Tag: fish

Let Them Run

From Conservation Magazine, a nice little article on our recent paper in Conservation Letters calling for a small number of fully protected salmon runs.

Ask not what a park can do for spawning salmon. Ask what robust salmon runs could do for the park – and for coastal fishing communities.

That’s the provocative idea behind a “radical” proposal being floated by a group of conservation biologists. Limiting fishing for some pink and chum salmon bound for spawning streams in British Columbia parks could reinvigorate ecosystems that thrive on the annual infusion of millions of fish carcasses. And, in the long run, protecting the runs could produce economic benefits by making ecosystems more productive and resilient to change.

“Although managers safeguard protected areas for migratory species, little consideration has been given to how migratory species might benefit parks,” a team led by Chris Darimont of the University of California, Santa Cruz, and the Raincoast Conservation Foundation in Canada write in Conservation Letters. Case in point: Headwaters streams in coastal parks in British Columbia once saw huge annual runs of Pacific salmon. Many of the spawned-out fish died, producing a “fertilizer effect” that pumped a vast pulse of nutrients into surrounding ecosystems. “The breakdown of salmon carcasses…  ultimately can affect communities of riparian plants, terrestrial and freshwater invertebrates, resident fish, and songbirds,” the authors note. These days, however, commercial and recreational fishers kill up to 90% of the fish before they can spawn, blocking the transfer of nutrients.

To restore at least part of that pulse, the authors propose limiting catches of pink and chum salmon(Oncorhynchus gorbuscha and keta), which have still have large runs but low commercial value. While Chinook salmon sold for $1.23 a pound in 2002, for instance, pink and chum sold for just 6 to 16 cents a pound. “We believe that a focus on pink and chum… provides opportunity to implement our ideas without severe economic consequences.”

The authors concede that “some might deem our idea politically unachievable,” but add that their “aim is to inform and inspire decision-makers with a plan that not only favors biodiversity but also one that ultimately might yield economic and management benefits. Our goal is to inoculate the literature with a provocative idea to stimulate discussion.”

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Human-Driven Evolution

From Science Friday on NPR, Chris Darimont discusses our recent PNAS paper on human-driven evolution.  Listen to the full radio spot here.

Can humans angling for the prize-winning fish shift the course of evolution? Research published this week in the Proceedings of the National Academy of Sciences says that predation by humans through hunting, fishing, and gathering has had significant influences on the rate of evolutionary change in a wide variety of species. Traits such as body size and first reproductive age shift significantly in species that are ‘harvested,’ the authors say.

“Fishing regulations often prescribe the taking of larger fish, and the same often applies to hunting regulations,” said Chris Darimont, one of the authors of the study. “Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we’re seeing the consequences of this management.” Darimont and colleagues found that human predation accelerated the rate of observable trait changes in a species by 300 percent above the pace observed within purely natural systems, and 50 percent above that of systems subject to other human influences, such as pollution,. We’ll talk with Darimont about the team’s findings.

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Research Ties Human Acts to Harmful Rates of Species Evolution

From the NY Times, a Science Times article on our recent PNAS paper.

Human actions are increasing the rate of evolutionary change in plants and animals in ways that may hurt their long-term prospects for survival, scientists are reporting.

Hunting, commercial fishing and some conservation regulations, like minimum size limits on fish, may all work against species health.

The idea that target species evolve in response to predation is not new. For example, researchers reported several years ago that after decades of heavy fishing, Atlantic cod had evolved to reproduce at younger ages and smaller sizes.

The new findings are more sweeping. Based on an analysis of earlier studies of 29 species — mostly fish, but also a few animals and plants like bighorn sheep and ginseng — researchers from several Canadian and American universities found that rates of evolutionary change were three times higher in species subject to “harvest selection” than in other species. Writing in The Proceedings of the National Academy of Sciences, the researchers saythe data they analyzed suggested that size at reproductive maturity in the species under pressure had shrunk in 30 years or so by 20 percent, and that organisms were reaching reproductive age about 25 percent sooner.

Click here to read the full article at nytimes.com.

 

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The Fastest Way to Change a Species: Start Eating It

From Science magazine, more coverage on our PNAS article.

From the dwindling Atlantic cod to the increasingly rare American ginseng plant, species are racing to adjust to relentless human exploitation. According to a new analysis, the rate at which hunted and harvested species are changing their size and breeding schedules is unmatched in natural systems. Ecologists say the results point to errors in the way we manage fisheries and other harvested populations.

Researchers have noted rapid changes in heavily exploited fish and other species since the 1970s. To name one famous example, adult Atlantic cod (Gadus morhua) have decreased 20% in size over the past 30 years, and females now reproduce a year earlier than they used to (ScienceNOW, 31 January 2007). Although such hunting-induced alterations seem rapid, evolutionary biologist Chris Darimont of the University of Victoria in Canada, and colleagues wanted to determine whether they outpace changes in nonharvested organisms.

Read the full article here.

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