BAR TODAY || Official Quarterly Publication of the Bureau of Agricultural Research

Transgenic fish 21st century solution to decreased fish farming productivity
by Saturnina Halos

July-September 2000
Volume 2 No. 3

Fish, seaweed and shellfish farming are traditional practices in the Philippines. Farming bangus, oyster and tahong cultures are probably the older practices as compared to tilapia farming which was introduced only in the 1950s, and prawn and seaweed farming in the late-1970s. Farming other fish and shellfish started only recently. Fish farming or aquaculture needs to grow in order to feed a rapidly growing population. And the continuing decrease in fish catches from both fresh and saltwater sources makes this need all the more urgent. This concern is felt not only in the Philippines but in the whole world. In the US alone, aquaculture production has grown 5-10% annually in the past decade. From 1984 to1998, global aquaculture production more than doubled. The UN said world aquaculture production must increase seven times in the next 25 to 30 years just to maintain current levels of consumption.

Fish farming, however, faces many challenges. To wit, the increasing cost of feeds, pest and diseases, and pollution. All these had an impact on the Philippine prawn industry. In the early 1980s, the industry grew to a thousand farmers. Now, it has dwindled to only a handful of farmers.

Science offers a solution. The perfect fish - resistant to disease, fast-growing, great-tasting and easy to raise - is being developed through genetic engineering or the transfer of specific, desirable genes by hybridization. In fact, a fast-growing transgenic Atlantic salmon is now ready for commercialization. Other species like tilapia, bass, rainbow trout, etc. will be made available soon.

The fast-growing transgenic Atlantic salmon has received a gene construct that increases the amount of growth hormone produced by the fish. The gene construct is comprised of a DNA sequence, which is obtained from an edible Arctic fish, and a growth hormone gene of the Atlantic salmon. The gene construct is expressed in the liver and in the brain, thereby producing more of the growth hormone. In an ordinary fish, the growth hormone is produced only in the brain, hence only a small amount of the hormone is produced. The increased growth hormone has allowed the transgenic fish to mature within 14-18 months compared to the three-year cycle of the ordinary Atlantic salmon. According to the US-based AF Protein, the company that developed the transgenic fish, the taste is the same as the wild varieties and looks essentially the same as those caught in the wild. There are no clear health risks associated with the transferred genes since these are obtained from edible fish. Farmers and consumers alike are both projected to gain much from this. A farmer may see increased profits due to a reduced feed requirement and faster turnaround time, while the consumer pay less for the product. Genetic engineering is expected to usher in a new era in aquaculture, which proponents call the "Blue Revolution" - the solution to feeding an increasing population and saving the seas and waters from overfishing.

Critics like Greenpeace and similar groups predict that the introduction of transgenic fish will prompt a disaster. They believe transgenic fish which escape from fish farms will out-compete the native variety in the wild or that a transgenic fish-native species hybrid would produce weak offsprings - only those who have the transferred gene will survive. In either case, biodiversity will be reduced. Biodiversity is important, as it is the source of desirable genes. The fast-growing transgenic fish would not be possible without the Arctic fish, after all. This scenario happened with the native "hito" in the Philippines. When the Bangkok "hito" was introduced in Southern Tagalog, the native "hito" became rare. But one prediction in the 1950s - that of tilapia becoming a pest or killing other native fishes - has not come true. Proponents of the "Blue revolution" are improving further on the transgenic fish. To prevent the spread of the transferred gene into wild fish populations, they are engineering the transgenic fish to be sterile, rendering it incapable of hybridization. Other desirable genes are being transferred such as resistance to disease, tolerance to cold and improved flesh quality.

The National Biotechnology Research and Development Program which is coordinated by the Bureau of Agricultural Research has approved the implementation of a project on transgenic tilapia proposed by Dr. Cynthia Saloma from the National Institute of Molecular Biology & Biotechnology, UP Diliman. With the increasing problems borne of fish kill and pollution in bangus farms, the BAR is inviting study proposals on developing transgenic bangus as well.

(For more information, contact Dr. Halos at the Bureau of Agricultural Research or call at telephone numbers 920-0226; 9288624 loc 162)