Thursday, November 22, 2012

How to save the Gulf of Maine cod fishery

What better time is there to talk about the Gulf of Maine cod fishery than today, considering the role seafood played in the Pilgrim’s first Thanksgiving feast? This week, Alison Fairbrother published an article bemoaning the scientific process in fisheries management, focused specifically on the cod fishery of New England. The article discussed the fate of a fishery with a long illustrious history, predating the Pilgrims. In a fascinating book on the subject, Cod: A Biography of the Fish that Changed the World, Mark Kurlansky suggested that Basque fishermen were fishing on these grounds before Columbus and may have influenced his decision to sail the Atlantic. Either way, the cod stock supported a prolific fishery for centuries. From colonial times, when it was most often preserved with salt, to the childhoods of baby boomers, when it came as fish sticks or square fillets, cod was the go-to white fish. Catches decreased gradually over the first half of the 20th century, built back up through 1990, and then were reduced dramatically, and Alaskan pollock became the new ubiquitous white fish. On the Canadian side of the border, the government shut down the cod fishery in 1992 because evidence suggested the stock had dropped to such low levels that they felt there was no other option, leading to economic collapse and a substantial exodus from fishing-dependent communities. Evidence suggests the cod stocks have begun to rebuild from a low in the mid- to late-1990s, but still have substantial way to go.

I have a personal connection with this fishery. My family roots reach back to the Mayflower. Also, the issues that are raised in the current controversy are near and dear to my professional interests. You see, uncertainty still plays a central role in one of the world’s best studied fisheries.

Despite being the focus of decades of research and analysis, Gulf of Maine cod present ongoing scientific mysteries. The most basic one, faced by all fisheries and virtually all renewable resource management systems, is that we cannot accurately predict how much new resource is on the way. In the case of fish, we can only estimate the number of babies that will be produced. As an alternate example, in managing a reservoir we have to rely on forecasts for how much new water will be coming in from upstream. In both cases, we have to make educated choices, which are essentially gambles. Though we cannot pick a single outcome, we can choose the size of our gamble (I’ll write more on these parallels and the gambling analogy in an upcoming blog).

The recent cod controversy was fueled by an assessment from 2008, which suggested that a strong class of fish born in 2005 would allow for continued fishing while allowing the stock to rebuild to a healthy level by 2014 (a timeframe specified under US fisheries law). Unfortunately, that turned out to be a false hope; the 2005 year class did not pan out, most likely because the data were a statistical fluke. Even with cod, where the government conducts extensive surveys to measure the population size over time, we only take samples of the actual population. Samples can give a wrong impression if they happen by luck to catch an unrepresentatively high or low number of fish. When discovered in 2011, this mistake left little wiggle room with a deadline to rebuild by 2014. The government scientists indicated that rebuilding was only possible if the fishery were essentially closed down.

To make matters more challenging, the fishing industry hired a clever scientist to represent them at meetings. Doug Butterworth presented an alternate assessment of cod in 2011. The key difference was an assumption by him that large fish were somewhat immune from fishing. Without this assumption, the government assessment interpreted the paucity of fish in recent scientific surveys as evidence that relatively few mature cod were out there. Butterworth’s twist enabled him to assume there were many mature cod; they were just beyond the reach of the fishing gear we would use to detect them.

Ever heard of dark matter? It was proposed to balance equations relating to the Big Bang theory, making up for the lack of observable matter in the universe. Dark matter at least had a theory to guide its assumed existence and recent evidence has begun to suggest it may be a reality. The proposal of dark fish, though, was simply motivated by the fact that we can’t rule out their existence, which is convenient for a fishing industry who feared the economic effects of a closure like the one Canada enacted 20 years ago. Amazingly, the US government enacted a compromise between its scientists and Butterworth, establishing a catch limit far in excess of what government scientists believed would allow rebuilding by the 2014 deadline. It may be convenient to blame Butterworth for this state of events. I certainly don’t respect his contribution. Others may blame aggressive Senators who were made aware of the controversy and pushed to have both sides heard. Both of these attributions are off. The problem was that the government regulators, in association with the fishing communities, had gambled big and lost. They may not have even realized they had done so until it was too late.

To me, this whole controversy feels like déjà vu. I worked for the government as a scientific adviser and later as a stock assessment scientist from 2003 to 2007. Early on, I was responsible for giving guidance to fisheries managers in the Gulf of Mexico about a fish species, the vermilion snapper, which had been declared overfished. Its status was not as dire as cod’s has been, but it fell under the same federal laws that set a deadline by which the stock had to be rebuilt to healthy levels. I was working with a management council that, like the one in New England, was not known for giving deference to its scientists. The Gulf council had already indicated they wanted a rebuilding plan that kept catches constant throughout the rebuilding plan. Economically, it is desirable to avoid booms and busts because busts cause major social disruptions and booms tend to drop prices. The problem with constant catch limits is they ignore the lessons of rocket science (see last week’s blog)—they are entirely unresponsive to evidence that the trajectory may need adjusting and represent a big gamble as a result. Instead of dogmatically pressing my idea of reasonable catch limits, or dreaming up dark fish, I educated the Gulf council.

In my analysis, I highlighted two significant consequences of a constant catch policy. First, since it would be applied to a growing population, regulations would feel tighter each subsequent year in order to maintain catches at a constant level while fishing an increasingly abundant and easy-to-catch stock. In addition to the regulatory challenges involved, they would also have to confront fishermen who were catching fish easily and would likely be of a mindset that rebuilding had already happened (a phenomenon I suspect has had some influence on New England cod fishers). Second and more significantly, I highlighted to them that stock assessments are uncertain. I illustrated a scenario—what if we had inadvertently overestimated the productivity of the stock by 10% and discovered the error on the next assessment four years in the future? I explained that such an error was certainly possible, and that, under their preferred plan, this discovery would have resulted in scientific advice to shut down the entire fishery. I never told them they couldn’t choose the catch limits they initially had preferred. I simply educated them about their weaknesses and highlighted how they were a bigger gamble than some alternatives.

In response to my advice, the Gulf council chose a rebuilding plan that dropped catches initially and allowed them to increase as the stock recovered. In short, they chose the sort of plan that was more likely to hit their target in an uncertain world, even though doing so would cause some social disruption. But, the advice worked. The most recent assessment estimated that vermilion snapper is exceptionally healthy and fully rebuilt ahead of schedule. We cannot revisit the past and try an alternate experiment. However I suspect the managers were much happier facing the fallout for some (justified) initial pain that has led to a healthy fishery than they would have been facing potential mutiny if, a few years later, they were considering a fishery closure just as I had warned was possible.

If we want managers, and even Senators, to make and/or accept some hard choices about the Gulf of Maine cod fishery, we have to teach them that decisions favoring fishing today increase the chance that unexpected events will lead to further restrictions tomorrow. Ultimately, managers have to perform a balancing act that takes into account the economic suffering deep cuts in catch limits would inflict and the potential for even greater suffering in the future. Doing this task properly requires that managers have a clear understanding of how much fishing communities are willing to pay now to reduce the size of the gamble with the future of their fishery. Thus, we should not limit the involvement of the fishing industry in the science by, for example, excluding hired guns like Doug Butterworth. We should welcome this involvement and even encourage other interested parties like conservation groups to hire scientists. We also need to ensure that scientific advice clearly describes our uncertainty about the future and the implications of that uncertainty. Feel free to lobby your favorite conservation group, fishing group, or government agency to formally request my help. Like Butterworth, I am for hire. Unlike him, my goal will be to use science to inform the inherent trade-offs in management choices and ultimately craft effective solutions that stand the test of time.

Happy Thanksgiving,

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