INVESTIGATIONS IN FISH CONTROL

3. Minimum Lethal Levels of Toxaphene as a Piscicide 

in North Dakota Lakes

4. Effects of Toxaphene on

Plankton and Aquatic Invertebrates 

in North Dakota Lakes

5. Growth Rates of Yellow Perch 

in Two North Dakota Lakes 

After Population Reduction with Toxaphene

6. Mortality of Some Species of Fish 

to Toxaphene at Three Temperatures

7. Treatment of East Bay, Alger County, Michigan 

with Toxaphene for Control of Sea Lampreys

8. Effects of Toxaphene on Fishes and Bottom Fauna 

of Big Kitoi Creek, Afognak Island, Alaska

United States Department of the Interior

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife
INVESTIGATIONS IN FISH CONTROL

Investigations in Fish Control, published by the Bureau of Sport Fisheries and Wildlife, include reports on the results of work at the Bureaufs Fish Control Laboratories at La Crosse, 

Wis., and Warm Springs, Ga., and reports of other studies related to that work. Though each 

report is regarded as a separate publication, several may be issued under a single cover, for 

economy.

Current reports in this series are 

(Reports 1 and 2 are in one cover,)

1. Laboratories and Methods for Screening Fish-Control Chemicals, by Robert E. Lennon and 

Charles R. Walker. (Bureau Circular 185.) 1964. 15 p.

2. Preliminary Observations on the Toxicity of Antimycin A to Fish and Other Aquatic Animals, by Charles R. Walker, Robert E. Lennon, and Bernard L. Berger. (Bureau Circular 

186.) 1964. 18 p.

(Reports 3 through 8 are in one cover,)

3. Minimum Lethal Levels of Toxaphene as a Piscicide in North Dakota Lakes, by Dale L. 

Henegar. (Resource Publication 7.) 1966.

4. Effects of Toxaphene on Plankton and Aquatic Invertebrates in North Dakota Lakes, by 

Robert G. Needham. (Resource Publication 8.) 1966.

5. Growth Rates of Yellow Perch in Two North Dakota Lakes After Population Reduction with 

Toxaphene, by Donald C. Warnick. (Resource Publication 9.) 1966.

6. Mortality of Some Species of Fish to Toxaphene at Three Temperatures, by Mahmoud 

Ahmed Mahdi. (Resource Publication 10.) 1966.

7. Treatment of East Bay, Alger County, Michigan, with Toxaphene for Control of Sea Lampreys, by William E. Gaylord and Bernard R. Smith. (Resource Publication 11.) 1966.

8. Effects of Toxaphene on Fishes and Bottom Fauna of Big Kitoi Creek, Afognak Island, 

 Alaska, by William R. Meehan and William L. Sheridan. (Resource Publication 12.) 1966.

9. Relation of Chemical Structure to Fish Toxicity in Nitrosalicylanilides and Related Compounds, by Charles R. Walker, Roland J. Starkey, and Leif L. Marking. (Resource Publication 13.) In press.

10. Evaluati9n of p,pf-DDT as a Reference Toxicant in Bioassays, by Leif L. Marking. (Resource Publication 14.) In press.

11. Evaluation of an Electronic Method of Measuring Hematocrits of Fish, by Richard A, 

Schoettger and Arnold M. Julin. (Resource Publication 15.) In press.

Fish Control Laboratories

Bureau of Sport Fisheries and Wildlife

U. S. Department of the Interior

P. O. Box 862

La Crosse, Wisconsin 54602
INVESTIGATIONS IN FISH CONTROL

3. Minimum Lethal Levels of Toxaphene as a Piscicide in 

North Dakota Lakes

By Dale L. Henegar (Resource Publication 7, p. 1-16)

4. Effects of Toxaphene on Plankton and Aquatic 

Invertebrates in North Dakota Lakes

By Robert G. Needham (Resource Publication 8, p. 1-16)

5. Growth Rates of Yellow Perch in Two North Dakota 

Lakes After Population Reduction with Toxaphene

By Donald C. Warnick (Resource Publication 9, p. 1-9)

6. Mortality of Some Species of Fish to Toxaphene at 

Three Temperatures

By Mahmoud Ahmed Mahdi (Resource Publication 10, p. 1-10)

7. Treatment of East Bay, Alger County, Michigan with 

Toxaphene for Control of Sea Lampreys

By William E. Gaylord and Bernard R. Smith 

(Resource Publication 11, p. 1-7)

8. Effects of Toxaphene on Fishes and Bottom Fauna of 

Big Kitoi Creek, Afognak Island, Alaska

By William R. Meehan and William L. Sheridan 

(Resource Publication 12, p. 1-9)

United States Department of the Interior, Stewart L. Udall, Secretary

Stanley A. Cain, Assistant Secretary for Fish and Wildlife and Parks

Fish and Wildlife Service, Clarence F. Pautzke, Commissioner

Bureau of Sport Fisheries and Wildlife, John S. Gottschalk, Director
NOTE

Toxaphene has never been registered for use as a piscicide. The Bureau 

of Sport Fisheries and Wildlife has discontinued management use of toxaphene at least until completion of definitive studies on detoxification in 

relation to water quality, residual toxicities, and short-term effects of its 

use on aquatic organisms. These six papers on toxaphene and its effects 

are published as contributions to an understanding of the chemical and its 

use in fish management.

ii
INVESTIGATIONS IN FISH CONTROL

3. Minimum Lethal Levels of Toxaphene as a Piscicide 

in North Dakota Lakes

By Dale L. Henegar

Chief, Fish Management Division

North Dakota Game and Fish Department

U.S. DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

Bureau of Sport Fisheries and Wildlife

Resource Publication 7

Washington . January 1966
CONTENTS

Page

Abstract. ........................................ 3

Characteristics of toxaphene ........................... 4

Method of application ................................ 4

Characteristics of the lakes............................ 6

Test netting. ...................................... 6

Results. ......................................... 7

Odland Lake ................................... 7

Brush Lake.................................... 8

Long Lake. .................................... 8

Gumms Lake. .................................. 9

North Lake Metigoshe............................. 9

South Lake Metigoshe ............................. 10

Red Willow Lake ................................ 11

Frettum Lake .................................. 11

North Lake Tobiason. ............................. 12

Bowbells Mine Lake .............................. 12

Glen Ullin Reservoir. ............................. 12

South Lake Tobiason.............................. 13

Nieuwsma Lake ................................. 13

Cat Coulee Lake. ................................ 13

Wolfe Butte Lake ................................ 13

Jund Lake. .................................... 14

Discussion and conclusions ............................ 14

Summary ........................................ 15

References ....................................... 15
MINIMUM LETHAL LEVELS OF TOXAPHENE AS A 

PISCICIDE IN NORTH DAKOTA LAKES

By Dale L. Henegar, Chief, Fish Management Division 

North Dakota Game and Fish Department

Abstract. To determine minimum levels of toxaphene lethal to fishes in 

prairie lakes and reservoirs, 16 North Dakota lakes, ranging from 6.3 to 

915 acres, were treated in 1959 and 1960 with concentrations of toxaphene 

ranging from 0.005 to 0.035 p.p.m. Physical and chemical studies were 

made of each area, hydrological maps were prepared, and test netting was 

carried out before and after treatment; application methods and equipment 

were according to North Dakota Game and Fish Department regulations. 

Mortality after treatment varied from incomplete, involving only youngof-the-year fish, to complete. A marked selective mortality pattern was 

noted: smaller fish succumbed at lower dosages; as the concentrations 

were increased, larger fish were killed. Duration of toxicity did not appear 

excessive five of the seven lakes in which mortality was complete were 

successfully restocked within 7 months after treatment.

Toxaphene (chlorated camphene) has not 

been widely used as a piscicide for local field 

application because minimum lethal concentrations in the field have not been determined. 

Considerable information has been gained from 

laboratory bioassay studies (Surber, 1948; 

Doudoroff et al., 1953; Hooper and Grzenda, 

1957; Henderson et al., 1959), but the concentrations indicated by such studies are not 

necessarily correct for field use. Prevost 

(1960) pointed out that results of controlled 

laboratory experiments do not always yield 

dosages giving similar results in the field, 

where there are a number of variables, both 

known and unknown, over which the field worker 

has little or no control.

Gebhards (1960) in his review lists 14 Western States and 6 Canadian Provinces that have 

used toxaphene in fish-control programs in 

various formulations at concentrations ranging

This publication is based on a thesis submitted to the 

Graduate Faculty, Department of Agriculture, South 

Dakota State College of Agriculture and Mechanic Arts, 

in partial fulfillment of the requirements for the degree 

of Master of Science, June 1961.

from a low of 0.003 parts per million (p.p.m.) 

to a high of 0.61 p.p.m. Inconsistencies were 

emphasized in the review by the side variations in results. Fifteen of the reports said an 

average concentration of 0.185 p.p.m. failed to 

kill all fishes in treated areas, while 23 reports 

mention that an average concentration of 0.139 

p.p.m. caused complete mortality. Stringer and 

McMynn (1958) reported complete kills at from 

0.010 p.p.m. to 0.036 p.p.m.

In North Dakota, mortality of fish was complete when toxaphene was applied at a concentration of 0.070 p.p.m., which was not considered the minimum lethal level (Henegar, 1958). 

It was to determine the desirable minimum 

concentration for management use in North 

Dakota that this study was initiated.

Sixteen lakes were chosen for treatment 

during 1959 and 1960. All were test netted to 

determine existing populations of fish both 

before and after treatment. Physical and chemical characteristics were studied to establish 

criteria. Application of the toxaphene followed 

procedures commonly used by the North Dakota 

Game and Fish Department.
For lakes with physical and chemical characteristics of those in the Great Plains, recommended concentrations range from 0.025 to 

0.030 p.p.m. as indicated in table 1. Concentrations used on the project areas ranged from 

0.005 to 0.035 p.p.m.

TABLE 1. Recommended concentration of toxaphene for various types of lakes. 

[William Cooper & Nephews, Chicago, 111,, 1958]

Concentration of 

toxaphene

25-30 p.p.b. 1 ... 

15-20 p.p.b..... 

10-20 p.p.b..... 

7.5-10 p.p.b....

Lake type

Unstratified, shallow, hard-water lakes of low 

transparency and high productivity.

Unstratified, soft-water lakes of moderate or high 

transparency.

Stratified lakes of moderate depth (mean depth less 

than 20 feet) and moderate to low transparency.

Stratified lakes of great depth (mean depth greater 

than 20 feet), high transparency, and low productivity.

1 One report indicates that a concentration of 50-100 p.p.b. should be 

used in highly turbid waters containing suspended clay (Secchi disk reading 

less than 1 foot).

I wish to express my appreciation to Marvin 

O. Allum, Assistant Professor of Zoology, for 

his suggestions, interest, and constructive 

criticism during this study. I also wish to thank 

Dr. Donald Progulske, Assistant Professor of 

Zoology, for his advice and suggestions on 

preparation of the manuscript. I am obliged to 

all the members of the Fishery Division of the 

North Dakota Game and Fish Department who 

generously contributed time and suggestions on 

the field work.

CHARACTERISTICS OF TOXAPHENE

Toxaphene is one of the group of toxicants 

known as cyclodione insecticides, which also 

includes aldrin, dieldrin, chlordane, heptachlor, 

endrin, and isodrin. Toxaphene is not as well 

characterized chemically as the others, and 

the precise nature of the compounds in the 

mixture of isomers is not known (Negherbon, 

1959). Most frequently encountered formulations are 10- to 20-percent dusts, 40-percent 

wettable powders, and emulsifiable concentrates of 4, 6, and 8 pounds per gallon.

The commercial product used in the study 

was Agricultural Cooper-Tox No. 6 (toxaphene 

emulsifiable concentrate) manufactured by

William Cooper & Nephews, Chicago, 111. The 

formulation contained 6 pounds of technical 

toxaphene per gallon.

Toxaphene remains toxic for extended periods of time following application as a piscicide. Ten Michigan lakes treated in 1949 and 

1950 detoxified in from 8 to 33 months. Other 

Michigan lakes detoxified in from 2 to 10 

months after being treated at a concentration 

of 0.010 p.p.m. (Hooper and Grzenda, 1957). 

Stringer and McMynn (1960) reported that 

several British Columbia lakes remained toxic 

for over 2 years after treatment. Application 

at 1.00 p.p.m. (2.7 Ibs. per acre-foot) gave 

concentrations of from 0.40 to 0.50 p.p.m. 

toxaphene.

Application rates do not appear to be important to the duration of toxicity when applied 

within the median tolerance limits of fishes. 

Mayhew (1959) stated that the period of toxicity 

is more related to chemical and physical characteristics of treated lakes than to the concentration of toxaphene.

The factors which influence detoxification 

are dilution, water temperature, water circulation, oxygen levels, turbidity, alkalinity, 

types of substrate, microorganisms, and ratio 

of water to bottom interface (Hemphill, 1954; 

Hooper and Grzenda, 1957; Rose, 1958; Henegar, 1958; Prevost, 1960).

Detoxification takes place very slowly when 

ice cover is present and more rapidly when 

water temperatures are high and conditions 

are favorable for the growth of plankton and 

other microorganisms.

METHOD OF APPLICATION

Toxaphene has been applied in various ways, 

the method usually depending on the formulation. The wettable powder has been applied by 

aircraft and by placing it in burlap bags and 

then towing in the wake of an outboard motor 

(Henegar, 1953). The emulsifiable liquid has 

been applied by aircraft, but most commonly 

by distributing premixed solutions with powder 

sprayers mounted in boats. One method is the 

metering of desired amounts into the wake of a
moving outboard-powered boat (Stringer and 

McMynn, 1960), but unless this is carefully 

controlled the toxaphene solution may settle to 

the bottom in a comparatively undiluted state.

In this study, a pumping system used by the 

North Dakota Game and Fish Department was 

employed (fig. 1). It consists of a 55-gallon 

drum connected to a motor-driven centrifugal 

pump with two outlet pipes terminating in 

common garden-type nozzles extending behind 

the boat transom on each side. During use, the 

nozzles are in contact with the surface of the 

lake to minimize airborne spray from coming 

in contact with the boat operator.

The toxaphene was premixed in the barrel at 

a maximum ratio of 1 gallon to 5 gallons of 

water so that a minimum of 55 gallons of liquid 

was available for spraying on each lake. During 

application the spray boat, powered by an 18- 

horsepower outboard motor, was operated at 

full throttle. This allowed for a maximum coverage of 200 acres an hour. On smaller lakes 

adjustment of the nozzles reduced application 

time to as little as 30 minutes.

The spray unit was left intact in the boat 

after each project, when the boat was loaded 

onto a boat trailer. This reduced the time necessary to ready equipment for each treatment.

Figure 1. Spray boat used in application of toxaphene on project lakes.
Areas for treatment were determined from 

prepared hydrographic maps of each lake. 

Lakes over 100 acres in size were subsectioned, and each subsection was treated as a 

separate unit.

CHARACTERISTICS OF THE LAKES

For study I selected 16 lakes, varying in size 

from 6.3 to 915 acres, in widely scattered 

areas of North Dakota. Seven are impoundments, and nine are natural. Maximum depths 

ranged from 8 to 26 feet, and volume from 79 

to 8,254 acre-feet (table 2). At the time of 

treatment, none of the lakes were chemically 

or thermally stratified,,

Water samples were taken from all lakes, 

and field analyses were made to determine

chemical characteristics of the water (table 2). 

Concurrently, 1-gallon samples of water were 

forwarded to the North Dakota Health Department to check the accuracy of the field analyses. The variation in results between field and 

laboratory analyses was not significant.

With one exception, all the lakes had extensive growths of aquatic vegetation extending 

from shore outward to a depth of 8 feet. 

Potamogeton spp. and Myriophyllum spp. were 

particularly abundant, with Polygonum spp. and 

Sagittaria spp. prevailing less frequently. In all 

the lakes, primary bottom composition was silt, 

mud, clay, and organic material. Areas of sand, 

gravel, and rubble were of minor importance 

and were restricted to the natural lakes.

TABLE 2. Physical and chemical characteristics of project lakes

Lake Size

Acres

103.3 

160.2 

290.8 

173.6

670.8 

915.0 

129.9 

95.2

50.3 

6.3 

12.3

40.1

80.8 

8.0 

17.3 

18.5

Maximum 

depth

Feet

19 

23 

23 

8

22 

22 

26 

22

14 

21 

18 

10

23 

17 

14 

14

Volume

Acre-feet

712.9 

1,526.7 

2,390.6 

853.7

7,588.5 

8,254.4 

1,272.8 

511.7

472.8 

78.9 

144.4 

286.9

651.2 

87.4 

137.5 

162.9

PH

8.2 

8.5 

8.3 

9.0

8.8 

8.7 

8.0 

8.3

8.6 

9.9 

8.0 

8.5

7.9 

8.8 

9.4 

8.0

Alkalinity

Phenolphthalein

120 

40 

40 

84

20 

30 

24 

54

44 

0 

60 

106

0 

30 

100 

20

Methyl 

orange

180 

460 

220 

442

210 

240 

178 

496

282

800 

420 

460

140 

130 

260 

80

Hardness

171 

476 

308 

821

205 

238 

239 

444

359 

2,385 

136

547

136 

170 

114 

51

Total 

dissolved 

solids

414 

290 

307 

816

317 

326 

364 

281

779 

4,100 

418 

1,452

415 

328 

940 

306

TEST NETTING

Qualitative sampling of fish populations in all 

lakes was carried out before and after treatment (table 3). Three types of gear were used, 

gill nets, small-mesh seines, and small-mesh 

frame nets.

The gill nets were experimental nylon nets, 

250 by 6 feet, composed of 50-foot sections of 

increasing mesh size: 3/4, 1, 1-1/4, 1-1/2, 

and 2 inches. Total netting effort for each lake 

varied according to size: a greater number of 

sets were made in larger lakes. The nets were 

fished in diurnal and nocturnal periods to lend 

validity to the results. Although this type of 

gear is subject to considerable error, estimates of fish populations may be made from

the data. During the project period all lakes 

were gill-netted a total of 2,304 hours, representing 96 individual sets.

Shoreline seining with a 100- by 6-foot, 

1/4-inch-mesh, nylon bag seine was done 

where vegetation was not too dense. Data 

so gathered were of limited value owing to

TABLE 3. Fishes in project lakes.

Rainbow trout, Salmo galrdneri Richardson. 

Northern pike, Esox lucius Linnaeus. 

Carp, Cyprlnus carpio Linnaeus.

Golden shiner, Notemigonus crysoleucas (Mitchill). 

Bluntnose minnow, Pimephales notatus (Rafinesque). 

White sucker, Catostomus commersonl (Lacepede). 

Black bullhead, Ictalurus melas (Rafinesque). 

Brown bullhead, Ictalurus nebulosus (LeSueur). 

Orangespotted sunfish, Lepomis humllls (Girard). 

Bluegill, Lepomis macrochirus Rafinesque. 

White crappie, Pomoxis annularis Rafinesque. 

Black crappie, Pomoxis nieromaculatus (LeSueur). 

Yellow perch, Perca flavescens (Mitchill). 

Walleye, Stlzostedlon vitreum vltreum (Mitchill).
inconsistent results. Altogether, 71 drags were 

made in project lakes, representing a coverage 

of 35,500 square feet.

Small-mesh frame nets produced valid data 

on populations of fishes inhabiting the littoral 

zone. These nets were originally designed to 

sample young-of-the-year northern pike in 

heavily vegetated areas. The front frame of 

each net was 3 feet high and 4 feet wide (fig. 2); 

the net was 15 feet long and had round wooden 

hoops behind the front rectangular frame. The 

webbing was 1/4-inch nylon dyed a dark brown. 

The single tunnel used the string type of construction rather than open orifice, and the net 

retained the trapped fishes very satisfactorily. 

The single, 50-foot lead from the front frame 

was of the same material as the body of the net. 

In use, the frame nets were placed at right 

angles to the shoreline. A net of this type can 

be placed in position by one man, and sets are 

made without using a boat. Representative 

catches were made in all types of habitat. The 

frame nets were fished a total of 3,704 hours 

during the project period.

RESULTS

ODLAND LAKE

1

Odland Lake was treated on August 12, 1960, 

with toxaphene at a concentration of 0.005 p.p.m. 

No effects of the toxaphene were observed for 

10 hours following application; after this period, distressed young-of-the-year yellow 

perch and black bullheads were noted in the 

shallow bays and backwaters. Within 36 hours 

many of these small fishes were either lying 

dead on the bottom or washed ashore. Evident 

mortality ceased 48 hours after application. In 

the observation period only seven larger fish 

were noticeably affected. The small fish decomposed rapidly, and after 7 days evidence of 

their mortality disappeared.

The lake was test-netted 48 days after treatment. Net frequencies (table 5) were not significantly changed from those arrived at before 

the toxaphene was used. In this lake the net 

frequencies did not show the true population

TABLE 4. Concentrations of toxaphene applied and fish mortality in project 

lakes

Lake Concentration 

(p. p.m. )

0.015

0.020

0.035

Mortality

TABLE 5. Changes in test-netting frequencies following application of 

toxaphene in project lakes

[Frequencies are computed as fish per hour per net both for frame and gill 

nets. Seining data not used]

Figure 2. Small-mesh frame net used to sample fishes 

in the littoral zone.

Concentration 

(p. p.m.)

0.005 

0.010 

0.010 

0.010 

0.015 

0.015 

0.015 

0.020 

0.020 

0.025 

0.025 

0.025 

0.025 

0.030 

0.030 

0.035

Frequency

Before 

treatment

6.91 

6.88 

10.38 

34.46 

8.46 

6.46 

10.20 

6.36 

12.91 

.95 

6.91 

7.29 

5.89 

4.06 

15.08 

3.62

After 

treatment

6.94 

1.34 

1.59 

7.96 

1.07 

1.11 

2.50 

.32 

.33 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00

Reduction 

( Percent )

None 

80.5 

84.6 

76.9 

87.3 

83.2 

75.4 

94.9 

97.4 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0
structure. Young-of-the-year fishes taken 

during pretreatment test netting (table 6) were 

absent from the data. Average sizes of larger 

fishes remained relatively stable, reflecting 

insignificant mortality.

BRUSH LAKE

Brush Lake was treated on October 5, 1959, 

with toxaphene at a concentration of 0.010 p.p.m. 

