Agassa Lake is in Ecological Lake Class 17, which consists of 99 lakes in northeast Minnesota that are small, very shallow, and have bog stained and very soft (low mineral content) water. Agassa Lake does not stratify during the summer and retains good oxygen to near the bottom. A small inlet drains a swamp, and the outlet to Big Lake has beaver dams and flows through swamps which limit fish movement. Shallow water lake bottom substrates are mostly ledgerock, boulder, and muck. Aquatic plants are sparse and grow to a depth of 8 feet.
The 2009 population assessment consisted of two gillnet sets. Six previous fisheries investigations, dating back to 1977, also consisted of two gillnets sets. Trapnets have not been used in Agassa Lake due to the difficult portage access.
Fish populations in 2009 consisted of walleye, yellow perch, and high numbers of white sucker. The total catch of fish (all species combined) in 2009 of 40.5 fish/gillnet (42 lbs/gillnet) was lower than the median (45.5 fish/gillnet) of all investigations on this lake.
Walleye were absent in the initial survey in 1977, and walleye stocking began in 1982. Agassa Lake has been stocked biennially with walleye fry since 1993 with the most recent stocking in 2009. The walleye catch rate in 2009 was identical to the median (5.5/gillnet) of all investigations since walleye first appeared (1984-2009) and in the third quartile for Lake Class 17. Walleye sizes averaged 13.3 inches in 2009, lower than the average from all previous investigations of 14.1 inches. The largest walleye caught in the 2009 assessment was 16.5 inches. The 2009 catch was distributed relatively evenly across 6 age classes (Age 2-8). Growth varied widely by age class, due in part to small sample sizes.
The 2009 white sucker catch rate (28.5/gillnet) was above average for Lake Class 17 but at the median of all investigations on this lake. Sucker numbers in Agassa have been high in all investigations, ranging from 22.5/gillnet to 40.0/gillnet. The average white sucker size in 2009 was 14.3 inches; the largest was 19.9 inches.
Yellow perch numbers in 2009 (6.5/gillnet) were normal (in the second quartile) for this lake class and at the median of all Agassa Lake investigations. Perch numbers have varied widely in previous assessments, ranging from 4.5/gillnet to 28.0/gillnet. The largest yellow perch caught in 2009 was 10.5 inches, but perch size averaged 9.3 inches. The 2009 catch was dominated by age 3 and 4 fish. Growth was faster than normal (in the fourth quartile) by area standards.
None of the fish examined in 2009 had signs of parasites or diseases.