World Aquaculture - December 2014

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• WORLD AQUACULTURE • DECEMBER 2014 19
(Boaventura et al. 1997). Fish on
the downstream part of the river
live in effluent from farms located
upstream.
Water quality is not the only
factor affecting rainbow trout health.
Crowding, improper handling,
grading, pond cleaning and other
routine activities are additional
factors that stress fish and can
lead to increased susceptibility to
pathogens (Pickering 1992). In many
countries, fish farmers are assisted
in the management of water quality
and environmental parameters by
government and academic institutes
and extension agents, but this is not
the case for the trout farmers of
Lebanon.
Aquaculture has generated
massive enthusiasm in the past two
decades, with some viewing its
development as a ‘blue revolution’
with tremendous potential for
food security, economic growth in
rural areas and poverty alleviation.
However, growth in fish farming,
as with all farming activities, has
environmental impacts, which must
be managed if production is to be sustainable.
Other than the flow rate of the Assi River, very little is
known about water quality and no studies of the impact of trout
aquaculture on the Lebanon portion of the stream are available.
Here we describe a study performed on the river to assess levels
of pollution, effects of aquaculture on river water quality and local
stakeholder perceptions of aquaculture and the environment.
Study Survey
A survey of trout farmers along the length of the Assi River in
Lebanon was done in 2012. Farms were identified and a list of 49
farmers who fully or partially own ponds along the Assi River was
established. Geographic coordinates of each farm were estimated
using Google Earth imagery. Survey results cover 199 ponds from
the source of the Assi River to the last accessible point before the
Lebanon-Syria border. Every trout farm owner or manager along
the river was interviewed and informal conversations with the
mayor of Hermel, recreational activity (e.g. rafting and camping)
organizers and restaurant owners bordering the river, were
recorded.
A detailed questionnaire was prepared in English and
translated to Arabic. It included questions related to land and
ponds, fish production, feeding and environmental practices and
the farmers’ personal opinion about the state of aquaculture in the
river valley. Questions were posed at random and in no specific
order. The veracity of some answers was controlled by asking some
farmers if the information given by other farmers was correct.
Raceway Design and
Construction
The design and construction
of ponds and raceways on fish farms
of the Assi River valley is diverse.
Only earthen raceways (Fig. 4) are
used by 43 percent of farmers, both
earthen and concrete raceways
are used by 34 percent and only
concrete raceways (Fig. 5) are used
by 23 percent. In general, those with
concrete raceways thought they
were better and those with earthen
raceways defended their use.
There are two main reasons to
explain the prevalence of earthen
raceways along the Assi River.
First, earthen raceways are less
expensive to build than concrete
raceways. Trout farmers who
believe that concrete raceways
are better often lack the funds to
transform their earthen raceways
to concrete. Some trout farmers
who rent raceways perceive the
expense of transforming earthen
raceways to concrete raceways as
unnecessary, inasmuch as they
will not benefit from the investment
over time because they do not own them.
The other reason to explain the prevalence of earthen raceways
is that many farmers assert that trout reared in earthen raceways are
healthier, more colorful and a better-quality product. Thirty-eight
percent of farmers believe that earthen raceways are better for trout
health and welfare than concrete raceways. Some of the reasons given
were that fish feed on small plants growing in the soil and hence
obtain more nutrients and grow faster. Also, some believe the soil acts
as a filter, cleaning the water in which trout are grown.
A majority (53 percent) of trout farmers thought yields from
earthen raceways were better than from concrete raceways. Another 13
percent believe that rearing rainbow trout in earthen or concrete race-
ways gives similar results and therefore deem the additional expense
of building a concrete raceway unnecessary. Piper et al. (1982) also
reported that some trout farmers stand by their opinion with respect to
high yields from earthen raceways. Survival of rainbow trout does not
seem to depend on the type of the raceway, earthen or concrete.
Thirty four percent believed that concrete tanks were better
because, in contrast to earthen tanks, they can be totally cleaned of
waste. Furthermore, no aquatic animal can dig into them and allow
fish to escape. They are difficult for pests or predators (e.g. snakes,
rats or frogs) to enter and prey upon trout fingerlings. Eleven percent
of farmers stated that they were certain that concrete raceways helped
reduce fingerling mortality and offered better population control. Fish
and water quality in concrete raceways are much easier to manage
than in earthen raceways (Piper et al. 1982, Hinshaw 2000, Dunning
and Sloan 2001).
( C O N T I N U E D O N P A G E 2 0 )
TOP, FIGURE 4. Earthen raceways along the Assi River, Lebanon.
BOTTOM, FIGURE 5.Concrete raceways along the Assi River, Lebanon.