EKF :: Ku’ula 10-12 Curriculum

Raising Fish
Ka‘iana Trask

Abstract

The purpose of our project is to maintain and raise the fish until they are mature and ready enough to be transferred safely into the bigger pond. While they are growing and being prepped to be transferred we are going to be doing some things to them.

After the fish enclosure is finished we will be starting the stocking of the pond, for this we will catch one half of the fish and the other will be provided by the DLNR. The fish that are provided by the DLNR will be tagged and this will give us a chance to tell the fish apart, once all the fish have been put into their enclosures we will start our experiments.

While the fish are living and growing in their new enclosures we will be keeping logs of the amount of size, weight, and difference between the two types of fish. We also will be logging down the different types of food that are being fed to them and the impact these foods have on the fish.

But the main reason of this project is to find a way to produce the healthiest fish that we can, so that we may better our aquaculture system.

We hope to achieve all of these goals at the end of the year, but mostly we hope to just finish our projects so that we can learn something that will help the pond in the future.

Background Report

In the past one hundred years aquaculture in Hawai‘i has been at an all time low, but now with the help of many people the aquaculture program is on the come back. Many groups around the state are working together to help bring back the old ways of raising fish.

Aquaculture is very different now, with the addition of man made structures that house fish outside of the water. With these new techniques it is possible to raise almost any type of fish anywhere. Scientists and regular people around the world have developed the best aquaculture techniques for their environments. With these new methods Aquaculture has become a huge part in the fish production industry.

For the past ten years, there has been a new type of Aquaculture evolving. This type of Aquaculture is using the space of the open ocean. Man made enclosures 40x25 feet are anchored 40 ft. below the ocean surface out of reach of boats and the activities that lie above. A vessel present at all times monitors these enclosures. The enclosures may house almost any saltwater fish except some pelagic species that people have not yet introduced into this new type of Aquaculture. Although this has become a very effective way of producing good yields very fast. There are many down sides to it. This system requires very high amounts of labor and very high amounts of money. The enclosures are frequently damaged and have to be repaired often. Despite all of the down sides to this method in some areas it has become the leading producer of fish.

In Canada there is a new type of Aquaculture that is very similar to Hawaii's Aquaculture, but instead of using the rocks like we use, their method is to use nets. The people have perfected this Salmon farming technique so well that it is at the point where their yields are three times more than the wild catch. A group of local scientist and fisherman got together to develop this technique of raising Salmon. They built square enclosures that float on the surface of the water with the long net anchored down with weights so that it forms a box like structure under the water. The fish are raised in stages, from the fry all the way up to the breeding stock, the farmers designate smaller areas for the fry and the breeding stock so that they can concentrate on the rest of the yield. There are very little things that have to be worked out with this Aquaculture method. The only things that they have to accommodate for is the weather otherwise this is the perfect program for what they are doing.

The outdoor aquaculture system is gaining popularity in Hawaii and almost everywhere else around the world. This type of aquaculture is a very good and inexpensive way to raise fish. With good care almost any type of fish can be raised with this method. Big, round structures of plywood with black tarp are fitted inside to form the fish enclosures. These enclosures are fitted with pump systems and flow vents for frequent water changing and to allow the fish to receive the oxygen needed to survive. This system works with either fresh or saltwater. In Hawaii, the DLNR has perfected this technique very well and are now raising mullet and successfully relocating them back to the ocean and other places to help bring back the number of mullets in those areas.

The fishpond was one of the earliest forms of aquaculture and is still being used today. This type of aquaculture is a very labor-intensive process, with the outer walls being built first and then the building of the sluice gate, which controls the flow of water and the amount of oxygen in the water. All types of reef fish may be raised in the fishpond, thereby making the fishpond a very good aquaculture system here in Hawaii.

The Hale ‘o Lono fishponds are brackish water fishponds. Brackish water fishponds grow better yields and bigger fish. The reason for this is that the Limu has more nutrients and is more abundant in brackish water ponds.

