Posts Tagged ‘Fisheries’

I like to think of the ocean as Earth’s circulatory system, and on a smaller scale of that metaphor, the capillaries that connect the ocean to humans are transferring pollutants between it and us.

There is now a large body of evidence showing elevated toxicity at every level of the marine food web, from plankton to whales, which is the subject of Stephen Palumbi’s talk. Dr. Palumbi describes isolated findings of high PCB toxicity in dolphin meat, pollution at our beaches, and Marine Protected Areas, but I think this talk misses an opportunity to synthesize these results into a more comprehensive picture.

One of the important features of these toxic chemicals is their inability to be broken down in an organism, so as bigger things eat a huge amount of smaller contaminated things, the bigger organism is accumulating a higher level of the chemical. The largest carnivorous marine animals are showing contamination that is MILLIONS of times higher than their surrounding environment, which was described in a paper on polar bears, as well as several studies on whales and dolphins. The mobility of marine creatures and the food connectivity that happens between ecosystems as a result are efficiently delivering the toxic chemicals from land-based pollution sources to marine life throughout the oceans. I would love to see a study that looked at a gradient of human influence on the marine environment and sampled toxicity of plankton, larger invertebrates, fishes, and reptiles and mammals to verify the global extent of contaminant delivery.

Dr. Palumbi discusses how dolphin milk transfers PCBs to the young, which is causing newborns to die in high numbers (this was quite a weak point in the talk that did not describe ‘natural’ death rates in newborn dolphins). I wonder what kinds of feedback loops would be in place if huge progress was made to reduce pollution tomorrow. How many generations would have to die off before we would see ‘acceptable’ levels of contaminants in large marine animals? How much seafood do WE have to eat before it will take us multiple generations (and by generations I mean unhealthy children) to bring our toxicity levels down to healthy levels? And what are the toxicological effects of these pollutants on our susceptibility to disease, our liver or neurological function? Are industrialized countries poisoning the primary food source of coastal populations everywhere?

This is an important issue that will be getting a lot more attention in the future.

Watch the talk here:

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While I understand the need to appeal to our animal cruelty sensibilities in order to popularize a message, I am hoping this film transcends our emotional response to dying fish and presents the inequity of fish consumption in the world, along with the very simple solution for overfishing. Fish less.

This is an issue I intend to discuss in great detail in future blogs. Until then, watch the trailer and find a screening near you!

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