Monthly Archives: August 2011

2011 releases

AEM 52 Breeding and seed production of the giant freshwater prawn (Macrobrachium rosenbergii) 

Maria Lourdes Cuvin-Aralar, Manuel Laron, Emiliano Aralar, Ursan de la Paz (2011) 33 pp

An extension manual describing biology, broodstock management, hatchery & nursery operations, feeding management, packing & transport, and health management of the giant freshwater prawn.

Each copy costs US$6

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Health Management in Aquaculture 

Gilda Lio-Po and Yasuo Inui eds. (2011) 316 pp

A textbook on the major diseases of cultured fish & crustaceans, as well as prevention & control methods and diagnostic techniques for these diseases. New chapters on histology, probiotics, and epidemiology were added in this edition.

Each copy costs US$65

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RTC-cover Sustainable aquaculture development for food security in Southeast Asia towards 2020  

Belen Acosta, Relicardo Coloso, Evelyn Grace de Jesus-Ayson, Joebert Toledo (2011) 169 pp

This documents the proceedings of the Regional Technical Consultation on Sustainable Aquaculture held 17-19 March 2011 in Bangkok, Thailand.

Each copy costs US$16

AEM 51 Modyular na pag-aalaga ng tilapya sa mga kulungang lambat 

Ruel Eguia, Maria Rowena Romana-Eguia, Nerissa Salayo (2011) 27 pp

An extension manual detailing traditional cage culture method, concept of modular cage culture, economic feasibility of modular cage culture, and post harvest processing.

Each copy costs US$5

AEM 50 Cage culture of the giant freshwater prawn (Macrobrachium rosenbergii) 

Maria Lourdes Cuvin-Aralar, Emiliano Aralar, Alma Lazartigue (2011) 30 pp

An extension manual describing biology, site requirement, grow-out operations, health management, harvest, post harvest handling & processing, and economic analysis.

Each copy costs US$5

Life cycle of mud crab 

36 x 24.5 in (2011)

Color poster conceptualized by ET Quinitio.

Each copy costs US$6

Highlights-2010-cover AQD Highlights 2010 

A 52-page report of AQD’s accomplishments in R&D in 2010.

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petron-project-cover Pilot project on milkfish culture as livelihood option for Guimaras fisherfolk 

A two-page three-fold flyer on the collaborative project among Petron Foundation, Citi Foundation, AQD, and the Municipality of Nueva Valencia.

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climate-change-flyer-cover SEAFDEC/AQD responds to climate change through responsible aquaculture 

A two-page flyer on climate change.

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TMS-flyer-cover SEAFDEC/AQD Tigbauan Main Station 

A two-page visitor flyer on AQD’s station.

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BFS flyer cover SEAFDEC/AQD Binangonan Freshwater Station 

A two-page visitor flyer on AQD’s station.

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DBS flyer cover SEAFDEC/AQD Dumangas Brackishwater Station 

A two-page visitor flyer on AQD’s station.

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IMS-flyer-cover SEAFDEC/AQD Igang Marine Station 

A two-page visitor flyer on AQD’s station.

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September 2011

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August 2011 

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AQD-Matters5_July2011 July 2011 

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AQD-Matters4_June11 June 2011 

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AQD-Matters3_AprMay2011 April-May 2011 

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AQD Matters2_FebMar2011 February-March 2011 

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January 2011 

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Brackishwater pond culture of mud crab

A mudcrab pen at low tide among the mangroves in Aklan

Technology Description

Mudcrab has ceased to be an incidental crop in milkfish or shrimp ponds, and is no longer considered a nuisance species which burrows and destroys fishpond dikes. With a new technology, especially on pond design, mudcrab can be successfully grown on its own in brackishwater ponds.

 
 
Mudcrab from the wild or from the hatchery may be stocked in brackishwater ponds at a stocking density of 5,000 to 10,000 per hectare. These ponds have to be carefully prepared, including the digging up of trench canals parallel to the dikes when polycultured with milkfish so that crabs do not have to be exposed to high temperatures. In monoculture, trenches are not needed but ponds should be provided with water depth of 80-100 cm. Shelters would also be provided. Gracilaria has been found to effectively provide refuge for moulting and post-moult crabs, thus reducing cannibalism among crabs in ponds. The seaweed must be planted in advance. To prevent escape of crabs, each pond is fenced by bamboo or nylon net, and above the water line, a plastic sheet covers the bamboo support. Trash fish is usually fed, at 10% of crab body weight initially, then gradually reduced to 8% and finally 5%. Water management is based on the tides. Selective harvesting is best. Culture period lasts 4-5 months.

Technology profile:
(1) Prepare the mudcrab pond like you would for milkfish in polyculture system or shrimp for monoculture of crabs. Install nets. 

