Pollution of Fish Species Reflects Hazard of Modern Science

The Associated Press reported on February 20, 2004 in a news piece entitled, “Hungry Cod Swallows Coke Can Off Norway,” that a family in Western Norway found a Coca-Cola can inside the stomach of a codfish while they were preparing dinner. The soda can was “slightly dented but intact” [1]. The family was shocked, as they had expected the cod’s stomach to be filled with roe. Instead, it was filled with a soda can.

This was not the first time that the media reported on pollution harming fish in the Arctic or Antarctic. Nature magazine published an article entitled, “Delivery of Pollutants by Spawning Salmon,” in its September 18, 2003 issue reporting on spawning salmon dumping toxic industrial compounds in Alaskan lakes upon their return from the ocean. “Groups of migrating sockeye salmon (Oncorhynchus nerka) can act as bulk-transport vectors of persistent industrial pollutants known as polychlorinated biphenyls (PCBs), which they assimilate from the ocean and then convey over vast distances back to their natal spawning lakes. After spawning, the fish die in the thousands -- delivering their toxic cargo to the lake sediment and increasing its PCB content by more than sevenfold when the density of returning salmon is high” [2]. This research revealed that, when returning sockeye salmon transport contaminants upstream to their nursery Alaskan lakes, the PCBs might affect their offspring and/or predators such as bears, eagles and humans, thus affecting ecology systems far and wide.

It is known that PCBs, a common class of toxic industrial pollutants, are easily and widely distributed over vast distances by the atmosphere and the oceans. This finding has now confirmed that PCBs can also be transported by spawning salmon and amplified through the food chain. “Sockeye salmon spawn in freshwater after spending most of their life in the ocean, and die after spawning” [2]. Moreover, “the amount of PCBs transported by sockeye salmon to these lakes is greater than the traditional assignment from atmosphere pathways.” Scientists never expected that migrating sockeye salmon could act as “biological pumps” by transporting chemical pollutants bioaccumulated in their bodies back to the lakes! [Bioaccumulation refers to the process by which toxic pollutants amass in the tissues of organisms after repeated intake or exposure.]

In the January 9, 2004 issue of Science (Science, 303: 226) magazine, another report points out that “farmed salmon have significantly higher contaminant burdens than wild salmon” [3]. In fact, the concentrations of organochlorine contaminants that pose cancer risks for humans are about ten times higher in farmed salmon than in wild salmon. [Organochlorine refers to any of various hydrocarbon pesticides, such as DDT, that contain chlorine.] The study focuses on the following persistent industrial pollutants, including polychlorinated biphenyls (PCBs), dioxins, toxaphene and dieldrin. The consumption of farmed salmon may result in exposure to a variety of persistent bioaccumulative contaminants with the potential for an elevation in attendant health risks.

Salmon and cod are important sources of protein and omega-3 polyunsaturated fatty acids for the population in North America and Europe. Due to the body’s inability to synthesise omega-3 polyunsaturated fatty acids, it has to look to external sources to maintain physical health.

Even cod and salmon in the Arctic, Antarctic, and deep sea cannot avoid assimilating from the ocean the garbage and chemicals created by modern science and technology that has been developed to provide mankind with comfort, convenience, and efficiency. It follows that fish in coastal waters or freshwaters must bioaccumulate significantly greater loads of persistent industrial pollutants. If such environmentally conscious countries as Norway and Germany cannot protect fish in their territories from pollution, it follows that the concentrations of organochlorine contaminants must be significantly greater in Southeastern Asia and China, where there is a lack of awareness for environmental protection.

Chemicals and artificial products made by modern science and technology may have brought mankind a materially more convenient life, but they are taking an extremely expensive toll on the lives of future generations. Compared with their attendant costs, such modern conveniences become far from worthwhile.

References:

1. The Associated Press: Cod Swallows Coke Can Off Norway
2. E. M. Krummel, R. W. Macdonald, L. E. Kimpe, I. Gregory-Eaves, M. J. Demers, J. P. Smol, B. Finney, J. M. Blais, Nature, 425, 255-256.
3. R. A. Hites, J. A. Foran, D. O. Carpenter, M. C. Hamilton, B. A. Knuth, S. J. Schwager, Science, 303, 226-229.