[MARMAM] New publication: Whales sustain fisheries: Blue whales stimulate primary production in the Southern Ocean

Trish Lavery tricia_lavery at yahoo.com.au
Thu May 22 17:14:41 PDT 2014


Dear Colleagues,

We are pleased to announce the release of a new publication in Marine Mammal Science:

Whales sustain fisheries: Blue whales stimulate primary production in the
Southern Ocean.
Trish J. Lavery, Ben
Roudnew, Justin Seymour, James G. Mitchell,
Victor Smetacek, Steve Nicol.
It has previously
been asserted that baleen whales compete with fisheries by consuming
potentially harvestable marine resources. The regularly applied ‘surplus-yield
model’ suggests that whale prey becomes available to fisheries if whales are
removed, and has been presented as a justification for whaling. However, recent
findings indicate that whales enhance ecosystem productivity by defecating iron
that stimulates primary productivity in iron-limited waters. While juvenile
whales and whales that are pregnant or lactating retain iron for growth and
milk production, non-breeding adult whales defecate most of the iron they
consume. Here, we modify the surplus-yield model to incorporate iron
defecation. After modeling a simplistic trajectory of blue whale recovery to
historical abundances, the traditional surplus-yield model predicts that 1011 kg of carbon yr-1 would become unavailable to fisheries. However,
this ignores the nutrient recycling role of whales. Our model suggests the population
of blue whales would defecate 3×106 kg of iron yr-1,
which would stimulate primary production equivalent to that required to support
prey consumption by the blue whale population . Thus, modifying the
surplus-yield model to include iron defecation indicates that blue whales do
not render marine resources unavailable to fisheries. By defecating iron-rich feces,
blue whales promote Southern Ocean productivity, rather than reducing fishery
yields.

Please contact Dr. Trish Lavery for re-prints: tricia_lavery at yahoo.com.au
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