Question

A fisheries biologist tells you she is studying a cohort of salmon returning from their birth river. What can you infer about those salmon?

a. They are iteroparous
b. Most of them are one to three years old.
c. They are the same age.
d. They have uniform distribution.

Answer 1

The cohort of salmon studied by a fisheries biologist are a group of salmon returning to spawn in their birth river and are the c. same age as they originate from the same spawning event.

Step-by-step explanation:

When a fisheries biologist mentions studying a cohort of salmon returning from their birth river, it refers to a group of salmon that originated from the same spawning event and are therefore roughly the same age, which is option c. Salmon are known for their anadromous life cycle, migrating from their freshwater birthplaces to the ocean, and then back again to spawn.

Typically, the migratory phase in the ocean lasts from one to four years, so the returning cohort could vary in age but all members of the cohort would have left freshwater at the same time. However, they are not necessarily iteroparous since not all salmon survive the spawning journey to reproduce again, and option b is not accurate because salmon can be older than three years when they return to spawn. Also, their distribution pattern is not necessarily uniform as it can be affected by various environmental factors.