Otolith Shape,Microchemistry And Ageing In Mackerel Icefish (Champsocephalus Gunnari)

Antarctic icefish species are widely distributed in Antarctic waters, it’s plays an important role in the Antarctic fish species. So the growth state of the research is particularly important. The otolith is calcium carbonate in teleost fishes in the inner ear, it is play a part in sound reception and balance. It’s have a highly species specific differences between the morphology, concentric arrangement of growth ring can be used to the age determination and to study the growth process, and otolith the deposition process by influence factors of water elements, temperature and salinity, otolith composition often can used as biological labels reflect the living environment of fish, and to effectively understand the life history information.In this study, firstly we used otolith to analysis shape parameters and the Fourier analysis method to divided two Antarctic icefish（Champsocephalus gunnari, Chionobathyscus dewitti）.study on the Champsocephalus gunnari age and growth characteristics and its identification technology and method of age determination, by LA-ICP-MS on otolith micro area elements are analyzed to compared the different age stages of elemental composition. Through the research, the main conclusions are as follows:（1） For the otolith size, Champsocephalus gunnari otolith length range is 2.64-3.62 mm, and Chionobathyscus dewitti the otolith length range is 1.23-2.92 mm. Two kinds of fish body long and otolith morphology parameters had significant correlation, between two species of Antarctic icefish the morphological parameters have significant difference（2） For Champsocephalus gunnari and Chionobathyscus dewitti otolith shape of Fourier and discriminant analysis showed that, the selection of the six Fourier harmonic value of discriminant analysis, two species of discriminant functions were: Champsocephalus gunnari : Y=1018.02×D1-373.046×B3-256.492×A4-703.631×B9+6772.693×A16-5261.890×A18-416.675 Chionobathyscus dewitti : Y= 1141.332×D1-477.856×B3-380.728×A4-884.742 B9+7901.120×A16-6215.346×A18-521.775。（3） To Champsocephalus gunnari age and growth of otolith, it should be adopted on cutting grinding. Observe the sections under reflected light, read on the abdominal side rotiform otolith opaque zone（the reflected light is dark）.（4） The high precision of age interpretation can be observed for aging estimation based on sectioned otolith. The total percent of agreement（TC）, coefficient of variation（CV） and the average percent error（APE） are 56.42%, 8.11% and5.73% respectivel（5） The VBGF function of Champsocephalus gunnari is as follows: length L_t= 38.7509(1-e^{-0.2759（+1.5123）}) weight (W_t= 361.2601(1- e^{-0.2759（+1.5123）})^3.1899（6） Champsocephalus gunnari growth rate have decreased with the growth of the age, First of all,it is rapidly, gradually slowed down, finally tends to zero; growth rate of body weight and growth acceleration is more obvious inflection point, at the growth inflection point, by the formula the weight growth inflexion age is 2.69, the inflection point weight is 180.83 g, body length is 26.60 cm.（7） By LA-ICP-MS on otolith,the total measured 47 kinds of chemical elements, between different gender variance analysis results show that the elements do not exist significant differences except Co and Sr, at t the different age analysis shows that: in addition to the Ba, Mg, Sr and other elements Li, Na, Cu, Zn, Fe, Ni and Ca don’t have significant difference.