Long Term Resource Monitoring Program

Special Report

97-S001

Comparison of Catch Between 3 × 6

and 2 × 4 Fyke Nets

on Upper Mississippi River Backwater Lakes

May 1997
LTRMP Special Reports provide Long Term Resource Monitoring Program partners

with scientific and technical support. The opinions and conclusions

in LTRMP Special Reports are those of the author(s) and do not

necessarily reflect those of the Environmental Management Technical Center.

This report did not receive anonymous peer review.

Environmental Management

Technical Center

CENTER DIRECTOR

Robert L. Delaney

MANAGEMENT APPLICATIONS AND

INTEGRATION DIRECTOR

Kenneth Lubinski

INFORMATION AND TECHNOLOGY

SERVICES DIRECTOR

Norman W. Hildrum

REPORT EDITOR

Deborah K. Harris

Cover graphic by Mi Ae Lipe-Butterbrodt

Mention of trade names or commercial products does not constitute endorsement

or recommendation for use by the U.S. Geological Survey, U.S. Department of the Interior.

Printed on recycled paper 
Comparison of Catch Between 3 × 6

and 2 × 4 Fyke Nets

on Upper Mississippi River Backwater Lakes

by

Scott A. Gritters

Iowa Department of Natural Resources

Mississippi Monitoring Station

206 Rose Street

Bellevue, Iowa 52031

Project Leader:

Randy Burkhardt

May 1997

Prepared for

U.S. Geological Survey

Environmental Management Technical Center

575 Lester Avenue

Onalaska, Wisconsin 54650

This PDF file may appear different from the printed report

because of slight variations incurred by electronic transmission.

The substance of the report remains unchanged.
Suggested citation:

Gritters, S. A. 1997. Comparison of catch between 3 × 6 and 2 × 4 fyke nets on Upper Mississippi River backwater lakes. Report

prepared for the U.S. Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, May 1997.

LTRMP 97-S001. 7 pp.

Additional copies of this report may be obtained from the National Technical Information Service, 5285 Port Royal Road,

Springfield, Virginia 22161 (1-800-553-6847 or 703-487-4650).
iii

Contents

Page

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction ........................................................................ 1

Methods ........................................................................... 1

Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Table

Table. Number of fish captured by species and relative abundance for 3 × 6 and 2 × 4 nets, Upper

Mississippi River System, Pool 13, 1989 ........................................... 4

Figures

Figure 1. Backwater lakes sampled, Upper Mississippi River System, Pool 13, 1989. ............ 5

Figure 2. Length frequency of black crappie (Pomoxis nigromaculatus) collected by length class

during 3 × 6 and 2 × 4 net comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 3. Length frequency of white crappie (Pomoxis annularis) collected during 3 × 6 and 2 × 4 net

comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 4. Length frequency of bluegill (Lepomis macrochirus) collected during 3 × 6 and 2 × 4 net

comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 5. Relative abundance of family groups in 3 × 6 and 2 × 4 fyke nets .................... 7
v

Preface

The Long Term Resource Monitoring Program (LTRMP) was authorized under the Water Resources

Development Act of 1986 (Public Law 99-662) as an element of the U.S. Army Corps of Engineers'

Environmental Management Program. The LTRMP is being implemented by the Environmental

Management Technical Center, a U.S. Geological Survey science center, in cooperation with the five Upper

Mississippi River System (UMRS) States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin. The U.S.

Army Corps of Engineers provides guidance and has overall Program responsibility. The mode of operation

and respective roles of the agencies are outlined in a 1988 Memorandum of Agreement.

The UMRS encompasses the commercially navigable reaches of the Upper Mississippi River, as well

as the Illinois River and navigable portions of the Kaskaskia, Black, St. Croix, and Minnesota Rivers.

Congress has declared the UMRS to be both a nationally significant ecosystem and a nationally significant

commercial navigation system. The mission of the LTRMP is to provide decision makers with information

for maintaining the UMRS as a sustainable large river ecosystem given its multiple-use character. The longterm goals of the Program are to understand the system, determine resource trends and effects, develop

management alternatives, manage information, and develop useful products.

