An ecological view in time and space: The disappearing sawfishes in the Bay of Bengal, Bangladesh

IF 2.5 3区 环境科学与生态学 Q2 BIODIVERSITY CONSERVATION
Alifa Bintha Haque , Subrata Sarker , Shashowti Chowdhury Riya , Nidhi G. D’Costa , Eurida Liyana , ANM Samiul Huda
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Abstract

Sawfish are Critically Endangered globally, necessitating spatial protection and fisheries management in critical habitats for their preservation. Understanding of such habitats remains limited in the Bay of Bengal, despite the confirmed presence of at least three sawfish species. However, in the past, the species most frequently captured from Bangladesh was the Largetooth Sawfish (Pristis pristis). In this study, using a multidisciplinary approach of ecological modelling of suitable habitats and ground-truthing using fishers' knowledge, habitats for sawfish were identified in Bangladesh’s coastal waters. This was achieved by applying an ethnoecological and georeferenced habitat database to determine suitable habitat for sawfish (mostly Largetooth Sawfish). Landsat imagery and thematic layers were analyzed with ENVI and GIS and developed a series of GIS models to identify and rank suitable grounds. The model outputs were verified with fishers’ local ecological knowledge with an accuracy level of 93%. According to the fishers, catches (from 2019 to 2021) were primarily from the Sundarbans mangrove region, while 60% of fishers reported not observing a sawfish for over two decades in the wild, roughly since the early 2000 s. Most fishers highlighted shallow coastal zones and mangrove-associated rivers as critical habitats for juvenile and adult sawfish. Ecological modeling using a Generalized Additive Model (GAM) revealed that water depth and salinity were the primary drivers of habitat suitability, explaining 19 % and 16 % of the variance, respectively. We found the southwest region, particularly the Sundarbans, as the most potential critical habitat for sawfishes in Bangladesh. We recommend immediate spatial conservation measures and bycatch mitigation amongst others, for the long-term population recovery of sawfish in Bangladesh.
时间和空间的生态观:孟加拉国孟加拉湾消失的锯鳐
锯鳐是全球极度濒危物种,需要在重要栖息地进行空间保护和渔业管理。尽管孟加拉湾已经确认存在至少三种锯鳐,但对这种栖息地的了解仍然有限。然而,在过去,最常从孟加拉国捕获的物种是大齿锯鳐(Pristis Pristis)。在这项研究中,采用多学科方法对适宜栖息地进行生态建模,并利用渔民的知识进行实地调查,在孟加拉国沿海水域确定了锯鳐的栖息地。这是通过应用民族生态学和地理参考栖息地数据库来确定锯鳐(主要是大齿锯鳐)的合适栖息地来实现的。利用ENVI和GIS对Landsat图像和主题层进行分析,开发了一系列GIS模型来识别和排序合适的土地。利用渔民的当地生态知识对模型输出进行了验证,准确率达到93%。根据渔民的说法,渔获量(从2019年到2021年)主要来自孙德尔本斯红树林地区,而60%的渔民报告说,大约从21世纪初开始,已有20多年没有在野外观察到锯鳐。大多数渔民强调,浅海岸带和与红树林相关的河流是幼锯鳐和成年锯鳐的重要栖息地。利用广义加性模型(GAM)建立的生态模型显示,水深和盐度是生境适宜性的主要驱动因素,分别解释了19%和16%的方差。我们发现西南地区,特别是孙德尔本斯,是孟加拉国锯鳐最潜在的关键栖息地。我们建议立即采取空间保护措施和减少副渔获物等,以便孟加拉国锯鳐的长期种群恢复。
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来源期刊
Journal for Nature Conservation
Journal for Nature Conservation 环境科学-生态学
CiteScore
3.70
自引率
5.00%
发文量
151
审稿时长
7.9 weeks
期刊介绍: The Journal for Nature Conservation addresses concepts, methods and techniques for nature conservation. This international and interdisciplinary journal encourages collaboration between scientists and practitioners, including the integration of biodiversity issues with social and economic concepts. Therefore, conceptual, technical and methodological papers, as well as reviews, research papers, and short communications are welcomed from a wide range of disciplines, including theoretical ecology, landscape ecology, restoration ecology, ecological modelling, and others, provided that there is a clear connection and immediate relevance to nature conservation. Manuscripts without any immediate conservation context, such as inventories, distribution modelling, genetic studies, animal behaviour, plant physiology, will not be considered for this journal; though such data may be useful for conservationists and managers in the future, this is outside of the current scope of the journal.
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