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Posts Tagged ‘Sargasso Sea’

At the Perth Wildlife Reserve, where Birdgirl and I enjoyed a hike last week, one of their Species at Risk signs concerned the American Eel (Anguilla rostrata). Not being too familiar with these creatures, I looked up more information about them when I got home. While no one would argue that they are cute and cuddly, American Eels are amazing. [This species is not to be confused with the Lamprey Eels or Sea Lamprey (Petromyzon marinus) that have invaded the Great Lakes.] These brownish, elongated fish grow to about a metre in length and weigh up to 1.5 kilograms. You’ll find a good information page about American eels at the Ontario Ministry of Natural Resources site here. Below is a map from that site showing the distribution of American eels.

All of the entire world population of American eels breed in just one place, the Sargasso Sea in the Atlantic Ocean. From there, young eels migrate inland along rivers and lakes and streams and may travel as far as 6000 kilometres. After reaching their freshwater home, the eels then mature for from 10 to 25 years before making the return journey to the Sargasso Sea to spawn. As the eel matures, it passes through a number of stages.

Virtually all of the eels found in Ontario are large, egg-bearing females and it is thought that the Ontario population contributed substantially to reproduction of the global eel population. I say contributed, past-tense. When you look at the following graph, you will see why.

It illustrates very clearly the population crash that has taken place. The decline is well-understood. It is due to a number of factors:
1) Turbines at hydroelectric facilities. In the St. Lawrence River system, 40 per cent of mature eels that pass through turbines are killed.
2) Physical barriers such as dams that block rivers.
3) Overfishing. American eel are killed throughout their global range and during all of their life stages.
4) Deteriorating habitat due to pollution.
5) Habitat loss in marine waters due to the over-harvest of seaweed in the Sargasso Sea.
6) Changing ocean conditions may influence the ability of eel to drift and migrate to and from the Sargasso Sea. Global warming, anyone?
7) An exotic parasite worm that was introduced into American waters.

Given this overwhelming list of challenges, it is a wonder there are any eels left at all. Probably, soon there won’t be. Are strong actions being taken to help the eel? Given that the population graph shows a significant and continuing drop in numbers from 1986, you might think that moving quickly to end all fishing of eels, would have been one of the easiest steps to take. In fact, Ontario waited until 2004, nearly two decades, before cancelling the commercial and recreational fishing of American eels. The Quebec government has reduced but not ended the commercial hunt of eels.

This is yet another example of Barndoor Conservation. Wait until the horse is gone, or in this case every last eel has been caught, before you shut the barn door or ban the hunt. This approach won’t get your horse back. It isn’t helping to protect our threatened wildlife any better.

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