Building Various Pueruli Traps for use in Lobster 'grow-out' Aquaculture

[jamesmusslewhite]

   This is a spin-off thread from the 'Building a Small Lobster Hatchery here in the Philippines'  http://www.philippines-expats.com/topic/26117-building-a-small-lobster-hatchery-here-in-the-philippines/?tab=comments#comment-192173 . 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. 

 

[jamesmusslewhite]

   The frame is constructed of a medium size lightweight bamboo lengths, which is lashed together with nylon monofilament 1.90mm line which is 150lbs.test rated, the local hardware stores simply referrer to it as #150 nylon. The can be as large or small as you like, but the preference for this project is a base measurement of (2 meter x 2 meter). This will allow the base to have a sufficient width to withstand wave action of the sea, while still being small enough to be easily deployed or removed from the water by a fisherman working solo using a small wooden boat. These floating platforms will most likely be deployed well within 200 yards of the shoreline in a water depth of less than 9 meters.     

   The base of the platform consist of three layers of bamboo . This allows the base of the framework to have the necessary tensile strength needed to withstand constant wave action, and the stresses imposed by the weight and constant tugging and pulling of the mooring lines and the five lines of mesh bundles which will be tied to the bottom of the frame. The bottom of the base frame will also be used to hash the flotation (plastic Jerry cans) in place once the frame is completed.

   The roof of the platform is a pyramidal bamboo frame which is used to house a emitting light source and a foul weather shield. For my own purposes I will use a galvanized metal wash tub (inverted) with an additional sheet tin shroud added, with all the interior and exterior surfaces painted a reflective white using marine rated paint. For my light source I will use simple kerosene (hand-pump pressured) fuel lamps. These are extremely dependable and lightweight requiring only the occasional replacements of spent mantles. Kerosene pressure lamps can generate the bright light needed to attract swimming Pueruli towards the platform. The white painted inside of the metal frame helps to reflect the lamp light towards the water surface, but also serves two other functions. a) The (inverted) metal tub with the added metal shroud acts a a rain guard to prevent the rain from contacting the hot glass globe. b) Acts as a heat guard protecting the flammable bamboo framework as fuel lamps can get extremely hot during long usage. Most kerosene lamp have a minimum of 1 pint fuel reserve which is sufficient for 8-10 hours continuous operation. The illumination rate of an average single-wick lamp is approximately 784 lumens which is on par with a 60 Watt light bulb, and double-wick lamps can produce the light equivalent to that of a 100 Watt bulb. They also generate lots of heat, so properly venting that rising heat is important. Some may of course will want to use unleaded gasoline instead of kerosene, but there is an increased chance of a fireball if there is leaking of gasoline around seals especially during times of heavy waves action.

   I could always use rechargeable LED lamps, fuel generators or use fuel lamps which are converted to use vegetable oils, but for the legitimacy of test I must use the simple materials and methods which will most likely be used by the average poorer small scale fishermen. They would not be able to purchase more expensive lighting systems. Simplicity is the methodology upon I will be establishing my primary baseline of the study, so I will be be employing the K.I.S.S. philosophy and good ole jungle-engineering during this project.  

   The framework has been fabricated in a miniature straw model which shows that is is durable enough to withstand the multiple directional stresses the framework will experience when deployed. So I am confident that the design is sound. My drawings which I have posted in this post only show the primary placement of the main bamboo used in the framework of the base. These drawings do not include the  and do not show the braces do not show all the inner bracing and placement of cross-braces.

   This shows the placement of the plastic 'Jerry' cans which will be used for buoyancy. These will be lashed to the bottom of the bamboo frame. There are some additional bracing which must be added first to the framework which are not shown in these drawings. These will be discussed later in this thread.

   This shows a 2D view showing the light placement, bamboo frame and placement of the plastic 'Jerry' cans. These plastic cans are quite common here in the Philippines for shipping cooking oils, coconut wines, coconut vinegar an soy sauces. You can also easily find them being sold in local stores so they can be used to carry and store water and fuel. 

they are perfect for lashing the plastic 'Jerry' cans onto the bamboo framework. Of course one can substitute these plastic cans for blocks of Styrofoam or other types of jugs, containers or small barrels. As long as it floats it will work, but always be mindful to keep the bottom of the frame as clutter-free as possible. This is so it will be easy to employ and harvest the 'net bundles' and to insure that as much light as possible can be delivered to the water surface below the platform.     

 

[jamesmusslewhite]

   Well although I have not updated this thread in a while I was working on the project. I was primarily focused on the floating platform which is the subject of another form thread. And I building a small lobster hut close to this facility so my wife can raise lobster individuals of her own. We have two other lobster huts in the waters around Dinaget Island. Well the floating platform is completed enough that there are 180 Algal-juveniles in the net, and the Lobster Hut is finished and the wife has 50 algal-juveniles of her own in her net. So it has been a productive four months since I last spoke with readers on this thread. So let me get you up to speed.

  I believe I mentioned that I planned to try to get everything together so I could start trying to catch live Pueruli and Algal- juveniles. And I bet most reader just said, ''You want to catch what"? So let me show you what the heck I am talking about.

