After the drought, $TUNA was the only real source of food left in the Wasteland. Some greedy gangs of Feles tried to control the supply but all that ended up accomplishing was tearing each other down. Now Feles have no choice but to scavenge the Wasteland for any $TUNA that they can get their paws on.
The only way to find $TUNA is by sending your Feles out to scavenge the Wasteland. Each Feles has different scavenging prowess which is directly proportionate to their rank, energy, the demand for $TUNA (LP):
Energy = energy ranges from 1-8 and is determined by the length that a Feles is staked for as well as it's state (see True Form)