Developing sustainable aquaculture methods for the mummichog, Fundulus heteroclitus, with emphasis on egg production

Developing sustainable aquaculture methods for the mummichog, Fundulus heteroclitus, with emphasis on egg production

Summary

The mummichog, Fundulus heteroclitus, is the most common salt marsh fish along the Atlantic coast of North America. As such, it serves as an essential vector of primary productivity to higher trophic levels. This fish is also a popular marine baitfish throughout this range. However, supply is seasonally limited since the product is wild caught, though anglers would prefer to use this bait year-round. A multi-season demand, in combination with extreme tolerance to a variety of environmental conditions, makes the mummichog an ideal candidate for aquaculture production. Aquaculture is regarded as a sustainable alternative to wild catch fisheries. Development of aquaculture methods for the mummichog can provide economic benefit to farmers, distributors, and bait retailers while alleviating pressures caused by the wild fishery to the fragile estuarine habitats this species is found in.

The overarching goal of this project was to develop aquaculture methods for the mummichog which increase yield and efficiency for a sustainable business model. I addressed this need by examining egg collection techniques from both a methodology and cost-of-labor standpoint. I assessed the effect of egg collector depth on egg production and viability and egg collecting intervals to determine a sustainable labor-cost to yield ratio. By combining my objectives into one multifactorial experiment I was able to address both of these questions at once. I found that in the absence of tides mummichogs still prefer to deposit their eggs in shallow water. Also, more frequent collections do not increase yield. Results of this project indicate that mummichog growers should place their egg collectors 8 cm below the surface to harvest the most eggs, and maximize labor costs by collecting eggs twice per week.

Objectives/Performance Targets

Objective 1: Explore the effect of egg collector depth on egg production and viability. I have conducted and completed an experiment that examined the effect of egg collector depth on these dependent variables.

Objective 2: Explore egg collecting intervals to determine a sustainable labor cost-to-yield ratio. I have conducted and completed an experiment that examined the effect of egg collection frequency on this dependent variable.

Accomplishments/Milestones

March – I ended up having an unexpected cost savings on one of the lab supplies, the refrigerated incubator. After contacting my SARE representative and receiving permission, I was able to reallocate these cost savings into labor. This allowed me to hire two student research assistants instead of one.

April – Once the students were hired I finished ordering all of the preliminary supplies for the project and we began constructing egg collectors. I used the disc-style egg collectors that I developed rather than the tray-style collectors that I initially indicated in my proposal. My research prior to this project indicated that the disc-style is the more efficient egg collector for collecting eggs that hatch into viable fry. One drawback of the disc collector is the amount of construction time necessary to drill discs and assemble spindles, so the additional labor was extremely useful for accomplishing this task and starting the experiment on time. As orders were coming in, I obtained local mummichogs from a bait fisherman to use as broodstock for this project.

May and June – As soon as the fish began spawning, we began the experiment and executed it to completion without any major mishaps. I was able to shorten the amount of time needed for the experiment phase of the project by addressing both of my objectives in one multifactorial approach instead of two consecutive experiments, thus completing the experiment within eight weeks. At the end of May I hosted a hands-on hatchery methods workshop and published a mummichog hatchery methods fact sheet with DSU Cooperative Extension.

July and August – I was able to obtain a count of all the eggs prior to incubation by taking photos of back-lit eggs in gridded dishes. This additional step allowed me to analyze precise counts of eggs directly from the collector rather than relying on post-incubation numbers which may not be as accurate due to handling and degradation. Experiment was completed. All data were successfully entered and error checked and I am now analyzing data and summarizing my results.

October – I gave a presentation on hatchery methods for mummichogs, including aspects of this project, at the Atlantic Estuarine Research Society meeting.

December – I presented results of this project at the Northeast Aquaculture Conference and Exposition.

Ongoing – This project is a component of my master’s thesis. As such, I am including this experiment as a chapter in my thesis. I am on schedule to defend my thesis and graduate in May 2013.

