The spawning and well-being of fish in an ecosystem are closely linked to climatic cues, viz., temperature and rainfall. Reduced fitness can affect the reproductive performance and lead to skipped spawning. Benchmarking the threshold fitness required for a fish population to achieve readiness for spawning, and understanding how climatic parameters influence the fitness will aid in predicting the fate of its reproductive success in future climatic conditions. This study determined the threshold condition factor pre-spawning fitness (Kspawn50) at which 50% of the female Channa punctata population can be deemed fit for spawning. The optimal climate within which pre-spawning fitness is attained by this species under Indian climatic conditions was also identified. The study was conducted from June 2015 to September 2016, covering two spawning seasons (June–August) in a Gangetic floodplain wetland of West Bengal, India. The non-parametric Kaplan–Meier method (survival fit) was used for estimation of pre-spawning fitness. “Ready to spawn” females were classified based on binary coding of the gonadal maturity stages. The thermal and precipitation range within which spawning fitness is achieved was identified by using the locally weighted smoothing technique. Female C. punctata pre-spawning fitness (Kspawn50) ranged from 1.26 to 1.39 with an estimated median of 1.29 units. Temperatures between 29 and 32 °C and rainfall above 100 mm were conducive to attaining the requisite pre-spawning fitness in C. punctata. This is the first study benchmarking the pre-spawning fitness and optimal climate for C. punctata. Understanding spawning requirements can inform the climate change–induced impacts on reproductive plasticity and evolutionary adaptations of snakeheads in the Ganga river basin.

中文翻译：

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对来自印度西孟加拉邦恒河泛滥平原湿地的斑点蛇头鳢 (Bloch, 1793) 的产卵前适应性和最佳气候进行建模

生态系统中鱼类的产卵和健康与气候线索密切相关，即温度和降雨量。适应性降低会影响繁殖性能并导致跳过产卵。对鱼类种群达到产卵准备所需的阈值适应性进行基准测试，并了解气候参数如何影响适应性将有助于预测其在未来气候条件下繁殖成功的命运。本研究确定了产卵前适合度 (Kspawn50) 的阈值条件因子，在该条件下，50% 的雌性 Channa punctata 种群可被视为适合产卵。还确定了该物种在印度气候条件下获得产卵前适应性的最佳气候。该研究于 2015 年 6 月至 2016 年 9 月进行，涵盖印度西孟加拉邦恒河漫滩湿地的两个产卵季节（6 月至 8 月）。非参数 Kaplan-Meier 方法（生存拟合）用于估计产卵前的适应度。“准备产卵”雌性基于性腺成熟阶段的二进制编码进行分类。通过使用局部加权平滑技术确定产卵适合度达到的热和降水范围。雌性 C. punctata 产卵前适应度 (Kspawn50) 介于 1.26 至 1.39 之间，估计中值为 1.29 个单位。29 到 32 °C 之间的温度和 100 毫米以上的降雨量有利于 C. punctata 达到必要的产卵前健康。这是第一项对 C. punctata 产卵前适应性和最佳气候进行基准测试的研究。