The weight of each fish would be multiplied by 10.
Assume the first time, the weight was 800 lb. Since there were 100 fish caught, the weight of each fish would be 800/100 = 8 lb.
This time, however, only 10 fish were caught. The weight would be 800/10 = 80 lb.
80 = 8(10), so the weight is 10 times more.