Basically, we are going through a phase transition, between a state where there were few monkeys to one where there are many monkeys. This means the former time where issues are distinct and perhaps have tenuous connections is over; now there is one big tangled problem: how do we keep the monkeys happy while settling them down and training them to live in a more or less zero-sum situation.
Maribo (H/T Stoat) offers us this daunting image to bring home one slice of the problem:
and a recent article in the online Journal PlosOne goes further.In Ecosystem Overfishing in the Ocean by the Spanish, Canadian and Italian collaboration of Marta Coll, Simone Libralato, Sergi Tudela, Isabel Palomera, and Fabio Pranovi, the overfishing problem is viewed as a bulk biogeochemical process.
Here's the abstract:
Fisheries catches represent a net export of mass and energy that can no longer be used by trophic levels higher than those fished. Thus, exploitation implies a depletion of secondary production of higher trophic levels (here the production of mass and energy by herbivores and carnivores in the ecosystem) due to the removal of prey. The depletion of secondary production due to the export of biomass and energy through catches was recently formulated as a proxy for evaluating the ecosystem impacts of fishing–i.e., the level of ecosystem overfishing. Here we evaluate the historical and current risk of ecosystem overfishing at a global scale by quantifying the depletion of secondary production using the best available fisheries and ecological data (i.e., catch and primary production). Our results highlight an increasing trend in the number of unsustainable fisheries (i.e., an increase in the risk of ecosystem overfishing) from the 1950s to the 2000s, and illustrate the worldwide geographic expansion of overfishing. These results enable to assess when and where fishing became unsustainable at the ecosystem level. At present, total catch per capita from Large Marine Ecosystems is at least twice the value estimated to ensure fishing at moderate sustainable levels.In other words:
Fisheries catches represent a net export of mass and energy that can no longer be used by trophic levels higher than those fished. Thus, exploitation implies a depletion of secondary production of higher trophic levels due to the removal of prey. Based on this assumption, a new method was developed to quantify the loss in secondary production (L index) due to the removal of marine organisms through catches (expressed as PPR equivalents) compared to a theoretical unfished situation...Humans aren't just overfishing species, we are exporting biomass, degrading it, and pooping it back out into estuaries to first order. We are clear-cutting the whole ocean.
Again, the incentives for individual ship owners to behave this way are clear enough. The question is how to remove those incentives when the catch becomes too large, which it clearly is. I don't know; cap and trade is hard enough to enforce on nations, never mind on boats. And maybe, since we're going to acidify the oceans beyond supporting advanced life anyway, it could be argued that we might as well go ahead and send boats to pick out all the nice sushi first.
The sorts of decisions that have to be made to preserve the entire ocean are without precedent. It is a good thing that scientists go out and try to keep us informed as to what is happening. It would be better if there were some way to reward people for coming up with ways to change our collective behavior.
Update: Here's some perverse incentives for you, in a video clip sent by "tidal".
We already "clear cut" the oceans, now we are going back and salvaging the stumps and trash that we left on the fist pass.
ReplyDeleteOne point that is often ignored is that plastic trash in the ocean affects the productivity. A fish with a belly full of plastic dies. And any fish that eats that dead fish now has a belly full of plastic.
This mildly surprises me, because my limited understanding of overfishing is that we tend to do the assault by working do down the trophic levels - i.e. devastate the large predators first (cod, salmon, tuna, etc.) and then turn the guns on the smaller fish, etc. (Of course, no reason not to both at the same time! Is this not absolutely appalling footage?)
ReplyDeleteAlthough that always seemed like an overly simplistic narrative, given the widespread destruction we are causing across the entire marine ecosystem. In this fascinating - and depressing - talk (and the paper that developed from it), Jeremy Jackson seems to be taking a much wider perspective, like these authors.
While I am posting links, the UNEP report from earlier this year, "In Dead Water", is a keeper as well.
And, circling back to the large predators, Carl Safina on bluefin tuna last week: After years of inaction and continuous decline, letting them spawn free of constant harassment and giving the populations a five-year cease-fire seems the only hope for saving the giant fish. The "International Conspiracy to Catch All the Tuna", hehehehe... except it's not funny.
Correcting the url for the highlighted "widespread destruction we are causing across the entire marine ecosystem" in the post above.
ReplyDeleteIn my view an easy thing to do is pay the fishermen not to fish - to let their fields lay fallow, if you will.
ReplyDeletePay the paper on their equipment for, say, 7 years, pay their salaries, and give them a tax break to go to school. Much cheaper in the long run. But then again, how often do we ever think of the long run? Small Asian fishermen, well, that's another issue.
Best,
D
You know, this is an important article, if we can translate it up to decision-makers that actually can do something (per my pvs comment).
ReplyDeleteThis figure 4, for example. Look at the long upward slope ending about when the Green Revolution finally hit big.
This is a very simple figure to translate (as is the worldwide grain production per capita).
This and grain production say the same thing: we no longer can feed everybody forever on this trajectory. We must do something else.
Best,
D