Experimental studies into growth and ageing of krill 1993-2003

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Metadata record for data from ASAC Project 2337 See the link below for public details on this project.\n \n---- Public Summary from Project ----\nThe experimental krill research program is focused on obtaining life history information of use in managing the krill fishery - the largest Antarctic fishery. In particular, the program will concentrate on studies into schooling, growth and ageing of krill.\n \nFrom the abstracts of some of the referenced papers:\n \nNucleic acid contents of tissue were determined from field-caught Antarctic krill to determine whether they could be used as an alternative estimator of individual growth rates which can currently only be obtained by labour intensive on-board incubations. Krill from contrasting growth regimes from early and late summer exhibited differences in RNA-based indices. There was a significant correlation between the independently measured individual growth rates and the RNA-based indices. There was a significant correlation between the independently measured individual growth rates and the RNA:DNA ratio and also the RNA concentration of krill tissue, although the strength of the relationship was only modest. DNA concentration, on average, was relatively constant, irrespective of the growth rates. The moult stage did not appear to have a significant effect on the nucleic acid contents of tissue. Overall, the amount of both nucleic acids varied considerably between individuals. Nucleic acid-based indicators may provide information concerning the recent growth and nutritional status of krill and further experimentation under controlled conditions is warranted. The are, however, reasonably costly and time-consuming measurements.\n \nGrowth rates of Antarctic krill Euphausia superba Dana in the Indian Ocean sector of the Southern Ocean were measured in 4 summers. Growth rate was measured using an 'instantaneous growth rate' technique which involved measuring the mean change in length if the uropods at moulting. In the first 4 days following collection mean growth rates ranged from 0.35 to 7.34% per moult in adults and 2.42 to 9.05% in juveniles. Mean growth rates of adult and juvenile krill differed between areas and between the different years of the investigation. When food was restricted under experimental conditions, individual krill began to shrink immediately and mean population growth rates decreased gradually, becoming negative after as little as 7 days. Populations of krill which exhibited initial growth rates began to shrink later than those which had initially been growing more slowly.\n \nData were collected on growth rates of krill.\n \nThese data were collected as part of ASAC projects 34, 1074, 2220 and 2337.\n \nASAC_34 - Ecophysiology of Antarctic Krill 'Euphausia superba'\nASAC_1074 - Seasonal growth in krill\nASAC_2220 - Collection of live Antarctic krill\nASAC_2337 - Experimental studies into growth and ageing of krill\n\nThe fields in this dataset are:\n\nField season (eg FS9596 = Field Season 1995-1996) Area (eg Indian Ocean) Cruise Month Date Latitude Longitude Total Number of Krill Dead Krill Moulted Krill Experiment ID Station ID Sample ID Sex Growth (IGR%) (% growth at time of moulting) Uropod Size (mm) Days after capture (when moulted) Standard length

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