The problem with this sentence is that there is no subject-verb agreement.
The subject-verb agreement implies the verb should agree with the subject on the number (singular vs plural). Here are some examples.
The sentence about whales does not show the subject-verb agreement. This is because in the section there is approximately 2,200 blue whales the author is using a singular verb is to refer to a plural subject 2,200 blue whales.
Note: This question is incomplete; here is the complete question:
What's wrong with this sentence: "Today there is approximately 2,200 blue whales in the eastern North Pacific and research indicates that the population hasn't changed significantly since 1993"
Learn more about plural in: https://brainly.com/question/4417996