What is the term for the growth rings used to determine the age of fish?

The term for the growth rings used to determine the age of fish is "Annuli." This term specifically refers to the concentric rings formed on structures such as scales, otoliths (ear stones), and fin rays of fish. Each annulus typically represents a year of growth in the life of the fish, allowing biologists and researchers to assess the age and growth rates of different species.

Understanding how to read annuli is crucial in fishery biology, as it helps in managing fish populations and ensuring sustainable practices by estimating age classes, growth rates, and spawning aspects. The identification of annuli is essential for studying fish ecology and fisheries management practices.

The other terms provided do not accurately describe the specific structures or means involved in determining fish age: "nuclei" usually refers to the center of cells or atoms and is unrelated to fish growth; "layers" is too vague and does not convey the specific chronological significance of the rings; and "growth bands" could be confused with other forms of growth measurement that are not necessarily annual.