ABSTRACT
In order to investigate the role of otolith carbon (δ13C) and oxygen (δ18O) stable isotopes in identification of freshwater fish stocks, otolith δ13C and δ18O of cultured Schizothorax kozlovi at different ages were measured by stable isotope mass spectrometer. The relationships between otolith δ13C / δ18O and environment were discussed. The results showed that δ13C and δ18O values of S. kozlovi at age 1+ were not significantly correlated with otolith mass, but both were significantly different between lapillus and asteriscus. The average lapillus δ13C and δ18O values of S. kozlovi at different ages were (-9.58±0.06) and (-8.33±0.17), respectively. There was no significant difference of lapillus δ13C and δ18O between the sexes, but with significant difference among diffe-rent ages. The correlation of δ13C with δ18O was an effective method in identification of different culture stocks of S. kozlovi, which indicated the isotopic signatures of otolith could be used as a method to identify freshwater fish stocks.
Subject(s)
Carbon , Fishes , Oxygen Isotopes , Animals , Carbon Isotopes , Isotopes , Mass Spectrometry , Nitrogen Isotopes , OxygenABSTRACT
Under the conditions of simulated micro-habitat in laboratory, and by using experimental ecological methods, this paper evaluated the suitability index (HSI) of young Procypris rabaudi for habitat factors (substrate, light intensity and water depth). The habitat suitability models of the young P. rabaudi were established, and the minimum habitat area of the young P. rabaudi was estimated. The young P. rabaudi preferred the habitats with the gravel diameter from 10 to 15 cm, light intensity from 0.2 to 1.8 lx, and water depth from 0 to 15 cm (distance from the bottom of the tank). The three suitability index models of the substrate, light intensity and water depth for the young P. rabaudi were SI(s) = 1.7338e(-0.997x)(SI(S) is the suitability index of substrate, and x is the gravel diameter; R2 = 0.89, P < 0.01), SI(L) = 3.0121e(-1.339x)(SI(L) is the suitability index of light intensity, and x is the light intensity; R2 = 0.93, P < 0.01), and SI(W) = 2.4055e(-1.245x)(SI(W) is the suitability index of water depth, and x is the water depth; R2 = 0.97, P < 0.01), respectively. Arithmetic mean model HSI = (SI(S)+SI(L)+SI(W))/3 was most available for the estimation of the habitat suitability of young P. rabaudi. A total of seven groups of young P. rabaudi which established and maintained a relatively stable habitat area range were found. This habitat area ranged from 628 to 2015 cm2, with an average of 1114 cm2.
Subject(s)
Carps/physiology , Ecosystem , Models, Biological , Animals , Behavior, Animal , ChinaABSTRACT
A total of 36 females and 21 males of Chinese sturgeon Acipenser sinensis were caught in 1998-2004 excluding 2002 to study the characteristics of their reproductive biology and the effect of their artificial propagation. The results showed that the body length (BL), body mass (BM) and age of the females were 240-320 cm, 140-432 kg, and 15-30 years, and those of the males were 153-284 cm, 70-244 kg and 12-26 years, respectively. The inducing rate was 93.1% for females and 100% for males, and the ova had 7 different colors. The absolute fecundity was 200,000-590,000 eggs, with an average of 358,000 eggs, and the relative fecundity to BM was 820-3,020 eggs per kg, with an average of 1,590 eggs per kg. The sperm had 4 different colors. The absolute sperm quantity obtained from one male was 1,000-5,952 ml, with an average of 2,597.8 ml, and the relative sperm quantity to BM was 1.25-31.24 ml . kg(-1), with an average of 13.3 ml . kg(-1). During the study period, the average fertilization rate in artificial propagation was 63.7%, and the hatching rate was 48.1%, with 4,762,000 fry obtained. Compared with the data in 1976, the natural reproductive capacity of the Chinese sturgeon broodstocks declined greatly.
