World Aquaculture - December 2014

20 / 76

18 DECEMBER 2014 • WORLD AQUACULTURE •
Global rainbow trout
Oncorhynchus mykiss aquaculture
production reached 732,432 t in
2009, with a value of more than
US$ 3.4 billion (FAO 2011b). The
most important nations producing
rainbow trout in 2008 were Chile
(149,411 t), followed by Norway
(75,316 t) and Iran (62,630 t).
Rainbow trout was introduced into
Lebanon in 1958 (FAO 2011a).
Aquaculture in Lebanon
started as subsistence food
production in the 1930s (FAO
2011a). Commercial-scale
aquaculture in Lebanon started
in the 1990s, after the civil war.
Development, technical expertise
and a greater demand for seafood
products were provided by
investors and tourists who returned
after armed conflicts ended
(Lebbos and Saoud 2006).
More than 90 percent of
aquaculture production in Lebanon
is rainbow trout. The remaining 10
percent includes small quantities
of carp, catfish, penaeid shrimp
and tilapia. Rainbow trout
production in the country in 2002
was estimated by the Ministry of
Agriculture to be 600 t or by trout
farmers to be 1,000 t (Lebbos
and Saoud 2006). A 2011 article
published in the Lebanese daily
newspaper, Al-Akhbar (Al-Akhbar.
com), suggested that rainbow trout
production may have reached
1,700 t yearly. There are reportedly
150 fish farms in Lebanon, most
of them small, family-owned
businesses (FAO 2011a).
Most (70 percent) aquaculture
in Lebanon takes place along the
Assi (Orontes) River (Lebbos and Saoud 2006), near the northern
border with Syria, in earthen and concrete raceways (Figs. 1 and 2).
The Assi River is a perennial stream located in northern Lebanon,
Environmental Impact
of Trout Aquaculture on the
Lebanon Portion of the Assi River
Nadim Farajalla, Yara Daou, I.P. Saoud
a few kilometers northeast of
the Litani River source (Fig.
3). The Orontes River Valley
region is arid, mainly because
the mountain range on the
west side of the Bekaa Valley
deprives the valley of rainfall.
Annual precipitation averages
250 mm (El Moussaoui and
Yazigi 2005) and temperatures
vary between an average of
5.5 C in January to 32 C in
August (El Moussaoui 2001).
The Lebanese portion of the
Assi River, which flows north
into Syria, is 46 km long.
The annual flow rate of the
Lebanese part of the Assi River
is 480 million m3 (Ministry of
Environment 2001).
The Assi River has
excellent water quality for trout
aquaculture. It has the clear,
cool, oxygenated, fast-flowing
waters necessary to meet the
water quality requirements
of rainbow trout (Table 1).
However, these water quality
attributes also make the river
desirable for municipal uses,
traditional irrigation and
recreational activities. It is
imperative that aquaculture
not pollute the water, making it
unsuitable for other uses.
Fish farmers along the
Assi River near the town
of Hermel use earthen or
concrete raceways supplied
with constantly-flowing
water diverted from the river.
This has environmental
consequences that depend
on farm size, number of
surrounding farms, load of fish in each farm, intensity of feeding,
flushing capacity of the aquatic environment, bacteriology and
biodiversity of the milieu and land use around aquaculture farms
TOP, FIGURE 1.A rainbow trout farm along the Lebanon portion of the Assi
River. MIDDLE, FIGURE 2. Aerial view of trout ponds on the Assi River near
the town of Hermel, Lebanon. BOTTOM, FIGURE 3. The Assi (Orontes)
River and its watershed in northern Lebanon.