it's basically a two pronged issue.
climate change is really messing up the aquatic ecosystem, and that is bad news for balance on the planet.
Pollution is another major issue as any significant change in shallow breeding waters can affect the success rates of the spawning cycle.
and lastly, over fishing. Ya, there's a demand because people refuse to use birth control and limit the staggering over population we have on this rock. We aren't helping the 3rd world people through education and finance and to be honest, all religion is fucked and creates an impossible scenario for basic common sensical population sustainability.
Don't worry, "God" will make a big flood that will kill all the bad folk and put everything back on order.