Application preceded lake freeze-up by only 2 

days. During the 2 days that observations could 

be made, no affected fish were found. The following spring (157 days after treatment) thousands of partly decomposed yellow perch (2.1 

to 6.1 inches) were washed on shore. Seventeen 

walleyes (9.8 to 12.3 inches) and five northern 

pike (10.1 to 13.1 inches) were recorded. Further observations for 5 days after breakup did 

not reveal additional current mortality.

Ninety-six hours of posttreatment test netting starting on April 22, 1960, disclosed only 

a partial mortality among the fishes. It was 

evident from the results (table 7) that although 

mortality was heavy among the young-of-theyear and older yellow perch (2.1 to 5.9 inches), 

little difference in the abundance of the larger 

fishes could be found. Total test netting frequency was reduced by 80.5 percent (table 5).

On May 27, 1960, Brush Lake was stocked 

with 29,000 northern pike fingerlings (2,000/lb.). 

On June 26, 1960, it was stocked with 48,000 

walleye fingerlings (1,600/lb.) and on August 1, 

1960, with 200,000 bluntnose minnows (1,000/lb.).

TABLE 6. Mland Lake test netting data before and after treatment with 

0.005 p.p.m. toxaphene

[Combined data from all types of netting gear]

TABLE 7. Brush Lake test netting data before and after treatment with O.C 

p.p.m. toxaphene

[Combined data from all types of netting gear]

Species

Before treatment (134 hours):

After treatment (152 hours):

Number

418 

405 

44 

27 

17 

9 

3 

2

904 

0 

59 

48 

19 

17 

11 

1

Length (inches)

Range

4.0 - 11.6 

young-of-year 

3.4 - 6.5 

5.1 - 6.5 

16.0 - 28.3 

9.0 - 18.5 

7.5 - 8.5 

5.5 - 5.6

5.0 - 10.5 

young-of-year 

15.0 - 29.0 

3.5 - 12.5 

5.5 - 9.0 

6.0 - 7.1 

5.5 - 6.0 

16.7

Average

5.8

5.5 

6.1 

21.7 

13.6 

8.0 

5.5

5.7

21.8 

5.8 

7.3 

6.5 

5.6 

17.7

£^>ecies

Before treatment (144 hours):

After treatment (96 hours):

Number

908 

894 

49 

32 

4

57 

0 

56 

39 

7

Length (inches)

Range

2.6 - 13.7 

young-of-year 

9.7 - 17.7 

10.3 - 27.2 

10.1 - 10.5

6.0 - 12.8 

young-of-year 

17.6 - 30.2 

15.8 - 18.1 

10.8 - 11.1

Average

4.1

15.6 

20.3

10.3

7.2

22.4 

16.1

10.9

Additional test netting of the lake in September proved good survival and growth of all 

stocked fishes. This test netting also substantiated results from the posttreatment survey.

LONG LAKE

Long Lake was treated on July 17, 1960, wit 

toxaphene at a concentration of 0.010 p.p.m. 

Mortality during the first 3 hours after application was light and was restricted to youngof-the-year yellow perch. At the end of 5 

hours, yearling and 2-year-old yellow perch 

were in distress. Twenty hours later yellow - 

perch up to 5.1 inches were either moribund 

or dead in all sections of the lake. At this tim 

distressed and dying young-of-the-year northern pike were found. Deaths continued until -72 

hours after treatment, when the last affected 

fish were observed. During the apparent peric 

of toxicity only two dead 10-inch walleyes and 

no northern pike larger than young-of-the-yea 

were observed. No dead white suckers could t 

located.

On August 18, approximately 1 month after 

treatment, Long Lake was stocked with 160,OC 

(360/lb.) bluntnose minnows. Periodic observe 

tions for 10 days after stocking indicated no 

mortality of these fishes.

During posttreatment test netting begun on 

October 25, the stocked minnows were frequently taken in the small-mesh frame nets. 

Yields of these small-mesh frame nets (table! 

denoted that the toxaphene had either severely 

reduced or eliminated yellow perch less than 

5.5 inches in length. Partial reduction of 

young-of-the-year northern pike was evident.
TABLE 8.--Long Lake test netting tefore and after treatment with 0.010 

p.p.m. toxaphene

[Combined data from all types of netting gear]

TABLE 9. Gumms Lake test netting before and after treatment with 0.010 

p.p.m. toxaphene

[Combined data from all types of netting gear]

Species

Before treatment (250 hours):

After treatment (250 hours):

Number

1,240 

1,017 

6 

327 

3

263 

0 

5 

114 

3 

3

Length (inches)

Range

2.6 - 6.8 

young-of-year 

26.0 - 31.3 

young-of-year 

10.0 - 10.3

5.6 - 6.8 

young-of-year 

25.1 - 32.1 

young-of-year 

10.3 - 10.6 

17.3 - 17.6

Average

3.8 

28.2 

10.1

6.5 

28.6

10.4 

17.5

Total net frequency on all fishes was reduced 

by 84.6 percent (table 5). No measurable 

changes were found in the populations of adult 

northern pike, walleyes, or white suckers 

(table 8).

GUMMS LAKE

Gumms Lake was treated on August 8, 1959, 

with toxaphene at a concentration of 0.015 

p.p.m. At time of treatment the lake contained 

the largest yellow perch population of all project lakes (table 9). One hour after application, 

small affected yellow perch were seen over 

most of the surface of the lake. After 3 hours 

many yellow perch (2.4 to 6.6 inches) were 

either distressed or dead. This condition was 

maintained for 26 hours, after which the incidence started a rapid decline. The last moribund fish was located 71 hours after treatment, 

and by this time thousands of yellow perch 

lined the shore and were floating on the lake. 

During the period of mortality no yellow perch 

larger than 7 inches were seen.

Test netting on September 14, 1958, revealed 

an incomplete kill. No yellow perch smaller 

than 5.5 inches were taken, but the abundance 

of larger yellow perch remained unchanged 

(table 9). Average size of fishes taken during 

this posttreatment netting increased from 5.3 

to 7.8 inches (table 9). Total net frequency 

indicated a gross reduction of 87.3 percent 

(table 5).

Plans for additional test netting of this lake 

in 1960 were abandoned after winter-kill conditions during the winter of 1959-60.

Species

Before treatment (28 hours):

After treatment (28 hours):

Number

964 

223

Length (inches)

flange

3.1 - 10.2 

7.0 - 10.3

Average

5.3 

7.8

NORTH LAKE METIGOSHE

North Lake Metigoshe was treated on September 13, 1960, with toxaphene at a concentration of 0.015 p.p.m. It was the second 

largest lake in the project and contained the 

most desirable fish population. Because of its 

size, it was treated in segments, and each was 

sprayed as a separate unit. Application was 

completed in 6 hours.

Reaction of the fishes to the toxaphene was 

slow because of low water temperature of 43 

F., but by the end of 14 hours following completion of treatment surfacing of small fishes 

was noted. Young-of-the-year yellow perch 

and black bullheads were affected first, followed by larger perch (2.0 to 3.2 inches) and 

bullheads (2.2 to 5.8 inches) after 20 hours. 

Thirty-six hours later, numbers of dead and 

affected perch and bullheads were blown to 

the north shore by a strong southerly wind that 

prevailed for 10 hours. Frequency of distressed 

fishes was highest after 72 hours, after which 

there was a rapid decline. All activity had 

ceased at the end of 12 days.

Observations of gross mortality after 96 

hours disclosed countless yellow perch ranging 

from young-of-the-year to 5.1 inches in length, 

181 northern pike (11.9 to 18.4 inches), and 17 

walleyes (14.2 to 15.2 inches). No mortality of 

white suckers was noted. Observers checking 

the bays and shallow water failed to find any 

living bullheads or yellow perch.

Posttreatment netting was delayed to 3 days 

before freeze-up (October 24). Observations 

made on the lake during the period of toxicity 

were confirmed by the results of the test netting (table 10). The toxaphene had failed to kill 

all fishes in the lake (fig. 3). Yellow perch
TABLE 10. North Lake Metigoshe test netting data before and after treatment 

with 0.015 p.p.m. toxaphene

[Combined data from all types of netting gear]

Species

Before treatment (322 hours):

After treatment (322 hours):

Number

1,305 

626 

416 

1,438 

46 

27 

17 

9

49 

0 

246 

0 

39 

15 

8

Length (inches)

Range

2.4 - 10.1 

young-of-year 

2.1 - 11.1 

young-of-year 

13.0 - 25.3 

12.0 - 24.8

17.7 - 23.0

4.3 - 9.6 

young-of-year 

6.1 - 10.2 

young-of-year 

19.1 - 26.2 

13.3 - 24.7 

17.6 - 24.0

Average

4.1 

4.8

17.6 

16.1

19.9

6.8 

7.6

22.8 

19.3 

19.8

Figure 3. Fish taken in gill net from North Lake 

Metigoshe after treatment with 0.015 p.p.m. toxaphene.

from young-of-the-year to 4.0 inches and black 

bullheads from young-of-the-year to 5.8 inches 

were absent from the nets. The average sizes 

of yellow perch and black bullheads increased 

from 4.1 inches to 6.8 inches and 4.8 inches to 

7.6 inches respectively (table 10). Average 

sizes of northern pike, walleyes, and white

suckers stayed approximately the same. Reduction in total test net frequency was 87.3 

percent (table 5).

SOUTH LAKE METIGOSHE

South Lake Metigoshe was treated on July 7, 

1960, with toxaphene at a concentration of 0.01J 

p.p.m. It was the largest lake in the project anc 

for convenience was divided into segments for 

treatment. Application of the toxaphene was 

completed in 7 hours.

High water temperature (75° F.) at time of 

treatment caused the toxaphene to act rapidly 

on the fishes. One hour after starting application small yellow perch and black bullheads 

were surfacing. Frequency of distress increased rapidly, and at the end of 2 hours 

moribund and dead fishes were seen in treated 

areas (fig. 4). Rate of death increased in all 

parts of the lake for another 48 hours and then 

began a rapid decrease. Ninety-six hours later

Figure 4. Moribund and dead young-of-the-year yellow 

perch taken at South Lake Metigoshe 4 hours after 

treatment with 0.015 p.p.m. of toxaphene.

10
major activity had stopped. Ten days later a 

discontinuation of activity was obvious.

Five to 7 days after treatment, "float-up" 

took place as thousands of decomposing fish 

floated into shore. This caused a publicrelations problem of some magnitude with the 

491 cabin owners on the lake and emphasized 

the value of fall treatment. Mortality estimates made at the time were of questionable 

value because fishes were picked up and disposed of as soon as they came to shore. It 

seemed, however, that while many smaller 

fishes had succumbed, the larger fishes were 

unaffected.

Posttreatment test netting (table 11) from 

September 17 to 20 proved the kill was incomplete. Young-of-the-year yellow perch, black 

bullheads, and northern pike were severely 

reduced. The only area containing any of these 

fishes was close to the entrance from North 

Lake Metigoshe. It is probable that they migrated into the area from this entrance following detoxification.

Yellow perch (2.4 to 4.0 inches) and black 

bullheads (2.1 to 4.2 inches) were absent from 

the population samples taken after treatment. 

Frequencies and average sizes of the northern 

pike, walleyes, and white suckers in the posttreatment population were relatively the same 

as before treatment. Total test netting frequency was reduced by 83.2 percent (table 5).

ting, some sport fishing took place. A small 

number of both fishes were taken until fishing 

was halted by freeze-up.

RED WILLOW LAKE

Red Willow Lake was treated on July 17, 

1959, with toxaphene at a concentration of 

0.020 p.p.m. During application the water temperature was 72° F., and action of the toxicant 

was rapid. Small yellow perch and black bullheads surfaced 1 hour after spraying was begun. 

Surfacing movements became more rapid and 

then waned at the end of 72 hours. Many yellow 

perch (3.1 to 6.8 inches) and black bullheads 

(3.2 to 5.6 inches) were discovered in the vegetation and along the shore. Observations also 

disclosed 73 dead northern pike (12.4 to 17.6 

inches) and only 2 dead white suckers (17.2 

inches).

Test netting of the lake on October 13, 1959, 

(table 12) disclosed an incomplete kill of the 

fish population. The reduction of yellow perch 

was of consequence, but the black bullheads 

retained their original abundance. Average 

length of the yellow perch increased from 5.3 

to 6.9 inches, while the average length of the 

black bullheads increased only from 6.8 to 6.9 

inches. Frequencies of larger fishes failed to 

display a positive reduction. Total net frequency was lowered by 75.4 percent (table 5).

After the presence of walleyes and northern 

pike was established by the posttreatment netTABLE 11. South Lake Metigoshe test netting data before 

with 0.015 p.p.m. toxaphene

nd after treatment

[Combined data from all types of netting gear]

Northern pike 

Do.........

Walleye......

2,984

2,024

737

814

18

142

104

17

520

26

19

28

22

Length (inches)

Range

2.4 - 9.5 

young-of-year

2.1 - 9.7 

young-of-year

10.7 - 21.7 

young-of-year

7.5 - 25.5

4.1 - 9.4 

young-of-year

4.2 - 9.6 

young-of-year

14.1 - 22.3 

young-of-year

12.1 - 24.2

Average

18.1

6.1

18.3

20.1

9.1

18.6

FRETTUM LAKE

Frettum Lake was treated on July 19, 1959, 

with toxaphene at a concentration of 0.020 

p.p.m. Pretreatment test netting of this lake

TABLE 12. Red Willow Lake test netting data before and after treatment with 

0.015 p.p.m. toxaphene

[Combined data from all types of netting gear]

Species

Before treatment (48 hours ) : 

Yellow perch

After treatment (48 hours ) :

Number

351 

120 

12 

7

5 

103 

13 

2

Lenj'th (inches)

Range

3.7 - 

3.8 - 

13.0 -

14.0 -

6.6 - 

3.9 -

9.0 - 

14.9 -

7.1 

9.0 

27.5 

18.5

7.2 

8.2

16.7 

15.0

Average

5.3 

6.8 

19.9

17.4

6.9 

6.9

14.7 

14.9

11
revealed a dense population of yellow perch 

except for young-of-the-year. In only 3 hours 

after application, numerous fishes were either 

dead or distressed. After 96 hours further 

movement could not be found. This initial high 

mortality of the perch suggested the possibility 

of a complete kill. Posttreatment test netting 

on October 21, 1959, proved this assumption to 

be incorrect. Although smaller yellow perch 

(4.0 to 6.4 inches) were absent from the test 

nets, larger yellow perch were taken (table 13). 

The average length of the yellow perch increased from 5.3 to 7.3 inches, and percent 

reduction of total netting frequency was 94.9 

(table 5).

TABLE 13. Frettum Lake test netting data before and after treatment with 

0.020 p.p.m. toxaphene

[Combined data from all types of netting gear]

TABLE 14. North Lake Tobiason test netting data before and after treatment 

with 0.020 p.p.m. toxaphene

[Combined data from all types of netting gear]

Species

Before treatment (120 hours):

After treatment (116 hours):

Number

429 

335

38 

0

Length (inches)

Range

4.1 - 14.0 

young-of-year

6.5 - 14.1 

young-of-year

Average

5.3 

7.3

NORTH LAKE TOBIASON

North Lake Tobiason was treated on August 

6, 1959, with toxaphene at a concentration of 

0.020 p.p.m. Reaction of fishes to the toxaphene 

began 1 hour after spraying was started, and 

after 4 hours yellow perch and brown bullheads 

were surfacing over the entire lake. This activity gained in intensity for another 68 hours 

and then dwindled to nothing after 72 hours. 

When apparent toxicity ceased, examination of 

the dead fish revealed many dead yellow perch 

and brown bullheads but only five dead northern 

pike (19.2 to 20.5 inches).

This lake was not test netted until 10 months 

after treatment (June 7, 1960), and results 

ascertained that only a partial kill had taken 

place. Brown bullheads were absent from the 

test nets. No yellow perch were taken in the 

samples, and the only fishes surviving were 

larger northern pike and white suckers (table 

14). The percent reduction in total net frequency was 97.4 (table 5).

Species

Before treatment (48 hours):

After treatment (48 hours):

Number

446 

160 

5 

6

4

0 

8 

7

Length (inches)

Range

3.1 - 7.2 

4.2 - 10.2 

19.1 - 26.2 

16.4 - 19.0 

4.3 - 4.5

16.5 - 19.0 

21.0 - 26.1

Average

5.3 

7.8 

23.7 

17.2 

4.4

17.3 

24.2

BOWBELLS MINE LAKE

Bowbells Mine Lake was treated on August 

28, 1959, with toxaphene at a concentration of 

0.025 p.p.m. The lake, which was the smallest 

of the series involved, manifested extremes in 

water chemistry (table 2). The origin of the 

lake is seepage of ground water into an abandoned lignite-coal strip mine. The toxicant 

acted more slowly on the fishes than in any 

other project lake, and 6 hours elapsed before 

the first distressed yellow perch were visible. 

The frequency of kill increased gradually for 

96 hours after which it dropped off rapidly, and 

at the end of 10 days a cessation of activity war 

noted.

Posttreatment test netting (table 15) was not 

carried out until May 9, 1960, at which time no 

fish were taken. The lake was then restocked 

on September 21, 1960, with 2,200 rainbow 

trout (2.8/lb.). Test netting in November 1960 

disclosed good survival and additional growth 

of the trout.

GLEN ULLIN RESERVOIR

Glen Ullin Reservoir was treated on July 23,

1959. with toxaphene at a concentration of 

0.025 p.p.m. Fishes reacted rapidly to the 

toxicant, and within 4 hours after spraying was 

begun distressed fish were in evidence in all 

areas of the lake. After 17 hours, mortality of 

white crappie and yellow perch appeared complete. No carp or white suckers were observed 

until 14 hours after treatment, but all had 

apparently died after 35 hours. Continued observations for 7 days disclosed no further 

mortality. Two days of posttreatment test 

netting on September 26, 1959, and May 17,

1960. did not yield any live fish (table 16). The

12
TABLE 15. Bowbells Mine Lake test netting data before and after treatment 

with 0.025 p.p.m. toxaphene

[Combined data fron all types of netting gear]

Species

Before treatment (24 hours):

After treatment (48 hours):

Number

17 

6

Length (inches)

Range

5.1 - 8.3 

12.2 - 17.1

Average

7.2 

14.2

TABLE 17. South Lake Tobiason test netting before and after treatment with 

0.025 p.p.m. toxaphene

[Combined data from all types of netting gear]

Species

Before treatment (24 hours):

After treatment (96 hours):

Number

172 

2

1

Length (inches)

Range

5.5 - 6.9 

12.0 

6.2

Average

6.2 

12.0 

6.2

TABLE 16. Glen Ullin Reservoir test netting data before and after treatment 

with 0.025 p.p.m. toxaphene

[Combined data fron all types of netting gear]

Species

Before treatment (24 hours):

After treatment (48 hours):

Number

160 

3 

2

1

Length (inches)

Range

3.1 - 5.0 

4.7 - 5.2 

13.1 - 13.4 

13.0

Average

4.5 

5.0 

13.25 

13.0

lake was then restocked with 5,000 fingerling 

largemouth bass, 572 adult white crappies, 

90,000 bluntnose minnows, and 7,500 fingerling bluegills. Subsequent test netting in November 1960 indicated good survival and 

growth of these fishes.

SOUTH LAKE TOBIASON

South Lake Tobiason was treated on August 

7, 1959, with toxaphene at a concentration of 

0.025 p.p.m. Six hours after treatment, large 

numbers of distressed or dead black bullheads 

were found around the shore or floating on the 

surface. Forty-eight hours later no further 

mortality was apparent.

Posttreatment test netting on October 9, 

1959, and April 12, 1960, failed to take any live 

fishes (table 17).

NIEUWSMA LAKE

Nieuwsma Lake had been treated in 1957 with 

emulsifiable rotenone at a concentration of 1.00 

p.p.m. The treatment was unsuccessful in killing all of the black bullheads. Plantings of 

northern pike and bluegills in 1958 were of 

limited value. Retreatment of the lake with a 

concentration of 0.025 p.p.m. of toxaphene was

carried out on June 7, 1960. Five hours after 

beginning the application, large numbers of 

black bullheads could be seen at the surface. 

Mortality continued for 120 hours and then 

dwindled until after 145 hours no further movement was observed.

On October 2, 1960, posttreatment test netting failed to produce any live fish from the 

lake (table 18).

CAT COULEE LAKE

Cat Coulee Lake had been previously treated 

twice (1.00 p.p.m. and 2.00 p.p.m. of emulsifiable rotenone) to eradicate a population of 

black bullheads. Both applications were unsuccessful. On July 15, 1959, the lake was retreated with toxaphene at a concentration of 

0.030 p.p.m. Within 5 hours of starting the 

application, distressed black bullheads were to 

be found in all areas of the lake. The few rainbow trout in the lake succumbed quickly, and 

the last moribund bullhead was observed 96 

hours later.

No fish were caught in test netting (table 19) 

on May 4, 1960. The lake was restocked on 

September 23, 1960, with 4,600 rainbow trout 

(600/lb.).

WOLF BUTTE LAKE

In 1957 Wolf Butte Lake was treated with 

1.00 p.p.m. of emulsifiable rotenone to remove 

a population of bullheads and green sunfish. 

The application was unsuccessful. Rainbow 

trout that had been stocked into the area after 

treatment furnished angling for one season, and

13
TABLE 18. Nieuwsma Lake test netting before and after treatment with 0.025 

p.p.m. toxaphene

[Combined data from all types of netting gear]

Before treatment (48 hours):

After treatment (72 hours):

Length (inc

Range

23 71

hes)

Average

TABLE 20. Wolf Butte Lake test netting data befor 

with 0.030 p.p.m. toxaphene

nd after treatment

[Combined data from all types of netting gear]

Before treatment (72 hours):

After treatment (72 hours):

18

Length (in

Range

hes)

Average

13.1

TABLE 19. Cat Coulee Lake test netting data before and after treatment 

with 0.030 p.p.m. toxaphene

[Combined data from all types of netting gear]

TABLE 21. Jund Lake test netting data before and after treatment with 0.025 

p.p.m. toxaphene

[Combined data from all types of netting gear]

Before treatment (48 hours):

After treatment (48 hours):

194

Length (inc

Range

hes)

Average

the green sunfish and bullheads quickly regained their original abundance. After this the 

trout fishing began a rapid decline.

