A Climate for Change

Human Development Report - Croatia 2008 The Fishing and Mariculture Industries^157

The scenario for sea bass is similar for the flat oyster.
The dangerous/ lethal temperature for the flat oyster
is 26°C, which has already been measured along the
coastline and in the traditional culture grounds in Mali
Ston Bay.^22 Incidents of summer mortality of the flat
oyster in some areas of Mali Ston BayXVI have already
been reported.^23 As the Integrated Developmental
Strategy of Mali Ston Bay calls for a significant increase
in the production of this lucrative species, water tem-
perature increases will be a major obstacle for long-
term planning. As with the sea bass, as sea tempera-
tures rise, oyster production should be transferred to
deeper water during critical summer months, which
will result in associated new costs. For most farms,
this should mean the simple addition of a few metres
of rope, but for other farms this change will involve
changing the production site completely. While this is
not a complicated adaptation measure, it will increase
the costs of flat oyster production. However, the flat
oyster should similarly benefit from a prolonged grow-

ing season, an earlier and longer reproduction season,

and a reduction in the length of the rearing cycle.

In general, the effects of global warming on the shell-

fish culture should be positive, but some changes in

culture practice will probably be necessary.

9.5.3. Future impacts: Invasion of new

species

As fish respond to warming waters – as evidenced

by the northerly advance of southern species in a

systematic way – they may provide a useful index of

the effects of warming in the Adriatic. The incoming

north-westward current along the eastern Adriatic

coast carries food and plankton organisms and pro-

Type of fish Mariculture or Fishing? Economic Importance Likely Impact of Climate Change Potential Adaptation Mechanism? (if needed)

Tuna Mariculture High – especially for

export

Positive due to increased tem-

peratures

None needed

Flat Oyster Mariculture High – around Mali

Ston Bay

Negative – especially if tem-

perature is over 26.5 C

Transfer to deeper water in

production if temperatures

rise.

Sea Bass Mariculture Medium Negative due to increased

temperatures

Culture in deeper cages or

colder sites

Sea Bream Mariculture/

Fishing

Medium Positive- faster growth, pro-

longed spawning season

None needed

Sardine Fishing High- for tuna farming

and canning industry

Moving of spawning centres,

expanding of spawning period,

negative according to effects of

predators

None

Anchovy Fishing High- for salting

industry

Moving of spawning centres,

prolonged spawning season,

negative according to effects of

predators

None

Hake Fishing High for canning

industry and fish

markets

Moving of spawning centres,

prolonged spawning season

None

Norwegian

lobster

Fishing High for markets Effects on boreal species, chang-

es in bathymetric distribution

None

Table 9-3: Important commercial fish in Croatia and the likely impact of climate change

XIV This is part of the COAST project being coordinated by UNDP

Croatia.

In general, the

effects of global

warming on

the shellfish

culture should

be positive, but

some changes in

culture practice

will probably be

necessary