Thinking About Nature

Can There Be an Optimum Population Size for Any Wildlife?

One of the goals of wildlife management and conservation — ever since this activity became a profession, with university departments granting degrees in wildlife management — was to act to maintain a maximum sustainable yield from that population. Then, in the second half of the Twentieth Century, when conservation came more to the fore than simply harvesting wildlife, the goal shifted some of the time to maintain an optimum sustainable population.

In 1972 Congress passed a remarkable innovative piece of legislation, The Marine Mammal Protection Act. One of its primary goals is to insure that every marine mammal population should be not be allowed to diminish below its optimum sustainable population.

The Act created a Marine Mammal Commission, and a few years after the Act was passed, that commission came to me with a question. The Commissioners said that they could not determine what an optimum sustainable population could be — could not figure out how to define it or make it quantitative. They asked if I would analyze the Act and write a report about this concept, given the wording of the Act and how it could make sense ecologically.

This seemed to be an environmentally important question and one that ecologists should tackle, so I agreed to take on the task. I invited Dr. Matthew J. Sobel to join me, because he was an expert on business (later Dean of a Business School), had worked for on environmental problems for the precursor of EPA, and was an applied mathematician with expertise in stochastic processes, and understood both economics and ecology. We wrote a report, which you can read here. We thought we had simply read the law objectively and analyzed what it said from both a legal and ecological point of view, in a neutral but thorough way. But to put it mildly, our report was controversial. Although it was written in the 1970s, it has information and analyses that I believe are still important for the conservation and management of wildlife and for ecology, and therefore we are making the report available to you. Comments are welcome.

Download the paper.