caa a22 4500 397550618 CHVBK 20180308164749.0 cr unu---uuuuu 161202e199602 xx s 000 0 eng 10.1006/jmsc.1996.0004 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0004 Which are better, random or systematic acoustic surveys? A simulation using North Sea herring as an example [Elektronische Daten] [E. J. Simmonds, R. J. Fryer] This paper considers the design of acoustic surveys for estimating the mean abundance of spatially correlated populations. We examined how the choice of survey design affects the bias and precision of the sample mean as an estimator of mean abundance. Further, we investigated three different ways of estimating the error variance of the sample mean: the pooled within strata variance and two geostatistical variance estimators based on spherical and exponential models. First, we analysed four surveys to determine the spatial structure of the North Sea herring population. We developed forty different population models based on the observed amplitude and spatial distribution. We generated 1000 realizations of each model, each comprising 4000 potential transect means. Each realization was sub-sampled using eight different sampling strategies. From each realization and sampling strategy, we calculated the sample mean and three estimates of the variance of the sample mean. The simulations show that, for surfaces with local positive correlation, more precise estimates of the surface mean can be obtained using stratified random or systematic sampling than simple random sampling. The best strategy considered here was (a) a systematic survey with a geostatistical variance estimator, when the main objective is to obtain the most precise estimator of abundance, (b) a stratified random survey, with two transects per strata, and a pooled variance estimator, when an important objective of the survey is to obtain a good estimate of the variance of the abundance estimator. © 1996 International council for the Exploration of the Sea Articles nationallicence acoustic surveys nationallicence abundance estimation nationallicence survey strategy nationallicence surveys nationallicence variance estimation nationallicence Simmonds E. J. SOAFD Marine Laboratory, PO Box 101, Victoria Road, Aberdeen, AB9 8DB, U.K aut Fryer R. J. SOAFD Marine Laboratory, PO Box 101, Victoria Road, Aberdeen, AB9 8DB, U.K aut ICES Journal of Marine Science Oxford University Press 53/1(1996-02), 39-50 1054-3139 53:1<39 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0004 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0004 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Simmonds E. J. SOAFD Marine Laboratory, PO Box 101, Victoria Road, Aberdeen, AB9 8DB, U.K aut NATIONALLICENCE 700 1- Fryer R. J. SOAFD Marine Laboratory, PO Box 101, Victoria Road, Aberdeen, AB9 8DB, U.K aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/1(1996-02), 39-50 1054-3139 53:1<39 1996 53 icesjms Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford