Two short articles here, the one following this is an interesting letter by a scientist on the environmental interconnectedness of the many 'big ideas' we undertake for 'economic' reasons -well worth reading.
Re the adjacent article here -related, it can be argued that virtually all of the various problems associated with environmental integrity today -human well-being therein, would not exist if we had not more or less 'circumstantially and ignorantly
proliferated and diasporated like the merely warm-blooded cerebrating vertebrates of our origins'.
perryb
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4 Minutes Audio on Continuing Human Existence
News of the Week
ECOLOGY:
Parasites From Fish Farms Driving Wild Salmon to Extinction
Erik Stokstad
A new study suggests that fish farming could rapidly wipe out some populations of wild salmon in British Columbia. Although some researchers are calling for dramatic controls on the industry, others say the risk hasn't been established firmly enough. At
stake is the $450 million aquaculture business.
One of the top concerns about aquaculture is the spread of disease and parasites to wild species. On page 1772, the first population-level analysis suggests that sea lice from farmed salmon will cause several populations of one species
of salmon in British Columbia to plummet by 99% within 8 years. "It's a shocking number," says salmon conservation expert John Reynolds of Simon Fraser University in Burnaby, Canada, who was not involved in the research. But environmental physiologist
Scott McKinley of the University of British Columbia in Vancouver worries about rushing to judgment. "You cannot conclude anything from a correlation," he says.
CREDIT: M. KRKOŠEK ET AL., SCIENCE
Sea lice are small crustaceans that latch onto salmon and other fish. They feed on tissue and create lesions that make it hard for fish to regulate their body fluids. The saltwater parasites naturally occur on adult salmon in the sea but not on juveniles, which hatch in fresh water and then swim to the sea. In 2001, however, researchers found significant numbers of sea lice on wild juveniles that had passed by fish farms in British Columbia. The situation was alarming because young pink salmon are more vulnerable to damage from lice than adult salmon are.
Graduate student Martin Krkošek of the University of Alberta, Edmonton, started studying the problem in 2003. In previous papers, he and colleagues calculated that juvenile pink salmon are 73 times more likely to be infected with sea lice after they passed by salmon farms than are fish that didn't pass by and that lice can kill between 9% and 95% of juvenile pink salmon, depending on how many fish farms they must swim by. Some researchers are unconvinced, however, and point to other studies that suggest lower mortality from sea lice.
In the new work, Krkošek and colleagues investigated the extent to which sea lice are affecting pink salmon populations throughout the Broughton Archipelago near Vancouver Island. They analyzed 35 years of records from the Canadian fisheries agency on the number of salmon in seven rivers that flow into marine channels with fish farms. They also looked at 64 rivers from which migrating salmon do not pass by fish farms. Using a standard model, they calculated that pink salmon not exposed to fish farms showed the same range of population size for all 35 years, varying from year to year.
The pink salmon that swam past salmon farms showed the same pattern, until the lice infestations began in 2001. Then all seven populations shrank year after year. If these populations continue to decline at this rate, they will be 99% gone within four generations. "It's very fast," says Krkošek, who says immediate conservation steps are necessary. "We can't sit around and do more research, because these fish will be gone." Senior author Mark Lewis of the University of Alberta in Edmonton and another co-author were among 18 scientists who in September called for requiring salmon farms to be surrounded by barriers to prevent the spread of parasites or disease.
As with previous papers, the reaction to the new finding is polarized. McKinley and others say that there are too many unknowns to conclude that sea lice from farms harm wild salmon. Many factors influence their abundance, including fluctuations in ocean nutrients. But fisheries biologist Ray Hilborn of the University of Washington, Seattle, says it is too risky to farm fish in open pens near wild relatives: "The bigger concern is that [sea lice] are just one of many pathogens. There could be other things out there that we don't know about."
Science 14 December 2007:
Letters
Switch to Corn Promotes Amazon Deforestation
The United States is the world's leading producer of soy. however, many u.s. farmers are shifting from soy to corn (maize) in order to qualify for generous government subsidies intended to promote biofuel production (1); since 2006, U.S. corn production
has risen 19% while soy production has fallen by 15% (2). This in turn is helping to drive a major increase in global soy prices (3), which have nearly doubled in the past 14 months.
The rising price for soy has important consequences for Amazonian forests and savanna-woodlands (4). In Brazil, the world's second-leading soy producer, deforestation rates (5) and especially fire incidence (6) have increased sharply in
recent months in the main soy- and beef-producing states in Amazonia (and not in states with little soy production). Although dry weather is a contributing factor, these increases are widely attributed to rising soy and beef prices (5, 7), and studies
suggest a strong link between Amazonian deforestation and soy demand (8, 9).
Some Amazonian forests are directly cleared for soy farms (8). Farmers also purchase large expanses of cattle pasture for soy production, effectively pushing the ranchers farther into the Amazonian frontier or onto lands unsuitable for
soy production (9). In addition, higher soy costs tend to raise global beef prices because soy-based livestock feeds become more expensive (10), creating an indirect incentive for forest conversion to pasture. Finally, the powerful Brazilian soy lobby is
a key driving force behind initiatives to expand Amazonian highways and transportation networks in order to transport soybeans to market, and this is greatly increasing access to forests for ranchers, loggers, and land speculators (11, 12).
In a globalized world, the impacts of local decisions about crop preferences can have far-reaching implications. As illustrated by an apparent "corn connection" to Amazonian deforestation, the environmental benefits of corn-based
biofuel might be considerably reduced when its full and indirect costs are considered.
William F. Laurance
Smithsonian Tropical Research Institute
Apartado 0843-03092, Balboa, Ancón, Panama
