THE FLOATING NET - BAG TECHNIQUE
INTRODUCTION
The current farming technology of Eucheuma is by hanging the propagules along nylon monolines of various lengths or other types of ropes. The lines may be installed off-bottom or floating both of which require tying the propagules to the lines. The off-bottom technique requires lines, plastic straws, and stakes while the floating technique uses bamboo raft or long lines with floats spaced along the line. Sometimes, a series of long lines are attached to wood or bamboo poles to keep them parallel as well as to prevent entanglement of the lines. The length of the lines varies from 10–50 meters. The lines used in the off-bottom technique are set about 30 cm above the ground while those in the floating technique are set about 30 cm below the surface of the water.
Various problems are associated with the hanging method of farming Eucheuma. Some of these problems are the following:
1. Tying of the propagules.
Every propagule ( vegetative cutting weighing about 50–100 g) is tied to the line by means of plastic straw or evelon string. This process is labor-intensive and constitutes the most expensive and time-consuming aspect of farming the Eucheuma. To the farm manager, tying the propagules is a production bottleneck which can be solved only by hiring a lot of workers (15–20 per hectare) every day just to do the tying operations. If cheap labor is available, employing a lot of tiers may not be a major problem. However, in cases where the farm site is situated in a remote area, the workers are not available unless they are brought to the site and provided with housing facilities. This is a major management problem. Tying the propagules also produces a processing problem among the Eucheuma processors especially family-farm-produced seaweeds. The plastic straws and sometimes pieces of strings used in tying the propagules are not removed by the farmers during the harvesting and drying process. Hence, the additional task of removing the plastics which constitutes an added expense, is borne by the processors.
2. Propagule losses.
Loss of propagules during the growing period is a major reason for low productivity in seaweed farms. Losses are due to various factors such as loose tying, breakage of the branches due to strong waves or bites by the grazers which create a point of breakage. About 30–50% of the probable yield of Eucheuma is lost between 30–45 days after planting due to grazer bites or simply overweight of the branches. The propagule losses are much higher during a typhoon. Typhoon-generated waves not only break the branches but also uproot the stakes hence, the lines together with all the propagules tied to it are lost.
3. Grazer damage.
In the line method of planting Eucheuma, the propagules are open to the attack by grazers such as siganids, sea urchins, and synapta (bahag-bahag). The damage can range from 0–100% hence, is considered to be a major problem especially in starting a Eucheuma farm in a new site. Grazers such as siganids are seasonal problems in some areas (generally serious during the spawning period from January to June) but are continuous problems in other areas. Siganids are hard to control especially when they are young. They eat the growing points as well as peel off the tender skins of the plants so that the attacked plants grow slowly and eventually die due to malnutrition and infection by bacterial and fungal diseases. The sea urchin and synapta fix their mouth on the thallus of the Eucheuma until the branch breaks. Broken branches are carried by the water current and deposited to the deep channel of the sea where they are difficult to recover.
4. Competition.
Other seaweeds such as green and brown algae cling to the propagules as well as to the lines. These algae compete for nutrients and light. The Eucheuma propagules when covered by other algae grow slow or eventually show symptoms of sickness known as ice-ice. Drifting seaweed such as sargassum, turbinaria, hydroclathrus, ulva, and hyphnea are caught by the propagules and lines. When they are already heavy, they will cause the propagules to break. These drifting algae are still alive hence, they also compete for nutrient and light. It is important to remove these competitors but removing them requires extreme care otherwise a lot of propagules or their branches will be lost due to breakage.
THE IDEAL FARMING TECHNOLOGY
The ideal Eucheuma farming technology should be one which can ensure high productivity and high profitability both for the farmers as well as for the processors. High productivity and profitability can be achieved through prevention of propagule losses, promoting fast plant growth, and growing the plants year-round. This objective can be achieved by developing a technology which allows the following advantages:
The propagules are protected from photo-oxidation which usually occurs during summer months. The net-bags provide partial shade to the propagules as well as prevent rapid build up of high water temperature.
THE NET - BAG TECHNIQUE
1. Fabricating the bag.
The grow-out unit used in the Net-bag technique is a bag fabricated from nylon double knot net described as: Twine-0.40 mm; mesh - 10 K; depth-50 MD; length-1000 meters.
