, ( Acipenser sinensis)

Transcription

1 26 6 Vol. 26,No ACTA HYDROBIOLOGICA SINICA Nov., (, ) :, , 5km,,, 11, , : ; ; ; : S93214 :A : (2002) , ( Acipenser sinensis) 5km,, 4 5d( Coreius guichenoti) ( C. heterodon) ( Pelteobagrus vachelli) [1 ],90 % [2 ],,, [3,4 ] , 10 11, ( mm, g) ;, 5 246d 10, ; 25, ,246d,345 ( : ; : : [ SX(98)215/ KHB/ JS] :(1970 ),, ; ;, 99, :,E2mail ac. cn

2 ) 164d,1430 ( 1) 36 8, 1 Tab. 1 Sample sizes of drifted trammel net and longline in the spawning ground of Chinese sturgeon Surveying periods Drifted trammel net Longline Sampling Sampling Daily sampling days boats boats Number of Sampling Sampling Daily sampling captures days boats boats Number of captures Sum , (CPUE), CPUE 365d, CPUE 113, [5 ],,, CPUE,, CPUE, 114 Jones [5 ] : N i = ( N i + 1 e t M/ 2 + C i ) e t M/ 2 (1), N i N i + 1 i i + 1 ; C i i ; M, ; t L i L i + 1, :

3 6 : 593 t = (1/ k) ln[ (L - L i ) / ( L - L i + 1 ) ] (2) L K von Bertalaffy N i C i E i : N i n i : n i N i = C i / E i (3) = N i dn/ ( F i + M) = ( N i - N i +1 ) / ( F i + M) (4) N i+1 (4) F i, E i M : n i, n F i = M E i / (1 - E i ) (5) 115 L K [6,7 ] M L K Pauly [8,9 ], 18. 4, M L k M,, 10mm, (1) (3) C i E max 0. 5,(3), (1) (2) (4) (5), EXCEL , 25, 11, 3 ( 2) 2 Tab. 2 Species composition of egg2predatory fishes and their harmfulness to egg of Chinese sturgeon during spawning seasons Species Number of fish surveyed Number of egg2predatory fishes ( ) Eggs eaten by egg2predatory fishes Eggs eaten by per fish Coreius guichenoti Pelteobagrus vachelli Coreius heterodon Leiocassis longirostris L. crassilabris Rhinogobio ventralis

4 Species Number of fish surveyed Number of egg2predatory fishes ( ) Eggs eaten by egg2predatory fishes Eggs eaten by per fish R. cylindricus Leptobotia elongata Pelteobagrus nitidus Gobiobotia filifer Silurus meridionalis 2 1 Not be counted Sum or average CPUE , , % % % % %, ,,, ( C i ) ( 3) 3 Tab. 3 Length groups and yields of each group of C. heterodon in the spawning ground of Chinese sturgeon Length groups (mm)

5 6 : 595 Length groups (mm) Sum ,L mm k , Pauly, M , , : L = k = M = E max = 0. 5, (1) (5), ( 4) 214, , ( 4)

6 Tab. 4 Annual abundance of egg2predatory fishes in the spawning ground of Chinese sturgeon Species C. guichenoti C. heterodon R. ventralis R. cylindricus P. vachelli L. longirostris G. filifer P. nitidus L. elongata L. crassilabris S. eridionalis Sum , CPUE,, , ( 5)

7 6 : Tab. 5 CPUE and s of egg2predatory fishes estimated from samples of different periods Years CPUE CPUE estimated from samples in the spring of egg2predatory fishes in the spring CPUE CPUE estimated from samples before spawning of Chinese sturgeon of egg2predatory fishes before spwaning of Chinese sturgeon CPUE CPUE estimated from samples in spawning period of Chinese sturgeon of egg2predatory fishes in spawning period of Chinese sturgeon CPUE CPUE estimated from samples after spawning of Chinese sturgeon of egg2predatory fishes after spwaning of Chinese sturgeon ,, [4 ],,,,,,,,, 80 %, (CPUE),,, 312 CPUE,, ( M),Jonse,,,,

8 598 26,CPUE, Cushing,, [10 ],,,, CPUE,,,,CPUE,,,, 2 2,,,,,CPUE,,, 2 :, ; 313,,,,,, 1999, 370mm, ( mm) % mm,,, 0. 5,,, ,5. 27, [11 ], 4 (4 5d),,16 20, : [ 1 ],,,. [J ].,1999,23(6) : [ 2 ]. [D]. :

9 6 : 599,1999 [ 3 ] 1 [J ].,1997, (9) :6 17 [ 4 ],, 1 [J ].,1994,6(3) : [ 5 ] Per Sparre, Siebren C. Venema. [M]. :,1992 : [ 6 ],, 1 [J ].,1981, 7(3) : [ 7 ],1 [J ].,1999,23(6) : [ 8 ] 1 [J ].,1975,5(3) : [ 9 ] Pauly, D. On the interrelationship between natural mortality, growth parameters, and mean environmental temperature in 175 fish stocks [J ]. J. Cons. Int. Explor. Mer. 1980,39(20) : [10 ], 1 [M]. :,1990 [11 ],,,. [ C]. ( ), :,1986 :1 14 ESTIMATION ON ABUNDANCE OF BENTHONIC FISHES PREYING ON EGGS OF CHINESE STURGEON IN REACH BELOW THE GEZHOUBA DAM IN THE YANGTZE RIVER YU Gong2liang, LIU Jun, XU Yun2gan and CHANGJian2bo ( Institute of Hydrobiology, The Chinese Acabemy of Sciences, Wuhan ) Abstract :From 1997 to 2001, assessment on the annual abundance of benthonic fishes which prey on eggs of Chinese sturgeon were undertaken through commercial fisheries surveys in the reach below the Gezhouba Dam where the spawning ground of Chinese sturgeon located in the Yangtze River. Eleven species of benthonic fishes were confirmed to be egg2predators through the examination of gut contents. The dominant species of egg2predatory fishes were Coreius guichenoti, C. heterodon and Pelteobagrus vachelli. First of all, by applying Jones Length2based cohort analysis, annual abun2 dance of C. heterodon was estimated with fishing data collected in springs and autumns. Then, abundance of the rest egg2predatory fishes were counted according to the quantitative ratios of them to C. heterodon in catches. Summarily, annual abundance of egg2predatory fishes fluctuated from to with an average of individuals within the research period. Due to as2 semblage for preying on eggs, abundances of egg2predatory fishes were obviously higher in course of egg deposition of Chinese sturgeon, and numbered from to with an average of individuals annually. It was estimated also that approximately eggs, correspond2 ing to the fecundity of 4 females, were eaten by egg2predatory fishes daily in the egg deposition peri2 ods of Chinese sturgeon. Key words : of egg2predatory fish ; Length2based cohort analysis ; Coreius heterodon ; Spawning ground of Chinese sturgeon