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Building Various Pueruli Traps for use in Lobster 'grow-out' Aquaculture
JamesMusslewhite posted a topic in Farming & Gardening
This is a spin-off thread from the 'Building a Small Lobster Hatchery here in the Philippines' https://www.livingincebuforums.com/topic/95658-building-a-small-lobster-hatchery-here-in-the-philippines/. I will be discussing several types of lobster Pueruli traps which are commonly used with success in pueruli collection in neighboring countries, but have yet to be widely used here in the Philippines. I have designed two variations which I am now ready to start making which I will use over on Dinagat Island. These two prototypes are a floating 'light' trap and a coconut log trap which will be durable, inexpensive to construct and easy to use and maintenance. These will be used to safely 'live capture' lobster Pueruli (plural)/Puerulus (singular) for research. I will be maintaining logs to document nightly catch numbers throughout the collection season, details as to preferred locations and water depths. The captured Pueruli will be quickly relocated to 'nursery grow-out' nets where they will be properly sized and monitors. This will allow be log weekly growth and weight rates, as well as weekly mortality rates. I imagine most readers of this thread do not know what a Pueruli or Puerulus are or what they even look like. This little sea bug is commonly referred to as a seedling, seed or fingerling in most text you will read, and it is the very heart of the lobster aquacultural industry. This is a Puerulus of the species Panulirus ornatus commonly referred to as the '''Ornate Rock Lobster' or 'Tiger Lobster' and is one of eight different species of Panulirus lobsters commonly found in these waters around the islands of the Philippines. It grows the fastest and the largest of any species of lobster in this region, and is most prized by the Asian markets (Singapore, S.Korea, Japan, Hong Kong and China). It yields 38% more usable meat per individual (per weight size) than do North American and European lobsters species, and the meat yielded has been proven to possess a creamer texture and sweeter tasting meat. Sorry Canada, Maine and Europe but the fact is that your clawed lobsters are actually considered as 2nd rate compared to these puppies. And here they swim to shore nine months out of the year (free from the sea) and to lobster aquaculture they are literally swimming gold. From this size small size a 'Tiger' lobster can, in less than 24 months, grow to over 1 kilo (1,000grams) and be worth over 2,800php per kilo (1,000gram) when sold to the lobster buyers. This is the floating 'light' trap which I designed, and I will first build five units which will be deployed in a small fishing village where I have a small beach front lot facing the Philippine Sea and the Pacific Ocean. We are within walking distance to town of Cagdianao which is a know hot-spot for lobster, but the fishermen have yet learned of these two methods which I will be employing. If proven successful this will allow far more locals to generate a viable revenue stream, while helping to also provide easier access and more abundance to healthy seedlings for the lobster growers. The platform is constructed of bamboo and deployed generally in areas at a water depth of less than 9 meters. Nylon cord is tied to the bottom of the frame and suspend bundles of netting (1 meter apart) down to the seafloor. The platforms I will be building will each suspend five lines of net bundles. These are deployed during the 'New Moon' cycles when the Pueruli are swimming to shore under the cover of darkness. You can see by the drawing that suspended in the center of the frame is a lamp. This lamp can be fuel, battery or electric and is centered over the floating platform to help attract the incoming swimming Pueruli to the suspended bundle traps. Researchers have learned that the primary settlement of Pueruli are within 2 meters of the surface and 2 meters of the sea floor. The Pueruli are naturally drawn to the light source similar to that of a common moth. The light attracts the Pueruli directly under the platform where the suspended mesh bundles then entice them to settle within the bundled netting. These are harvested around midnight and at sunrise. The traps are deployed before dusk and collected after dawn when they are harvested. One advantage with these units is once they are deployed the fishermen can continue fishing and only has to attend to the unit to replenish fuel for the lamps or late-night harvesting. The drawing of mine bellow shows the second prototype that I will be building over the next few weeks, which is a Vietnam style 'Coconut Log' Puerulus Trap. I will be building 5 units for my own research and will be deploying them in the same location were I will be using the floating 'light' traps. This year I will use the five 'floating light traps' and the five 'coconut log traps' mainly to locate the best locations and water depths to use them. Then next year I will deploy 10 units each in a study I will be conducting where I can monitor the complete season. I intend to monitor three seasons and then compile the data, then I can share this data with the various fisheries departments. These units will be durable, inexpensive and easy to make and are permanently anchored to the sea floor during the whole of the collection season (9 months). These placed in locations with a minimum water depth of 2 meters, and are harvested each morning during the collection season. The floating 'light'' traps are more complex to deploy and use which restricts their usage for many poorer fishermen, but the 'coconut log traps are extremely low cost and being permanently located in the shallows allows poorer fishermen to build and maintain them. I have yet found any credible documentation showing the average yearly collection numbers capable of either trap type. What I have found says they were successful at collecting Pueruli, but not documented yearly results. My curiosity drives me to find out for myself, because if both types prove to be productive it could be a huge benefit to rural fishing communities. This photo shows a Vietnam style 'Coconut Log' trap in usage, and actually shows several Puerulus who have settled in the shallow holes. You can see that they back into the hole and use their antenna to monitor the conditions outside of their newly settled habitats. If you look closely at the lower photo you can