International Journal of Marine Science 2015, Vol.5, No.23 1-13
3
study. Catch per unit effort (CPUE) is defined as one
operation of the net which occurred once per site or
the number of fish collected per operation. CPUE was
expressed as No. 100 m-net hr-1 and used as index of
relative abundance (FAO, 2002; Sparre and Venema,
1992). Total catch was collected and sorted into finfish
and shell fish. After sorting and counting,
representative finfish samples were preserved in 10%
formalin for taxonomic studies. Species level
identification was made
with help of standard
references (Talwar and Jhingran, 1991; Bijoy Nandan,
2012; Fish Base (
.
Figure 1 Location of the sampling sites in the Vembanad estuary (Source: IRS.IA LISSLANSAT IMAGE 1990)
Water temperature was measured at the time of
sampling using mercury thermometer; pH with
Systronics pH meter (No. 317; accuracy ± 0.01);
transparency using Secchi Disc (Strickland and
Parsons, 1972); dissolved oxygen by modified
Winklers method (Strickland and Parsons, 1972) and
salinity by Systronics water analyser (No. 317;
accuracy ±0.01) calibrated with standard seawater.
1.3 Data Analysis
Two-way analysis of variance (ANOVA) was used for
hydrological parameters (temperature, pH, transparency,
dissolve oxygen and salinity) to calculate any
existence of difference among the stations, months
and seasons. Species diversity, richness and evenness
index of fin fishes were calculated for each gill net
sample based on species numerical abundance.
