High opening trawl was found to be effective for the exploitation of bottom and off bottom fishes from Hirakud reservoir compared to bulged belly trawl

Dawson, P.

George, V.C.

Khan, A.A.

Krishna Iyer, H.

Varghese, M.D.

Aquatic Commons

High ope- 
ning trawl 
Bulged belly 
trawl 
Total 	 Catch 
catch, kg h-- 1 , kg 
56 	 2705.09 	 48.35 
56 	 1911.50 	 34.13 
Type of net Duration 
of opera-
ration, h 
Effldlei cy of Two Designs f Trawls in Hirakud Reservoir 
V. C. GEORGE, PERCY DAWSON, A. A. KHAN, M. D. VARGHESE and 
H. KRISHNA IYER 
Central Institute of Fisheries Technology, Cochin - 682 029 
High opening trawl was found to be effective for the exploitation of bottom and off 
bottom fishes from Hirakud Reservoir compared to bulged belly trawl. 
Trawling in Indian reservoirs was dis-
cussed by Anon (1979) and George et al. 
1982. The present communication deals with 
the study of two types of trawls in Hirakud 
Reservoir. 
Materials and Methods 
Comparative fishing experiments with a 
13 m bulged belly (George et al. 1982) and 
12 m high opening trawl (Fig. 1) with 100x 
50 cm flat rectangular otter boards were 
undertaken in selected grounds of Hirakud 
Upper 	 Lower 
Fig. 1. 12 m high opening trawl 
reservoir. The method of operation and 
boat used were the same as described by 
George et al. (1982). Catch of fish at three 
different speeds of boat (2.4, 2, 1.6 knots), 
catch per unit effort, variation in the catch 
in the morning and evening and catch com-
position of the above two nets were noted 
based on 168 comparable hauls of 20 min 
duration made with each net. 
Results and Discussion 
The data collected on comparable hauls 
with respect to speed and catch rate of 
both the nets during morning and evening 
hours were analysed. In Table 1, the catch 
h° 1 of trawling of the bulged belly and 
high opening trawl is given. It is evident 
Table 1. Catch per unit effort of high ope-
ning and buldged belly trawls 
that the high opening trawl landed more 
catch as observed by Pillai et al. (1979). 
No significant difference in the catch of the 
two nets at different speeds at morning and 
evening was observed (Table 2). However 
significantly higher catch of R. cotio was-
obtained in the high opening net compared 
to bulged belly (p<0.05.) This increase in 
catch is due to the higher vertical opening 
of the high opening net which caught more 
Vol. 23, 1986 
44 	 V. C. GEORGE, PERCY DAWSON, A. A. KHAN, M. D. VARGHESE 
AND H. K. IYER 
Table 2. Anova table for catches 
R. cotio Source S.S. di ins F. 
Total 17.3961 97 
Time 0.6610 1 0.6600 3.85 
Nets 0.7336 1 0.7336 4.28* 
Speed 0.0748 2 0.0374 1 
Error 15.9277 93 0.1713 
M. seenghala Total 5.4582 71 
Time 0.2742 1 0.2741 3.79 
Nets 0.0031 1 0.0031 1 
Speed 0.3293 2 0.1647 2.27 
Error 4.8516 67 0.0724 
W. attu Total 6.8607 71 
Time 0.0813 1 0.0813 1 
Nets 0.0223 1 0.0223 1 
Speed 0.1467 2 0.0734 1 
Error 6.6104 67 0.0987 
Sciaenids Total 1.1631 47 
Time 0.0084 1 0.0084 
Nets 0.0009 1 0.0009 1 
Speed 0.0487 2 0.0244 1 
Error 1.1051 43 0.0257 
Miscellaneous fish Total 5.2798 83 
Time 0.0629 1 0.0629 1.005 
Nets 0.0462 1 0.0462 1 
Speed 0.0462 1 0.1124 1.796 
Error 4.9460 79 0.0626 
* Indicate significance at 5% level 
of bottom fish like R. cotio. This suggests 
that exploitation of bottom and off bottom 
fishes from reservoirs can be achieved with 
high opening trawls. 
The authors are grateful to the Director, Central 
Institute of Fisheries Technology, Cochin for the 
encouragement as well as for according permission, 
to publish this paper. They are also thankful to 
the crew for their services to execute this study. 
References 
Anon (1979) Fish. Tech. News Letter, 1, 8 
Anon (1979) Fish. News int. 18, 12 
Pillai, N.S., George, N.A. & Nair, A.K.K. 
(1979) Fish. Technol. 16, 65 
George, V.C., Percy Dawson, Khan, A.A. & 
Varghese, M.D. (1982) Fish. Technol. 
19, 15 
FISHERY TECHNOLOGY 


Efficiency of two designs of trawls in Hirakud Reservoir

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Efficiency of two designs of trawls in Hirakud Reservoir

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