Abstract Understanding the dynamics of juvenile fish populations is a key component to understanding variation in adult populations, however, juvenile fish are frequently found in a variety of structurally complex habitats which are often not easily sampled. The use of baited (BRUV) and unbaited (RUV) remote underwater stereo-video to study juvenile fish populations is uncommon and thus far, no study has directly compared the efficacy of these two methods solely for juvenile fish assemblages. The macro-tidal Kimberley region in the north-west of Australia is challenging to sample using diver-based methods due to the strong currents and prevalence of saltwater crocodiles (Crocodylus porosus). We sampled 60 Stereo-RUVs and 60 Stereo-BRUVs across four shallow-water (1-6 m) benthic habitats: coral, mangrove, macroalgae, and seagrass, to contrast the effect of the presence or absence of bait, deployment period, in-water visibility and tidally driven water speed on estimates of relative total abundance, species richness, and composition of the juvenile fish assemblage. No difference was detected in the ability of stereo-BRUV or stereo-RUV to quantify the relative total abundance, species richness, or assemblage composition of juvenile fish. We also found little effect of in-water visibility or tidally driven water speed, likely as a result of stratifying our sampling to slack water periods. We found that a deployment period of 10 min for Stereo-BRUVs and 15 min for Stereo-RUVs was optimum for sampling the juvenile fish assemblage across all four contrasting habitats. Since no statistical significance was observed between 10 and 15 min, we recommend that Stereo-RUVs deployed for 15 min during tidal slack water conditions are an optimum way to provide consistent results for comparisons of juvenile fish assemblage metrics across the benthic habitats studied within this region. The controlled video methodologies described here provided an opportunity to access un-sampled juvenile fish habitats and assemblages where traditional diver-based methodologies are impossible. Applying these methods broadly can help to improve our understanding of the status of juvenile fish and infer the reproductive success and viability of their populations across a range of habitat and environments.

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在具有挑战性的环境中研究幼鱼种群的远程视频方法

摘要 了解幼鱼种群的动态是了解成鱼种群变化的关键组成部分，然而，幼鱼经常在各种结构复杂的栖息地中发现，这些栖息地通常不容易采样。使用诱饵 (BRUV) 和无诱饵 (RUV) 远程水下立体视频来研究幼鱼种群并不常见，到目前为止，还没有研究直接比较这两种方法仅对幼鱼组合的功效。由于强流和咸水鳄鱼（Crocodylus porosus）的流行，澳大利亚西北部的大潮金伯利地区很难使用基于潜水员的方法进行采样。我们在四个浅水 (1-6 m) 底栖栖息地采样了 60 个立体 RUV 和 60 个立体 BRUV：珊瑚、红树林、大型藻类和海草，对比是否存在诱饵、部署时间、水中能见度和潮汐驱动的水速对相对总丰度、物种丰富度和幼鱼组合组成的估计的影响。立体 BRUV 或立体 RUV 量化幼鱼的相对总丰度、物种丰富度或组合组成的能力没有检测到差异。我们还发现水中能见度或潮汐驱动的水速几乎没有影响，这可能是将我们的采样分层到枯水期的结果。我们发现 Stereo-BRUV 的部署时间为 10 分钟，Stereo-RUV 的部署时间为 15 分钟，最适合在所有四个对比栖息地对幼鱼组合进行采样。由于在 10 到 15 分钟之间没有观察到统计显着性，我们建议在潮汐滞水条件下部署 15 分钟的立体 RUV 是为该区域内研究的底栖栖息地的幼鱼组合指标比较提供一致结果的最佳方式。此处描述的受控视频方法提供了访问未采样的幼鱼栖息地和组合的机会，在这些地方，传统的基于潜水员的方法是不可能的。广泛应用这些方法有助于提高我们对幼鱼状况的了解，并推断其种群在一系列栖息地和环境中的繁殖成功率和生存能力。此处描述的受控视频方法提供了访问未采样的幼鱼栖息地和组合的机会，在这些地方，传统的基于潜水员的方法是不可能的。广泛应用这些方法有助于提高我们对幼鱼状况的了解，并推断其种群在一系列栖息地和环境中的繁殖成功率和生存能力。此处描述的受控视频方法提供了访问未采样的幼鱼栖息地和组合的机会，在这些地方，传统的基于潜水员的方法是不可能的。广泛应用这些方法有助于提高我们对幼鱼状况的了解，并推断其种群在一系列栖息地和环境中的繁殖成功率和生存能力。