Wednesday, July 11, 2012

Pesticides in Long Island Sound Lobsters. What Does It Mean?

Tiny amounts of pesticides have been found in a handful of lobsters caught in Long Island Sound and tested by the Connecticut DEEP and UConn. You can read a good account of it in the Ct Mirror, here.

It is an interesting finding, but it’s also perplexing. Researchers will now look for a cause and effect link between pesticides and the 1999 lobster die-off in Long Island Sound. But it’s not clear to me how this discovery in 2012 will lead to any conclusions about something that happened 13 years ago.

To review: There was an enormous die-off of lobsters in the Sound in 1999. The die-off coincided with the spraying of pesticides to kill mosquitoes during a West Nile outbreak. It also coincided with a period of warming water temperatures in the Sound. And it coincided with a peak in the Sound’s commercial lobster catch.

The warmer water is significant because the American lobster, Homarus americanus, is a cold-water species, and Long Island Sound is at the extreme southern end of its inshore range. In other words, before the Sound’s water started warming, water temperatures in the Sound were about as warm as lobsters could tolerate anyway.

So by the late 1990s, there were millions of lobsters living in conditions that were unsuitable for them. The Sound’s lobster population was stressed by a change in habitat conditions.

The peak in the commercial catch is interesting because throughout the 1980s and 1990s, Long Island Sound – particularly the western half – was essentially a lobster ranch. Lobstermen would consistently pull traps crammed with 20 lobsters feeding on bait; typically 19 of those lobsters were too small to be kept legally. So the lobstermen would throw them back. The small lobsters would then enter more traps and continue to feed on the bait, and so on until the lobsters were big enough to keep.

In other words the lobstermen were essentially ranching or farming lobsters, feeding them on bait in cages, and spurring the growth in population. Overpopulation was another source of stress. (That, by the way, is not just my opinion; it was the conclusion of the Connecticut DEEP and the New York State DEC.)

Scientists concluded a decade ago that water temperature and overpopulation were among a few environmental stresses that led to the die-off by making the lobsters vulnerable to a parasite that killed them.

Now maybe pesticides should be added to that list. Or not.

The recent tests that detected the presence of pesticides in Sound lobsters are far more sensitive than previous tests. They were able to find concentrations of pesticides that were too small to be detected 10 years ago.

The tests of course don’t answer the question of whether the pesticides were there in 1999. Also still to be determined is whether the tiny amounts detected are enough to do any damage to the lobsters. It’s also unknown whether pesticides will show up in a new batch of lobsters being tested now.

And it’s important to remember that the new tests are from this year. The lobsters die-off happened in 1999. And once they died, they stayed dead – the population has not rebounded.

So if the lobster population died off in 1999, what is the significance of pesticides found in Long Island Sound lobsters in 2012?

Again, the presence of pesticides in Long Island Sound lobsters is an interesting finding. But for now al it means is that pesticides were found in a few lobsters. It does not mean – yet – that pesticides are hurting the lobsters. Nor does it mean – yet – that pesticides caused the lobster die-off in 1999. Further tests may answer those questions.

Does it sound as if I am trying to rationalize or excuse the use of pesticides? I’m not. You can read just about everything I’ve written on this blog about pesticides and lobsters here. We as a society use way, way too many pesticides. I’m for banning or severely limiting their use.

But the more important reality may be that there are no longer a significant number of lobsters in the Sound because the habitat has changed and Long Island Sound simply is no longer lobster habitat.

The DEEP's press release about it is here, although you'll notice that they bury the pesticide finding in the 13th paragraph.


Anonymous Anonymous said...

What about the fact that in 1999-2001, more than just a few lobsters displayed visible signs of shell rot?

How do we know they died off and did not simply relocate once conditions became less tolerable? Why did landings increase outside of the Sound on both the eastern and western ends?

6:38 PM  

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