The one in 30 million statistic is crazy to me! That means that the surviving fish need to average 30 million children in their lifetime to sustain the current population - if they stay adults for 2 years, that's 41,000 children per day! Can someone shed light on how that's possible?

Note also that it's 1 in 30 million babies that actually hatch that survive, not just 1 in 30 million eggs.