Portage Lake is a moderate sized, shallow lake with bog stained water and abundant aquatic vegetation, and is located in central Aitkin County. There is a public access with a concrete log ramp in the southwest corner of the lake. Although the lake has historically experienced occasional winterkill conditions, there have been no such events observed recently. Light residential development is concentrated on the eastern shore, with some scattered development along the west shoreline.
Northern pike and black crappie are the main species targeted by anglers. Pike abundance in gill nets was within the normal range for similar lakes. Average size of fish was respectable at 22.5 inches and 2.8 pounds. Length ranged from 16.5 to 27.7 inches with 31% greater than 24 inches. While catching large pike (greater than 24 inches) can be exhilarating, anglers are encouraged to release large fish due to their role in maintaining quality size structure of many species, and to maximize the sporting benefit for multiple anglers by recycling these quality fish.
Black crappie were captured within the normal range in both gill nets and trap nets. Fish from trap nets ranged from 4.5 to 10.5 inches, but averaged just 6.0 inches. A one-day spring trap net assessment was conducted in addition to standard survey netting. Spring sampling captured crappie up to 14 inches, but the average size was still only 6.2 inches. Fish growth was slow compared to county and state averages.
The spring trap net assessment also provided some additional information about the largemouth bass population, since only one bass was sampled with standard survey nets. Although not abundant in spring trap nets (13 fish total), size was impressive with fish ranging from 12.2 to 21.3 inches, and averaging 17.5 inches and 3.1 pounds.
Bluegill abundance in trap nets was normal, but size and growth was poor. Only one bluegill over 7 inches was sampled during this assessment. Age analysis nearly annual recruitment, with nine year-classes identified. However, bluegill grew to just 5 inches long in six growing seasons, which is well below average for the area.