The mullet also grows better in the brackish water so it will be easier for us to grow them in the ponds of Hale o Lono. The one thing that we are going to have a hard time with is if the fish will be able to survive on the Limu that is already in the pond. We want the fish to be able to survive in the ponds without any help from us, but I think that we will have to gather Limu from the bigger ponds and feed them everyday or every other day. The other thing that we want to do is to feed half the fish Limu and the other half food pellets. By doing this we can see which food we should feed them in the future. By feeding these fish different foods we can see how much they grow and at the end, we can see if feeding the fish artificial food changes the way it tastes. One of our major problems has been how to separate the fish. We first thought to use a net and separate the fish, but the food would just float to the other side. Now we are going to separate the fish and feed them separately. When the tide gets to low we will let them back in the bigger pond. By separating them, we will be able to distinguish the differences between the fish from feeding them different foods and therefore giving us better methods for future growth.

Another thing that we had trouble with is to keep the fish in the ponds. No matter how many holes I patched after a certain amount of time the fish found ways to get out. We have caught fish and put them in the ponds, but they have only stayed there for a couple of days. If we don't find a way to fix this problem we will eventually have to break down the walls and rebuild them.

All these things happen for reasons. If we do accommodate for the things that have gone wrong, we will never find a good way to raise the fish. All the work we are doing and all the experiments that are being done are for a reason. The reason is to better ourselves and out methods of raising fish.

After this semester is over, we should be up to speed and have fish in the pond. There are minor adjustments that we have to make and then we will have everything in place, then we can leave the rest up to the fish. After this year is done we hope to have raised the fish to maturity and relocate them into the bigger pond. If the pond is not ready then we will release the fish in to the ocean. We also want to find the best way to grow fish at Hale ‘o Lono so that in the future, we or who ever else is going to grow fish will have everything down.

We will be close to that goal at the end of the year but I am not sure if we will have found a good way to raise fish. We will figure out the problems and continue working on the fishponds as we have been doing until we are happy with what we have done.

In the future after I graduate, I want to come back and see the end result of this project. I want to see what Hale ‘o Lono looks like after everything is finished. I want to see the fishponds up and running. I want the pond to be how it was before.

Out of all the research I have done in the past months, I have learned a lot about the many different aquaculture systems. The one thing that could be seen all over the world is how the people adapted to the environment and built aquaculture systems that suited themselves and their lives.

Interview I

Division of Aquatics

What is the purpose of this aquatic center?

The state built this place for the betterment of the Wailoa estuary mullet population. They also intended to develop ways to reach and help the outer estuaries of Hilo for the overall mullet population.

Could you explain the housing process that you have here?

Well all off our tanks are fed brackish water that we extract from the Wailoa River. The water is circulated through all tanks and then taken back to the river. When the fry first arrive in the enclosures they are stored separately from the other fish. As they grow they are separated according to size. We feed our fish trout food pellets; we ensure that they get the nutrients that they need to get a healthy start. Once the fish reach a certain size (four inches) we insert a small wire tag in to their snout that can easily be detected. After all the fish are tagged they are put into an enclosure to recover. Once the fish are ready to be transported into their new environment we take them and run a tag check and lode them into the truck. We take them to one of the seven locations that we release fish at and free them into the water so that they can repopulate and strengthen the mullet population.

Is mullet the only fish that is raised here?

No, we also raise moi. We just started to raise the moi here, the moi is a very easy fish to raise, and they grow very fast. The process with raising the moi is almost the same as the mullet accept for the tagging process. Once the fish reach their certain size (four inches) they are fitted with a visual tag. We do this so that the fisherman can see if the fish had come from this station and so that they could supply us with valuable information.

What effects does this have on the population?

We effect the Mullet population by twenty percent. Every year we release anywhere from 20,000 to 30,000 Mullet.

Where do you get the fry?

