DUBIOUS ASSUMPTIONS

In a perfect world, biologists wouldn’t have to estimate the size of fish stocks.  Someone would design a method that would count the number of fish, within 5% or so, with absolute reliability that works across the full range of species.

In that same perfect world, anglers’ catch would be fully documented.  Everyone who went fishing would report all of their catch—even when they caught nothing at all—using an application that would calculate landings, catch per unit effort, mode and landings compositions, and how everything changes year to year.

But we live in an imperfect world. 

Stock assessments contain imperfections, even those for data-rich stocks such as striped bass.  When dealing with data-poor stocks such as black sea bass, managers are nearly flying blind.  And when it comes to estimating anglers catch, fishery managers are trying hard to improve their accuracy, but still have a long way to go.

However, managers have to do their job with the information on hand.  That means that, at times, they have to use the best available data, coupled with a large degree of caution, to keep healthy stocks healthy and to rebuild those that have become overfished.

At times, that makes fishermen unhappy, particularly when very conservative management measures are imposed to prevent overfishing what people perceive to be a very abundant stock.

One of the best examples of that is black sea bass.  In the northeast and mid-Atlantic, black sea bass abundance appears to have increased substantially.  Anglers are catching far more than they used to, and voices in the recreational community frequently complain that regulations are far too restrictive.

Fisheries managers fall back on available data when trying to craft regulations.  They know, and will freely admit, that better data is needed to manage the black sea bass fishery, and hopefully, after a benchmark stock assessment is completed late this year, at least somewhat better data will be available.  Until then, they will try to do the right thing with the tools that they have.

Anglers, on the other hand, have no legal responsibility—moral responsibility, of course, being something else altogether—to manage the stock for sustainable harvest and future abundance.  All that a lot of them know is that they see a lot of fish when they go fishing, and want to be able to up their kill.  

Businesses that serve such anglers are also pretty quick to condemn managers’ efforts, since they imagine greater profits flowing from bigger fish kills.  Maybe the best example is a local party boat captain who complained about one of my blogs, telling me that

“Your [sic] a disgrace.  Your scientific bullshit is putting our sea bass fishery in the toilet.”

Now, I probably should point out that it’s not my “scientific bullshit.”  

I’m not a biologist.  I just know some biologists, and read the work put out by others.  I have, over the years, developed a real respect for some very bright people who do a very tough job for a very small financial reward. I just report what they say.

They know that their work isn’t perfect.

We all know--or, at least, we should--that it’s the best work that the available data and funding allow.

And we should admit that, with all its imperfections, it’s quite a bit better than what the anti-science folks would have us depend on, which are essentially any assumptions, unsupported by data, that would support their argument to relax regulations.

More restrictive black sea bass regulations have seen those assumptions spew out at a fever pitch.  They’re numerous and, ever so often, sort of amusing.

As a rule, the assumptions deal with estimates of recreational harvest, either the old Marine Recreational Fisheries Statistics Survey, generally referred to as “MRFSS”, or the work-in-progress “MRIP”, which is short for “Marine Recreational Information Program”. 

The assumptions usually arise out of the fact that no statistical estimate is perfectly precise—there is always some acknowledged level of error—and the fact that MRFSS, in particular, contained a number of statistical flaws.  Folks with no real knowledge of statistics, and no desire at all to learn how things actually work, will harp on such inherent errors to smugly assume that any data coming out of MRFSS or MRIP that doesn’t support their notion of what the facts should be must be wrong.

I was reminded of that the other day.

The folks at MRIP were reviewing data before finalizing 2015 harvest numbers, and determined that the preliminary landings estimates for black sea bass seemed to be low.  The revised harvest estimate was 16% higher, when based on the number of fish, and 9.6% higher, based on weight, than the preliminary numbers, which meant that 2016 regulations, already very restrictive, were theoretically not restrictive enough. 

That obviously caused a furor, and that’s when the assumptions kicked in.

For years, Capt. Monty Hawkins, who owns and operates a Maryland party boat, has been attacking black sea bass regulations, for various reasons. 

