Jake,It makes sense to me. As a boy fishing off the west coast of Scotland I was amazed at what we found inside the cod we caught. We always found bits of crab - and a couple of times I remember finding whole live crabs.Its then a matter of standard ecology. Remove the predator, and the prey will increase to reach a different equilibrium - either as their food runs out - or due to predation by fishermen. The key issue here is likely to be the relative rates of growth/predation rates of cod and crab. Removing the limiting factor in most systems leads to exponential growth - followed by a crash as the system overshoots.