Dexter and Poplar Bluff, Missouri
Department of Plant Agriculture

Day 11 - Wednesday

Fish Production and Conservation

Date: Sept 6, 2017

By: Brett Hilker, Brett Reesor, Ted Vanhie, Britt Robinson, Tessa de Boer
The theme of today was fish production and wildlife ecosystems as it was related to conservation in Missouri. We started off the day with a visit to Chesapeake Fish Hatchery in Mount Vernon, Missouri, where we learned about the process of hatching and raising fish that will be released into public ponds once they reach a certain size. Next, we took a four-hour bus ride to Otter Slough Missouri Conservation Authority in Poplar Bluff, Missouri where we learned about waterfowl protection.

Chesapeake Fish Hatchery, Mount Vernon Missouri
Warm water hatcheryWe arrived at the Chesapeake Fish Hatchery and were greeted by Allison Leisenring who gave us a tour of the facilities. The hatchery was started in 1927 and was used for 50 years until the 1980’s when the hatchery underwent extensive renovations. It reopened in 1988 with modern facilities. There are four facilities like this one in Missouri, four cold water and four warm water. The facility we toured today was a warm water hatchery that produces 7 million fish per year. There are 13 one-acre ponds, 10 half-acre ponds, one four-acre solar pond, and fish production rooms. The facility sits on 40 acres and the total area consists of 113 acres. The rest of the land area serves as a habitat for wildlife.  

The numerous ponds are all spring fed. The water runs from the spring into a solar pond at 50-60°F. While the water sits in the solar pond, it is heated to 80-85°F to supply the water for the fishponds. The hatchery does not manage water quality the way we thought it might have. There are no water treatment protocols in place, however, dissolved oxygen readings are taken daily to ensure suitable water quality is maintained. The concentration of dissolved oxygen must stay around 7 parts per million (ppm). If the dissolved oxygen readings go below 7 ppm, aeration pumps in the ponds are used to increase the oxygen levels. If ice forms on the ponds during the winter, extra management is required because dissolved oxygen levels can dip below 7 ppm due to the reduced gas exchange between the air and water which can be detrimental to the fish. To avoid this from happening, holes are cut into the ice to allow for adequate gas exchange to maintain 7 ppm of dissolved oxygen. Other factors that can reduce dissolved oxygen concentration in the water are cloud coverage and rainfall.
Pond at the Chesapeake Fish Hatchery
After we got a sense of the facility and how it operated, Allison covered the feeding programs that corresponded with the different fish species. The feed contained 47% crude protein, which was sourced from soybean by-products. The feed also contained wheat and other fibers. The feeding is done by simply scattering the feed onto the ponds for the fish to eat. We were surprised to learn that the hatchery does not track average daily gain (ADG), feed efficiency or conversion rates and has no specific way to track the amounts of feed the fish are consuming. Allison explained that the reasoning behind not tracking these statistics is that hatcheries are not looking for high production, but healthy offspring and stock. The conservation personnel base the amount of feed they give the fish daily by the amount of feed left over from the previous day. If there was an ample amount of feed left over, they will reduce the feed by small increments. If there is no feed at all, they will add more feed for the next day.

We believed that the facility could be more efficient and cost effective if a new feeding program was implemented. Currently, the only difference in diet among the fish is by life stage. Younger fish receive more protein in their pellets, but if the diet was tailored more specifically for the species of fish and age then greater efficiencies could be achieved. For example, it may be possible to feed less because the nutrient content for that species is correct and the species requirements can be met with less feed. However, the hatchery has not strayed from their old feeding techniques, and the current feed contracts they have works well for their operation. Thus, they do not see a reason to change their current feeding practices. The most important component of feeding is the size of the feed pellets. If the pellets are too small, the feed could get lodged in the gills of the fish, creating a site for bacterial growth. However, there are consequences to the food pellets being too large; the fish will not eat the feed, which results in a waste of money, and the feed will settle at the bottom of the pond, potentially contaminating the water. The pellet size of the feed is therefore increased in relation to fish growth. The crude protein contents in the feed decreases because of the reduced requirement for protein in growth as the fish matures.  

Allison told us that they have never received any complaints about how they raise or handle their fish stock. Some fish are culled if they get too big because they are unable to produce healthy eggs. Any deadstock or culled fish are disposed of in a composting area located at the back of the property. The hatchery has never received complaints about odor from the compost pile, likely because it is quite isolated on a vast tract of land. When the ponds are drained, the water goes to settlement ponds, and then clean, filtered water can overflow into the river. Neighbours sometimes complain about higher water levels in the river, but seldom do they receive complaints about river water quality when the ponds get drained. The settlement ponds allow most particles to settle to the bottom of the ponds, which are cleaned out with machinery when the pond is empty.

