Science - USA (2019-01-18)

graphic variables as well, such as tempera-

ture, currents, and plankton, to see whether

they can be used to predict krill abundance.

IMR will also test remote devices that

could gather krill data continuously and

more cheaply. The Haakon will deploy

moored sensors, as well as wave gliders and

a sail-propelled buoy, in order to compare

their readings with the net and echosounder

data. “This is one of the most beneficial parts

of the survey,” says Bettina Meyer, a krill eco-

physiologist at the Alfred Wegener Institute

in Bremerhaven, Germany.

At the same time, land-based teams from

IMR and the Norwegian Polar Institute will

track seals, whales, and penguins foraging

for krill in the Bransfield Strait, an im-

portant feeding ground near the Antarctic

Peninsula. Matching their feeding behavior

with survey results “has big potential to get

a better idea of the interactions between

the krill fisheries and the predators,” says

So Kawaguchi, a marine ecologist with the

Australian Antarctic Division in Kingston.

The survey itself won’t be able to reveal

how the overall krill population in the

Scotia Sea might have changed since the

2000 survey, given the variability of krill

populations over space and time. Finding

out what drives population changes will

require more research on the seasonal

movement of krill, for example, and the

impact of climate change. Loss of sea ice,

which protects young krill from predators,

is expected to reduce their abundance, and

rising water temperatures and acidifica-

tion could also pose serious threats—ones

that even the best management plan might

not avert. j

SCIENCE sciencemag.org 18 JANUARY 2019 • VOL 363 ISSUE 6424 217

CREDITS: (PHOTO) AUSCAPE INTERNATIONAL PTY LTD/ALAMY STOCK PHOTO; (MAP) A. CUADRA/

SCIENCE

; (DATA) INSTITUTE OF MARINE RESEARCH

K

rill, crustaceans smaller than a ciga-

rette, play an outsize role in the eco-

logy of the ocean around Antarctica:

Penguins, whales, and other preda-

tors feast on vast swarms of the

shrimplike animals. Now, research-

ers have launched a broad international

survey of krill’s main

habitat in and around

the Scotia Sea—the first

in nearly 20 years—to

learn whether a growing

fishing industry is leav-

ing enough for krill’s

natural predators.

The effort, led by

the Institute of Marine

Research (IMR) in Ber-

gen, Norway, began in

earnest last week when

Norway’s new polar re-

search vessel Kronprins Haakon sailed

from Punta Arenas, Chile, for the Scotia Sea.

It and five other vessels will spend nearly

2 months mapping krill abundance across

an area about the size of Mexico. Beside

gauging population, the project will test

tools for cheaper, more frequent surveys

that could improve oversight of the fishery.

“With a more dynamic management sys-

tem, we can be more certain that the fishery

is not negatively affecting the krill popula-

tions or the predators,” says Bjørn Krafft, a

marine biologist at IMR who is directing

the $5 million Norwegian cruise.

Soviet vessels were the first to ply

the Southern Ocean for krill, which was

ground into fish meal. By the 1980s, sci-

entists began to worry about the effect on

krill-feeding predators. The Convention for

the Conservation of Antarctic Marine Liv-

ing Resources (CCAMLR), a treaty organi-

zation established in 1982, set tight limits

on fishing, now at 620,000 tons per year.

Most fishing stopped after the 1991 col-

lapse of the Soviet Union, but it has been

slowly growing again. Norway takes about

half the current catch, extracting omega-

fatty acids for nutritional supplements.

“We absolutely need to know whether

the catch limit is still precautionary,” says

Simeon Hill, an ecologist with the British

Health of stock is critical to fishery—and to predators

OCEANS

By Erik Stokstad

South

Atlantic

Ocean

Scotia Sea

South Georgia

Island

South Sandwich

Islands

Sampling stations

Falkland

Islands

Ship echosounder transects

0 400

Km

Casting a wide net

To estimate abundance of krill, a keystone species, six ships will use echosounders

and focus sampling around fishing hot spots.

Antarctic Survey in Cambridge, who is not

involved in the project.

CCAMLR organized the previous large

krill survey, in 2000. The central finding—

about 60 million tons of krill in the Scotia

Sea—reassured managers that they had been

adequately conservative. But much smaller

surveys, conducted annually in a few places,

have shown that regional krill populations

go through boom and

bust cycles, making it

harder to gauge the

health of the overall

stock from a single sur-

vey. “We have pieces,

but we are missing the

big picture,” says ma-

rine biologist Rodolfo

Werner, an adviser to

the Pew Charitable

Trusts and the Ant-

arctic and Southern

Ocean Coalition, who

is based in Bariloche, Argentina.

During the survey, vessels will retrace the

previous transects, measuring krill swarms

with echosounders, a kind of sonar, and

confirming the identification with sampling

trawls. Some ships will measure oceano-

Flotilla launches large survey

of Antarctic krill

Krill feed on phytoplankton and are a critical

part of the food web.

Area in

detail

NEWS | IN DEPTH

Published by AAAS

on January 17, 2019^

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