甲壳类年龄鉴定方法研究进展

甲壳类特有的蜕壳现象,使其能够记录年龄信息的外骨骼周期性消失,因此甲壳类的年龄鉴定一直未得到较好的解决。年龄鉴定是评估甲壳类渔业资源的基础,鉴定甲壳类年龄的方法主要有饲养法、标记重捕法、体长频度法、脂褐素分析法、放射性同位素分析法和硬组织生长纹分析法。饲养法、标记重捕法和放射性同位素分析法较准确,然而由饲养法得到的数据不适用于实际野生环境,放射性同位素分析法花费较高,因此,这两种方法都存在较大的局限性。应用最广泛的标记重捕法和体长频度法也存在不足之处。相对于体长频度鉴龄技术而言,脂褐素分析法优势明显,但是对劳动强度和技术要求高。硬组织生长纹分析法是最近几年出现的鉴龄技术,也存在人为主观性较强等不足。本文对甲壳类年龄鉴定的方法进行了总结回顾,将不同鉴定方法进行比较,分析优缺点,以期为开展甲壳类资源评估与管理提供基础。

Advance on methods for the age identification of crustaceans

Crustaceans are widely distributed in the oceans worldwide including the polar region.Their high species diversity and large quantity make them become an important part of fishery resources.Age is the essential part of the aquatic animal life history study, as well as one of the most important parameters in the fish population dynamics models and fishery resources evaluation.Most aquatic animals'' age can be identified by counting the growth bands in the hard tissue.However, crustaceans grow up through molt, leading to the original shells replaced by the new ones, which causes the periodic record of their calcified structures disappearing.Therefore, the age identification of crustaceans has never been perfectly accomplished.Main existing methods for the crustaceans'' age identification are rearing in captivity, tagging and recapture, size-frequency analysis, lipofuscin-based ageing, radioisotope analysis and calcified structures analysis.Rearing in captivity is the most accurate and reliable method for the crustaceans'' age identification.Tagging and recapture method is more direct and effective.Size-frequency analysis method is most commonly used by early scholars.In this method, crustaceans'' body length data are firstly classified into different body length groups, and then converted into age groups by Von Bertalanffy growth equation or other equation models.For the relationship between the morphological characteristics of crustaceans and their ages can not be established, lipofuscin-based ageing method is applied for the age identification of many invertebrates.Lipofuscin is related with cells aging, which is one of the most obvious age tags in cells.Radiometric ageing method is applicable to determine the crustaceans'' shell age and the results are also comparatively accurate.This method is generally used for long-lived species based on the long element half-life, but the element half-life measuremeat requires special equipment so the cost for this method is very high.So it is less used.Calcified structures analysis is a kind of method to count the growth bands that generate in the crustaceans'' eye stalk or gastric when they grow.Calcified structures analysis is the most accurate method, and the needed hard tissue is easy to extract.The calcified structure analysis method provides a new way for the direct age identification of crustaceans, and its application prospect is extensive.Rearing in captivity method, tagging and recapture method and radiometric ageing method all are comparatively accurate.However, the data obtained from the rearing in captivity method is not applicable in the natural environment, and the radiometric ageing method is very expensive.So both methods have limitations in practice.The tagging and recapture method and size-frequency analysis method which are most widely used also have their disadvantages.Compared to size-frequency analysis method, lipofuscin-based ageing method has obvious advantages, but the labor intensity and technical requirements are high.Calcified structures analysis method is the age identification technology that has appeared in recent years, and the age is identified by directly counting the number of growth bands in crustaceans'' hard tissue.This method is a good solution to the lack of direct and effective crustaceans'' age identification, and provides the theoretical basis for the assessment and management of crustacean fishery resources, but there are also some disadvantages like strong man-made subjectivity.In this paper, the methods of crustaceans'' age identification are reviewed and summarized, the different methods are compared and analyzed to get the advantages and disadvantages, so as to provide the basis for the assessment and management of crustacean fishery resources.