Collective strategies are possible within a population. Such situations occur in nature with birds or fishes in flocks. Such swarm intelligence problems are suitable for optimization problem-solving. Other co-evolutionary models implicate two different populations or species which compete. In the predator-prey model, the predator eliminates the weak prey. We show that such a situation can be transposed to optimization problems, for which the predator is one of the objectives, and the preys are feasible solutions. Solving an MOO problem may use different ways. One way consists of decomposing the initial problem into a sequence of subproblems.