New Data Change Summer Flounder Outlook
By Charles A. Witek
Vice Chairman, CCA National Government Relations Committee
A long time ago, someone down in Washington, D.C. said, “If it ain’t broke, don’t fix it.” The recent summer flounder stock assessment, released in late July, demonstrates that such advice clearly applies to the fisheries management system.
Over the past few years, anglers have certainly heard enough complaining that the fisheries management process is, in fact, broken. Summer flounder have been the species most often used to illustrate the system’s problems, and CCA has come in for its share of criticism for supporting the management process and the conclusions of fisheries managers.
Now, with the release of the 2008 summer flounder stock assessment, we find our faith in the system vindicated.
Some might be taken a little aback by that statement. Didn’t CCA support the 197 million pound spawning stock biomass rebuilding target? And didn’t the newest assessment find that a spawning stock biomass of 132 million pounds would produce maximum sustainable yield?
The answer would be “yes” to both, but that doesn’t matter, for what CCA has always supported wasn’t the FIGURE of 197 million pounds, but the PROCESS by which such figure was determined to represent the best available science. And that process was just as valid in 2005, when the 197 million pound figure was developed, as it was in 2008, when the 132 million pound figure was devised.
That process represents good science, and science is a living thing that evolves and changes as new information becomes available and more data is added to existing population models.
Today, we’re seeing some environmental groups that fought very hard to defend the 197 million pound biomass target expressing outrage that the target has been lowered. We’re also seeing fishing industry groups who were relentless in their attacks on the former biomass target crowing about their “success” in getting the target reduced to 132 million pounds. All of them are missing the point. Both assessments represented the best available science at the time the assessments were made. Both were put together by the Southern Demersal Working Group, and both were peer reviewed by a panel of international experts. To adopt one as “good science” and the other as “bad science” is to do nothing more than to cherry-pick the version that happens to best support your argument. However, to call the 2005 assessment “old science” and the 2008 “new science” would be right on the mark.
Let’s take a look at what really happened.
The 2005 assessment’s 197 million pound spawning stock biomass target was based on data observations made through December, 2004. It used observed data regarding a fluke’s size at various ages, historic (since 1992) data on spawning success and estimates of a summer flounder’s average lifespan to calculate the size of the spawning stock biomass that would produce maximum sustainable yield. It also estimated natural mortality at M=0.20, which means that about 18% of the fluke population dies each year from non-fishing-related causes.
However, the population model that was used in the assessment also revealed a “retrospective increase” in summer flounder mortality. That is, it indicated that fewer summer flounder survived each year than predicted by the model, when commercial harvest, recreational harvest and natural mortality were taken into account. Biologists could not identify the cause of such “additional” mortality, but guessed that it probably was related in some way to fishing effort, whether in the form of unreported commercial landings, greater-than-expected discard mortality in commercial and/or recreational fisheries and the harvest of illegal fish by commercial and/or recreational fishers. Such unidentified mortality, and the failure of fisheries managers to allow for such mortality when setting annual harvest limits, played a large role in the ever-decreasing landings quotas that we were forced to endure in recent years.
This year, the scientists assessing the summer flounder population had three additional years of data, allowing them to use information compiled through December, 2007. Such additional information proved critical.
Perhaps the most important bit of information related to the maximum age of summer flounder. When the current management program began in 1992, harvest levels were so high that very, very few summer flounder were able to live for more than two years. However, as managers began to impose meaningful restrictions on the fishery, the size of the population began to expand, and the number of age classes represented in the fishery increased. There is now sufficient data to suggest that male fluke only live for 12 years, while females live to be 14 years old. That is information that just wasn’t available in time for the 2005 stock assessment (as fish more than two years old were very scarce in 1992, it wasn’t until 2004 that a significant number of 14-year-old summer flounder could be represented in the population, and it took a few more years to demonstrate that fluke normally didn’t survive to even greater ages.) Once it was available, it allowed fisheries managers to take a fresh look at natural mortality, and determine that a higher rate, M=0.25, probably was a better reflection of reality. That determination was supported by the known life histories of other flatfish populations, which experience a similar rate of natural mortality.
The higher natural mortality rate, when combined with updated weight-at-age data applied to the population model, suggests that the spawning stock biomass which would produce maximum sustainable yield is lower than previously thought, in the range of 132 million pounds, which is about 35% of the size that the population could attain with no fishing at all. Biologists have suggested that managers use a higher spawning stock biomass target, of about 151 million pounds, about 40% of the stock size if no fishing took place. That is significantly lower than the former spawning stock biomass target, so the commercial and recreational fishing industry members who attacked the old target as “unattainable” are declaring a great victory.
But what, exactly, did anyone win?
By lowering the spawning stock biomass target, biologists were, in effect, declaring that the summer flounder population is less productive than once thought. Thus, we will never see the 47 million pound harvests, and 19 million pound recreational share, that would have flowed from a spawning stock biomass of 197 million pounds. Instead, the smaller spawning stock suggested by the last stock assessment will yield just 28 or 29 million pounds, and recreational fishers will never be able to take more than 11.5 million pounds of that, putting us in about the same position that we were in during the 2004 season.
Thus, while the new stock assessment almost certainly means that anglers will fish under slightly relaxed regulations in the short term, and that they might take home a few more fish during the rebuilding period than they would have if the spawning stock biomass had remained at 197 million pounds, the tradeoff is that, once the stock is fully recovered, harvests will still have to be closely regulated, as 132—or even 151—million pounds doesn’t provide enough fish to satisfy the demands of both the recreational fishery and commercial markets. Still, although the new assessment ultimately means reduced harvest and reduced opportunity for anglers, CCA cannot contest the outcome. CCA is committed to science-based fisheries management, and the integrity of the stock assessment peer review process. The new assessment is the fruit of such a process, and thus demands our support, even if it means that, in the long term, recreational harvest will never be as large as we, and we suspect many anglers, would have liked to have seen.
In fact, the new assessment has not only vindicated our faith in the process, but also in the law. For the last few years, we have seen some fishing industry spokesmen calling for what they call “flexibility” in the Magnuson-Stevens Fisheries Conservation and Management Act, the law that governs all fisheries management in federal waters. The law, they claim, must be changed to address the biological uncertainty inherent in the management process. The law, they say, forces fishers to live under impossibly strict management measures, engendered by unrealistically high rebuilding targets.
The 2008 summer flounder stock assessment, though, has demonstrated how “flexible” the Magnuson Act really is. When presented with new scientific data, the biologists analyzed it, and incorporated the results into the new assessment.
When calculations, and not mere conjecture, brought the rebuilding target into question, that target was reduced to accord with newly developed information. While the management process doesn’t respond well to politically motivated arguments, and isn’t designed to let a handful of people profit at the expense of a public resource, when confronted with good data and verifiable scientific evidence, the process proved flexible indeed.
Source:
http://www.ccanc.org/index.php?xnews...82008&newsid=2
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