Why Nature Matters: Oceans

“Fishing and fish farming… are headed for a train wreck,” -Jeremy Jackson, a professor of Oceanography at the Scripps Institution of Oceanography in San Diego and a Senior Researcher at the Smithsonian (The Rise of Slime, by Naomi Lubick).

The Rise of Slime

A mass of slime spreads across the ocean floor, sickening the fishermen who come in contact with it.

Elsewhere, fishermen pull in their nets to find them bulging with jellyfish. One fisherman predicts that in 50 years we will have no fish to eat but jellyfish.

These events, like something out of a science fiction novel, are happening right now, and they are chronicled in A Primeval Tide of Toxins, by Kenneth R. Weiss.

The ocean eco – collapse is not a result of one single thing, but of many: overfishing, destruction of habitat, global warming, pollution. Dead zones are created by nutrient runoff from agriculture and runoff. The excess nutrients create prime habitat for plankton – and the plankton exhaust the oxygen supply.

The effects move up the food chain: anchovies and sardines eat the microorganisms. The small fry are in turn eaten by larger marine mammals: sea lions, whales, and dolphins. The large mammals are poisoned by the toxins in the algae, and they beach themselves, or get lost at sea, more and more every year.

Fish and other marine animals must leave the dead zone or die, but Jellyfish thrive on the plankton: another part of the rise of slime.


Jellyfish took over the gulf of Mexico in 2000, and are blooming all over the world. Their weight can stop a 90 foot fishing boat in its tracks and burst fishing nets. They have been known to shut down power plants by clogging water intake pipes.

The rise of jellyfish is also due to climatic shifts, overfishing that removes predators and competitors, and global sea trade, which has brought invasive jellies to parts of the ocean where they can thrive.

A prime example of the havoc wreaked by invasive Jellies is the Comb Jelly invasion of the Black Sea. The Comb Jellies were introduced in 1982 by a US ship dumping its ballast water. They quickly took over, finding few competitors in the heavily fished water. They damaged the local fishing industry to the tune of $350 million before their populations fell prey to another invasive jelly introduced in 1997.

“The Blobs of Summer”, by Lily Whiteman, On Earth Magazine, Summer 2002.

Jellyfish Dominate Fish In Over-harvested Namibian Waters, Sciencedaily.com

Jellyfish Take Over an Overfished Area, by John Nielsen, NPR.org


Overfishing destroys populations directly. Many of the bigger fish, which serve a vital role as predators in the oceans, have been depleted.

As we have overfished the bigger species, fishermen have taken to deep trawling, dragging a deep net that scrapes the bottom of the ocean. This destroys reefs and other habitat. It’s estimated that the amount of ocean habitat destroyed in this way is more than all the forests logged in human history – and coral can take millenia to recover.

See here for lots of interesting (if depressing) graphs and graphics: Ecosystem extinction in the Ocean, a presentation by Jeremy Jackson.


In the Pacific Ocean between Hawaii and the west coast of the US, there is a confluence of ocean currents.

The currents carry plastic litter to an area roughly the size of Texas, posing a serious threat to wildlife.

“Of the 500,000 albatross chicks born here [on the Island of Midway] each year, about 200,000 die, mostly from dehydration or starvation. A two-year study… showed that chicks that died from those causes had twice as much plastic in their stomachs as those that died for other reasons.”Plague of Plastic Chokes the Seas, Kenneth Weiss.

This is a global problem. Greenpeace recently released a study, Plastic Debris in the World’s Oceans detailing the extent of the problem and the hazards.

Global Warming

Habitats shift northward as the tropics warm. Corals are bleach due to increased CO2 in ocean water and higher temperatures, but also due to a variety of other factors: increasing nutrients from runoff and sedimentation, increased solar radiation (ultraviolet light), and changes in ocean salinity.

How Does the Ocean Benefit Humans?

We don’t fully understand all the ways Ocean ecology works. A recent study suggests that Salmon traveling upstream to their spawning grounds carry nutrients from the ocean into the rivers and forests. (
Pacific Salmon and the Ecology of Coastal Ecosystems, Daniel Schindler et al., published in Frontiers in Ecology and the Environment, vol. 1 number 1
) Ocean nutrients have even been found in grapes growing in wineries in the Pacific Northwest, and likely contribute to their growth.