This report was prepared under Task 2.2.8.5, Evaluate and Refine the Experimental Design, Strategy

2.2.8, Monitor and Evaluate Fish Communities, Guilds, and Populations, as specified in Goal 2 of the

Operating Plan of the Long Term Resource Monitoring Program for the Upper Mississippi River System

(USFWS 1993). This report was developed with funding provided by the Long Term Resource Monitoring

Program.
Comparison of Catch Between 3 × 6

and 2 × 4 Fyke Nets

on Upper Mississippi River Backwater Lakes

by

Scott A. Gritters

Abstract

The fisheries component of the Long Term Resource Monitoring Program was initiated in 1989 to acquire a

baseline database of fishes in the Upper Mississippi River System. Proper gear selection is essential for

providing valuable fisheries data to area managers. Types of gear used for assessments by fisheries managers

are subject to individual preferences. However, lack of standardization of gear types among managers may cause

confusion when comparing data sets. Two configurations of fyke nets were compared when fished in the same

habitats in 1989. A large fyke net (3 × 6) and a small fyke net (2 × 4) were used in the same backwater areas and

the catches compared. Large nets caught nearly 4.2 times more fish than the small nets. A 92% species overlap

was noted between the two net types when measured by the Sorenson coefficient. In each type of net, 24 species

of fish were collected. Species composition and abundance were similar, but not identical, in the two net types.

The fish communities collected had a similarity index of 0.83 on the Morisita's Index (Im), where 1 = identical

and 0 = no similarity. A higher percentage of sunfish species and a lower percentage of miscellaneous species

were caught in the larger net. Average lengths were not significantly different in the two nets, and length

frequencies of black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis) were nearly identical

between the two nets.

Introduction

Sampling equipment used for fisheries assessments have typically been subject to manager's preference.

Standardization of gear types has not been achieved, which often leads to confusion when examining

historical data sets. Although, fyke nets have long been used to sample fisheries resources, different fyke

net configurations have been used. Two common net sizes compared in the present study were the 3-ft by

6-ft fyke (3 × 6) and the 2-ft by 4-ft (2 × 4) fyke.

The 3 × 6 fyke net is often considered bulky to handle, and the large catches hinder prompt work-up time,

resulting in stressed fish. The 2 × 4 fyke net was tested as a potential alternative for reducing sample size

and minimizing fish mortality.

Methods

In July 1989, I compared the catch effectiveness of 3 × 6 and 2 × 4 trap nets at study sites in six backwater

lakes of the Upper Mississippi River System in Pool 13 (Figure 1). Each lake complex included two sample

sites to provide replicate data sets. Initially, a 2 × 4 or 3 × 6 fyke net was set at each replicate site for 24 h.

After 24 h, the nets were interchanged and the sites fished for another 24 h. All fish were counted and

length–weight information was taken on the principal species.

The 3 × 6 net has a 15.2-m (50-ft) lead and the 2 × 4 has a 12.2-m (40-ft) lead. Both nets have two throats

and 1.9-cm (3/4-inch) mesh. Sets were made with the lead staked on the bank–water interface, and the net

was set perpendicularly to the shoreline. In vegetated backwater habitat, the lead was staked 1.8 m (6 ft)

from the edge of the vegetation with the net stretched perpendicularly into open water.
2

Results and Discussion

Two thousand seven hundred twenty-two fishes were collected in 24 net sets. The 3 × 6 net contained

81% of the total catch (2,195 fish), with an average of 182.9 fish caught per net day. The 2 × 4 net averaged

43.9 fish caught per net day. Twenty-four species of fish were identified from both nets (Table).

T. E. McCarthy (Iowa Department of Natural Resources, personal communication), found a significant

difference in catch between the 2 × 4 and 3 × 6 nets. He used two separate years of data in the comparison,

however, and did not separate the species collected. In 1985, the 2 × 4 net averaged 67.2 fish; in 1986, the

3 × 6 net averaged 117.6 fish. Both nets were set at identical locations.

Relative abundance was similar for most species in both net types. Bluegills (Lepomis macrochirus),

black crappie (Pomoxis nigromaculatus), and white crappie (P. annularis) were the dominant fish species

collected. The large net had a higher relative abundance of bluegills. Although bluegills composed 53.3%

of the catch in the 3 × 6 net, they accounted for only 26.2% of the catch in the 2 × 4 net. Relative abundance

of black crappie and white crappie was nearly identical (Table).

I used the Morisita's Index of Community similarity (Im) to compare species composition in both net types.

