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<br />W. T. BARHAM, H.l. SCHOONBEB&I. 0.1. VISSER
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<br />TABLE 3 The effect! of duratIon of \:Drrent flow on opercular recovery time, narcosIs time and recovery time In O. mos~ambiCUI subjected to
<br />rectified current electronarcosis at 200 Vp
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<br /> Opercular Narcosis Recovery Narcosis
<br /> Length (cm) Mass (g) recove~ coefficient
<br /> time (s time (s) time (s) (s cm-I)
<br /> n= 8 8 8 8 8 8
<br /> Minimum 21,6 187,9 24,9 " ,.,44,4 11,8 1,8
<br />.. Maximum 27,4 312,6 35,8 ' ,f'J 101,1 87,6 4,5
<br />:l Range 5,8 124,7 10,9 56,7 75,8 2,7
<br />Mean 24,4 241,6 31,3 65,4 35,3 2,7
<br /> Standanl Dev. 2,3 51,6 3,9 21,6 25,3 1,1
<br /> Standanl Err. 0,8 18,2 1,4 7,6 8,9 0,4
<br /> n= 8 8 8 8 8 8
<br /> Minimum , 22,4 207,9 37,0 97,3 4,2 3,9
<br /> Maximum ' 28,4 \ 366,7 97,0 182,7 127,8 8,2
<br />.. Range 6,0 158,8 60,0 85,4 123,6 4,3
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<br />.., Mean 25,5 275,0 59,6 137,4 58,1 5,5
<br /> Standanl Dev. 2,1 60,2 21,5 33,7 44,7 1,6
<br /> Standanl Err. 0,8 21,3 7,6 11,9 15,8 0,6
<br /> n= 8 8 8 8 8 8
<br /> Minimum 22,8 187,6 42,9 115,2 22,2 5,0
<br />.. Maximum 25,8 " 277,2 70,6 224,4 177,5 9,5
<br />II'> Range 3,0 89,6 27,7 109,2 155,3 4,5
<br />'<t' Mean 23,7 225,3 57,8 161,6 76,1 6,8
<br /> Standard Dev. 0,9 25,2 ,12,1 37,2 53,9 1,5
<br /> Standard Err. 0,3 8,9 4,3 13,1 19,0 0,5
<br /> n= 8 8 8 8 8 8
<br /> Minimum 21,4 159,8 45.6 77,6 35,6 3,4
<br /> Maximum .28,1 317,1 .69,3 157,1 146,6 5,8
<br />.. Range 6,7 157,3 . 23,7 79,5 111,0 2,4
<br />~ Mean 24,7 241,8 58,1 112,6 89,8 4,6
<br /> Standard Dev. 2,5 63,5 9,0 26,7 38,7 1,1
<br /> Standanl Err. P,9 22,4 3,2 9,4 13,7 0,4
<br /> n= 8 8 8 8 8 8
<br /> Minimum 20,8 159,2 53,3 121,6 47,3 5,9
<br />.. Maximum 27,0 323,4 140,1 274,6 1%,2 10,6
<br />II'> Range 6,2 164,2 86,8 153,0 148.9 4,7
<br />r-- -
<br /> Mean 23,9 236,7 98,9 193,1 94,1 8,0
<br /> Standanl Dev. 2,2 57,1 33,4 50,4 52,7 1,7
<br /> Standanl Err. 0,8 20,2 11,8 17,8 18,6 0,6
<br /> n= 8 8 ' ' 8 8 8 8
<br /> Minimum 24,0 192,7 76,3 181,1 36,1 6,6
<br />.. Maximum 27,3 321,7 114,0 284,5 165,4 11,8
<br />~ Range 3,3 129,0 37,7 103,4 129,3 5,2
<br /> Mean 25,1 248,3 98,4 223,3 119,5 8,9
<br /> Standanl Dev. 1,1 39,0 13,7 32,9 43,5 1,6
<br /> Standard Err. 0,4 13,8 ' 4,8 11,6 15,4 0,6
<br /> 15130 (df = 14) NS NS 3,663 (P=O,OI) 5,087 (P=O,OOI) NS 4,079 (P=O,OOI)
<br /> 15/45 (df = 14) NS NS 5,8% (P=O,OOI) 6,325 (P=O,OOI) 1,938 (P=O, 1) 6,234 (P=O,OOl)
<br /> 15/60 (df = 14) NS NS 7,728 (P=O,OOI) 3,887 (P=O,OI) 3,334 (P=O,OI) 3,454 (P=O,Ol)
<br /> l5n5 (de = 14) NS NS 5,686 (P=O,OOI) 6,587 (P=O,OOI) 2,845 (P=0,02) 7,403 (P=O,OOI)
<br /> 15190 (de = 14) NS NS 13,324 (P=O,OOI 11,348 (P=O,OOI) 4,732 (P=O,OOI) 9,032 (P=O,OOI)
<br /> 30/45 (df = 14) 2,228 (P=O,05) 2,154 (P=o,o5) NS NS NS NS
<br /> 30/60 (df = 14) NS NS NS NS NS NS
<br /> 30n5 (df = 14) , NS NS 2,798 (P=O,02) 2,598 (P=O,05) NS 3,029 (P=O,OI)
<br /> 30190 (df = 14) NS NS 4,305 (P=O,OOI) 5,159 (P=O,OOI) 2,784 (P=O,02) 4,250 (P=O,OOI)
<br /> 45/60 (df = 14) NS NS NS 3,027 (P=O,Ol) NS 3,345 (P=O,OI)
<br /> 45n5 (df = 14) NS NS 3,272 (P=O,OI) NS NS NS
<br /> 45190 (df = 14) 2,786 (P=O,02) NS 6,282 (P=O,OOI) 3,514 (P=O,OI) 1,772 (P=O,I) 2,708 (P=O,02)
<br /> 6On5(df= 14) NS NS 3,336 (P=O,OI) 3,992 (P=O,OI) NS 4,749 (P=O,OOl)
<br /> 60190 (df = 14) NS NS 6,954 (P=O,OOI) 7,390 (P=O,OOI) NS 6,264 (P=O,OOI)
<br /> 75190 (df = 14) NS NS NS NS NS NS
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<br />df = degree of freedom; P = two-tailed probability; NS = not significant
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<br />Effects of temperatute
<br />
<br />The physical effects of electronarcosis at different
<br />water temperatures on the fish are presented in Table 2
<br />and illustrated in Fig. 2. Although there were significant
<br />differences in mean length and mean mass between the
<br />fish used in the 15 oC experiment and those used at 25 oC,
<br />these differences were only 1,7 cm and 77 ,1 g, respect-
<br />ively and at the calculated narcosis coefficient values for
<br />the fish at the two temperatures the length difference
<br />represents a maximum effect on narcosis time of 15.3 s
<br />and a minimum effect of 8.3 s. It is clear that these
<br />differences could not have had appreciable e.ffects on the
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<br />results obtained. Mean opercular recovery time at 15 oC
<br />was somewhat longer than at higher temperatures but
<br />there was no significant differences between mean oper-
<br />cular time at 20 oC and that at 25 oC. The fish at 15 oC
<br />remained narcotized for periods highly significantly
<br />longer (P = 0,001) than did fish at the two higher
<br />temperatures. At the higher temperatures there was no
<br />significant difference in narcosis times.
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<br />There was a highly significant difference (P = 0,001)
<br />between the mean narcosis coefficients of fish kept at 15
<br />oC and those held at 25 oC. The mean narcosis coefficient
<br />at 15 oC was also significantly greater (P = 0,01) than
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