(2) Stock mudcrab juveniles, of size 10-40 g or 5-20 cm carapace breadth, at a rate of 5,000 to 10,000 per ha. It is best to stock monosize crabs to obtain a relatively uniform size at the end of the rearing period.

(3) Care for the stock by regularly changing water following the tidal cycle. When crabs cling onto bamboo supports or nets, water condition is not favorable.

(4) Feed trash fish, snails, and other locally available materials for the carnivorous crab. Broadcast the feed twice a day. An initial feeding rate of 10% of total crab biomass is given, later reduced to 5% as the crabs grow older. They won’t need so much food once their growth spurt passes.

(5) Select and remove marketable size and “fat” crabs several times over the grow-out culture period: >300 g female and >400 g male for pulang alimango or the native crabs, and >400 g female and >500 g male for giant crabs. Selective or progressive harvest minimizes competition for food and space and reduces the incidence of cannibalism.

6) To selectively harvest, scoop up the crabs while they congregate near the pond gate as you let in the water. Crabs swim against the current. Then, use lift nets for the remaining crabs as soon as the water levels off.

(7) To harvest totally after the 120-150 days culture period, drain the pond and catch the crabs manually.

(8) Be careful not to damage the crabs, and keep them moist by placing mangrove fronds in the harvest container and
pouring pond water over them. Tie them up.

 
References

Agbayani RF.  2001.  Production economics and marketing of mud crabs in the Philippines. Asian Fisheries Science 14:201-210

Agbayani RF, Baliao DD, Samonte GPB, Tumaliuan RE, Caturao RD.  1990.  Economic feasibility analysis of the monoculture of mudcrab (Scylla serrata) Forsskal.  Aquaculture 91:223-231

Baliao DD, de los Santos MA, Franco NM. 1999. Mudcrab, Scylla spp, production in brackishwater ponds. Aquaculture Extension Manual No. 28, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 14 p

Baliao DD, de los Santos MA, Franco NM. 1999. Pen culture of mudcrab in mangroves. Aquaculture Extension Manual No. 26, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 10 p

Millamena OM, Bangcaya JP.  2001.  Reproductive performance and larval quality of pond-raised Scylla serrata females fed various broodstock diets. Asian Fisheries Science 14:153-159

Mudcrab culture. 1999. A 3-fold flyer downloadable from the SEAFDEC/AQD website

Mudcrab culture. SEAFDEC Asian Aquaculture 19 (3, August 1997): p 10-25

Rodriguez EM, Quinitio ET, Parado-Estepa FD, Millamena OM.  2001.  Culture of Scylla serrata megalopa in brackishwater ponds. Asian Fisheries Science 14:185-189

Rodriguez EM, Triño AT, Minagawa M.  2003.  Diet and harvesting regimen for the production of mudcrab Scylla olivacea in brackish water ponds. Fisheries Science 69:37-42

Triño AT, Millamena OM, Keenan CP.  2001.  Pond culture of the mud crab Scylla serrata (Forskal) fed formulated diet with or without vitamin and mineral supplements. Asian Fisheries Science 14:191-200

Triño AT, Millamena OM, Keenan C.  1999.  Commercial evaluation of monosex pond culture of the mudcrab Scylla serrata species at three stocking densities in the Philippines.  Aquaculture 174:109-118

Triño AT, Rodriguez EM.  2001.  Mud crab fattening in ponds. Asian Fisheries Science 14:211-216

Trino AT, Rodriguez EM, Coniza EB, Juanga BP. 1999. Mudcrab. Aquaculture Extension Manual No. 27, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 34 p

Crab fattening in cages/pen culture of crabs in mangroves

A mudcrab pen at low tide among the mangroves in AklanTechnology description

To produce food through aquaculture without sacrificing the environment is an apt description for the culture or fattening of mudcrab in mangrove areas. The use of net enclosures in mangroves or tidal zones offers a better alternative to pond culture. It also promotes a better image for brackishwater aquaculture that had been linked to the historical clear-cutting of mangroves to make way to ponds.

For fattening, the technology involves the construct of small cages with individual cells which are then stocked with lean crabs, weighing at least 100 g (if female native crabs) or 300 g (if female giant crab). Males weighing 200 g (if native) or 350 g (giant crab) may also be stocked individually in the cage cells. Fattening can take 15-30 days.

Pen culture of mudcrab, on the other hand, entails the enclosure of mangrove stands with bamboo-supported netting. The shape of the enclosure may be irregular, depending on the location of the mangrove trees. Or, rectangular net pens may be constructed, complete with walkways, particularly in or around new reforested mangrove areas. Culture can take 150 days.

The crab farmer follows a protocol in taking care of the stock, from stocking to feeding to selective harvest.

The culture system used is monoculture in cell-type cages or pens, and may be implemented in mangrove areas. Medium-sized crabs to be used for stocking may be obtained through crab trapping or from fishponds. Feeds, usually trashfish, are bought in from the local market.