This index refers to the probability that individuals of the two net types will belong to the same species,

relative to the probability of selecting a pair of specimens of the same species from one of the nets (Morisita

1959). The index can range from zero (no similarity) to 1 (identical) and is calculated from the formula:

Im = 2E(xiyi)/(I1+I2)N1N2

where x is the number of individuals of species I in the 3 × 6 net, and y is the number of individuals of i i

species I in the 2 × 4 net. N is the total number of individuals from the 3 × 6 net, and N is the total number 1 2

of individuals from the 2 × 4 net. I is calculated by the formula: 1

I = Ex (x !1)/N (N !1) 1 i i 1 1

and I is calculated from the formula: 2

I = Ey (y !1)/N (N !1). 2 i i 2 2

The composition of fish collected by the two net types was found to be similar, but not identical, with a

value of 0.83 according to Morisita's Index. The length frequencies of bluegill, black crappie, and white

crappie were similar for both net types. The average lengths of black crappie in 3 × 6 and 2 × 4 nets were

151.8 and 156.8 mm, respectively. The length frequency of black crappie correlated closely and

demonstrated two dominant year-class peaks (Figure 2). The average lengths of white crappie in the 3 × 6

and 2 × 4 nets were 185 and 197 mm, respectively. Length frequencies also correlated closely and

demonstrated several year-class peaks in both nets (Figure 3). Bluegill size structure did not correlate as

closely as did samples from crappies (Figure 4); however, the average length was similar in both net types.

Bluegills averaged 125 mm in the large nets; they averaged 131.4 mm in the smaller nets.

Centrarchids were the dominant family group in both net types, composing 88% of the 3 × 6 catch and

69.4% of the 2 × 4 catch (Figure 5). The small nets contained more Catostomids and other miscellaneous

fish than the large nets. Suckers composed 10.4% of the fish in small nets, but only 4.9% of those in the large

nets. Other families made up only 4% of the relative abundance in the large nets, but composed 17.8% of

that in the small nets. The catch of gars was similar for both nets.
3

Summary

The 3 × 6 fyke net is a more efficient capture tool than the 2 × 4 net. Large nets contained 4.2 times more

fish than small nets. Small nets can be used as an alternative in situations where large catches should be

avoided. The 3 × 6 net contained a higher percentage of sunfish (mostly bluegills) but a lower percentage

of suckers and miscellaneous fishes. The overall composition of fish in both nets was similar; both nets

produced an equal number of species with a high species overlap. There was no appreciable difference in

the size structure and average lengths of fish caught with the two nets. 

Acknowledgments

The U.S. Army Corps of Engineers provided fiscal support and management of the Environmental

Management Program. I thank the U.S. Fish and Wildlife Service, Region 3, for the administration of the

Long Term Resource Monitoring Program and the Environmental Management Technical Center for their

management of the Long Term Resource Monitoring Program and the development of sampling procedures.

I thank the Iowa Department of Natural Resources for administration of the field station budget and

operations. I am grateful for the assistance from the staff of the Iowa Department of Natural Resources, Lake

Macbride Station, for help in collecting these data. I also thank personnel of the Bellevue, Iowa, Long Term

Resource Monitoring Program Station for their assistance and logistical support in data collection and

preparation. In particular, I thank G. Ardinger, D. Harris, R. Gent, D. Gould, M. Griffin, T. McCarthy, L.

Hodge-Richardson, T. Shay, P. Sleeper, M. Steuck, and E. Tauber, without whom this project could not have

been completed.

References

Morisita, M. 1959. Measuring of interspecific association and similarity between communities. Memoirs

of the Faculty of Science, Kyushu University, Series E (Biology) 3:65–80.

U.S. Fish and Wildlife Service. 1993. Operating Plan for the Upper Mississippi River System Long Term

Resource Monitoring Program. Environmental Management Technical Center, Onalaska, Wisconsin,

Revised September 1993. EMTC 91-P002R. 179 pp. (NTIS #PB94-160199)
4

Table. Number of fish captured by species and relative abundance for 3 × 6 and 2 × 4 nets, Upper Mississippi River

System, Pool 13, 1989.

________________________________________________________________________________________________

 Relative

 Number abundance (%) 

Species 3 × 6 2 × 4 3 × 6 2 × 4

________________________________________________________________________________________________

Family Lepisosteidae:

 Longnose gar (Lepisosteus platostomus) 3 2 0.1 0.4

 Shortnose gar (L. osseus) 64 10 2.9 1.9

Family Amiidae:

 Bowfin (Amia calva) 3 3 0.1 0.6

Family Clupeidae:

 Gizzard shad (Dorosoma cepedianum) 5 17 0.2 3.2

Family Cyprinidae:

 Common carp (Cyprinus carpio) 28 39 1.3 7.4

 Golden shiner (Notemigonus crysoleucas) 14 5 0.6 0.9

Family Catostomidae:

 River carpsucker (Carpiodes carpio) 2 0 0.1 0.0

 Smallmouth buffalo (Ictiobus bubalus) 8 5 0.4 0.9

 Spotted sucker (Minytrema melanops) 47 29 2.1 5.5

 Shorthead redhorse (Moxostoma macrolepidotum) 52 21 2.4 4.0

 

Family Ictaluridae: 

