Conservation of Biodiversity

Why is overfishing a problem?
Answered by Julie Packard and Daniel Pauly
  • Julie Packard

    Julie Packard

  • Daniel Pauly

    Daniel Pauly

  1. Julie Packard Executive Director, Monterey Bay Aquarium


    The global fishing picture is not a pretty one. Interestingly, in the past couple of years, the past years, there have been several seminal articles published by teams of scientists trying to really get a grip on what is the state of overfishing. In a certain sense in my mind, we can argue about whether 30 percent of global fish stocks are overfished or 70 percent. The point is it's not a good story.

    There is still a lot of debate about what the number really is, but globally speaking, a big percentage, we're going to say maybe -- I would say the average estimate's maybe 50 percent of global fish stocks are being fished beyond their sustainable level. More importantly, there's huge numbers of fish stocks for which we have no data. So a lot of those studies that we see out there are saying how global overfishing is going on at a rampant pace, actually it's only been based on data for fisheries for which we have the information.

    There's a huge need for information. But that being said, in general, the industrialized nations have fairly effective fisheries management laws in place, and even though we've overfished many of our stocks, including here in the U.S., right now, with protections in place, things are starting to recover for nations like the U.S., Australia, New Zealand, very progressive, E.U. nations. Especially in southern Europe overfishing is rampant, very dire circumstance. There's a huge expansion of fishing activity going on, largely out of Asia, a huge ramp-up.

    So, I guess the snapshot would be the situation is pretty dire, and there's a huge lack of information to really tell the full picture.

    All of that being said, there's some obvious interventions that we know need to happen that we're slowly working on. One is there's been a huge capitalization of the global fishing fleets. There's a lot more large-scale boats out fishing. A lot of that's not only extracting fish from the ocean, it's also taking a huge toll on the habitat. We all hear about trawling. Something like the size of the continental U.S. is trawled on the ocean floor every year. It's a vast amount of damage going on from trawling.

    Some nations are putting in place trawling bans on sensitive fish habitats. Here in the U.S., here in California, in fact, California waters we've done a lot of work on that. A lot of the conservations groups have made some great progress, so that's positive. A huge amount of illegal and unreported fishing. That's something that really the science community and conservation community needs to get a grip on and work on reducing global fishing subsidies and reducing illegal or unreported fish.

    In the big scheme of things, what does this mean for our ecosystems? We love to eat the top predators in the ocean, the tunas especially and the swordfish, the big fish. We're fishing those out. The extraction of the top predators from these ecosystems is having a huge toll. It's altering the ecosystems and how they function. But also as we fish those fish out, we're fishing down the food chain, as Daniel Pauly likes to say, and there's now growing fisheries on species that no longer were of particular commercial interest.

    We also have a huge number of small-scale fisheries in developing nations, which usually aren't part of these assessments, it's hard to assess the impact of that, and that really needs to be put into the picture.

    In general, I would say in the industrialized countries, fishing laws are on a positive trajectory in terms of putting protections in place. For some of these fish stocks, say, here on the coast of North America, right here in California, one of the main fisheries that's been closed for a while is rockfish. We have 70 species of what we call rockfish. If you eat them in a restaurant, they're sometimes called snapper, but that's different from the red snapper of the east coast.

    These fish, some of them can live to be 150 years old, which means they don't breed until they're often decades old. Rebuilding some of the species of these rockfish, we're talking a 70- or 80-year recovery trajectory. So the overfishing that we've done in our oceans, it's going to take a long time for the stocks to rebuild.

    I think that one of the biggest challenges is just figuring out how to, if you will, how to right-size our fishing effort. How to get rid of the destructive fishing methods that we use that cause habitat loss, bycatch of endangered species and all that, but also to figure out what level of fishing effort is going to work where people can have a livelihood. Fishing communities, say here in the U.S., can make it.

    Obviously, there's a huge food security issue in developing countries. Here in the U.S., fish is sort of a luxury item, if you will. It's not necessarily an essential part of everyone's diet. It's a big piece to the economy in many of our coastal communities, and we want to attend to that. But in many places, it's, by some estimates, the primary protein for a couple of billion people on Earth. So that's huge. We've got to figure that out.

    More answers from Julie Packard »

  2. Daniel Pauly Professor of Fisheries and Zoology, The University of British Columbia


    You can demonstrate what happens in certain situations where you have almost laboratory-like conditions. For example, in the Baltic, there is the low salinity that prevents lots of species from occurring there. So there is cod, there is some sort of little sardine-like fish -- it's called a sprat -- that eats zooplankton, and little animals like this that eat algae.

    Now, the cod was fished down. For that reason, there are lots of sardines, sprat they're called, and they have eaten up all the zooplankton. The algae don't get cropped, and they have simply filled the Baltic. The Baltic, the water is very turbid; you cannot see anything. And there are harmful algal blooms all the time.

    So in the microscope, well, it's actually a microcosm, but in a smaller area with reduced number of species, you can see what happens. If you remove the big fish, all kinds of nasty stuff can happen. Globally, I have a student who is actually going to defend his thesis in just a week that has demonstrated that in the world altogether, the jellyfish are increasing. There is account of increases everywhere, but this was done systematically to take account of variability.

    More answers from Daniel Pauly »

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