On the relationship between aquaculture and food security: why does aquaculture contribute more in some developing countries than it does in others?

As much as 78% of fish production is subject to international trade competition. While this may be positive for economic growth, it may be at odds with achieving food security. The purpose of this paper is to review the relationship between aquaculture and food security, focussing on trade and markets in some developing countries that account for more than 90% of aquaculture output. The international trade in fish products largely involves the movement of high value species from developing to developed countries and the opposite in reverse, which can contribute to food security. Countries where food security is not improving tend to rely on small-scale aquaculture production of species that are not desired in the main markets, themselves relying on imported fish to meet domestic demand. This suggests that an aquacultural revolution in these countries may contribute to food security, as well as economic growth.This paper has received funding from the EU 7th Framework Programme Project under grant agreement number 289760

Impact of Daily Thermocycles on Hatching Rhythms, Larval Performance and Sex Differentiation of Zebrafish

In the wild, water temperature cycles daily: it warms up after sunrise, and cools rapidly after sunset. Surprisingly, the impact of such daily thermocycles during the early development of fish remains neglected. We investigated the influence of constant vs daily thermocycles in zebrafish, from embryo development to sexual differentiation, by applying four temperature regimens: two constant (24°C and 28°C) and two daily thermocycles: 28:24°C, TC (thermophase coinciding with daytime, and cryophase coinciding with night-time) and 24:28°C, CT (opposite to TC) in a 12:12 h light:dark cycle (LD). Embryo development was temperature-dependent but enhanced at 28°C and TC. Hatching rhythms were diurnal (around 4 h after lights on), but temperature- and cycle-sensitive, since hatching occurred sooner at 28°C (48 hours post fertilization; hpf) while it was delayed at 24°C (96 hpf). Under TC, hatching occurred at 72 hpf, while under CT hatching displayed two peaks (at 70 hpf and 94 hpf). In constant light (LL) or darkness (DD), hatching rhythms persisted with tau close to 24 h, suggesting a clock-controlled "gating" mechanism. Under 28°C or TC, larvae showed the best performance (high growth and survival, and low malformations). The sex ratio was strongly influenced by temperature, as the proportion of females was higher in CT and TC (79 and 83% respectively), contrasting with 28°C and 24°C, which led to more males (83 and 76%). Ovarian aromatase (cyp19a) expression in females was highest in TC and CT (6.5 and 4.6 fold higher than at 28°C, respectively); while anti-müllerian hormone (amh) expression in males increased in testis at 24°C (3.6 fold higher compared to TC) and particularly at 28°C (14.3 fold increase). Taken together, these findings highlight the key role of environmental cycles during early development, which shaped the daily rhythms in fish embryo and larvae, and ultimately influenced sex differentiation

2010 and beyond: better seeds for sustainable aquatic food production in Asia.

Asia is a major contributor to world aquaculture production. Most Asian countries have maintained their rank in the ten top aquatic food producing nations after developing refined techniques for major commercially important aquaculture species and promoting an increased awareness on the merits of using quality seeds (genetically enhanced or otherwise) as supplied in sufficient quantities. Quality seedstock simply means fit, clean , uniformly-sized seeds which could be eggs, fry, fingerling, juveniles and/or plantlets (for seaweeds) that subsequently express good performance attributes during culture. Beneficial traits refer to good color, shape, growth, efficient feed conversion, high reproduction, tolerance and survival when exposed to stressors (e.g. diseases, poor and/or extreme environmental conditions). Such traits are mostly heritable, hence, quality seeds are usually assumed as produced only by mating stocks perceived or proven to be genetically superior. Some bloodstocks may be genetically mediocre but if bred and manage properly through efficient farm protocols (suitable hatchery, nursery feeding and water management methods), may also produce good quality seeds. Success in the sustainable production of aquatic species for human consumption depends primarily on the availability of seedstock and adoption of optimal husbandry techniques among others. With the intensification of aquaculture systems and the environmental challenges such as those resulting from climate change, it is wise to continue considering both factors -- genetic quality and culture management as equally important in ensuring a steady production of good quality seeds and later, marketable products from aquaculture. Views on what, how and why better quality aquaculture seeds should be produced evolve as times change. To understand these concerns, this paper will cover: (a) the present state of fish seed production in Asia, (b) recent and current seedstock production issues that require attention, and (c) recommendations on how to further enhance aquaculture production in the region in the next decade through better quality seedstock

