Paul... that's because there is no relationship between survival rates of sea otters, star fish and forest service employees.  Sea otters are not mentioned because the essay has nothing to do with them. I'm sorry you have a misunderstanding of global warming and the science behind ocean acidification and how it is impacting Alaska. 

Sea otter impacts on local shellfish populations should be the least of your concerns. GW will overwhelm any impact of otters on shellfish in the near, not the far away future.