Fairly weak study.
Fish size is determined by a multitude of factors.
Water quality being #1 with food supply a close second. Population, or how much competition there is for the food supply is probably the next biggest factor. Predation, to include over fishing, is likely next on the list.
For example, the average size of many big game fish like marlin and tuna have shrink in recent decades because of over fishing. Their food supply has been reduced by overfishing and pollution and they are simply not living long enough to get large because they are overfished.
But if this study and its prediction is treated as valid, a global warming supporter could look at the raw data on game fish size and proclaim the size reduction is because of global warming over the same period of time. They would be, as this study is doing, ignoring other factors.
This is a very simplistic study of one tiny aspect of fish life. The entire purpose of this study is to make a dire prediction in an attempt to reinforce the crumbling case for manmade global warming.