 

Technology profile:
mudcrab_cageFattening in cages with individual cells
(1) Construct a bamboo cage (0.25 x 0.7 x 2m;) with a green nylon net (12 mm mesh size) for side walling, bottom flooring and top movable cover. Make three main divisions, further dividing into eight cells. A cage would have 24 cells. Provide cage with floats and rings in the corners. 

(2) Set or stake the cage at the fringes of the mangrove area, such that, at the lowest tide, ¾ of the cage is still submerged. Cover cage with coconut fronds as crab shelter.

(3) Stock one crab per cell, and feed with trash fish or mixed diet of 75% brown mussel meat and 25% trash fish at 10% of the crab biomass per day.

(4) Selectively harvest and restock harvested cages. Fattening can take 15-30 days.

Pen culture in mangroves
(1) Construct net enclosures with bamboo as structural support, and line the inner side of the upper end with plastic sheet to prevent crabs from escaping. The bottom of the net is buried in the ground. Height of the enclosure should be 30-40 cm above the highest tide. 

(2) Of the 0.2 ha area, allocate 20-30% to peripheral and central canals (100 cm wide x 50 cm deep). Dig the canals between mangroves without damaging main roots. Canals are intended to retain 50 cm water during lowest tide. Allow water to flood and drain with the tides. It is important for mangrove roots to be exposed as continuous submergence will cause their death.

(3) Acclimate crabs by pouring seawater over them. Sort males from females, and stock separately. Stock similar-sized crabs of the same species in the same pen to reduce fighting and cannibalism. Stock at 5,000 lean crabs per ha.

(4) Monitor water quality, watch for signs of diseases and abnormalities, and feed the crabs. Feeds used include trashfish and mussel meat which are given at 10% of crab biomass per day. Give 40% of the feed early in the morning and the rest in late afternoon.

(5) Do monthly weight and carapace length measurements to adjust feed ration.

(6) Selectively harvest marketable-sized crabs.

 
References:

Agbayani RF.  2001.  Production economics and marketing of mud crabs in the Philippines. Asian Fisheries Science 14:201-210

Baliao DD, de los Santos MA, Franco NM. 1999. Mudcrab, Scylla spp, production in brackishwater ponds. Aquaculture Extension Manual No. 28, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 14 p

Baliao DD, de los Santos MA, Franco NM. 1999. Pen culture of mudcrab in mangroves. Aquaculture Extension Manual No. 26, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 10 p

Mudcrab culture. 1999. A 3-fold flyer downloadable from the SEAFDEC/AQD website www.seafdec.org.ph/publications_downloadable.html

Mudcrab culture. SEAFDEC Asian Aquaculture 19 (3, August 1997): p 10-25

Primavera JH, Garcia LMB, Surtida MB, Castanos MT. 2000. Mangrove-friendly aquaculture. SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 217 p

Triño AT, Rodriguez EM.  2001.  Mud crab fattening in ponds. Asian Fisheries Science 14:211-216

Trino AT, Rodriguez EM, Coniza EB, Juanga BP. 1999. Mudcrab. Aquaculture Extension Manual No. 27, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 34 p

Hatchery & nursery of mud crab

Crablets produced from the AQD hatcheryTechnology description

Although the technology applies to all three species of mud crab (Scylla serrata, S. tranquebarica, S. olivacea), S. serrata or giant/king crab has been the focus of culture due to its economic viability. Healthy mature crabs with complete limbs are chosen as breeders. The crabs are maintained in the tank until they spawn (release of eggs). After hatching of eggs, care is taken to raise the zoea to the megalopa stage in the hatchery. Feed used are Brachionus and Artemia. Water replacement may be from 30 to 80% every 5 days. Megalopae are then transferred to nursery tanks or net cages before they can be stocked in ponds or pens, and are fed mollusks or fish. Hatchery and nursery can take 52-55 days.

Technology profile:

(1) Gather several female crabs with fully mature ovaries (orange ovaries), at least ≥500 g or 12.5 mm carapace width for S. serrata; 320 g or 12.2 mm S. tranquebarica; 320 g or 11.5 mm S. olivacea. 

(2) Acclimate by pouring water over the crabs in a basin every 5 minutes for about 30 min. Transfer crabs to a basin containing 150 ppm formalin for another 30 min to disinfect before stocking in aerated broodstock tanks.

(3) After allowing crabs to recover from handling and transport stress, ablate one eyestalk of immature crabs (with yellow ovaries) using a sterilized blade to incise and a red-hot forceps to clip off. Apply terramycin ointment to the wound. Allow crab to recover in a small volume of seawater (so as not to wet its wound) before putting back to broodstock tank. Cover the tank.

