Page 31 - World Aquaculture Magazine - March 2011

World Aquaculture 29
Fig. 3. Location of main aquaculture zones in Portugal.
Table 1. Table with prevailing Portuguese regions
and correspondent production, % of used
surface and % of farms. (Source: INE,
2010)
Region Production Used Farms
(tons and %) surface % %
North 976 (12%) 0.1% 0.1%
Centre 1305 (16%) 22% 6%
Lisbon Region 599 (8%) 25% 4%
Alentejo 321 (4%) 6% 1%
Algarve 4331 (54%) 46% 89%
Madeira 455 (6%) 1% 0.2%
ductivity was only near 8% (table 1), partially explained
by the low intensification of rearing systems. Aquaculture
practices are mainly dedicated to seabream production in
earth ponds, together with some volume of seabass. The
Lagoa de Albufeira is an ample lagoon where clams and
mussels are produced.
The Alentejo coast has a small area of 105 ha for aqua-
culture exploitation, producing mainly seabass, seabream,
clams and oysters. It is very interesting to notice the exist-
ence, in this site, of natural banks of the Portuguese oys-
ter ( Crassostrea angulata) which is an isolated occurrence
in national aquaculture. This is the only place in Portugal
where the wild species flourishes in the natural environ-
ment. Fish is reared using extensive, semi-intensive and in-
tensive systems, with seabass as the main species produced
and representing 70% of total fish farming in Alentejo.
Algarve is the most important region for Portuguese
aquaculture with the highest yearly production contrib-
uting with 4331 tons in 2008, which corresponds to 54%
(table 1) of national aquaculture (INE, 2010). This region
comprehends two distinctive zones: a smaller area – the Al-
vor estuary and the Ria Formosa lagunar system. Ria For-
mosa is the largest area devoted to aquaculture in Portugal
and the most important wetland area in Portugal, compris-
ing 750 ha of surface. This wide area is formed by a large
system of canals and lagoons.
Almost 90% of the total number of Portuguese farms
is located in Algarve. The vast majority (96%) are conces-
sions for extensive rearing of molluscs (Source: DGPA).
Around 73% of the total volume of clams and oysters are
produced in this region. The favourable ecological condi-
tions allow a fast growth and favour the management and
access to the molluscs’ production areas.
Conditions in South region and Algarve are particularly
adequate to the growth of seabream which is the main spe-
cies produced commonly as a polyculture together with
seabass, and sometimes with sole. Fish species are cultivat-
ed in semi-intensive systems, usually in earth ponds re-built
from abandoned salt ponds.
Aquaculture in Madeira is exclusively for intensive pro-
duction of seabream. Started in 2002 as a regional pilot
project and has been regularly growing in the past years,
with two units presently operating under private manage-
ment. Inland production of trout exists in Madeira, but
in a very small scale, and is used solely for restocking pur-
poses.
In Azores, there is an ongoing discussion on systems
and species to be exploited by aquaculture (Pham et al,
2008), and did not have any impact on Portuguese aqua-
culture so far.
Production Systems
The most common aquaculture systems are the ones used
for extensive rearing of molluscs in intertidal areas, which,
together with some long lines units, represent 50% of the na-
tional production. Either semi-intensive or intensive systems
correspond to 25% of total production and are mainly used
for fish cultivation. Marine fish are maily produced in earth
Fig. 4. Molluscs havesting at Ria de Alvor (Algarve) (Photo: A.
Ramalho)