| Naga
- The *ICLARM Quarterly
Vol.
22, No. 4 (October - December 1999)
Network
of Tropical Aquaculture Fisheries Professionals
(NTAFP) Section
Aquabyte
(Aquaculture Section of NTAFP)
Brush
Shelter: A Recently Introduced Fishing Method
in the Kaptai Reservoir Fisheries in Bangladesh
K.K.
Ahmed and J.B. Hambrey
Abstract
Since
the early 1990s, the brush shelter fish aggregation
device (FAD), an unusual fishing method used in
Bangladesh, has become popular with the fishers
of Kaptai Lake. A shelter commonly covers an area
between 0.02 and 0.12 ha and is usually installed
along the edge of a channel (arm of lake) with
a reasonable water depth. Brushes are square/rectangular/round
surrounded with bamboo or wooden frames constructed
with tree branches. To attract fish, water hyacinth
is placed over the surface. The difference between
this fishing practice and similar ones used elsewhere
in Bangladesh is that it makes use of locally
available feed ingredients (rice bran, wheat bran,
mustard oil cake, fermented rice, etc.). Spices
and fish scents are also used two to three days
prior to harvest. It is estimated that about 1000
brush shelters are in operation around the reservoir
and are fished twice a year. The quantity of fish
caught in each brush varies directly with the
size and location of the brush and feed quality.
A total of 483 t of fish of different species
is harvested annually, accounting for about 8%
of the total catch from the reservoir. Unplanned
and unregulated use of this type of fishing poses
a serious threat both to the natural stocks and
to the effectiveness of stock enhancement as mostly
small fish are harvested.
K.K.
Ahmed is from the Bangladesh Fisheries Research
Institute Riverine Sub-station, PO Box-8, Rangamati-4500,
Bangladesh. J.B. Hambrey is from the Aquaculture
and Aquatic Resources Management Program, School
of Environment, Resources and Development, Asian
Institute of Technology, Bangkok, Thailand.
Broodstock
Management Status and Some Suggestions to Control
Negative Selection and Inbreeding in Hatchery
Stocks in Bangladesh
M.G.
Hussain and M.A. Mazid
Abstract
The
freshwater river systems and floodplains of Bangladesh
are the breeding grounds for 13 endemic species
of carps and barbs and a large number of other
fish species, including a number of exotic carps
and other species that have been introduced for
aquaculture. Since 1967, breeding of endemic and
exotic aquaculture species for seed production
through hypophysation techniques has become a
common practice. Over 700 hatcheries established
in the private and public sectors have been breeding
13 endemic and 13 exotic fish species and contributing
more than 98% (about 117 000 kg) of the total
spawn (hatchery) production. Stock deterioration
in hatchery populations due to poor broodstock
management and inbreeding depression has been
observed. Retarded growth, poor reproductive performance,
morphological deformities, increased incidence
of disease and mortality of hatchery-produced
seeds have been reported. The widespread stocking
of such genetically poor quality fish seed in
closed and open waterbodies is causing concern.
In this situation, there is an obvious need to
adopt proper broodstock management strategies
and breeding plans for commercially important
fish species.
The
paper describes the present status of broodstock
management, identifies problems, and suggests
some guidelines to control negative selection
and inbreeding in hatchery stocks in Bangladesh.
M.G.
Hussain and M.A. Mazid are from the Bangladesh
Fisheries Research Institute, Mymensingh 2201,
Bangladesh.
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