A researcher hypothesizes that the recent decline of a particular salmon population is caused not by ocean conditions, as is widely assumed, but by changes in freshwater spawning streams that reduce juvenile survival.
Which finding, if true, would most strongly support the researcher's hypothesis?
- Acheck_circle
Tagging studies show that juvenile salmon survival rates in spawning streams have plunged in recent years, while ocean survival of salmon that successfully reach the sea has remained stable.
- B
Some salmon species spawn multiple times in their lives.
- C
Salmon populations have varied for thousands of years.
- D
Salmon are an important food source for many wildlife species.
Explanation
A isolates the freshwater stage as the bottleneck while ruling out ocean conditions, exactly as the researcher hypothesizes. B, C, and D are tangential.