[env-trinity] CBB: Humans exploit adult fish populations at 14 times rate of marine predators

[Sari Sommarstrom]

Columbia Basin Bulletin

 


Unsustainable Predators? Humans Exploit Adult Fish Populations At 14 Times
Rate Of Marine Predators 
Posted on Friday, August 28, 2015 (PST) 


Are humans unsustainable 'super predators'?

 

Research published in the journal Science reveals new insight behind
widespread wildlife extinctions, shrinking fish sizes and disruptions to
global food chains.

 

"These are extreme outcomes that non-human predators seldom impose," says
the article titled "The Unique Ecology of Human Predators."

 

"Our wickedly efficient killing technology, global economic systems and
resource management that prioritize short-term benefits to humanity have
given rise to the human super predator," says lead researcher Dr. Chris
Darimont, the Hakai-Raincoast professor of geography at the University of
Victoria, Darimont is also science director for the Raincoast Conservation
Foundation. "Our impacts are as extreme as our behavior and the planet bears
the burden of our predatory dominance."

 

The team's global analysis indicates that humans typically exploit adult
fish populations at 14 times the rate of marine predators. Humans hunt and
kill large land carnivores such as bears, wolves and lions at nine times the
rate that these predatory animals kill each other in the wild.

 

Humanity also departs fundamentally from predation in nature by targeting
adult quarry.

 

"Whereas predators primarily target the juveniles or 'reproductive interest'
of populations, humans draw down the 'reproductive capital' by exploiting
adult prey," says co-author Dr. Tom Reimchen, biology professor at UVic.
Reimchen originally formulated these ideas during long-term research on
freshwater fish and their predators at a remote lake on Haida Gwaii, an
archipelago on the northern coast of British Columbia.

 

The data set includes wildlife, tropical meat and fisheries systems from
every continent and ocean, except Antarctica.

 

The authors conclude with an urgent call to reconsider the concept of
"sustainable exploitation" in wildlife and fisheries management.

 

A truly sustainable model, they argue, would mean cultivating cultural,
economic and institutional change that places limits on human activities to
more closely follow the behavior of natural predators.

 

The full story in Science appears here:
<http://www.sciencemag.org/lookup/doi/10.1126/science.aac4249>
http://www.sciencemag.org/lookup/doi/10.1126/science.aac4249

 

"The Unique Ecology of Human Predators" project, supported by UVic, the
Raincoast Conservation Foundation and the Hakai Institute includes 2,125
estimates of annual finite exploitation rates, drawing on data from more
than 300 studies. Other co-authors include Caroline H. Fox and Heather M.
Bryan of UVic, Raincoast and the Hakai Institute.

 

During four decades of fieldwork on Haida Gwaii, UVic biologist Dr. Tom
Reimchen conceived the idea to look at how human predators differ from other
predators in nature.

 

Reimchen's predator-prey research revealed that predatory fish and diving
birds overwhelmingly killed juvenile forms of freshwater fish. Collectively,
22 predator species took no more than two per cent of the adult fish. 

 

Nearby, Reimchen observed a stark contrast: fisheries exclusively targeted
adult salmon, taking 50 per cent or more of the runs.

 

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