Is the bluefin tuna doomed?

Probably. It’s one of the top ocean predators, but it spawns into the water and depends on numbers so that some of its eggs survive mass scavenging by smaller fish. The numbers are dropping while government-subsidizedm, overpopulated fishing industries continue to overfish. And there’s no agreement in sight: “Bad start as European Union rejects fishing quota.”

Europe’s Mediterranean fishing nations have rejected measures to protect the endangered bluefin tuna proposed last month by the European Union fishing chief Maria Damanaki, EU officials said on Thursday…

The total bluefin quota for 2010 was set at 13,500 tonnes and Damanaki said last month that to give the giant fish a real chance of recovery, the 2011 quota should be set at around 6,000 tonnes at the Paris meeting of the International Commission for the Conservation of Atlantic Tunas (ICCAT).

The 10-day ICCAT talks started on Wednesday.

Ms. Damanaki accepted that the need to protect the livelihoods of fishermen would probably dictate a higher quota than 6,000 tonnes. But in a meeting late on Wednesday, EU ambassadors in Brussels, led by France, rebuffed Ms. Damanaki’s proposal and wrote their own, which barely mentions quota reductions.

There’s an appeal and a petition here: “Save the bluefin tuna.” We really can’t afford to destroy the ocean’s ecology. The Japan Sea is seeing ‘blooms’ of giant jellyfish where there aren’t enough fish left to keep their numbers in balance. The jellyfish, in turn, polish off smaller fish and keep the fish stocks from recovering. It’s not a pretty picture!

We need to set a quota and enforce it to stop illegal fishing. The real problem is that no one owns the fish, so everyone can go after them.

Books to read

PZ Myers recommends some basic books about evolution: “Read these!

  • Donald Prothero’s Evolution: What the Fossils Say and Why It Matters(amzn/b&n/abe/pwll)
  • Carl Zimmer’s At the Water’s Edge: Fish with Fingers, Whales with Legs, and How Life Came Ashore but Then Went Back to Sea (amzn/b&n/abe/pwll)
  • Jerry Coyne’s Why Evolution Is True(amzn/b&n/abe/pwll)
  • Neil Shubin’s Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body(amzn/b&n/abe/pwll)
  • Sean Carroll’s The Making of the Fittest: DNA and the Ultimate Forensic Record of Evolution(amzn/b&n/abe/pwll)

This is not an onerous demand. These books are not overly technical, they aren’t part of the specialist literature, they are just general introductions to the ideas and evidence of evolution.”

I’ve read At the Water’s Edge and Your Inner Fish. Both were informative, enjoyable, and convincing as they explained some of the history of evolution. At the Water’s Edge describes the history of tetrapods’ conquest of the land, with the evidence we have. Shubin’s Your Inner Fish shows the traces of our fish ancestry in our bodies.

A major Atlantic cod population heads for extinction

Years after halting the cod fishery, experts are seeing no recovery in the population.

A new study predicts for the first time that a major population of Atlantic cod, near Newfoundland, Canada, will essentially go extinct within 20 years, despite best attempts to manage it. “This is the most shocking and disturbing news I’ve ever heard about a marine fish population,” says fisheries biologist Jeffrey Hutchings of Dalhousie University in Halifax, Canada.

Atlantic cod is a symbol of boom-and-bust commercial fishing. After 50 years of heavy harvesting in the late 20th century, the Canadian cod fishery collapsed in the early 1990s. Total bans ensued, and fisheries managers expected to see a recovery. However, after 15 years of little to no fishing, local populations show no sign of rebounding. In fact, some will continue to spiral downward, according to projections reported in this month’s issue of the Canadian Journal of Fisheries and Aquatic Sciences.

