| The identification in the life-history characteristics of fish and their response to environmental conditions is the basis for protecting fish species diversity and sustainably using fishery resource. In this study, the life history of two Danioninae fishes, i.e., Opsariichthys bidens and Zacco platypus was investigated using the specimens collected in the Qingyi Stream from May 2009 through April 2010. The whole life-history variables involved annulus characteristic, annulus formation, age structure, length-weight relationship, growth equation, grow rate and accelerating rate, growth performance, spawning timing, first sexual maturity, reproductive investment, and so on. In addition, the influence of environmental press on the life history of these two species was discussed. Our aim was to further collect some information on the basic biological traits for the two species. Of course, our results will offer the scientific basis for the protection and management of the fishery resources in the Qingyi Stream. The main results were as follows:1. Age. Scales were used for age determination. For O. bidens in the Qingyi Stream, their annuli show the typical incising type and were formed during March and April. The largest longevity of the females and males were age 5 and 4, respectively. The relative abundance of each aging group was 8.77% (age 1), 57.02% (age 2), 31.58% (age 3), 1.75% (age 4), and 0.88% (age 5) for the females; and 7.97% (age 1), 47.10% (age 2), 39.13% (age 3), 5.80% (age 4), respectively. For Z. platypus in the Qingyi Stream, their annuli show spacing, incising, and space-incising types and were formed during March. The largest longevity of the females and males were both age 3. The relative abundance of each aging group was 48.08% (age 1), 50.96% (age 2), and 0.96% (age 3) for the females and 45.33% (age 1), 51.87% (age 2), and 2.80% (age 3) for the males, respectively.2. Growth. For O. bidens in the Qingyi Stream, L–W equations were W♀= 8×10-6L3.05 (R2 = 0.89, N = 119) and W♂= 5×10-6L3.15 (R2 = 0.96, N = 141). They could be combined as W = 6×10-6L3.12 (R2 = 0.93, N = 260) because no significant difference was observed between both sexes (ANCOVA, P > 0.05). L–R equations were L♀= 0.04R + 38.02 (R2 = 0.52, N = 119) and L♂= 0.04R + 30.95 (R2 = 0.56, N = 141). They could also combined as L = 0.04R + 33.35 (R2 = 0.55, N = 260). The von Bertalanffy growth functions were Lt♀= 246.31 (1-e-0.26(t-0.36)) and Lt♂= 243.97 (1-e-0.31(t-0.57)), with the combining function being Lt = 302.38 (1-e-0.18(t-0.07)). The age at inflection point of weight-growth was age 4.65 for the females and 4.27 for the males, respectively. For Z. platypus in the Qingyi Stream, L–W equations were W♀= 5×10–6L3.15(R2 = 0.84,N = 104)和W♂= 7×10–6L3.09 (R2 = 0.73,N = 214). They could be combined as W = 6×10–6L3.10 (R2 = 0.76,N = 318), because no significant difference was observed between both sexes (ANCOVA, P > 0.05). L–R equations were L♀= 0.03R + 38.84 (R2 = 0.50,N = 104) and L♂= 0.03R + 34.99 (R2 = 0.62,N = 214). Significant difference was observed between both sexes(ANCOVA,P < 0.05)3.Reproduction. Sex ratio (female: male) was 1: 1.18 for O. bidens, not significantly different from 1: 1 (χ2 = 0.93, P > 0.05), and 1: 2.04 for Z. platypus, significantly different from 1: 1 (χ2 = 20.54, P < 0.01). Based on the monthly changes in gonado-somatic index (GSI), O. bidens and Z. platypus both spawned during the period from April through July. Fifty percentages of individuals for O. bidens got the first sexual maturity at age 2, with the total length of 118.08 mm for the females and 126.52 mm for the males, respectively. For Z. platypus, they got their 50% maturity at age 2 too, with their total length of 97.80 mm for the females and 105.69 mm for the males, respectively. The absolute fecundities (AF) were 1818±705 eggs for O. bidens and 758±362 eggs for Z. platypus. In addition, their relative fecundities (RF) were 102.15±60.67 (O. bidens) and 77.38±22.15 (Z. platypus) egg/g, respectively. |
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