This feeding technique is what makes the northern pike a favorite for sport fishing fanatics. In a study done in Sweden by P. Anders Nilsson and Christer Bromark, it was found that pike are limited in what they can eat only by the body depth of the prey that they are consuming. They studied two different kinds of common northern pike prey and used body size as a differentiating factor. In both types of prey, the pike chose to eat the fish that had shallower bodies, and the length of the prey did not matter. This is due to the gape size of the fish's mouth.
Northern pike have to re-orient their prey before they can swallow it.
Commonly a pike will carry it's prey like a dog would carry a bone, perpendicular to the pike's body. Then before swallowing the prey, they will flip the prey and swallow them head first. In fact, the pre-spawning movements into the shallow waters are underway before the ice is out. It begins when a large female, usually accompanied by several much smaller males, seeks out a spawning site. This area is usually a shallow marshy area of a stream or lake.