Which of the following does not represent a reduction in animal use?

The option that indicates a situation that does not represent a reduction in animal use is the introduction of a new anesthetic that provides better induction and a shorter recovery period. While the anesthetic may enhance the welfare of the animals by reducing the time they spend in recovery, it does not inherently decrease the overall number of animals utilized in research. The focus here is more on improving the quality of care and procedural efficiency rather than on minimizing animal usage.

In contrast, the other choices illustrate clear strategies aimed at reducing animal utilization. Shared tissue use among multiple investigators maximizes the value of each animal, thus conserving resources. Improved assays that yield better data precision directly reduce the number of animals needed for statistically significant results, resulting in fewer animals being sacrificed for the same level of scientific inquiry. Lastly, employing common control groups during concurrent experiments helps decrease the total population of control animals required, as these animals can serve multiple experimental purposes. Collectively, these options characterize effective methods for minimizing animal use in research settings.