GROWTH AND REPRODUCTIVE CHARACTERISTICS OF ANCHERYTHROCULTER KUREMATSUI KIMURA

Ancherythroculter kurematsui Kimura is an endemic fish of the Yangtze River, and lives only in the upperreaches of the Yangtze River basin, mainly in Sichuan Province and Chongqing City, China. As an endemic genus, theAncherythroculter Yih et Woo is thought to be important in fish taxonomy and zoogeography studying. Growth is animportant aspect of the ecology and life history of fish, and quantification of growth is frequently a crucial part of fisheriesresearch and management. Unfortunately, few studies have been conducted to describe the growth and reproductivecharacteristics of A. kurematsui. The purpose of this study was therefore to determine age structure and growth characteristicsof A. kurematsui. A total of 540 specimens of A. kurematsui were collected during May to November 2008 fromthe Chishui River, a first-order tributary of Yangtze River. The population age structure and growth characteristics of A.kurematsui were studied. The results showed that the population of A. kurematsui had a relatively simple age structurewhich only contains 4 age classes. The age structure of A. kurematsui was dominated by young individuals, and over95% of the total were age 2 and age 3. Body length range of the population was 81—182 mm, mainly between 100 mmand 160 mm (88.21%), and body weight ranged from 8.7 g to 84.7 g, mainly between 20.0 g and 50.0 g (69.93%). Thetotal sex ratio (♀∶♂) of the population was 1.30∶1, which showed there were much more female individuals thanmale. The fish scale is a kind of appropriate material for age determination; the new annual rings on scales formedmainly in August and September, and all new annual rings were formed before November. The radii of scale (from focusto the flank) took on linear relationship with body length, which could be used for body length back-calculation. Therelationship between body length and radii of scale was described as L=0.0169R+0.0815 (r=0.9305, n=487). There waslittle evidence of differences between sexes. The body length and body weight was in the relation of power function; therelationship of body length to body weight for A. kurematsui could be expressed as W=0.00004 L2.8103 (R=0.9727,n=487). Growth of A. kurematsui took on a constant speed style, which could be described with Von Bertalanffy equation.The growth equation of body length and body weight were estimated as Lt =217.38 (1 ? e?0.2867 (t+0.757) ) and Wt =118.151 ? e ?0.2867(t+0.757)2.8103, respectively. The supreme body length was 217.38 mm, the supreme body weight was118.15 g, the growth parameter was 0.2867 and the theoretical body length zero-point was ?0.7570. The body weightgrowth inflexion point was 2.85, with the corresponding body length of 140.09 mm and body weight of 34.37 g. The fastgrowing period was in the period of 1—2 year old. The average maturing factor of female showed just a peak in Juneduring a year. The absolute fecundities of the matured females varied from 950 to 8655 eggs, and (3087.90 ±1602.15)eggs on average. The relative fecundity to body weight varied from 66.08 to 197.67 eggs/g, with an average of (116.49±32.05) eggs/g. The egg diameter distribution in the ovary was unimodal at mature stage indicating that A. kurematsuiwas a total spawner as opposed to a batch spawner. The results of this study provided important information that the A.kurematsui was being seriously threatened by over-fishing and other reasons. For conservating the resource of A. kurematsui,some measurements must be taken. The conservation strategies include limit fishing biomass, set bidding-fishing periods and protect the key habitat.