Untitled - WWF - Pakistan

Detailed Ecological Assessment Report 2008 – Keenjhar Lake
2.5.2 Cast-netting technique
A general survey of the reservoir area was conducted to identify different habitats
in the study area. Field stations were selected covering all the representative
habitats of the study area. Long/Lat of all the field stations was noted to make it
more accessible during the study period. Fish will be collected using cast nets of
two different mesh sizes, (small one having mesh size of 1cm X 1cm and having
a circumference of 30 ft. and the large one with mesh size of 2.5cm X 2.5cm and
with a circumference of 45ft.) so that the fish fauna of all the age classes could be
collected. Ten nets of each mesh size were cast in each stations along a line
transect of about 500 meters. The collected material was numbered according to
stations and the effort no. and mesh size. The fish specimens were preserved in
10% formaldehyde solution in the field. Large specimens were given an incision
in the belly to ensure proper preservation. The specimens were identified in the
laboratory and taxonomical checklists along with English and local names were
compiled.
The status of each species (common, rare, fishery value, maximum size etc. )
was determined on the basis of relative abundance of each species in the project
area. The data on fish species collected in each station and of every habitat along
with their long./lat. was available for developing GIS based information regarding
occurrence and distribution of fish species in the lake. Any possible change in the
last ten or so years in fish population fish was anticipated on the bases of data
collected, previous studies carried out in the area and on the basis of interviews
of the fishermen and local people, agro-forestry practices and irrigational pattern
in the area and conservational measures that could be expected in future. The
fishes of special concern i.e., fishes of economic value and fishes of ecological
concern were given special attention and were documented and enlisted on the
basis of the first hand information collected by the actual data and the information
already available through previous studies.
2.6 Phytoplankton
2.6.1 Collection methodology
Algal and phytoplankton species were collected in June and November 2007. A
small boat was used along with a phytoplankton net of 5-10 µm mesh to collect
samples. Water samples were collected each time using a water sampler
(Nansen bottle) commonly unused for studying physico-chemical features, using
standard methods (APHA, 1985) and for identification of phytoplankton. Samples
were preserved in 4% formalin solution (Mason, 1967). The species composition
was determined by utremohal method (Lund, 1958). The micro algae (ultra
nanoplankton) were not counted as Gorham et al (1974) considered these algae
comparatively un-important in high productive water-bodies. Identification and
counts were done using inverted light microscope (BH-2 Olympus using
objectives 10 X , 20 X , 40 X , 100 X but usually 20 X and 10 X eye piece was used) and
identified with the help of available literature (Tilden, 1910; Husted, 1930; Majeed,
1935; Smith, 1950; Silva, 1954; Desikachary, 1959; Prescott, 1962; Siddiqi &
Farooqi, 1964; Patrick, 1966; Philpose, 1967; Islam & Tahmida, 1970; Tiffany &
Briton, 1970; Vinyard, 1979; Akiyama & Yamagishi, 1981; Shameel, 2001).
2.7 Zooplankton
2.7.1Collection protocols and standardizing procedures
Specimens belonging to diverse groups of Invertebrates were collected from the
various localities of the prescribed areas using a variety of collection protocols and
techniques.
WWF Pakistan – Indus for All Programme Page 31 of 165