(4) Crabs spawn within 2-4 weeks. To care for berried crabs (females with eggs attached to the abdominal flap), feed them mussel,  fish or marine worms at 10-15% of biomass daily.

(5) Remove uneaten food and feces daily. Discontinue feeding after 5-6 days or when the egg mass turn brown. Change 50- 80% of water volume daily. S. serrata produce 0.8 to 5 million zoeae per spawning; S. tranquebarica between 0.7 to 3 million; and S. olivacea between 0.4 to 2.7 million.

(6) Collect zoeae within an hour of its appearance to prevent microbial attack. Stock in larval rearing tanks at 50-80 zoeae per liter. Feed with rotifers, maintaining a density of 10-15 Brachionus per ml in the first 10 days. Give newly hatched Artemia in the late zoea stage (0.5-1 per ml), and larger ones in the megalopa stage (feed to satiation twice daily). Maintain good water quality.

(7) Transfer megalopae to bigger tanks or net cages after about 21 days. Stock at 1-2 per liter in 10-ton tanks, or 50-70 per sq. m in cages. Feed 5-7-day-old Artemia, later adding minced trash fish, small
shrimps, and mussel.

(8) About 52 days from hatching, the crab juveniles can be harvested, packed and transported to ponds or pens for grow-out culture.

 
References:

Catacutan MR.  2002.  Growth and body composition of juvenile mud crab Scylla serrata, fed different dietary protein and lipid levels and protein to energy ratios.  Aquaculture 208:113-123

Catacutan MR, Eusebio PS, Teshima S.  2003.  Apparent digestibility of selected feedstuffs by mud crab, Scylla serrata. Aquaculture 216: 253-261

Lavilla-Pitogo CR, de la Pena LD. 2004. Diseases in farmed mud crabs Scylla spp.: diagnosis, prevention and control. SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 89 p.

Lavilla-Pitogo CR, Marcial HS, Pedrajas SAG, Quinitio ET, Millamena OM.  2001.  Problems associated with tank-held mud crab (Scylla spp.) broodstock. Asian Fisheries Science 14:217-224

Leaño EM.  2002.  Haliphthoros spp. from spawned eggs of captive mud crab, Scylla serrata, broodstocks.  Fungal Diversity 9:93-103

Millamena OM, Quinitio ET.  2000.  The effects of diets on reproductive performance of eyestalk ablated and intact mud crab Scylla serrata.  Aquaculture 181:81-90

Quinitio ET, Estepa FD. 2003. Biology and hatchery of mud crabs Scylla spp. Aquaculture Extension Manual 34, SEAFDEC Aquaculture Department, Tigbauan, Iloilo. 42 p

Quinitio ET, Parado-Estepa FD.  2000.  Transport of Scylla serrata megalopae at various densities and durations.  Aquaculture 185:63-71

Quinitio ET, Parado-Estepa FD.  2001.  Simulated transport of Scylla serrata zoeae at various loading densities. Asian Fisheries Science 14:225-230

Quinitio ET, Parado-Estepa FD, Millamena OM, Rodriguez EM.  2001.  Seed production of mud crab Scylla serrata juveniles. Asian Fisheries Science 14:161-174

Peñaflorida YD.  2004.  Amino acid profiles in the midgut, ovary, developing eggs and zoea of the mud crab, Scylla serrata. Israeli Journal of Aquaculture – Bamidgeh 56:113-125

Virus expected to cost Australian abalone industry

Virus expected to cost Australian abalone industry
A herpes-like virus in wild and farmed abalone stocks are wreaking havoc, which could cost the abalone industry in south-west Victoria in Australia up to $5 million in losses this season.
The virus responsible for ganglioneuritis, as reported here, is believed to have come from an aquaculture facility in Portland, moving east. Ganglioneuritis causes inflammation of abalone nervous tissue, resulting in curling of the foot and swelling of the mouth.

Stakeholders are not very optimistic in their outlook about the situation; divers, such as Peter Riddle, are angry at the State Government’s handling. He thought that it is “too late” to do anything now, “the disease is in the ocean and I don’t think we’ve got any way” of stopping this threat.

“It’s half my income now and what we worry about is the following years, whether we are going to survive,” he said.

Fisheries Victoria says it is ensuring stocks are fished sustainably.

It says it closed the Portland facility when it was alerted to the outbreak to try to contain the disease.

Actions were taken to control the disease, which include the disinfection and decontamination of abalone farms. Biosecurity protocols for the recreational, commercial and aquaculture sectors were also developed.

Abalone is the basis of Victoria’s most valuable commercial fishery with a landed value in excess of $60 million per year in the last two years, according to Victoria’s Department of Primary Industries.

Considering that the Philippines is not that far away from Australia is enough reason for the industry to be concerned.
Sources: http://www.abc.net.au/news/newsitems/200702/s1842308.htm, February 7, 2007. 2:48pm (AEDT)
http://www.dpi.vic.gov.au, January 23, 2007.