The lake was retreated on July 9, 1960, with 

toxaphene at a concentration of 0.030 p.p.m. 

The fish reacted slowly to the toxaphene, and it 

was not until 21 hours after treatment that any 

activity was noted. Surfacing of distressed and 

dying fishes continued for 7 days, and then no 

further activity was observed.

Posttreatment test netting carried out on 

September 8, 1960, indicated all fish had succumbed (table 20).

Species

Before treatment (48 hours):

After treatment (48 hours):

Length (in

Range

shes)

Average

4.8

15.7

DISCUSSION AND CONCLUSIONS [

The mortality pattern following application 

of various concentrations of toxaphene was 

consistent, and a marked size selectivity was 

exhibited. As concentration rates were increased, the extent of mortality of larger 

fishes increased until the minimum lethal 

level (when all fishes succumbed) was reached. 

From results on the 16 project lakes it appears 

that the minimum lethal concentration for 

treatment of most North Dakota lakes is 0.025 

p.p.m. of toxaphene. Concentrations progressively less than this induce mortality only on 

progressively smaller fishes.

JUND LAKE

Jund Lake was treated on June 9, 1960, with 

toxaphene at a concentration of 0.035 p.p.m. 

Action of the toxicant was rapid, and within 2 

hours many dead small bullheads were in evidence. Activity increased for 24 hours and then 

declined at a rapid rate. After 72 hours no additional mortality was found.

On October 5, 1960, the lake was test netted, 

and negative results indicated complete mortality (table 21).

The use of sublethal dosages of toxaphene 

for partial population removal is indicated. In 

all lakes treated below lethal concentrations, 

smaller fishes were removed leaving the 

larger fishes relatively unharmed. In lakes 

without rough fish populations this removal of 

small, undesirable fishes could have beneficial 

effects on the resulting fishery. The need for 

further research along this line is pointed out.

Present methods of applying toxaphene are 

satisfactory, for during the project period no 

difficulty was experienced. Observed mortality 

patterns indicate advantages to spending more

14
than the minimum time necessary for application. This would be of greater importance if 

toxaphene were being used for partial population removal. More thorough distribution of the 

toxaphene would give more homogeneous immediate concentration, negating the problem of 

mortality among the desirable larger fishes 

from high initial unmixed concentrations. It is 

also conceivable that in larger lake (500 acres 

or more), under conditions of rapid detoxification, the concentration of toxaphene could be 

lowered to less than the minimum lethal level 

before complete mixing.

No marked correlation between water chemistry and rate of reaction of fishes to toxaphene 

was noted. It did appear that in highly alkaline 

waters the toxicant acted somewhat slower, but 

inasmuch as all lakes were alkaline in nature 

this was not definite. Temperature was the factor determining the rate of reaction: the lower 

the temperature of the water the slower the 

reaction of the fishes to the toxaphene. Results 

from Brush Lake prove that toxaphene will detoxify even while the lake is under ice cover.

Actual detoxification rates were not studied 

during the project period. It must be assumed 

that in lakes where kills were incomplete the 

initial concentration was below minimum lethal 

level or detoxification at these low dosages is 

more rapid than heretofore believed.

Five of the seven lakes in which mortality 

was complete were restocked within 7 months 

of treatment, and good survival and growth has 

been noted among the stocked fishes.

In all lakes, increase in transparency was 

evident following application of the toxaphene. 

This could have been related to the removal of 

fishes that kept materials in suspension. In 

some cases, however, it was more probable 

that the increase in transparency was due to 

limited flocculation caused by the toxaphene or 

its solvents.

No ill effects were felt by personnel working 

with the toxaphene. It appears that if toxaphene 

is judiciously handled, there is little danger in 

its use. It was found advantageous, however, to 

direct the spray downward to reduce airborne 

spray which is irritating to the eyes.

SUMMARY

During the summers of 1959 and 1960, 16 

North Dakota lakes ranging from 6.3 to 915 

acres were treated with toxaphene to remove 

populations of fishes. Objective of the study 

was to determine the minimum lethal concentration of toxaphene necessary for lake eradication projects.

Concentrations of toxaphene used on the 

lakes varied from 0.005 p.p.m. to 0.035 p.p.m. 

Incomplete mortality of fishes resulted in lakes 

at concentrations less than 0.025 p.p.m. At 

concentrations of 0.025 p.p.m. to 0.035 p.p.m. 

complete mortality was indicated, subject to 

the validity of test netting results.

Duration of toxicity of the toxaphene was not 

excessive. Five of the seven lakes in which 

kills were complete were successfully restocked within 7 months after treatment.

Results indicate that the North Dakota Game 

and Fish Department can use toxaphene at concentrations of 0.025 p.p.m. to 0.035 p.p.m. 

with reasonable assurance of killing all fishes 

in the treated lakes.

All lakes displayed a definite mortality pattern; the small fishes were the first to die, and 

the largest fishes were last. At the lowest 

project dosage of 0.005 p.p.m. only young-ofthe-year were affected. The use of toxaphene 

as a size selective piscicide is strongly suggested.

REFERENCES

Doudoroff, P., B. G. Anderson, G. E. Burdick, P. S. 

Galtsoff, W. B. Hart, R. Patrick, E. R. Strong, E. W. 

Surber, and W. M. Van Horn.

1951. Bioassay methods for the evaluation of acute 

toxicity of industrial wastes to fish. Sewage and 

Industrial Wastes, vol. 23, No. 11, p. 1380-1397.

Gebhards, Stacy V.

1960. A review of toxaphene for use in fish eradication. Idaho Department of Fish and Game. 14 p.

Hemphill, Jack E.

1954. Toxaphene as a fish toxin. Progressive FishCulturist, vol. 16, No. 1, p. 41-42.

15
Henderson, C., Q. H. Pickering, and C. M. Tarzwell. 

1959. Relative toxicity of ten chlorinated hydrocarbons 

to four species of fish. Transactions of the American Fisheries Society, vol. 88, No. 1, p. 23-32.

Henegar, Dale L.

1953. James River Eradication Project F-W-l-D-1. 

North Dakota Game and Fish Department. 23 p.

1958. A summary of eight years of chemical fish control in North Dakota. North Dakota Game and Fish 

Department. 7 p.

Hooper, Frank F., and Alfred R. Grzenda.

1957. The use of toxaphene as a fish poison. Transactions of the American Fisheries Society, vol. 85 

(1955), p. 180-190.

May hew, J.

1959. The use of toxaphene as a fish poison in strip 

mine ponds with varying physical and chemical characteristics. Proceedings of the Iowa Academy of 

Science, vol. 66, p. 512-517.

Negherbon, William O.

1959. Handbook of toxicology. Vol. 3, Insecticides, 

W. B. Saunders Co., Philadelphia. 854 p.

Prevost, G.

1960. Use of fish toxicants in the Province of Quebec 

Canadian Fish Culturist, vol. 28, p. 13-35.

Rose, E.

1958. Further notes on toxaphene in fish population 

control. Iowa State Conservation Commission, Quar 

terly Biological Report, vol. 10, No. 2.

Stringer, George E.t and Robert G. McMynn.

1958. Experiments with toxaphene as a fish poison. 

Canadian Fish Culturist, vol. 23, p. 39-47.

1960. Three year's use of toxaphene as a fish toxicar 

in British Columbia. Canadian Fish Culturist, vcl. 

28, p. 37-44.

Surber, Eugene W.

1948. Chemical control agents and their effects on 

fish. Progressive Fish Culturist, vol. 10, No. 3, 

p. 125-131.

16
/NVEST/GAT/ONS IN FISH CONTROL

4. Effects of Toxaphene on

Plankton and Aquatic Invertebrates 

in North Dakota Lakes

By Robert G. Needham, Fishery Biologist 

Montana Department of Fish and Game

U.S. DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

Bureau of Sport Fisheries and Wildlife

Resource Publication 8

Washington . January 1966
CONTENTS

Page 

Abstract......................................... 3

Methods ......................................... 4

Wolf Butte Reservoir ................................ 5

Raleigh Reservoir .................................. 7

South Lake Metigoshe ................................ 9

Odland Reservoir................................... 11

Experiments ...................................... 13

Discussion ....................................... 15

Summary ........................................ 16

References ....................................... 16
EFFECTS OF TOXAPHENE ON PLANKTON AND AQUATIC 

INVERTEBRATES IN NORTH DAKOTA LAKES

By Robert G. Needham, Fishery Biologist 

Montana Department of Fish and Game

Abstract. Effects of low concentrations of toxaphene on plankton and 

larger invertebrates were studied in four North Dakota lakes (a fifth lake, 

untreated, was a control). Brachionus, Keratella, Trichocerca, Asplanchna, 

Polyarthra, Conochiloides, Daphnia, Ceriodaphnia, Bosmina, and Cyclops 

were dominant zooplankters; none exhibited marked reduction after treatment at 5 to 34 p.p.b. Most phytoplankter populations showed no obvious 

changes after treatment, except Aphanizomenon, which increased in all 

lakes. The posttreatment increase in South Lake Metigoshe was especially 

noticeable, since there was no increase in untreated North Lake Metigoshe. 

Several of the plant-inhabiting and bottom fauna decreased slightly after 

treatment, but this did not appear to be the result of toxaphene treatment. 

Tolerance levels for several zooplankters and other aquatic invertebrates 

were observed in controlled experiments. Rotifera was the most tolerant 

group, followed in order by CladoceraandCopepoda. Among larger invertebrates, Hirudinea, Hydracarina, and Gastropoda were the most 

tolerant, followed in order by Trichoptera, Odonata, Hemiptera, 

Ephemeroptera, Amphipoda, and Coleoptera.

Use of toxicants in fishery management has 

provided considerable information concerning 

the effects of various poisons on fish. Much less 

is known of the effects on the fish-food organisms several workers have reported some 

such effects: Hooper and Grzenda, 1957, in 

Michigan; Hoffman and Olive, 1961, and Gushing and Olive, 1957, in Colorado; and Stringer 

and McMynn, 1958, in British Columbia.

The object of this study was to determine the 

effects of toxaphene at low concentrations on 

the plankton and certain other aquatic organisms under natural and controlled conditions. 

This was made possible by the rough-fish removal program in North Dakota, which various 

concentrations of toxaphene were used. InvestiThis publication is based on a thesis submitted to the 

Graduate Faculty, Montana State College, in partial fulfillment of the requirements for the degree of Master of 

Science in Fish and Wildlife Management, March 1962.

gations were carried out in four lakes a 

natural lake in the north-central part of the 

State and three impoundments in the southwest. 

A fifth lake, untreated, was a control. The study 

extended from June through September of both 

1960 and 1961.

Dr. C. J. D. Brown directed the study; Dale 

L. Henegar, Chief of Fisheries, North Dakota 

Game and Fish Department, suggested the 

problem; I am indebted also to Dr. John C. 

Wright and Dr. G. W. Prescott for help in 

identifying plankton, to Dr. George F. Edmunds, 

Jr., for help in identifying aquatic insects, to 

Donald C. Warnick for help in field work, and 

to my wife Avis for help in analysing samples. 

Chemical analyses were made by the State 

Laboratories. The fish studies were by the 

North Dakota Fish and Game Department, which 

also provided financial aid under Dingell-Johnson Projects F-2-R 7 and 9. The National Wildlife Federation granted a fellowship for the last 

year of the study.
METHODS

Surface water temperatures were obtained 

with a pocket thermometer, and depth temperatures with a reversing thermometer. Secchi 

disk readings were taken at all stations in conjunction with each collection series.

The toxaphene used was an emulsified concentrate containing 6 pounds of technical toxaphene per gallon. Before application the toxa- . 

phene was diluted to 10 to 15 times with water 

to facilitate uniform distribution. It was applied 

to the water surface by spraying from a boat.

Water samples were collected before and 

after toxaphene treatment in 1960, and once in 

1961. A summary of the physical and chemical 

data is presented in table 1.

Plankton samples were secured with a pump 

at 1.5 and 7.5 feet at all stations. All samples 

were taken while the boat was moving in order 

to avoid resampling the same water. Each 

sample contained 40 gallons of water, and two 

samples constituted a collection. Each sample 

was concentrated to 200 cc. with a No. 20 silk 

plankton net. Plankton counts consisted in total 

enumeration of all organisms in 1 cc., with the 

exception of a few abundant phytoplankters, 

which were counted by the differential method, 

employing 20 to 80 fields within a 1-cc. sample.

Plant-inhabiting organisms were collected 

with a metal device that I designed. This had an 

opening of 1 square foot and a height of 30 

inches. Openings (4 by 6 inches) were cut on 

two sides to allow for drainage; these were 

covered by screen having 30 meshes per inch. 

A sliding plate was installed at the bottom to 

sever the plants near their roots. Samples were 

limited to water depths of 2 feet or less, since 

this device had to be operated manually. Approximately 4.5 pounds (drained weight, 2-3 

minutes) of plants were taken per sample in 

1960. In 1961 this was reduced to approximately 

12 ounces, since analyses showed this to be adequate. The number of square feet of bottom 

covered in each sample varied from 8 to 16 in 

1960 and from 3 to 5 in 1961.

Bottom organisms were taken with an Ekman 

dredge at depths ranging from 4 to 10 feet. 

Either 3 or 4 square feet were sampled at each 

station. Organisms from both plant and bottom 

samples were concentrated with a screen having 30 meshes per inch.

Plant-inhabiting organisms and bottom fauna 

were sampled at the same stations, which were 

approximately 50 feet in diameter. These stations had both abundant vegetation and open 

water.

TABLE 1. Physical and chemical data before and after toxaphene treatment for two lakes 

[All chemical data except pH are expressed as parts per million; bottom temperatures i

and three reservoirs in North Dako 

re taken at depths of 9-12 feet]

Sampling dates

Wolfe Butte Reservoir (treated Aug. 8, 1960):

Raleigh Reservoir (treated Aug. 4, 1960):

South Lake Metigoshe (treated July 17, 1960):

North Lake Metigoshe (untreated control) :

Odland Reservoir (treated Aug. 11, 1960):

Temperature (°F)

Surface

71.4 

68.6 

64.0 

71.0

72.1 

71.7 

68.0 

71.0

71.8 

72.0 

64.6 

60.2 

68.5

71.8 

72.3 

64.9

69.1 

68.0 

65.0 

71.2

Bottom

68.2 

68.2 

63.7 

70.0

70.5 

68.8 

67.6 

68.2

68.5 

68.4 

62.3 

59.1 

66.8

66.8 

68.0 

61.9

66.1 

65.8 

64.0 

68.0

Secchi 

disk 

(feet)

4.9 

4.2 

7.9 

4.3

3.2 

4.7 

8.7 

11.0

7.9 

8.4 

8.3 

6.4 

10.0

8.5 

8.8 

6.4

2.2

1.8 

3.1 

2.1

Total 

solids

904 

1,025

678

266 

336

380

270 

279

299

281 

282

414 

510

574

Total 

hardness

114 

114

84

184 

196

180

228

222

208

232 

226

184 

202

208

pH

9.4 

9.1

9.2

8.4 

8.7

9.8

8.8 

8.5

9.4

8.6 

8.2

8.2 

8.2

8.5

Total 

alkalinity

408 

463

336

153 

143

200

224 

214

216

224 

214

187 

195

196

Chlorides

none 

none

trace

none 

none

28

none 

none

28

none 

none

none 

none

trace

Sulfates

280 

348

164

86 

96

143

27 

53

44

33 

53

165 

186

259

Iron

1.5 

1.1

1.0

1.0 

0.5

0.5

0.2 

0.3

0.8

0.9 

0.2

0.2 

0.8

0.5
WOLF BUTTE RESERVOIR

DESCRIPTION

Wolf Butte Reservoir, in southwestern North 

Dakota, has a surface area of 24 acres and a 

maximum depth of 9 feet. It has no permanent 

inlet or outlet, and water is supplied mainly by 

runoff. The bottom is muck. No marked thermal 

stratification was present. The area surrounding the reservoir is primarily rangeland. 

Aquatic vegetation was very abundant at all 

depths less than 4 feet. Potamogeton pectinatus, 

P. richardsoni, and Myriophyllum exalbescens, 

were the dominant plants. A heavy mat of filamentous algae (Rhizoclonium) accompanied 

these plants at the water surface.

TREATMENT

Fish. Toxaphene was applied at 35 p.p.b. on 

August 8, 1960, in an attempt to eradicate the 

fish population. This impoundment was heavily 

populated with green sunfish (Lepomis cyanellus) black bullheads (Ictalurus melas), and a 

few large rainbow trout (Salmo gairdneri). Many 

green sunfish and black bullheads were found 

dead and dying after treatment. The reservoir 

was test-netted 1 week after eradication and 

again the following spring. Two 125-foot experimental gill nets were set for 24 hours, and 

no fish of any species were taken. The reservoir was test-netted again in August of 1961, 

when one 125-foot gill net and one frame net 

were set for 24 hours. The nets contained approximately 475 black bullheads and 83 trout. 

Many young-of-the-year green sunfish were 

also observed. A trapping program later in the 

fall revealed several adult green sunfish.

Plankton. Four collections of plankton were 

made at one station near the center of the 

reservoir. Collections were made 3 days before 

treatment, and after treatment at 8 days, 30 

days, and 366 days. The kinds and numbers of 

plankton are given for each collection in table 2. 

These are arranged in a phylogenetic order 

with the zooplankters first.

Comparison in numbers per liter was made 

between pretreatment and posttreatment collections. Rotifers were represented by nine 

genera, Keratella and Asplanchna being the

TABLE 2. Number of plankters per liter in Wolf Butte Reservoir before and 

after toxaphene treatment at 35 parts per billion.

[Treated Aug. 8, 1960]

Organism

Brachionus . .

Keratella. . .

Trichocerca.

Chromogaster

Asplanchna. .

Polyarthra.'. 

Filinia.....

Hexarthra. ..

Simooephalus

Ceriodaphnia

Bosmina. ....

Chydorus . . .

Diaptomus . .

Naupliii . . .

Pandorina..

Oedogonium.

Cladophora.

Hhizoclonium

Pediastrum.

Coelastrum.

Oocystis . . .

Closteriops

Tetraedon. .

Scenedesmus

Mougeotia. .

Spirogyra. .

Closterium.

Cosmarium. .

Staurastrum

Desmidium. .

Botryococcu 

Diatoma. . . .

Navicula. . .

Pinnularia.

Pleurosigma

Cymbella. . .

Nitzschia. .

Camplyodiscu

Ceratium. . . .

Synechocysti

Polycystis . .

Merismopedia

Coelospharium

Lyngbya......

Anabaena. ....

Aphanizomenon

Nodularia....

Before

Aug. 5, 1960

1

91

__.

1

1

73

7

1

3

244

4

98

1

6

46

106

3

3

4

12

1

1

7

1

1

4

3

65

2

5

1

1

11

1

5

90,067

242

50

8

61

7,377

Aug. 16, 1960

4

15

- 

..

2

106

13

1

21

18

9

130

3

26

15

4

1

5

3

4

1

14

1

4

1

3

84

3

1

6

tr

9

2

589,405

131

28

2

58

33,157

12

After

Sept. 7, 1960

_

2

__

..

1

 1

3

129

1

18

18

11

10

8

3

7

1

52

1

2

7

2

1

1

4

149,306

2

1

1

9

1

54,716

1

Aug. 9, 1961

3

1

1

2

1

28

25

2

13

73

2 tr

1

61

3

tr

tr

tr

7 

2

tr

11

82,563

110

_

138

1 Includes nauplii of both Diaptonms and Cyclops.

2 Less than 1 per liter.

most numerous. Keratella changed from 91 before treatment to 15 at 1 week, 2 at 1 month, 

and only 1 at 1 year after treatment. Asplanchna 

increased from 73 before treatment to 106 at 1 

week after treatment, but none were present in 

collections at 1 month or 1 year after treatment. Other rotifers were too scarce for comparisons.

Cladocerans were the most abundant zooplankters, with Daphnia and Bosmina appearing 

in large numbers. Daphnia decreased from 244 

before treatment to 18 at 1 week, then increased 

to 129 at 1 month after treatment. Bosmina exhibited the reverse effect, and both were less 

abundant at 1 year after treatment. Copepoda 

were represented by Diaptomus, Cyclops, and 

undetermined nauplii. Six Diaptomus were taken 

before treatment, but none were found at 1 week 

or 1 month after treatment and only 2 at 1 year.
Cyclops decreased from 46 in the pretreatment 

collection to 3 at 1 week after treatment, but 

increased to 11 at 1 month. Nauplii decreased 

from 106 before treatment to 26 and 10 at 1 

week and 1 month after treatment. Cyclops and 

nauplii were relatively abundant the following 

year.

There were 16 genera of Chlorophyta, 8 of 

Chrysophyta, and 1 of Pyrrophyta in the collections. None exhibited numerical changes 

which could be attributed to toxaphene treatment. Eight genera of Cyanophyta were present, 

and these were the most numerous algae. 

Synechocystis and Aphanizomenon were the 

most abundant genera. Synechocystis increased 

from 90,067 before treatment to 589,405 at 1 

week after treatment, then decreased to 149,306 

at 1 month. Aphanizomenon increased from 

7,377 before treatment to 54,716 at 1 month 

after treatment. Polycystis, Coelospharium, 

and Anabaena decreased after treatment. Polycystis was abundant at 1 year, but Coelospharium and Anabaena did not reappear 1 year after 

treatment.

Most of the changes before and after treatment were small and could well be the result 

of normal fluctuations in the population or the 

result of sampling techniques. A few of these 

changes may have resulted from the toxaphene, 

but none were obvious.

Plant-inhabiting organisms. Aquatic-plantinhabiting organisms were collected at two stations on the same dates plankton was sampled. 

The numbers of organisms per pound of vegetation for the four collections is presented in 

table 3. Nineteen genera were represented, but 

only seven were numerous. Gammarus varied 

throughout the study, but remained abundant. 

Callibaetis, Caenis, and Ischnura decreased at 

1 week and 1 month after treatment, but were 

more abundant at 1 year. Tendipes decreased 

from 44 before treatment to 9 at 1 week after 

treatment, while 48 were taken at 1 month and 

25 at 1 year after treatment. Gastropoda (Physa 

and Gyraulus) increased from 771 before treatment to 1,107 at 1 week, 1,366 at 1 month, and 

1,558 at 1 year after treatment.

