Rotting Fish: More Food for Thought

• Cause of fishkills. Although the specific cause of fishkills is unknown, they are more likely to occur on areas where fish farming activities are excessive and water pollution from industrial, domestic and agricultural wastes infest lakes and coastal waters. Dissolved nutrients trigger phytoplankton or algal blooms and subsequent decay. This decay may transfer to other areas or settle at the bottom, to be brought up later by upwelling.
• Tolerance level of organisms. Most water organisms can tolerate pollution. However, this tolerance is limited and differs among organisms.
• Effect of various levels of water pollution. Low levels of pollution may prevent organisms from reproducing, but may still allow them to grow. A higher pollution level may restrict growth, but may still allow survival. At the limit of pollution tolerance, fishkills may be triggered.
• Impact of unregulated aquaculture.  Unregulated aquaculture practices have produced conflicts of interest, which in turn caused ecological, social, economic and political problems.

Example: Laguna Lake Development Authority (LLDA) fish pen culture, 38-hectare pilot project (1970-1980’s)

o   Ecological problem. The uncontrolled growth of the fish pen industry polluted the open waters with excess feed and fish feces.

o   Social dilemma. A few hundred rich fish pen operators from prominent families controlled and dominated the industry. This practice robbed poor fisherfolk of their fishing areas and navigation lanes.

o   Political conflict. The LLDA reported that an elite group of fish pen operators owned up to over 4,000 hectares of fish pens, even though the law clearly states that no entity can own more than 50 hectares of fish pen concessions. The LLDA also found out that politicians and ranking military officers owned some of the other huge fish pens.

o   Economic predicament. The fish pen industry competed for the lake’s budget of natural food. It polluted the waters, which reduced the fish catch of poor fisherfolk. It also ruined the water resource, which not only supports fisheries, but also water supply, irrigation, and navigation.

Source:

Lacanilao, Flor, “Rotting fish: More food for thought.” Philippine Daily Inquirer, page A17, 20 June 2011.