OLYMPUS DIGITAL CAMERA
Aquashade installed in a tilapia breeding pond. Seed was produced in both pond-based and hapa-based production systems
A state university in the Philippines has implemented a no-frills technology to address the effect of rising water temperatures associated with global warming in open-air mud-dike tilapia hatchery ponds.
Aquashade, which is made of netting materials and a metal frame, decreases the temperature in shaded ponds and positively impacts the reproduction and spawning rate of tilapia. It is especially helpful during the summer months of March to June, when temperatures in the country hit over 36°C.
“One problem for the tilapia seed production industry in the Philippines is the effect of very high temperatures during summer, leading to very low or no seed production,” said Dr. Emmanuel Vera Cruz, who developed the technology. “For tilapia, the best temperature for reproduction is between 28 to 32 ºC.”
Vera Cruz is dean of the College of Fisheries and concurrent director of the Freshwater Aquaculture Center at the Central Luzon State University (CLSU) in the province of Nueva Ecija.
“Aquashade makes use of netting materials installed on top of ponds and serves as protection against excess sunlight during tilapia breeding,” he added. “It reduces water temperature to make it favorable for reproduction, improves the oxygen holding capacity of the water, reduces the fluctuation of water temperature and increases the economic benefits of increasing fry production especially during summer months.”
He explained that shading the breeding area during summer reduced the mean water temperature by around 3 to 4°C during the hottest period of the day. This results in increased spawning rates and increased seed production compared to those of breeders stocked in unshaded ponds.
Tilapia is one of the dominant species in Philippine aquaculture, but there has been a consistent drop in annual production, based on data released by the Philippine Statistics Authority.
The factors cited for the drop on the year-on-year figures were high mortality rates, high weather temperatures, and fewer stocking opportunities.
- Ruby Gonzalez