Big Rivers Catfish Assessment

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Angler holds large catfish
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The Missouri Department of Conservation recently completed a multiyear assessment of blue catfish and flathead catfish in the Mississippi and Missouri rivers. Results indicate that while these fisheries are healthy and sustainable, regulation changes could improve the chances of harvesting more and/or catching larger blue catfish and flathead catfish. MDC will be reaching out to fishers to learn their preferences for managing these fisheries. A brief summary of the study results and links to the full reports can be found below.

For more information contact MDC Public Involvement Coordinator Michele Baumer at Michele.Baumer@mdc.mo.gov, or 573-751-4115, EXT 3350.

Background and Objectives

Blue catfish and flathead catfish were assessed during 2015–2018.

Primary Objectives

  • Determine catfish population demographics (sizes and ages)
  • Determine exploitation (harvest) by anglers
  • Determine if new harvest regulations may improve the quality of the population (more and larger fish)

Study Details

Population Demographics

Electrofishing was used to capture catfish; all catfish were measured, and some were weighed and aged.

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Blue Catfish

  • 6,639 captured (size range: 3-53 inches)
  • 1,874 aged (age range: 1-19 years)
Average age for blue catfish to reach various lengths and weights.
Length (inches) Weight (pounds) Age to reach size
Mississippi River Missouri River
15 1 4 5
18 2 5 6
24 5 8 9
30 10 11 12
38 20 17 18
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Flathead Catfish

Average age for flathead catfish to reach various lengths and weights.
Length (inches) Weight (pounds) Age to reach size
Mississippi River Missouri River
14 1 4 4
18 2 5 5
24 5 8 7
30 10 12 10
36 20 17 13
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In the past, the highest percentage of Missouri catfish anglers who responded to a survey considered a 20-pound blue catfish or flathead catfish to be a ‘trophy’. Catfish larger than 20 lbs. (greater than 38” for blue catfish and greater than 36” for flathead catfish) are referred to as ‘large’ below.

Exploitation and Mortality

Reward tags were affixed to some catfish to determine exploitation rates, which is the proportion of fish in a population that are being harvested. Multiple reward values were used to estimate tag reporting rates.

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Number of blue catfish tagged, number of tags reported by fishers within one year of tagging, and estimated exploitation rate.
River # Tagged # of Tags Reported Exploitation
Fish Kept Fish Release
Mississippi River 759 66 8 10%
Missouri River 915 76 21 12.7%
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Number of flathead catfish tagged, number of tags reported by fishers within one year of tagging, and estimated exploitation rate.
River # Tagged # of Tags Reported Exploitation
Fish Kept Fish Release
Mississippi River 836 61 11 10%
Missouri River 850 71 25 12%
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Harvest Regulations

Population demographics and exploitation estimates were used to determine fishery responses to a variety of potential regulation changes. On the Missouri River, sport fishing regulations allow harvest of five blue catfish and five flathead catfish daily, with no size restrictions. On the Mississippi River, sport fish regulations allow harvest of 20 blue and channel catfish in the aggregate and 10 flathead catfish daily, with no size restrictions. Commercial fishing regulations allow harvest of an unlimited number of blue catfish and flathead catfish at least 15” long from the Mississippi River and from the lower St. Francis River (that portion which forms the border between Missouri and Arkansas). Commercial catfish harvest is prohibited on the Missouri River.

The graphs below compare how yield (total weight of fish harvested) and the number of catfish greater than 20 pounds (38” for blue catfish, 36” for flathead catfish) in the population were predicted to change with an 18” MLL (minimum length limit), 21” MLL, 24” MLL, 1 over 30” (daily bag limit), or 1 over 35” (daily bag limit) regulation change. A protected slot limit (26-34”), like the blue catfish regulation at Lake of the Ozarks and Harry S. Truman Reservoir, increased the number of large catfish in the population more than with a minimum length limit, but greatly decreased yield, and was therefore considered inappropriate for Mississippi and Missouri river catfish fisheries.

Mississippi River

Blue catfish and flathead catfish yield improved with an 18” MLL but declined with all other regulations. All regulations increased the number of large catfish in the population. A 24” MLL increased the number of large catfish in the population most but would decrease yield.

Mississippi River catfish harvest chart showing yield compared to length limit.

Missouri River

All minimum length limits (MLL) increased both yield and the number of large catfish in the population for both species. However, yield declined with both “1 over” regulation changes. Blue catfish yield improved most with a 24” MLL while the number of large catfish in the population increased most with the 1 over 30” regulation. Flathead catfish yield improved most with a 21” MLL while the number of large catfish in the population increased most with a 24” MLL.

Missouri River catfish harvest chart showing yield compared to length limit.

Study Findings 

  • Our studies confirmed that current management approaches continue to support healthy and sustainable blue catfish and flathead catfish populations in the Mississippi and Missouri rivers, and regulation changes do not appear to be necessary to maintain these populations or prevent overfishing. Under current conditions, blue catfish harvest would have to triple and flathead catfish harvest would have to double before overfishing would become a concern.
  • Our studies identified opportunities to manage these fisheries to better meet the desires of fishers.
  • If fishing effort remains steady, our models indicate that a minimum length limit (MLL) could maintain or improve yield and also increase the number of large catfish in the population.