There has been no breakthrough in the mystery of why perhaps millions of small fish have died in the Gulf of Nicoya.
Several groups of scientists were at work Thursday trying to determine what happened. If the cause is pollution in the deaths of these anchovies, the source may be far from where the dead fish washed up.
Most of the fish are littering the beaches and are in the surf at the northeastern part of the gulf. But that is the direction to which the winds and currents would push them.
Consequently the entire gulf is suspect now until the solution is found.
Curiously, the 7 to 8 kilometers of dead fish do not seem to have attracted birds or other scavengers.
Residents of the area are concerned about the growing stench.
Health officials have issued the obvious warning not to eat, buy or angle for fish from the area.
However, the warning was restricted to just that part of the gulf where the carpet of dead fish appeared. Expats also should refrain from eating shellfish until there is an answer from scientists.
If the cause is pollution, the amount of substance injected into the gulf must have been massive because there are estimates that the dead fish might be as much as 30 tons. The fish must have died throughout the gulf. In addition to poisoning, the scientists are looking at the oxygen content of the water and the possibility that a blossoming of algae may have generated toxins.
The use of the fish as fertilizer also is being delayed until scientists conclude that no harmful chemicals are present.