Volume backscattering strength samples and echograms (38 kHz) associated to small pelagic fish schools in the Gulf of California, Mexico

Sv (dB re m-1) data samples taken from fish schools and their surrounding echoes in echograms associated to small pelagic fish in the Midriff Islands Region of the Gulf of California, Mexico. Acoustic data was acquired using a SIMRAD EK60 scientific echosounder with a 38 kHz split-beam transducer during May, 2013. Two files are provided, the data itself (Sv samples and three echograms) and the R-code needed to recreate figures and analysis in López-Serrano et al. 2017 (https://doi.org/10.1051/alr/2017048). File description: - LopezSerrano_et_al_code.R Ascii file (encoding UTF-8) with the R-code for re-creating the figures and analysis in the paper. - LopezSerrano_et_al_data.RData Binary RData file with all the data used in the paper. Once loaded in R, it contains 4 objects: A table (data frame) and three echograms. The first table contains nine columns: id, x, y, pingNumber, pingTime, depth, Sv038, trawlNo, category The echograms (eco.L04, eco.L14, eco.L17) are objects of class “echogram”, which are described below according to the R package echogram: An object of class “echogram” (a list) with components: depth : a vector of mean sample depth (in m) of length p. Sv : a p by k matrix of sampled values, currently the mean volume backscattering strength (Sv, in dB). pings : a k by four data frame with ping time, detected bottom depth, vessel speed and cummulated traveled distance.

Sv（单位：dB re m⁻¹）数据样本取自墨西哥加利福尼亚湾Midriff群岛区域小型中上层鱼类相关回声图（echograms）中的鱼群及其周围回声。

声学数据于2013年5月使用配备38 kHz分裂波束换能器（split-beam transducer）的SIMRAD EK60科学回声测深仪采集。

提供两个文件：数据本身（含Sv样本及三个回声图），以及重现López-Serrano等人2017年论文（https://doi.org/10.1051/alr/2017048）中图表与分析所需的R代码。

文件描述：
- LopezSerrano_et_al_code.R：ASCII文件（编码UTF-8），包含用于重现论文中图表与分析的R代码。
- LopezSerrano_et_al_data.RData：二进制RData文件，包含论文中使用的所有数据。在R中加载后，它包含4个对象：一个数据框（data frame）和三个回声图。第一个表格包含九列：id、x、y、pingNumber、pingTime、depth、Sv038、trawlNo、category。回声图（eco.L04、eco.L14、eco.L17）为“echogram”类对象，根据R包echogram的描述，该类对象（列表形式）包含以下组件：
depth：长度为p的平均样本深度向量（单位：m）；
Sv：p×k的采样值矩阵，当前为平均体积反向散射强度（mean volume backscattering strength，单位：dB）；
pings：k×4的数据框，包含ping时间、探测海底深度、船速及累计行驶距离。