PROPAGATION AND REARING METHODS FOR YELLOWCHEEK DARTER ETHEOSTOMA MOOREI

Steve E. Lochmann, Lael Will, and Mitch Wine

In July of 2010, the U.S. Fish and Wildlife Service proposed endangered status for the yellowcheek darter Etheostoma moorei. Declines in population have been attributed to habitat loss and low water levels over the past 20 years. E.moorei is endemic to Arkansas, occurring only in tributaries of the Little Red River. We developed a successful propagation method and an effective feeding schedule to culture E. moorei larvae. Broodstock were captured from the wild and held in four 75-L recirculation tanks. Two females and one male were stocked into each tank, and were fed black worms once per day. From May 11 – July 10, we observed approximately 17 spawning events, which yielded 512 larvae. Larvae were passively collected from adult aquaria using the surface overflow as they swam up. Larvae were stocked into 5-L plastic buckets. From 1-10 dph, larvae were fed a combination of APR (Artificial Plankton^.Rotifer, Ocean Star International, Inc., Snowville, Utah), Nannocholoropsis algal paste, and microworms four times/day. A peristaltic pump was used to feed a combination of APR, and Nannocholoropsis for 3 minutes every hour during a 24-h period. Larval yellowcheek darter

At 11 dph, saltwater rotifers Brachionus plicatilus and microcysts Artemia nauplii at a rate of 10/ml/day were added to the diet. At 18 dph Artemia, nauplii were added to the diet at a rate of 10/ml/day, and Nannocholoropsis was discontinued. At 25 dph instar 3 Artemia metanauplii were added to the diet, while artificial plankton, microworms, and saltwater rotifers were discontinued. At 32 dph, instar 5 Artemia metanauplii and fragments of chopped black worms were added to the diet. Microcysts Artemia nauplii were discontinued. Juveniles began exhibiting benthic behavior at 20 dph and were transferred to 5-L buckets with an undergravel filter. We estimate survival to 45 dph to be 50%. Growth rates to 70 dph averaged (SD) 0.19 (0.04) mm/d. Compared to previous years, spawning occurred more frequently and larval mortality was much lower. These methods proved successful for the propagation and rearing of E. moorei.

Hydrilla fouling boat prop 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 FNWR developed an aquatic vegetation problem that hindered angler access and reduced public visits. Fish sampling was performed in 2008 prior to vegetation control, and repeated in 2009 and 2010. Largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus were sampled with a boat electrofisher. Vegetation was sampled in 2008 prior to vegetation control and again in 2010. Twenty-meter transects and 1-m² quadrats were used to determine vegetation cover and biomass. Grass carp Ctenopharyngodon idella were stocked in late 2008 and early 2009 at a rate of 11 fish/ha. ANOVAs were used to compare fish population characteristics. Triploid grass carp A least significant difference test was used to compare differences in the mean pre-stocking and post stocking. Pre-stocking and post-stocking vegetation percent cover and biomass were compared using a percent similarity index. The pre-stocking mean (SE) CPUE of largemouth bass was 11 (0.9) fish/hr and the mean CPUE of bluegill was 40 (9) fish/hr. Post stocking mean CPUE of largemouth bass were 28 (4) and 30 (2) fish/hr for 2009 and 2010, respectively. Post stocking mean CPUE of bluegill were 81 (17) and 53 (4) fish/hr for 2009 and 2010, respectively. Post stocking relative abundance was significantly different for largemouth bass. Post stocking relative abundance for bluegill differed significantly in 2009. The pre-stocking mean percent cover was 12 (28)% and the mean biomass was 62 (163) g/m². The post-stocking mean percent cover was 34 (45)% and the mean biomass was 138 (346) g/m². The most abundant aquatic vegetation pre-stocking were American Lotus Nelumbo lutea, Hydrilla Hydrilla verticillillata, and Egeria Egeria densa. The most abundant aquatic vegetation species post-stocking were American Lotus, Water Lily Nymphaea odorata, and Coontail Ceratophyllum demersum.

Cannibal hybrid striped bass EFFECT OF FEED TYPE ON GROWTH RATE OF HYBRID STRIPED BASS

Steve E. Lochmann*, Lael A. Will, Candice L. Williams, Maya L. Warner, Avrion J. Williams, and Brett A. Timmons

The growth rate of hybrid striped bass may be a reflection of their feed type. Over the course of two one-week studies, large hybrid striped bass larvae were exposed to daily diets of formulated feed alone, smaller hybrid striped bass larvae alone, or both feed and larvae. Growth was examined at the end of each study. In study one, large larvae were 22 dph, averaging (SD) 12.8 (1.1) mm TL. Fifteen 3.87-L glass jars were filled with 3 L of dechlorinated water. Aeration was provided by individual aquarium pumps. Larvae were stocked at a density of four large larvae per jar in every jar. In jars with feeding treatments of larvae only or feed and larvae, ten smaller larvae were stocked. The number of smaller larvae was daily replentished to remain at a density of ten larvae per jar. Jars with treatments of feed only, and both feed and larvae, were fed twice daily ad libidum. Tank bottoms were siphoned and water quality was monitored daily. Salinity was kept at 1 ppt. In study two, large larvae were 31 dph, averaging 30.1 (2.2) mm TL. Replicated jar study Only one large larva was stocked in each jar, with three smaller larvae stocked in jars according to the same treatments as study one. In study one, growth rates ranged from 0.02 to 0.84 mm/d at 29 dph. There was no significant difference in growth among treatments (F = 1.18, df = 11, P > 0.05). In study two, growth rates ranged from 0.07 to 1.11 mm/d at 38 dph. There were significant differences among the treatments (F = 5.28, df = 11, P < 0.05). The growth rate of the feed and larvae treatment was 0.59 mm/d faster than the feed only treatment. Cannibalism in the larvae only treatment usually accounted for losses of 1-2 larvae/cannibal/day.

