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首页> 外文期刊>Fisheries Research >Incorporating fish orientation into target strength-total length equations: Horizontal-Aspect target-Strength equations for gizzard shad Dorosoma cepedianum
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Incorporating fish orientation into target strength-total length equations: Horizontal-Aspect target-Strength equations for gizzard shad Dorosoma cepedianum

机译：将鱼取向纳入目标强度 - 总长度方程：Gizzard Shad Dorosoma谱中的横向目标 - 强度方程

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摘要

Horizontally-oriented echosounders have become more common for sampling pelagic prey species in shallow waterbodies (e.g. 20 m) or nearshore portions of deeper water bodies, where vertical beaming can be ineffective. To properly sample fishes with horizontally-oriented echosounders, a target-strength (TS; dB re 1 m(2))-to-total-length (TL; mm) relationship must be developed to acquire reliable density data. However, when sampling with horizontal beaming, measured TS can vary greatly according to fish orientation (lateral versus head-on). Currently, a TS-TL equation that is based on TS data from individual fish measured at all orientations is used to convert between TL and measured TS. However, an orientation-based equation (equation that incorporates target orientation information when converting TS to TL) could increase the accuracy of size estimates from direct TS measurements. Target strength measurements were collected from euthanized Gizzard Shad Dorosoma cepedianum, in a tank, at orientations from 0 to 180 degrees (0 degrees and 180 degrees being perpendicular to acoustic beam and 90 degrees parallel with head facing the transducer) in 5 degrees increments. We derived orientation-based and non-orientation-based TS-TL equations for Gizzard Shad. Eight orientation-based equations were compared with a catenary (U-Shape) function best representing the change in TS for different fish orientations (conditional R-2 = 0.71 and marginal R-2 = 0.67). Our orientation-based equation can be used to acquire more accurate Gizzard Shad biomass estimates when orientation information is available. We found significant errors occur when using an average-orientation TS-TL equation when fish do not have random orientation, so orientation-based equations should be used when possible. We also compared density estimates from previously published, non-orientation-based TSMean equations (TS-TL equation derived from mean TS of all target orientations) to determine if equation choice significantly affected density estimates from fish aggregations. Equation choice had a significant effect on the resulting density estimates from individual schools (P 0.01), indicating species-specific equations provide greater accuracy.
机译：以水平定向的回声驱动器在浅水层（例如＆LT 192米）或深层水体的近岸部分中的采样，垂直光束可能无效。为了用水平取向的回声驱动器进行正确的样本，必须开发目标强度（TS; DB RE 1 M（2）） - 全长（TL; mm）关系以获取可靠的密度数据。然而，当使用水平射束采样时，测量的Ts可以根据鱼取向（横向与头部）而变化。目前，基于在所有方向上测量的各个鱼的TS数据的TS-TL等式用于在TL和测量TS之间进行转换。然而，基于方向的等式（在转换TS到T1时结合目标方向信息的等式）可以提高直接TS测量的大小估计的精度。从安乐死的Gizzard Shad Dorosoma Cepedianum，在罐中，以0到180度（0度和180度垂直于声学光束的90度，与面向换能器平行的90度平行）的方向收集目标强度测量。我们为GIZHARD SHAG获得了基于基于的基于非定向的TS-TL方程。将八个基于方程式的方程与凸起的（U形）函数进行比较，最佳代表不同鱼取向的TS变化（条件R-2 = 0.71和边缘R-2 = 0.67）。当方向信息可用时，我们基于定向的方程可用于获取更准确的Gizzard BioMass估计。当鱼没有随机取向时，我们发现在使用平均方向TS-TL方程时发生了重大错误，因此应在可能的情况下使用基于方向的方程。我们还比较了先前公布的基于非定向的TSMean方程（来自所有目标方向的平均值的TS-T1方程的TS-TL方程）的密度估计，以确定等式选择是否显着影响了鱼聚集的密度估计。等式选择对来自个别学校的所得密度估计（P <0.01）产生显着影响，指示物种特定方程提供更大的准确性。

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