Animal welfare has never been an issue at the Chesapeake Fish Hatchery. With large quantities of fish in a confined area, disease is always a major concern. In the aquaculture business, the hatcheries take a different approach towards controlling disease by treating with salt rather than antibiotics. The theory behind using the salt as a treatment method is that the salt will irritate the fish's skin enough that the fish will produce an excess mucus that acts as a natural protection, and a living anti-pathogen device. The fish mucus covers the entire fish and if there is an injury that occurred on a fish, the mucus will prevent bacteria from reaching the area of injury allowing the wound to heal and regenerate. The mucus also contains antibodies that kill organisms on the surface of the skin. Thus, the reason behind the Chesapeake Hatchery using salt dissolved in the water to promote mucus production. When looking at salt as a treatment method from a broader perspective, there are similarities between salt water treatments for fish and for crops. As discussed at the Pioneer Plant in York, Nebraska, a Defol treatment was sprayed on the seed corn in August during seed development. As the cobs and kernels are developing, the salt water application would burn the foliage on the corn and the crop would push out larger kernel size. Both treatments of salt water give a benefit to the crop whether it is fish or corn. The benefit of applying salt to the fish ponds is that it saves money, time and resources by not having to select and catch the injured or sick fish and individually needle them.

So far, we have recounted how the fish are cared for, but we should ask ourselves what is done with all the fish that are produced. Most of the fish are produced to stock public ponds and waterways for recreational fishing. However, a small portion of fish, specifically grass carp are produced to control noxious aquatic weeds such as hydrilla. Hydrilla is native to the Indian Subcontinent and has found its way into American bodies of water where it is causing havoc on freshwater ecosystems. Hydrilla is choking out native aquatic plants which in turn, negatively affects local wildlife. Additionally, hydrilla can clog infrastructure such as water intake systems at hydropower generation stations which interferes with the efficiency of the system thereby increasing operational costs. Hydrilla found its way into American water ecosystems from inappropriate handling of the plant. Hydrilla is a popular plant in aquatic gardens; when people wanted to discard of their gardens they would simply dump their gardens into waterways, thereby introducing the noxious weed into local waterways. Even if the plant was broken up before disposal it is still able survive and spread because it has a tuberous root system. Moreover, birds can also spread the weed from one waterway to another.

Conservationists in Missouri have turned to grass carp, which is a species of Asian carp, to help control hydrilla. Grass carp is a natural consumer of hydrilla, as such conservationists have been stocking local water systems with carp to suppress the spread of the weed. This has created a need for the Chesapeake Hatchery to produce grass carp. This is the only species of fish the hatchery produces that are on occasion stocked in private ponds if landowner is having trouble controlling hydrilla. All other fish hatched at Chesapeake are stocked in public waters. Using grass carp as a biological control works well, however there is a concern that the grass carp could mate with the invasive species of Asian carp increasing that problem in American waterways. As a prevention measure to stop this from occurring, the grass carp eggs are put under hydrostatic pressure which turns the fish into triploids, thereby rendering them infertile. This is a great example of making use of natural ecosystems relationships as a means of biological control.

Our visit to the Chesapeake Fish Hatchery was very informative. We knew very little about fish production when we arrived for the tour, but we left with a lot of knowledge thanks to our knowledgeable and enthusiastic tour guide, Allison. She answered our many questions about fish production and left us excited for our next stop at the Otter Slough Conservation Area.  

Otter Slough, Missouri Conservation Authority Poplar Bluff, Missouri

While at the conservation authority they gave us a quick rundown of the levels of 'risk' a species can be ranked as. There are two classifications of risk: ‘State at risk’ and ‘Federally at risk’. The title given to the species is determined by the geographic severity of a species at risk. If the species is at risk in only a certain state, the ‘at risk level’ is localized to that particular state. For a species to be placed on the state or federal ‘at risk list’, data and population surveying is required as evidence that the population is indeed at risk and needs protecting. Only when a species is placed on one of these two lists are restrictions for that species protection set in place in that jurisdiction. The process of placing a species onto an ‘at risk list’ can be a difficult process; however, if there is public support for the initiative this can make it easier to designate protection for that species.

Alligator gar is one species of fish conservation officers hope to get onto the State species at risk list. Alligator gar are notoriously difficult to catch, in turn making them almost impossible to track and tag to get the data they need to place alligator gar on the list of endangered species. Salvador Mondragon, one of the conservation officers thought drones could be implemented in trying to track alligator gar to better understand their spawning habits and to help count the population.  
Missouri Conservation Department sign
When it comes to the goals of the Otter Slough Conservation authority they say they do not have any particular goal other than “to provide the best habitat they can”. The reason why the conservation does not focus their attention on one goal is so they can diversify their efforts across multiple species and be flexible in their conservation efforts to what needs the most attention. At the Otter Slough Conservation authority, they see themselves as farmers. As Tim Whitehead put it “they are the farmers of wildlife”.  The Conservation authority is a farm in the sense that as they manage wildlife and the land like a farmer does. However, there was a big focus on providing habitat for waterfowl such as ducks for hunting. Unlike, conservation land in Canada, in Missouri hunting is allowed and a big driver of how the land is managed. Certain sections of land are always set aside as a refuge for migrating birds, while other sections of land were actively managed for hunting. Both areas were flooded seasonally to provide optimal habitat for birds and often crops such as corn were planted as a feed source.

Both of our stops for the day taught us a lot about conservation efforts in Missouri. Many of us on the trip have farm backgrounds so how conservation takes place, specifically in the U.S.A. was something we have never learned anything about. We all learned a lot and perhaps gained a better appreciation for conservation and the importance of wildlife.