Nutrient Management in Commercial Baitfish Ponds
Nathan Stone, Alex Kachowski and Hugh Thomforde

A priority problem identified by baitfish producers is management of algal density.  In some cases, farmers have difficulties obtaining a bloom, while dense blue-green algae blooms are often problematic later in the season. Given the particular soils and source waters in Lonoke and Prairie Counties , old and shallow culture ponds, and a long history of diverse and often intense fertilization practices among baitfish operations, development of appropriate fertilization recommendations is particularly challenging. In this project, we are surveying chemical and physical characteristics of surface sediments and water sources of commercial baitfish ponds and utilizing the algal bioassay method to develop fertilization recommendations leading to the establishment of desired bloom densities in ponds while avoiding unnecessary or excessive applications of nutrients. 

Developing Hatchery Management Techniques for Baitfish
Ashlee Paver and Nathan Stone

Commercial production of rosy red fathead minnows in outdoor ponds is problematic, as farmers have little control over fish densities. Based on their success in tank hatching eggs of other species, producers are interested in a similar system for fathead minnows. Efficient methods of fathead minnow egg collection and removal will be required before indoor hatching of eggs becomes a commercial practice. This research compares egg production from two different substrate designs, and compares various fungus treatments for incubating eggs. 

Factors Controlling Growth in Commercial Baitfish Species
Marcella Melandri, Nathan Stone and Greg O’Neal

Baitfish are sold by size category, and control of fish growth is essential for farmers to meet market goals. This project examines some of the basic factors controlling golden shiner growth in aquaria. The first study compared growth of golden shiners at three densities and found that increasing fish density did not significantly reduce fish growth, indicating that there are no behavioral limitations. Two 10-week trials determined the growth and feed conversion efficiency of two sizes of golden shiners at four different temperatures (15, 20, 25 and 30 C).

The Effects of Diets with or without Menhaden Fish Meal and Oil on Spawning Adults, Eggs and Fry of Fathead Minnow (Pimephales promelas)
Rebecca Lochmann, Todd Sink and Harold Phillips

The objective was to determine the main and interactive effects of dietary protein sources (plant versus animal) and lipid sources (poultry versus fish oil) on fathead minnow broodstock, and egg and larval quality. Rosy red fathead minnow broodstock in outdoor pools were fed practical diets containing 10% lipid as poultry fat or menhaden fish oil in combination with animal proteins (poultry + fish meals) or plant proteins. Fish received the diets for 2 months prior to spawning, which began in late February. Egg diameter, egg fatty acid composition, hatching percentage, and larval length were determined. There were no differences in egg diameter, hatching percentage, or larval length due to diet, despite pronounced differences in fatty acid composition of the eggs from adults fed diets with different lipids. Results indicate that poultry fat and vegetable proteins are suitable feed ingredients for broodstock diets of fathead minnow in outdoor systems, as no improvements in the quantity or quality of eggs and fry from fish fed diets with animal proteins or marine fish oil were observed. Vegetable proteins and poultry fat are less expensive. 

Effects of a Feed Additive, Lipid Concentration, and Protein Source on Performance of Golden Shiner (Notemigonus crysoleucas)
Rebecca Lochmann, Todd Sink and Harold Phillips

The objectives were to determine whether practical diets supplemented with Grobiotic® -A , extra lipid, or both could improve growth, survival, feed conversion, body composition, or survival upon exposure to low dissolved oxygen. Six diets similar to a commercial diet (30% protein and 9.6 kg energy/gram of protein) were formulated. Two diets contained the same protein components (primarily fish and poultry meals) and differed only in the amount of added lipid (4 vs. 10% poultry fat). The diet with 4% fat was the control. Two other diets were similar to diets 1 & 2 except they contained 2% Grobiotic® -A. Two additional diets contained poultry meal in place of fish meal on an estimated digestible protein basis. Final weight gain did not differ by diet. Survival was not differentially affected by dietary treatment. Fish fed diets with GROB or No FM-4% PF had slightly lower FCR than fish fed other diets. Post-trial fish were exposed to low dissolved oxygen for 24 hrs, but no mortality occurred. There were no differences in whole-body proximate composition due to diet. A feeding trial in pools was conducted with the same diets. Results were similar to the tank study. A subset of fish was grown to a larger size in netpens for analysis of alternative complement activity. There were no differences in activity between fish fed diets with or without Grobiotic® -A. 