TABLE 3. Number of plant-inhabiting organisms and bottom fauna in Wolf 

Butte Reservoir before and after toxaphene treatment at 35 parts per 

billion.

[Plant-inhabiting organisms are expressed as the number per pound of plants 

and bottom fauna as the number per square foot of bottom. Treated Aug. 8, 

1960. tr = less than 1 per pound or per square foot]

Organism

Oligoohaeta. . .

Amphipoda : 

Oammarus ..... 

Hydracarina: 

Hydaohnidae.. 

Ephemeroptera: 

Callibaetis..

Odonata:

Hemiptera: 

Plea

Notonecta. . . .

Coleoptera: 

Haliplus..... 

Copelatus . . . .

Triohoptera:

Diptera: 

Tendipes. ... 

Probezzia . . .

Gastropoda

Peleoypoda 

Pisidium. ...

Before 

Aug. 5, 1960

Plant

63 

5

5 

6

tr 

40

1 

3

2 

tr

44 

tr

123 

648

Bottom

tr

6

1 

3

5

1

28 

3

1

2

tr

3

After

Aug. 16, 1960

Plant

172 

tr

tr

1

tr 

tr 

10

tr 

tr

9

325 

782

Bottom

tr

tr

tr 

tr

1

tr

12 

2

1

1 

1

1

Sept. 7, 1960

Plant

-

73 

2

3

tr

tr

1

48

156

1,210

Bottom

tr

44

tr 

4

9

3 

9

8

Aug. 9, 1961

Plant

-

265 

23

124 

16

3 

56

10 

2

1 

2 

tr

25

886 

672

Bottom

3

tr

tr 

tr

tr

25

6

1

4

Numerical comparisons of the seven dominant genera revealed no marked changes before 

and after treatment. Reductions of Ephemeroptera and Odonata in the first two posttreatment 

collections may be significant but could have 

resulted from an emergence.

Bottom fauna. These organisms were collected at the same stations as those used for 

plant-inhabiting organisms. Each collection 

consisted of 3 square feet of bottom. The number of organisms per square foot of bottom is 

given for each collection (table 3). Thirteen 

genera were taken, but only Gammarus and 

Tendipes were abundant. Gammarus fluctuated 

from 6 before treatment to less than 1 at 1 

week, 44 at 1 month, and less than 1 at 1 year 

after treatment. The large number at 1 month 

after treatment resulted from a collection that 

contained considerable vegetation. Tendipes decreased from 28 before treatment to 12 and 9 at 

1 week and 1 month after treatment but increased to 25 at 1 year. A comparison of the 

number of bottom organisms before and after 

treatment revealed no marked changes.
RALEIGH RESERVOIR

DESCRIPTION

Raleigh Reservoir, in southwestern North 

Dakota, has a surface area of 15 acres and a 

maximum depth of 18 feet. There are no permanent inlets or outlets, and the water is supplied 

mainly by runoff. The bottom is muck, covered 

by silt in some areas. No marked thermal 

stratification was present. The surrounding 

area is almost entirely rangeland. Aquatic 

vegetation was very abundant at all depths less 

than 3 feet. Potamogeton pectinatus, _P. richardsoni, Myriophyllum exalbescens, and Ceratophyllum demersum were the dominant plants. 

Large amounts of filamentous algae (Rhizoclonium) accompanied these plants in most 

areas.

TREATMENT

Toxaphene was applied at 25 p.p.b. on August 

4, 1960, in an attempt to remove the entire fish 

population. A complete kill was not achieved 

and a second treatment was made at 90 p.p.b. 

on September 26, 1960.

Fish. Before treatment, two 125-foot experimental gill nets and four frame nets were 

set for 24 hours. The frame nets contained several thousand golden shiners (Notemigonus 

crysoleucas), approximately 5,000 green sunfish, and 1,200 white crappies (Pomoxis annularis) and black crappies (Pomoxis nigromaculatus). The two experimental gill nets captured 

13 white suckers (Catostomus commersoni), 

11 black bullheads, and a few golden shiners, 

green sunfish, and crappies. Large numbers of 

the four most numerous species were found 

dead and dying after treatment. The reservoir 

was netted again 1 week after the first treatment, but with only two experimental gill nets 

set for 24 hours. These contained 10 white 

suckers and 5 black bullheads. Test-netting was 

discontinued since drought had lowered water 

levels to a point where restocking was impracticable.

Plankton. Four collections were made at 

one station near the center of the reservoir. 

Collections were made 1 day before the first 

treatment and at 11, 33, and 371 days after the

first treatment; a second treatment was made 

53 days after the first, and the fourth collection 

was 318 days after this treatment. Quantities of 

plankters in pretreatment and posttreatment 

collections are shown in table 4. Rotifers were 

represented by 15 genera, but only Brachionus 

and Asplanchna were abundant. Brachionus decreased from 114 before treatment to 108 at 11 

days and 15 at 33 days after treatment. Asplanchna varied from 24 before treatment to 

194 at 11 days and 16 at 33 days after treatment. Only 3 Brachionus and 1 Asplanchna were

TABLE 4.-- Number of plankton per liter in Raleigh Reservoir before and after 

treatment at 25 parts per billion.

[Treated Aug. 4, and Sept. 26, 1960]

Organism

Brachionus . .

Keratella. . .

Platyias....

Monostyla. . .

Trichocerca.

Chromogaster

Asplanchna. 

Polyarthra. .

Synohaeta . . .

Filinia.....

Testudinella

Trochosphaera

Hexarthra...

Conoohiloide

Daphnia.....

Ceriodaphnia

Bosmina. ....

Chydorus....

Diaptoraus. . .

Cyclops.....

Nauplii3 ....

Elatothrix. .

Micro spora..

Oedogonium. .

Rhizoclonium

Golenkinia..

Pediastrum. .

Coelastrum. .

Oocystis ....

Chodatella. .

Closteriopsi

Tetraedon. . .

Scenedesmus .

Crucigenia. .

Tetrastrum. .

Mougeotia.. .

Zygnema. ....

Spirogyra...

Closterium. .

Cosmarium. . .

Staurastrum.

Desmidium. . .

Botryococcus

Melosira. . . .

Diatoma. ....

Synedra. ....

Navicula. .. .

Pinnularia. .

Frustulia . . .

Ctyrosigma. . .

Pleurosigma.

Gomphonema . .

Cymbella. . . .

Nitzschia. . .

Cymatopleura

Canrplyodiscu

Ceratium. . . .

Synechocysti

Polycystis. .

Merismopedia

Coelospharium

Lyngbya.....

Anabaena. . . .

Aphanizomenon

Nodularia. . . .

Before

Aug. 3, 1960

114

13

2 tr 

tr

1

5

1

24

3

1

tr

1

tr

2

3

65

'314 44

4

10

120

190

9

7

151

7

69

4

18

11

727

17

1

2

20

4

925

5

4

8

4

6

1

tr

tr

4

8

2

2

24

54, 161

2,906

9

2

10

5

6

77

Aug. 15, 1960

108

11

17 

2

1

3

194

15

11

1

11

173

156

283

17

1

9

85

1

3

5

3

462

594

75

15

462

89

3,038

264

3

1

4

4

9

1,189

8

9

3

1

tr

tr

--

1

4

14

1

7

6,275

859

7

25

1

4

190

3,633

After

Sept. 6, 1960

15

9

1

16

7

13

tr

1

57

100

50

1

1

41

19

1

3

1

3

3

2

1

133

4

1

19

2

5

4

7

3

1

1

1

1

7

4

2,312

38

1

94

8

16

81,902

21

Aug. 10, 19611

3

7

5

tr

1

1

1

tr

9

1

8

7

1

3

1

107

tr

1

2

1

3

8

5

601,057

99

4

1

2

tr3

1 After the second treatment at 90 p.p.b.

2 Less than 1 per liter.

3 Includes nauplii of both Diaptomus and Cyelo
taken 371 days after treatment. All rotifers 

were very scarce at this time, and 6 of the 

original genera were not found.

Cladocera was the most abundant zooplankter. 

Daphnia, Ceriodaphnia, and Bosmina were 

present in large numbers. Daphnia varied from 

65 before treatment to 173 at 11 days, 57 at 33 

days, and only 9 at 371 days after treatment. 

Ceriodaphnia increased from 44 before treatment to 156 at 11 days, then decreased to 100 

at 33 days, and only 1 was taken at 371 days 

after treatment. Bosmina decreased from 314 

before treatment to 283 at 11 days and 50 at 33 

days after treatment and disappeared by 371 

days. A few Chydorus were found in the pretreatment and early posttreatment collections, 

but did not occur in the collection 371 days after 

treatment. Copepoda were represented by the 

young and adults of Diaptomus and Cyclops. 

Diaptomus changed from 10 before treatment to 

1 at 11 days and 1 at 33 days, but none at 371 

days after treatment. There were 120 Cyclops 

before treatment while collections after treatment showed 9 at 11 days, 41 at 33 days, and 8 

at 371 days. Nauplii decreased from 190 before 

treatment to 85 at 11 days, 19 at 33 days, and 7 

at 371 days after treatment.

The Chlorophyta were represented by 21 

genera. Pediastrum, Coelastrum, Closteriopsis, 

Tetraedon, Scenedesmus, Crucigenia, and Desmidium were the most abundant. All of these 

increased in the collection 11 days after treatment but were greatly reduced at 33 days and 

371 days. Spirogyra was the most abundant of 

the Chlorophyta in the collection 371 days after 

treatment, but was scarce in the pretreatment 

and early posttreatment collections. The 

Chrysophyta contained 9 genera and the Pyrrophyta 1. These were infrequently encountered, 

and no comparisons were made. The Cyanophyta 

were represented by 8 genera. Synechocystis, 

Polycystis, Coelospharium, Aphanizomenon, 

and Nodularia were the dominant organisms. 

Synechocystis and Polycystis decreased in the 

first two posttreatment collections but were 

abundant at 371 days after treatment. Coelospharium and Aphanizomenon increased after 

treatment but were scarce at 371 days after 

treatment. Nodularia varied from 77 before 

treatment to 3,663 at 11 days, 21 at 33 days, 

and 3 at 371 days after treatment.

Changes after the first treatment (25 p.p.b.) 

are probably the result of normal population 

fluctuations. At 371 days after treatment wat^i 

levels had dropped approximately 6 feet, the 

water was clear, and aquatic vegetation had increased. The severe reduction in nearly all 

plankters at this time may have been due to rh< 

drop in water levels or the possible consequen 

increased toxaphene concentration.

Plant-inhabiting organisms. Collections 

were made at two stations on the same dates 

plankton was collected. The number of organisms per pound of vegetation is presented for 

each collection (table 5). Nineteen genera were 

taken, but only eight were abundant. Gammarui 

increased from 31 before treatment to 313 at 1 

days, 569 at 33 days, and 334 at 371 days after 

treatment. Hydrachnidae decreased from 45 be 

fore treatment to 27 at 11 days, 22 at 33 dayr, 

and 14 at 371 days after treatment. Callibaet's 

Caenis, Ischnura, and Tendipes were markedly 

reduced in the first two posttreatment collections, but all except Caenis were abundant at 

371 days after treatment. Sigara decreased 

from 39 before treatment to less than 1 at 11 

days after treatment, and none were taken afte

TABLE 5. Numbers of plant inhabiting organisms and bottom fauna in Raleigh 

Reservoir before and after toxaphene treatment at 25 parts per billion.

[Plant inhabiting organisms are expressed as the number per pound of plan+.s 

and bottom fauna as the number per square foot of bottom. Treated Aug. 4, 

and Sept. 26, I960.]

Organism

Oligoohaeta... 

Hirudlnea..... 

Anphipoda: 

Gammarus . . . , . 

Hydracarina: 

Hydrachnidae. 

Ephemeroptera: 

Calllbaetis..

Odonata:

Aeschna.. ... 

Ischnura. . . .

Hemiptera : 

Notonecta . . .

Coleoptera 

Copelatus ...

Diptera:

Tendipes . .. . 

Probezzla ...

Gastropoda

Pelecypoda 

Pisidium. ...

Before 

Aug. 3, 1960

Plant

2 tr 

31 

45

66

185

tr 

109

2 

39

2

12

tr

5 

1,163

Bottom

4 

4

1 

6

2 

2

1 

27

tr 

tr

After

Aug. 15, 1960

Plant

tr 

313 

27

9

10

1

tr 

21

tr 

tr

tr 

7

tr 

tr 

tr

13 

1,695

Bottom

8

tr

tr 

tr

1

2

i, 

4

Sept. 6, 1960

Plant

569 

22

tr 

6

tr

8

tr

6

1

6 

398

Bottom

11 

3

6

tr

2

7

Aug. 10, 19IH1

Plant

5 

334 

14

60 

3

17 

1 

1 

134

5 

8

52

22 

38

Bottom

28

1

71

1 After the second treatment at 90 p.p.b.

2 Less than one per pound or square foot.

8
this time. There were 1,163 Gyraulus before 

treatment, 1,695 at 11 days, 398 at 33 days, and 

38 at 371 days after treatment.

Several changes were noted following treatment, some of which may be the result of the 

toxaphene. Reductions of Callibaetis. Caenis. 

Ischnura, and Tendipes may be significant; all 

but Caenis, however, were abundant 371 days 

after treatment. Stringer and McMynn (1958) 

reported that Ephemeroptera were killed at 30 

p.p.b. toxaphene. The disappearance of Sigara 

after treatment appears to be the result of the 

toxaphene since they exhibited low tolerance 

levels in the controlled experiments (table 11). 

The reduction of Gyraulus at 371 days after 

treatment may be related to lowered water 

levels, since other workers (Hooper and 

Grzenda, 1957; and Stringer and McMynn, 1958) 

found Gastropoda to be unaffected by toxaphene 

at 100 p.p.b.

Bottom fauna. Four collections were made 

at two stations on the same dates plant-inhabiting organisms were collected. The number 

per square foot of bottom is given for each collection (table 5). Eleven genera were taken, but 

most of these were too scarce for comparisons. 

Oligochaeta increased throughout the study from 

4 before treatment to 28 at 371 days after treatment. Gushing and Olive (1957) found an increase in Oligochaeta after treatment with 100 

p.p.b. toxaphene. Ephemeroptera decreased 

from 7 before treatment to less than 1 at 11 

days, and none were taken in succeeding collections. Tendipes decreased from 27 before 

treatment to 2 at 11 days and 6 at 33 days after 

treatment, then increased to 71 at 371 days 

after treatment.

The reductions of Ephemeroptera and 

Tendipes may be significant. Stringer and 

McMynn (1958) reported that Ephemeroptera 

were killed at 30 p.p.b. of toxaphene, and Gushing and Olive found that a concentration of 100 

p.p.b. eliminated Tendipedidae.

SOUTH LAKE METIGOSHE

DESCRIPTION

South Lake Metigoshe is a glacial lake in the 

Turtle Mountains in north central North Dakota.

It has an area of 915 surface acres and an 

average depth of 9 feet. Water is supplied 

mainly by runoff. Water levels fluctuate slightly 

owing to releases from an upstream reservoir. 

The major bottom materials are peat and muck. 

No marked thermal stratification was present. 

Trees border most of the shoreline. Aquatic 

vegetation was common and was exceptionally 

abundant in the bays. Scirpus sp. occupied several large areas near shore. Myriophyllum 

exalbescens and Ceratophyllum demersum were 

present at most depths less than 15 feet. Other 

dominant plants were Potamogeton natans, 

J?. pectinatus, P. richardsoni, P. zosteriformis, 

Najas flexilis, "Sagittaria latifolia, Eleocharis 

palustris, and Polygonum amphibium.

TREATMENT

Toxaphene was applied at 10 p.p.b. on July 17, 

1960, in an attempt to reduce the number of 

yellow perch (Perca flavescens) and black bullheads. This was supplemented by 5 p.p.b. on 

July 19.

Fish. Several 250-foot experimental gill 

nets and frame nets (0.5-inch and 0.25-inch 

mesh) were set at selected stations 1 week before, 1 week after, and again 11 months after 

treatment; the netting efforts were 333, 290, 

and 120 hours, respectively. The fish taken are 

expressed as the number per 100 net-hours. 

Adult yellow perch were reduced from 900 before treatment to 36 at 1 week and none at 11 

months after treatment. Young-of-the-year 

were reduced from 610 before treatment to 6 

at 1 week and none at 1 year after treatment. 

Young-of-the-year black bullheads decreased 

from 240 before treatment to 9 at 1 week and 

none at 11 months after treatment. Young-ofthe-year northern pike (Exos lucius) decreased 

from 40 before treatment to 10 at 1 week and 

none at 11 months after treatment. Netting at 1 

week after treatment did not show a reduction 

in adult black bullhead, northern pike, and walleye (Stizostedion vitreum), but several were 

found dead along shore at this time. No walleye 

were taken at 11 months after treatment, and 

bullheads and northern pike were greatly reduced. The paucity of all species taken at 11 

months after treatment may have been due to 

the residual effects of the toxaphene.
Plankton. Five collections were made at 

four stations on South Lake Metigoshe. These 

were made 2 days before treatment and at 4, 

40, 60, and 367 days after treatment. The pretreatment and the first two posttreatment collections at South Lake Metigoshe are compared 

with those made at four stations on North Lake 

Metigoshe, which was sampled on the same

dates. North Lake Metigoshe is adjacent to 

South Lake Metigoshe and is connected by a 

channel approximately 30 feet wide; it was not 

treated until later in the fall and could therefore be used as a control. The number of 

plankton per liter for all collections in both 

lakes is given in table 6.

TABLE 6. Number of plankton per liter in South and North Lake Metigoshe before and after toxaphene treatment at 15 parts per billion

[South Lake Metigoshe treated July 17, I960]

Organism

Before, 

July 15, 1960 July 21, 1960

North

Aug. 26, 1960

Sept. 15, 1960, 

South

Brachionus........................................

Keratella.........................................

Lecane............................................

Monostyla......................................... 3

Triohooeroa....................................... 234

Ascomorpha........................................ 1

Chromogast'er......................................

Asplanchiia........................................ 28

Polyarthra........................................ 4

Synohaeta......................................... 17

Filinia........................................... 3

Testudinella......................................

Hexarthra......................................... 11

Conochiloides..................................... 182

Stephanooeros.....................................

Daphnia........................................... 1

Simocephalus...................................... 1

Ceriodaphnia...................................... 37

Bosmina........................................... 110

Graptolebris......................................

Chydorus.......................................... 10

Diaptoraus......................................... 1

Cyclops........................................... 17

Nauplii2 .......................................... 29

Pandorina.........................................

Volvox............................................

Apiocystis........................................

Oedogonium........................................

Hhizoclonium...................................... tr

Pediastrum........................................ 4

Coelastrum........................................ tr

Oocystis..........................................

Chodatella........................................

Closteriopsis.....................................

Kirohneriella.....................................

Tetraedon.........................................

Scenedesmus.......................................

Crucigenia........................................

Mougeotia.........................................

Spirogyra.........................................

Closterium........................................

Cosmarium.........................................

Staurastrum.......................................

Desmidium.........................................

Botryococcus......................................

Dinobryon......................................... 7

Melosira.......................................... 11

Diatoma...........................................

Fragilaria........................................ 144

Synedra........................................... 42

Asterionella.........................'............. 1

Navicula.......................................... 13

Pinnularia........................................ 4

Frustulia......................................... 1

Gyrosigma......................................... tr

Pleurosigma....................................... tr

Gontphonema........................................ 2

Cymbella.......................................... 4

Nitzschia......................................... 2

Cymatopleura......................................

Camplyodiscus.....................................

Glenodinium....................................... tr

Ceratium.......................................... 52

Polyoystis........................................ 87

Merismopedia......................................

Coelospharium..................................... 7

Phormidium........................................ 3

Lyngbya........................................... 13

Anabaena.......................................... 7,794

Aphanizomenon..................................... 2,642

Nodularia......................................... 3

Gloeotrichia......................................

Ill 

3

2

3

27

235

51

1

42

396

24

3,540

5,773

1

48

2 

83

5- 

tr 

24 

35 

19 

25

15

160

1

2

67

119

4

17

1

1

tr 

tr

2 

tr

1 

tr

1

tr 

1

1

71

73

9

4

21

1,982

1,096

14

3

6

1

4

tr 

2

61 

330

tr 

238

27

1,915

1,836

871

304

tr

25

5

1

1

39

10

7

190

155

150

1

2,312

130,515

69,617

6,869

2

3 

23

3

tr

tr

1,040

50

62

1 

1

tr 

9

2

3

tr 

1 

1

300 

1,057

2,510

2,932

4,716

4,742

4

462

1

71

581

1

3

1

tr 

61

1

3

1

1

260

218

470 

tr 

81

127,470

98,018

5,019

1

1 Represents less than one per liter.

2 Includes nauplii of Djaptomus and Cyelo

10
Rotifers were represented by 15 genera. 

Trichocerca and Conochiloides were the most 

abundant. Trichocerca decreased from 234 before treatment to 31 at 40 days, 3 at 60 days, 

and 3 at 367 days after treatment. Conochiloides 

decreased from 182 before treatment to 160 at 

1 days, 1 at 40 days, none at 60 days, and less 

:han 1 at 367 days after treatment. Asplanchna 

decreased from 28 before treatment to 1 at 40 

days, none at 60 days, and 20 at 367 days after 

treatment. Hexarthra decreased from 11 before treatment to none at 40 days, none at 60 

days, and less than 1 at 367 days after treatment. Keratella, Polyarthra, and Filinia remained almost constant. There were six genera 

of Cladocera; Daphnia, Ceriodaphnia, and 

Bosmina were the most abundant. Daphnia increased from 1 before treatment to 41 at 367 

days after treatment; Ceriodaphnia remained 

nearly constant, but was less abundant at 367 

days after treatment; Bosmina decreased from 

110 before treatment to 8 at 40 days and 1 at 

367 days after treatment. Copepoda was an 

abundant group, represented by Diaptomus, 

Cyclops, and their nauplii, which remained 

nearly constant during the study.

There were 20 genera of Chlorophyta, 2 of 

Pyrrophyta, and 17 of Chrysophyta. Staurastrum. 

