CPU stands for “Catch Per Unit” of effort. Tidy description eh? It is an actual measure used in actual research and actual population monitoring. See when the CPU gets lower we can infer the population is dropping. And when the CPU is more productive that means the population is rising. The unit in question is most often time. How many hours did it take for you to kill that many animals? Apparently our government agencies charged with stewardship don’t actually need to spend hours tracking or monitoring the population to understand these complex trends: We just need to ask the folk who are catching them how hard they had to work! Hey, why use time at all? It’s so ephemeral and who wears a watch anyway?
Why not BPU’s? (Number of beers consumed.)
Although used most often for fish, it was discussed in Oregon applied to beavers as well. See the CPUs for beaver are going down in Oregon, which lead to a voluntary moratorium on trapping in some parts of the state. I assume the CPUs for beaver are going up in Massachusetts, which is why folks always complain the population in the state is exploding.
Of course it doesn’t take into account the variability of Effort or Motivation or Skill. A place with trailing interest in/understanding of beavers could produce a low CPU and a place where everyone loses their collective minds when one is seen (Like MA for instance) could produce such a fire alarm effect that their CPU could be quite high. Not all beaver trappers are created equal.
In case it wasn’t clear, I don’t much like the statistic, or the idea of using murder rates as a way of tracking population. But I do like this one odd fact.
The CPU for Martinez California plummeted in 2007 to exactly zero.
Now for something completely different, I was sent this video yesterday by our old beaver friend and photographer Glenn Hori.