Sunday, November 5, 2017
STRIPED BASS--SAME FIGHT, DIFFERENT DECADE
At the dawn of the 21st Century, anglers and fishery managers were fighting over striped bass.
More particularly, they were fighting over how the fish should be managed—for maximum yield, which suggested some level of growth overfishing and a spawning stock that lacked most of the older, larger and most fecund females, or for a larger, stable, sustainable population that included a wide range of ages and sizes, but yielded a somewhat smaller annual harvest.
A large number of anglers, many of whom had fished for striped bass before and during the stock collapse of the late 1970s and early 1980s, argued that the latter approach would, in the end, be best for both fish and fishermen.
“The job’s not done until we bring back the big bass,”
they pointed to research such as that referenced in a joint National Marine Fisheries Service/United States Fish and Wildlife Service report, which noted, in part, that
“The distribution of age classes in a population has important implications for stock productivity and stability. Studies on striped bass have shown that larger fish produce larger eggs and larvae, and larger individuals of these life stages have a greater chance of survival.”
At the time that debate was going on, fishery managers were generally focused on obtaining maximum sustainable yield from fish populations. Managing for MSY generally results in a population that, while able to maintain itself under normal circumstances, is fairly small and made up primarily of smaller individuals; the relatively high annual harvest rate assures that most fish will be removed from the population well before they attain a large size or older age.
Although the smaller individuals each contribute relatively little to the spawning stock, they make up for low individual fecundity with high levels of abundance, and collectively produce enough spawn to produce average recruitment over the long term.
However, a spawning stock that is comprised of just a few age classes, and is subject to relatively high levels of fishing mortality, is vulnerable to recruitment failure. Should it experience consecutive years of below-average spawning success, while mature adults are steadily removed from the population, the size of the spawning stock can quickly decline. With few larger, older fish in the population to provide a reserve of fecund females, the spawning potential of the stock will plummet and the stock can easily collapse.
That is essentially what happened to striped bass during the late 1970s and 1980s, when recruitment in the critically important Maryland spawning areas tanked for 14 years, beginning in 1975. Such poor recruitment, coupled with excessive harvest, caused the stock to collapse, and required heroic measures on the part of fishery managers to nurse it back to health.
Not wanting to see history repeat itself, the anglers argued for lower harvest levels that would lead to a more resilient stock in which the older age classes were well-represented.
In more recent years, the need for such a well-stratified stock—one which includes substantial numbers of what biologists now sometimes refer to as “big, old, fat, fertile female fish”—has become well-accepted among mainstream fisheries scientists. But fifteen or twenty years ago, the anglers who sought to elevate the long-term health of the striped bass stock above the opportunity for a large near-term harvest were staking out a seemingly radical and certainly controversial position.
The depth of the controversy was illustrated by the differing opinions held by various members of the Atlantic States Marine Fisheries Commission’s Striped Bass Management Board; the split didn’t merely divide different state delegations, but separated representatives sent to ASMFC from a single state.
For example, at the Management Board’s December 2002 meeting, Pat Augustine, the Governor’s Appointee from New York, put forward a motion that would maintain the target fishing mortality rate at 0.30, a level that would allow about 26% of the adult population to be harvested each year.
In response, Gordon Colvin, who represented the New York Department of Environmental Conservation’s Marine Bureau, argued for a more conservative harvest level, saying
“as stated by some of the advisors, there is a clear indication in this amendment of an objective that would accelerate, to the extent that it’s reasonable to do so, the aging of the population, and it will accelerate faster at a lower mortality rate.
“Our own analysis show that consistent with the stated objective of the plan…”
The end result was Amendment 6 to the Interstate Fishery Management Plan for Atlantic Striped Bass, a management document that managed to satisfy neither side. While the new Amendment, adopted in 2003, acknowledged that
“1) There is growing concern that the management program contained in Amendment 5 may not be appropriate to prevent the exploitation target in Amendment 5 from being exceeded.
2) Over the past few years many members of the fishing community have raised the concern that the availability or abundance of large striped bass in the coastal migratory population has decreased,”
“To perpetuate, through cooperative interstate fishery management, migratory stocks of striped bass; to allow commercial and recreational fishing consistent with the long-term maintenance of a broad age structure, a self-sustaining spawning stock; and also to provide for the restoration and management of their essential habitat, [emphasis added]”
and clear objectives to
“Manage striped bass fisheries under a control rule designed to maintain stock size at or above the target female spawning stock biomass level and a level of fishing mortality at or below the target exploitation rate”
“Manage fishing mortality to maintain an age structure that provides adequate spawning potential to sustain long-term abundance of striped bass populations,”
it also failed to reduce the target mortality rate, which made the Amendment’s acknowledgements, goal and objectives ring somewhat hollow.
Unfortunately, those who sought to reduce fishing mortality ultimately found themselves justified, for the female spawning stock biomass peaked in 2003, the same year that Amendment 6 was approved, and then began a long slide from which it has not yet recovered.
A new benchmark stock assessment, released in 2013, not only documented the decline, but advised that the Amendment 6 reference points were, as some of us had warned a decade before, far too high.
New, lower fishing mortality reference points—a target of 0.18 and a threshold of 0.219—were adopted in 2014. An update to the stock assessment indicated that, at the end of the 2015 fishing season, the female spawning stock biomass stood at 58,853 metric tons, well below the 72,032 metric ton target and just slightly above the 57,626 metric ton target that denotes an overfished stock.
Those are the sort of numbers that should make fishery managers realize that that health of the striped bass stock is not as robust as it should be, and cause them to act in a very conservative and precautionary manner until spawning stock biomass shows a material increase.
Unfortunately, some managers want to act in a very different manner. At the Striped Bass Management Board meeting held last October, representatives of the Chesapeake Bay jurisdictions, led by the Maryland delegation, along with the usually conservation-averse representatives from New Jersey and Delaware sought to increase striped bass mortality by convincing the rest of the Management Board to consider reference points that take into account not only the biological needs of the striped bass, but also various “socio-economic” considerations.
“Current [fishing mortality] target and threshold are those that will maintain the populations at [spawning stock biomass] target and threshold.
“There is a trade-off between preserving [spawning stock biomass] and allowing fishing.
“The Board has raised concerns that the current [biological reference points] are too conservative for various biological, ecological, and socio-economic reasons, and may be restricting fishing unnecessarily.”
The Management Board has appointed a working group to look into the issue and make a recommendation, which the Management Board can either adopt or reject.
In other words, here we go again. The same arguments that we faced when Amendment 6 was being drafted are, like a B-movie monster, coming back to life just when we thought they were finally dead.
Except this time we know that the striped bass stock slid downhill when fished at higher levels, and that bass are far less abundant than they were just ten years ago.
When it comes to fisheries issues, those who expect the worst are seldom disappointed, so it’s probably time to get ready for another fight. This one will likely be short and sharp, and focused on ASMFC’s February meeting, when the reference point issue will probably be decided.
If the decision favors socio-economic factors instead of biology, that decision will almost certainly infect the next stock assessment, and damage the striped bass management process—and the health and abundance of the striped bass stock—for at least the next five years, if not beyond.
So have a nice holiday season, and be ready to speak up for the striper when the New Year begins.
Because it might be a new year soon, but the same old fight is still going on.