Threats to the vaquita include habitat changes caused by water abstraction from the Colorado river which drains into the upper Gulf of California, but the primary threat is probably that of bycatch in gillnets used to catch fish in the area. The fisheries that cause the bycatch problem are based in three ports in the upper Gulf of California. A large number of independent fishermen use small skiffs to fish for a variety of different species throughout the year using nylon gillnets.
Fishing is the primary economic activity in all three ports.
Tourism is the second most important activity in two of the ports, although this is seasonal. In the other, there is little alternative employment. Your assignment is to use a simple mathematical model to assess just how endangered the vaquita really is, and to decide what could be done to save it. Population viability analysis PVA is a method where a model is used to project what will happen to a population in the future, given different management regimes. However, the deterministic logistic model doesn t allow for the fact that the world is not that simple.