scholarly journals Recruitment of Antarctic krill Euphausia superba in the South Georgia region: adult fecundity and the fate of larvae

2007 ◽  
Vol 331 ◽  
pp. 161-179 ◽  
Author(s):  
GA Tarling ◽  
J Cuzin-Roudy ◽  
SE Thorpe ◽  
RS Shreeve ◽  
P Ward ◽  
...  
Keyword(s):  
Antarctic Krill ◽  
Euphausia Superba ◽  
The South ◽  
South Georgia ◽  
Antarctic Krill Euphausia Superba

scholarly journals Clarifying trends in the density of Antarctic krill Euphausia superba Dana, 1850 in the South Atlantic. A response to Hill et al

2019 ◽  
Vol 39 (3) ◽  
pp. 323-327 ◽  
Author(s):  
Martin James Cox ◽  
Steven Candy ◽  
William K De la Mare ◽  
Stephen Nicol ◽  
So Kawaguchi ◽  
...  
Keyword(s):  
Antarctic Krill ◽  
Euphausia Superba ◽  
South Atlantic ◽  
The South ◽  
Antarctic Krill Euphausia Superba

Stable isotopes identify an ontogenetic niche expansion in Antarctic krill (Euphausia superba) from the South Shetland Islands, Antarctica

2013 ◽  
Vol 160 (6) ◽  
pp. 1311-1323 ◽  
Author(s):  
Michael J. Polito ◽  
Christian S. Reiss ◽  
Wayne Z. Trivelpiece ◽  
William P. Patterson ◽  
Steven D. Emslie
Keyword(s):  
Stable Isotopes ◽  
Antarctic Krill ◽  
Euphausia Superba ◽  
South Shetland Islands ◽  
The South ◽  
Niche Expansion ◽  
Shetland Islands ◽  
Ontogenetic Niche ◽  
Antarctic Krill Euphausia Superba

scholarly journals Spatial and temporal variability in the structure of aggregations of Antarctic krill (Euphausia superba) around South Georgia, 1997–1999

2011 ◽  
Vol 68 (3) ◽  
pp. 489-498 ◽  
Author(s):  
Martin J. Cox ◽  
Jonathan L. Watkins ◽  
Keith Reid ◽  
Andrew S. Brierley
Keyword(s):  
Temporal Variability ◽  
Antarctic Krill ◽  
Marine Ecosystem ◽  
Euphausia Superba ◽  
Spatial And Temporal Variability ◽  
Dual Frequency ◽  
South Georgia ◽  
Estimation System ◽  
Antarctic Krill Euphausia Superba

Abstract Cox, M. J., Watkins, J. L., Reid, K., and Brierley, A. S. 2011. Spatial and temporal variability in the structure of aggregations of Antarctic krill (Euphausia superba) around South Georgia, 1997–1999. – ICES Journal of Marine Science, 68: . Antarctic krill are important in the South Georgia (54°S 35°W) marine ecosystem. They form aggregations that vary widely in packing density (<1 to 1000 s of individuals m−3), length (tens to thousands of metres), and height (tens of metres). Acoustic surveys are often used to estimate krill biomass and provide data that give insight into aggregation structure. Using dual-frequency (38 and 120 kHz) acoustic data collected during six surveys conducted around South Georgia during the 1997, 1998, and 1999 austral summers, we isolated 2990 aggregations by applying the Shoal Analysis and Patch Estimation System algorithm in Echoview and a krill-length-dependent acoustic identifier (ΔSv120–38). Multivariate cluster (partition) analysis was applied to metrics from each of the aggregations, resulting in three aggregation types with an overall proportional split of 0.28:0.28:0.44. Types 1 and 3 had low mean densities (<2 g m−3), whereas Type 2 had a mean density of 94 g m−3. Intersurvey differences were found between the effort-corrected numbers of aggregation types (p = 2.5e−6), and between on- and off-continental shelf areas (p = 1.5e−7), with a greater number of Type 2 aggregations being found on-shelf. The findings suggest intersurvey variation in krill catchability, with krill being more likely to be caught on-shelf.

scholarly journals Interannual variability in Antarctic krill (Euphausia superba) density at South Georgia, Southern Ocean: 1997–2013

2014 ◽  
Vol 71 (9) ◽  
pp. 2578-2588 ◽  
Author(s):  
Sophie Fielding ◽  
Jonathan L. Watkins ◽  
Philip N. Trathan ◽  
Peter Enderlein ◽  
Claire M. Waluda ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Interannual Variability ◽  
Antarctic Krill ◽  
Southern Oscillation ◽  
Euphausia Superba ◽  
Target Strength ◽  
South Georgia ◽  
Key Species ◽  
The Mean ◽  
Antarctic Krill Euphausia Superba

Abstract Antarctic krill (Euphausia superba) are a key species in Southern Ocean ecosystems, maintaining very large numbers of predators, and fluctuations in their abundance can affect the overall structure and functioning of the ecosystems. The interannual variability in the abundance and biomass of krill was examined using a 17-year time-series of acoustic observations undertaken in the Western Core Box (WCB) survey area to the northwest of South Georgia, Southern Ocean. Krill targets were identified in acoustic data using a multifrequency identification window and converted to krill density using the Stochastic Distorted-Wave Born Approximation target strength model. Krill density ranged over several orders of magnitude (0–10 000 g m−2) and its distribution was highly skewed with many zero observations. Within each survey, the mean krill density was significantly correlated with the top 7% of the maximum krill densities observed. Hence, only the densest krill swarms detected in any one year drove the mean krill density estimates for the WCB in that year. WCB krill density (µ, mean density for the area) showed several years (1997/1998, 2001–2003, 2005–2007) of high values (µ > 30 g m−2) interspersed with years (1999/2000, 2004, 2009/2010) of low density (µ < 30 g m−2). This pattern showed three different periods, with fluctuations every 4–5 years. Cross correlation analyses of variability in krill density with current and lagged indices of ocean (sea surface temperature, SST and El Niño/Southern Oscillation) and atmospheric variability (Southern Annular Mode) found the highest correlation between krill density and winter SST (August SST) from the preceding year. A quadratic regression (r2 = 0.42, p < 0.05) provides a potentially valuable index for forecasting change in this ecosystem.

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