Seaweeds account for nearly 30% of global aquaculture production by volume, and their cultivation provides important opportunities for employment and wealth generation, particularly in rural coastal communities. Eucheumatoids (Kappaphycus and Eucheuma spp.) are tropical red algae commercially cultivated as raw material for production of carrageenans, particularly in South-East Asia and the Western Indian Ocean region. Diseases and pests are major limiting factors in eucheumatoid production, particularly a condition known as ‘ice-ice’ disease (IID). IID is characterized by bleaching of the thallus followed by the disintegration of affected tissues, leading to a loss of biomass and reduced carrageenan yield. IID has been associated with unfavourable changes in environmental conditions, particularly an increase in sea water temperature and a decrease in salinity, and infection by opportunistic or pathogenic bacteria. However, given that no single or combined causal agents have been definitely identified, IID may be considered a complex pathobiotic syndrome in which multiple factors contribute to the development of disease signs. Here, we review current knowledge of the abiotic and biotic factors associated with the development of IID, and the strategies employed to mitigate economic losses resulting from disease outbreaks. We discuss syndromic diseases in other marine holobionts, particularly other red algae and corals, in relation to their similarity to IID, and suggest the application of comprehensive and complementary methodologies, including high-throughput sequencing and high-quality microscopy, for enhancing our understanding of the pathological and microbiological processes associated with IID signs.

Although the Philippines has a long coastline and is surrounded by rich waters, its capture fisheries subsector is just second to aquaculture which is the main driver for growth in the fish production industry of the country. In 2019, aquaculture production accounted for 53.20 % of the total Philippine fisheries production and the top two aquaculture commodities that the country produced were seaweeds and milkfish. Even though milkfish is among the top two commodities, this does not mean that there are no problems with its production. One of the major aspects that hinder sustainability is the harrowing concern regarding milkfish seed supply which is highly unpredictable. The local production of milkfish fry could not adequately supply the national demand, leading to the import of fry from nearby countries. To reduce the reliance on imports, the Government of the Philippines through its Department of Agriculture-Bureau of Fisheries and Aquatic Resources (DA-BFAR) came up with the “National Bangus Fry Sufficiency Program” with the goal of building legislated multispecies hatcheries in strategic locations in the country. DA-BFAR then tapped the services of SEAFDEC Aquaculture Department (AQD) to provide training and technical assistance, especially in undertaking the feasibility studies of proposed sites where hatcheries are to be established. So far, eight out of the 16 sites have had their feasibility studies submitted to DA-BFAR and their respective local government units (LGUs). To date, there are three ongoing hatchery projects that are in various stages of construction. Out of the three, two are for marine and one is for freshwater aquaculture commodities. In the SEAFDEC/AQD compound, multispecies hatcheries have also been constructed to supply the Western Visayas region with high quality milkfish fry as well as other commodities. Apart from building hatcheries, SEAFDEC/AQD has also partnered with the regional office of DA-BFAR in Western Visayas to revive abandoned/unproductive hatcheries which would then serve as milkfish satellite hatcheries once rehabilitation is completed.

This paper reports the first use of thin flakes (310–315 μm thick) formulated diets as feed for the abalone Haliotis asinina. The study compared noodles and flakes prepared using refined and unrefined diets developed earlier for H. asinina (Bautista-Teruel et al., J. Shellfish Res., 35, 2016, 633). Four treatment diets in triplicates (refined flakes, MBTr-F; refined noodles, MBTr-N; unrefined flakes, MBTur-F; and unrefined noodles, MBTur-N) were used in a feeding experiment conducted in a tank facility. After three months, abalone fed MBTr-F had significantly higher mean shell length and body weight (35.92 ± 0.36 mm, 9.24 ± 0.29 g) compared with those fed MBTr-N (34.63 ± 0.37 mm, 8.22 ± 0.28 g) and MBTur-N (34.23 ± 0.36 mm, 7.66 ± 0.26 g), but did not significantly differ with those fed MBTur-F (35.40 ± 0.30 mm, 8.57 ± 0.24 g). Likewise, abalone fed MBTr-F had significantly higher mean growth rates (5.31 ± 0.08 mm, 2.59 ± 0.06 g/month), compared with those fed MBTr-N (4.90 ± 0.19 mm, 2.26 ± 0.12 g/month) and MBTur-N (4.71 ± 0.02 mm, 2.07 ± 0.06 g/month), but did not significantly differ with those fed MBTur-F (5.11 ± 0.06 mm, 2.37 ± 0.04 g/month). Survival (96.67–98.89%) and FCR (2.2–2.5) did not significantly differ among treatment diets. Between the flaked diets, MBTur-F is the cheaper option. However, the use of this unrefined diet resulted in distinct turquoise abalone shell colour, not observed in those fed MBTr-F.

