 

Gerald M. Ludwig and Steve E. Lochmann

Determining the optimum conditions for tank culture of sunshine bass fingerlings will facilitate a year-round supply of seed for the production cycle of this increasingly popular food fish.  This study determined the relationship between temperature and larval sunshine bass growth and survival to the time when fish were trained to accept commercial feeds.  Four-day post-hatch (dph) larvae were stocked at five temperatures from 20-32°C at 3°C increments. There were two replicates of each temperature. The larvae were fed rotifers through 8 dph.  Conversion to an Artemia nauplii diet began at 6 dph and training to dry starter feed began at 20 dph.  At harvest, average total length and average weight of the fish increased in a linear relationship with temperature while relative survival and number of fish harvested decreased linearly with temperature.  Tank yield had a curvilinear relationship with temperature. The temperature that provided maximum yield was 23.1°C. Although growth was faster at warmer temperatures, relative survival and yield were not.  These relationships between tank culture conditions and production characteristics support optimization of tank culture to meet specific production goals.  This should eliminate some of the logistical constraints to expanded tank culture of sunshine bass fingerlings.

PROPAGATION AND REARING METHODS FOR YELLOWCHEEK DARTER ETHEOSTOMA MOOREI

Calvin Fisher, Steve E. Lochmann, Mitch Wine, and Sherry Shoults

Yellowcheek darter Etheostoma moorei is found only in the shallow, high gradient riffles of the tributaries of the Little Red River in Arkansas.  Over the last twenty years E. moorei has undergone a massive decrease in population.  E. moorei was listed as a candidate species for addition to the Federal Endangered Species List in 2001.  Our goal was to develop a successful propagation method, and once propagation had occurred to develop and effective feeding schedule to culture E. moorei larvae.  Adults were captured from the wild using kick seining or snorkeling methods.  Two females and one male were stocked into 57-L recirculating aquar ia and fed a diet of blackworms 2-3 times per day.  They were monitored continuously to observe spawning activity and to determine when spawning had occurred.  When spawning was observed, the eggs were photographed at scheduled intervals until hatching occurred.  Larvae were passively collected from the adult aquaria using the surface overflow as they swam up.  Larvae were transferred to the 1.5-L black round rubber rearing tubs.  The larvae were photographed every two days. Larvae were initially fed a mixture of saltwater rotifers (Brachionus plicatilus) at a rate of 10/mL, Nannochloropsis algae paste, and artificial plankton.  Once they reached a large enough size, they were fed a mixture of rotifers (10/mL) and microcyst Artemia nauplii (2/mL).  Three larvae survived long enough to develop pigmentation and a benthic behavior.

THE EFFECTS OF STOCKING HATCHERY REARED LARGEMOUTH BASS ON THE 2007 YEAR CLASS OF WILD LARGEMOUTH BASS IN BACKWATERS OF THE ARKANSAS RIVER

Jeffrey R. Horne and Steve E. Lochmann

FISH ASSEMBLAGES ON GRAVEL BARS IN THE ARKANSAS RIVER

Lael Will and Steve E. Lochmann

We examined temporal and spatial variability of fish assemblages on 18 gravel bars in the Arkansas River.  The influence that specific environmental variables, such as water quality and substrate composition, have on fish assemblage structure was also examined.

Gravel bars were stratified by depth and distance from an upstream lock and dam.  Fish assemblages on each gravel bar were sampled six times.  Each sample consisted of duplicate trawls using a 3-m Herzog Armadillo trawl.  Water quality parameters were measured in conjunction with fish sampling.  Substrate samples were collected on each gravel bar using a standard Ponar dredge.  The fish assemblages on gravel bars in the Arkansas River are primarily dominated by juvenile Ictalurids, Cyprinids, and Centrarchids.  Of those, juvenile blue catfish, channel catfish and silver chub were the most abundant.  Fish species richness was significantly different between shallow and deep gravel bars (P < 0.0001) and among the seasons (P < 0.0001).  Catch per unit effort (CPUE) for the three most abundant species was analyzed for differences among depths, distance strata, and seasons.  There were differences in CPUE among depths (P = 0.03) and seasons (P < 0.0001) for blue catfish.  There were differences in CPUE among depths (P = 0.01, P < 0.0001), distances (P =0.04, P < 0.0001), and seasons (P < 0.0001, P < 0.0001) for channel catfish and silver chub.  The spatial and temporal variability in fish assemblage structure suggests that shallow gravel bars during the summer and fall seasons may be important habitat for some fish species. 

