A Bad Season for Northwest Marine Life

I’ve taken the stance that if we want to have the nutritional benefits of fish such as salmon, without pollutant exposures or introductions of exotic species, we should try to develop sustainable ways of farming fish. While the following story is more about sea birds, it has implications for other species feeding high on the ocean foodchain.

From BoingBoing, I was alerted to a story about elevated findings of dead birds observed during recent coastal surveys. A suspected cause reported in the Seattle Times is warming of the ocean “apparently caused by a lack of upwelling” that also brings up cold, nutrient-rich deep water that feeds the marine foodchain. (BoingBoing is less circumspect, stating that “[f]or reasons that mystify scientists, ocean temperatures are rising, which is killing off the plankton. As a result, animals higher on the food chain are facing mass starvation.”)

I don’t think either rendition gets the story entirely right – actually, what is thought to be the case is that warming of the ocean from climate changes promotes stratification in the water column, suppressing upwelling. While increased surface winds can mitigate this effect, if the winds aren’t sufficient, then the upwelling doesn’t occur. This stratification has coincided with poor habitat for Pacific Northwest salmon, herring, anchovies and smelt, which I suppose would eventually have an impact on the bird populations

None of the stories about this event have shown the data, so here they are. What seems to have sparked all of the interest is the data from the second quarter of 2005, which show a noticeable increase in the number of dead birds across all of the beaches surveyed.

From the perspective of this blog, the birds are just a symptom – this occurrence represents another reason why it might not be the best idea to rely on wild fish to meet dietary needs. Recall that fish consumption is recommended to maintain adequate intake of omega-3-fatty acids that promote cardiac health. However, fish consumption, particularly farmed fish, contributes to exposure to persistent organic pollutants such as dioxins. Consumption of wild fish is associated with lower dioxin exposures, and the recommendation has been made that people favor consumption of wild fish. However, speaking for salmon, with all of the existing pressures (streamflow modifications from dams and agricultural water use, habitat loss, climate change impacts) maybe reducing fishing pressure would be a good idea to assist recovery of natural populations. More information on climate change and impacts to PNW salmon populations can be found in the proceedings of this recent symposium.

Fish farming has its problems, but are those solvable through application of best practices? More on that later.