Pokegama Lake is located next to Grand Rapids, Minnesota. The lake has seven public accesses and is highly developed. The 2011 lake management plan (LMP) indicates Walleye, Muskellunge and Northern Pike as the primary species of management with Largemouth Bass and Smallmouth Bass as secondary species. The LMP goals include maintaining the Walleye gill-net catch greater than 8.0/net; reduce the Northern Pike gill-net catch to 5.0/net with 50% of the fish exceeding 21 inches and having 34 plus inch fish present; maintain Largemouth Bass and Smallmouth Bass electrofishing catch rates at 35 and 15 per hour; and provide Muskellunge fishing opportunities.
A standard survey was conducted in July of 2015 to assess the fish community. A total of 15 gill nets and 15 trap nets were used in the survey as well as spring night electrofishing for Largemouth and Smallmouth Bass. Catch rates were likely lower than normal during the week of netting because of the extreme wind that even rolled some gill nets.
Walleye catch rates have fluctuated from 1.6 to 10.8 fish/gill net since 1949. The Walleye gill-net catch declined from 8.2 fish/net in 2010 to 4.7 fish/net in 2015. The catch fell short of the ambitious management goal of 8.0 fish/net but was within the normal range for the lake class. The sampled fish ranged from 7.8 to 28.7 inches and averaged 17.4 inches.
Past evaluations determined Walleye natural reproduction was sporadic in Pokegama Lake. It appears that large, deep lakes do not warm fast enough to produce sufficient food for fry to survive. Walleye fingerlings can often be an effective management tool in these types of lakes where fry and natural reproduction have not been successful. The 2015 survey evaluated a period in which Walleye were stocked annually since 2004. Twelve age-classes from age 1 to 12 were identified. Walleye averaged 16.4 inches after four years of growth, which was similar to the statewide averages.
Muskellunge are not sampled well with standard summer surveys because they exist in very low numbers. Spring surveys are used to evaluate adult Muskellunge populations because the fish concentrate in the shallows for spawning. Spring surveys have not been used to sample Muskellunge on Pokegama Lake yet because the population is still developing.
Northern Pike gill-net catch rates have ranged from 4.1 to 10.6 fish/net since 1949. The catch rates have been increasing and the last two were the highest on record. The catch was 9.8 fish/gill net in 2015. The catch did not meet the LMP goal but the size structure goals were minimally met. Northern Pike ranged from 9.8 to 38.8 inches and averaged 21.6 inches. Nine age-classes were identified with fish from age 1 to age 9 present. Three and four year old fish represented 60% of the sample. Growth was similar to or better than statewide averages for all ages. Northern Pike averaged 23.7 inches after four years of growth. The Northern Pike population shows some signs of quality overharvest because of the increasing catch rates and the low number of fish over 24 inches in the size distribution.
Largemouth Bass were sampled with spring night electrofishing for the fifth time since 1995. Electrofishing catches have ranged from 3.7 to 55.6/hr. In 2015, the catch was 32.4/hr which achieved the LMP goal. The sampled fish ranged from 5.6 to 19.2 inches and averaged 12.0 inches. Nine age-classes were identified from scales with fish from age 2 to 10 present. Two to four year old fish represented 67% of the sample. Growth was similar to statewide averages for all ages.
Smallmouth Bass were also sampled with spring night electrofishing in 2015. The LMP goal was achieved with a catch of 18.0 fish/hr on-time. The sampled fish ranged from 7.3 to 18.7 inches and averaged 13.2 inches. Five age-classes were identified with fish from age 3 to age 9 were present. Growth was similar to the statewide average through age 4 and slower for older fish.
Black Crappie are often difficult to sample during summer surveys because they frequently suspend in areas where the nets do not fish. Consequently, catch rates have always been low and likely do not reflect the population well. The gill net and trap net sampled fish ranged from 4.2 to 14.2 inches. Age and growth information was not collected during the summer survey.
Bluegill catch rates have been trending up since 1975 when only 0.5 fish/trap net were captured. The highest catch (31.1 fish/trap net) occurred in 2010. In 2015, the catch was 17.8 fish/trap net. The sampled fish ranged from 3.0 to 8.4 inches and averaged 5.2 inches. Age and growth information was not collected during the summer survey.
Tullibees are difficult to sample with our standard summer nets because they frequently school in the open water where our nets are not effective. Catch rates on Pokegama Lake have ranged from 0 to 8.2 fish/gill net but have not been above 0.5/gill since 1984. The lower catches in recent surveys correspond to the illegal introduction and expansion of Rainbow Smelt before 1984. Rainbow Smelt have been documented to have a negative effect on Tullibee populations. The catch of 0.1 in 2015 was low for lakes like Pokegama. The two sampled fish were 19.3 and 20.0 inches. Some Tullibee were noted in Walleye stomachs.
Yellow Perch catch rates have fluctuated from 4.8 to 43.7 fish/gill net since 1949. The 2015 catch was the lowest on record. The Rainbow Smelt die-off during the summer of 2011 likely shifted additional predation towards Yellow Perch. It appears the additional predation reduced Yellow Perch recruitment, resulting in the lower catches. Yellow Perch numbers may already be improving based on the fall small-mesh gill-net catches in 2015. The Yellow Perch during the summer ranged from 5.2 to 10.9 inches and averaged 6.8 inches.
Other species observed during the survey included Bowfin, Hybrid Sunfish, Pumpkinseed Sunfish, Rainbow Smelt, Rock Bass, Silver Redhorse, White Sucker, and Yellow Bullhead.
In order to maintain or improve fish and wildlife populations, water quality and habitat must be protected. People often associate water quality problems with large-scale agricultural, forestry, urban development or industrial practices in the watershed. In reality, the impact of land use decisions on one lake lot may be relatively small, yet the cumulative impact of those decisions on many lake lots can result in a significant decline in water quality and habitat. For example, removing shoreline and aquatic vegetation, fertilizing lawns, mowing to the water's edge, installing beach sand blankets, failing septic systems and uncontrolled run-off, all contribute excess nutrients and sediment which degrade water quality and habitat. Understanding these cumulative impacts and taking steps to avoid or minimize them will help to insure our quality fisheries can be enjoyed by future generations.