In the beginning they were flown in by our sister station in Honolulu. But, we are the first to develop the brackish water spawning of Mullet. See the water salinity has to be at least 20 to 30 parts per thousand for the Mullet to spawn. If the water is any less the eggs will not float. The only way we can do this is when the tide is really high we place our poles right above the silt level. We do this so that we can suck up the all the salt water that we can, and store it all in the empty tanks. We later place one female and two males in one tank, we do not circulate the water because of the limited supply. The female releases about 50,000 eggs into the water, and then the males fertilize them. After the spawning is done the three fish are removed from the tank and the fertilized eggs start to grow. We leave the hatchlings in the salt water until they reach the stage (14 days) that they can be moved into the brackish water tanks. Every time we do this we do not use the same female, because we do not want the entire fish stock to have her genes. So the fish are rotated to ensure there are no gene glitches in the fish stock.

How many tagged fish do you get back every year, and what kind of information do you receive?

We get back about a 100 fish that have tags in them. The information that we receive is very vital to out system. By getting the information we can tell were the fish has traveled, from the original release site to where it was caught. We learn some of the migratory patterns of the Mullet, and it helps us determine where our future releases should be. By this we hope to establish a healthy population of mullet and reach all of our goals.

Interview 2

Could you explain your fish raising technique?

We started raising the fish from when they are an inch long. We separate them from the other larger fish and consolidate them in separate enclosures, depending on their size. The fish are kept separate and are separated by size. Once they get to be three or four inches long they are called finger lengths, and are kept in separate enclosures until they are ready to enter the main pond. Once they have reached the desired size for entering the pond, we move them in with the rest of the stock. It takes one and a half years for my fish to reach the ideal size for harvesting. See, because my water is so cold it takes almost twice as long for the fish to grow. In salt water you will have a very faster growth rate, and the fish will mature faster.

What kind of food should we feed our pua?

When you get your Pua it is important to know that they need to be fed a special diet. When they are young they need more protein to survive, they also need to be fed a lot more often. If you don't have any food it is all right to feed them Limu, but if you have the fish food they will grow a lot healthier and a lot faster. You can go to the store and by the trout fish food that is high in protein. When you get the food you should crush it up into a fine mixture and feed them at least three times a day.

What kind of enclosures should we use to raise our fish?

The best thing to do is to put them into an enclosure that will not harm the fish. Metal fencing and mesh are okay to use, but the mosquito net is the best thing to use. The best way to go is to form a little square our of PVC pipes and to screw on the mosquito net, it is very easy to make and is very inexpensive. These enclosures will last long and will not need to be replaced quickly. The hard thing for you to do is to go out and maintain these enclosures. See for me I can go out and check them because I have these ramps, you do not have this luxury. That I think is your only problem otherwise you are set.

A Critique
By Ka‘iana Trask

The article “Offshore Aquaculture Project Yields a Traditional Hawaiian Delicacy” is an article about a relatively new kind of Aquaculture that is being done here in Hawai‘i. This type of Aquaculture is the latest in raising large amounts of fish very effectively and very quickly, for example some fish farmers have perfected there fish farming techniques so well that using this method the estimated time of harvest is only four months. They place their fish in an enclosure that is specially made to be anchored 40 feet under the surface and attached to buoys so that it may drift freely in the current. A vessel that is always present closely monitors this enclosure, this vessel constantly maintains the enclosures and the fish that are in it, divers are sent down every day to make repairs and feed the fish.

All though this new type of project may sound like the way of raising fish in the future there are as many things bad about it as they are good. For instance when bad weather strikes these enclosures are blown and tossed miles a way from their normal grounds and must be towed back to their original spots and repaired. There are certain types of fish that cannot be grown in these enclosures such as the pelagic fish that migrate around the world, these types of fish are not successful because the quality of the fish, the taste is not the same. They have not yet found the reason for this but it is a huge problem for the fact that the fish that the fishermen produce will always be in more of a demand then the fish that they produce. Another down side to this is that it is very expensive to manage, there is always a vessel on the spot that is constantly doing things that cost them money, and maintaining the enclosure is not a cheap and easy task.