Impacts and Contributions/Outcomes

Workshop – I planned, advertised, and hosted a hatchery methods workshop at the Delaware State University Research and Demonstration Facility. Our facility is central within the state of Delaware but remote to other locations, yet this workshop drew participants from Washington, D. C., Virginia, Maryland, Pennsylvania, and New Jersey. I was able to directly show the participants all of the aspects of growing this species that are currently known. Most of these culture techniques have been developed directly at our facility which operates on a small-scale production setting so the numbers and stocking densities we were discussing are directly applicable to start-ups and large-scale farms alike. Participants walked away with the knowledge of how to successfully spawn, collect eggs, and care for newly hatched fry. I also emphasized that growing these fish has enormous sustainability potential; they are omnivorous and can survive on diets with less fishmeal, farming them is more reliable and environmentally friendly than collecting them from the wild, and using methods I have developed will ensure maximum production with minimal labor. A few of the participants have actually tried growing this fish at their facility, but with little luck. They were able to learn from this project how to maximize egg collection to make their venture more successful. I donated spare parts from collectors so they could take them back and use them as a prototype to build their own. This interaction has the potential to have long-term benefits for those fish farmers.

Fact sheet – To go along with the workshop, I created a factsheet that describes indoor hatchery techniques for the mummichog. The factsheet was published/hosted by DSU Cooperative Extension and is in a second revision which will include the results of these experiments. I have been contacted by potential growers around the Mid-Atlantic through these factsheets that are hosted on the DSU web site and they serve as a valuable tool for those farmers looking to branch out to this newly cultured species.

Egg and fry donations – An unexpected outcome emerged from the need to deal with the abundance of fry and eggs produced by this project. Eggs collected during this trial were donated to research projects, a local high school, and a local farmer. Undergraduate researchers continue to examine alternative culture methods for fry. In addition to donating eggs and fry to the local high school, I have fostered a relationship with their animal science teacher and class. The teacher is the Future Farmers of America coordinator for the school and is also working on her master’s degree and looking to develop curricula using these fish in the classroom. For her class I have given a lecture on my research, how to raise mummichogs, and why we should farm them instead of fish for them. I have also given the students hands-on training in egg collection and they have constructed egg collectors for use in their system. Using the methods I have developed through my research and this project, they will begin collecting eggs once the fish have grown to reproductive size. Likewise, the local farmer has since moved the fry into a farm pond and looks to spawn the adults beginning next spring. These donations were an unanticipated outreach component which have literally put these fish into the hands of farmers and future farmers.

Student research assistant – One of the student research assistants that worked on this project was an education major. After working on the project, gaining valuable STEM experience to share with her future students, and meeting local agriculture teachers, she changed her major to science education. She is now pursuing a career as an agriculture/animal science teacher at a technical high school. This experience has influenced a future teacher to share her gained knowledge and teach future farmers.

Conferences/ networking – I have shared the results from this project at two different conferences. In the Mid-Atlantic I gave a talk at the fall Atlantic Estuarine Research Society meeting entitled, Evaluation of mummichog egg deposition in a large-scale laboratory setting: farming instead of fishing? This meeting proved to be an important networking opportunity for me to meet with stakeholders from the Mid-Atlantic and I gained valuable feedback about potential growers and distributors. At the biennial Northeast Aquaculture Conference and Exposition I gave a talk entitled, Developing sustainable egg collection methods for the mummichog: Frequency of collection and collector depth. This opportunity allowed me to share this research with northeast researchers, extension staff, and potential growers directly.

Results from the experiment – I determined that mummichog egg collectors should be placed shallow in the water (8 cm) to optimize egg collection (Figure 1). Collecting eggs should only be done twice per week to maximize yield to labor costs (Figure 2, 3). These results build on additional research I have conducted towards developing sustainable aquaculture methods for this species. Growers should adopt these methods to increase yield and minimize labor costs.

• Figure 3 – Calculated effort of different collection regimes
• Figure 1 – Egg yield of different collector depths
• Figure 2 – Fry yield of different collection regimes

Collaborators: