Just found a YouTube video of Manabu's world record catch.
http://www.youtube.com/watch?v=HXOyXArL9rw
I see where you getting at and you make a good point, but just because Japan considers them to be a "junk" fish doesn't mean everyone is targeting them.
Plus the lake this LMB was caught in, (Lake Biwa) is the largest lake in Japan, covering some 259 square miles(sooo much bigger than Castaic), and is said to be one of the oldest lakes in the world, so these bass have alot of area to roam and alot of food to feed on without the worry of preditors.
I'm thinking will see another record bass pulled out of this Japanese lake again real soon.