He has long assumed that the decline in the abundance of the black sea bass off Maryland has nothing to do with warming water temperatures, as the National Marine Fisheries suspects, but on more restrictive regulations that ultimately suppress spawning success. 

The way he explains it is that

“When sea bass perceive they’re under pressure at reefs close to inlets where fishing pressure is heaviest and therefore begin spawning at the youngest age possible; more distant reefs become overpopulated owing to nearshore overproduction.

“Hence ‘surplus production, which is at the very heart of fisheries management.

“Surplus production is what allows us to take any fish at all.  A true understanding of spawning production, and not grasping convenient popular theory, is what will make or break today’s early attempts at marine fisheries management.

“The evidence for elevated production is made plain in sea bass management’s earliest years.  Scientists who manage dozens—dozens—of other fisheries scoff and blame it on a ‘lucky year’ in production.”

But Capt. Hawkins doesn’t buy the 'lucky year' hypothesis for a minute.  Fortunate enough to lack scientific training, or years working with similarly trained colleagues in the scientific field, he knows what the real problem is.

“We taught sea bass not to spawn until age 3 & the population plummeted.”

A lot of folks are happy to have Capt. Hawkins around to explain that, because they know that you’d never hear a scientist say that we’d have more black sea bass around if the size limit was dropped to nine inches.  Yet the good captain’s assumptions of why there used to be more fish off the Maryland shore clearly shows that it’s true…

He also loves to attack MRIP, and particularly its estimates of private boats’ recreational harvest, saying things such as

“MRIP is making regulators crazy.  The tragedy is unfolding before our eyes as recreational fisheries are closed.

“I’m digging—looking.  Re-reading old works.  What on earth can I possibly use to show management how utterly bizarre their belief in MRIP’s catch estimates seem to us?  This stuff is just NUTS to anyone working in the recreational fishing trade.  There’s just No Way Private Boats from one state can outfish all US Party/Charter.  It’s doubtful any one state’s Private Boats catch more sea bass than just their own state’s Party/Charter fleet.  But NOAA believes the estimates.  After all, they paid for them ..and then get paid to use them…”

With respect to the for-hire estimates, Capt. Hawkins complained that

“The good news is that someone at NOAA is actually looking at [Vessel Trip Report] Catch Reports.  These are not broad two-month Catch Estimates.  We report, on a NOAA form, what we land everyday.  Be nice if management were told what those reports say instead of MRIP’s nonsense.”

Capt. Hawkins wants to see black sea bass regulations relaxed, so he makes an argument that MRIP’s numbers are bad, and that private boat anglers caught less than estimates show, saying that “It’s doubtful any one state’s Private Boats catch more sea bass than just their own state’s Party/Charter fleet.”

What if he’s right—just not in the way that he intended?

It appears that may well be the case.

Capt. Hawkins, in making his argument, never seems to consider the possibility that the private boat estimates aren't too high, but instead, that the charter boat estimates were far too low, although that seems to be what’s driving the revised numbers for 2015.

Moreover, the finding that charter boat landings were higher than originally believed came from the MRIP folks doing exactly what Capt. Hawkins wanted—incorporating vessel trip report data into the landings estimates.

It’s going to be tough for him to contest numbers derived, at least partially, from a procedure that he endorsed, but I won’t be surprised if he tries.

Because that’s how it is with assumptions.  You always assume that you’re right, even when the data says otherwise.

And it’s not just Capt. Hawkins who makes assumptions that, to be kind, are not robustly supported by data.  He just leaves a good written record that contains some fine quotes.  

At the most recent meeting of New York’s Marine Resources Advisory Council, another perennial critic of MRIP estimates got up and asked something like

“How could New York’s charter boat landings be eight times higher than they were in past years?”

I felt like saying

“Maybe they finally got it right,”

but saw no reason to toss gas on that particular fire, even though my answer might well have been true.

The bad news is that there is still a real chance that the MRIP numbers will be further revised; the good news is that New York will be supervising the data gathering within the state this year, and it is very likely that a lot of the bugs missed by the federal contractors will be corrected by folks familiar with our local fishery.

Of course, that won’t fix the problem, since folks who make baseless assumptions also assume that anyone they disagree with is wrong.