Alarm bells are ringing about the unscientific ways of harvesting wildlife including fish and plants. According to a new study by evolutionary biologist Chris Darimont of the University of Victoria in Canada, and colleagues, the rate at which hunted and harvested species are changing their size and breeding schedules is cause for concern. Rapid changes have been noted in heavily exploited fish and other species since the 1970s. For example Atlantic cod (Gadus morhua) have decreased 20% in size over the past 30 years, and females now reproduce a year earlier than they used to. The studies included 29 species, mostly fish but also a few invertebrates, mammals, and plants. The team compared these studies with two databases: one for species such as Galápagos finches that had changed through natural selection and one for nonhunted species exposed to other human influences such as pollution. Exploited species transformed on average three times faster than those in natural systems and 50% faster than species subject to other human interference and were shrinking, breeding earlier, or both.
The practice of taking a large percentage of the prey population and targeting the largest individuals favors small individuals, which in turn breed before reaching exploitable size. Smaller sizes and altered breeding schedules could decrease species' abundance, and severely affect their ability to recover from exploitation. Interactions with predators and competitors also get upset.
Man’s avarice is tipping the apple cart of nature’s food web. Animals and plants are getting affected. Time to put a brake to this senseless carnage and act is now. It is not too late to start the ameliorative process.
Full report can be accessed online in the Proceedings of the National Academy of Sciences.
No comments:
Post a Comment