What do jiro and sons believe has affected the availability of high quality tuna? select one:

a. global warming

b. the proliferation and growing popularity of sushi worldwide

c. pollution

d. the absence of fishing regulations

e. all the above?

I believe the answer is: D. The absence of fishing regulations

The absence of fishing regulations make a lot of fisher able to choose a fishing method that either damage the ecosystem under the sea or using a chemical that may alter the biological composition in the fish, and both of these things reduce the availability of high quality fish.