HEre’s the post about the tainted fish in San Diego.
The radioactive waste which contaminates seaweed enters the food chain (fish eaten by fish etc.) and concentrates in the larger predators which we tend to eat. There are alot of ways radiation in the ocean bad, the food web is one example.
"Bluefin tuna fish caught off the California coast are indeed safe to eat: the levels of radioactive cesium found in the tuna, between 5-10 becquerels (Bq), are far below the Japanese-set seafood safety limit of 100 Bq/kg, which was just reduced from 500 Bq/kg in April. And the levels are also lower than doses of naturally occurring isotopes in fish, such as radioactive potassium and polonium, said Buesseler."
So while things appear a little hairy around Fukushima, we can relax on this side of the ocean.