Seasonal population dynamics of Lepeophtheirus spinifer and Neobenedenia sp. coinfecting snubnose pompano (Trachinotus blochii) breeders in marine cages in the Philippines

Studies on the biology and ecology of sea lice are lacking in tropical regions such as in Southeast Asia where finfish cage farming has grown dramatically in the past decades. This study investigated the seasonal population dynamics of ectoparasites infecting captive snubnose pompano (Trachinotus blochii) breeders in marine cages in the Philippines. The pompano breeders were found to be naturally coinfected with caligid copepod Lepeophtheirus spinifer and capsalid monogenean Neobenedenia sp. These breeders were monitored and examined bimonthly (n = 10 per sampling) from September 2017 to May 2018, covering the warm season and cold season in the Philippines. Our results clearly show that L. spinifer population maintain a 100 % prevalence throughout warm and cold seasons however, mean abundance and intensity increased only during the cold months (early November to early March) and displayed an oscillating trend during this period. Highest mean intensity was recorded in early January (221.4 ± 24.6; temperature = 27.5 ± 0.3 °C; salinity = 34.8 ± 0.3 ppt) while the lowest mean intensity was recorded during the warm months dipping to 12.5 ± 1.9 in early May (temperature = 30.5 ± 0.3 °C; salinity = 30.3 ± 0.3 ppt). The prevalence of adult and pre-adult was high throughout the monitoring period at 70–100 % except at the start of summer (late March to early May) for pre-adult (30–90 %). In comparison, the chalimus stages were only observed during the cold months specifically from early November to late January with prevalence of 40–80 %. The highest mean abundance (3.4 ± 0.7) and mean intensity (4.3 ± 0.6) was in early November which coincided with the first peak of the total L. spinifer population. Neobenedenia sp. occurred year-round with no significant changes in the population mean abundance and mean intensity between warm and cold seasons. This study presents comprehensive information on the seasonal population dynamics of L. spinifer and Neobenedenia sp. in the Philippines, providing valuable insights on the ecology of caligid sea louse which is fundamental in the formulation of control and management strategies of these economically significant ectoparasites.The authors thank the staff of SEAFDEC/AQD Igang Marine Station for assistance during the sample collection. This study was funded by CFOS-UPV and SEAFDEC/AQD

Health management of milkfish Chanos chanos

This monograph provides updated information on diseases of marine and brackishwater cultured milkfish in the Philippines. The information presented here is largely based on the results of a three-year research project on milkfish at the University of the Philippines Visayas funded by the Department of Science and Technology (DOST). The project involved surveillance and monitoring of hatchery, nursery and grow-out operations for occurrence of diseases as well as on disease diagnosis, prevention and control. Previously documented reports in the Philippines and in other documents, both published and unpublished, are also included in this monograph. The diseases are discussed on a culture phase basis, that is, disease problems encountered in hatchery-reared larvae and fry are listed first, followed by diseases observed in fingerlings and juveniles grown in nursery and grow-out culture areas, and adult stages maintained in broodstock facilities. Information regarding the causative agent, diagnostic procedures, and methods of prevention and control for each disease are provided, if available

Production, feeding and storage of Tetraselmis tetrathele paste by electrolytic flocculation

An innovative microalgae harvesting technique using electroflocculation was carried out at different voltage treatments (4, 7, and 9 V) using a fabricated voltage regulator and compared with harvesting by electroflocculation at 12 V using a car battery to efficiently electroflocculate Tetraselmis tetrathele. This study was conducted to determine the ideal voltage settings that could improve the quality of harvested paste in terms of nutritional value and metal contamination for its later use in aquaculture. The use of 7 V achieved low Pb content producing the best harvest biomass (1.4 kg, 87 min) which is comparable to the harvest biomass (1.7 kg, 68 min) using a 12 V car battery. Storage of T. tetrathele paste is best done in a chiller (2 ± 1 °C) rather than a freezer (-20 ± -4 °C) for ease in reactivation and maintaining higher cell viability for later use as a starter in aquaculture. Storage in a chiller allows T. tetrathele paste to be resuspended after six months and used as a starter culture.This study was funded by the Aquaculture Department, Southeast Asian Fisheries Development Center (SEAFDEC/AQD) Study code: Nr-01-Y2018T