The fish net has a mesh size of about 1/4 inch . The fish net is cut to a length of 80 cm. The dimension of the net after cutting is about 90 × 80 cm . Fold the net along the 90-cm side and then sew together the side and the bottom. The dimension of the net bag after sewing is about 80 cm. long and a diameter of about 45 cm. The bottom side should be bundled and tied with a 3mm polyethylene rope. The top portion of the bag should be prepared so that it can be opened or closed easily like a “zipper” to facilitate loading and unloading of the propagules.
2. Preparation of the propagules line
The propagule line is a 5-meter line. The net-bags are attached to this line at a distance of 50 cm. between net-bags hence, a total of 10 net-bags are attached to this line. A 25-cm loop is provided every 50 cm which makes it possible to easily attach and detach the net-bags to and from the propagule line.
3. Loading the propagules and float in the net-bag.
Select the healthy-looking plants to be used for propagule or replanting purposes. Weigh one (1) kg of the selected plants and then put them into the net bags . The loading of the propagules to the net-bags is usually done after the 10 net-bags have already been attached to the propagule line. After a lot of practice, it is no longer necessary to weigh the propagules because this can be done by using a small bucket which contain about one kg of the propagules. Put 1 or 2 pieces of styropor floats into each net-bag before closing the mouth of the bag. Then bundle carefully the 10 bags so that it is convenient to transfer them to the field to be attached to the anchor lines. The float should be about four (4) cm. square which is strong enough to keep the net-bag afloat. The propagules which float and sway with the waves are usually clean. They grow fast due to the beneficial effects of “self-cleaning” and sunlight which enhances photosynthetic process.
4. Laying out the anchors lines
Layout the farm by planting stakes on the four corners of a square farm (100 meters long and 125 meters wide). The anchor lines should be laid out parallel to each other at a distance of five ( 5) meters. The anchor lines should be made of strong materials such as rubber strips or big ropes. The two ends of the anchor lines should be moored to a very strong anchor such as cement blocks or iron anchors. Sand bags should also be tied along the anchor lines at distances of 5 meters so that the stakes will not be pulled out by strong currents or waves. Knots are placed along the anchor lines at distances of one (1) meter so that the distance of planting is equivalent to 0.5 × 1.0 meter. Navigational alleys ( 5 meters wide) are laid out every 25 meters (please see field layout for a one hectare Eucheuma farm in Annex 3). The one hectare farm consists of 20,000 net-bags or 20,000 kg of seedlings.
5. Tying the Propagule lines to the Anchor lines
The ends of each propagule line are attached to the anchor lines perpendicularly at a distance of one meter. There are 100 propagule lines installed along the 5 × 100 meter strip. There are 2,000 propagule lines per hectare if alleys or pathways are not provided within the one-hectare farm.
6. Maintenance.
The net-bag technique of planting Eucheuma requires maintenance just like other techniques. However, the effort involved in maintenance operation is much less compared to the monoline system for the following reasons:
In farm sites where the water is clear and the water motion is good, the net-bags are generally clean and do not need to be cleaned frequently. However, it still pays to give them FTLC.
7. Harvesting.
In the monoline system of planting Eucheuma, a lot of plants are lost during harvesting. In the net-bag system of farming, few plants are lost since the plants are inside the bags. Harvesting is done by detaching the propagule lines and then dumping them into the boat. Since the bags are floating, they can also be tied together and pulled toward the seashore without any fear of losing the plants due to breakage of the whole or portion of the propagules. In other words, harvesting is a lot quicker in the net-bag system compared to the monoline system. An alternative method of harvesting can be done by opening the net bags in situ and removing about half of the content of the net-bags which represents the growth increment. In this way, planting and harvesting is a simultaneous process which saves time and effort.
