Saturday, July 16, 2005

Scientists Think New England's Lobsters Might be on the Verge of a Big Die-Off

Some scientists think conditions are right for a catastrophic lobster die-off elsewhere in New England, like the one that hit Long Island Sound in 1999.

Lobster scientists met in Rhode Island the other day for a symposium and the Providence Journal reported that rose-colored glasses weren't exactly in evidence.

The star of the show was J. Stanley Cobb, a retired biological sciences professor at the University of Rhode Island, co-author of a standard lobster text and a mentor to many of those at the symposium.

Peter Lord, ProJo's environment reporter, wrote:

Cobb, in a presentation, said he is concerned about the effects on lobsters of rising water temperataures and pollutants in bottom sediments.

"It makes one wonder whether the net result is a lower threshold to disease. It's a real concern. And I don't have a clue what to do. A new disease would change natural mortality rates, and impact what fishermen can take out of the population. So to me, that's a real challenge to lobster biologists. The emergence of disease is an important population leveling factor."

Lord then went on to quote a lobster biologist named Jan Factor (who coincidentally was my roommate for a while back in '83 and '84, when he was first teaching at SUNY Purchase and I was starting as a reporter):

Jan Factor, a biologist at State University of New York, offered a way of looking at what is happening to lobsters, based on his observations following the dramatic die-off of lobsters in western Long Island Sound in 1999.

First there is an environmental stress. In the Sound it was water temperatures rising to levels lethal to lobsters. Also, dissolved oxygen in the water declined dramatically.

The stresses caused physiological problems for the lobsters that weakened their immune systems. That allowed a breakout of disease. In the Sound, it was shell disease and a parasitic amoeba. The result was dramatic mortalities.

"The same things won't happen everywhere," Factor said. "But fill in your own stresses, upsets and diseases. We can generalize from the experience in Long Island Sound, which was a very extreme experience."

Lobster population, and the role of lobstermen in raising the population to what might be artificially high levels, is also important. Here's what I wrote in my book:

In the Sound, lobsters are almost like livestock being raised for slaughter. A lobsterman on the Sound can haul a trap crammed with up to twenty undersized lobsters for every keeper. These "shorts" have gorged themselves on the bait, and since the lobsterman must by law toss them back, he is, in effect, feeding lobsters now so they will be big enough to keep later.

Here's what Lord reported:

In Maine, lobster catches continue at high levels. But the scientists pointed out that lobster populations have increased in direct proportion to the decline of cod, a key predator. Also, with 3 million lobster pots in the water, Maine fishermen are simply feeding young lobsters.

The lobster die-offs and diseases aren't inconsequential and they're not isolated. Lord summarized the sentiment at the symposium: These are "problems that seem to be changing entire ecosystems."

(Thanks to Sandy Pardes of the Connecticut Fishing and Connecticut Fishing Report blogs for the heads up on this story.)


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