Is there a correlation between (green) sea turtle size and it having barnacles?

Hi, I'm doing a stats project for school and we're working with sea turtle data. We have to look at our initial data and do research based on what our question/hypothesis is. Our data clearly shows that smaller turtles tend to have barnacles, but what's the reason for this? Do barnacles limit turtle growth, do bigger turtles have an easier time cleaning barnacles and are therefore less likely to have them, or is it something else?