泉吉河中青海湖裸鲤的繁殖生物学特征

付生云; 祁洪芳; 罗颖; 汪鹏程; 田少锋

doi:10.14012/j.jfr.2024091

泉吉河中青海湖裸鲤的繁殖生物学特征

Reproductive biology of Gymnocypris przewalskii in Quanji River, Qinghai Province

摘要

摘要:
背景 2023年对标记了被动集成应答器（PIT）芯片的青海湖裸鲤（Gymnocypris przewalskii）溯河群体进行监测，发现不同河道的溯河群体有分组现象。
目的研究青海湖裸鲤群体出现洄游分组现象后的繁殖生物学特征。
方法 2023年5月至8月在泉吉河采集了552尾青海湖裸鲤样本，从性腺采集与处理、初次性成熟体长、卵径分布、性腺指数、繁殖力及年龄鉴定等方面进行繁殖生物学研究。
结果采集的青海湖裸鲤样本平均体长为（224.5 ± 20.4）mm，平均体质量为（179.5 ± 62.1）g，其中雌鱼有253尾，平均体长为（240.4 ± 28.7）mm，平均体质量为（140.9 ± 76.9）g ；雄鱼有299尾，平均体长为（188.8 ± 63.0）mm，平均体质量为（159.3 ± 55.6）g。雌鱼的年龄由4龄~11龄7个年龄段组成，以4龄、5龄为主，占比为78.6%；雄鱼的年龄由3龄~6龄4个年龄段组成，以3龄、4龄为主，占比为86.5%。根据L₅₀的方法，求得雌性L₅₀方程为 L_50=1/1+\texte^-0.65（L_\rmmid-173.1），初次性成熟体长为167.5 mm；雄性 L_50=1/1+\texte^-0.98（L_\rmmid-157.2），初次性成熟体长为154.6 mm。雌鱼卵巢发育Ⅱ期的平均卵径为（0.98 ± 0.05）mm，Ⅲ期为（1.45 ± 0.02）mm，Ⅳ期为（1.63 ± 0.05）mm，Ⅴ期为（1.88 ± 0.05）mm。青海湖裸鲤的繁殖期集中在6月至7月，属于溯河产卵类型。雌鱼性腺指数（GSI）自5月起逐渐增大，7月达到高峰，8月开始下降；绝对繁殖力为720.0~16080.0粒，平均值为（4261.4 ± 3343.4）粒；相对繁殖力为9.1~131.4 粒/g，平均值为（29.4 ± 10.3）粒/g；绝对繁殖力（AF）与体长（L）呈对数相关，AF = 14985lnL−76978（R² = 0.7688，P<0.0001）；绝对繁殖力（AF）和体质量（W）呈对数相关，AF = 5078.9lnW−20610.0（R² = 0.8480，P<0.0001）。雌鱼体长（Y_♀）与体质量(W_♀)具有较强的相关性（R² = 0.9085，P<0.0001），Y_♀ = 0.0153W_♀² −5.2191W_♀ +516.6300；雄鱼体长（Y_♂）与体质量（W_♂）具有较强的相关性（R² = 0.8653，P<0.0001），Y_♂ = 0.0015 W_♂²−0.2068W_♂ +53.7840。青海湖裸鲤的微耳石磨片为不规则的马蹄形，其中心区在透射光下较暗，接近圆形；中心区外围在透射光的照射下分布有明暗相间的不规则环形亮带。
结论青海湖裸鲤溯河群体出现分组现象后，泉吉河溯河群体未出现明显的特征变化。本研究为青海湖裸鲤的保护和可持续利用提供科学依据。

Abstract:
Background During 2023, monitoring efforts using passive integrated transponder (PIT) tags revealed intriguing grouping behaviors within the spawning populations of Gymnocypris przewalskii in Qinghai Lake.
Objective This study aimed to investigate the reproductive biology characteristics of G. przewalskii populations following the emergence of grouping phenomena.
Methods Between May and August 2023, a sample size of 552 G. przewalskii specimens was gathered from Quanji River. Extensive reproductive biological analyses were performed, including examination of gonadal tissue, determination of initial sexual maturity lengths, assessment of egg diameter distributions, calculation of gonadosomatic indices, estimation of fecundity, and establishment of age structures.
Results The mean body length of the sampled G. przewalskii was (224.5±20.4) mm, with an average body mass of (179.5±62.1) g. Within this cohort, 253 female individuals averaged (240.4±28.7) mm in body length, and (140.9±76.9) g in body mass, while 299 males measured (188.8±63.0) mm in body length, and weighed (159.3±55.6) g on average. Females spanned ages 4 to 11 years, with 4 years old and 5 years old predominating at 78.6%, whereas males ranged from 3 to 6 years old, with 3 years old and 4 years old comprising 86.5% of the sample. Utilizing the L₅₀ methodology, the onset of sexual maturity was established at 167.5 mm for females and 154.6 mm for males. Average egg diameters across stages Ⅱ−Ⅴ were (0.98±0.05) mm, (1.45±0.02) mm, (1.63±0.05) mm, and (1.88±0.05) mm, respectively. Spawning activity peaked in June and July, classifying G. przewalskii as anadromous spawners. Female maturity coefficients rose steadily from May, peaking in July before declining in August. Absolute fecundity varied between 720.0 and 16080.0 grains per female, averaging (4261.4±3343.38) grains, with relative fecundity ranging from 9.1 to 131.4 grain/g and averaging (29.4±10.3) grain/g. For females, absolute fecundity (AF) was logarithmically related to body length (L), with the equation AF=14985lnL−76978 (R²= 0.7688, P<0.0001 ); absolute fecundity (AF) was also logarithmically related to body weight (W), with the equation AF = 5078.9lnW−20610.0 (R²= 0.848 0, P<0.0001 ). Female body length (Y_♀) had a strong correlation with body weight (W_♀) (R² =0.9085, P<0.0001 ), with the equation Y_♀=0.015 3W_♀²−5.2191W_♀+516.6300; male body length (Y_♂) also had a strong correlation with body weight (W_♂) (R²=0.8653, P<0.0001 ), with the equation Y_♂=0.0015W_♂²−0.2068W_♂ +53.7840. Otolith sections of G.przewalskii were irregular horseshoe-shaped, with the central area appearing darker under transmitted light, nearly circular; the outer area of the central zone exhibited irregular alternating light and dark rings under transmitted light.
Conclusion After the grouping phenomenon appeared in the migrating population of G. przewalskii in Qinghai Lake, the migrating population in Quanji River did not show obvious characteristic changes. This study provides scientific evidence for the conservation and sustainable use of G. przewalskii in Qinghai Lake.

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