Western Yew is listed as "Near Threatened" by IUCN because of threats and declines. Threats include logging and harvesting of the bark for Paclitaxel, a compound that was found to be successful in the treatment of several cancers including ovarian and breast. At least this had been a threat. It was estimated that one tree was being killed for every patient treated and it was clear that this was not going to be sustainable! Two Cornell postdoctoral researchers got on this problem in the early 1990's and were successful in developing a process to produce Paclitaxel from plant cell cultures through fermentation. Large scale production meant that this natural product could be available at a fraction of the cost and effort and the yew trees were saved! Yay!
Western (or Pacific) Yew on the coast often grows with many short branches and twisted stems. In the 1990s it was discovered that this is because a mite the Big Yew Bud Mite, (Cecidophyopsis psilaspis) damages the buds at the ends of branches by feeding on them. A team of scientists from the Pacific Forestry Centre looked at the prevalence of this mite in B.C. and found that except for a few high elevation sites, all the coastal locations searched had the mite, and the interior ones did not (http://cfs.nrcan.gc.ca/publications?id=32959). They also concluded that the mite was likely not native and was introduced from Europe on English Yew (Taxus baccata). It turns out the “characteristic” shape of a coastal yew isn’t the way the yew used to grow and likely is only recent. This would explain why the bows, tools and paddles that were made from Western Yew by the coastal first nations were straight and true.