For years fisherman visiting Canada were puzzled as to why some lakes were jam packed with small walleyes and virtually no big fish, when another nearby body of water, sometimes even connected, consistently produced a good mix of small and big fish. The cause for the difference in size structure can often be attributed to the presence of a single species of bait fish.
Biologists have determined that one of the key forage required to consistently produce big walleyes on the Canadian shield is the ciscoe. This high fat content bait fish is the “Bacon Double Cheeseburger and Strawberry Shake” of the walleye diet. Without them, walleyes have a difficult time exceeding the 5 LB mark, regardless of how long they live.
Ciscoes like it cool. When water temperatures exceed 70 degrees F for any length of time, they die. Unless, unless they have a cool deep water basin to hang out in. Once again, were back to talking about large, deep lakes. There are occasional exceptions to the rule, but when you are looking for consistent catches of big walleyes, big water is the answer!
Pike are less dependent on a single species to attain maximum size, but big Northerns do have a specific problem in Summer. Like ciscoes, big pike can’t take the heat. Big females have a low surface area to volume ratio and have a difficult time getting rid of excess body heat. When the Summer sun heats up the shallow bays, the big pike seek refuge in the cooler main lake basin for most of the day.
Without deep water or an abundant forage base near deep water, it is difficult for the bigger fish to survive let alone thrive. With a surface area of 560 sq. miles ( 358,290 acres) and nearly 3,000 miles of shoreline, Lac Seul is the 2nd largest inland lake in Ontario, and definitely satisfies all of the structural requirements of a Trophy Canadian Shield Fishery.