Thorny fish

Yes, the title sounds strange, an example of the kind of inappropriate machine translation that you get on the internet. The Filipino “tinik” can mean plant thorns or fish bones, but you can’t say “binuto ako” when you have a fish bone stuck in your throat.

But I’m not doing a linguistics article today. Thorny is used as well to refer to difficult problems, and that is what we have today with fish. I’m in Baguio for the Luzon regional conference of the National Academy of Science and Technology (NAST). The conference is to focus on Philippine fisheries and other aquatic resources. It has been one of the most informative, and thought-provoking scientific meetings I’ve attended in a long time, with enough materials for several columns. I want to zero in, though, on what I felt was the “thorniest” problem discussed in the conference: to eat or not to eat fish.

I’ll be using fish here in a very broad sense to include shellfish, which in turn includes crustaceans like shrimps and mollusks like clams and oysters. In biological taxonomies or classification systems, shellfish are not considered fish.

The Food and Agriculture Organization reports that we’re the fifth largest producer of fish in the world. Globally, fish consumption averages about 20 kilos per person per year. In the Philippines, it’s 40 kilos per person per year.

Malnutrition among fisherfolk

You would think that with such high consumption, we wouldn’t have a protein deficiency problem. Yet a third of our children are stunted; a study by Imelda Angeles-Agdeppa and her colleagues in two coastal towns (fishing communities) in the Philippines found even higher percentages of stunted children.

I was seated with Dr. Ernesto Domingo, a retired professor of the UP College of Medicine, and Dr. Jaime Montoya, head of the Department of Science and Technology’s Philippine Council for Health Research and Development, and the study of malnutrition in the two coastal towns got us speculating on the possible reasons. Clearly, there’s more to nutrition than quantities.

We suspect fishing communities are not necessarily teeming with fish. Our growing population has meant fisherfolk ending up with lower fish catches. They then tend to sell the “best” fish (quotation marks to be explained later on) keeping morsels for themselves, or even ending up buying canned fish or those horrible new products targeting the poor—sachets of ready-to-eat fish that have a few measly pieces of fish drowning in sauce.

Besides children not getting enough protein, low fish consumption among pregnant and lactating mothers means they get lower omega-3 fatty acids, particularly DHA or docosahexaenoic acid, which is vital for the development of the brain, vision and immune functions in the fetus and young children. Think now of a nation of children stunted not just physically, but mentally.

Paranoia about fish safety

But even as we talk about promoting more fish consumption, we face another problem: How safe are the fish and fish products?

At the end of the first day of the NAST conference, people were talking about how paranoid they had become after listening to the papers. Name the “poison”—metals like mercury, arsenic, pesticides, nerve toxins found in harmful algal blooms or red tide—and it seems we have them in our fish.

Among the harmful metals, mercury (or more specifically, methyl mercury) is the cause for most concern. Mercury poisoning mainly affects the brain and nervous system, leading to tremors, memory losses, blindness. Children are particularly vulnerable, mercury poisoning interfering with nerves and muscle cells. Mercury can also cause birth defects. Mercury poisoning may take time to develop, accumulating in the kidneys.

There’s the irony: If you don’t take fish, then you don’t get DHA for brain development. But if you take too much mercury-contaminated fish, the brain is affected.

The risks for mercury contamination are higher in areas where mercury is used to process gold that has been mined. It is also higher in places close to volcanos. I did find one intriguing study from Costa Rica’s National University, which found high mercury levels in the air around volcanos; but when they tested sediments and fish in lakes near the volcanos, the mercury levels were low. This led them to look into other factors affecting mercury levels in humans, and what they found was that people taking more of ocean fish also had higher levels of mercury.

Again there’s irony here. We tend to think of “unsafe” fish as those coming from dirty rivers, and think the wide open oceans probably produce “cleaner” fish. But it turns out mercury levels are higher in fish that are higher in the food chain.

At the bottom of the food chain are the phytoplankton or single-celled algae which, because they’re so small, will be contaminated only by small amounts of mercury. The contamination increases as you go up the food chain: phytoplankton are eaten by zooplankton and small fish. By the time you get to the large fish, you have “biomagnification,” the levels increasing as you go up the chain, especially out in the ocean.

When it comes to avoiding mercury, the advice is to “think small.” Go for smaller species like sardines and dilis. One of the speakers at the conference showed a chart with mercury levels, and the highest were found in swordfish, shark and tuna. That is why I put “best” in quotation marks earlier, referring to how fisherfolk sell ocean catch in greater demand, but which may have high mercury levels.

Toxicologist Dr. Lynn Panganiban said we should definitely continue to eat fish, but be vigilant about the possible sources of mercury.

There’s a website,, that can help you avoid problematic fish, but it’s based on foreign data. We need more local studies—and local websites—to provide information and advice. A plea from vegetarians: Don’t forget the seaweeds.

(My column today draws from conference presentations by Dr. Vachel Gay Paller, Dr. Maria Lourdes San Diego-McGlone, Ms. Adelina Santos-Borja, Dr. Rico Ancog, Dr. Lynn Panganiban, Dr. Rey Donne Papa, Ms. Josie Platon-Desnacido and Ms. Cecile Leah Bayaga. They come from various universities and fields—medicine and toxicology, marine sciences, nutrition, management—reflecting how thorny problems require solutions from all the sciences.