| Through literature review methods, fish and amphibians age determination methods were reviewed.261Chinese giant salamander samples were collected from a breeding base in Zhejiang Province, from June2012to March2014.1to6age groups of Chinese giant salamander were included in the sample. Body length and weight of all Chinese giant salamanders were measured, bones were removed and brought back to the laboratory, and bones of different parts were compared. Application of cryo-sectioning technique was well-researched with the toe. Age determination methods were explored, with the body length and weight of Chinese giant salamander. Growth characteristics of Chinese giant salamander were described.2-year-old Chinese giant salamander was used as experimental material. Vertebrae, otoliths, phalanges bones were observed and sliced. Otolithes, which were small and brittle, were crumbled during the experiment, the section was not successful. Spine had not been sectiond, because it was very hard, although they were easy to be removed. A total of17toes and metatarsals in the feet of the Chinese giant salamander, were sliced and stained. Experimental results show that a total of7bones in one foot of the Chinese giant salamander, including the second phalanges bones of all the toes, and third phalanges bones of the third toe and the fourth toe, could identify the age of Chinese giant salamander. The second phalanges bones of the third toe and fourth toe were the best material for age determination, because the diameter was large, the bone marrow cavity was small and bone area was large.5-year-old Chinese giant salamanders were used as experimental material. Experimental procedure was:rinsing formalin, clearing muscle, dissolving calcium, slicing, staining. Each experimental procedure had been explored seriously. The experimental results showed that:with2%sodium hydroxide, which was boiled for a short time, the muscle and connective tissue was removed. Calcium can be dissolved by2%to6%nitrate and3%and4%nitrate were the best. Sections, which had not been dissolved, could show the ring in a short time when the calcium was dissolved again. Sections both stained or not, could show rings clearly. Sections, which were stained, could show the marrow cavity clearly but show the rings as usual. Dyeing was not required.Growth rings were rings, which were alternating loose and tight, bright and dark. Black rings were growth rings, which was dense. Growth rings could be used to identify the age, because their characteristics were obvious. No growth rings were found in one-year-old giant salamander, which had not experienced hibernation Growth rings were found in the two-year-old Chinese giant salamander, which had experienced hibernation, and the growth rings were found once a year from then on. Growth rings were probable produced when the Chinese giant salamander hibernated. Growth rings diameter was analyzed, which show a linear growth law shape. The main factors that leaded to the formation of growth rings were the food and temperature.Body length of Chinese giant salamander, at the age of1-5, was analyzed. Equation of body length and age, were fit. Frequency distribution of body length was analyzed. Age of Chinese giant salamander, was calculated using the results of analysis. Actual age and estimated age of Chinese giant salamander, were compared. Using body length method, age determination accuracy was analyzed.1-year-old Chinese giant salamander body length≤23.33cm, with an average of18.64cm;Body length ranges and averages of2-year-old Chinese giant salamander was27.47～36.61cm and32.18cm.Body length ranges and averages of3-year-old Chinese giant salamander was38.03～47.15cm and46.05cm. Body length ranges and averages of4-year-old Chinese giant salamander was48.68～54.49cm and49.43cm. Body length ranges and averages of5-year-old Chinese giant salamander was58.17～69.88cm and63.24cm. Length data between different ages had no overlap. Body length differences between adjacent ages were average, except for3-year-old and4-year-old Chinese giant salamander. Analysis of variance showed that:body length differences of the Chinese giant salamander between the different groups were extremely significant. Length data of3years and4years of age, has significant difference, other body length data between adjacent age groups, has extremely significant. Relationship between body length and age was a linear equation. The equation is y=10.646x+9.97, b= 10.64, R2=0.9728. Body length kept on growing, will not abort because of sexual maturity. Identification of Chinese giant salamander age, with the range of body length, we could find some of the age of the sample had not been identified, the identification rate was63%, and the accuracy was79%; identification of Chinese giant salamander age, by the using of body length-age regression equations, we could find identification rate was100%, the accuracy was71%, and some ages of Chinese giant salamander were underestimated; identifiable rate and accuracy of age identification, by the using of the frequency distribution of body length, were86%and61%.Body weight of1-5year’s Chinese giant salamander were analyzed. Body weight ranges and averages for each age group were:1-year-old,≤55.40g and40.47g;2years old,168.37～246.99g and199.19g;3-year-old,437.85～674.02g and626.94g; Four years old,699.43～931.46g and783.36g;5-year-old,1200.80～2013.56g and1691.45g. Body weight between different ages had no overlap. Speed of body weight gain became faster and faster. Trends of body weight gain keep on growing. As the result, analysis of variance showed that body weight among different age had significant difference (P<0.05). Body weight difference between adjacent age group had significant difference, in addition to3years old and4years old Chinese giant salamander. Curve of the body weight and age was the exponential function. Equation of the regression was y=25.947e0.8835x, b=25.947, R2=0.8835, P<0.01. Identifiable rate and accuracy of age identification, with the range of body body weight, were74%and63%; Identifiable rate and accuracy of age identification, by the using of body weight-Age regression equation, were100%and60%.Age determination methods both direct and indirect were analyzed. Method using the toe section was the most accurate. Methods by using the body length and weight data were convenient but required a large number of samples and analyzed methods, otherwise, the result would not be accurate enough. Growth rings formed when the Chinese giant salamander hibernates. Without hibernate phenomenon, growth rings would not form. Breeding conditions needed to be considered when we identificated age using the toe. |
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