The whales, first spotted Sunday in the lower Sacramento River, likely were on their northward migration from Mexico up the California coast when they were sidetracked, biologists said.

• 两只鲸鱼是在周日于沙加缅度河下游一带首度被发现，他们很可能是在从墨西哥沿加州海岸往北迁徙的过程中误入歧途，生物学家说。