Breeding strategy of Acrossocheilus fasciatus in the Puxi Stream of the Huangshan Mountain

摘要

Breeding strategies of Acrossocheilus fasciatus were studied from 592 specimens collected monthly during May 2007 and April 2008 in the Puxi Stream of the Huangshan Mountain.Sex ratio of the studied population was 0.90∶1(♀∶♂),not significantly different from 1∶1.Both sexes reached their first sexual maturity at age 2(the second calendar year of their birth).Fifty percent of females and males reached maturity at a total length of 69.75 mm and 69.36 mm respectively,and the minimum total length was 61.54 mm and 58.96 mm,respectively.Based on the monthly changes in gonado-somatic index and egg-development process,the breeding season of the population was from May to August,with one obvious interval(in June)occurring in the breeding activity for the females.The nonsynchronous development of oocytes observed in mature ovaries indicated that A.fasciatus is a batch spawner.Absolute fecundity of A.fasciatus ranged from 308 to 2002 eggs with a mean of 857 eggs,increased significantly with total length,and was significantly different among three age groups.Relative fecundity ranged from 38.63 to 71.70 egg/g with a mean of 53.29 egg/g,and was not significantly different among the three age groups.It was suggested that these reproductive characteristics were adaptive strategies for A.fasciatus to acclimatize to lotic water where environmental factors were unstable but predictable.