How much seafood would I have to eat to get mercury poisoning?

I eat a canned tuna sandwich twice or three times a week, sashimi about once a week, shrimp once a week, salmon once or twice a week (plus other types of seafood that I’m neglecting to remember)… and I’m only 15.

Do you think if I keep up this eating habit later in my life that I’ll be at risk for high mercury levels?

You could be at a higher than normal risk, but I wouldn’t fret about it. You are a growing young adult. Eventually, you will get tired of seafood. Your tastebuds will change, and you will have little or only a small desire for seafood. If your body demands seafood, feed it seafood. It apparently likes the omega 3 in it!!

I wouldn’t worry about it now but if you are still eating like that when you are 24 or 25 I’d probably get tested for Mercury poisioning by then.

By the way, you might want to consider cutting down on your seafood intake a little bit unless you don’t get any red meat.
If you never have red meat or chicken in a normal week then the fish is just making up for it.