Abalone: don’t cramp my style

Abalone: don’t cramp my style
Cramped spaces leave abalones with little room for attachment and feeding
Abalone farming is a growing aquaculture industry. New frontiers are being explored to expand the production of this valuable commodity, which has various researchers testing the waters in terms of culturing the tropical abalone Haliotis asinina in sea cages. Since studies have shown that stocking density has an inverse relationship with the growth of abalone, the trick is to find a middle ground wherein a given area could still be able to support the growth of abalone.

 

This begs the question: Does the shelter surface area (SSA) of mesh cages have an effect on the feeding, growth and survival of the tropical abalone? To find out, Armando Fermin and Shela Mae Buen of SEAFDEC/AQD embarked on the study by stocking cages with different-sized shelters measuring 0.22, 0.44 and 0.66 sq. m with 227, 113, and 75 abalones, respectively. Other provisions like adequate aeration and feeding with the seaweed Gracilariopsis bailinae were also given.

 

The experiment, conducted in 270 days, showed that shell lengths, body weights and daily growth rates were not significantly different in the first 13 weeks of culture. Abalone grown in cages with SSAs of 0.22 and 0.44 sq. m had higher feeding rates. In spite of this, the abalones reared in cages with 0.66 sq. m SSA were found to grow significantly faster by the fourth culture month. By harvest time, body size was significantly different between the cages with the largest and smallest SSAs.

 

Why the difference? The higher shelter surface area-to-cage volume ratio had a significant effect on the growth of H. asinina. Limited attachment space in the cages with smaller SSAs caused the abalone to stick to one another, thereby restricting movement and feeding of the abalone located underneath.

 

It is always important, therefore, to increase the area for abalone attachment to overcome the abalone’s tendency to stack.

 

Read more from the journal Aquaculture International (2002) 9: 499-508.

In abalone culture, omnivores rule

In abalone culture, omnivores rule
Diets with both plant and animal sources strike the perfect balance between nutritive content and cost
A prized aquaculture commodity, the tropical abalone Haliotis asinina has a high market demand in both local and export markets. Because of this, researchers are trying to come up with diet formulations that could support greater growth while minimizing feed cost.

Abalones are herbivores in their natural habitats, feeding mostly on macroalgae like seaweeds. In the culture environment, however, experiments from Taiwan have noted that abalone juveniles fed formulated diets had 65% greater growth than those fed solely with macroalgae. In addition, they were found to contain relatively higher protein content than the seaweed-fed abalone.

Formulated feed must contain sufficient nutrients like protein and amino acids to encourage growth of H. asinina. Palatability, digestibility and the presence of the right balance of amino acids are important considerations in choosing the protein source to be incorporated in the artificial diet.

The study conducted by Myrna Bautista-Teruel and colleagues of SEAFDEC/AQD focused on the development of practical diets for the abalone, with emphasis on the determination of suitable protein sources such as fish meal, defatted soybean meal and the blue-green alga Spirulina sp. for incorporation in the formulated diets.

In their tests, the proponents prepared four practical diets. Diet 1 consisted of either fishmeal (FM), shrimp meal (SM) and defatted soybean meal (DSM) as the main protein sources. Diet 2 was composed of FM and DSM, Diet 3 was made up of DSM and SP, and Diet 4 consisted of FM, SM, and SP at 27%. These were then fed to abalone juveniles under controlled environments.

Eighty-four days later, results showed Diet 2-fed abalone to have the highest weight gain of 453.8%. However, the results were not significantly higher than those fed with Diet 4. Diet 3 registered lower weight gain, growth rates and length gains in abalone. The results showed that a feed protein from a combination of plant and animal sources promoted better growth rates than those prepared from plant origins alone. One of the reasons cited for this is that Diet 3 had low levels of the essential amino acid methionine, which are found in larger amounts from animal sources.

Since the reliance on animal-based feed diets alone could prove expensive, combining them with plant-based protein sources could strike the perfect balance between sustained growth rates and minimal cost.

Read more of this article from the journal Aquaculture (2003) 219: 645-653.

Abalone: feed, mark, let go

Abalone: feed, mark, let go
A safer and easier way of tagging abalone for stock enhancement is feeding them a formulated diet
In the wild, abalone population has been declining. One way of replenishing this is through stock enhancement in marine reserves, sanctuaries or other protected areas. One way of determining the activity’s success is by monitoring tagged abalones after they are released in the wild. And therein lies the problem: the lack of effective tagging or marking methods.

Ideally, tags used in stock enhancement should be able to mark small individuals, detectable in other life stages, is unique to the local population, and suitable for identification of individuals from particular releases. Tags should also be inexpensive to apply and detect, could be transmitted to subsequent generations, should not harmful to the tagged abalone and people, and acceptable to the public.

