Tuesday, March 13, 2007

The Wall Street Journal would like to inform you...

... that "Maine is at war" -- over freshwater fishing bait. From the front page of yesterday's paper:
RAGGED LAKE, Maine -- An ice fisherman fishes when it's cold; a fly fisherman fishes when it isn't. An ice fisherman uses fish to catch fish; a fly fisherman uses ersatz insects. Maine ice fishermen are mostly born here; fly fishermen are mostly "from away."

These differences have gotten an airing this winter in a legislative debate about bait. Fly fishermen for "bait control" say live bait fish -- especially non-native ones -- get loose in lakes, glom all the food and drive the native trout out. Ice fishermen for "bait choice" say they must fish with live bait or be driven out, too.
Although the worst violence that war correspondent Barry Newman encounters consists of lame jokes and soft putdowns that fly-fishermen tell about ice fishers, or vice versa:
"Ethically, the fly fishermen don't like ice fishing," said John Whalen, who farms bait in Canaan and has led the ice-fishing outcry. "They view it as consumptive, removing 'resource' from the environment -- fish that they want to be able to catch three or four times in the summer."

...Thom Watson, a Bath Democrat, sponsored the other bait bill. He was born in Louisiana.

"My dad was a duck hunter," said Mr. Watson. "He used to say ice fishing was like a hunter sitting by a fireplace looking up the chimney waiting for a bird to fly over."
Newman is clearly fond of the irony that "non-native" fishermen are advocating for laws that regulate non-native fish: he cites the out-of-state pedigrees of the bill's sponsors and supporters, and even mentions that one bait prohibitionist was on his way to a "Thai dinner" after closing his fly shop for the evening (a subtle accusation of elitism, I suppose: "If the ice fishermen are starving, let them eat Pad Siew!")

Funny stuff, but in reality, there are probably at least as many native Maine fly anglers as there are out-of-state ice fishermen. If howling at "out-of-staters" is how the ice fishermen are going to respond to these proposed regulations, they're going to lose, and also foment a lot of useless resentment on the way.

The ice-fishermen argue that bait fish that have inhabited our lakes and ponds for decades are essentially native: "How long do they have to be here before they're called native?" asked Norman Chick, a retired apple grower. They might have come "from away" originally, but they're useful and they've lived here for years without doing much harm.

The man seems oblivious to the fact that his defense of bait might also apply to the legislators proposing the new regulations. But that doesn't invalidate the argument: in fact, a legislative committee had to weaken the bill when they discovered that no one could figure out when or how the allegedly invasive shiners arrived in Maine.

Which reminds me of Alan Burdick's book Out of Eden: An Odyssey of Ecological Invasion. The book mentions that there are hundreds more known alien species in the ocean along the west coast than there are on east coast, in spite of the fact that the Atlantic coast has been exposed to alien species from foreign trade for centuries longer. It's not that the east coast somehow repels invasives. Everything that marine biologists know about the Atlantic coast is based on an ecosystem that has already assimilated hundreds of new species since colonial times: we just can't tell what's "alien" from what's "native" anymore.

Truly, some invasive species pose big problems when they're suddenly introduced into a new habitat (look at what happened when Mr. Chick and Mr. Watson's ancestors met the first native Mainers). But a lot of non-natives arrive in new places without causing catastrophes, and sometimes, they can increase an ecosystem's diversity and resilience. Fly-fishermen should keep this in mind before they anguish too much over bait fish, and ice-fishermen can do likewise before they deride their neighbors "from away."


Anonymous said...

Well, you're half right. A lot of non-native species do arrive in new places without causing catastrophes. And they can sometimes increase an ecosystem's diversity -- if by diversity you mean strictly the number of different species in a particular region. (Ecologists call that "alpha diversity.) But if Maine's waters become more "diverse" due to additions from, say, California, and California's waters become more "diverse" with additions from Maine, now you've got two ecosystems that are "diverse" in exactly the same way, which is the opposite of diversity. These newly "diverse" ecosystems may look new and exciting to the folks in Maine, or in California, but to a person who's seen both places, the overall difference between ecosystems is diminished. That kind of diversity (so-called "beta diversity") is what's really at stake in the non-natives issue, because beta diversity is only going down, not up. It's fun to draw comparisons between the diversity of people and the diversity in nature, as the WSJ reporter did, but in terms of what's at stake, they're two different kettles of fish.

And in no case does adding non-natives make an ecosystem more resilient. It's a popular notion, not really supported by the science. Not even sure what it means -- more resilient to what?

C Neal said...
This comment has been removed by the author.
C Neal said...

Thanks for adding the important beta/alpha distinction. And I'll admit that I know little about how these shiners might affect freshwater ecosystems in Maine - but given the facts that they've been here for decades, and biologists have been unable to discern the details of their "invasion," I won't lose much sleep over them.

Non-native species have been invading new ecosystems since the dawn of life on earth, and historically, it has increased both kinds of biodiversity in the long run. And increased biodiversity makes ecosystems more resilient to disturbances (which could be anything from forest fires to climate change to other invasive species) by increasing the range of adaptive responses that life can use to survive in changed environments.

Now, there are plenty of cases where the accellerated pace of invasion in our global economy has caused ecological catastrophe - one cause among many of diminished beta diversity.

But sometimes, the "long run" between invasion and new evolutionary responses in an ecosystem isn't as long as we might expect: here in Maine, for example, the native blue mussel evolved a thicker shell to protect itself against the invasive Asian shore crab in only fifteen years (read about it here).

Gabriel said...

Hi Chris -

Some thoughts:

[i] You're correct that on ocassion the "long-run" isn't as long as we might expect. The key here is that this is only on ocassion, and that the long-run is orders of magnitude longer than the short-run. Thus, the rapid evolution of the mussel species that you cite is the rare case when the two time scales overlap. Normally, responses in population size occur about 1,000 times more rapidly than the development of genetic novelties.

[ii] Why was the mussel example an exception? It's hard to tell exactly without more research, but there are two possible ways that things could have happened. First, the mutation that conferred a response to the crab could have been present in the southern Maine mussel populations before the arrival of the crab. Second, the mutation that conferred a response to the crab could have arisen after the arrival of the crab. Knowledge of the population structure for the mussels could reveal which is the case, but in similar mussel species, local populations are often genetically distinct from other distant mussel populations of the same species. This, combined with known mutation rates, renders the second explanation extremely unlikely. Thus, we are left with the explanation that the mussels were able to adapt because one population already had a mutation to deal with the exotic invasive crab.

[iii] This happens extremely infrequently, which is why exotic invasives are predominantly really bad for diversity. A good review article from 2001, available at http://www.pnas.org/cgi/reprint/98/10/5446.pdf points out that invasives are bad for ecosystems, and that populations generally don't have the capacity to respond quickly enough evolutionarily. It notes that freshwater ecosystems may be the exception to this principle, but then goes on to cite examples of exotic invasives devastating freshwater ecosystems, like the Nile perch in Lake Victoria and the zebra mussel in most of North America. So, even the exception to the principle is largely subject to exceptions, putting it back in congruence with the original principle. Further, these systems only require one agent of extinction to mess them up. Again, wrecking these systems takes only a few years, while fixing them takes tens of thousands.

[iv] It can be comforting to ignore the short-term effects and focus instead on the long-term ones. This comfort is short lived. Allowing such extinctions to proceed without attempting to alter our behavior is immoral, and immorality can often cause some degree of discomfort. At some point, however, Homo sapiens will become another species subject to the turnover required of this widespread ecological and evolutionary degradation. I'm not comfortable with that.

Thanks for blogging. Keep up the good writing.