Between 2000 and 2010, the number of bass in the Mississippi River and its tributaries experienced a catastrophic decline. There is little evidence that pollution or disease was the cause, so it is likely that there was an increase in the number of bass killed by other means. Typically, recreational fishermen in the region prefer to pursue several varieties of river trout, but a state law passed in 2001 banned the catching of trout in the area. Thus, it is likely that recreational fishing was the immediate cause of the decline of the bass population.
Which of the following, if true, most strengthens the argument?