In order to minimize the risk of biological invasions in a country called Home, a seaport manager must inspect a certain number of arriving ships successfully in a time period of interest. Given that inspections are costly, how should our seaport manager, interested in minimizing the total expected cost of inspections, allocate resources for conducting these inspections? More specifically, what is the relationship between the resources allocated to inspections and (i) the number of successful inspections that still need to be conducted in the pertinent time period and (ii) the number of stages remaining in this same time period? In this paper, we conduct a dynamic and stochastic analysis of the above two significant but insufficiently studied questions in the existing literature on alien species management.