YOY is an acronym
f the Y
ear. It is pronounced so as to rhyme with "toy" or "joy."
YOY is used as a technical term in fish research and in dolphin research (the mammalian dolphins).
It is useful to designate YOYs in conditions when exact birthdates or ages are difficult to determine, and when babies less than a year old are identifiable.
Examples of Usage (in dolphin research):
"That last group had two YOYs, one subadult, and four adults."
"I saw the cutest YOY in the field today! I think I got a photo."
"Two people have reported seeing FB90 with a YOY over the past few weeks, so see if you can find her today."