Biologists Douglas Swain and Ghislain Chouinard of Canada’s Department of Fisheries and Oceans used well-established models of fishery stocks to predict the future of the fourth largest population of cod, in the southern Gulf of St. Lawrence, southwest of Newfoundland. The models took into account the population’s productivity, based on the proportion of young fish that mature, the growth of adults, and natural mortality rates. The results were sobering: The southern Gulf cod stock will be extirpated (local extinction defined as less than 0.3% of the species’ original biomass) within 20 years if limited fishing is allowed. Even if the fishery is completely closed, the stock will hit rock bottom in 38 years.

The main problem, according to Swain and Chouinard, is that adult cod have been dying at an unusually high rate in recent years. No one knows why, but Swain suspects the cause might be increased predation by seals. The problem may be more widespread: The neighboring Scotian Shelf cod population also took a nosedive in the 1990s based on data from a Canadian report published in 2003. Furthermore, while most other cod populations off Canada appear to be stable, the same could have been said about the southern Gulf population up until a few years ago, says Swain.

Although biologists have traditionally assumed that stocks will rebound if fishers simply stop fishing, Hutchings notes, the new study of cod is an “extremely compelling example of the fallacy of that assumption.” As for extirpation of a cod population, Hutchings says he never considered it possible until this analysis. However, fisheries biologist Ralph Mayo of the National Oceanic and Atmospheric Administration in Woods Hole, Massachusetts, says the outlook could be better for smaller U.S. cod stocks in the Gulf of Maine and on Georges Bank. “The Gulf of Maine population has even been increasing,” he says. That, of course, is small consolation for Canada.

http://sciencenow.sciencemag.org/cgi/content/full/2008/1125/1

Chinook Salmon population crashes in Sacramento River

Ninety thousand fish showed up last year, a meagre remnant of the population. The commercial salmon fishing season was cancelled for U.S. fisherfolk But who knows what’s going on in international waters? Trawling and other forms of deep-sea fishing have probably taken their toll. A mere 60,000 fish are expected back this year.

Thirty years ago there were several thousand salmon boats in California. More recently, as the fish became scarce, only a few hundred worked the coast. Then salmon populations crashed, and this year for the first time U.S. officials canceled all ocean salmon fishing off California and most of Oregon, and curtailed it off Washington….

The sudden decline of California’s chinooks, most of which originate in the Sacramento River, has shaken scientists as well as fishermen. Typically several hundred thousand adult fish return from the sea to the river in the fall. Last autumn, only about 90,000 made it back, and fewer than 60,000 are expected this year, which would be the lowest number on record….

The sudden decline of California’s chinooks, most of which originate in the Sacramento River, has shaken scientists as well as fishermen. Typically several hundred thousand adult fish return from the sea to the river in the fall. Last autumn, only about 90,000 made it back, and fewer than 60,000 are expected this year, which would be the lowest number on record.

I want one!

…preferably in front of my desk, where I can gaze into the aquarium while organizing my thoughts.

fish tank with modules

fish tank with modules

Zooilogix has a whole collection of unusual fish-tanks.

No fish by 2050?

The world’s fisheries may be practically gone by 2050, according to biological research calculations.

Says lead author Boris Worm, “Whether we looked at tide pools or studies over the entire world’s ocean, we saw the same picture emerging. In losing species we lose the productivity and stability of entire ecosystems.” This sad picture emerged over four years of analyzing 32 controlled experiments, observational studies from 48 marine protected areas, and global catch data from the UN’s Food and Agriculture Organization’s (FAO) database from 1950 to 2003. The scientists also looked at a 1000-year time series for 12 coastal regions, drawing on data from archives, fishery records, sediment cores and archeological data.

Here’s the mathematical projection:

trends in fish populations at 2006

We’re still taking 235,000 tons fish per day from the sea.

Go to Blog of Science to read about the research and its implications. It’s still reversible.

December 22 is Coelacanth Day!


Palaeoblog pointed out on December 22 that it was the anniversary of Marjorie Courtenay-Latimer’s discovery of an extant coelacanth. The fish was a member of the coelacanth family but not in the same species or even genus as all other coelacanth specimens, which were known only from fossils.

See also “Latimer didn’t ‘just happen’ on coelacanth.”

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