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VIII. CURRENT INFORMATION AND FUTURE 

 MANAGEMENT DECISIONS 



A. Reliability of Data and Estimates 



In light of the information so far presented, one 

 inevitably faces the problem of assessing the validity and 

 reliability of available data. Discrepancies in various 

 biomass, productivity, and consumption estimates for Antarctic 

 stocks prompts one to ask which estimates are most realistic. 

 Gulland (1976a) noted that there is not necessarily a single 

 best estimation method and that combinations of methods can 

 provide information on facets of a central theme. For 

 example, he stated that all that one could be sure of 

 regarding whale abundance is that: 1) visual observation 

 confirms whales' presence in the wild, 2) catch per unit 

 effort information confirms that fewer whales exist today 

 than before harvesting, and 3) that whale populations may be 

 increasing, based on comparing reproductive parameters and 

 other population characteristics. His point is that different 

 techniques will work more or less favorably for different 

 problems of estimation. 



Other factors affecting the relative accuracy of 

 different biomass or productivity estimates are the sampling 

 techniques and assumptions used when extrapolating sample 

 data to entire populations. The estimates of Southern Ocean 

 primary productivity previously discussed varied because 

 often different areas had been sampled at different times of 

 the year. These data were then used to describe the primary 

 productivity of large ocean sectors. These extrapolations 

 were made on the assumption that local measurements also 

 applied to larger areas. Whenever sampling techniques are 

 used to estimate biomass or productivity, the final estimate 

 is only as sound as the weakest assumption used in the 

 sampling data. 



When considering estimates of various features of the 

 Antarctic marine ecosystem, one aspect quickly becomes 

 evident: many of these calculations are made with minimal 

 data. Complex models will be of little use if based on 

 insufficient data. Theoretical treatments of various 

 ecosystem impacts or results of living resource exploitation 

 are important; however, without real information to test 

 hypotheses and to suggest new ones, understanding of the 

 Antarctic marine ecosystem will not improve. In light of 

 the gaps in our knowledge concerning virtually all aspects 

 of the Antarctic marine ecosystem, more data must be collected 

 in an organized and cooperative manner with specific goals 

 in mind. In the meantime, discussions should be undertaken 

 to determine the best techniques to estimate various parameters 

 using the minimal data currently available. 



