Maryland released its annual Juvenile
Abundance Index for striped bass a few days ago, and the news isn’t good.
To put that in context, the long-term average is 11.7. When the Atlantic States Marine Fisheries
Commission began recovering the collapsed striped bass stock in the 1980s, it
determined that a three-year rolling average of 8.0 would signal that the stock
had begun to recover.
So 2.2 is pretty bad.
Still, the Maryland Department of Natural Resources
correctly notes that a single year’s index provides no reason to worry. It issued a
reassuring statement which said
“While this year’s striped bass index is disappointing, it is
not a concern unless we observe poor spawning in multiple, consecutive
years. Very successful spawning years,
as recently as 2011 and 2015, should more than compensate for this
below-average year class. Nonetheless,
the department and our partners will continue to work to maintain a sustainable
fishery for our commercial watermen and recreational anglers.”
That sounds fine. But
if we remove the word “consecutive” from the Maryland Department of Natural
Resources’ statement, and take a broader look at striped bass abundance, does
the poor 2016 figure give cause for concern?
While there were dominant year classes in 2011 and 2015, the
worst spawn ever recorded in the 62-year history of the Maryland
young-of-the-year survey, 0.89, occurred just four years ago. Other than that record-low year, you have to
go back to 1990, when the collapsed striped bass stock was still struggling to
rebuild, to find a spawn that was worse.
Still, it’s true that some good year classes can make up for
the bad ones, so it’s worthwhile to take a look at some recent averages to see
where we might stand today.
The 3-year average is now 12.47, a bit above the long-term figure.
That’s good.
One the other hand, the 5-year average, which captures the terrible
2012 spawn but not the dominant 2011 year class, is a mere 8.81.
An average of the last 10 years captures both the two worst
and two best recent year classess, and returns a figure of 10.87, which
remains below the long-term average, but not by very much.
Thus, if we look at the averages alone, it would appear that
the Maryland DNR is right. The poor 2016
spawn is largely offset by more successful spawns in other years.
On the other hand, to determine the trajectory of the stock,
and figure out whether abundance is increasing or decreasing over time, you
need to look at trends.
They tell a somewhat different tale.
The long-term average reaches back six decades. During most of those years, striped bass were
hardly regulated at all, and overfishing was tolerated whenever and wherever it
occurred. The long-term average also includes
the spawning stock collapse of the 1970s and early 1980s, when rebuilding had
not yet begun.
A medium-term average that includes only the modern era of
striped bass management, the years after the stock had been declared rebuilt in 1995,
would yield a figure of 16.41, significantly higher than the long-term average,
and well above the averages for the most recent 3, 5 and 10-year periods.
Even if the starting point for such medium-term average was
moved back to 1986, when the ASMFC’s Striped Bass Management Board adopted Amendment 3
to the management plan and began the stock’s rebuilding, such average,
at 15.31, would still remain notably higher than the long-term average and the most recent
3-year, 5-year and 10-year averages.
Thus, despite having the large 2011 and 2015 year classes included in the mix, the last 10 years of striped bass reproduction, when viewed
through the lens of the past three decades, have not been particularly good.
In fact, the average for the past 10 years, 10.87, is the
third-lowest average for any 10-year period beginning on or after 1986. The only two 10-year intervals that returned lower
averages were 2004-2013, when the juvenile abundance index averaged 10.47, and
2005-2014, when the index averaged 10.55.
It’s probably significant that all three of the worst
10-year intervals in the past thirty years ended within the past four years.
In contrast, the best 10-year intervals since 1986 included
1992-2001, when the juvenile abundance index averaged 23.69, and 1996-2005,
when it averaged 22.24, more than twice the current 10-year average and ten times the 2016 level.
Even the average for the rebuilding period following the
collapse, 1986-1995, was 11.76, about equal to the long-term average and somewhat
higher than the average for 2007-2016.
Viewed against that background, the current state of striped
bass reproduction doesn’t look all that good.
Another factor also comes into play.
Biologists
have linked successful striped bass spawns with particular environmental
conditions, more specifically cool, wet springs.
Unfortunately, springs seem to be getting warmer.
Unless there is a drastic, and completely unlikely, change
in global weather patterns during the last two months of the year, 2016
will be the warmest year ever recorded.
Even taking 2016 out of the equation, the five warmest years on
record occurred in 2015, 2014, 2010, 2013 and 2005.
That’s a trend that doesn’t bode well for striped bass
spawning success in the long term.
In the short term, things look somewhat better.
The 2011 year class will begin recruiting into the coastal
fishery next season, so anglers that have already been catching a lot of
undersized 2011s will now be able to take a bass or two home. In the Chesapeake, the 2015s will also start
appearing in fishermen’s catches, although virtually all of them will probably
have to be returned to the water.
So long as harvest remains at 2015 levels, it is unlikely
that the stock will become overfished in the next few years.
The danger is that the abundance of smaller fish will lead
to further calls to relax the regulations imposed last year, pursuant to Addendum
IV to Amendment 6 of the Atlantic Striped Bass Interstate Fishery Management
Plan.
Hopefully, no such calls will be heard, for the 2016
update to the most recent benchmark stock assessment has already stated
that, at current harvest levels, there is only the slimmest possibility of the
female spawning stock biomass returning to target abundance by 2018. The small 2016 year class is certain to
further slow the recovery of the stock, even if landings remain unchanged.
Increased landings would make recovery even less likely,
and increase the possibility that the female spawning stock, already just
slightly above the overfishing threshold, would decline enough to fall below
that critical reference point.
Thus, all eyes should be on ASMFC’s Striped Bass Management
Board when it meets next week, and all anglers concerned with the health of the
striped bass stock should stand ready to challenge any rash effort, however
unlikely, to increase the kill.
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