To identify that the part of that water is clean it should have a lot of seaweed and if there not that much seaweed and you sea a lot of kina that mean it over fishing in marine reserves the water is clean and you can’t feed human food to the fish or they will just eat the human food and there not eating there own food and it can disturb the the circle of life and the kina might come to eat the seaweed and in the pollution
Overfishing is very bad for the environment if you get too much, snapper and lobster the kina eat the seaweed to and over populate.