Background: The fishery and aquaculture of the widely distributed mangrove crab Scylla serrata is a steadily growing, high-value, global industry. Climate change poses a risk to this industry as temperature elevations are expected to threaten the mangrove crab habitat and the supply of mangrove crab juveniles from the wild. It is therefore important to understand the genomic and molecular basis of how mangrove crab populations from sites with different climate profiles respond to heat stress. Towards this, we performed RNA-seq on the gill tissue of S. serrata individuals sampled from 3 sites (Cagayan, Bicol, and Bataan) in the Philippines, under normal and heat-stressed conditions. To compare the transcriptome expression profiles, we designed a 2-factor generalized linear model containing interaction terms, which allowed us to simultaneously analyze within-site response to heat-stress and across-site differences in the response. Results: We present the first ever transcriptome assembly of S. serrata obtained from a data set containing 66 Gbases of cleaned RNA-seq reads. With lowly-expressed and short contigs excluded, the assembly contains roughly 17,000 genes with an N50 length of 2,366 bp. Our assembly contains many almost full-length transcripts – 5229 shrimp and 3049 fruit fly proteins have alignments that cover >80% of their sequence lengths to a contig. Differential expression analysis found population-specific differences in heat-stress response. Within-site analysis of heat-stress response showed 177, 755, and 221 differentially expressed (DE) genes in the Cagayan, Bataan, and Bicol group, respectively. Across-site analysis showed that between Cagayan and Bataan, there were 389 genes associated with 48 signaling and stress-response pathways, for which there was an effect of site in the response to heat; and between Cagayan and Bicol, there were 101 such genes affecting 8 pathways. Conclusion: In light of previous work on climate profiling and on population genetics of marine species in the Philippines, our findings suggest that the variation in thermal response among populations might be derived from acclimatory plasticity due to pre-exposure to extreme temperature variations or from population structure shaped by connectivity which leads to adaptive genetic differences among populations.

Tilapia is a very promising aquaculture species with the development of the aquaculture industry. The commercial value of tilapia varies greatly with size in certain countries like Israel and Africa. In Southeast Asia, size is not an important factor; the market price varies regionally. Although tilapia could compare favorably with other aquaculture products, its flesh being very high in quality, some consumers have a strong objection to its dark skin. Nonetheless, tilapia is currently one of the most important fish crops in most countries of the world. With the improvement of aquaculture technology, tilapia is now grown in fish cages, fishponds and other inland waters. There is no doubt that this has helped increase the production of the aquaculture sector to the total fish production by over 20% in 1983. The 1984 production of tilapia in fish cages was 7,070 kg; for inland fisheries, the production was 22,295 kg; and in fishponds, 10,508 kg. This gave a total value of P485,653 (BFAR Statistics 1981). With appropriate processing technology, tilapia can be manufactured into various products both for human consumption and as feed ingredients which will help increase its commercial value. Tilapia which are too small for human consumption should not be wasted. These can be converted into feed ingredients for livestock feeds or used as baits in commercial fishing. In developing countries like the Philippines where there is an immediate need for protein source, tilapia could be readily available due to subsistence and commercial-scale culture of this fish.