Ceratium. Melosira, Fragilaria, and Synedra 

were the dominant organisms in these groups. 

After treatment these increased at 40 days 

after treatment and, with the exception of 

Melosira, were more abundant at 367 days after 

treatment. Cyanophyta were the most abundant 

phytoplanters. Polycystis, Coelospharium, 

Lyngbya, Anabaena, Aphanizomenon, and 

Nodularia were abundant. Polycystis and 

Coelospharium increased slightly after treatment, whereas Anabaena, Lyngbya, Aphanizomenon, and Nodularia exhibited large posttreatment increases (table 6).

Comparisons of zooplankters before and after 

treatment revealed no marked changes. Posttreatment decreases in South Lake Metigoshe 

were not significant, because comparisons with 

untreated North Lake Metigoshe revealed similar decreases in most instances during the 

same period. Most of the dominant phytoplankters remained almost constant or increased following treatment. The large posttreatment increase exhibited by Anabaena, 

Aphanizomenon, and Nodularia may be the result of treatment, since they did not increase 

significantly in North Lake Metigoshe.

Plant-inhabiting organisms. Four stations 

were established on South Lake Metigoshe and 

five collections were made at each of these. 

Collections were made 1 day before treatment, 

and at 5, 45, 59, and 367 days after treatment. 

The pretreatment and the first two posttreatment collections at South Lake Metigoshe are 

compared with three collections made at four 

stations on North Lake Metigoshe, which were 

not treated until later in the fall. The number of 

organisms per pound of plants is given for both 

South and North Lake Metigoshe (table 7, p. 12). 

There were 28 genera of organisms taken; 

Gammarus, Tendipes, Physa, and Gyraulus were 

the most abundant. A comparison of pretreatment and posttreatment collections revealed no 

marked changes in the number of any organism.

Bottom fauna. No pretreatment samples 

were obtained, but two posttreatment samples 

were taken, which consisted of 3 square feet 

each. Tendipes was the dominant organism, but 

a few Gammarus, Chaoborus, and Oligochaeta 

were also present. Nine Tendipes per square 

foot were taken at 60 days and 31 at 367 days 

after treatment.

ODLAND RESERVOIR

DESCRIPTION

Odland Reservoir, in southwestern North 

Dakota, has a surface area of 100 acres and a 

maximum depth of 16 feet. There are no permanent inlets or outlets, and the water is supplied 

mainly by runoff. The major bottom material is 

muck. No marked thermal stratification was 

present. Aquatic vegetation was abundant in all 

shallow areas. Potamogeton pectinatus, 

P. richardsoni. Scirpus sp., Myriophyllum 

exalbescens, and Chara sp. were the dominant 

plants.

11
TABLE 7. Number of plairt-lnhablting organisms and bottom fauna in South and North Lake Metigoshe before and after toxaphene.treatment at 15 parts per billion.

[Plant inhabiting organisms expressed as the number per pound of plants and bottom fauna as number per square foot of bottom.

South Lake Metigoshe treated July 17, I960]

Organism

Amphipoda:

Hydracarina:

Ephemeroptera :

Odonata:

Hemiptera:

Trichoptera:

Coleoptera:

Diptera:

Gastropoda:

Before, 

July 16, 1960

South

1 

639 

11

2 

1

tr 

tr

tr 

tr

tr 

tr

1 

1 

3 

tr

2

1

tr 

9 

tr

24

47

North

1 tr 

198 

4

tr 

3

tr 

tr

1 

tr

tr

1 

1 

1 

tr

2 

2 

tr

5

1

28 

tr 

56 

tr

After

July 22, 1960

South

tr 

406 

5

2

tr 

tr

tr

tr 

tr 

tr

1 

tr

tr

1 

3 

tr

21

24 

tr

North

tr 

186 

4

tr 

2

tr 

1 

tr

tr

1 

1 

tr 

tr

3

2

6

tr

27 

tr 

44

Aug. 31, 1960

South

1 

177 

1

tr 

tr

tr

tr 

tr 

tr

11 

tr

31

51 

tr

North

tr 

130

1

1 

2

tr 

7

2

tr 

tr

tr

3

2

tr 

3

19 

105

Sept. 16, 1960, 

South

1 

295

1 

tr

tr 

tr

tr 

tr

1 

tr 

tr

2

29 

tr 

86 

tr

July 18, 1961, 

South

2 

424 

1 

6

1 

1 

2

7 

3

6 

tr 

tr

11 

2 

2

1

66

10

1 Represents less than 1 per pound.

TREATMENT

Fish. Toxaphene was applied at 5 p.p.b. on 

August 11, 1960, to reduce young-of-the-year 

black bullheads and yellow perch. Large numbers of these fish and several young-of-theyear northern pike, white crappie, and orangespotted sunfish (Lepomis humilis) were found 

dead along shore the day after treatment. Adults 

of these species were not significantly reduced 

by treatment, since only a few were found dead 

and large numbers were taken in posttreatment 

test nettings.

Plankton. Four collections were made at 

each of two stations. These were made 1 day 

before treatment, and at 7, 28, and 362 days 

after treatment. The kinds and number of 

plankters per liter are given for each collection (table 8). There were 10 genera of Rotifera 

taken; Brachionus. Keratella. Polyarthra, and 

Conochiloides were the most abundant and remained nearly constant before and after treatment. Cladocera were the most abundant zooplankters with Daphnia, Ceriodaphnia. and

Bosmina being most common. There were 22 

Daphnia before treatment, 68 at 7 days, 40 at 

28 days and 3 at 362 days after treatment. 

Ceriodaphnia varied from 31 before treatment 

to 66 at 7 days, 37 at 28 days, and only 1 at 362 

days after treatment. Bosmina decreased from 

459 before treatment to 24 at 28 days and 66 at 

362 days after treatment. Copepoda were 

represented by adults and nauplii of Diaptomus 

and Cyclops. Cyclops decreased from 71 before 

treatment to 16 at 28 days after treatment, and 

nauplii decreased from 129 before treatment to 

36 at 28 days after treatment, but both were 

again abundant at 362 days after treatment. 

Fourteen genera of Chlorophyta, 12 of Chrysophyta, 1 of Pyrrophyta, and 5 of Cyanophyta 

were found. Melosira. Ceratium, Polycystis, 

and Aphanizomenon were the dominant organisms of these groups. These increased at 7 

days and 28 days after treatment. Approximately the same numbers were found in posttreatment collections at 362 days as were found 

before treatment. Numerical comparisons of 

pretreatment and posttreatment collections 

showed no marked changes.

12
TABLE 8. Number of plankton per liter in Odland Reservoir before and after 

toxaphene treatment at 5 parts per billion.

[Treated Aug. 11, 1960]

Organism

Brachionus..

Keratella...

Trichoceroa.

Asplanchna. .

Polyarthra. .

Synchaeta...

Fillnia. ....

Troohoephaer

Hexarthra...

Conochiloide

Daphnia. ....

Slmocephalus

Ceriodaphnia

Bosmiria. ....

Chydorus . . . ,

Diaptomus . . .

Cyclops.....

Nauplii 2 ...

Oedogonium. .

Rhizoclonium

Micro actinium

Pediastrum. .

Hydrodicton.

Oocystis....

Closteriopsi

Tetraedon. . .

Scenedesmus.

liougeotia...

Spirogyra. . .

Closterium. .

Cosmarium. . .

Staurastrum.

Oesmidium...

Botryococcus

Dinobryon. . .

lielosira. . . .

Diatoma.....

Synedra.....

Asterionella

Navicula. . . .

Pleurosigma.

Cymbella....

Nitzschia...

Cymatopleura

Ceratium. . . .

Polycystis. .

Lyngbya. ....

Anabaena ....

Aphanizomenon

Nodularia. . . .

Before,

Aug. 10, 1960

3

5

7

1

1

1 tr

22

31

*59

1

71

129

4

tr

10

tr

5

tr

1

3

3

6

2

tr

1

tr

1

6

tr

391

6

1

1

14

tr

Aug. 18, 1960

10

7

1

3

61

2

1

1

tr

tr

68

66

333

1

26

61

1

1

3

tr

1

5

1

3

tr

2

2

8

55

2

1

1

1

tr

tr

15

tr

542

9

1

5

287

1

After

Sept. 8, 1960

26

71

1

6

55

17

11

7

63

40

tr

37

24

2

1

16

36

3

10

2

1

1

7

1

1

1

tr

6

16

11'1

33

1

1

6

1

3

3,302

130

3

3

5,812

8

Aug. 8, 19*1

12

33

4

229

4

1

4

tr

tr

3

1

66

34

115

tr

12

2

1

1

1

2

131

16

4

tr

1

tr

1,123

3

5

4

TABLE 9. Number of plant-inhabiting organisms and bottom fauna in Odland 

Reservoir before and after toxaphene treatment at 5 parts per billion.

[Plant-inhabiting organisms expressed as number per pound of plants and 

bottom fauna as number per square foot of bottom. Treated August 11, I960]

1 Represents less than one per liter.

2 Includes nauplii of both Diaptomus and Cyclops.

Plant-inhabiting organisms. Four collections were made at two stations on the same 

dates plankton were collected. The number of 

organisms per pound of plants is given for each 

collection (table 9). Nineteen genera were taken, 

with Gammarus, Hydrachnidae, Caenis, Ischnura, Tendipes, Physa, Gyraulus, and Valvata 

being the most abundant. Caenis and Tendipes 

decreased slightly after treatment, probably a 

normal population fluctuation rather than a result of the toxaphene treatment. All other organisms remained nearly constant.

Bottom fauna. Four collections were made 

at the same stations on the same dates plant 

inhabiting organisms were collected. Each 

sample contained 4 square feet of bottom. The 

number of organisms per square foot of bottom 

is given for each collection (table 9). Fourteen 

genera were taken, but only Tendipes, Physa,

Organism

Oligochaeta... 

Hirudinea..... 

Amphipoda: 

Gammarus.....

Hydracarina: 

Hydrachnidae. 

Ephemeroptera:

Odonata:

Hemiptera: 

Notonecta. . . .

Trichoptera:

Coleoptera 

Haliplus. ...

Diptera: 

Tendipes. ... 

Probe zzla . . .

Gastropoda

C^raulus . . . . 

Valvata.. ...

Pelecypoda 

Pisidium. ...

Before, 

Aug. 10, 1960

Plant

tr 

195 

53 

21

1 

tr 

5

tr 

tr

tr 

tr

6 

tr

37

32 

1,301 

48

Bottom

2

1

2

tr

1

1

18 

tr

3

7

11

9

After

Aug. 18, 1960

Plant

tr 

294 

34 

11

tr 

4

1 

tr

1 

tr

6 

tr

52 

964 

52

Bottom

1 

2

tr

tr

8

1

9 

11 

17

11

Sept. 8, 1960

Plant

303 

4 

5

13

2

1

1 

2

4

23 

721 

U9

Bottom

1 tr

1

6

1

2 

tr 

tr

1 

17 

78

15

Aug. 8, 1961

Plant

2 

76 

17

11

2 

11

tr 

14

89 

320 

7

Bottom

2 

tr

tr

8 

tr

2 

2 

23

32

1 Less than 1 per pound or square foot.

Gyraulus, Valvata, and Pisidium were abundant. 

None of these exhibited marked numerical 

changes that could be attributed to toxaphene 

treatment.

EXPERIMENTS

Six Rotifera, two Cladocera, and two Copepoda 

were tested at six toxaphene concentrations 

ranging from 50 to 1,000 p.p.b., to determine 

their tolerance levels. All tests were conducted 

in battery jars, each containing 8 liters of filtered lake water taken at the site where the 

organisms were collected. The water had an 

average temperature of 68° F., a dissolved 

oxygen content of 9.8 p.p.m., total alkalinity of 

341 p.p.m., and pH of 8.4. Before each experiment the jars were washed with steel-wool soap 

pads and rinsed. All organisms were collected 

by pumping lake water through a No. 20 plankton 

net and were then placed in the jars. The toxaphene was diluted with water and applied to the 

water surface with moderate mixing, and after 

24 hours the plankters were removed by siphoning into a No. 20 plankton net and concentrated 

to 25 cc. All organisms in 2 cc. of this sample 

were counted. To avoid collecting the dead and

13
affected plankters the jars were tilted and 200 

cc. were left in the bottom after drainage. Three 

trials were conducted at each concentration, and 

the number of organisms counted was compared 

with untreated controls, which were maintained 

for all experiments (table 10).

Larger invertebrates were tested to determine the concentration at which 100 percent 

survived for 24 hours and 100 percent were 

killed (table 11). These tests were carried out 

in galvanized tanks, each containing 20 gallons 

of lake water at 71° F. The water used, toxaphene application, and cleaning method were the 

same as for zooplankters. In most cases 10 to 

20 organisms were used to calculate percent 

survival and mortality. Controls were maintained for 2 weeks, then discontinued, and survival was assumed to be 100 percent, with the 

exception of Gammarus which showed 91 percent survival.

Fathead minnows (Pimephales promelas) approximately 1 inch in length were placed in all 

containers after washing, for 48 hours at 10-

day intervals. This was done to determine 

whether large amounts of toxaphene were 

accumulating because of inadequate washing, 

since these minnows were found to have low 

tolerance levels (Hooper and Grzenda, 1957). 

The lowest concentration used in the experiments was 10 p.p.b., which produced 100 percent mortality among the test fish while all 

experimental organisms survived. No fathead 

minnows died in the washed tanks, and it was 

assumed that the procedure was adequate.

RESULTS

Marked reductions of rotifers were first observed at 500 p.p.b., cladocerans (Daphnia pulex 

and Boxmina) at 250 p.p.b., and copepods at 100 

p.p.b. (table 10). All genera in each group exhibited similar tolerance levels. Four trials 

employing 10 organisms each were conducted 

with Daphnia magna at six concentrations. No 

effects were obvious at 50 to 400 p.p.b., however retarded movements were observed at 

1,000 p.p.b., and movements had nearly ceased 

at 1,500 p.p.b. Prevost (I960) reported a median

TABLE 10. Comparison in number of zooplankters per cc. in 25-cc. concentrates from treated and control jars.

Polyarthra:

Trial 3

Hexarthra:

Trial 2

Filinia:

Keratella:

Asplanchna:

Brachionus :

T

-H-IQ-) T

Daphnia:

Bosmina:

Diaptoraus :

Cyclops :

TV-i A ~\ ?

Nauplii: 1

50 p.

Control

crt

34-

ttn

p.b.

Treated

£rt

Cf>

100 p

Control

-i A

/ rt

.p.b.

Treated

OK

~\ A

250 p

Control

-I ft

OftT

i AT

.p.b.

Treated

10

500 p

Control

Qft

IM

set

rtrt

-i rt'j

rtQ

.p.b.

Treated

ftft

750 p

Control

crt

ftft

34

flO

.p.b.

Treated

1,000

Control

Oi?

p.p.b.

Treated

1 Represents both Diaptomus and

14
TABLE 11. Percent survival of several aquatic invertebrates after 24 hours' 

exposure to toxaphene concentrations

Organism and toxaphene concentration

Hirudinea (2 trials):

1,000 p.p.b.................

Aniphipoda:

Gammarus (14 trials):

100 p.p.b...................

200 p.p.b...................

300 p.p.b...................

500 p.p.b...................

Hydracariha (4 trials):

1,000 p.p.b.................

Ephemeroptera:

Callibaetis (14 trials):

150 p.p.b...................

300 p.p.b...................

400 p.p.b...................

500 p.p.b...................

Odonata:

Aeschna (17 trials):

200 p.p.b...................

275 p.p.b...................

350 p.p.b...................

450 p.p.b...................

Lestes (21 trials):

450 p.p.b....................

500 p.p.b...................

600 p.p.b...................

350 p.p.b...................

Hemiptera:

Hotonecta (IS trials):

275 p.p.b...................

300 p.p.b...................

400 p.p.b...................

600 p.p.b...................

Sigara (19 trials):

50 p.p.b....................

 75 p.p.b....................

100 p.p.b...................

150 p.p.b...................

Trichoptera;

Limephilus (12 trials):

550 p.p.b...................

600 p.p.b...................

650 p.p.b...................

Coleoptera: 

Haliplus (22 trials):

10 p.p.b....................

40 p.p.b....................

50 p.p.b....................

75 p.p.b....................

Hydroporus (18 trials):

60 p.p.b....................

100 p.p.b...................

300 p.p.b...................

450 p.p.b...................

Qytiscus (Larvae) (9 trials):

15 p.p.b....................

50 p.p.b........:...........

60 p.p.b....................

75 p.p.b....................

Gyrinus (16 trials):

65 p.p.b....................

100 p.p.b...................

150 p.p.b...................

185 p.p.b...................

Gastropoda:

Lymnaea (4 trials):

700 p.p.b...................

Percent alive

100

39

21

0

100

71

13

0

100

84

40

0

100

81

33

0

100

71

39

0

100

60

25

0

100

49

20

0

100

45

11

0

100

63

35

0

100

76

58

0

100

78

60

0

tolerance limit (TL m) of 0.037 p.p.m. for 

cladocerans, and Hooper and Grzenda (1957) 

found Daphnia magna to have a TL m of 1.5 

p.p.m. at 55° F.

Tolerance levels (100-percent survival) for 

the larger invertebrates are listed in decreasing order as follows: Hirudinea, Hydracarina, 

Gastropoda, Trichoptera, Odonata, Hemiptera, 

Ephemeroptera, Amphipoda, Coleoptera 

(table 11). Survival at concentrations between 

100-percent survival and 100-percent mortality showed an approximate straight-line 

relation (table 11). Genera within each group

did not exhibit similar tolerance levels. This 

was evidenced among members of Odonata, 

Hemiptera, and Coleoptera. Lowered temperatures produced marked increases in tolerance 

levels. In Lestes tolerance increased approximately 35 percent by lowering the temperature 

10 degrees. Hooper and Grzenda (1957) found 

mortality in fathead minnows increased approximately threefold by raising the temperature 

from 50° F. to 75° F. Many of the findings are 

similar to those of Prevost (1960), however 

comparisons are difficult since he provided no 

temperature data.

DISCUSSION

Populations of plankton show many large 

variations throughout the year (Pennak, 1949; 

and Rawson, 1956). In the present study, the 

populations of organisms which could best 

illustrate posttreatment changes were not 

severely reduced, therefore no obvious effects 

could definitely be attributed to toxaphene treatment. Extensive fish removal can evidently be 

accomplished without seriously affecting the 

plankton, but large reductions in these organisms occur at 100 p.p.b. (Wollitz, 1958; and 

Hoffman and Olive, 1961). However, they reappear while the water is still toxic to fish 

(Tanner and Hayes, 1955), and begin repopulating before detoxification will permit fish 

survival.

No marked reductions were observed among 

most of the larger invertegrates. Hooper and 

Fukano( 1960) reported bottom fauna to be nearly 

as abundant in two Michigan lakes after treatment (10 p.p.b.) as before, but Stringer and 

McMynn (1958) found that Amphipoda was 

eliminated at 10 p.p.b. and Ephemeroptera at 

30 p.p.b. Severe reductions in many of these 

organisms may be expected at higher concentrations. Odonata, Ephemeroptera, Tendipedidae, 

and Chaoborus, were eliminated with 100 p.p.b. 

toxaphene (Hooper and Grzenda, 1957; and 

Gushing and Olive, 1957). Unionidae, Sphaeridae, 

Gastropoda, Oligochaeta, and Hirudinea appear 

to be more resistant (Hooper and Grzenda, 

1957); and Stringer and McMynn, 1958).

Field observations were supplemented by 

controlled experiments, since most organisms

15
tested were not reduced at concentrations used 

for fish removal. It should be recognized that 

lower tolerance levels probably exist under 

field conditions which involve longer exposure 

periods.

SUMMARY

Effects of different toxaphene concentrations 

on plankton and other aquatic invertebrates 

were studied under natural and controlled 

conditions. Five North Dakota lakes were included in the study, which extended from June 

through September of 1960 and 1961. Physical 

and chemical data are presented for each lake.

Polyarthra, Keratella, Asplanchna, Gonochiloides, Brachionus, Trichocera, Daphnia, 

Bosmina, Geriodaphnia, and Cyclops were the 

dominant zooplankters. No marked reductions 

were observed after treatment with 5 to 35 

p.p.b., but a marked reduction of many plankters 

followed the second treatment (90 p.p.b.) in 

Raleigh Reservoir. The Cyanophyta were the 

most abundant phytoplankters in all lakes. 

Aphanizomenon increased in all lakes after 

treatment, but other phytoplankters exhibited 

no consistent changes. Chlorophyta, Chrysophyta, and Pyrrophyta contributed little to 

phytoplankton abundance.

The most abundant plant-inhabiting organisms and bottom fauna exhibited no marked 

changes after treatment. Gammarus, Physa, 

Gyraulus remained almost constant, while 

Gallibaetis, Gaenis, Ischnura, and Tendipes 

decreased slightly but were again numerous 1 

year after treatment.

Tests on several species of zooplankters 

showed Rotifera to be the most tolerant, followed by Cladocera and Copepoda. Reductions 

were in Rotifera at 500 p.p.b., in Cladocera at 

250 p.p.b., and in Copepoda at 100 p.p.b. Experiments with the larger invertegrates showed 

Hirudinea, Hydracarina, and Gastropoda to be 

the most resistant to toxaphene, followed in 

order by Trichoptera, Odonata, Hemiptera, 

Ephemeroptera, Amphipoda, and Coleoptera. 

Survival among the larger invertegrates at 

intermediate concentrations between 100-percent survival and 100-percent mortality revealed an approximate straight-line relation. 

Genera within each group exhibited dissimilar 

tolerance levels.

REFERENCES

Gushing, Colbert E., Jr., and John R. Olive.

1957. Effects of toxaphene and rotenone upon the 

macroscopic bottom fauna of two northern Colorado 

reservoirs. Transactions of the American Fisheries Society, vol. 86 (1956), p. 294-301.

Hoffman, Dale A., and John R. Olive.

1961. The effects of rotenone and toxaphene upon 

plankton of two Colorado reservoirs. Limnology 

and Oceanography, vol. 6, No. 2, p. 219-222.

Hooper, Frank F., and Kiyashi G. Fukano.

