长鳍金枪鱼全生命史动态能量收支预测模型

A full lifecycle dynamic energy budget model for Thunnus alalunga

摘要:

目的 为统一长鳍金枪鱼生长、繁殖、衰老死亡等过程，本研究基于动态能量收支预测理论，以建立长鳍金枪鱼全生命史动态能量收支预测模型。方法 利用长鳍金枪鱼的生长、繁殖等数据，估计了动态能量收支预测模型参数，构建了其全生命史动态能量收支预测模型。结果 ①动态能量收支预测模型能较好拟合长鳍金枪鱼全生命史的生长过程、估计长鳍金枪鱼的潜在年繁殖力，并使长鳍金枪鱼的生长、性成熟、产卵、衰老死亡等过程相互联系、内在统一；②长鳍金枪鱼的生长在性成熟前后存在两个不同阶段，其体长-体重关系将受这两个群体样本比例的影响而不同，采用一个幂函数拟合体长-体重关系不合适；③衰老死亡随年龄变化差异较大，长鳍金枪鱼自然死亡系数假设应考虑随年龄或体长变化的影响。结论 尽管受观测数据缺乏的影响，动态能量收支预测模型的参数估计存在较大的不确定性，但动态能量收支预测模型能有效拟合长鳍金枪鱼生长、繁殖、衰老死亡等过程，使其相互联系、内在统一，体现了其应用价值。本研究结果能为长鳍金枪鱼的生长研究及其资源的合理评估提供科学支持。

Abstract:

Biological parameters, including growth, reproduction, and natural mortality, are critical factors influencing the stock assessment of albacore tuna (Thunnus alalunga). However, these parameters are often derived from disparate data sources, lacking internal consistency and uniformity. Moreover, they fail to cover the full lifecycle of T. alalunga, leading to uncertainties in stock assessment results. To address this, we constructed a full lifecycle dynamic energy budget (DEB) model for T. alalunga based on the DEB theory and available growth and reproduction data. Model parameters were estimated accordingly. The results demonstrated the following: ① The DEB model accurately fitted the growth process of T. alalunga throughout its life history, estimated its potential annual fecundity, and integrated the processes of growth, maturity, spawning, and mortality. Notably, the model provided a growth equation for T. alalunga larvae without requiring age and length data, which the von Bertalanffy growth function (VBGF) cannot accurately provide. ② According to DEB theory, the growth of T. alalunga exhibitd two distinct stages before and after sexual maturity. Before maturity, energy allocated to maturation is dissipated and not used for body weight gain. In contrast, after maturity, energy was stored for reproduction and also contributed to weight gain. Consequently, the length-weight relationship was influenced by the proportion of mature and immature individuals in the sample. Our results indicated that using a single power function to fit the length-weight relationship for both stages is inappropriate. ③ The natural mortality coefficient was typically assumed to be constant (e.g., 0.3/a) in T. alalunga stock assessments. However, our findings revealed that aging mortality varies significantly with age or length. Given the substantial impact of this assumption on stock assessment and management, we suggested that the natural mortality coefficient for T. alalunga should account for age- or length- dependent variation. Although parameter estimation in the DEB model was subject to uncertainty due to limited observation data, the model effectively and accurately integrated the growth, reproduction, and aging mortality processes of T. alalunga. This highlighted the valuable application of DEB models in such studies. The findings of this study provided scientific support for the growth analysis and improved stock assessment of T. alalunga.