This article is a very good article it speaks truly of the facts of this new type of Aquaculture system and does not lie, the information is very accurate and could have only come from some one who has experienced this project first hand or from some one who has researched it extremely well. For example there are several statements in this article that state the trial and error of the people who have managed this project and therefore could not be forged or made up.

The information given in this article has no use to me or to my project; the only thing that would benefit me is if I take this type of Aquaculture as a profession. The authenticity of this article is perfect and has no reason to be altered or changed; it speaks perfectly of all the main points and reasons of the article.

A Critique
By Ka‘iana

The article that I speak of in this paper is the “Review of Cage Culture Activity Indicates Continuing Interest”. Since we were having trouble keeping the fish in the pond I thought it would be helpful if we researched something that would be useful to us. This article states almost the entire history of cage culture in America. It also states the different experiments that have taken place with cage culture.

Cage culture is a type of Aquaculture that came about in the 1970's and has grown ever popular since. It is a very effective way of raising fish in small confined spaces. Another reason why it is so popular is that it is one of the most inexpensive aquaculture methods. The fish are housed in a wire net enclosure, the size pending on the type of fishes that are being raised. The enclosure floats on top of the water with buoys or other man made floatation devices while the wire enclosure hangs down providing a moderate home. These enclosures are anchored with rope so that they do not float away with the current.

This type of Aquaculture is often used in fish food experiments. The reason why is that the fish can be solely concentrated on one area and fed one food, there by producing the best results with no interference's. Using this method is also a better way to harvest your fish. There is less labor involved and it is quicker to harvest fish.

There are certain down falls to raising fish with this method. One of these is the fact that by confining the fish to such small enclosures they do not get all the nutrients that they need. Special food is needed for the fish; the food has to be more nutritious, and it costs more. But this is just a minor set back compared to this flaw. By keeping the fish enclosed in such a small area they are vulnerable to disease at certain stages of life. When the fish are first released into their new enclosures they are still too young to fight off all of the deadly diseases. And this also happens when they are at the last stages before harvest. The cage is so crowded and with out room that it is very easy for the fish to spread disease once it enters the area of the enclosure. When tampered with these enclosures are easily destroyed or damaged, they must be anchored in an area with limited visitation.

This is a well-written article it speaks truly of the “Cage Culture Aquaculture System”. It states the pros and cons of this system and gives a full look of how it came about. The information in this article is very reliable and a good source of information. It was researched well and could not be forged or duplicated. There are several trial and error experiments in this article and are actual results, therefore making in an authentic peace.

This article will certainly help us with our fish loss problems. By learning the proper way to build and use this method we may find the solution to our fish loss problems. If we decide to do this with our fishponds it will be easier to manage. By doing this we may conduct our experiments without having to tag, or get them mixed up with other groups. By using this we can properly experiment with the use of different foods. By keeping the fish isolated from other schools and other food we can determine what food is best for up coming yields. It will also be easier for us to keep people stealing our fish and giving us a better chance to succeed and reach our goals for the year.

This article is very good and has no reason to be altered. It stated well of this Aquaculture method and is a very reliable source of information and guide.

Procedures

We started out with the rebuilding of the fishpond. Then we worked it up to where it was capable of housing fish. Then we experimented with putting the fish in the pond. Our original plan was to grow the fish in the pond. We would separate them and feed them different types of food. Then we would be able to figure out which food was better for the fish. But, along the way we ran into some problems. The fish that we where putting into the pond was mysteriously disappearing. We patched holes and did every thing that we could but we could not figure a solution. We finally thought to put out fish in a cage and raise them from there.

We started constructing an enclosure that was 4/8. We fixed it with mesh fencing. After the construction was done we went down to look for the place to put it. After we got the cage secured we needed to start catching the Pua.

The fish would naturally swim into the pond and we would just close the mākāhā. So when we decided to put the fish into the cage we needed to go and catch the Pua. So every day that we went down to the fishpond we had to catch fish. After a couple of weeks we had caught enough fish to start putting them into the metal enclosure.