1 billion people worldwide rely on fish as their primary source of protein.

The global fish trade accounted for 58 billion dollars in exports in 2002. (Earth Policy Institute: Wild Fish Catch Hits Limits, 2005 by Janet Larsen)

The countries that rely most on fishing are the developing countries. “In 1990, 95% of the world fishers and fish farmers were from developing countries and they produced 58% of the 98 million tons of world fish.” (p. 3, Number of Fishers Doubled since 1970, FAO) Much of this catch goes to developing countries, and this trade is a valuable component of developing economies. “Fish is the most important foreign exchange earner among all agriculture products traded by developing countries.” (p. 11, World Fish Trade, FAO, Helga Josupeit Helga Josupeit, 2003)

Worldwide, more and more people are employed in fishing. Fishing industry jobs doubled from 1970 to 1990, and continued to boom in the 1990’s, yet wild fish catches have leveled off in the past 20 years, even declined.

Other economic effects are harder to quantify: tourism at beaches and coral reefs, sport fishing, and boating activities, etc. I’ll offer one example. A recent study estimated the annual gross revenues in the state of California from the sport of SCUBA diving to be between $138 million and $276 million. They estimated snorkeling to bring in somewhere between $153 million to $344 million every year in California.

That money supports dive masters, dive shops, destinations, local hotels and restaurants, charter boat captains and crews, and a host of other services. (Understanding the Potential Economic Impact of SCUBA Diving and Snorkeling: California, by Linwood Pendleton and Jaime Rook, University of California, 2006)


Fish farming is rising rapidly as wild fish catches decline. This could be good news, if it is managed properly.

For one thing, monoculture, that is, a mass of the same species of fish, is more vulnerable to disease than wild fish. There have already been examples of sea lice from farmed salmon killing wild salmon.

The other thing is, aquaculture must come to replace wild fishing, not supplement it, if we are to preserve ocean ecology for future generations.

Ecological collapse in the oceans poses a global problem with no easy solutions. Illegal fishing occurs on the high seas, which are often not regulated by international agreements. (see New Estimates of the Shark Fin Trade by Janet Raloff for an example of illegal and unregulated practices.) Litter is carried by ocean currents far from its origin, and global warming affects us all.

Hard decisions will have to be made, and soon, or we might indeed find ourselves sickened by the changing oceans, (Dark Tides, Ill Winds, by Kenneth R. Weiss) eating jellyfish and remembering the good old days.


2 responses to “Why Nature Matters: Oceans

  1. After seeing a depressing video from Jeremy Jackson on the dismal state of our oceans, I went Googling. I found no counter arguments to his theories , observations, prounouncments, and graphs. This, in itself, is not bad but to me, a little worrisome. Am I alone here? Science is not about agreement, necessarily. I am suspicious of old Greenpeacers with ponytails–no matter how shiny their credentials.

  2. Phil,

    Honestly I’ve not looked for any counter arguments to Jackson. You’re obviously a bit of a skeptic, which is not really a bad thing. But if you can’t find anything to counter an argument, it seems to me that you would accept that argument. Do you accept that the oceans are in a sorry state or not? Or are you lamenting the fact that there are no other views about the state of the oceans?

    I’d be open to data that showed that the oceans were doing just fine – I’d be very happy about it in fact. But it seems to be something we should all be worried about regardless of our political stance or skepticism/suspicion of enviromentalists.

    I’m just trying to get a better idea of your perspective on this. I’ve had discussions with many people who are skeptical of various environmental issues. Skepticism is healthy… I’m a bit of a skeptic on global warming in fact, (although I think the balance of evidence supports the idea that humans are causing it) but I do strongly believe that the biosphere as a whole is in serious deep doo doo and humans will face big problems because of it.

    So can you clarify a little – are you simply suspicious of Jackson because he’s an enviro or because you have reason to believe his science is wrong?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s