TY - JOUR
T1 - Evaluating the uncertainty of abundance estimates from acoustic surveys using geostatistical simulations
AU - Woillez, Mathieu
AU - Rivoirard, Jacques
AU - Fernandes, Paul G.
N1 - Funding Information:
This study was conducted with the financial support of the European Union (project FISBOAT, 2004–2007, Fisheries Independent Survey-based Operational Assessment Tools, Contract 502572). The analysis was conducted using R routines developed by Didier Renard, Mathieu Woillez, Nicolas Bez, and Jacques Rivoirard (Mines-ParisTech, Centre de Géostatistique, France).
PY - 2009/7
Y1 - 2009/7
N2 - Geostatistical simulations, which can reproduce the spatial variability of a variable, are particularly helpful in estimating the uncertainty associated with the combination of different sources of variability. Acoustic surveys offer an example of such complex situations, where different data (e.g. acoustic backscatter, fish length, and fish age) must be combined to estimate abundance and its associated uncertainty. In this paper, the uncertainty of Scottish herring acoustic-survey estimates is investigated using these techniques. A specific multivariate, geostatistical model is used to describe the structural relationships, which includes highly skewed distributions of the acoustic-backscatter data and incorporates relationships between depth, mean length, and proportions-at-age. Conditional simulations, i.e. geostatistical simulations that honour the data values known at the data points, are used to generate multiple realizations of acoustic backscatter, mean length, and proportions-at-age. These are combined to produce multiple realizations of herring density over the sampled domain. Multiple realizations of total abundance and abundance-at-age are then provided. The uncertainty is assessed using basic statistics to track the significant variations of these values over the period 1989-2005. Higher coefficients of variation (CVs) are found on average for extreme ages (ages 1, 2i, 8, and 9+); otherwise, CVs are mostly around 12% for abundance-atage and around 10% for total abundance.
AB - Geostatistical simulations, which can reproduce the spatial variability of a variable, are particularly helpful in estimating the uncertainty associated with the combination of different sources of variability. Acoustic surveys offer an example of such complex situations, where different data (e.g. acoustic backscatter, fish length, and fish age) must be combined to estimate abundance and its associated uncertainty. In this paper, the uncertainty of Scottish herring acoustic-survey estimates is investigated using these techniques. A specific multivariate, geostatistical model is used to describe the structural relationships, which includes highly skewed distributions of the acoustic-backscatter data and incorporates relationships between depth, mean length, and proportions-at-age. Conditional simulations, i.e. geostatistical simulations that honour the data values known at the data points, are used to generate multiple realizations of acoustic backscatter, mean length, and proportions-at-age. These are combined to produce multiple realizations of herring density over the sampled domain. Multiple realizations of total abundance and abundance-at-age are then provided. The uncertainty is assessed using basic statistics to track the significant variations of these values over the period 1989-2005. Higher coefficients of variation (CVs) are found on average for extreme ages (ages 1, 2i, 8, and 9+); otherwise, CVs are mostly around 12% for abundance-atage and around 10% for total abundance.
KW - Acoustic survey
KW - Conditional simulations
KW - Geostatistics
KW - Scottish herring
UR - http://www.scopus.com/inward/record.url?scp=80054097080&partnerID=8YFLogxK
U2 - 10.1093/icesjms/fsp137
DO - 10.1093/icesjms/fsp137
M3 - Article
AN - SCOPUS:80054097080
SN - 1054-3139
VL - 66
SP - 1377
EP - 1383
JO - ICES Journal of Marine Science
JF - ICES Journal of Marine Science
IS - 6
ER -