Inland rift valley lake systems have been sustaining humanity for a long time. Only recently have commercial fisheries entered these systems and for Lake Malawi, this occurred in the mid-1970s upon successful experimental trawl fishing. Lake Malawi with the highest diversity of freshwater fishes in the world has had fisheries for centuries. Previous assessment of the impact of commercial trawl fisheries revealed significant changes in stock composition and overall biomass. The study evaluates the state of fisheries resources using novel techniques developed using integrated assessment methods amenable to data poor fisheries. Data from biomass assessment surveys and landed catch from 2016 to 2019 were examined to determine the status of selected fish stocks over time. Stock Synthesis for Data Limited tools in R environment were used to run the models. The Surplus Production Models and Statistical catch-at-age models that were used to examine alternative hypotheses on life history parameters on the key stocks exploited primarily by the commercial trawl fishery and evaluate long-term trends on these populations. The study results revealed that Mcheni (Rhamphochromis spp.), Ndunduma (Diplotaxodon limnothrissa) and Utaka (Copadichromis virginalis) stocks are within the sustainable limits, while Chambo (Oreochromis karongae), Chisawasawa (Lethrinops gossei), Mlamba (Bathyclarias nyasensis) and Kampango (Bagrus meridionalis) appear to be overfished in recent years, though Kampango may have recovered recently. Given, the large uncertainties with productivity of most tropical fishes with climate change, as well as large uncertainties due to inaccurate and untimely data submissions, it is recommended that a systematic monitoring and evaluation program, like the one being conducted in Lake Malawi should be developed for other inland lake systems. If stocks are facing overfishing by both the small-scale and commercial trawl fisheries, limits to overall catch and size should be implemented possibly through output controls such that the fisheries remain sustainable for the long term.

中文翻译：

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对东非内陆湖马拉维湖鱼类种群的现状进行建模

内陆裂谷湖泊系统长期以来一直维持着人类的生存。直到最近，商业渔业才进入这些系统，对于马拉维湖来说，这发生在 20 世纪 70 年代中期，拖网捕鱼实验取得成功。马拉维湖拥有世界上淡水鱼类最丰富的多样性，几个世纪以来一直从事渔业。先前对商业拖网渔业影响的评估显示种群组成和总体生物量发生了显着变化。该研究利用适合数据匮乏的渔业的综合评估方法开发的新技术评估渔业资源状况。对 2016 年至 2019 年生物量评估调查和上岸渔获量的数据进行了检查，以确定选定鱼类种群随时间变化的状况。 R 环境中的 Stock Synthesis for Data Limited 工具用于运行模型。剩余生产模型和统计捕捞年龄模型用于检验主要由商业拖网渔业开发的关键种群的生活史参数的替代假设，并评估这些种群的长期趋势。研究结果显示，Mcheni (Rhamphochromis spp.)、Ndunduma (Diplotaxodon limnothrissa) 和 Utaka (Copadichromis virginalis) 种群处于可持续限度内，而 Chambo (Oreochromis karongae)、Chisawasawa (Lethrinops gossei)、Mlamba (Bathyclarias nyasensis) 和 Kampango近年来，鲇鱼（Bagrus meridionalis）似乎遭到过度捕捞，但坎潘戈最近可能已经恢复。鉴于大多数热带鱼类的生产力随气候变化而存在很大的不确定性，以及由于数据提交不准确和不及时而带来的很大的不确定性，建议制定一项系统性的监测和评估计划，例如在马拉维湖进行的监测和评估计划对于其他内陆湖泊系统。如果种群面临小规模和商业拖网渔业的过度捕捞，则应尽可能通过产量控制来限制总体捕捞量和规模，以使渔业保持长期可持续发展。