Wednesday, June 8, 2011

Rotting fish: another food for thought

By Flor Lacanilao

Most of the fish kills in the country are in lakes and coastal waters where excessive fish farming in cages or pens are located. A common cause is pollution build-up from industrial & domestic wastes, agricultural fertilizers & pesticides, and culture-fish feces & excess feeds. These excess dissolved nutrients can trigger phytoplankton or algal blooms and subsequent decay, further causing degraded water condition (e.g., toxic or oxygen deficient) that may cause fish diseases and subsequent death or fish death directly. This brief is excerpted from 1986 and 1987 reports (see Notes below).

The Laguna Lake show how unregulated practice of aquaculture has given rise to conflict of interest, which caused serious ecological, social, economic, and political problems. Let me tell a story on Laguna Lake frequented by fish diseases and deaths in the 1980s. 

Way back in 1961-1964, when there were no fishpens, the annual catch of small fishers in the Lake was 80,000-82,000 tons. In 1968, a survey showed that some 8,000 full-time and 2,000 part-time fishers used the Lake as a communal fishing ground. For shrimps and molluscs, it was about 240,000 tons. The bulk of this catch was used for animal feeds, mainly by the duck-raising industry.

There were 23 species of fish caught in Laguna Lake, with the goby (biyang puti) and perch (ayungin) as the dominant species. Carp, catfishes (hito and kanduli), snakehead (dalag) and tilapia were also caught in the lake in addition to migratory species from Manila Bay, which came via the backflow of the once unpolluted Pasig River.

In 1971, the Laguna Lake Development Authority (LLDA) introduced fishpen culture with a 38-hectare pilot project at Looc in Central Bay. Milkfish (bangus) was chosen because of its market value, and it feeds directly on phytoplankton, which was abundant in the lake. The project gave encouraging results, like producing 3.5 times more fish per hectare over that in open waters. “The lake fish pen aquaculture has been estimated to have a potential for expansion to 20,000 ha of fish pens having an annual production value of 320 million pesos.” This prompted businessmen and entrepreneurs to go into fishpen culture. Development expanded to 4,800 hectares by the end of 1973; the gross annual value of production in 1973 was P76.8 million.

Data in 1982 showed that fishpens, then 31,000-hectares, produced 62,000 tons of fish, while the open waters yielded only 19,000 tons for the small fishers – or a total lake harvest of 81,000 tons. This was clearly equivalent to the yearly catch of small fishers in 1961-1964 before the introduction of fishpens.

The excessive growth of the fish culture industry in the Lake later proved counter-productive. The milkfish took more time to grow because of increased competition for natural food, the 4-month rearing time had stretched to 8-15 months. This was corrected with supplemental feeding, which also allowed increasing the fish stock. Meanwhile, the catch of the small fishers dwindled to one-fourth that of their pre-fishpen catch, which was predictable from the start. 

What the fishpens did was rob the small fishers of their traditional catch -- by reducing their fishing areas, competing with phytoplankton that fed the milkfish, polluting the waters, and reducing the fish catch from open waters. Note that the native species depended on the phytoplankton for food directly and indirectly through food chains. Further, water circulates in and out of the fishpens, bringing in food and taking out wastes and excess feed to pollute the open-waters.

The conflict was between the community of poor fisherfolk of more than 15,000 families and the group of a few hundred rich fishpen operators. In a report published in the newspapers, the LLDA identified an elite group of fishpen operators owning 10 of the largest fish pen areas on the lake totalling more than 4,000 hectares (the law says, no person or corporation can own more than 50 hectares of fishpen concessions). The list showed members of prominent families, including politicians and ranking military officers.

The fishpens have also deprived the shrimps and molluscs in the lake of their food budget. This adversely affected the small-scale industries, which use these products and provide livelihood for many lake-shore families. In addition, the fishpens contributed to the deterioration of the lake for water supply and obstructed the navigation lanes.



1. Flor Lacanilao. 1987. Managing Laguna Lake for Small Fishers. SEAFDEC Asian Aquaculture 9(3): 3-4.

2. Jon Davis, Flor Lacanilao, & Alejandro Santiago. 1986. Laguna de Bay: Problems and Options. White Paper No.2, Haribon Foundation.

3. See also “Extensions of ‘The Tragedy of the Commons” by Garrett Hardin. 1998. Science 280:682-683.

(Dr. Flor Lacanilao obtained his Ph.D. (specialization in comparative endocrinology) from the University of California at Berkeley. He served as chairman of the Zoology Department at UP Diliman, chancellor of UP Visayas, and chief of SEAFDEC in Iloilo.) 

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