Wenresti Gallardo and his colleagues at SEAFDEC/AQD studied the ways to meet the above-mentioned requirements. While they have noted that tagging methods for abalone exist, these were usually labor-intensive and either results in irritation to the abalone or the loss of tags. One possible alternative to existing methods is diet-tagging, an idea that came up when they saw green bands on abalone that had been fed formulated feeds in the hatchery. Wild stocks do not have such bands, and the only difference between wild and hatchery-held abalone was their diets.

In their research, they fed abalone juveniles daily with a SEAFDEC-formulated diet at 5% of body weight, After three weeks, when a bluish-green shell band was observed, the abalone were given Gracilaria bailinae for two months to produce the normal brownish shell after the bluish-green band. The control setup was fed only with liberal servings of G. bailinae. Abalone were then stocked in outdoor tanks and in a marine reserve to observe any color changes in the shells.

Eighteen months after, the researchers noted that the bluish-green band in abalone fed formulated diets remained distinct, and they could be distinguished from the seaweed-eating abalone in both the outdoor tank and marine reserve habitats. This could be due to the presence of pigments in some of the ingredients of the formulated feed.

Diet-tagging is a step in the right direction for researchers and stakeholders intent on determining the success or failure of abalone stock enhancement efforts. Although it could take some time, this method is perhaps the most painless procedure for the abalone, who need the least amount of stress in their new habitats.

Read more from the journal Aquaculture Research (2003) 34: 839-842.

Papaya, malunggay, ipil-ipil and Azolla: must-haves for abalone?

Papaya, malunggay, ipil-ipil and Azolla: must-haves for abalone?
Abalone need green leafy “vegetables,” too
Abalone, being herbivores, are known to feed on seaweeds in the wild. However, seaweeds like Graciliariopsis bailinae are economically important in themselves, being sources of valuable agar. Seaweeds just can not be used as feed. Hence, locally available plants may just be the right supplement or replacement for expensive components in formulated feeds for abalone.

In the Philippines, the terrestrial plants Carica papaya, Leucaena leucocephala, Moringa oliefera, locally known by their less-daunting names papaya, ipil-ipil, and malunggay, respectively, may be the ideal candidates for this purpose. A freshwater fern, Azolla pinnata, is another potential alternative, being incorporated in the diets of tilapia and carp to promote their growth.

A study conducted by SEAFDEC/AQD’s Ofelia Reyes and Armando Fermin tests this idea. About 13% of the total 27% crude protein of formulated diets come from the plant meals. The formulated diets were fed daily to juvenile abalones stocked in fifteen 60-liter fiberglass tanks at 2-3% of their body weights, while the control feed consisting of fresh Graciliariopsis bailinae was given daily at 30% of the total body weight.

After 120 days, the results were in: specific growth rates of abalone fed M. oliefera and A. pinnata were significantly higher than those fed L. leucocephala, but not to those fed fresh G. bailinae. In terms of weight, diets based on M. olifiera, A. pinnata and fresh G. bailinae showed greater gains compared with the L. leucocephala-based diet. Abalone fed M. oliefera also had a significantly higher protein productive value (PPV) of 79.9, while the rest had values 57.3 or lower, with that of G. bailinae having the lowest value of only 12.3.

Why the results? The higher growth rate of M. oliefera- and A. pinnata-fed abalone could be due to the physical characteristics of the leaves, having softer textures and less fiber compared to the other leaf meals. M. oliefera is also rich in the minerals calcium, iron and phosphorous, which could have improved the nutritive value of the diet. On the other hand, L. leucocephala contains the anti-nutritional factor mimosine, which could still have been present in the diet. This explains why abalone fed this treatment had the lowest weight and length gains.

Given that one of the main concerns in the culture of abalone is the high cost of feed, it would not hurt if the commonly-found M. oliefera and A. pinnata be used as one of the ingredients of diets for abalone. Not only are they available year-round, they also contain essential nutrients to support the growth of H. asinina.

Read more from the journal Aquaculture Research (2003) 34: 593-599.

Navicula + abalone mucus = high metamorphosis

Navicula + abalone mucus = high metamorphosis
One of the major problems that have perplexed abalone hatchery operators is the poor settlement or the attachment and metamorphosis of abalone larvae. To increase the production of seeds needed for stock enhancement, suitable inducers for the settlement of abalone larvae have to be provided.

Since tests using different abalone species showed that responses to settlement cues vary depending on the species, Wenresti Gallardo and Shelah Mae Buen-Ursua of SEAFDEC/AQD decided to test the effect of larval settlement inducers on the tropical abalone Haliotis asinina.

