What is happening now could mark one of those seachanges in public policy that seem to come along once in every generation.
今日之事，不过是每代人都会经历一次的公共政策变化罢了。
2
That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes.
这意味着更多的海洋生物正在被捕捞，所以现在和过去之间的真正差异可能比捕捞量变化所记录的更糟糕。
3
Changes in climate before that period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.