8. Drying.
The net-bag system is interesting because the grow-out unit can also be used as a drying unit by just hanging the five-meter line (propagule holders with 10 attached net-bags containing the harvest) over a horizontal pole for 1–2 days to produce a semi-dry product. This will reduce the requirement for a flat drying space by about 50%. Drying studies showed that Eucheuma dried inside the bags by hanging (exposed to the wind) do not lose their quality even if it takes more than one week to dry. For quick drying, remove the seaweeds from the bags and then put them over a sundrying platform. The platform should be about one meter wide and of any desired length and about one meter high (waist high). The floor of the drying platform should be slatted. Split bamboos or coconut petioles can be used for the flooring. It is a good practice to put a fish net over the slatted floor to prevent losses of small-sized seaweeds. It is necessary to dry the seaweeds thoroughly (2–3 days) which means that the product should have a moisture content of 30–35%. The seaweeds are well-dried when the salt crystals show on the surfaces of their surface and when the seaweeds are not slimy anymore.
10. Sorting.
Eucheuma harvests produced using the monoline technique usually require sorting operation which is the separation of plastics, leaves, dirt, and sand from the seaweeds. Net-bag-produced-seaweeds are not tied with plastic straws hence, they do not carry plastics with them during the drying process. If they are dried initially by hanging, they do not attract dirt, sand, and leaves. This problem is usually associated with wet harvests which are dried on the ground or slabs.
ECONOMIC CONSIDERATION
a. Cost of materials
Some people believe that the net-bag technique is expensive compared to the monoline technique. This is not true . A net-bag which can carry an initial weight of about one (1) kg of spinosum or cottonii costs about PhP4.50 (materials and fabrication included). A one-kg propagule when planted using the monoline technique requires a 5-meter line which costs about PhPO.70 per meter or PhP3.50 per line. The plastic straws used for tying the propagules cost about PhPl.00 per line. These plastic straws have to be replaced every planting cycle. The tying operation costs PhPO.50 per line . Therefore the total cost of materials for the monoline system is PhP5.00 per line. Also consider the production uncertainty of the monoline system . It is true that the plants grow much faster in the monoline system but in areas where waves are damaging, grazers are devastating, and green algae are blooming, there is no way that the monoline system will work. In the net-bag system, about 5 farmers are needed to farm 1 hectare while about 20 farmers are needed when the monoline system is used. The productivity per farmer is much higher in the net-bag system compared to the monoline system especially in areas which are affected by typhoons and where grazers are abundant throughout the year. In these areas, the monoline system of planting is not recommended.
b. Yield
Assuming an initial propagule density of 20 metric tons per hectare and a harvest/propagule ratio of 3,0(Gp=3.0%) at one month after planting, the expected harvest is 60 mt. After removing 20 mt for replanting purposes, the net harvest will be 40 mt which when dried will produce about 5.0 mt of raw seaweed with a moisture content of about 30%.
c. Cost of Production
| Philippines Pesos (PhP) | |||
| Materials (per hectare): | |||
| 1. Net bags and floats, 20,000 pcs at PhP4.20/pc. | 84,000 | ||
| 2. Anchors:25 at PhP70.00 | 1,750 | ||
| 400 sand bags at PhP2.50/bag | 1,000 | ||
| 3. Monofilament lines (200# test), 6000 meters, at PhP0.70/M | 4,200 | ||
| TOTAL | 90,950 | (US$3,498) | |
| Average material cost per month=PhP90,950/24=PhP3,789(US$145) | |||
| Labor : | 1. Putting sand in bags at PhP1.50/bag | 600 | |
| 2. Planting, maintenance, and harvesting | 15,000 | ||
| Total Cost of Production per Hectare/Month | 19,389 | ||
(Includes average monthly amortization cost of the materials) | |||
| Estimated Gross Sales of Seaweeds | Philippines Pesos (PhP) | ||
5,000 kg at PhPl0.00/kg | 50,000 | ||
| Gross Profit (PhP50,000-PhP19,389) | 30,611 | ||
| Cost of Production/kg of Wet Harvest = PhP19,389/40,000 kg = P 0.49 | |||
| Cost of Production/kg of Dry Harvest = PhP 4.00 (US$ 0.154). | |||
(Cost of drying, packaging, handling, and freight not yet included). | |||
Assuming that the cost of drying, packaging, handling, overhead and freight is two times the cost of producing the seaweeds in the farm, then the CEBU price would be only about US$ 300/mt. If we add a profit of US$ 100/mt, the EXPORT PRICE would be only US$400.00/mt. Still much cheaper than the current price of US$ 800–1,000/mt.
