Ensuring food safety through sustainable aquaculture methods Healthy and Wholesome Aquaculture

In order to attain significant improvements and sustain aquaculture production in the face of many challenges posed by present and future ecological, economic as well as climatic changes, AQD invoked strategies to promote healthy farmed aquatic animals with emphasis on nutrition; disease diagnosis, control, monitoring and surveillance of aquatic animals; and environmental integrity, certification, and food safety. The optimization and sustainability of aquaculture production shall be based on the Best Management and Good Aquaculture Practices to ensure the least impact on the environment. The two components of the Program are: (1) fish health and (2) feed and nutrition.

o Promoting wider use of conventional and new diagnostic methods for new emerging diseases and biosecurity

Tilapia Lake Virus (TiLV), an RNA virus, is an emerging disease that is becoming a serious threat to the culture of tilapia in the Asian countries. To address this concern, AQD carried out studies to detect, quantify and assess the viability of TiLV in pond soil and water influenced by water quality parameters and culture development.

Mangrove crab instars produced at AQD hatcheries Production yield and survival rate of juveniles from stocked veliger larvae was 3.11±1%.

Improved post-larval nutrition was the main contributing factor that led to increased yield of juveniles.

Tilapia (n=123: wild and cage-cultured), soil, and water samples were collected from culture facilities in Tarlac, Pampanga, and Bata-an. Using Quantitative Reverse Transcription - Polymerase Chain Reaction (qRT-PCR) to detect and quantify the virus, results indicated that from the tilapia samples (32 Oreochromis niloticus and 5 Sarotherodon spp.) tested negative using one-step PCR but two were tested positive using nested PCR. RNA was extracted from soil using Phenol-Chloroform-Isoamyl and analysed using semi-nested PCR, and the results showed two out of four soil samples tested positive for TiLV. For water samples, RNA was extracted using QIAamp Viral RNA mini kit and processed using semi-nested PCR, resulting in all water samples tested as negative.

Trial sampling for detection of diseases and pests in seaweeds (farmed and wild) was also conducted to produce detection and molecular diagnostic tools for proper identification of pests and diseases in seaweeds. Samples taken from Inampulugan Island in Guimaras showed that epiphytes were present in both wild and farmed seaweeds. Intensive sampling was then conducted in six sampling sites around Central and Southern Philippines, where epiphytes and ice-ice were observed in the collected samples. An initial batch of seaweed samples was processed for histology and a set of samples are currently undergoing electron microscopy analysis. The identified samples from trial and intensive sampling will be compiled in a central, open-access database and biobanks.

Wild tilapia (O. niloticus) sampled from Laguna de Bay found to be nested PCR-positive for TiLV

Result of one-step (left) and semi-nested PCR (right) for the detection of TiLV in soil, water, cultured and wild tilapia samples

Microscopic view of an unidentified epiphyte with carpogonium (left) and unidentified epiphyte with developing carpogonium (right) in seaweeds

o Finding effective and safe alternative drugs to manage aquaculture diseases

The study to test the efficacy of different therapeutants against Caligus sp. or sea lice in tropical fish under laboratory conditions has been initiated by AQD to investigate the toxic effects of emamectin benzoate in pompano (Trachinotus blochii), determine the effective dose in laboratory assay by exposing pre-adult and adult sea lice collected from infested pompano, and evaluate the efficient oral administration of emamectin benzoate in the control of sea lice infestation in pompano. The pompanos are now being reared to juvenile stages to be used for trials.

Meanwhile, the effectiveness of current biosecurity and legislation on seaweed farming in the Philippines is being determined through a systematic review of the existing legislative policies on seaweed farming (Table 2). Farmers from Zamboanga in the Philippines were then interviewed to assess the: (1) current management biosecurity practices and legislative structures for invasive pests and diseases including the key gaps in these structures; and (2) effectiveness of existing farm management and biosecurity practices including policy and/

or legislation frameworks or structures in seaweed industry compared with other culture systems. Questionnaires were prepared and used for interviewing farmers from three sites (Layag-layag, Tigtabon Island, and Talabaan). Results showed that the attitude scores of all farmers from the three sites do not significantly differ from each other, while the farmers expressed the view that they do not want the government to take charge of the seaweed farming in the country as the government could cause more problems rather than provide actual solutions.

Table 2. List of existing policies and legislations on seaweed farming in Zamboanga, Philippines

Code Title Binding/

Non-binding Explicit/

Non-explicit DA-BFAR FAO No.45 Regulations governing the

gathering of seaweeds producing agar-agar (1956)

B E

DA-BFAR FAO No.108 Regulations governing the gathering and farming of seaweeds (1973)

B E

DA-BFAR FAO No.135 Rules and regulations governing (1981) importation and fishery/

aquatic products

B NE

DA-BFAR FAO No.146 Regulations governing the

gathering of seaweeds (1983) B E

DA-BFAR FAO No.169

and 169-1 Prohibiting the exportation of fresh Eucheuma seaweeds (1990)

B E

DA-BFAR FAO No.221 Rules and Regulations governing (2003) importation and fishery/

aquatic products

B NE

Presidential Decree 1433 Plant Quarantine Law of 1978 B NE BPI Quarantine

Administrative Order 1` Promulgation PD. No. 1433 B NE

o Promoting practices or strategies to improve production

AQD demonstrated the production of whiteleg shrimp Penaeus vannamei using Biofloc System with sludge removal facility in old earthen brackishwater ponds during wet season as well as verified the economic benefits of using the system. For the soil preparation, biosecurity facilities, e.g. bird-scare, crab fence were installed, and pond facilities, e.g. feeding bridge, feeding boat, discharge pipe, depth gauge, secchi disks and others had been fabricated.

