Data on bycatch is often unclear and not well recorded but it is estimated that the U.S. alone discards 17-22% of their catch annually.[8] The Mesopredator release hypothesis is one of the indirect effects of overfishing that is also often referred to as "fishing down the food web". This phenomenon means as fisheries deplete large apex predatory species, mid-sized predatory species increase in abundance and assume the role as top predators on the food web.[9] This impacts the food web in marine environments and disrupts the balance of the ecosystem and is likely to cause trophic cascades.