A couple of days a week we would come down and feed the fish, and maintain the cage. After the fish had been in the cage for a couple off weeks we started to take measure. Once a week or two weeks we would come down and take the measurements of the fish. We would take them out of the cage, clean the cage and then put them back in.

After we got everything settled it was a routine thing with feeding the fish and taking care of the enclosure. Making sure that he fish are in good condition and are OK.

Data

The first half of this year, we spent our time researching for our project and rebuilding the fishpond. We learned many things, but the things that taught us the most was doing the project itself. We learned through trial and error, what was proper and what was not. For instance, if we had known that the fish would just keep escaping we would have just used the cage. But these things we only could learn through doing the project.

When we finally got the cage built and situated in the water we started to collect our growth data. We took measurements two weeks after we got them in the cage, and twice more after that.

We first thought that we were going to separate the fish and feed them separately but we ran into some problems. Later we figured out that we were just going to feed the fish Limu and monitor their growth.

The graph attached to this paper has the growth rates and the sizes of the fish. We took the readings over a month and a half period. We monitored the growth rate over that time period. We found out that the fish grow very well on the Limu diet. The fish can survive in the cage with only the bare necessities. We can successfully raise the fish in the cage to a certain size were they can be released successfully into the bigger pond. When we do this it increases the chance of the fish reaching the desired size for harvest or reaching maturity. This is what we found out by doing all of our research and by analyzing our data.

Affect on other Projects

I think by doing this project we know that now, in our pond you can grow the Pua at a steady rate by just feeding them Limu. They will come out healthy and ready to relocate into the larger pond. But most of all we have learned that we can raise the Pua to a certain size easily. In the future this will be useful to the people who are running the pond. They will be able to use the smaller ponds to raise the fish to a certain size before relocating them into a larger pond. This will be very helpful because there will be smaller percentages of fish dying and higher percentages making it to the desired size of harvest. By doing that the pond can be at its highest and it will be one thing that we don't have to worry about. So all in all it will benefit the future or the fishpond in some way.

Continuation

Now after everything has been done, after we have learned the do's and don'ts of our project, we now know the best way that we should have done our project. We would now be able to do the project that we set out to do. I think if we started all over we would have a lot more fish and would eventually be able to stock one of the ponds. Now that we have worked everything out we would be able to provide a substantial amount of fish. And by us raising them to a certain size it would give the fish an advantage to live and to reach the desired size. The only thing that would hold us back is the people stealing from our enclosures. Which is one thing that we cannot account for. At the learning rate now, if we continued our project, we would be well a head. Every thing would be so much easier.

Conclusion

While doing this project this year we did not reach all the expectations that we had hoped to. We did reach our main goal. We set out to be able to raise the fish to a size where they could be released into the bigger pond and make that transformation comfortably.

We have reached that size and the fish could be put in there right now if they needed to be. We have run into a lot of problems as the year went on, but we found some little way to go around them.

We know now that you cannot trust the walls of the fishpond to hold your fish in, or the fact that it is a public place. All these things we did not know when we started our project. They were all things that were not accounted for. Now if we had to do it again it would be so much easier.

We did not get to try feeding the fish different foods because of the fact that the pond was leaking our fish out. If we could have fixed that problem I think that our fish feeding experiment would have been a success. But for the fact that we were restricted to a cage held us back from our plan. Now if we had to do our project again we would know exactly what to do.

Once we had got our fish into the cage and we gave them some time to grow we started to take measurements. Every two weeks for about a month and a half we went down and took the measurements and compared them to the measurements of the week before. We found that our fish were growing a substantial amount on the steady diet of Limu. The fish were actually growing at a very fast pace. They would grow at an average of about three-quarters of a centimeter every two weeks. Now we know that we can grow the fish easily in the ponds and the enclosures that we built. So it would give us, or whoever else an advantage when it comes time to stock the outer ponds. So it has been a benefit for us and for the future of the fishpond.