How do mergansers catch and hold fish?

Mergansers are specialized diving ducks within the order Anseriformes that have evolved specific anatomical features to effectively catch and hold fish.12

They utilize a distinctive, long, and narrow bill that is equipped with toothlike projections along its edges, which function to grip slippery prey. Additionally, the tip of the bill is hooked, further assisting in the capture of fish. To ensure a secure hold, their tongues are also adapted with two dorsal rows of barbs.123