개체수가 · 개체수를
population (number of individuals of a species)
Example
보호 활동 덕분에 반달가슴곰의 개체수가 늘었어요.
Thanks to conservation efforts, the Asiatic black bear population has grown.
Word parts
개 individual+체 body+수 number
Literally 'number of individual bodies'.
Good to know
Pronounced [개체쑤]: 수 becomes tense.