Output of population growth and fishing model for Longspined sea urchins (Centrostephanus rodgersii)

This study created a size-structured stock assessment model to examine the population dynamics and fishing impacts on the long-spined sea urchin (Centrostephanus rodgersii) on the east coast of Tasmania, Australia. The model tracks urchin abundance and growth through size classes over time, using a transition matrix to determine how individuals grow each year, for nine (9) East Coast Tasmanian regions described by Ling and Keane (2018). It begins in 1960 with no population, reflecting the species' first recorded presence in Tasmania in 1978. The model runs until 2160, but the focus of the paper and results is for management options in the next 5 to 10 years, plus retrospective examination for the past 15 years since commercial fishing began.The model generates data through the model testing and fitting process. Output files are defined by three 'classes' (biomean, fitsum, nevermean), with each class producing results for the nine different geographic regions.(1) 'biomean' is predicted urchin density (kg/m2) for each region;(2) 'fitsum' is the Rstan-produced model fit for each region, where the model provides a fit of an equation for recruitment over time based on a sigmoidal increase function;(3) 'nevermean' is the predicted/projected urchin density if no commercial fishing ever occurred for each region. The modelling process is fully described in the associated journal article (in final preparation). A description of files is provided in the 'Lineage' section of this record.

本研究构建了基于体型结构的渔业资源评估模型，旨在探究澳大利亚塔斯马尼亚东海岸长棘海胆（Centrostephanus rodgersii）的种群动态及其受捕捞活动的影响。该模型通过时间序列的体型分级追踪海胆的丰度与生长过程，依托转移矩阵明确个体每年的生长转换规律，涵盖Ling与Keane（2018）所界定的9个塔斯马尼亚东海岸海域。模型以1960年种群数量为零作为初始状态，契合该物种1978年首次在塔斯马尼亚被记录的历史背景。模型模拟时段截至2160年，但本研究的核心聚焦于未来5至10年的管理方案，同时回溯分析商业捕捞开展以来近15年的种群变化情况。本数据集通过模型校验与拟合流程生成，输出文件分为三类（biomean、fitsum、nevermean），每类均针对9个地理区域生成对应结果：(1) biomean：各区域海胆的预测密度（kg/m²）；(2) fitsum：由Rstan生成的各区域模型拟合结果，该拟合基于S型增长函数构建了种群补充量随时间变化的方程；(3) nevermean：各区域未发生任何商业捕捞情景下的海胆预测/预估密度。本建模流程的详细说明已见于即将见刊的相关期刊论文，数据集的文件结构说明详见本记录的"谱系（Lineage）"章节。