Slashdot Mirror
Sharks in Serious Danger
jd writes "According to the BBC, shark populations in the Atlantic declined on average 75% (the hammerhead faring worst at 86% loss) in the past 15 years. This ain't trivial. Many sharks produce one pup a year, if that, and less than half of those survive to adulthood. Sharks are essential to the health of the oceans, so this is not a trivial concern. They're mostly in decline because some idiots like to cut off the dorsal fin, to make soup. (You kill a lot of sharks, and get gristle stew as a reward.) Others die because of paranoia, and yet more because of psychotic trophy hunters. If sharks do die out, they will be the longest-lived species that humanity has exterminated. (Who needs Daleks? We're doing just fine on our own... :()"
Does it matter -- and I'm not being contentious -- how much of the animal we eat, where is the point that we're destroying the population? A dead shark is a dead shark.
... and then the fishery collapsed. Completely, a cliff, not a gradual decline. It shows how things make not wrok intuitively, and after you pass a certain point simply easing off on the take won't fix it.
There is an aesthetic thing to it, this efficiency business, and it makes sense only if the result is that we kill fewer animals (or sharks) and, most of all, don't destroy the population.
There is a wonder chart at the Monterery Aquarium in California, showing the haul of sardines year after year in 40's (or so). Every year the catch grew
I know this was modded as flamebait, because, well...it is flamebait. But it does raise an interesting issue.
Fitness is a measure of average reproductive success. If these shark populations are in fact markedly declining then, yes, these sharks do not seem to be very fit. Fitness is a function of environment. You might say that an individual shark has an particular fitness per particular environmental state. When environments (here defined as including other organisms (including us and other sharks)) change, fitness can change.
However, even if this statement might be more or less factual, this statement was used to say something else entirely: that it doesn't matter, ethically or practically, that sharks are dying out...because well its how the natural world works.
But this is a rather weak arguement. First, physical facts, alone, probably do not unambiguously indicate ethical values. This is known as the fact-value distinction. This means that the fact that sharks are not currently fit does not justify our unconcern for their lack of fitness. Still, it does not indicate the contrary either. Personally, I think that it is a very complicated ethical problem. I think we should beware a tendency towards thinking in terms of "presevation" rather than "stewardship." Just because something is natural, doesn't imply that it is the best of possibilities.
Regardless of the ethics of sharks survival or (non-survival), the decline of shark populations should concern us for other, very pragmatic, reasons. The world's ecosystem is vastly dynamic and inter-connected. 9999999 Changes in one component of the system could have complex, unpredictable, and sometimes dramatic global effects. The world is not so simple as we like to believe. It actually doesn't take much to push a system into a positive feed-back loop that reinfoces some tendency...say an ice-age. And for those who pooh pooh this as some kind of paranoid catastrophism need to take a little closer look at the earth's history (or a look at most of the other planets in our solar system). It is not unusual. It happens all the time.
Logic, macros, and more