Mortality Rates in Golden Shiner, Notemigonus crysoleucas, Fed High-Fat Diets with or without a Dairy/Yeast Prebiotic Prior to Challenge with Flavobacterium columnare.
Rebecca Lochmann, Todd Sink and Harold Phillips

The objectives were to determine if a high-fat diet alone or supplemented with a dairy-yeast prebiotic could decrease mortality rates of golden shiners subjected to Columnaris challenge. Diets were as described in the preceding project. After the feeding trial fish were exposed to Columnaris in a controlled bacterial challenge. Mortality in the 4% poultry fat (41.7 ± 12.9%) and 10% poultry fat (40.0 ± 6.1%) diets was high and not significantly different (P > 0.05). Mortality for the dairy-yeast prebiotic (6.7 ± 2.7%) diet was much lower and significantly different (P < 0.05) from the 4% and 10% poultry fat diets. Thus, the dairy-yeast prebiotic effectively reduced mortality rates in golden shiners exposed to columnaris, but a high-fat diet alone provided no protection relative to the lower-lipid control diet. Prebiotics give producers the potential to control columnaris outbreaks in golden shiners without having to use antibiotics. 

Dairy/Yeast Prebiotics Reduce Mortality in Stressed Golden Shiners, Notemigonus crysoleucas, Challenged with Flavobacterium columnare.
Rebecca Lochmann, Todd Sink and Harold Phillips

The objective was to evaluate the effects of columnaris disease challenges on golden shiners with access to natural foods in outdoor pools. The shiners were fed a control diet or a 2 % dairy-yeast prebiotic diet for 10 weeks prior to a columnaris challenge. In trial one, golden shiners from eight pools were stocked into different aquaria (experimental replicates were maintained), subjected to confinement stress or left unmolested (trial two), and exposed to Columnaris bacteria. Mortality (mean ± SE) was not significantly different for control diet (23.4 ± 3.4 %), prebiotic diet (10.0 ± 3.3 %), or prebiotic diet with stress (16.7 ± 3.4 %) treatments. Mortality for the control diet with stress (50.0 ± 3.3 %) treatment was significantly greater than the other treatments. Prebiotic supplementation in golden shiner feeds prior to a stressful event can reduce associated mortality from columnaris by greater than 50 % compared to control diets. Gives producers the potential to control stress related disease outbreaks in golden shiners without having to resort to antibiotics. 

Development of a Whole-body Cortisol Extraction Procedure for Determination of Stress in Golden Shiners, Notemigonus crysoleucas.
Rebecca Lochmann, Todd Sink and Harold Phillips

The objective was to develop and validate methods for whole-body cortisol extraction from individual baitfish. Three types of extracts were tested: 1) an ethyl ether unaltered extract; 2) an extract reconstituted in phosphate buffered saline; and 3) an extract that had been increased in volume by addition of food grade vegetable oil. These extracts were evaluated using validation tests with radioimmuno assays (RIA) and enzyme-linked immunosorbent assays (ELISA). The unaltered extract produced inadequate volumes of extract for multiple assays, and could not be used for determination of cortisol in a single fish.  Use of a vegetable-oil volume boosting method provided a means for determination of cortisol from individual baitfish using either RIA or ELISA assays. We now have a reliable method of determining if production practices are stressful to golden shiners and other baitfish, to better refine practices to deliver a healthier, livelier product.