What is a 'Blubber Biopsy Sample'?

    The blubber biopsy sampling technique is a recently developed method for obtaining skin and blubber samples from live, 'free-ranging' whales. In many studies, this technique can replace the older method of gathering samples from the carcasses of beached whales--thus sampling is more effective, performed with greater accuracy (as contaminants and the tissues of the animal breakdown in various ways, after death), and at much greater convenience to the researcher (making studies more cost effective, and easier to perform on a sustained basis).

    Unfortunately the age of a whale cannot be determined from a blubber sample. The age information is very important, as we discussed earlier, because PCBs and other lipophillic contaminants are accumulated throughout the entire life-span--therefore, we would expect older males to be most contaminanted, and reproducing females to be the least contaminated.

    Sex on the other hand, can be determined in the lab through karyotyping done with blubber biopsies. The lack of age information is nearly the only significant disadvantage to this technique.

How is a Blubber Biopsy Taken?

Richard Sears of the MICS, holding a modified crossbow for taking biopsy samples.

    Biopsy samples are simply very small cores of skin and the underlying blubber. Samples are obtained from a whale using a modified gun or crossbow to shoot a "punch-type" biopsy dart into the side of the animal. After the initial puncture (which it would appear, most whales do not evem notice), the dart 'falls out' of the whale and is kept afloat by a buoyant end.

    The researcher can then easily retrieve the sample, and record relevant data concerning geographic location, the site on the whale's body from where the sample originated, etc. Research has demonstrated that biopsy samples of outer blubber layers are good indicators of overall PCB and OC contamination in the blubber of baleen whales. Studies of a both theoretical and experimental nature suggest that contaminants such as PCBs reach equal levels throughout the various blubber layers in a relatively short period of time.

    The St. Lawrence River is perhaps the most important commercial artery in North America. It provides the main shipping link to major centres around the Great Lakes such as Detroit, Chicago, Toronto and Montreal. Being the hub of much economic activity, the banks of the Great Lakes and St. Lawrence have attracted large amounts of industry at an increasingly rapid rate since WWII.

    The St. Lawrence (river and gulf) is also a very rich ecosystem, containing 185 species of fish, 20 species of marine mammals, 100 species of birds (not including those that stop over during migration) and more than 1300 species of plants. Unfortunately industrial development around the Great Lakes and St. Lawrence has caused great environmental disturbance to these diverse habitats. Deformed fish, endangered whale populations and toxic spills are seemingly commonplace.

    Because organisms such as marine mammals accumulate contaminants over a long time period, they can be considered sentinels for the health of the ecosystem; coupled with computer models of predicted contaminant accumulation patterns, PCB levels in whales for example, can be used to estimate the amounts of PCBs in the total immediate environment.

    Whales that only summer in the St. Lawrence, feeding almost exclusively in this area, can be particularily interesting subjects when examining the overall health of the environment. Because the vast majority of their food intake is from low-trophic level invertebrates, food-chain effects known as biomagnification, account for nearly all of their contaminant burden.

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by Geoff Wild and
Jason de Koning