The US Department of Commerce under which marine fisheries are managed has just increased the quota for New England pollock from 6 million pounds to 36 million pounds. A six fold increase!
The reason given was that the original assessment of the species was wrong and that "new science" has shown that there are plenty more pollock than they thought. Of course intensive lobbying by industry and our elected representatives certainly helped in the ready acceptance of the "new science" by the Secretary of Commerce. [Off point: why are fish managed by the Commerce Department and not the Department of the Interior like buffalo or wolves? I bet you can guess!]
So how is it possible that the estimates for a marine fish population can be so terribly wrong? The simple reason: marine fisheries science is based on flawed assumptions, incomplete models and supported by inaccurate and incomplete sampling methodologies.
This fact is the 800 pound gorilla in the closet of marine fisheries management. The basic science underlying fisheries management was memorialized in treaties after WWII- the often cited "maximum sustainable yield" ("MSY"). This concept was at the time a hypothetical assumption based on the centuries old perception that the oceans were a limitless resource. In fact, the resource was vast, but certainly limited as we now know. Unfortunately the hypothetical MSY was already the treaty established standard in international marine fisheries management; and no one has been willing to change what has turned out to be the best possible formula for the commercial fishing industry.
Thus, for decades marine fisheries managers have been justifying and tweaking MSY to support the various fish quotas set-mostly with poor results. The mathematical models have gotten better for sure, however the ability to sample and evaluate fish populations in the wild has not not improved nearly as much. As we all know from basic computational science: "garbage in; garbage out." So that is where we are at with fisheries management- we are plugging in inaccurate and often blatantly wrong numbers into models that are incomplete and never fully validated. Result? Fishery science is largely guesswork that is only truly verifiable when a species disappears.
Disappearing, by the way, can happen on two levels when it comes to fish- ecologically and biologically. Ecological extinction has already occurred with blue fin tuna, that is, blue fin tuna no longer fulfill their role in the ecosystem as a dominant apex predator. Biological extinction has yet to catch up with blue fin tuna as evidenced by the fact that fishermen are still catching the fish and shipping it off to grace our sushi bars.
To illustrate the difference between biological and ecological extinction, picture there being five lions left in all of Africa- so there are still lions left, but are they performing their expected role in the ecosystem? My guess is many a zebra family will sleep easier if there were only five lions remaining that want them for dinner- in fact they will do more than just sleep!
By overfishing apex predators we dramatically alter the marine ecosystem in ways that overfishing prey fish would never do. And yes, as you probably recognize, most of our favorite fish to eat are higher up the food chain with the resulting disproportionate effects on the entire marine ecosystem. The chart above highlights the effects overfishing of predator fish has on the entire ecosystem. This graphic, while helpful in visualizing the effects of fishing, is not so easily modeled and even harder to quantify which is why marine fisheries managers have an impossible job.
Thus, the effects that marine fishing has is nearly impossible to model on a single species basis- which is exactly what marine fisheries managers attempt to do every day. There is no mystery then as to why marine fisheries management is a doomed enterprise and as a result our oceans will never be able to rebound from centuries of overfishing without a dramatic cessation of industrial fishing.
I note that fishing down the food chain is also problematic. It is not as simple as saying let's skip the tuna fishing and go for the sardines. In so doing we essentially flood the oceans with planktons and their jelly fish friends as the previously referenced chart highlights. This is not so good. Jelly fish are wreaking havoc in many local ecosystems with increasingly negative impacts. As for plankton, while at one level they absorb CO2 (good) they also increase ocean acidity (bad). This acidification of the ocean along with increasing water temperatures resulting from global warming will have devastating effects on many species- including many planktons! Furthermore, as plankton populations grow they will eventual transition from CO2 sinks (good) to CO2 emitters (bad). So overfishing has a link to global warming- who knew?
In sum, my guess is that a few years down the road we will again be reading headlines about the pollock fishery in New England-this time again restricting the catch limits. I pray that before this happens we recognize and address the urgent need to cease industrial scale fishing of the planet's most precious resources.
I really enjoyed the post. I think you make some good points. It's important to note too that just as models used to estimate fish populations are subject to flawed assumptions, political pressures, and model misspecification, so too is the predominance of research surrounding "climate change." Your post seems to presuppose global warming while calling the scientific method by which the theory is constructed into question (as that method relates to research on fish populations).
ReplyDelete@Brenton// I guess all science is suspect to some extent. Who would have expected a calling into doubt the existence of gravity?
ReplyDelete(see http://www.nytimes.com/2010/07/13/science/13gravity.html) I think such questioning is good and should be encouraged.
The debate on global warming appears to me more political and economic than scientific at this point. So while over 187 countries signed the Kyoto Protocol that recognized global warming as a global risk, folks are free to question the science of climate change just as I question the science of marine fishery management. In the end though, all we need to concern ourselves with in the marine fisheries context as related to climate change is ocean acidification and increased ocean water temperatures- both of which are indisputable occurring.
Questioning policy and science makes sense yet we must also find sources of guidance if we are to be effective stewards of the planet. In this instance, the effects of denying climate change and overfishing are for more serious and potentially irreversible than ignoring these two potential threats to the world's ecosystems.