|I took this image from the Vegetarian Network of Victoria's site (http://www.vnv.org.au/Articles/Fish.htm)|
Here is an article on the site Science Daily called Using Fish Caught as Measure of Fisheries Health is Misleading. It actually recounts a point/counterpoint editorial that apparently appeared in this week's issue of the journal Nature.
Although the article is correct in that there needs to be a great investment by all countries to seriously and scientifically count marine populations, I also feel it misses a lot of the key reasons as to why that is the case. In fact, it only points out the ways in which reliance on catch levels to determine population makes us believe that there are fewer fish left than there really are, and not the many ways that using those numbers makes us think there are more fish left than there really are. In other words, it biases readers into believing that everything is fine and good in the world's seas and there are still plenty of fish in them. In my opinion, it is dangerous to this planet to spread that false message, even if it's done in the subtle (and somewhat confusing) way this article does it.
The point/counterpoint seems to be set up like this: Daniel Pauly says that catch numbers are a good measure of fish populations, while Ray Hilborn and Trevor Branch believe that catch numbers are a bad measure of fish populations because it makes the population of fish seem lower than it actually is. But what about a viewpoint that explains how catch numbers make people think that fish populations are higher than they actually are? Granted, I cannot read the original Nature article without paying over $30, but that's how the Science Daily article describes it.
Fishing vessels often will catch fish that they are not allowed to bring to shore due to fishing limits, so they'll simply throw them back in the water, dead or dying from the change in pressure or from the time out-of-water. On one hand, that means that there are more of those fish in the sea than we're counting, because only what is brought to shore is counted, so we may think the populations are lower than they really are. On the other hand, it means that far more fish are being caught and killed than are being counted.
I have to assume that when scientists base a population count off of a catch count, they take catch limits into account, and add more to the projected population of that particular fish, since, obviously, fishers are only not catching those fish because they're not allowed to, not because those fish aren't there to be caught. That's just common sense. If they are adding numbers to counts based on catch to adjust for effect of catch limits, then the population projections are inaccurately high -- that is, far more fish are being killed than we're counting. But if they're not adding numbers to the population projections because of catch limits, as this article implies, then the numbers may be somewhat close to the truth. Counters may think from lower catches that there are fewer fish, and there actually are fewer fish because they were caught and released dead, so it might even itself out.
Obviously, this is a crazy way to count fish populations, and more accurate ways are necessary, as the article concludes, although they conclude it for misleading reasons.
One of the many vital reforms that must be made to preserve marine populations is that nothing should ever be thrown back dead and dying. Every fish that is captured should be brought to shore and counted. The point of catch limits is to prevent extinction of the fish being caught. That's important, and there should certainly be catch limits. But those limits are meaningless if it only causes fishers to allow killed fish to go uncounted. To have more accurate numbers, all fish caught should be legally required to be brought to shore and part of the count.
The article also fails to mention that fishing methods have become so high-tech that numbers have been able to stay the same, decrease only slightly, or even increase, despite lower populations. Fish have nowhere to hide anymore. Now, fishers use radar to locate groups of fish and go after them. Obviously, this is not a sustainable practice, and it needs to be outlawed immediately. These high-tech methods distort the catch numbers by making people believe that fish are plentiful because we're still catching high numbers of them. But make no mistake, we're catching the last of them.
Hilborn and Branch claim that "fishers might choose to fish less when the price of fish is low and the price of fuel is high," which, in their view, means that fish counts are higher than we're projecting. But let's think about that for a moment. This basically says that the fish are so few that it's impossible to catch enough to make the fuel profitable. As far as this claim that the price of fish is "too low," I have not been able to locate any confirmation of there being wild fish that go for such a low price that fishers are not catching them despite them being plentiful. I've read about fish farmers complaining that the price of fish is too low for their production costs and I've read articles from the early and mid-1900's about fishers switching to the destructive trawling method in order catch more fish because the cost of fish was too low to pay crews without bringing in more fish. But nowadays? I read about fish literally every day and have not encountered a story about low-cost wild marine life, with the exception of complaints about the dropping price of lobsters, which happened because we killed off all their predator fish, so their population increased (meanwhile, the price of the small wild fish used as bait has increased, due to their overfishing).
Ultimately, the article is correct in that there needs to be a great investment by countries to seriously count marine populations. It's difficult because there are so few fish now, and it's hard to count something that's hard to find because it's not there. Still, this needs to be done so that people cannot continue in their denial about the rapidly decreasing biodiversity of the sea, which is due mainly to fishing (and the destruction of ocean habitats from destructive fishing methods) and secondarily because of environmental changes.