CHANGES IN SPORT FISH CHARACTERISTICS AND BIOMASS OF AQUATIC VEGETATION BEFORE AND AFTER BIOLOGICAL CONTROL OF VEGETATION IN SOUTHERN ARKANSAS

Brett Timmons and Steve E. Lochmann

The Ouachita and Saline Rivers, creeks, sloughs, lakes, and swamps cross Felsenthal National Wildlife Refuge (FNWR), the world’s largest green-tree reservoir.  The Refuge has developed an aquatic vegetation problem that hinders angler access and has reduced public visits.  The three most abundant aquatic vegetation species are American lotus Nelumbo lutea, hydrilla Hydrilla verticillillata, and coontail Ceratophyllum demersum.  Aquatic vegetation reduces predator-prey encounter rates, so largemouth bass Micropterus salmoides condition and growth can decline.  We sampled fish and vegetation from the FNWR.  Largemouth bass and bluegill were sampled with a boat electrofisher.  Twenty-meter transects and 1-m² quadrats were used to determine vegetation cover and biomass.  The mean (SD) CPUE of largemouth bass was 11 (12) fish/hr and the mean CPUE of bluegill was 59 (75) fish/hr.  The mean percent cover was 19 (35)% and the mean biomass was 93 (232) g/m².  Twenty-five centimeter grass carp Ctenopharyngodon idella were stocked at a rate of about 5 fish/ha.  The fish and vegetation assessments will be repeated in the future to determine changes in those communities due to biological control of vegetation.

Maternal and Paternal influences on larval production characteristics of white bass

Steve E. Lochmann, Kelly J. Goodwin, Matt McEntire, and Adam Fuller

Domestication of white bass Morone chrysops makes selective breeding programs possible.  Selection could be based on favorable larval characteristics, such as size at hatch or size at yolk absorption.  We conducted a diallelic study using five female and five male white bass.  Eggs from each cross were examined for fertilization.  Twenty fertile eggs from each cross were placed into individual vials and incubated at 18 °C until hatching.  Temperatures of the vials were measured daily.  Fertilization and hatch rates were calculated for each cross.  The remaining eggs from each cross were placed in individual McDonald hatching jars and allowed to incubate at 18 °C in recirculating systems.  Water quality (DO, pH, TAN, and hardness) of the recirculating systems and the vials was tested daily, and temperature was taken every 6 h in the systems until hatching was complete, then once daily thereafter.  Fifty yolk-sac larvae from each cross were photographed within 3 h of hatching.  The remaining larvae were allowed to develop in 75-L aquaria for 5 d.  Fifty larvae from each cross were photographed at 5 dph.  Fertilization rates ranged from 39% to 100%.  All eggs from one female failed to hatch, so hatch rates ranged from 0% to 50%.  Average (SD) temperature of the vials was 18.5 (0.3) °C.  There were no significant differences in temperature among the vials.  Average temperature of the recirculating systems was 18.6 (0.8) °C.  There was no significant difference in temperature, dissolved oxygen, pH, or hardness among the recirculating systems.  The TAN varied significantly (F = 4.03, df = 4, P < 0.05) among recirculation systems, but un-ionized ammonia was only 0.001 mg/L.

Standard length of larvae ranged from 2.66 to 2.94 mm at hatch, and from 3.47 to 4.22 mm at 5 dph.  Length at hatch varied significantly among female brood stock (F=113.52, df=3, P<0.001) and male brood stock (F=3.46, df=4, P=0.008).  The interaction term was also significant (F=4.49, df=12, P<0.001).  Length at 5 dph varied significantly among female brood stock (F=363.85, df=3, P<0.001) and the interaction between males and females was significant (F=21.05, df=12, P<0.001).  There was a 0.7 mm difference in length between the fastest growing cross and the slowest growing by 5 dph.  These results suggest improvement in larval characteristics might be possible through brood stock selection.

Optimizing feeding strategies for tank culture of sunshine bass using microcyst artemia nauplii as an intermediate step between rotifers and standard Artemia Nauplii

Steve E. Lochmann* and Gerald M. Ludwig

Tank culture of sunshine bass larvae has typically required rotifers at the time of first feeding.  Recently, sunshine bass larvae have been cultured without rotifers, by using Artemia nauplii from microcysts at first feeding.  Survival rates of 43% have been reported culturing sunshine bass larvae on microcyst Artemia nauplii alone.  We wanted to see if survival and growth of sunshine bass larvae would be improved by including rotifers (Brachionus plicatilis), microcyst Artemia nauplii, and standard Artemia nauplii in sequence during a production run.  This experiment was comprised of three treatments with three replicates per treatment.  Sunshine bass larvae, 4 dph (4.0 + 0.1 mm SL), were stocked into 100-L recirculating tanks at a rate of 75 larvae/L.  The first feeding treatment was rotifers (40/mL) followed by standard Artemia nauplii (8/mL).  The second feeding treatment was microcyst Artemia nauplii (20/mL) followed by standard Artemia nauplii (8/mL).  The third feeding treatment was rotifers (40/mL) followed by microcyst Artemia nauplii (4/mL) followed by standard Artemia nauplii (8/mL).  By day 8, all of the feeding treatments were fed standard Artemia nauplii only.  Water quality (DO, pH, TAN, and hardness) of the recirculating systems was tested daily.  Fingerlings were harvested on day 21 of the experiment.  Survival was determined gravimetrically.  Thirty larvae from each tank were photographed at the end of the study.  Standard lengths of larvae were determined using image analysis software.  We compared survival and growth among treatments using single factor analyses of variance.