IELTS Writing Task 1: life cycle mistakes

Can you correct the mistakes in the following six sentences?

1. Salmon begin their lives from eggs that laid in a river.
2. After emerged from eggs they reared to freshwater.
3. Before they merge to sea they stay in estuary, where sea and river meet.
4. During their time in the ocean, young salmons develop gradually into mature salmons.
5. The adult fishes travel to spawning areas where the salmon incubation can be done.
6. Their cycle completes when the spawning process starts and as some research, adult salmon die right after that due to exhaustion.