Landed or descended is the best option as that is the meaning of alighted
Fast growing Salmon to me would be a freak of nature. Most likley some idiot put some steriods in the ocean, but also must mean something is happening with where they live and they are trying to adapt to what has happened.
Accede is a synonym of acquiesce.
Acquiesce is a synonym of accede.
As verbs the difference between acquiesce and accede is that acquiesce is to rest satisfied, or apparently satisfied, or to rest without opposition and discontent (usually implying previous opposition or discontent); to accept or consent by silence or by omitting to object; — followed by "in", sometimes also by "with" and "to" while accede is (archaic|intransitive) to approach; to arrive, to come forward.