   These little delectable sea-bugs are Pueruli (plural term) the singular term is a Puerulus. There are four developmental stages for Pueruli but the first occurs out on the edge of the Continental shelf, they Instar (moult) and transition to a clear little critter called a post-phyllosoma Panktonic-puerulus (stage 1). This stage will have developed to a (stage 2) Clear-puerulus by the she reaches the coastal coral/grass zones, and will be the smallest size Puerulus you will live-capture. Then over the next 4-5 weeks she will transition through the (stage 3) H-puerulus and the (stage 4) Pigment-puerulus. This is when for the first time they look like little facsimiles of their parents and is the first many of the 22 species of Panulirus lobsters can be properly identified, others will still need to transition to Algal-juveniles before reliable identification is possible due to lack of distinguishable markings.

   Once (stage 4) Pigment-puerulus reaches their latent stage they face an Instar (moult) which naturally has a 40%-60% mortality. But those that survive this Instar (moult) will have transitioned to the Algal-juvenile developmental stage. Most of the seedstock sold to local lobster farmers for their 'grow-out nets are Pueruli because they see them as being cheaper to purchase. The price for a (stage 2) Clear-puerulus just three years ago was 90php but today ranges from 200php - 250php, and the price for a (stage 3) H-puerulus or (stage 4) Pigment-puerulus now sell for 250php - 350php each. And still 40%-60% of those will die, more if they are mishandled before being delivered to the lobster farmer. I have personally know buyers who lost more than 80% of their Pueruli within three weeks after they were delivered. 

   Once (stage4) Pigment-pueruli successfully moult to Algal-juveniles those prices double, because those within the industry know that more than 90% of Algal-juveniles will survive to reach the (500 gram) buyer's weight. Presently a the (500+ gram) buyer's price is 3,000php (per kilogram), and at the right time of the season the (1,000+ gram) buyer's price id 4,000php (per kilogram).

   If one specializes in the 'live-capture' of Pueruli and Algal-juveniles it can be quite profitable as a stand-alone venture. If in combination with the ability to also use 'grow-out' aquaculture to successfully raise the seedstock you caught to market weights you can generate exceptional profits. If you are in the right general locations.  

 

[jamesmusslewhite]

(left click images to enlarge)

 

 

 

Edited September 28, 2018 by jamesmusslewhite

[jamesmusslewhite]

    I built one complete floating 'light' trap frame and but it through a lot of stress testing and I am quite pleased with the results..

   I have three other frames constructed but have not lashed on the floats yet. This shows a top view as the units are lying on their side.

This shows bottom view of the three same units lying on their side.

and this photo shows the variety of dwarf bamboo used in the construction of these frames.  

 

[jamesmusslewhite]

   It took me a couple of months to find the species of bamboo I wanted to use to make the first four frames. This is a thick-walled dwarf bamboo species which will allow me to build a frame at a 3/4 scale.

   This will show a step by step walk-through of the construction of the frame of a Floating 'Light' Trap to be used to 'live-capture' lobster Pueruli.

   First cut the required bamboo lengths.

    Lay out the the first four lengths to form a square and lash together the corners.

   This photo shows the lashings.

   Then the five remaining bamboo lengths which will form the frame base are then placed and lashed together.

[jamesmusslewhite]

   The frame base needs length sections which will allow the plastic 5gal.''Jerry' cans to be sufficiently lashed to be bottom of the framework.

   This unit actually sits on 6 plastic cans (3 on the edge). Two shown in this photo are just being used while all the lashing are being completed.

   Photo of the lashings used.

 

[jamesmusslewhite]

This photo shows the complete frame with all the bracing.

   Moving the platform to the waters edge. As you can see the frame is light weight and very easy for two people to carry. 

   The unit was set in the water and it was sufficiently buoyant and stable

We still need to fabricate lightweight holding racks in the topsides of the outriggers. There will be four floating traps (two on each side) and transported to and from the locations were they will be deployed.

[Mike J]

Fascinating - thanks for sharing. 

[jamesmusslewhite]

   Well I finally finished the second video of the 3-part Youtube video series ‘Tropical Spiny Rock Lobster 101 - species Panulirus 'ornatus' - Video (2of3)’ which I started work on New Year’s day. It is almost an hour and forty-five minutes long so it is about twenty minutes longer than the first video of this series. The issue was a lack of posted photos on the internet which related on the subjects discussed, which required my digging through my own personal archive of photos and quite a bit of artwork needing to be created. But I am satisfied with the end results and it feels good to have this second video of the series finally uploaded. I have a few smaller video projects that I have had on hold, one is a couple of videos of the lobsters in the grow-out nets which follows what was done through a local disease outbreak; and the other project is a collaboration with a local Filipino lobster buyer/shipper/transporter who’s skills and technique is extremely successful, and we will video and discuss all the steps needed to properly prepare and ship lobster at distances in excess of 10 hours. Rio has shipped lobster as far as the Middle East with successes of 100% survival rates of delivered stock. He has decades if practice hands-on experiences in lobster aquaculture and is a walking ‘treasure trove’ of knowledge which he wants to share.      

  https://www.youtube.com/watch?v=D5Im52lkdwo