Comparison of geostatistical and random sample survey analyses of Antarctic krill acoustic data
نویسنده
چکیده
Data from the acoustic surveys of MV SA ‘‘Agulhas’’ and FRV ‘‘Walther Herwig’’, and the 1981 RRS ‘‘John Biscoe’’ South Georgia acoustic survey were analysed by geostatistical methods. Estimates of mean density (g m) of krill and their variances are compared with published results from statistical analyses based on random sampling theory. A further high-resolution geostatistical analysis of the MV SA ‘‘Agulhas’’ (ping-by-ping) data set of the density of each individual aggregation is also presented. These analyses illustrate the problems of applying geostatistical methods to data from highly aggregated species which can show marked skewness in their histogram of density.
منابع مشابه
The use of acoustic sampling to estimate the dispersion and abundance of euphausiids, with an emphasis on Antarctic krill, Euphausia superba
Acoustic sampling has been used to investigate the ecology of Antarctic krill (Euphausia superba) and to provide information on dispersion and abundance necessary to manage their harvest. Population estimates based on multi-ship acoustic surveys have been used to set catch limits. More localized acoustic surveys have been conducted to study the response of landbreeding krill predators to local ...
متن کاملUse of moored acoustic instruments to measure short-term variability in abundance of Antarctic krill
Upward-looking acoustic Doppler current profilers (ADCPs) (300 kHz) and echosounders (125 kHz) were deployed on moorings at South Georgia to measure abundance of Antarctic krill continuously over several months. Echoes from krill were identified using the theoretical difference in echo intensity at 300 and 125 kHz and scaled to krill density using target strengths appropriate for krill in the r...
متن کاملA Hybrid Data Clustering Algorithm Using Modified Krill Herd Algorithm and K-MEANS
Data clustering is the process of partitioning a set of data objects into meaning clusters or groups. Due to the vast usage of clustering algorithms in many fields, a lot of research is still going on to find the best and efficient clustering algorithm. K-means is simple and easy to implement, but it suffers from initialization of cluster center and hence trapped in local optimum. In this paper...
متن کاملPalmer LTER: Grazing by the antarctic krill Euphausia superba on Nitschia sp. and Phaeocystis sp. monocultures
Figure 3. Cumulative frequency distribution of the mean krill bio mass (g nr2) of 1-km subsamples for the fast (solid line) and slow (dashed line) surveys. Cram, D.L., J.J. Agenbag, I. Hampton, and A.A. Robertson. 1979. SAS Protea Cruise, 1978: The general results of the acoustics and remote sensing study, with recommendations for estimating the abundance of krill {Euphausia superba Dana). Sout...
متن کاملRelative Changes in Krill Abundance Inferred from Antarctic Fur Seal
Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is...
متن کامل