1960. Summary of experimental lake treatments with 

toxaphene 1954-58. Institute for Fisheries Research 

Michigan Department of Conservation. 17 p. (Manuscript).

Hooper, Frank F., and Alfred R. Grzenda.

1957. The use of toxaphene as a fish poison. Transactions of the American Fisheries Society, vol. 85 

(1955), p. 180-190.

Pennak, Robert W.

1949. Annual limnological cycles in some Colorado 

reservoir lakes. Ecological Monographs, 19:233-267.

1953. Fresh-water invertebrates of the United States. 

New York, Ronald Press Co. 769 pp.

Prevost, G.

1960. Use of fish toxicants in the Province of Quebec, 

Canadian Fish Culturist, vol. 28, p. 13-35.

Rawson, D. S.

1956. The net plankton of Great Slave Lake. Journal 

of the Fisheries Research Board of Canada, vol. 13, 

p. 56-127.

Stringer, George E., and Robert G. McMynn.

1958. Experiments with toxaphene as a fish poison.. 

Canadian Fish Culturist, vol. 23, p. 39-47.

Tanner, H. A., and M. L. Hayes.

1955. Evaluation of toxaphene as a fish poison. Colorado Cooperative Fishery Research Unit, Quarterly 

Report 1, p. 31-39.

Ward, Henry B., and G. C. Whipple.

1959. Fresh-water biology. John Wiley & Sons. 1248 p.

Wollitz, R. E.

1958. The effects of certain commercial toxicants on 

the limnology of three cold water ponds near Three 

Forks, Montana. M.S. thesis, Montana State College. 

63 p.

16
INVESTIGATIONS IN FISH CONTROL

5. Growth Rates of Yellow Perch 

in Two North Dakota Lakes

After Population Reduction with Toxaphene

By Donald C. Warnick, Fishery Biologist

U.S. DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

Bureau of Sport Fisheries and Wildlife

Resource Publication 9

Washington . January 1966
CONTENTS

Page

Abstract. ....................................... 3

The study lakes ................................... 4

Age and growth ................................... 5

Discussion ...................................... 6

Summary and conclusions ............................ 8

References ...................................... 8
GROWTH RATES OF YELLOW PERCH IN TWO

NORTH DAKOTA LAKES AFTER POPULATION

REDUCTION WITH TOXAPHENE

By Donald C. Warnick, Fishery Biologist

Abstract. Growth rates of yellow perch that survived a toxaphene treatment in Brush and Long Lakes in North Dakota were calculated by the 

scale method for the 1960 and 1961 growing seasons. Brush Lake fish exhibited greatly increased growth rates for both growing seasons following 

the treatment. Increased growth rates were not evident for Long Lake fish 

until the 1961 growing season. At the end of the first full growing season 

after treatment the surviving yellow perch exceeded what may be considered to be the minimum harvestable size of 7 inches. The approximate 

concentration of toxaphene for reducing the density of fish populations is 

believed to be 25 percent of the rate determined for fish eradication in 

most North Dakota waters.

Waters overpopulated with desirable species 

generally produce few harvestable fish, because of slow growth. Bennett (1962) stated 

that no fish of harvestable size were found in 

some waters thus affected; Eschmeyer (1936) 

made a similar observation concerning overcrowded populations of yellow perch (Perca 

flavescens). For lack of more efficient remedial measures the use of piscicides has 

been recommended to reduce the numbers of 

the problem species.

Relatively low concentrations of toxaphene 

(chlorinated camphene) in two North Dakota 

lakes substantially reduced the density of the 

yellow perch populations; the effect on other 

fish species was less obvious. The results reported (Henegar, 1965) were incidental to the 

determination of the minimum toxaphene concentration necessary for fish control in that 

State. My study was started in 1960 to determine the growth rates of the yellow perch surThis publication is based on a thesis submitted to the 

Graduate Faculty, Department of Entomology-Zoology, 

South Dakota State College of Agriculture and Mechanic 

Arts, in partial fulfillment of the requirements for the 

degree of Master of Science, June 1963.

viving in Brush and Long Lakes, and thus gain 

information concerning the suitability of toxaphene for reducing the numbers of fish in 

overpopulated waters. The scale method was 

employed to calculate growth rates of Brush 

Lake fish for the 1960 and 1961 growing seasons. Posttreatment growth rates of Long Lake 

fish were determined for part of the 1960 

growing season and for all of the 1961 season.

Several authors reporting on the use of 

rotenone to thin overcrowded populations or 

to restore balance among fish species considered the results favorable. Beckman (1941) 

noted that the growth rates of fish surviving the 

treatment of half of Booth Lake, Mich., were 

too great to be accounted for by normal variation. Substantially increased harvests, apparently the results of accelerated growth rates 

of remaining fishes, were reported by Swingle, 

Prather, and Lawrence (1953) following treatment of some Alabama ponds. Hooper and 

Crance (1960) stated that the use of rotenone 

was an effective and economical way to restore 

balance in certain fish populations. The use of 

toxaphene was recommended by several authors 

including Hemphill (1954) who first used the 

chemical for fish eradication.
Cost of fish eradication with toxaphene is 

approximately 15 percent of the cost with 

rotenone. With recommended concentrations 

and methods for thinning overcrowded fish 

populations with these chemicals, toxaphene is 

even more economical. Definite information 

about this use of the poison and the subsequent 

results is conspicuously absent.

Unfavorable results from the early use of 

toxaphene for fish eradication were not uncommon and tended to delay the acceptance of the 

piscicide for use in fishery management (Prevost, 1960). Consequences of a serious nature 

were the failure of the poison to kill all fish; 

the extended toxicity of some treated waters; 

and the reduction or elimination of many 

aquatic organisms. Hooper and Grzenda (1955) 

first suggested that such results were due to 

confusion concerning lethal concentrations and 

the belief was substantiated by the accumulation of additional evidence (Stringer and 

McMynn, 1960). Increased proficiency in using 

the chemical for fish eradication led to its 

acceptance for that purpose as indicated by 

Gebhards 1 1960 review of past and proposed 

use in western states.

Toxaphene concentrations used for fish eradication reportedly reduce or eliminate many 

fish-food and food-chain species, some of which 

do not reappear in quantity for extended periods 

(Stringer and McMynn, 1958). Relatively little 

is known concerning the effects of the lesser 

toxaphene application rates recommended for 

reducing the density of overcrowded fish populations. A paucity of fish-food organisms in 

the North Dakota lakes even for a comparatively short period after toxaphene application would affect growth rates of the surviving 

fish as indicated by scale analysis.

I am obliged to Dale L. Henegar, Chief of 

Fisheries, North Dakota Game and Fish Department, who brought to my attention the 

opportunity for this investigation, and to the 

fishery personnel who assisted with the field 

work. I wish to thank Marvin O. Allum, Associate Professor of Zoology, for his counsel 

during the study, and the other faculty members and fellow graduate students of South 

Dakota State College for their interest and 

assistance.

THE STUDY LAKES

The minimum concentration of toxaphene 

required for fish eradication is determined on 

the basis of the physical and chemical characteristics of the water for which treatment is 

proposed in addition to certain biological conditions, and this is assumed to be true with 

regard to application rates for reducing the 

density of fish in over populated waters. Some 

physical and chemical characteristics of Brush 

Lake and Long Lake are presented in table 1. 

The following history is pertinent to the study 

of the posttreatment growth rates and is basecf 

on material presented by Henegar in 1961 

(Henegar, 1966).

Both lakes were treated with toxaphene to 

produce concentrations of approximately 0.01C 

parts per million (p.p.m.) using an emulsifiable 

concentrate containing 6 pounds of the active 

ingredient per gallon. Brush Lake was treated 

on October 5, 1959, and Long Lake on July 17, 

1960. The method of application was that commonly used by the North Dakota Game and Fish 

Department, and similar to that described by 

Stringer and McMynn (1958).

Dilution of the waters by rainfall or by runoff was inconsequential after toxaphene treatment, because of unusual drought. Water levels 

receded somewhat during the course of the 

study. Rooted aquatic vegetation was along portions of the shoreline and in several small 

shallow areas of Long Lake at the time of 

treatment, but was nearly absent from Brush 

Lake because of the late-season treatment 

date.

Apparently, all young-of-the-year yellow 

perch were eliminated from both lakes.

TABLE 1. Physical and chemical characteristics of the lakes

Item

^tti

Phenolphthalein alkalinity (p.p.m. J 1 . 

Methyl orange alkalinity (p.p.m.) 1 ...

Total dissolved solids (p.p.m.) 1 .....

Brush Lake

40 

460

290

Long Lake

8.2

40 

220 

308

307

1 Condition on date of application.
Observations established deaths of some youngof-the-year northern pike (Esox lucius) in Long 

Lake, but posttreatment netting disclosed they 

were not eliminated. The effect of the poison on 

adult fish of several species in both lakes was 

less evident than the effect on yellow perch, the 

dominant species.

Excluding the young-of-the-year, yellow 

perch density was reduced approximately 91 

percent in Brush Lake and 79 percent in Long 

Lake. The figures are derived from the results 

of test-netting just before and several months 

after poisoning. Netting results also indicated 

that a greater percentage of the smaller yellow 

perch (less than 140 millimeters) was eliminated than of the larger fish. Observation of 

Long Lake for several days after toxaphene 

application tended to substantiate the netting 

results.

Populations of fathead minnows (Pimephales 

promelas) were established in the lakes after 

treatment. Brush Lake was stocked on May 27, 

1960, and Long Lake on August 18, 1960. Introduction of minnows after toxaphene treatment 

is a general practice of the North Dakota Game 

and Fish Department.

AGE AND GROWTH

Varied evidence has been presented in support of the validity of the scale method for the 

determination of the age and growth of fishes 

(Lee, 1920; Van Oosten, 1929). Similar evidence 

indicates that the method is valid for determining the age and growth rates of yellow perch. 

Joeris (1957) indicated that additional evidence 

on the validity of the annulus world accumulate 

from the further study of Green Bay (Lake 

Michigan) perch. Jobes, as early as 1934, assumed the validity of the method for yellow 

perch. The North Dakota study was based on 

the assumption that the method is valid.

Scale samples of yellow perch from the study 

lakes were obtained from specimens netted before and after the poisoning, from poisoned 

fish, and from winterkilled specimens.

It was apparent during analysis of the scale 

samples from Long Lake, July 12-17,1960, that

distinction of age classes would be difficult. 

Determination of the age composition for this 

group was dependent on the identification of all 

annuli for each scale sample. For many samples 

it could not be established whether the 1960 

annulus had been formed. The samples from 

smaller fish (80-120 millimeters) generally 

evidenced annulus formation and some subsequent growth, but the 1960 annulus was apparently unformed on some of the scales of larger 

fish. Because of relatively little scale growth 

the previous season, it could not be determined 

whether the annulus was recently formed and 

the later scale growth was of the 1960 growing 

season, or the annulus was unformed and the 

scale growth of the previous year was represented. An error of 1 year would be introduced 

by the wrong choice.

A similar difficulty was noted by Joeris 

(1957) during analysis of yellow perch scales. 

Beckman (1943) reported that the time of annulus formation may vary notably among species 

and within age groups of the same species. 

Annulus formation probably would have occurred before the July collection date with 

more favorable growth conditions.

Even without this difficulty, determination of 

age classes would have been somewhat subjective. Annuli were not distinct, and markings 

assumed to be false annuli were common. Consequently the age classes and specific growth 

rates of fish before treatment are not included.

Posttreatment scale samples from both lakes 

were obtained after the interruption of growth 

for the 1961 season and before 1962 growth 

was begun. An annulus was assumed at the 

scale margin although none was evident. All 

discernible increase in scale growth of the 

Long Lake fish was included between the margin and the annulus of the previous year. The 

scale growth of Long Lake fish during the 1960 

season after poisoning was not distinguishable 

from previous scale growth. Growth increments for the 1961 growing season are presented in table 2. Errors other than mechanical 

are unlikely because of the distinctive scale 

growth and the absence of false annuli during 

that period.
TABLE 2. Calculated growth increments of yellow perch from Long Lake for 

the 1961 growing season

[In millimeters]

TABLE 3. Calculated growth increments of yellow perch from Brush Lake fothe 1960 and 1961 growing seasons

[in millimeters]

Number of 

fish

171 ............

Oft

Total length at capture

Range

103-132 

201-210

221-230 

231-240 

241-250 

251-260 

261-270

Average

115 

178 

205 

219 

227 

235 

247 

253 

265

Calculated growth increment

Range

58-101

59-120 

45-116 

56-106 

75-116 

54-99

Average

82 

75 

59 

74 

75 

79 

83 

78

1 Young-of-the-year in 1961.

Scale samples were not obtained from Brush 

Lake fish until 2 years after treatment. Accelerated scale growth was obvious between the 

scale margin and annuli of the 2 previous 

years. The calculated growth rates for the 

corresponding periods are contained in table 3. 

As in the scales of Long Lake fish, growth 

before poisoning was obscured by the presence 

of numerous false annuli.

When an annulus of the year previous to those 

located for the preparation of tables 2 and 3 

was obvious, as it was on some scales, a direct 

comparison of scale growth before and after 

poisoning was made. On this basis the posttreatment growth during the first year was approximately six times greater than for the 

previous year.

Table 4 shows the relation of fish length to 

subsequent growth both calculated. The fact 

that greater length increments were recorded 

for smaller fish lends validity to the scale 

method as applied here.

A change in the size composition of Long 

Lake fish is evident in table 5. The numbers of 

fish in the last column represent a subsample 

of winterkilled specimens in addition to several obtained by qualitative test-netting. The 

numbers of fish in the other columns represent 

test-netting results at the times indicated. Excluding the 17 young-of-the-year of 1961, the 

lengths of fish listed in the last column are 

approximately 75 to 100 millimeters greater 

than the lengths of fish listed in the previous 

column. Despite the time interval, only one 

growing season, 1961, is represented. The calculated average growth increment for the period was 82 millimeters.

Number of 

fish

--i

8....................

Total length 

at capture

201-225

oo£,_9<sn

276-300

Average 1960 

increment

95

100

Average 1961 

increment

98

45

51

57

Young-of-the-year in 1960.

TABLE 4. Relation of fish lengths to subsequent growth increments (both 

calculated) for yellow perch from Long Lake

[in millimeters]

Number of 

fish

171 ... ...............

1. ...................

Calculated length, 

May 1961

103-132 

91-100 

101-110 

111-120 

121-130 

131-140 

141-150 

151-160 

161-170 

171-180 

181-190 

191-200 

201-210

Growth increment 1961

Range

103-132 

82-121 

101-119

64-116 

61-104 

58-96 

59-101 

67-89 

45-82

Average

115 

101 

110

92

85 

76 

76 

75 

67 

66 

54

1 Young-of-the-year in 1961; lengths are measured total lengths.

TABLE 5. Toxaphene-effected change in the yellow perch population of Lonp 

Lake based on measured total lengths of fish taken during the study

Length range

251-275 mm. ..................

Total. .....................

Number of fish

Before treatment 

(July 1960)

1,010 

527 

312 

198 

196 

7 

0 

0 

0

2,250

After treatment

October 1960

0 

0 

0 

152 

243 

0 

0 

0 

0

395

May 1962

0 

0 

1 17 

0 

0

1

12

75 

19

124

1 Young-of-the-year in 1961.

DISCUSSION

The yellow perch is a popular species in 

recreational fisheries, especially for winter 

fishing, but fish shorter than a total length of 

7 inches or approximately 175 millimeters are 

not often sought and removed by fishermen. If 

this length is considered the minimum harvestable size, the growth rates recorded for the 

yellow perch from the North Dakota lakes are 

significant with respect to the short time required for the improvement of recreational 

fisheries. All yellow perch surviving similar 

treatment rates could be expected to exceed the 

minimum desirable size during the subsequent 

growing season, and young-of-the-year after 

only two growing seasons.
Young-of-the-year yellow perch commonly 

reach harvestable size in three or more growing seasons except in overpopulated waters 

where growth is restricted. Growth rates of 

surviving fish were exceptionally rapid during 

the growing season following treatment 1960 

for Brush Lake and 1961 for Long Lake when 

compared with growth rates of yellow perch in 

other areas. Similar growth increments have 

not been recorded even for more southern latitudes with longer growing seasons (Carlander, 

1953).

On the basis of this study, better recreational fishing cah be provided at low cost in 

some lakes and small impoundments overpopulated with yellow perch. Improved angling was 

assumed in the North Dakota lakes since more 

fish of harvestable size were produced, but the 

determination of increased harvests would be 

conclusive. Comparable results might also be 

expected following the thinning of other commonly overpopulated species inasmuch as my 

study was opportunistic, not a deliberate selection of species.

Low toxaphene concentrations in North 

Dakota lakes have been observed to eliminate 

small fish of many species including the bullhead (Ictalurus melas), reported by Kallman, 

Cope, and Navarre (1962) to be somewhat resistant to the toxicant. The policy in North 

Dakota of introducing minnows in waters after 

treatment with toxaphene is based on this observation.

An assumed absence of prey fish may explain the continued slow growth of yellow perch 

in Long Lake during the 1960 growing season, 

after the mid-July application of toxaphene. 

The May 27, 1960, introduction of 180,000 

fathead minnows in Brush Lake evidently assured the presence of significant numbers for 

the same growing season and no unusual period 

of slow growth was apparent from scale analysis. The reduction or elimination of prey fish 

by the mid-July poisoning and the August 18, 

1960, stocking of 200,000 fathead minnows, 

leaves doubt whether significant numbers were 

present in Long Lake until the 1961 growing 

season when growth rates of yellow perch were 

greatly accelerated. A need for more conclusive information concerning the relation of prey 

species to growth rates is indicated.

Assuming need for the introduction of prey 

species, a definite advantage is apparent for 

the fall treatment of waters since stocking can 

be accomplished early in the subsequent growing season. Treatment in April or May is probably more advantageous than during the 

growing season, but conditions then are not 

favorable for rapid detoxification, and stocking 

of prey species might have to be delayed.

The toxaphene treatment rate which allowed 

the survival of yellow perch in the North Dakota 

lakes was approximately one-third of the determined rate for fish eradication in most 

waters of that State. A belief that the reductions 

were excessive can be temporized since the 

possibility that an optimum number of fish 

survived in either lake is unlikely, and greater 

growth rates could hardly be expected. Testnetting of both lakes and observation after a 

partial winterkill of Long Lake in 1962 substantiates the belief. Concentrations approximating 0.008 p.p.m. (one-fourth of the minimum 

lethal rate) probably would have allowed the 

survival of more fish without significantly reducing growth rate.

On the basis of a recent report by Kallman, 

Cope, and Navarre (1962), the presence of 

relatively large quantities of vegetation at the 

time of treatment could affect the outcome, 

especially in consideration of the low toxaphene 

concentrations required for the thinning of fish 

populations. It was indicated that high concentrations of toxaphene are accumulated by certain vegetative species in a relatively short 

time, thus essentially removing the chemical 

from the water at least temporarily and the 

further disposition of the chemical was unknown. Therefore, more consistent results 

might be obtained, with regard to the degree 

of reduction, by treatment during the absence 

of most aquatic vegetation.

The appropriate reduction for any population 

necessarily depends on a variety of conditions, 

some unknown. The difficulty of determining 

the magnitude of fish populations, particularly 

after treatment, seriously affects an evaluation of the results. Additional information concerning the use of toxaphene for reducing the 

density of fish populations is needed for its 

greatest usefulness.
SUMMARY AND CONCLUSIONS

Yellow perch populations in two North Dakota 

lakes were substantially reduced by low toxaphene concentrations. Growth rates of surviving fish were determined by the scale method 

for 2 years after treatment. Greatly increased 

growth rates were evident for both growing 

seasons following the fall treatment of Brush 

Lake. Increased growth rates were not evident 

for Long Lake fish after the July 17, 1960, 

treatment until the 1961 growing season. All 

yellow perch surviving the poisoning exceeded 

what may be considered to be the minimum 

harvestable size during the first full growing 

season after treatment. Comparable results 

can be expected from similar and perhaps 

lesser reductions with toxaphene.

Further use of toxaphene is recommended 

for reducing the density of yellow perch populations and thus improving certain recreational 

fisheries. Other species might be similarly 

managed. Reduction or elimination of prey 

species was believed to explain the continued 

slow growth of Long Lake fish for approximately 2 months after toxaphene application. 

Fall treatment is apparently the most timely, 

especially with regard to assuring the presence 

of significant numbers of prey species during 

the growing season. Numerous conditions affect 

the concentration of toxaphene needed for fish 

eradication, and the approximate concentration 

for reducing the density of fish populations is 

believed to be 25 percent of that rate.

REFERENCES

Beckman, William C.

1941. Increased growth rate of rock bass (Amblopites 

rupestris Rafinesque), following reduction in the 

density of the population. Transactions of the American Fisheries Society, vol. 70, p. 143-148.

1943. Annulus formation on the scales of certain game 

fishes. Papers, Michigan Academy of Science, Arts, 

and Letters, vol. 28, p. 281-312.

Bennett, George W.

1962. Management of artificial lakes and ponds. 

Reinhold Publishing Co., New York. 283 p.

Carlander, Kenneth D.

1953. Handbook of freshwater fishery biology with the 

first supplement. Wm. C. Brown Co., Dubuque, 

Iowa. 281 p.

Eschmeyer, R. William.

1936. Some characteristics of a population of stunted 

perch. Papers, Michigan Academy of Science, Arts, 

and Letters, vol. 22, p. 613-628.

Gebhards, Stacy V.

1960. A review of toxaphene for use in fish eradication. Idaho Department of Fish and Game. 14 p.

Henegar, Dale L.

1966. Minimum lethal levels of toxaphene as a piscicide in North Dakota lakes. U.S. Bureau of Sport 

Fisheries and Wildlife, Investigations in Fish Control No. 3.

Hemphill, Jack E.

1954. Toxaphene as a fish toxin. Progressive FishCulturist, vol. 16, No. 1, p. 41-42.

Hooper, Archie D., and Johnie H. Crance.

1960. Use of rotenone in restoring balance to overcrowded fish populations in Alabama lakes. Transactions of the American Fisheries Society, vol. 89, 

No. 4, p. 351-357.

Hooper, Frank F., and Alfred R. Grzenda.

1957. The use of toxaphene as a fish poison. Transactions of the American Fisheries Society, vol. 85 

(1955), p. 180-190.

