Smaller Fish After Alewife Die-Off

  • Alewife (Alosa pseudoharengus). The fish is not common in Lakes Superior or Erie. (Image courtesy of Wisconsin SeaGrant)

This past year, the size of salmon in some Great Lakes
is getting smaller because their main food source is dying off in some
areas of the lakes. The Great Lakes Radio Consortium’s Lester Graham
reports:

Transcript

This past year, the size of salmon in some Great Lakes is getting smaller because
their main food
source is dying off in some areas of the lakes. The Great Lakes Radio Consortium’s
Lester
Graham reports:


In the 1960’s, fish and game officials introduced Pacific salmon such as chinook,
coho and
steelhead to control the invasive species alewife. That’s a small fish that moved
in from the
Atlantic. The salmon are popular fishing. But since the alewives are not native…
they’re
especially susceptible to quick weather changes. And fisheries managers suspect
competition
with zebra mussels for food also affects alewives. Recently, alewife populations
have crashed in
some places. Jim Dexter is with the Michigan Department of Natural Resources…


“The primary reason that there are not alewives in Lake Huron and you get
fluctuations in Lake
Michigan is related more to the climate. You know, now, zebra mussels are tied into
that, into the
equation at some point but not probably to the affect that the climate is having on
those.”


So, without as many alewives, salmon don’t have as much to eat… and they’re smaller
than usual.
Fisheries managers say the effect is probably temporary.


For the Great Lakes Radio Consortium, this is Lester Graham.

Related Links

A Closer Look at Mercury Hair Test

  • Hair is now a way to test people for mercury levels, as opposed to more invasive tests of blood and urine. (Photo by Anna Miller)

Health officials are experimenting with another way to gauge the level of mercury in people who eat a lot of fish. The only test sample needed is… hair. The Great Lakes Radio Consortium’s Chuck Quirmbach
reports:

Transcript

Health officials are experimenting with another way to gauge the level of mercury in people who eat a lot of fish. The only test sample needed is… hair. The Great Lakes Radio Consortium’s Chuck Quirmbach reports:


Doctors can already test your blood and urine for mercury. Now, as a less invasive technique, some health officials can test the hair near your scalp for the toxic chemical. There’s some debate over the quality of the tests, the lab analyses, and over what a high test reading means. The federal health warning for mercury in hair is one part per million. But that’s for susceptible populations like an unborn fetus.


Jack Spengler is a professor of environmental health at Harvard University. he recently ate a lot of fish and says his hair tested out at 3 parts per million of mercury.


“But I’m not going apoplectic about it because I know if I just watch my consumption, I can moderate that over time… and there’s that safety margin…that I suspect I’d have to be much higher for much longer to really have symptoms. ”

Prolonged high levels of the most toxic form of mercury, methyl mercury can trigger various health problems in adults such as memory loss and cardiovascular damage.


For the Great Lakes Radio Consortium, I’m Chuck Quirmbach.

Related Links