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首页> 外文期刊>Fisheries Research >Hydroacoustic separation of rainbow smelt (Osmerus mordax) age groupsin Lake Champlain
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Hydroacoustic separation of rainbow smelt (Osmerus mordax) age groupsin Lake Champlain

机译：尚普兰湖彩虹熔岩（Osmerus mordax）年龄组的水声分离

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Separate assessment of young-of-year (YOY) and yearling-and-older (YAO) fish is desirable from both ecological and management perspectives. Acoustic assessments provide information on fish population size structure in the target strength (TS) distribution, but interpretation of TS distributions must be done carefully, as single age groups can produce multiple TS modes. We assessed the ability of in situ TS distributions to identify Lake Champlain rainbow smelt (Osmerus mordax) age groups in June, July, and September of 2001 using mobile and stationary surveys, knowledge of vertical distribution preferences, and predicted TS from trawl catches. YAO rainbow smelt (93-179 mm total length) had wide TS distributions between -60 and -35 dB in all 3 months with two modes at approximately -50 and -40 dB. Most stationary survey single-fish tracks attributed to YAO had targets in both TS modes and a wide TS range often over 15 dB. Between June and September, YOY rainbow smelt TS increased, but single-fish tracks were unimodal, and the TS range was smaller (6 dB). Overlap in TS attributed to YOY and YAO increased from no overlap in June (YOY TS -76 to -61 dB, 15-25 mm) to moderate overlap in July (-76 to -50 dB, 25-63 mm) to considerable overlap in September (-68 to -45 dB, 33-80 mm). In June and July, the TS distribution changed abruptly at the thermocline, indicating almost complete separation of the two groups. A more gradual TS transition was evident in September, indicating substantial overlap between YOY and YAO. Separate estimates can be obtained in September by decomposing TS overlap into components attributed to YOY and YAO rainbow smelt. However, this decomposition introduces additional uncertainty and an assessment in July or possibly August is preferable to obtain separate abundance estimates of YOY and YAO.
机译：从生态学和管理学的角度出发，最好分别对年幼鱼和一岁以上幼鱼进行评估。声学评估可提供有关目标强度（TS）分布中鱼类种群大小结构的信息，但是必须谨慎进行TS分布的解释，因为单个年龄组会产生多种TS模式。我们使用移动和静态调查，垂直分布偏好知识以及从拖网捕获物中预测的TS，评估了原位TS分布识别2001年6月，7月和9月Champlain湖彩虹味（Osmerus mordax）年龄组的能力。 YAO彩虹熔炼（总长度93-179 mm）在所有三个月中的TS分布在-60和-35 dB之间，并在大约-50和-40 dB处出现两种模式。大部分归因于YAO的固定单鱼调查航迹在TS模式下都有目标，而且TS范围较宽，通常超过15 dB。在6月和9月之间，YOY彩虹熔炼的TS有所增加，但单鱼径为单峰，且TS范围较小（6 dB）。归因于YOY和YAO的TS重叠从6月的无重叠（YOY TS -76到-61 dB，15-25 mm）增加到7月的中等重叠（-76到-50 dB，25-63 mm）至相当的重叠9月（-68至-45 dB，33-80 mm）。在6月和7月，温床的TS分布突然改变，表明两组几乎完全分开。 9月份的TS过渡较为平缓，这表明YOY和YAO之间存在大量重叠。通过将TS重叠分解为YOY和YAO彩虹熔炼的成分，可以在9月获得单独的估算值。但是，这种分解会带来额外的不确定性，因此最好在7月或8月进行评估，以获得单独的YOY和YAO丰度估计。

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