Jobes, Frank W.

1932. Preliminary report on the age and growth of the 

yellow perch from Lake Erie, as determined from a 

study of its scales. Papers, Michigan Academy of 

Science, Arts, and Letters, vol. 17, p. 643-652.

Joeris, Leonard S.

1957. Structure and growth of scales of yellow perch 

of Green Bay. Transactions of the American Fisheries Society, vol. 86, p. 169-194.

Kallman, Burton J., Oliver B. Cope, and Richard J. 

Navarre.

1962. Distribution and detoxification of toxaphene in 

Clayton Lake, New Mexico. Transactions of the 

American Fisheries Society, vol. 91, No. 1, 

P. 14-22.

Lee, Rosa M. (Mrs. T. L. Williams).

1920. A review of the methods of age and growth determination in fishes by means of scales. Ministry 

Agriculture and Fisheries, Fishery Investigations, 

ser. 2, 1-32. (Fredericton, New Brunswick).
Prevost, G. Swingle, H. S., E. E. Prather, and J. M. Lawrence.

1960. Use of toxicants in the Province of Quebec. 1953. Partial poisoning of overcrowded fish populaCanadian Fish Culturist, vol. 28, p. 13-35. tions. Alabama Polytechnic Institute, Auburn, Ala.

Stringer, George E., and Robert G. McMynn.

1958. Experiments with toxaphene as a fish poison. ,«2?Stfn' % f ,_ , , ,_ . ,_ . 

Canadian Fish Culturist, vol. 23, p. 1929- JTiff ^^ * th,e ^ke herring (Leucichythys

artedi LeSeuer) of Lake Huron as revealed by

1960. Three years' use of toxaphene as a fish toxicant its scales, with a critique on the scale analysis, 

in British Columbia. Canadian Fish Culturist, vol. U.S. Bureau of Fisheries, Document 1053. 

28, p. 37-44. 250 p.

INVESTIGATIONS IN FISH CONTROL

6. Mortality of Some Species of Fish 

to Toxaphene at Three Temperatures

By Mahmoud Ahmed Mahdi, Fishery Biologist

U.S. DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife 

Resource Publication 10 

Washington . January 1966
CONTENTS

Page

Abstract. .......................................... 3

Methods ........................................... 3

Water. ......................................... 4

Transfer of fish................................... 4

Introduction of toxaphene............................. 5

Observations. .................................... 5

Analysis........................................... 5

Results. ........................................... 7

Change with time .................................. 7

Change with temperature............................. 8

Species comparisons. ............................... 8

Oxygen......................................... 9

Summary .......................................... 9

References ......................................... 10
MORTALITY OF SOME SPECIES OF FISH TO TOXAPHENE 

AT THREE TEMPERATURES

By Mahmoud Ahmed Mahdi, Fishery Biologist

Abstract. Lethal concentrations of toxaphene were determined for the 

stoneroller, golden shiner, goldfish, black bullhead, and bluntnose minnow in 

water at 53° F., 63° F., and 73° F.; rainbow trout were tested at 53° F. The 

TLm and LD$Q were obtained by graphic methods. For comparison a normit 

method was used with the bluntnose minnow data; all three methods gave 

similar results for the bluntnose minnow. In most experiments, concentrations of toxaphene needed to cause 50 percent mortality decreased as the 

temperature increased from 53° F. to 63° F. and to 73° F. The 96-hour TL m 

values were below 0.1 p.p.m. of toxaphene in all species tested. Goldfish 

were the most tolerant, with the other species showing so similar a sensitivity that they could not be effectively ranked by these data.

Toxaphene (chlorinated camphene) is used 

widely as an insecticide on farm crops and as a 

poison to control fish populations (Henderson et 

al., 1959; Fukano and Hooper, 1958). Toxaphene 

is highly toxic, especially to man, and is never 

recommended for household use (it can be absorbed through the skin). For mammals, toxaphene is one of the more toxic of the chlorinated hydrocarbon insecticides (Cohen et al., 

1960, p. 1552). Negherbon (1959) lists it as 

being more toxic to fish than DOT or rotenone. 

Toxaphene is nonvolatile, yellow to amber in 

color, and has an aromatic, pinelike smell. It 

is insoluble in water but soluble in organic solvents (Henderson et al., 1959). The emulsion 

used in this investigation was milky white.

This study was an attempt to determine the 

concentrations of toxaphene that will kill certain 

species of fish. Three temperatures were used, 

to ascertain the role temperature plays in the 

toxicity of toxaphene.

This publication is based on a thesis submitted to the 

Graduate Faculty, Iowa State University of Science and 

Technology, in partial fulfillment of the requirements 

for the degree of Master of Science. Studies were conducted under a grant made through the Sudanese Government by the Agency for International Development.

I am indebted to Dr. Kenneth D. Carlander 

for his help in interpreting the data and in putting this work in its final form. I am obliged 

also to T. Hoage, Dr. V. Gooch, J. Reynolds, 

and C. Caillouet for their advice on interpretation of the data, and to Charles Walker of the 

Fish Control Laboratory, La Crosse, Wis., who 

supervised the experiments.

METHODS

These experiments were carried out at the 

Fish Control Laboratory of the Bureau of Sport 

Fisheries and Wildlife at La Crosse, Wis. The 

fish were provided by the Laboratory and from 

various sources, including hatcheries. The following species were tested:

1. Rainbow trout, Salmo gairdneri.

2. Stoneroller, Campostoma anomalum.

3. Goldfish, Carassius auratus.

4. Golden shiner, Notemigonus crysoleucas.

5. Bluntnose minnow, Pimephales notatus.

6. Black bullhead, Ictalurus melas.

Before starting an experiment the fish were 

examined thoroughly to make sure that there 

were no signs of disease. They were left in
large holding tanks and fed regularly until 2 

days before the start of the experiment. To 

keep to a minimum waste products that might 

affect toxicity, they were not fed during the 

experiments.

WATER

Deionized water was reconstituted by adding 

a mixture of 0.45 grams of calcium sulphate, 

0.45 grams of manganous sulphate, 0.72 grams 

of sodium bicarbonate, and 0.03 grams of 

potassium chloride, giving 1.65 grams of a 

powdered mixture for every 15 liters of water. 

This reconstituted water has the following 

characteristics:

pH ................... 7.9

Carbon dioxide ........... 1.0 p.p.m.

Total alkalinity. .......... 36.0 p.p.m.

Total hardness ........... 72.0 p.p.m.

Calcium hardness ......... 26.0 p.p.m.

Manganese. ............. 0.075 p.p.m.

Sulphate ion ............. 37.5 p.p.m.

Chloride ion. ............ 6.86 p.p.m.

Ammonia nitrogen ......... 0.05 p.p.m.

Total ion ............... 0.00 p.p.m.

The reconstituted water was aerated for 24 

hours and was then transferred into glass jars 

of two sizes, large ones containing 15 liters of 

water and small ones of 1 gallon each. Each 

sized jar was large enough to hold the required 

volume of water at a point somewhat below the 

rim. The large jars were placed in concrete 

tanks about 30 inches deep and 3 feet wide, 

where they were allowed to rest in the water. 

Eighteen jars were used in each experiment, 

including three for controls and three each for 

five different concentrations. Sometimes additional jars were used to permit more than five 

concentrations in an experiment. The small 

jars were put in aluminum troughs 1 foot deep; 

four small jars were used for the control and 

15 for each concentration.

Circulating water pumps were used to mix 

water in tanks and aluminum troughs to ensure 

an even temperature. Elevated temperatures 

were maintained with electric water heaters 

and thermostats. A small thermogrph recorded 

the temperature of the water, and these records 

indicated good temperature control.

TRANSFER OF FISH

Hand nets that were used to take fish out of 

the tanks were kept in an antiseptic solution (c^ 

milliliters of Roccal to 25,000 milliliters of 

water) when not in use. The fish were transferred into a bucket of water mixed with 

acriflavine (concentration not critically determined). Douglas and Irwin (1962) found that 

Terramycin and acriflavine in small amounts 

were successful in combating fin or tail rot. 

The fish were not overcrowded, but to ensure 

an abundance of oxygen, air was run into the 

bucket. During the transfer, any fish which fell 

to the floor were not used in the experiment.

After making sure that the water temperature 

in the jars was adjusted, the fish were weighed 

and placed in the jars to be acclimatized for 

another 24 hours. To ensure that the fish were 

not overcrowded, they were introduced according to the loading capacity of each species by 

weight, making sure that the weight of fish 

should not exceed the safe range. In the case of 

the lowest temperature used, 53° F., the safe 

range of the loading capacity of each jar for 

different species of fish had been determined 

by the staff of the Fish Control Laboratory. 

Experiments were run to determine the safe 

loading capacity at 73° F. of several species of 

fish (table 1). From these data it is clear that 

up to 2 grams of goldfish per liter of water can 

be used safely for a period of 96 hours. For tl « 

golden shiner and the stoneroller, up to 1 gram 

of fish per liter of water can safely be used fcr 

96 hours. Two grams of golden shiner per liter 

of water can be used, but not for more than 72 

hours, whereas the same loading capacity is 

not advisable for the sonteroller even for the 

first 24 hours.

The largemouth bass can stand up to 2 grams 

of fish per liter of water only for the first 24 

hours. If bass are to be used for more than 24 

hours, one-fourth gram of fish per liter of 

water could only be used for not more than 48 

hours. Otherwise less loading should be tried.

No loading capacity tests were run at 63° F., 

but loading capacities exceeding those found at 

73° F. were not used.
1AKLE 1. Percentage mortality of four species of fish, and dissolved oxygen in parts per million, at different loading capacities at 73° F.

Fish and time

Stoneroller:

Goldfish:

Golden shiner:

Largemouth bass:

At a load per liter of water of 

0.25 gram of fish

Fish killed

Percent

0 

0 

0 

0

0 

0 

0 

0

0 

0 

25 

25

Oxygen

F.p.m.

3.5 

2.6 

2.8

5.3 

3.9 

3.5

5.3 

4.1 

3.7

0.5 gram of fish

Fish killed

Percent

0 

0 

0 

0

0 

0 

0 

0

0 

0 

0 

0

0 

33 

33 

33

Oxygen

P.p.m.

3.5 

2.6 

2.7

2.9

1.7 

2.0

3.8 

2.7 

3.1

4.3 

2.5 

2.5

1.0 gram of fish

Fish killed

Percent

0 

0 

0 

0

0 

0 

0 

0

0 

0 

0 

0

8 

31 

31 

31

Oxygen

F.p.m.

1.6

1.4 

1.5

1.4 

1.0 

1.6

1.9 

3.1 

3.7

2.2 

1.6 

2.0

2.0 grams of fish

Fish killed

Percent

38 

38 

38 

50

0 

0 

0 

0

0 

7 

7 

15

4 

22 

26 

26

Oxygen

P.p.m.

1.6 

1.3 

1.3

0.9 

0.8 

0.8

1.6 

1.5 

1.5

0.9 

0.8 

1.3

INTRODUCTION OF TOXAPHENE

Toxaphene solution was prepared fresh from 

commercial stock each time it was to be introduced into the jars. The commercial stock was 

a solution of 4 pounds per gallon. Two milliliters of the commercial stock were transferred to a 1-liter flask, and deionized water 

was added to make 1 liter of solution. When 1 

milliliter of this solution was added to 1 liter 

of water it gave approximately 1 part per million of the toxicant. The toxaphene concentration was calculated according to this and introduced into the different jars as required. When 

very dilute solutions were required, the stock 

solution was further diluted by taking 100 

mililiters of it and adding 1 liter of deionized 

water, making a new stock solution (0.0001 

toxaphene) of which 1 milliliter in 1 liter of 

water gave 0.1 p.p.m.

In the introduction of the toxicant, 1-milliliter, 2-milliliter, and 5-milliliter pipettes 

were used. To avoid suction of the toxicant and 

to speed the introduction of the toxaphene into 

the jars, the stock solution was put in a long 

cylinder and the pipette filled by capillary 

action. When the level of the solution in the 

cylinder went down, more was added from the 

original solution. A glass rod was used to ensure mixing of the toxicant. The concentration 

of each jar was noted by marking with a wax 

pencil on the logs of wood supporting the big 

jars or on the aluminum tank near each small 

jar.

OBSERVATIONS

Observations were recorded each 24 hours 

after the toxaphene was introduced. Readings 

were taken for 96 hours, showing the number of 

dead fish in each jar. Oxygen was tested each 

day from the day of introduction of toxaphene 

to the last day of the experiment. Samples for 

oxygen determination were taken from the controls and not always from the same jar each 

day. This does not show exactly the oxygen 

situation in all the jars. There is a greater 

chance for more oxygen in the jars that lost 

larger numbers of fish (died and removed) than 

jars with most of the fish still alive.

Unless a fish was completely dead, it was recorded as alive. Some fish, bluntnose minnows 

for example, rested at the bottom of the container with their backs down and appeared to be 

dead. The fish in such cases were touched with 

a glass rod; if they did not show signs of movement, they were recorded as dead. Dead fish 

were removed only once a day. Each day the 

dead fish were collected and burned. At the end 

of the experiment all treated fish, including 

those still alive, were disposed of in the same 

way.

ANALYSIS

From the mortality observed, the TL m 

(median tolerance limit) values were obtained. 

The TL m is "the concentration of the tested
material in a suitable diluent (experimental 

water) at which just 50 percent of the test 

animals are able to survive for a specified 

period of exposure" (American Public Health 

Association, 1960, p. 458).

On semilogarithmic paper, 3 cycles x 70 divisions, concentration of the toxicant was plotted 

against the mortality observed. Two points only 

were used, one point showing mortality above 

50 percent of the population and the other one 

below 50 percent. These two points were connected (see fig. 1). From this line the concentration which killed 50 percent of the population 

was obtained. In this example the 96-hour TL m 

for bluntnose minnows at 63° F. was found to be 

0.0088 p.p.m. In certain cases where the gap 

between the two points was big, for instance, 

goldfish at 63° F., the 72-hour TLm values 

were obtained but were considered rough.

Whenever there were sufficient data, the L 

LDso (the median lethal dose) was evaluated by 

a graphic method (Wilcoxon and Litchfield, 

1949). The does were plotted against the percent mortality on logarithmic-probability paper 

No. 3228. Tests showing 0 percent or 100 percent mortality were omitted. A straight line 

was drawn through the points, particularly those

0.05

0.04

0.03

0.02

p o.oi

< 0.0088

0.005

0.001

BLUNTNOSE MINNOW AT 63° F. 

IN 96 HOURS

TL m = 0.0088

10 20 30 37 40 

% MORTALITY

50 53 60

showing just less and just more than 50 percent 

mortality (fig. 2). The expected mortality at 

each concentration is then read from the 

straight line and compared with the observed 

mortality (table 2). These authors stated that 

if the chi square of the line is, less than the 

value of chi square given in table 2 for 

degrees of freedom, the data are not significantly heterogeneous, that is, the line is a good 

fit.

Since 0.0502 is less than 7.82, the line seems1 

to be a good fit. From this line (fig. 2) the concentration of the toxicant which kills 50 percent, 

of the population was read and the LD 50 was 

found to be 0.011 p.p.m.

In cases where there were only two points 

(above and below 50 percent mortality), LD50 

values were determined but they could not be 

checked statistically as the number of degrees 

of freedom equals 0.

1

2

5

10

20

30

40 

50 

60 

w 70

< 80

S? 

90

95

98

99

o.oo:

BLUNTNOSE MINNOW AT 63° F. IN 96 MRS.

-

-

-

G)^^-""^

0 

^~~^~O

-

-

o..^- "'"""1"""*^

LD5Q = 0.011

-

-

-

55 0.005 6.01 0.05 0.0

98

95

90

80

70

60 

50 

40 ,,

30 3

<t

20 fc 

o

10 3"

5

2

1 

9

CONCENTRATION

Figure 1. The 96-hour TLm for bluntnose minnows at 

63° F.

Figure 2. The 96-hour LD^Q for bluntnose minnows at 

63° F.
TABLE 2.--Chi-square test of the 96-hour LD50 for bluntnose minnows at 63° F.

Toxaphene 

concentration

Percentage mortality

Observed

37 

53

60 

70 

70

--

Expected

40 

59 

57 

65 

72

--

Difference

3 

4 

3 

5 

2

" -

Contribution to 

chi square

0.0036 

0.0060 

0.0035 

0.0100 

0.0020

0.0251

For the bluntnose minnows a third method of 

analysis was also used, the minimum normit 

chi square method (Berkson, 1955). The LD 50 

is 0.0092 p.p.m. which is quite close to the TL m 

and graphic LD^ values.

RESULTS

The three methods of analyzing the data gave 

very similar results in most cases when applied 

to the bluntnose minnow (table 3). At 24 hours 

at 53° F. none of the concentrations gave over 

22 percent mortality, and therefore the TL m 

and 0)50 values must be very approximate. At 

63° F. the mortality was spread over a wide 

range of concentrations with lower mortality 

sometimes appearing in higher concentrations. 

With such variation in the experimental data it 

can be expected that the estimates of the concentration at which 50 percent die is subject to 

considerable variation. Yet the three methods 

give quite comparable estimates except for the 

48-hour period. At 73° F. the 48-hour TL m and 

normit LD50 values do not agree very well. 

This results from the use of only two points in 

each case, and the two points used were not the 

same.

The normit method was used only with the 

bluntnose minnow. In several situations with

TABLE 3. TLj, and LDjo values for bluntnose minnows at three temperatures.

At 53° F:

At 63° F:

At 73° F:

 4n

0 0088

LD5

Graphic

0 0088

0

Normit

other species the graphic LD 50 method could 

not be used because mortality rates both above 

and below 50 percent, but not 0 or 100 percent, 

were not available. In all other cases the TL m 

and LD 50 values were quite similar.

Berkson (1950) used eight different methods 

for the estimation of the LD 50 and found that all 

gave about the same results. Since the three 

methods used here gave close results in most 

cases, only the TL m data are discussed 

table 4).

CHANGE WITH TIME

It can be anticipated that fish can survive 

higher concentrations of a toxicant for short 

periods of time than they can for longer 

periods. As expected, in most of the tests 

(table 4) the TL m values decreased with time; 

in some cases the TL m remained constant, for 

instance the 72-hour and 96-hour TLm of the 

golden shiner at 73° F. and of the goldfish at 

53° F. and 63° F., and the 48-hour, 72-hour, 

and 96-hour TL m of the goldfish at 73° F. 

Henderson and Tarzwell (1957) stated that experience with a variety of industrial effluents 

has shown major difference in 24- and 48-hour 

TL m values, although there was little or no 

difference in the 48- and 96-hour values, except 

for an occasional effluent which produced fish 

mortality over the longer period.

Pickering et al (1962) when examining the 

acute and chronic or accumulative toxicity of 

Delnav to fathead minnows, found that TL m

TABLE 4. Ifedian tolerance limits (TL^,) to toxaphene for six species of fishes 

at three temperatures.

Species and temperature

Rainbow trout: 

At 53° .......................

Stoneroll rs: 

At 53° .......................

Goldfish: 

At 53® F

Golden shiner:

Bluntnose minnow: 

At 53° F

Black bullhead:

Concentration in p. p.m. for--

24 hrs.

0.03

0.062 

0.028 

0.054 

0.009

0.27 

0.086 

0.054

0.0125 

0.027 

0.0134

>4.0 

0.2

0.015

>0.048 

0.015 

0.012

48 hrs.

0.01A5

0.027 

0.0086 

0.044 

0.0078

0.115 

0.035 

0.05

0.007 

0.0066

0.86 

0.035 

0.0084

>0.048 

0.0043 

0.0042

72 hrs.

0.0111

0.027 

0.008 

0.035 

<0.005

0.094 

0.028 

0.05

0.0062 

0.006

0.15 

0.01A 

0.0065

0.034 

0.0042

0.003

96 hrs.

0.0084

0.01A 

0.0066 

0.032 

<0.005

0.094 

0.028 

0.05

<0.005 

0.006

0.03 

0.0088 

0.0063

0.025 

0.0027 

0.0018
values decreased (toxicity increased) rapidly 

for the first 5 days and less rapidly for the 

next 10 days. They did not notice any further 

decreases in TL m values during the additional 

15 days of exposure.

CHANGE WITH TEMPERATURE

With increase in temperature the rate of 

metabolism is higher and the toxicant is expected to be more effective. This was very 

clear in the case of the black bullhead and the 

bluntnose minnow which showed rapid decrease 

in TLm with increase in temperature. The goldfish showed rapid decrease in TL m with increase in temperature from 53° F. to 63° F. 

At 73° F. the 24-hour TLm went down and then 

kept constant at the 48-hour, 72-hour, and 96- 

hour TL m values higher than those at 63° F.

The golden shiner and the sonteroller showed 

decrease in TL m with change in temperature 

from 63° F. to 73° F. When temperature was 

changed from 53° F. to 63° F., the 24-hour TL m 

of the golden shiner was higher at 63° F. than 

at 53° F. The 24-hour TL m of the stoneroller 

at 53° F. was higher in one test when compared 

with the TL m at 63° F. and lower in the other. 

Both experiments of stoneroller at 53° F. were 

lower in 48-hour, 72-hour, and 96-hour TL ms 

than the equivalent TL m at 63° F. These variations in results indicate tests which should be 

repeated.

SPECIES COMPARISONS

Toxaphene was highly toxic to fish with 96- 

hour TLm values below 0.1 p.p.m. in all the 

tested cases. Henderson et al. (1959) gave 

TL ms of four species of fish to toxaphene 

(table 5). Their results for the fathead minnow 

are very similar to ours for bluntnose minnows 

(table 4). The TL m values for goldfish are 

somewhat different, but the TL m values for

TABLE 5. Ifedian tolerance limits (TI^) to toxaphene at 77° F. for four 

species of fish.

[From Henderson et al., 1959, p. 27]

Fish

Fatheads.. 

Do...... 

Bluegills.

Toxaphene, 

standard,

reference 

100-percent 

ne, diluted in 

Tim (p.p.m.) at 

24 hrs.

0.013 

.016 

.0075 

.0082 

.042

48 hrs.

0.0075 

.0075 

.0038 

.0068 

.024

96 hrs.

