speaking of sushi, here's a video about the extinction of blue fin tuna (includes economics, history, culture): https://www.youtube.com/watch?v=hivvTo6VSS8
See Oceanwise's salmon recommendations:
The crystallization process in this case means that the solid crystal formed by water freezing into ice ruptures all of the cell walls, releasing their contents. Once that happens the chemistry of the food can change drastically as enzymes and proteins that were once only active inside cells are now floating everywhere.
In the case of frozen salmon, the taste appears to come from some sort of enzymatic process involving fatty acids [1].