see their antenna protruding from the holes. Just those three Puerulus could easily net that fisherman 600php, and if he has 4 traps or more which each had 3 tenets to collect that fisherman would have net 2,400php that morning. One could then see such a simple thing could have on a poor fisherman and his family as well as the community. Many expats have family who are dependent on the sea and such a venture would require very little venture capital for a start-up. The in the study I will be starting next year I will also be using several other Pueruli trap types and methods, but I feel these two mentioned above may be the most promising. That is why I wanted to build these 10 units so I could play around with them this year so I could perhaps learn where best to deploy them before I begin the study. Once I have these completed and in operation I will then see about perhaps building prototypes of the others. I still have to finish the floating 'net' platform and I have a small pier to build as well as a floating PVC net system for use in the saltwater facility behind the hatchery facility. I will see what time allows me in the future.- 12 replies
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It looks as though I have been enlisted to design, help fabricate, and install a filter for a medium sized koi pond with fountain for a local church. It consists of a 16 foot diameter lower basin that hold 3000 gallons or so that has a 6' basin above it. It also has a large statue on top of the upper basin with a water feature. It is rather impressive and was fabricated and shipped here from China. They already have a decent sized pump hooked up to it to circulate water and run the fountain part of it, but they have no filter. The koi in it don't seem to mind and are doing extremely well, but they are difficult to see except at feeding time. That will soon change. If money was no object and a large pressurized sand filter or media filter was easy to procure here I would go that route, but their budget along with water and electricity concerns have caused me to formulate a better route which is as follows: The upper basin, which holds approximately 400 gallons will be used to house media for beneficial bacteria. This media will consist of medium (2-3mm) sand which will have the return water from the filter pumped up through the bottom of the sand. This will greatly increase the surface area for beneficial bacteria (BB). The upper basin will need to be drained so the water lines that feed it can be reworked so that water will enter the basin from its bottom instead of approximately mid-way up. The lower basin will also get some plumbing rework done to it to as the drain needs to be modified as well as a secondary water return from the pump. The whole thing was obviously designed as a water feature without much thought for fish. The bottom of the lower basin is flat. In a perfect world it would be sloped towards the drain. This would greatly effect the way water circulates and how waste makes its way to the pickup (drain) for the pump. I have suggested that the pond be drained and the koi moved, so that the bottom of the lower basin can have a sloped concrete layer installed, but they are not enthusiastic about this at all and it will likely not happen. The filter will consist of three, possibly 4, 55 gallon plastic drums. Drums #1 & 2 will both have vortex filters. These are simple and inexpensive to construct and do a fantastic job of removing solid waste and clarifying the water. They are also extremely simple to maintain as there will be a bottom drain with a valve attached. With weekly partial draining of drums #1 and 2 the majority of the solid waste will be disposed of. Since they adjoin the river it would be a simple matter for this to drain into the river, but I am trying to get them to use the waste to fertilize and water their extensive selection of plants. DIY Vortex (aka swirl) Filter https://www.youtube.com/watch?v=-mLPro9N7FQ (youtube.com/watch?v=-mLPro9N7FQ) More detailed info about it is here: http://www.earthangroup.com.au/building-simple-swirl-filter/ After drums 1 and 2 the water will go to drum #3 for polishing and biological filtration. DIY Sand Filter (youtube.com/watch?v=QQUtBrEcaB4) After this step the water should be polished to a fine degree, but we will see. If I am not completely happy with the result I will add drum #4 for final polishing before the water goes back to the pond. Water changes should be minimized because the lower basin will be partially stocked with aquatic plants such as water hyacinths. I want to corral these so they are partially under the overhang of the upper basin. Hyacinths work extremely well at reducing and eliminating nitrates from fish waste. With nitrates removed/reduced algae and green water is eliminated for the most part. Since the price of city water is ridiculous here in Dumaguete (90 centavos/gallon!) it is cost prohibitive to do large water changes so we will also be constructing a very large water catch system. The church has a number of buildings and has a massive roof area. Some of the roof area is fully guttered (about 1/2) while other sections are not. Even with just 1/2 the roof guttered I think we will be able to catch enough water during the rainy season to keep this, and 3 other ponds full. Right now all of the rain water goes on the ground, which all parties agree is a waste. Here in Dumaguete rainwater is acidic because of air pollution. To "sweeten" the water and raise the pH we will be using crushed coral placed in mesh bags. I have a pH as well as other water test kits so it will be a simple matter to see if the coral is enough to do the job or if another step will be needed such as adding baking soda which is a completely fish safe alternative to raise water pH. When all is said and done I hope to have pictures that show the results. I will have to rely on the church though as my Nikon has lense issues and needs to be repaired. Most of the stuff that will be needed to do all of this will be donated, but I hope to compile an accurate list of what was used and the quantities involved so I can come up with an approximate cost if others want to do something similar. They are in the process of acquiring my "want list" now. I told them it would be nice if we could get it all done before the rainy season really kicks in here which historically starts in June, but time will tell if that happens. Stay tuned.......
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