Our farm operation consists of 157 total acres. 61 acres is tillable, 30 acres is a water-filled quarry, 24 acres is wooded, and the remaining acreage is scrub brush. Some of the tillable acreage is currently in CRP and CREP consisting of border quail buffer, filter strips, and windbreaks. The remaining tillable ground is used for bean and wheat production. The farm is owned jointly with my brother, Tim. We both hold non-farm jobs and work full time in addition to managing our property. Prior to this grant, we did not carry out any additional sustainable practices.
We wanted to utilize the 30 acre quarry as a water source for production purposes, so we began exploring aquaculture possibilities through the local Ohio State University (OSU) Extension Office. Baitfish culture was a hot topic at the time and OSU was surprised to find that we had a natural population of spotfin shiners. They encouraged us to explore the possibility of culturing the shiners as an alternative baitfish to market in the Lake Erie region. Because the spotfins had only recently been approved for sale as baitfish in Ohio, there was very little information available regarding culture techniques. OSU encouraged us to pursue this grant to begin studying culture techniques and methods. Utilization of the quarry required the use of mobile net pens to contain brood stock for both egg harvesting and grow out. In order to provide year round production, propagation would also be required year round. Recirculation systems constructed indoors would be necessary to maintain the brood stock, acquire eggs, hatch eggs, and provide grow-out for fry.
PROJECT DESCRIPTION AND RESULTS
The following description is for grant year 2007, which is a repeat process of grant year 2006. Please see interim annual report for 2006 grant year information.
Our indoor operation consisted of 6 aquariums and two nursery tanks. Two aquariums (30-gallon and 26-gallon) were used for brood tanks. Two other aquariums (10 gallons each) were used for growing algae. The remaining two aquariums (26 gallons each) were used for intermediate grow-out tanks. The two nursery tanks consisted of two 40-gallon shallow rectangular fiberglass tanks. Each nursery tank was connected to its own 30-gallon bio-filter that was constructed from 40-gallon water softener tanks. The nursery tanks were used to hatch the eggs, to grow the larval fish out of the larval stage, and to feed train the fry.
Goal: The overall goal of this research project was to find a cost-effective culture of a baitfish species to resolve the shortage of baitfish in northwest Ohio in the fall months of the year. In order to accomplish this, we knew that year round culture of the baitfish species would be necessary in this region.
Our plan was to catch a supply of brood stock and winter them over in captivity. At a predetermined time we would manipulate the photoperiod and water temperature to encourage spawning activity. After spawning occurred, the eggs would then be hatched and the fry would be feed trained. When the fry reached appropriate size, they would be moved to small net pens at our quarry for grow-out. The minnows needed to be 1.75 – 2.25 inches by October to be considered market size.
Process: The spotfin shiner was the minnow of choice due to availability, hardiness, and the fact that it is a native species. It is also similar in size and color to the emerald shiner, which is utilized almost exclusively for perch fishing during the fall months. We caught 30 spotfin shiners with a cast net in late November and held them in the brood tanks. No more than fifteen minnows were put into each brood tank to maintain water quality and minimize the likelihood of disease. The minnows were caught late in the fall to allow the minnows to go through a period of cold stratification and rest after the summer spawning period. The water temperature in the quarry was 45 0F at the time of acquisition. We kept the water temperature in the brood tanks as low as possible (60 0F) to prevent spawning activity until February. We chose the month of February to begin attempting spawning activity in order to appropriately allow for grow-out time and eventual placement into the quarry.
During the stratification period, we designed and fabricated the nursery tanks, constructed egg transfer devices (ETDs) that were similar in construction to hester-dendy Macro-invertebrate substrate samplers, and attempted to start the algal culture tanks. The nursery tanks had three compartments. The first compartment received the filtered water from the bio-filter and held the ETDs while the eggs hatched. The water flowed from the first compartment over a divider into the second compartment. The water flow was used to carry the new larval minnow from the first compartment to the second compartment. The second compartment was used to hold the larval minnows where they were feed trained during the transition from their yolk sac to commercial feed or plankton. The third compartment was separated by a partition with a 180 micron screen at the top. Compartment three was the return area where water circulated back to the bio-filter.
On February 2nd the water temperature in the brood tanks was slowly raised until February 15th when the temperature reached 74 0F. Four ETDs were placed in each brood tank and by March 4th, each brood tank had eggs in the ETDs. The ETDs in brood tank #1 were moved to nursery tank #1. The ETDs in brood tank #2 were moved to nursery tank #2. Nursery tank #1 was fed an algal culture and nursery tank #2 was fed a crushed flake food. After 5-6 days the eggs began to hatch. The egg production process was continued until April 8th. At the end of the egg production process, nursery tank #1 had an estimated 730 eggs introduced and nursery tank #2 had an estimated 1900 eggs introduced.
Most of the eggs that were introduced into the first compartment of each nursery eventually hatched. The larval minnows swam to the surface and were washed into the second compartment. We intended to feed nursery tank #1 a live plankton diet. Since we had trouble producing an algal bloom, we fed nursery tank #1 a mixture of live plankton and commercial food. Nursery #2 was fed solely commercial food.
When the minnows were large enough to be caught with an aquarium dip net, they were transferred into two intermediate grow-out tanks. Both tanks were fed a mixture of commercial foods to provide a diverse diet in an attempt to prevent lordosis or scoliosis, which was encountered during the first year. The minnows were held in the intermediate grow-out tanks until all of the minnows were large enough to be transferred from the nursery tanks into the grow-out tanks.