Although the ponds are ready for stocking, the shrimp postlarvae (PL) are yet to be delivered, so stocking would commence in early 2019.

Hatchery production and semi-intensive pond culture of white shrimp Penaeus indicus are being improved for sustainable supply. For the hatchery production, broodstocks were sourced from Antique and placed in tanks (10 pairs of male and female). After 30 days of culture, a total of 17,000 PLs were produced. Most larvae were discarded or did not proceed to PL due to lack of diatoms. In the semi-intensive pond culture, growth of shrimp P. vannamei using formulated feeds was compared with those using tilapia feeds. Six ponds (700-800 m²/ pond) at AQD’s Dumangas Brackishwater Station were prepared (cracked dried and applied with lime) with inorganic fertilizers (46-0-0 and 16-20-0), teaseed powder and crustascide.

Each pond was stocked at 20 ind/m² where three ponds are meant for testing P. vannamei feeds and the other three is for tilapia feeds.

o Finding alternative protein sources in dietary formulations

Protein is the most important component of aquaculture feeds and the general source of protein is fish meal (FM), but this commodity is currently expensive and its availability has been predicted to dwindle in the coming years. With this scenario, researches have been conducted by AQD to decrease the FM inclusion in formulations and finding substitutes using new sources without affecting feed efficiency. One usable by-product is the milkfish offal processed into hydrolysate. Tilapia (Orechromis niloticus) larvae given a diet containing 15% milkfish hydrolysate attained similar growth, survival and feed intake with formulation without milkfish hydrolysate. The protein-enhanced copra meal (PECM) was also evaluated as an ingredient in formulated feed for grouper species, Epinephelus fuscogutattus. Performance parameters of grouper were the same at 0-16% dietary PECM and morphology of liver and digestive tract were not altered at all. In E. fuscogutattus, the amino acid leucine requirement for growth was found to be 2.89% of the diet.

Biosecurity fence enclosing the whole production facility (left) and sludge removal facility (SRF) installed in the pond (right)

Processing of raw leaves to powdered spinach: fresh spinach leaves (left), freeze-dried spinach (middle), and spinach in powdered form (right)

Extraction of PCE: Supernatant extracted from the solution (left), sample subjected to rotary evaporator (middle), and dried residues for further solvent extraction (right)

Colloidal and concentrated samples in microtube

after four hours

For feeds of crustacean species, a green macroalgae Chaetomorpha linum is currently being processed for fermentation to increase the levels of nutrients in formulations for the tiger shrimp Penaeus monodon. The mangrove crab Scylla serrata was also studied for possible synchronization of molting since this species is highly cannibalistic and, as such, requires formulated diet to be added with Phytoecdysteroids Crude Extract (PCE) from spinach to induce molting. The application of PCE in the dietary inclusion was administered by injection. Although the extraction of PCE from spinach has improved, the method is currently being refined. In the pond culture of P. indicus, appropriate feed is also being developed for shrimps produced at the hatchery facilities of the AQD’s Tigbauan Main Station and grown into appropriate size for stocking in ponds. Culture in 700 to 800 m² size ponds given two dietary formulations, is ongoing.

Macroalgae being harvested at AQD’s Tigbauan Main Station (left), and a close-up of newly harvested algae (right)

o Determining the specific nutrients that enhance growth performance

Quantifying the requirement for amino acids (leucine, isoleucine and histidine) in Asian sea bass juveniles was carried out by AQD in 2018, however, due to the unavailability of sea bass during the testing period, grouper (E. fuscoguttatus) juveniles were used instead for initial testing of the six diets. For leucine, the levels used were: 0%, 0.25%, 0.5%, 0.75%, 1.0% and 1.25%, where each test diet has amino acid mixture of aspartic acid (13.5%) and Peruvian fish meal with squid meal (60%). Following the eight-week trial, the leucine requirement for grouper was 2.89%, while the proximate composition analysis, amino acid analysis, and protein retention together with more data analysis are still ongoing.

The potential of thraustochytrid as alternative lipid source for fish oil in hatchery-bred abalone (Haliotis asinina) was assessed using abalone juveniles that had been reared to broodstock sizes. The protocol for harvesting cultured thraustochytrid changed from four days to three days, while culture and harvesting of thraustochytrid is ongoing to meet the required amount of extracted thraustochytrid oil.

2.5 Development of responsible and sustainable aquaculture technologies