The fish culture research team evaluates potential solutions to problems faced by hatchery staff through carefully designed experiments. The purpose of culture research is to increase the efficiency and productivity of DNR hatcheries through research.
Walleye Culture Research, Making a Great Product Better!
Better Disease Managment in Fish Production
In 2012, performace and survival of lake and river strain fry 3 to 35 day post hatch fed Otohime diets was compared to pond raised fry. Evaluation of vitamin D supplement top dressed onto Otohime diets fed to each strain was also compared to Otohime diet without supplemental vitamin D coating. Growth and survival of fry fed the vitamin D diet was similar to the performance of fry fed the noncoated control diet, regardless of fry strain. Survival of river strain fry (75.8%) was greater than the survival of lake strain fry (66.7%) to 35 days post hatch. However, fry produced by intensive culture were 0.67 g and larger than those produced in ponds which were 0.47 to 0.56 g. Intensive fry culture method offers an alternative to pond production and results in good survival rates and predictable growth rates.
Alternative diets for feeding walleye from fingerling to fall stocking size were also compared in 2012. Standard WG 9206 was compared to an experimental WG formula with poultry meal replacing some fish meal and a Salmon diet. At the end of the 70-day trial, walleye fed WG 9206 were significantly longer than walleye fed WG experimental or salmon diet, by 5.4 mm and 12.3 mm, respectively.
Diseases in fish hatcheries can lead to mortality and reduced growth rates which reduce efficiency and limit numbers and quality of fish produced for Iowa’s fisheries. Effective disease management and treatment is therefore essential. This research has established a system of monitoring and treatment used by hatchery staff to apply formalin judiciously resulting in cost savings and production of healthy fish.
Managing Ponds for Improved Hybrid Striped Bass Production
The purpose of this study is to examine concerns related to fry transportation and fish production techniques and to develop a management plan for production of HSB in both plastic-lined (Rathbun) and earthen (Mt. Ayr) ponds. This plan will include best management practices for: 1) transporting fry, 2) timing of initial stocking, 3) recommended stocking densities, 4) pond fertilization regimes, and 5) water quality management. In the 2012 culture season four trials were conducted, two evaluating fry transport methods, one evaluating the necessity of pond fertilization, and the fourth comparing the hybrid crosses.