Living Blue Planet Report

Chapter 1: The state of our blue planet page 19

Figure 14: Population
trends in two
commercial fish species
from the Southern
Ocean – marbled rock
cod and mackerel
ice fish – show sharp
declines in the 1970s
(CCAMLR, 2013b; Duhamel
et al., 2011).

0

300

250

200

150

100

50

1977 1978 1979 1980 1981 1982 1983 1984 1985 1986

Spawning stock biomass

(X 1,000 tonnes)

Year

0

1975 1976 1984 1986

Spawning stock biomass

(X 1,000 tonnes)

Year

16

14

12

10

8

6

4

2

Key

Marbled rock cod

(South Orkney

Isla nd s)

Mackerel icefish

(South Orkney

Isla nd s)

Polar habitats: Southern Ocean

Despite its remoteness, the rich marine life of the Southern Ocean

has experienced some of the sharpest recorded declines in fish

populations (WWF, 2014). Limited data means it is not possible to

develop a reliable overall index for the Southern Ocean. However,

a massive decrease in population numbers of some commercially

targeted fish species can be observed in the late 1970s, following

increased fisheries activity in the region (Figure 14) (CCAMLR,

2013b). Illegal, unregulated or unreported (IUU) fishing is a

particular concern in the Southern Ocean (Osterblom and Bodin,

2012; CCAMLR, 2013a).

Unsustainable levels of fishing have been largely curtailed

since the establishment of the international Commission for the

Conservation of Antarctic Marine Living Resources (CCAMLR)

in 1982 (Figure 16). The Ross Sea toothfish, for example, is now

managed to a target of 50 per cent of the original stock biomass

(Figure 15). This is a conservative limit that enables productive

commercial exploitation while minimzing the risk of stocks

becoming depleted. CCAMLR has adopted an ecosystem-based

management system, and has also substantially reduced levels of

IUU fishing and seabird bycatch.