Hennessy

A targeted panfish survey using trap nets was completed in early June 2022 to provide updated information regarding Bluegill and Black Crappie size structure. Spring trap netting is the preferred method for evaluating panfish populations and was last completed in June 2015. Hennessy Lake is very similar to Fuller Lake which is connected just upstream through a navigable stream depending on water levels. Bluegill and crappie populations are very similar. A total of 133 Bluegills were captured over the course of two days/nights. Average length was 7.9 inches and maximum length was 9.2 inches. Ninety-two percent of fish measured were 7 inches or greater and 35 percent were 8 inches or greater. Five Bluegills (4 percent) measured 9 inches or more. A total of 43 crappies were caught; maximum length was 13.5 inches and the average length was 9.4 inches. Thirty-three percent of the sample measured 10 inches or larger and 12 percent measured 12 inches or greater. Hennessy Lake, like Fuller Lake, is situated in a peaceful setting with very little shoreline development. The lake is best accessed with a canoe, kayak or small boat. It's a small lake and there's a rich diversity of submerged, floating-leaf and emergent vegetation. The water is slightly stained and is more fertile than Fuller Lake. A few of the other species captured were Bigmouth Buffalo, Pumpkinseed and Northern Pike.

A spring panfish trap net assessment was conducted early June on Hennessey Lake to evaluate the Black Crappie and Bluegill populations which are the primary target species for anglers. This was the fourth panfish assessment conducted on Hennessey Lake. The 2015 panfish trap net assessment captured thirty-seven Black Crappie between 4.4 and 12.1 inches in length. Mean length for the sample was 9.4 inches. Crappie exceeding nine inches comprised 78% (n=29) of the catch with 43% (n=16) more than ten inches and 8% (n=3) exceeding eleven inches in length. All age groups 2-7 were represented in the sample with a prominent 2011 year class comprising 45% of the catch. Crappie growth rates were in the normal range when compared to work area averages. Bluegill catches in Hennessey Lake have ranged from 68 (2009) to 281 (2003) fish. Two hundred Bluegill were sampled in the 2015 spring panfish assessment. The fish ranged from 3.4 to 10 inches in length with a mean length of seven inches. The 2009 assessment had the greatest portion of the sample exceeding seven inches 56% (n=38) compared to 53% (n=106) in 2015, but the 2015 assessment had a greater proportion more than eight inches, 24% (n=49) compared to 13% (n=9) in 2009. Nine (4%) of the Bluegill were more than nine inches in length in 2015. Recruitment of Bluegill is very consistent with age groups 2-11 represented in the 2015 trap nets. Fast growth rates were observed for all ages. Game fish caught in the 2015 panfish assessment included twelve Northern Pike between twelve and twenty-three inches in length, one eighteen-inch Walleye, and one sixteen-inch Largemouth Bass. Additional species included Black Bullhead, Bowfin, Brown Bullhead, hybrid sunfish, Pumpkinseed, White Sucker, and Yellow Bullhead. Due to the small size of Hennessey Lake, low lake management priority and target management species, spring panfish trap net assessments will be used to evaluate the fish community.

Panfish in Hennessy Lake provide an important fishery in the area and a spring assessment was conducted in early June to evaluate the population size structure of black crappie and bluegill. Standard summer lake surveys typically do not sample many of the larger panfish that may be present in a lake. Four lake survey trapnets were set and lifted twice for a total of eight net lifts. The crappie, bluegill, and other gamefish were measured and scales taken from the panfish for age data. All other fish species were identified and counted. The 2009 spring assessment captured 37 black crappie (4.6/trapnet) between 3.9 and 12.5 inches in length. Mean length for the sample was 9.4 inches and modal length 10 - 10.5 inches. Larger crappie dominated the sample as 78% (n=29) of the fish were more than 9 inches in length and 56% (n=21) exceeded 10 inches. Ages 2, and 4 thru 9 were represented in the 2009 aged sample. Ages 2 and 7 exhibited normal growth while the remaining age groups showed fast growth. Year class strengths suggest low but steady recruitment. A similar panfish assessment in 2003 netted 44 crappie (5.5/trapnet) measuring from 4.8 to 12.2 inches in length. The size structure of the catch was not as desirable as that from the 2009 assessment. Both the mean length and modal lengths for the catch were shorter, 8.7 inches and 9 - 9.5 inches, respectively. While half of the fish (n=22) in the sample were more than 9 inches in length, only 7% (n=3) of the fish exceeded 10 inches. Bluegill were the most abundant species in the 2009 spring assessment, however, only 68 bluegill (8.5/trapnet) were caught compared to 281 (35.1/trapnet) in 2003. Size structure of the 2009 sample appeared to be more desirable than that shown in 2003. Mean length in 2009 was 7.1 inches and modal length of 7 - 7.5 inches. In 2003 the mean length was 6.2 inches with a modal length of 5.5 - 6 inches. Bluegill over 7 inches in length comprised 56% (n=38) of the 2009 sample with 13% (n=9) more than 8 inches and 1% (n=1) exceeding 9 inches in length. In 2003, bluegill measured from 3.2 to 8.9 inches in length. Fish exceeding 7 inches accounted for 22% (n= 63) of the catch while 5% (n=14) were more than 8 inches in length. Although the proportion of larger bluegill in the sample was better in 2009, there were more big fish in the 2003 spring assessment because of the sample size. Ages 2 thru 8 were represented in the 2009 aged sample with all age groups showing fast growth. Year class strengths suggest low exploitation as the majority of the fish appeared to be over 5 years of age. Five northern pike between 12 and 25 inches in length were also caught in the 2009 panfish assessment along with three largemouth bass between 11 and 13.5 inches. Other fish species netted included bowfin, brown bullhead, common carp, hybrid sunfish, pumpkinseed, white sucker, and yellow bullhead. An area mean back-calculated length table was used to compare growth of the crappie and bluegill.

Based on Minnesota DNR survey data, anglers target Black Crappie, Bluegill, Northern Pike, Hybrid Sunfish, and Walleye in Hennessy. See the full species list above for catch rates, size structure, and quality scores.

Minnesota DNR records list public access for Hennessy. Check the DNR LakeFinder page for the launch type and directions before you go.

Hennessy has a maximum depth of 32 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Hennessy is from 2015. Surveys this old should be treated with some caution — fish populations change over time.

No invasive species are on record for Hennessy in Minnesota DNR data. Always clean, drain, and dry your equipment to help keep it that way.