"OVERFISHED" STOCKS: WHAT'S IN A WORD?

Most people, even if they live in Nebraska and never saw an ocean, would probably agree that “overfishing” is bad and that stocks should not be “overfished”.  Which is probably why a lot of the same folks who want to weaken federal fisheries laws are trying to eliminate the term “overfished” from the Magnuson Act, and replace it with the term “depleted”.

“Overfished” has fallen out of favor, we’re told, because it suggests that fishermen are at fault every time that a stock declines (http://homernews.com/homer-news/business/2014-02-19/federal-fishing-act-getting-attention).  And that is supposedly a bad thing.

The House of Representatives bought into that argument.  Its current draft bill to reauthorize—and emasculate—the Magnuson Act would remove all references to “overfished” stocks and instead call such stocks “depleted”.  

Apparently, the same Congressmen who deny that people can cause climate change feel free to blame declining fish stocks on global warming.     

The first institutional use of the term “depleted” in place of “overfished” probably occurred at the Atlantic States Marine Fisheries Commission.  That makes a certain amount of sense, since the term “overfished” only has legal significance in the Magnuson Act, which doesn’t apply to ASMFC.  It also made a kind of sense because some of the “depleted” stocks managed by ASMFC run up rivers either to spawn (river herring, Atlantic shad) or to spend their lives prior to spawning (American eel), and influences such as dams, which cut off access to much of the species prior inland range, might actually cause stocks to decline in the absence of any fishing at all. 

Of course, if dams and such placed the fish in great peril, fishing could only increase the risk to the stocks.  So one has to wonder why ASMFC waited so long before imposing meaningful restraints on fishing for shad and river herring, or why Maine fishermen may kill juvenile “glass eels” at all…

Because, in the end, fishing mortality is always a part of the problem, and that’s where the fans of “depleted” go wrong.  If a stock is facing increased stresses from climate change, habitat loss, disease, predation or some other factor, fishing mortality becomes a critical issue.

Here’s why.

There are only so many ways that a fish can die, or that a stock of fish can be forced into decline. 

Fish can be eaten, die of parasites or disease (Mycobacteriosis in striped bass), or be killed by a sudden change in the weather (speckled trout off Virginia and North Carolina this winter).  That all falls under the heading of “natural mortality”.

Or fish may be killed by fishermen.  Those fishermen may be recreational or commercial.  They may kill the fish by harvesting them, or by hurting them so badly that they die after (or, in the case of many commercial fisheries, before) being returned to the water.  But all fish killed by fishermen constitute “fishing mortality”.

"Total mortality" is a combination of both natural and fishing mortality.  

Because fish die, new fish have to be “recruited” into the population to replace them.  If the recruitment rate is equal to the total mortality rate, the population will remain stable.  But if recruitment falls below the mortality rate, perhaps because of environmental conditions on the spawning grounds (Chesapeake Bay striped bass), excessive predation on juvenile fish (southern New England/Mid-Atlantic  winter flounder) or interspecies competition (the “bottleneck” of Year 1 weakfish), the population will decline.

If a stock’s natural mortality rate increases, fishing mortality must be decreased to keep total mortality constant.  If fishing mortality isn’t cut (assuming that the recruitment rate doesn’t change), fish will be killed faster than they can be replaced.  Abundance will decline, and when it does, the stock won’t be “depleted” by conditions outside of human control.  It will be “overfished”.

The same thing holds true if recruitment declines while mortality remains constant.  Fish will again be removed faster than they can be replaced.  And again, the only realistic way to prevent a stock decline is to restore the balance between removals and recruitment by reducing fishing mortality.  Fishermen will need to kill fewer fish.  If they fail to do so, they shouldn’t escape responsibility by calling the stock “depleted”.  For it is truly “overfished”; reducing harvest would have fixed the problem.

It’s unfortunate, but fishermen seem to think that a big part of fisheries management is about blame.  If they can blame some outside agent—seals, dogfish, warm water, cold water, habitat loss, etc.—for a stock decline, they’ll argue that the decline wasn’t their “fault” and that they shouldn’t be “penalized” with harvest reductions as a result.

They just don’t seem to understand that, if the stock collapses, the reason for the collapse won’t matter; there still won’t be anything left to catch (for a recent, real-world example of this, see the earlier post “Of Stock Collapse, Shrimp and ASMFC” http://oneanglersvoyage.blogspot.com/2014/01/of-stock-collapse-shrimp-and-asmfc.html). 

It’s a lot like a homeowner who has a neighbor that smokes in bed.  One day, the inevitable happens, and the neighbor sets his mattress on fire.  So the homeowner sees it and says “I told the guy to stop smoking at night; it’s his problem,” and doesn’t call the fire department.

Eventually the neighbor’s whole house is engulfed in flame, and the wind blows some cinders toward the homeowner’s abode.  He could get a hose and start spraying some water on his roof, to put out any cinders that might be smoldering there, but then thinks “Why should I go to the trouble.  I didn’t start the fire,” and in the end, does nothing.  He doesn’t even go outside, where he might have noticed the low orange flames when his shingles started to burn, because he didn’t do anything wrong, and he couldn’t see why he should be inconvenienced because his neighbor did something dumb.

And after the homeowner’s own house lay in crumbling ruins, and everything that he owned or valued was reduced to ash and char, he calls out and says, “I didn’t sit idle and let my house “burn”, it was “ignited” by my neighbor.  I had nothing to do with it.”

But “burned” or “ignited”, the house was still gone, and the homeowner could have kept that from happening.

In the same way, whether we call them “overfished” or “depleted”, overstressed fish stocks will still collapse, unless managers cut harvests to prevent it.

Merely changing a word will not change that reality.