Cannibalism had a positive effect on growth rate. Large larvae exhibit faster growth because of efficient feeding and cannibalism. Overall losses to cannibalism are small relative to other sources of mortality. It is not clear that removing cannibals should be an important part of phase one fingerling production.

INFLUENCES OF MATERNAL PHENOTYPE AND AGE ON LARVAL PRODUCTION CHARACTERISTICS OF WHITE BASS

Steve E. Lochmann, 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. A combination of 3, 4, and 5 year old white bass were subjected to a 12-month photothermal regime. During the 12-month period, fish were fed a 45% protein diet twice daily to satiation. At the end of the 12-month period, fish were induced to spawn with hormone injections. Strip spawning white bass Weights and lengths of females were determined prior to hormone injection. Fish were injected with 330 IU HCG per kg body weight.

Ripe white bass females were strip-spawned. Eggs from one female were divided equally between two plastic containers. Eggs from a second female were also divided equally between two more plastic containers. Eggs in each of the containers were fertilized using milt from one of two different males, producing a 2 x 2 cross. This process was repeated nine times, such that a total of 18 females and 18 males were used during the spawning effort. Eggs were placed in individual McDonald hatching jars and treated with a 150 mg/L solution of tannic acid to reduce adhesion and minimize clumping. After treating with tannic acid for 10 min, the eggs were rinsed with well water. After 3 h of water hardening, a sample of eggs from each female was removed from the McDonald hatching jar and placed into a glass Petri dish. Individual eggs were examined with a dissecting stereomicroscope to determine fertilization rates. Fertilized eggs were placed individually into 6-ml vials filled with well water. The eggs in 6-ml vials were incubated at approximately 22-24° C. The remaining eggs were maintained in the McDonald hatching jars and incubated at 22-24°C. Eggs in vials were examined every 6 h until hatching was complete. Hatching percents were determined from the results of hatching in vials. After approximately 30 h, most embryos had either hatched or died. A qualitative assessment of hatching success in McDonald hatching jars was undertaken. On the day of hatch, approximately 40 larvae from each cross were preserved in 4% buffered formalin. At 5 days post hatch (dph), approximately 40 larvae from each cross were preserved in 4% buffered formalin. Preserved larvae were photographed individually. Larval standard length (SL) and fin fold length were measured for each larva. Standard length and fin fold length were added to determine larval total length (TL). The effect of female age on length at hatch was examined using an analysis of covariance (Proc GLM, SAS Inc.) with female weight utilized as the continuous covariate. The same statistical approach was used to examine the effect of female age on length at 5 dph. Altogether, three 3-year-old, thirteen 4-year-old, and two 5-year-old females were used during this study. Female weights averaged (SD) 614 (146) g and ranged from 400 to 890 g. Fertilization rates averaged 6 (6)% and ranged from 0% to 25%. Hatch rates were fairly low (< 10%) for most crosses. A total of 11 females had enough hatching to collect adequate sample sizes for length at hatch estimates. Larvae from one of those 11 females all died before 5 dph. Length at hatch averaged 2.40 (0.27) mm. Length at 5 dph averaged 3.07 (0.31) mm. Neither female weight or female age significantly influenced length at hatch. Likewise, neither female weight or female age significantly influenced length at 5 dph.

Bow of electrofishing boat SPAWNING DISTRIBUTION AND POPULATION CHARACTERISTICS OF WHITE BASS IN POOL 4 OF THE ARKANSAS RIVER

Brandon W. Baker and Steve E. Lochmann

Spawning behaviors and dynamics of white bass Morone chrysops in the Arkansas River have not been documented. An assessment of the population would be integral to generating a science-based management strategy. We sampled white bass during their spawning season in the 10 primary tributaries found within Pool 4 in the Arkansas River . The pool was divided into three segments (upper, middle, lower). Each segment had three tributaries. Processing white bass otoliths Each tributary was sampled every third week during the spawning season to determine spatial variability. One tributary (Caney Bayou), known to be occupied by white bass during the spawning season, was sampled weekly to document temporal variability of the spawn. White bass were collected by boat-mounted electrofishing. The catch per unit effort (CPUE) averaged (SD) 6.2 (16.9) fish/h across the pool. The CPUE for Caney Bayou averaged 8.5 (20.3) fish/h. Caney Bayou was the most utilized site, but other sites were also utilized during the spawning season. Precipitation and temperature appear to influence spawning effort. Once water temperature reached 13°C, white bass activity near tributaries increased. In addition, there was a positive relationship between precipitation and the occurrence of white bass in a tributary. Overall gender ratio was 1 ♂:2 ♀, while the gender ratio in Caney Bayou was 1♂:3♀. Two indices of population size structure were calculated. The PSD was 68.9 and the PSD_P was 53.7. Average relative weight across all cohorts was 103 (23.5). The average TL for age-1 white bass was 204 (31.5) mm, and for age-3 white bass was 353 (21.3) mm. The oldest white bass collected was a 7-year-old. Total annual mortality was 49.3% using a catch curve regression. As habitat alterations occur and water allocations and releases are modified, understanding the critical habitats and conditions supporting favorable spawning and recruitment is imperative.