caa a22 4500 397551525 CHVBK 20180308164751.0 cr unu---uuuuu 161202e199604 xx s 000 0 eng 10.1006/jmsc.1996.0060 doi (NATIONALLICENCE)oxford-10.1006/jmsc.1996.0060 Analysis of Spanish acoustic surveys for sardine, 1991-1993: abundance estimates and inter-annual variability [Elektronische Daten] [C. Porteiro, P. Carrera, J. Miquel] Systematic acoustic surveys to estimate the Spanish fraction of the Atlantic sardine stock were begun in 1983. Since 1991, with the use of the new SIMRAD EK500 echo-sounder-echo-integrator, the area covered has been extended to the 1000 m depth contour to observe the complete distribution of the main pelagic species. The last three surveys, from spring 1991 to spring 1993, had a range of 20-1000 m depth. They were first analysed using traditional methodology, which does not give any estimation of the variance. The data were therefore analysed using geostatistical techniques and the resulting estimates of relative abundance were compared. Sardine showed high variability between years and zones both in distribution and density, expressed as number of fish per square nautical mile. The two methods of analysis gave different biomass estimates by zone, especially in 1993. Variograms computed over areas of fish presence did not show, in general, a clear spatial structure and sills were reached at 3 nmi of range. The precision of these variograms was low, ranging from 23-40%, expressed as relative standard error. In order to improve precision it is necessary to increase sampling intensity and change the survey grid. For sardine, a systematic parallel survey design with a random start and 6 nmi between transects would be more appropriate. © 1996 International Council for the Exploration of the Sea Regular Articles nationallicence acoustic survey nationallicence geostatistics nationallicence Iberian Peninsula nationallicence Sardina pilchardus nationallicence spatial distribution nationallicence Porteiro C. Instituto Español de Oceanografía Centro Oceanográfico de Vigo, Apartado 1552, 36280 Vigo, Spain aut Carrera P. Instituto Español de Oceanografía Centro Oceanográfico de A Coruña, Apartado 130, 15080 A Coruña, Spain aut Miquel J. Instituto Español de Oceanografía Centro Oceanográfico de Baleares, Apartado 291, 07080 Palma de Mallorca, Spain aut ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 429-433 1054-3139 53:2<429 1996 53 icesjms https://doi.org/10.1006/jmsc.1996.0060 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1006/jmsc.1996.0060 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Porteiro C. Instituto Español de Oceanografía Centro Oceanográfico de Vigo, Apartado 1552, 36280 Vigo, Spain aut NATIONALLICENCE 700 1- Carrera P. Instituto Español de Oceanografía Centro Oceanográfico de A Coruña, Apartado 130, 15080 A Coruña, Spain aut NATIONALLICENCE 700 1- Miquel J. Instituto Español de Oceanografía Centro Oceanográfico de Baleares, Apartado 291, 07080 Palma de Mallorca, Spain aut NATIONALLICENCE 773 0- ICES Journal of Marine Science Oxford University Press 53/2(1996-04), 429-433 1054-3139 53:2<429 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