Inducers tested included abalone mucus, Navicula sp., Navicula + mucus, mixed diatoms, and mixed diatoms + mucus. Variables requiring mucus were produced by allowing a juvenile abalone to crawl for one hour into treated Petri dishes, while the other samples that did not require the mucus were prepared using certain laboratory procedures. Four Petri dishes of each treatment and control were randomly placed on the bottom of each of the five 60-liter fiberglass tanks, which contained 30 liters of treated seawater. Larvae, which were stocked at 200 per liter, were counted and monitored during the experiment.

The three trials conducted had a common ground, wherein the type of settlement substrate had a significant effect on larval attachment. Of the five treatments used, abalone had greater attachment on mucus, Navicula, Navicula + mucus, and mixed diatoms + mucus on Day 1 of the study. By Days 3 and 7, the Navicula and Navicula + mucus treatments resulted in higher live abalone postlarvae compared to the other treatments. By Day 10, the Navicula + mucus treatment registered the highest number of fully metamorphosed postlarvae.

The authors think that the higher larval attachment to the samples mentioned above could be due to the abalone mucus, which acts as an attractant for larval attachments. Since mucus consists primarily of proteins and polysaccharides, this material, also produced by other marine gastropods like sea slugs, could have positive effects on abalone metamorphosis. It is also possible that the mucus secreted by Navicula has had a hand in the good results for Day 1. Furthermore, factors such as the uniform cells and prostate type of cell growth of Navicula make it a suitable attachment. Although Navicula was the dominant species in the mixed-diatom treatment, the presence of three-dimensional species like Melosira, Thalassiothrix and Fragilaria may have prevented the attachment of the abalones, which suggests that being one-dimensional isn’t so bad if you’re a diatom. In addition, other researches have noted the high nutritional value of Navicula.

Given these results, the authors suggest that techniques for the mass culture of Navicula on settlement plates be developed, and that these be grazed by abalone juveniles to produce the best possible outcome.

Read more from the journal Aquaculture (2003) 221: 357-364

Substrate matters

Substrate matters
Even bottom feeders like abalone know the importance of good substrates
Marine invertebrates use a range of physical, biological and chemical signals to influence their metamorphosis and larval settlement. In the abalone hatchery environment, these could include food sources and appropriate substrates.

To determine what combination of substrate and food source is best for abalone larvae, Rolando Gapasin and Bernice Polohan of SEAFDEC/AQD subjected Haliotis asinina postlarvae to different “substrate-diatom” complexes, together with gamma-aminobutyric acid or GABA. Substrates made of plexiglass, rubberized canvas, fibrocement board and corrugated plastic were placed on the floor bottom of four plexiglass aquaria. Each of these were then inoculated with the following diatom species: Amphora sp., Nitzchia cf. frustulum, a 1:1 combination of Amphora and Nitzchia, and diatom “slurry” composed of Amphora, Coscinodiscus, Coconeis, Nitzchia, Diploneis and Mastolia.

Based on the results of two trials, abalone larvae apparently preferred their diatom slurry served over roughened plexiglass in combination with GABA; around 27% and 20%, respectively, of abalone larvae metamorphosed using this combination of substrate-diatom complex. The others did not fare as well: among the diatoms, Nitzchia cf. frustulum gave the lowest percentage of metamorphosed larvae, while fibrocement was the lowest-testing of the four substrates.

What accounted for the difference? The proponents speculate that the amount of extracellular substances produced by Nitzchia cf. frustulum may not have been enough to sustain the abalone postlarvae. This species may have exhibited low digestion efficiency, or that sub-optimal culture conditions may have contributed to poor growth of the diatom, which led to poor settlement and metamorphosis of the abalone. Also, since it was found that postlarvae preferred crustose coraline algae together with its associated benthic diatoms in their natural habitat, the roughened plexiglass was probably the next best thing in a culture setting.

The results given should serve as cues for abalone postlarvae growers to make modifications if necessary to ensure optimum growth of their stocks.

Read more of this research from the journal Hydrobiologica (2005) 548:301-306.

Abalone: we need our space

Abalone: we need our space!
For abalone to grow well, low stocking rate is good, high stocking bad, and reduced oxygen downright ugly
As one of the major countries harvesting abalone, the Philippines is mostly dependent on wild catch since commercial grow-out system for Haliotis asinina is still a pioneering effort. Due to the low profit margin in land-based culture systems, alternative means such as sea cages are being pursued. 

A study conducted by Emmanuel Capinpin Jr and his colleagues determined the effects of different stocking densities on the growth, feed conversion ratio (FCR) and survival of abalone using the cage system. Employing three trials using different stocking densities, the researchers raised abalone, with sizes ranging from 16-20 mm and 35-40 mm in 40 x 40 x 20 cm net cages suspended from floating rafts at SEAFDEC/AQD’s marine substation in Guimaras, west central Philippines. The abalone were fed the red alga Gracilariopsis bailinae.

The trials, which lasted for as long as 180 days, were consistent in one aspect: regardless of time period, there were no significant differences in the survival rate and FCR. However, the study did show that daily growth rates in both weight and height were higher in cages with lower stocking density.

Why the difference? The study suggests that there is an inverse relationship between growth and stocking density, which means that the lower the stocking density, the greater the growth of the abalone. The cramped space causes the abalone to stack due to lack of space for attachment, which in turn hinders their ability to move and ingest food, thus, the lower growth rates. In addition, increased levels of metabolic wastes and reduced dissolved oxygen, which result from higher densities, also lead to poor growth. A balance between stocking density and area for culture should be attained to maximize profit.

Technology adopters will no doubt be encouraged to venture into this endeavor once the results of the economic analysis is found satisfying.

This research on sea cage culture of abalone has been published in the journal Aquaculture (1999) 171: 227-235.

Abalone grow-out culture


Feeding in the grow-out cages  

Technical Assumptions


Initial size

2.0
cm, 1.5 g (P5/pc)

   

Final
size

5.5
cm, 50 g (P300/kg, 20 pcs/kg)


Culture period (months)

9

Seaweed price (P/kg)

4


Number of crops/year

3-4


Survival rate (%)

90%


Feed Conversion Ratio

20-25


Project Duration (years)

4

  Investment


Capital outlay 



30,000


Mesh cages

19,600


Long line


7,400

Anchors


2,000


Other materials


1,000


Investment cost (x 3 crops (VC))

98,640


Abalone juveniles 


21,000

Salary, extra labor


1,860


Seaweeds


10,020


Total capital investment required

128,640

  Costs-and-Returns



Item


1 module


Revenue/crop
(189 kg/module x P300/kg)


56,700


Variable cost (P)


32,880

Fixed
cost (P)


10,112

Total
production cost (P)


42,992

Net
income/crop (P)

13,707

Net
income/year (P)


41,122


Return on Investment (%)

137

Payback period (months)

7.5

Break
even price (P)

227

Break
even production (kg)

143

  Financial Investment Analysis


Project Duration


4


Total number of harvests


14


Gross revenue


793,800


Investment cost


30,000


Total cost


601,896


Net income


161,904


NPV at 12%


100,053


IRR(%)


124.87


BCR


4.74

Abalone hatchery & nursery


Feeding in the grow-out cages      

Technical Assumptions


Project duration

5
years


Number of breeders, female + male (70-80g)


800+200 pcs

Group
spawning frequency per month

  2x

Number of spawning breeders/month

256

Ave.
spawning fecundity per breeder


250,000 eggs

Total
egg production/spawning cycle

32
million

Total
veliger larvae production (40%)

12.8
million

%
Settlement rate

2.50%

%
Survival of early juvenile at 90-day period

4%

Total
early juvenile production per run
(10-15mm)


12,800

%
Survival after a 60-day nursery 

85%

Total
advance juveniles production per run
 (20-25mm)

10,880


Number of production cycles per year

20

Total
juvenile production per year


217,600

  Investment


Capital Investment


1,061,000


Annual Depreciation


93,942


Depreciation per crop

4,697


Salvage Value after 5 Years


602,125

  Costs-and-Returns

Items

 
Harvest, 90-day
(10-15 mm SL)


      Harvest, 150-day

( 20-25 mm SL)

 Per
crop

Per
year

Per
crop

Per
year


Hatchery production 


12,800


256,000


10,880


217,600

Gross
Revenue:

 

 

 

 

Sale
of juveniles (P6/pc; P8/pc)


76,800


1,536,000


87,040


1,740,800

Variable costs


19,037

380,740


23,933

478,660

Fixed
costs


10,215


204,302


10,215


204,302

Total
cost


29,252


585,042


34,148


682,962

Net
Income


47,548


950,958


52,892


1,057,838

  Economic Indicators

Items



Harvest, 90-day


(10-15 mm SL)

 Harvest,
150-day
( 20-25 mm SL)

Net
profit per year (before tax)


950,958

1,057,838


Return on Investment (ROI, %)


101.48


111.56


Break-even-Quantity (pcs)

97,507


113,826


Break-even-Price (Pesos) 

2.29

3.14


Payback period (Years)

1.02

0.92

  Financial Investment Analysis

Items


Harvest, 90-day


Harvest, 150-day


Project duration

  5
years

    
5 years

Investment Cost


1,061,000

1,061,000

Gross
Revenue


1,280,000


1,740,800

Total
Cost (variable+fixed)


585,042


682,962

Net
Income


950,958


1,057,838

NPV @
12%

3,430,242


3,873,490

IRR
(%)

98.49

109.24


Discounted BCR

3.62

4.09

  Updated: January 23, 2008
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