 Yellow bullhead (Ameiurus natalis) 4 6 0.2 1.1

 Black bullhead (A. melas) 2 3 0.1 0.6

 Channel catfish (Ictalurus punctatus) 2 3 0.1 0.6

Family Esocidae:

 Northern pike (Esox lucius) 3 1 0.1 0.2

Family Percichthyidae:

 Yellow bass (Morone mississippiensis) 2 1 0.1 0.2

Family Centrarchidae:

 Pumpkinseed (Lepomis gibbosus) 87 28 4.0 5.3

 Warmouth (L. gulosus) 0 1 0.0 0.2

 Orangespotted sunfish (L. humilis) 0 1 0.0 0.2

 Bluegill (L. macrochirus) 1,171 138 53.3 26.2

 Largemouth bass (Micropterus salmoides) 19 2 0.9 0.4

 White crappie (Pomoxis annularis) 212 44 9.6 8.3

 Black crappie (P. nigromaculatus) 442 152 20.1 28.8

Family Percidae:

 Yellow perch (Perca flavescens) 7 3 0.3 0.6

 Sauger (Stizostedion canadense) 9 5 0.4 0.9

 Walleye (S. vitreum) 2 0 0.1 0.0

Family Sciaenidae:

 Freshwater drum (Aplodinotus grunniens) 7 8 0.3 1.5

 Total 2,195 527

________________________________________________________________________________________________
5

Figure 1. Backwater lakes sampled, Upper Mississippi River System, Pool 13, 1989.
6

Figure 2. Length frequency of black crappie (Pomoxis nigromaculatus) collected by length class

during 3 × 6 and 2 × 4 net comparisons.

Figure 3. Length frequency of white crappie (Pomoxis annularis) collected during 3 × 6 and 2 × 4 net

comparisons.
7

Figure 4. Length frequency of bluegill (Lepomis macrochirus) collected during 3 × 6 and 2 × 4 net

comparisons.

Figure 5. Relative abundance of family groups in 3 × 6 and 2 × 4 fyke nets.
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this

collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson

Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, D.C. 20503

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

May 1997

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Comparison of catch between 3 × 6 and 2 × 4 fyke nets on Upper Mississippi River backwater lakes

6. AUTHOR(S)

Scott A. Gritters

7. PERFORMING ORGANIZATION NAME AND ADDRESS 8. PERFORMING ORGANIZATION

Iowa Department of Natural Resources REPORT NUMBER

Mississippi Monitoring Station

206 Rose Street

Bellevue, Iowa 52031

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

U.S. Geological Survey 

Environmental Management Technical Center 97-S001

575 Lester Avenue

Onalaska, Wisconsin 54650

 AGENCY REPORT NUMBER

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Release unlimited. Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 

(1-800-553-6847 or 703-487-4650)

13. ABSTRACT (Maximum 200 words)

The fisheries component of the Long Term Resource Monitoring Program was initiated in 1989 to acquire a baseline database of fishes in the Upper Mississippi River System. 

Proper gear selection is essential for providing valuable fisheries data to area managers. Types of gear used for assessments by fisheries managers are subject to individual

preferences. However, lack of standardization of gear types among managers may cause confusion when comparing data sets. Two configurations of fyke nets were compared when

fished in the same habitats in 1989. A large fyke net (3 × 6) and a small fyke net (2 × 4) were used in the same backwater areas and the catches compared. Large nets caught nearly

4.2 times more fish than the small nets. A 92% species overlap was noted between the two net types when measured by the Sorenson coefficient. In each type of net, 24 species of

fish were collected. Species composition and abundance were similar, but not identical, in the two net types. The fish communities collected had a similarity index of 0.83 on the

Morisita's Index (Im), where 1 = identical and 0 = no similarity. A higher percentage of sunfish species and a lower percentage of miscellaneous species were caught in the larger net. 

Average lengths were not significantly different in the two nets, and length frequencies of black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis) were nearly

identical between the two nets.

14. SUBJECT TERMS 15. NUMBER OF PAGES

Backwater lakes, black crappie, fyke nets, Upper Mississippi River System, white crappie 7 pp.

16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

 OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclassified Unclassified
The Long Term Resource Monitoring Program (LTRMP) for the Upper Mississippi

River System was authorized under the Water Resources Development Act of 1986 as 

an element of the Environmental Management Program. The mission of the LTRMP

is to provide river managers with information for maintaining the Upper Mississippi 

River System as a sustainable large river ecosystem given its multiple-use character.

The LTRMP is a cooperative effort by the U.S. Geological Survey, the U.S. Army Corps

of Engineers, and the States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin.