February 3, 2009

Fish and Health

Are the fish we catch safe to eat?

by Bob Hetzler

The answer depends on where the fish is caught and how much or often you eat fish. We have read about the pollution from DDT released in the LA area some forty years ago. Yes, the DDT is slowly dissipating in the water and thus levels of DDT are reduced in the food chain. One measurement of this dissipation is that the Catalina eagles have finally hatched one of their eggs. This is significant because in the past, DDT levels have made the eagles’ eggs too fragile to hatch without breaking in the process.
Based on recent reports, the level of DDT in locally caught fish is reduced but still there. Therefore, the recommendation is to eat the locally caught fish not more than once a week. Pregnant women should not eat it more than once a month.

Over the past few months, there has been a significant increase in marine animal deaths in coastal waters between San Pedro and San Diego. The deaths include seals, coastal birds, dolphins and whales. A toxin called Domoic Acid, produced from a bloom of special algae, causes death. As a result of an unusually high level of this toxin, the State Department of Health Services issued warnings about eating locally caught seafood. The toxin affects the nervous system of the animals resulting in high level of mortalities. Out of about 150 affected birds, only fifteen survive. Similar levels of seals have also died.

The bloom of the domoic acid algae is most likely a result of an increase in Santa Ana offshore winds, which cause an up welling of cool nutrient rich water. Add increasing sunlight and the conditions become perfect of the algae growth. Bait fish eat the algae and condense the toxin, larger fish eat the bait further condensing the toxin to lethal levels. The offshore areas generally do not support the growth of this type of algae. Therefore, offshore caught fish should be safe to eat.

The condition that supports the bloom of the toxin algae also supports the algae that causes red tide. Red tide has suddenly appeared at levels not seen in a number of years. The only good thing is that the red tide may replace the toxic algae. Red tide is not poisonous to the marine mammals but can cause large fish kills in enclosed bays by using up the oxygen in the water. Red tide is poisonous to humans when eating clams and mussels. This is the reason why claims and mussels are not permitted to be caught during the summer months.

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