Climate Exchange

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griculture

Therefore, the hook rate of bigeye tuna and production rate of

Sardinella lemuru (Sardine) increased significantly in the EIO.

Climate impact on fisheries

The impacts of climate change on marine fisheries in Indonesian

waters are not well understood. Modelling and analysis of the poten-

tial impact of climate change on global fisheries has shown that the

potential fish catch in Indonesian waters will decrease by 15-30 per

cent due to global warming.

Based on data published by the Indian Ocean Tuna Commission

(IOTC), the three major bigeye tuna producers – Indonesia, Taiwan,

and Japan – saw a significant decrease in bigeye tuna production in

the EIO region from 1997 to 2010. Satellite data from theis period

also shows a downward trend in the abundance of phytoplankton,

and this decrease is thought to be one of the factors causing the

decline of the region’s bigeye tuna potential.

Fisheries production data for the past 15 years in two different fish

landing sites (the west Sumatra waters representing a non-upwelling

region and the Bali Strait representing an upwelling region) showed

a different trend. The dominant fish species caught in west Sumatra

waters were yellowfin tuna (Thunnus albacares), bigeye tuna and

Skipjack (Katsuwanus pelamis). Fisheries production in the west

Sumatra waters for 1994-2008 showed a decreasing trend concomi-

tant with a decreasing trend of chl-a concentration. Some researchers

explained that the declining trend of phytoplankton abundance in

tropical waters was related to the declining trend of nutrient supply

from the deep to the surface due to the global warming.

In contrast to the west Sumatra waters, Sardine production in

upwelling region of the Bali Strait was likely to increase over the

past 15 years. Modelling results on the impact of climate change on

global fisheries also showed that in areas of upwelling regions such

as the south coast of Java including the Bali Strait, the potential

fisheries productivity was also expected to increase.

Satellite data

also showed an increasing trend in phytoplankton abundance in

the Bali Strait. Global warming may have intensified the alongshore

wind stress on the ocean surface, leading to accelerations of coastal

upwelling in this region.

Sardine is a plankton feeder, and 52 per cent of the Sardine fish

density was affected by phytoplankton abundance in the Bali Strait.

The sardine spawning season in the Bali occurs around May-July

(the upwelling season). During the larval stage, sardines consume

plankton, and synchrony between the peak in plankton abundance

and the sardines’ larval stage is a crucial factor in determining the

survival of larva.

Managing production

Physical and biological oceanographic parameters influence the

distribution and abundance of fish in Indonesian waters. For

example, the highest sardine production correlated significantly

with the abundance of phytoplankton with the fourth month of the

time lag.

In Indonesia, the sardine plays an important role in the economics

of fishermen around the territorial waters of the Bali Strait, repre-

senting 90 per cent of fishery product in the area. Generally, sardine

production in the Bali Strait increases from October until January,

gradually decreasing in February. But in 1997-8 and in 2006-7

the sardine catch increased from October to July. This was due to

phytoplankton blooming in those years, and this positive anomaly

of phytoplankton was related to intense upwelling during IODM.

Otherwise, the fish production has declined sharply

when the concentration of phytoplankton is lowest.

Thus, the abundance of phytoplankton sustained the

stock of sardines in the Bali Strait.

Sardine production increased by 200-300 per cent in

1997-8 and 2006-7, and this actually produced a nega-

tive impact on the fishermen due to a sharp drop in

fish prices. The increase/decrease in fish production due

to climate variability and changes should be managed

by providing information on oceanographic condi-

tions that affect the abundance of fish. For example, an

increase in the abundance of sardines in the Bali Strait

can be predicted from the trend in chl-a concentra-

tions four months earlier. If the anomaly is positive,

the next four months is expected to see an abundance of

sardines. Therefore, appropriate management is needed

such as adjusting the number of vessels to catch fish so

that fish production will not be excessive, keeping some

excess production for further fish processing, or distrib-

uting the excess fish to other areas. In contrast, during

a negative anomaly of chl-a concentration, fish produc-

tion can be expected to decline so that it is necessary to

arrange a supply from other regions.

Another interesting example is the change in the

abundance of tuna in the Indian Ocean during the

blooming of phytoplankton due to climate variabil-

ity during IODM. Information about oceanographic

parameter variability can be used as an indicator to

predict the abundance of fish in the sea, to assist fisher-

men in fisheries management and ensure the availability

and security of fish.

In Indonesia, system information to predict potential

fishing grounds has been developed by the Ministry of

Maritime Affairs and Fisheries. This information is a

service to the fishermen, to improve the efficiency and

effectiveness of fishing efforts. The resulting map is

made using data analysis of oceanography parameters

from satellite imagery and multi-sensor climatologi-

cal data from the Indonesian Agency of Meteorology

and Climatology. This information system needs to be

improved, specifically in terms of its accuracy in forecast-

ing the long-term potential of fish resources, in particular

to anticipate the effects of climate variability and change.

Climate variations and changes seem to affect the fish-

eries productivity, and this is likely to bring a range of

opportunities and challenges to the fisheries sector in

Indonesia. In general, global warming causes a decline

in fish production in Indonesia. However, in upwelling

regions, global warming seems to increase fish produc-

tion due to an intensified upwelling process.

Variations in oceanographic conditions due to climate

significantly affect the potential of fishery resources in

Indonesia. Therefore the time series data and information

of oceanographic parameters such as sea surface temper-

ature, phytoplankton abundance and wind can be used

as a basis for better management of the risks associated

with climate variability and change as well for adaptation

so that Indonesia’s fisheries sector can be well managed

in terms of availability and food security.