Abstract

Fisheries science and management is founded upon the Beverton–Holt theory of fish stock demography. The theory uses age as the structuring variable; however, there are several reasons to use body size as the structuring variable. Most of the processes that affect a fish are determined by its body size rather than its age: consumption, mortality, maturation, fecundity, fish gear selectivity, etc., and measurements of body size are easy, accurate, and abundant. Here, I review size-based theory of a fish stock and compare it to classic age-based theory. I show that size- and age-based demography are equivalent representations of demography. However, size-based theory is axiomatic, which leads to a deeper theory with two advantages: predictions need fewer parameters than age-based theory and the theory connects directly to life-history traits. The connection with traits makes size-based theory particularly useful for data-poor application and facilitates evolutionary calculations. I compare age- and size-based theories for fisheries impact and stock assessments and provide a perspective on the challenges and future of single-stock theory.

中文翻译：

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基于规模的渔业咨询理论

摘要

渔业科学与管理建立在贝弗顿-霍尔特鱼类种群人口统计理论的基础上。该理论以年龄为结构变量。但是，将身体尺寸用作结构变量有多种原因。影响鱼类的大多数过程都取决于鱼的体型，而不是鱼的年龄：食用，死亡率，成熟度，繁殖力，鱼具的选择性等，而鱼的体型测量既简单，准确又丰富。在这里，我回顾了基于大小的鱼类种群理论，并将其与经典的基于年龄的理论进行了比较。我证明了基于大小和年龄的人口统计学是人口统计学的等效表示。然而，基于大小的理论是不言而喻的，这导致了更深层次的理论，具有两个优点：与基于年龄的理论相比，预测所需的参数更少，并且该理论直接与生活历史特征相关。与特征的联系使基于大小的理论对于数据贫乏的应用特别有用，并有助于进行进化计算。我将基于年龄和规模的理论用于渔业影响和种群评估，并就单一种群理论的挑战和未来提供一个观点。