Wednesday, February 1st, 2023
Wednesday, February 1st, 2023

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Wisconsin Lake Profile – Diamond Lake, Bayfield County

Future looks bright on Bayfield County’s Diamond Lake


DNR Report


The local DNR fisheries team surveyed Diamond Lake in 2018 and 2019. Diamond continues to support a diverse fish community and popular sport fishery. Natural reproduction supports all species in Diamond Lake, except for walleyes (supported by stocking). Harvest regulations aimed at protecting adult walleyes have been successful. Northern pike harvest management has shown mixed results. The recent changes in harvest regulations for bass are too recent to show any major results.


Results from the 2018-19 survey suggest that walleye regulation change (15-inch size limit, protected slot limit of 20 to 24 inches, and a bag limit of three fish with only one over 24 inches) still has been successful in protecting adult walleyes. Average length of adult walleyes in 2018 was 22.5 inches, so the regulation can maintain the excellent size structure of walleyes in Diamond Lake.


The walleye harvest was down in 2018, most likely due to the lowest fishing pressure for walleyes in the eight survey years. The decrease in harvest also may show that the new regulations implemented in 2016 still protect the adult walleye stock.


Walleye densities decreased significantly from 1990 to 2012 and have increased all that much from 2012 to 2018 (1.3 adult walleyes per acre) and are still slightly below the ceded territory stocked lake recruitment code average of 1.6 adult walleyes per acre.


The success of stocking small fingerlings decreased during the survey years. No natural recruitment and minimal success of small fingerling stocking could be attributed to the significant decrease in walleye abundance from 1990 to 2012. Large fingerlings have been stocked since 2007 and have shown stronger recruitment


The success of the northern pike regulation (26-inch size limit and a daily bag limit of two fish) is hard to evaluate. Fishing pressure for pike was the lowest it has ever been and the lowest for all game fish species. Estimated harvest of pike was also down. Pike sampled in 2018 had an average length of 23.2 inches, so the size structure may be increasing. However, the proportion of larger fish has declined significantly over the survey period. Spring fyke netting in 2018 sampled six northern pike over 26 inches. Predicting how the 26-inch/two-fish regulation will change Diamond’s pike populations is difficult; there are other factors that influence pike.


Water clarity and pike density have been shown to negatively affect northern pike size structure. Diamond has very clear water, so this could be a factor limiting northern pike growth. Density of northern pike in Diamond Lake is relatively low at 1.6 northern pike per net lift, meaning this shouldn’t be a limiting factor in size structure.


Largemouth bass abundance had increased significantly from 1996 to 2009, then decreased very slightly from 2009 to 2018. Largemouth abundance increased by 306% from 1996 to 2018. Their average during spring electrofishing was 13.1 inches, the highest for all survey years. Smallmouth bass abundance decreased from 1996 to 2009 and fluctuated from 2009 to 2018 with an overall significant decline. Smallmouth bass abundance in 2018 was down 73% when compared to 1996. Historical surveys on Diamond Lake indicated smallmouth outnumbering largemouth bass. Smallmouth bass also outnumbered largemouth bass at a ratio of 2:1 in 1996 surveys. However, surveys in 2009 and 2018 showed largemouth bass outnumbering smallmouth bass at ratios of 28:1 and 8:1, respectively. Showing that largemouth bass are now the dominant bass species, but not as dominant as they once were.


Largemouth bass and smallmouth bass were the first and second most sought after fish by anglers, with 36.5% and 30.4% of the angler directed effect, respectively. Regulation change in 2018 implemented a no size limit for largemouth bass and an 18-inch size limit for smallmouth bass, with a release season for smallies and a combined bag of five bass, of which only one may be a smallmouth bass.


Bluegills are the most abundant and most popular panfish species in Diamond Lake. Length at age data from previous surveys indicate slow growth. Diamond has historically had high abundances of small bluegills, but recent surveys show decreasing bluegill abundances. Angler catch rates of bluegills are also on a downward trend. The decreasing bluegill abundance in Diamond Lake could be leading to faster growth. 


Anglers who visit Diamond Lake often make a stop at Crystal Lake, just across the road to the south of Diamond. Crystal is a 117-acre lake with a maximum depth of 29 feet. There is a public boat landing on Crystal, which has a fishery that includes largemouth bass, smallmouth bass, walleyes, and northern Wisconsin’s three main panfish species. 

Diamond Lake

Nearest town: Cable

Surface area: 322 acres

Max. depth: 83 feet

Water clarity: 30 feet


Fish species present: black crappies, bluegills, pumpkinseeds, rock bass, yellow perch, white suckers, trout, smallmouth  bass, largemouth bass, northern pike, and walleyes.


For information: DNR regional fisheries office (715) 779-0436, the DNR web site, or call Loon Saloon Sports, (715) 794-2265.

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