On May 15th we started to adjust the pH and salinity of the intermediate grow-out tanks to match that of the quarry. On June 16th we began transfer of the minnows to a floating net pen at the quarry. The net pen flotation rings were constructed out of PVC pipe and were the following dimensions: 6ft.L x 4ft.W x 4ft D. The nets were fabricated to our design specifications by Memphis Net and Twine, with opening sizes of 1/16 in. and 3/32 in. By June 21st we transferred approximately 675 minnows. The net pens were covered with snow fence to keep the predatory birds out. While in the net pens the minnows were fed the same diverse diet for a couple of weeks. After two weeks the same food was mixed with food (#1 crumble Silvercup 38-8) from a local supplier. After another two weeks the minnows were fed only the Silvercup #1 crumble food. The juvenile minnows were fed once a day during the week and two to three times a day on the weekend throughout the summer months. Routine maintenance was required to keep algae from fouling the nets, thereby maintaining adequate water movement to replenish oxygen and remove wastes. This was accomplished by brushing the nets periodically, both inside and outside, with a nylon brush. No water quality issues were observed in the net pens thoughout the summer grow-out period. In September, severe storms hit our area and partially sunk a net pen, causing the release of the minnows that were initially cultured indoors. Because we lost the minnows, we were unable to obtain final project information regarding total numbers and average length and weight. However, the majority of the minnows had reached market size or larger based on visual observation. Mortality losses were minimal and primarily due to predatory birds.
We worked primarily with Shawn McWhorter from the Ohio State University (OSU) Extension office. Shawn provided guidance for the construction of the nursery recirculation system. We also consulted Shawn for help with the algal culture tanks, food for the larval minnows, and water quality testing. While working on our project, we also assisted Shawn in his new research projects involving the spotfin shiner. Shawn is already utilizing the concepts developed in our project to duplicate results on a larger scale. Fred Snyder from Ohio Sea Grant was also consulted regarding his initial research into the spotfin shiner. The ETD devices we constructed were a modification of Fred’s original designs.
The results of the research were both good and bad. While we were able to induce spawning during the off-season, the project experienced a high mortality rate at the larval stage in both nursery tanks. Some of the larval minnows took to the commercial feed and some did not. Although this is a common phenomenon while attempting to feed train fish, the rate was excessive in nursery tank #1 due to a poor algal culture feed. In order to minimize the mortality rate in nursery tank #1, we reduced the number of fry, added commercial feed along with algal culture feed, and monitored water quality parameters very closely. Those larval minnows that immediately took to the commercial feed greatly increased their chances of survival. A very high percentage of the minnows that were transferred to the intermediate grow-out tanks survived, so the feed training process is extremely critical for success. It should also be noted that mortality rates were likely increased due to cannibalism. Since the spotfin shiner is a fractional spawner, we had some small minnows late in the hatching process that were introduced into the intermediate grow-out tank and were subsequently eaten by the larger juveniles.
Feeding the juveniles a diverse mixture of ground fish food appeared to prevent most of the lordosis and scoliosis that was experienced the year before. Some deformity still occurred but it was limited to less than 10 minnows in the-grow out tanks.
We experience trouble getting a good algal bloom, which forced us to feed the larval minnows in nursery tank #1 a commercial feed. Therefore we were not able to make any comparisons between a live plankton diet and a commercial food diet. This research will be continuing at OSU’s facilities.
We found it troubling to introduce significant food quantities into the culture environment and still maintain the high level of water quality needed to prevent mortality. This was especially true in the nursery tanks, where fine particulates can easily foul the gills and prevent oxygen transfer. The fine filter screen we used between the second and third compartment fouled quickly. We have found that a larger mesh could be used without the larval minnows passing through and getting trapped in the bio-filter.
The rate of growth during the grow-out process was good. The average size of the minnows was .75 inches when they were transferred to the net pens in June. The growth rate slowed in the net pens due to the reduced feeding. Although the feed rate was reduced, the minnows easily reached market size by September.
In conclusion, this researched demonstrated that the spotfin shiner can be held in captivity and successfully spawned during the winter months. The hatchery and nursery must have a robust and specialized filter in order to maintain water quality. The filtration system should be able to separate the micron size larval minnows from the micron-size food and waste in order to be successful. A high mortality rate during feed training with a commercial food might be overcome by using a live plankton diet solely or in combination with commercial feeds. Because the spotfin shiner is a fractional spawner, a large brood stock needs to be maintained. This will allow for a large number of eggs to be produced at one time, which will minimize labor, cannibalism losses, and size grading. With the proper diet and nursery conditions, the small fry that survive to grow-out stage can be cultured to market size in time to meet the high demand for minnows in the fall fishing season. The proper diet will also prevent growth deformities. Further research needs to be conducted to address the transfer from feeding from the yolk sac to feeding on commercial feed.
Grow-out in the net pens was very successful, with the exception of the flotation failure near the end of the project. Backup flotation will be attached to net pens in the future to prevent this situation from occurring again. Introduction of automatic feeders earlier in the process (nursery stage through final grow-out) will reduce time and labor requirements and likely increase growth rates. Because minnows were successfully spawned and grown to market size by fall using recirculation systems and net pens, we have demonstrated that the quarry can be used on our farm for the production of baitfish and possibly other marketable species. Further work will be needed to move this process into a production size operation. This work is planned for the 2008 season at OSU’s extension office near our farm. They plan to perform baitfish feed studies and pond rearing protocols for baitfish, including the spotfin shiner.