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Two computer-assisted photo-identification methods for sperm whales (Physeter macrocephalus), namely the Highlight method (Whitehead, 1990) and the Europhlukes method (based on Huele et al., 2000), were compared. Performance was measured in terms of speed and accuracy. A test set was constructed containing two photographs of each of 296 individuals. The test set was divided into three classes of photographic quality and three classes of pattern distinctiveness. Both programs met requirements for rapid matching; the mean extraction times were 74.2 and 90.1 s per image for the Highlight and the Europhlukes methods, respectively. The two methods performed similarly with respect to accuracy. Accuracy improved by using higher-quality photographs or photographs representing more distinctive flukes. Still, even when using only the higher-quality photographs, 12.4% of the matches were not included in the top nine of the list of potential matches by the Highlight method compared to 14.0% for the Europhlukes method. The rate of failure to find the true match in the top nine was only 3.3% when both methods were used together, however. It is, therefore, recommended that for improved matching, both methods should be used in tandem or that an integrated program, which combines the two methods, should be developed.

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In the tradition of the study of materials flows through society, the Substance Flow Analysis (SFA) method and its software tool SFINX are presented. SFA aims at providing the relevant information for a country's overall management strategy regarding single substances or coherent groups of substances. Three modelling techniques and their possibilities and limitations are discussed: Bookkeeping, static modelling, and dynamic modelling. The computer program SFINX can be used for varoius purposes: (1) to obtain an overview of stocks and flows of a substance in, out and through a nation's economy and environment for a specific year, (2) to trace the origins of specific pollution problems, and (3) to estimate the effectiveness of certain abatement measures. Each application has its own requirements with regard to data and modelling.