Living Blue Planet Report

Chapter 1: The state of our blue planet page 21

Climate change and krill

Krill are vulnerable to impacts associated with climate change:

• Sea ice provides shelter for Antarctic krill during the winter.
  The ice also acts as habitat for algae, which the krill feed on
  (ACE, 2009).


• Krill are a coldwater species and grow fastest in cold water
  — any warming can slow down or stop growth
  (Hill et al., 2013).


• Increased global CO 2 levels in the atmosphere have increased
  the amount of CO 2 absorbed by the ocean, resulting in
  seawater that is more acidic. This is a major threat to krill
  because it can damage their exoskeleton and may cause
  substantial declines in Southern Ocean krill populations over
  the next 100 years (Kawaguchi et al., 2013).

0

1976 1979 1982 1985 1989 1991 1994 1997 2000 2003 2006 2009 20 12

Density log 10 no. per m

2

Year

3

2.5

2

1.5

1

0.5

Figure 17: Antarctic
krill postlarval
abundance (number
per m^2 ) within 10oE to
90 oW (Atkinson et al.,
2014).

The associated decline in winter sea ice extent is thought to be a

factor in krill decline. Over coming years, ocean acidification and

warming waters will have an impact on these species (Kawaguchi et

al., 2013; Hill et al., 2013). There is concern about the impact that

declines in krill will have on the food web of the Southern Ocean.

Krill is targeted by industrial fishing boats, and processed

into feed for aquaculture and livestock or omega-3 food

supplements. The total reported krill catch in 2013/14 was around

294,000 tonnes, the highest reported catch since 1991. Interest in

krill fishing continues to rise.

CCAMLR regulates the fishery within an interim trigger level

of 620,000 tonnes, around 1 per cent of the krill biomass in the

fished area.