Complex sentence: In the elaborate First Salmon Ceremony, which is still observed, the entire community shares the flesh of a Spring Chinook, then returns its remains to the river where it was caught, so that it can inform the other fish of how well it was received.
Split into simpler sentences: In the elaborate First Salmon Ceremony, which is still observed, the entire community shares the flesh of a Spring Chinook, then returns its remains to the river where it was caught. This is so the salmon can inform the other fish of how well it was received.