0.0075 

.0051 

.0035 

.0056 

.020

goldfish at 73° F. (table 4) have already been 

questioned. When they used BHC insecticide at 

77° F. they found the 24-, 48-, and 96-hour 

TL m for the fathead to be 22, 16, 15 p.p.m. 

respectively and for the goldfish 26, 21, and 15 

p.p.m.

When comparing the action of toxaphene in a 

period of 24 hours, the bluntnose minnow at 

53° F. seemed to be the most tolerant of all the 

tested species. These fish settle on their backs 

and remain in a half-dead state thus tolerating 

high doses of the toxicant. The goldfish ranked 

second, followed by the stoneroller, black bullhead, rainbow trout, and golden shiner. At 

63° F. the black bullhead was more sensitive 

than the golden shiner, whereas the others 

ranked the same as at 53° F. (no data on the 

rainbow trout). At 73° F. the goldfish showed 

higher TL m than the bluntnose minnow, followed 

by the golden shiner, the black bullhead, and 

the stoneroller.

In comparison of the 96-hour TLm at 53° F., 

the goldfish was the most tolerant, followed by 

the bluntnose minnow, black bullhead, and 

stoneroller, with the rainbow trout as the most 

sensitive (no data on the golden shiner). At 

63° F. the stoneroller was the most tolerant, 

leaving the goldfish in the second rank, followed by the bluntnose minnow, black bullhead, 

and golden shiner. At 73° F. the goldfish appeared to be the most tolerant, followed by the 

bluntnose minnow, golden shiner, black bullhead, 

and stoneroller.

In general, it seemed that the goldfish was 

the most tolerant of the tested fish to toxaphene, 

realizing that the bluntnose minnow at 53° F. 

showed higher TLm in the first 72 hours.

This apparent high tolerance of the bluntnose 

minnow in the first 3 days was due to the fact 

that they remained on their backs, but still half 

alive, for some time after being affected. If the 

half-dead fish had been considered dead, the 

TLm values would probably have been lower 

than those of the goldfish, which died quicker. 

The other species seem to be about equally 

sensitive to toxaphene and cannot be readily 

ranked.
OXYGEN

Aeration of the water was not consistent 

enough for the experiments to be comparable 

with respect to dissolved oxygen. Dissolved 

oxygen recorded at the beginning of the experiments (24 hours after the fish were put in the 

jars) varied from 5.9 to 8.0 p.p.m. at the 53° F., 

from 4.8 to 6.2 at 63° F., and from 3.2 to 6.0 

p.p.m. at 73° F. More consistent results might 

have been secured if all experiments had been 

started with dissolved oxygen near saturation.

In four experiments (stoneroller at 73° F., 

bullhead at 73° F., and bluntnose minnow at 

53° F. and at 73° F.), the recorded dissolved 

oxygen increased at least 1 p.p.m. sometime 

during the experiment, a situation which is difficult to explain.

The dissolved oxygen was below 3 p.p.m. at 

the end of the first 24 hours in the goldfish 

experiments at 53° F. and 73° F., the two experiments with the highest loading capacity, 2 

grams per liter. It was also below this level 

for the stoneroller at 63° F. and for all 73° F. 

experiments except the bluntnose minnow. While 

minimal oxygen requirements of fish are subject to many factors such as temperature and 

carbon dioxide content, the dissolved oxygen, if 

at the recorded values, was probably low 

enough to seriously affect the experimental 

fish. The Aquatic Life Advisory Committee of 

the Ohio River Valley Water Sanitation Commission states (1955, p. 327):

The dissolved oxygen content of warm water fish 

habitats shall be not less than 5 p.p.m. during at 

least 16 hr. of any 24-hour, period. It may be less 

than 5 p.p.m. for a period not to exceed 8 hr. within 

any 24-hr, period, but at no time shall the oxygen 

content be less than 3 p.p.m. To sustain a coarse 

fish population the dissolved oxygen concentration 

may be less than 5 p.p.m. for a period of not more 

than 8 hr. out of any 24-hr, period, but at no time 

shall the concentration be below 2 p.p.m.

Rounsefell and Everhart (1953) mentioned 

that the 5 p.p.m. oxygen tolerance limit is too 

high and listed minimum oxygen requirements 

as low as 0.38 p.p.m. for largemouth bass, 

0.2-0.3 p.p.m. for black bullhead, and below 

0.2 p.p.m. for golden shiner.

The fact that no fish died in the controls 

indicates that oxygen deficiency in itself was 

not a direct cause of mortality.

SUMMARY

Experiments were run at the Fish Control 

Laboratory, Bureau of Sport Fishery and Wildlife, La Crosse, Wis., in the summer of 1962, 

to determine the mortality of the stoneroller, 

golden shiner, goldfish, black bullhead, and 

bluntnose minnow to toxaphene in water at 

53° F., 63° F., and 73° F. A sixth species, 

rainbow trout, was tested at 53° F. only.

At the start of testing, all fish were in good 

health and showed no disease or abnormalities; 

fish were not fed during the experiments. 

Deionized water was reconstituted to give a 

standard water with specified characteristics. 

Air was run in the reconstituted water for 24 

hours before the start of an experiment. A reliable temperature control device was used to 

ensure constant temperature. Fish were introduced into jars to acclimatize for 24 hours before treatment with various concentrations of 

toxaphene. Mortality of fish was recorded every 

24 hours for 4 days. Untreated controls were 

used in each experiment.

TLm and LD^ were obtained by graphic 

methods to get the concentrations which will 

kill 50 percent of the population. A normit 

method was used with the bluntnose minnow data 

only for comparison. The three methods gave 

similar results. In most experiments, concentrations of toxaphene needed to cause 50 percent mortality decreased as the length of exposure increased from 24 to 96 hours, and decreased as temperature increased from 53° F. 

to 63° F. and to 73° F. Dissolved oxygen did 

not show consistent results and was below 3 

p.p.m. in several tests. At 96 hours the TL m 

values were below 0.1 p.p.m. of toxaphene in all 

species, indicating that fish are quite sensitive 

to toxaphene.

In general, goldfish was the most tolerant of 

the species tested with the other species showing similar enough sensitivity that they cannot
be effectively ranked with these data. Bluntnose 

minnows remained half dead much longer than 

other species, and thus the TL m values for the 

first 3 days at least may be somewhat high. 

Running experiments for longer periods of time 

is suggested. Narrower ranges of concentrations with several intermediate concentrations 

can be used in further tests now that the general range has been determined.

REFERENCES

American Public Health Association, American Water 

Works Association, and Water Pollution Control Federation.

1960. Standard methods for examination of water and 

waste water including bottom sediments and sludges. 

American Public Health Association, New York.

Berkson, J.

1950. Some observations with respect to the error of 

bioassay. Biometrics, vol. 6, p. 432-434.

1955. Estimate of the integrated normal curve by 

minimum normit Chi-square with particular reference to bio-assay. Journal of the American 

Statistical Association, vol. 50, p. 529-549.

Cohen, J. M., L. J. Kamphake, A. E. Lemke, C. Henderson, and R. L. Woodward.

1960. Effect of fish poisons on water supplies. Part 

I, Removal of toxic materials. Journal of American 

Water Works Association, vol. 52, p. 1551-1566.

Douglas, N. H., and W. H. Irwin.

1962. Evaluation and relative resistance of sixteen 

species of fish as test animals in toxicity bioassays 

of petroleum refinery effluents. Mimeographed.

Oklahoma State University, Department of Zoology, 

Contribution 351.

Fukano, Kiyoshi G., and Frank F. Hooper.

1958. Toxaphene (chlorinated camphene) as a selective fish poison. Progressive Fish Culturist, vol. 

20, p. 189-190.

Henderson, C., Q. H. Pickering, and C. H. Tarzwell.

1959. Relative toxicity of ten chlorinated hydrocarbo 

insecticides to four species of fish. Transactions o: 

the American Fisheries Society, vol. 88, No. 1, 

p. 23-32.

Henderson, C., and C. M. Tarzwell.

1957. Bio-assays for control of industrial effluentr. 

Sewage and Industrial Wastes, vol. 29, p. 1002-101^

Negherbon, William O.

1959. Handbook of toxicology. Vol. 3, Insecticides. 

W. B. Saunders Co., Philadelphia. 854 p.

Ohio River Valley Water Sanitation Commission, Aquati 

Life Advisory Committee.

1955. Aquatic life water quality criteria, first progress report. Sewage and Industrial Wastes, vol. 27, 

p. 321-331.

Pickering, Q. H., C. Henderson, and A. E. Lemke. 

1962. The toxicity of organic phosphorous insecticide 

to different species of war-water fishes. Transactions of the American Fisheries Society, vol. 91, 

p. 175-184.

Rounsefell, G. A., and W. H. Everhart.

1953. Fishery science; its methods and application«> 

John Wiley and Sons, New York.

Wilcoxon, F., and J. T. Litchfield, Jr. 

1949. A simplified method of evaluating dose-effect 

experiments. Journal of Pharmacology and Experimental Therapeutics, vol. 96, p. 99-113.

10
INVESTIGATIONS IN FISH CONTROL

7. Treatment of East Bay, Alger County, Michigan 

with Toxaphene for Control of Sea Lampreys

By William E. Gaylord, Biological Field Station, Ludington, Mich. 

and Bernard R. Smith, Biological Field Station, Marquette, Mich. 

Bureau of Commercial Fisheries

U.S. DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife 

Resource Publication 11 

Washington . January 1966
CONTENTS

Page 

Abstract..........................'.............. 3

Study area. ...................................... 3

Pretreatment surveys............................... 4

Bioassays with toxaphene ............................ 5

Application of chemicals ............................. 5

Immediate effects of the toxicant. ....................... 6

Posttreatment surveys .............................. 6

References ...................................... 6

FOREWORD

Application of toxaphene to East Bay had the approval of the Michigan 

Department of Conservation and of local inhabitants who were advised on 

the project in public hearings. The Bureau of Commercial Fisheries and 

the Great Lakes Fishery Commission, after this single experiment, 

abandoned the use of toxaphene in the program for control of the sea 

lamprey. It is believed that certain of the observations in East Bay are 

of sufficient interest to warrant publication of this report. This study was 

part of a program conducted by the Bureau of Commercial Fisheries 

under contract with the Great Lakes Fishery Commission.
TREATMENT OF EAST BAY, ALGER COUNTY, MICHIGAN, 

WITH TOXAPHENE FOR CONTROL OF SEA LAMPREYS

By William E. Gaylord, Biological Field Station, Ludington, Mich.

and Bernard R. Smith, Biological Field Station, Marquette, Mich.

Bureau of Commercial Fisheries

Abstract. An experiment was conducted to determine whether toxaphene 

can be used to eradicate lake-dwelling sea lampreys and to determine its 

effect on fish populations. In East Bay, a 78-acre lake on the Sucker River, 

Alger County, Mich., an estimated concentration of 100 parts per billion 

was maintained for 14 days. The sea lamprey larvae were more resistant 

to toxaphene than were the fish, but a complete kill was indicated. One 

year after treatment, sea lampreys were absent from the lake, while the 

fish population had recovered.

The Bureau of Commercial Fisheries' program for control of the sea lamprey (Petromyzon marinus) in the Great Lakes has progressed rapidly with the development of lamprey 

larvicides (Applegate et al., 1961). Success of 

chemical control depends on treatment of all 

populations of ammocetes in the streams and 

lakes tributary to the Great Lakes.

The selective lampricide now being used has 

proved successful in streams and rivers, but 

its relatively high cost prohibits use in the 

larger estuarine bodies and lakes in river systems. In many of these a general toxicant can 

be used without permanent damage to fish populations. Several chemicals are readily available at nominal cost.

Toxaphene (chlorinated camphene) has been 

used widely as an agricultural insecticide; it 

has been used to some extent as a fish toxicant, 

but no reference could be found to its effect on 

lampreys. Hooper and Grzenda (1957) stated 

that 0.05 p.p.m. of emulsified toxaphene is 

sufficient for fish eradication. They also demonstrated that the substrate influences the rate 

of detoxification of the material. Hooper and 

Fukano (1960) observed a slowdown in fish

mortality with falling temperatures, particularly at values below 50° F.

An experiment to test the feasibility of using 

a commercial formulation of toxaphene was 

planned for 1961. The site selected was East 

Bay, a small lake in the lower end of the Sucker 

River, 2 miles east of Grand Marais, Alger 

County, Mich. The Sucker River had been 

treated with selective larvicide in 1958 and 

1959. The toxaphene formulation used was 

Cooper-Tox No. 6 (toxaphene emulsifiable 

concentrate).

STUDY AREA

East Bay is a 78-acre lake formed by low, 

shifting sand dunes on the shore of Lake Superior (fig. 1). The margin of the lake has a narrow, shallow-water shelf beyond which water 

depth drops abruptly to 20-30 feet. The bottom 

is primarily sand; some limited areas have 

bottoms of soft mud and silt. The Sucker River 

flows into the southeast end of East Bay. The 

outlet is on the west side into West Bay, which 

is connected directly to Lake Superior. The 

inflow averages approximately 85 c.f.s., but it 

varied from 80 to 200 c.f.s. during the treatment period.
O LIMNOLOGICAL STATION 

 CAGED AMMOCETES

Figure 1. Map of East Bay showing location of ammocete cages, limnological stations, and the application site in the

Sucker River.

East Bay was not stratified thermally in the 

fall of 1961. Water temperatures varied from a 

maximum of 49° F. to a minimum of 42° F.; the 

difference between the surface and the bottom 

was nil to 2.5° F. (table 1).

Dissolved oxygen remained high (8.9 to 10.2 

p.p.m.) during the period of observation. The 

hydrogen-ion concentration varied from pH 7.5 

near the bottom to 9.5 near the surface.

PRETREATMENT SURVEYS

Pretreatment surveys with electric shockers 

had demonstrated the presence of sea lamprey 

ammocetes in large numbers in East Bay. The 

greatest concentrations were on the alluvial fan 

formed by the Sucker River. The size of the 

population was estimated at 96,000 individuals 

(Wagner and Stauffer, 1962). Ammocetes were 

found also in the connecting channel between

East and West Bays and in West Bay in the 

immediate area of the mouth of the channel.

A riffle fyke net fished in the channel between 

East Bay and West Bay from March 15 to October 24, 1961, captured 278 sea lampreys (9 

transformed individuals and 269 larvae) and 

220 American brook lamprey larvae. These 

data supported the view that a large population 

remained in the lake, although the Sucker River 

had been successfully treated with selective 

larvicide in 1959.

TABLE 1. Water temperatures (°F.) in East Bay, October-November 1961

Depth

Surface....

20 feet.. 

30 feet..

Bottom1 ....

October 4, 

at station 

1

49.0

47.2 

46.5

46.5

2

49.4

48.2 

47.0

47.0

October 25, 

at station--

1

45.0

45.0

2

45.0

45.0

November 1, 

at station 

1

43.0

43.0

2

43.0

43.0

November 6, 

at station 

1

42.0

42.0

2

42.0

42.0

1 39 feet at station 1, 34 feet at station 2.
Tows, totaling 43 minutes trawling time, with 

an electric beam trawl at several stations in 

East Bay in August 1961 captured 52 sea lampreys and 44 American brook lampreys. September 20-22, 151 minutes of trawling in West 

Bay yielded 16 sea lampreys and 14 brook lamprey larvae. All were captured near the mouth 

of the channel connecting the two bays.

The fish population was sampled immediately 

before the treatment by sets of gill nets at 7 

locations. Each set included four 125-foot nets 

with 25-foot sections of 1-1/2-, 2-, 2-1/2-, 3-, 

and 4-inch mesh (extended measure). The catch 

in 7 nights of fishing was 27 rainbow trout, 8 

northern pike, 41 white suckers, 47 yellow 

perch (all less than 6 inches long), and a few 

individuals of 6 other species, to bring the total 

to 141 fish (table 2).

TABLE 2. Number of fish, by species, taken from East Bay before and after 

poisoning with toxaphene

TABLE 3. Results of bioassays with toxaphene on lamprey ammocetes, 

October 1961

[Temperature, 58°-66° F.]

Species

Rainbow trout:

Less than 12 inches ...... 

White sucker:

Before treatment 

(October 5-11, 1961)

Total 

number

24 

3

30 

11

8 

6 

47

1 

5 

2 

3

I 

0 

0 

0

141

Number per 

1,000 feet 

of net

6.9

0.9

8.6 

3.1

2.3 

1.7 

13.4 

0.3 

1.4 

0.6 

0.9 

0.3 

0.0 

0.0 

0.0

40.3

After treatment 

(October 23-25, 1962)

Total 

number

4 

34

11 

9

2

1 

3 

0 

0 

0 

0 

0

1

2

1

68

Number per 

1,000 feet 

of net

2.7 

22.7

7.3 

6.0

1.3 

0.7

2.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.7 

1.3 

0.7

45.3

BIOASSAYS WITH TOXAPHENE

Bioassays were conducted, at the Bureau's 

Hammond Bay Biological Station, of various 

concentrations of toxaphene to test the effect of 

the material on lamprey larvae. The laboratory 

tests indicated that, to be killed in a reasonable 

time (15 to 20 days), ammocetes should be exposed to a concentration of at least 80 p.p.b. 

(table 3). Because lack of time prohibited more 

extensive study, a concentration of 100 p.p.b. 

was chosen for the treatment.

Size of test 

container

Concentration 

of toxaphene

P.p.b.

50

40

80

Exposure 

time

Days

17

19

16

9

12

Mortality

Percent

4

10

100

40

100

APPLICATION OF CHEMICALS

The Sucker River was re-treated with the 

selective larvicide 3-trifluoromethyl-4-nitrophenol (TFM), October 19-22, 1961, to prevent 

immediate recontamination of East Bay by 

young lampreys from upstream.

Treatment of East Bay with toxaphene began 

on October 24. Eighty-five gallons of this toxicant, the amount needed to give a concentration 

of 100 p.p.b. through the entire volume, were 

distributed systematically over the surface of 

the lake. Simultaneously, toxaphene was added 

(by means of a portable fuel-pump feeder 

Anderson, 1962) into the river above East Bay 

at a rate to produce 100 p.p.b. in the water entering East Bay. This pump operated continuously for 14 days.

Eleven days after the distribution of toxaphene began, 5 more gallons were applied to 

the surface of a small backwater at the southeast end of the lake and to the shoreline on the 

east end of the lake. A few ammocetes had been 

observed swimming in those areas the previous 

day.

Before treatment, 10 lamprey larvae were 

placed in each of 15 cages (11 cages in East 

Bay, 2 in the connecting channel to West Bay, 

and 2 in West Bay near the mouth of the channel fig. 1). The condition of these larvae and 

the number dead were recorded at intervals 

from October 22 until November 26, when cold 

weather forced termination of observation.

Equipment was not available for quantitative 

determination of toxaphene during this experiment. Assuredly, it would have been advantageous to know the toxaphene concentration at
different intervals after application. The work 

of others would seem to indicate that concentrations reached may have been considerably 

less than those desired (Kallman, Cope, and 

Navarre, 1962).

IMMEDIATE EFFECTS OF THE TOXICANT

Small fish were observed surfacing and dying 

the day after treatment began. Mortality of fish 

increased daily, reached a peak during the third 

and fourth days, and ended shortly after. The 

area was kept under observation during the 

treatments, and estimates were recorded of the 

number and species of dead fish. These estimates were biased by recovery of fish by 

fishermen. Approximately 50 to 80 large rainbow trout (more than 12 inches long) and 25 

northern pike were the only game fish of 

appreciable size observed. Yellow perch were 

killed in large numbers (3,000 to 4,000), but 

almost none were over 6 inches long. Several 

hundred white suckers, several thousand minnows, and a few small rainbow trout, round 

whitefish, walleye, burbot, and rock bass were 

seen.

The first dead larval lampreys were seen on 

the fourth day after treatment began. Their 

numbers were small in relation to the estimated size of the population.

Ammocetes were slow to emerge from the 

mud in the bottom of the test cages. Only a few 

individuals in each container in East Bay had 

appeared by the end of 4 days. All specimens 

had emerged by the sixth day and approximately 

one-third were dead. Most of the remainder 

were near death.

After emergence from the bottom, some 

larval lampreys swam aimlessly for a short 

time, but most lay contorted on the bottom and 

gave only an occasional twitch. They remained 

in this condition to the end of the daily observations. Many lampreys gave indications of 

hemorrhage around the gills, sides, and anus. 

All ammocetes showed loss of pigmentation.

Daily observations of the caged lampreys 

were continued for 14 days. During this period, 

6 cages were lost in storms. Of the original 90 

specimens in the remaining 9 cages, all in 4

cages were dead and 33 in 5 cages were alive 

at the end of 14 days. Observations were terminated at the end of 36 days of exposure. Two 

ammocetes were then still alive.

POSTTREATMENT SURVEYS

A riffle fyke net, fished in the connecting 

channel between East and West Bays after the 

treatment until November 30, captured no lamprey ammocetes. It was reset in the same location March 15 and fished without interruption 

until November 26, 1962. During this period, 

only 1 American brook lamprey ammocete was 

taken.

The electric beam trawl was dragged in East 

Bay in May and August 1962, for a total towinir 

time of 113 minutes. No lampreys were taken. 

Trawling in West Bay near the mouth of the 

channel in 1962 yielded 7 ammocetes (5 sea 

lampreys and 2 American brook lampreys) in 

79 minutes.

It is evident from these data that toxaphene 

brought about nearly complete eradication of 

ammocetes in East Bay. The two test animals 

that were still alive 36 days after treatment 

indicated that mortality may not have been 

complete, but it is probable that larvae not 

dead at the end of the treatment period had 

received a lethal dose and subsequently died.

The fish population was sampled again 1 yeai 

after the experiment to determine the extent of 

recovery from the toxaphene. Nets fished 1 

night at each of three 1961 locations captured 

68 fish, including 4 rainbow trout over 12 

inches, 2 northern pike, and 20 white suckers 

(table 2). The population of yellow perch was 

sharply lower than a year earlier, but the nunber of immature rainbow trout had increased.

REFERENCES

Anderson, Gaylord A.

1962. Three portable feeders for metering chemical 

into streams for control of sea lamprey. Progressive Fish-Culturist, vol. 24, No. 4, p. 190-192.

Applegate, Vernon C., John H. Howell, James W. Moffett, 

B. G. H. Johnson, and Manning A. