I've been looking for a word which is very close semantically to 'overpopulation'. Popular Internet dictionaries show words like 'overcrowding' or 'congestion', which are too general for me. I know that there is no such thing as 'the exact synonym', but if anybody can think of anything more adequate than my examples, I would be delighted if that person shared it with me.
Maybe you can use the phrase exceedance of carrying capacity to describe an overpopulation?
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.
Or simply, a teeming population.
I know I'm a little late to the show. But, as a student of this issue, I would note that "overpopulation" has become a controversial phrase; many reflexively reject the concept out of hand. Maybe try: seeking "optimum population," a phrase that's more current and less apt to incite grow-the-economy-at-all-costs types.