Sunday, April 6, 2014

"SUSTAINABILITY IS THE MINIMUM"

When the Sustainable Fisheries Act of 1996 was signed into law, it was big news.

Over all, our salt water fisheries were in pretty bad shape.  New England groundfish, in particular, had been hit very hard; the great shoals of cod and haddock that had fed the western world for nearly half a millenium had slid past the brink of collapse.

Fisheries law had supported what, in the jargon folks are use today, might be called “maximum economic yield”; “optimum yield”, required by statute, was maximum sustainable yield “modified” by, among other things, economic factors.  And those economic factors always resulted in MSY being “modified” upwards.

Overfishing was sanctioned by law.  Widespread stock collapses were only a matter of time.

So the Sustainable Fisheries Act, which mandated that overfishing immediately cease and that stocks be promptly rebuilt, was radical stuff for its time.

Which gives a pretty good idea about how far we’d fallen by then. 

The idea of not fishing stocks into oblivion, and making them more productive in the long term, transcends the realm of conservation, and enters the realm of plain common sense.  Yet the Sustainable Fisheries Act was controversial when it was written, and if anything, it is more controversial today.

Which gives a pretty good idea about how far we still need to go.

For the Sustainable Fisheries Act’s core tenet—that fish stocks be rebuilt and harvests be reduced so that the greatest long-term yield may be achieved from each population—isn’t an end, but a beginning.

It defines maximum sustainable yield.

Last week, I attended the National Marine Fisheries Service’s 2014 Recreational Saltwater Fishing Summit.  One of the speakers was Dan Wolford of California, a recreational fisherman and a three-term member of the Pacific Fishery Management Council.  One of the slides that he presented to the audience began with a simple statement:

“SUSTAINABILITY IS THE MINIMUM”

That just about says it all.

Because if we manage for maximum sustainable yield, our fish stocks won’t get any smaller and, once they’re technically “recovered,” they won’t get any bigger, either.  The notion underlying maximum sustainable yield is to harvest every single fish that isn’t needed to produce the next just-big-enough generation.

What you end up with is a smallish population—usually around 30% of the size of an unfished stock, give or take a bit, depending on a species’ biology--that includes a lot of fish barely old enough to reproduce.  It’s a good stock structure for commercial fishermen, as it lets them land a lot of fish year after year without hurting the population, and it gives them a catch made up of the sort of smaller, younger fish that the market usually prefers.

But that’s not the kind of stock structure that anglers and scientists really want to see.

There are a lot of recreational fishermen, scattered along the entire coast.  They usually fish close to home, often for just a few hours at a time.  They use inefficient gear and, as some will admit in private, often don’t use it too well.

For anglers to catch enough fish to keep things interesting, those fish must be abundant, not just in one place, but along long stretches of shoreline.  There needs to be enough of them that folks who can’t travel long distances, or put in long days, can still have a realistic chance of catching something they might want to take home, even if they’re not expert fishermen.

And more experienced—or just more hopeful—anglers will want the chance to encounter a large fish from time to time.  “The big one that got away”—or the big one that didn’t—has always been a part of angling lore and the chance of running into such fish lends spice to the fishing experience.

But managing for maximum sustainable yield won’t provide either the abundance or the size that anglers desire.

Nor will it provide the kind of healthy, productive stock that biologists like to see.

A few years ago, fisheries scientists often spoke of the need for “BOFFs,” an acronym that meant the kind of “Big, Old, Fat Fish” that are the sign of a healthy population.  Although some species prove an exception, such large individuals generally produce more eggs, and more eggs per pound, than smaller fish, and often also produce larger fry that are more likely to survive.  They also add stability to a stock, in the event something unexpected occurs.

If you manage a stock for MSY, you are always on the cusp of “growth overfishing,” a situation where the abundance of fish—and overall biomass—remains relatively high, but almost all of the fish are caught before they have a chance to grow large.  In such a population, all of the spawning is done by relatively few year classes.  Should some event—say, a change in  water temperature or other environmental condition—cause a few years of consecutive spawning failure, the stock can quickly get into trouble, as the mature fish are harvested and too few young fish are recruited into the stock to replace them.  

Think of the striped bass collapse in the late 1970s and early 1980s, and you’ll realize how fast a theoretically healthy population can get into bad trouble.

On the other hand, a stock that is managed more conservatively—not for maximum sustainable yield, but for “optimum yield”, by considering “social and ecological factors” and reducing landings accordingly—is far more resilient.  Instead of containing just a few adult year classes, it will have a spawning stock that includes both some large, old individuals and a lot of smaller, barely mature fish.  Should some event lead to serial spawning failures, a lot of year classes may be missing, but the larger individuals—fewer, but more fecund—will take up much of the slack and keep the stock viable until recruitment improves. 

That is more or less where striped bass are today.  Although not as abundant as they were a few years ago, there are still enough older spawners around to keep the stock going until the big 2011 year class matures.  That’s way we need to cut harvest now—to keep more big fish alive, and assure that the stock will really rebuild.

And that’s why anglers must pay no heed to the seductive calls for adding more “flexibility” to the rebuilding mandates of the Magnuson Act.  They will only delay rebuilding and leave fish stocks much more vulnerable than they are today.  

“Flexibility” sounds nice, but it increases the odds that something—perhaps warming waters, perhaps overfishing, perhaps something still unforeseen—will interrupt the recovery process and lead to big problems at some point down the road.

Flexibility won’t give us what we need.

And sustainability is not good enough.

Anglers want—and the fish need—abundance, and enough of big fish to breed healthy stocks.  That means annual catch limits that are low enough to produce large, well-structured populations, and not just maximum sustainable yield.


There’s no reason to settle for less.

No comments:

Post a Comment

Post a Comment