Improving Survival of Late Stocked Hybrid Striped Bass Fry
Nathan Stone, Alex Kachowski, David Heikes and Neil Pugliese, UAPB
Gerald Ludwig, ARS  

The objective of this study was to document the development of zooplankton blooms in ponds during the summer in response to two rates of pond filling. Ten, 0.04-ha earthen ponds at the University of Arkansas at Pine Bluff Aquaculture Research Station were used in this 21-d study. Ponds were filled in 4 or 8 d to a depth of 147 cm (at drainpipe) by raising the water level in equal increments each day within each treatment (36.6 cm or 18.4 cm/d). Ponds were fertilized with rice bran at a rate of 140 kg/ha (125 lb/acre) on the first day of filling (Day 1) and on Day 4, followed by applications of 28 kg/ha (25 lb/acre) every 3 to 4 d. Zooplankton were collected daily using a floating pump. Dissolved oxygen, temperature and pH were measured in each pond twice daily. Fluorescence (in vivo) was measured daily and chlorophyll a every 6 days. Total ammonia nitrogen (salicylate method) was measured each morning and nitrite-N (diazotization method), nitrate-N (dimethyl phenol method) and reactive phosphorus (ascorbic acid method) were measured twice a week. Water temperatures and light intensity were recorded hourly at two depths in three ponds of each treatment. Results of the study should provide valuable information on the appropriate filling rate and stocking time (relative to the start of pond filling) for the culture of fish fry during the summer.

Effect Of Temperature On Larval Sunshine Bass Growth and Survival to The Fingerling Stage
Jerry Ludwig and Steve 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.

Optimizing Feeding Strategies For Tank Culture of Sunshine Bass Using Microcyst Artemia Nauplii as an Intermediate Step Between Rotifers and Standard Artemia Nauplii  
Steve Lochmann and Jerry Ludwig

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. Average (SD) individual standard length of larvae was 9.08 (1.43) mm and ranged from 6.46 to 15.05 mm. Average length of larvae did not vary among treatments (F=0.81, df=2, P=0.489). Variability in survival among tanks was high. Survival ranged from 9% to 96%, and varied somewhat among treatments (F=3.41, df=2, P=0.102). The lowest two survival rates (9% and 12%) occurred in treatment two and the highest two survival rates (70% and 96%) occurred in treatment three. It appears that matching food size to larval size, as larvae grow, is likely to result in better survival. However, growth of larvae does not appear to improve similarly.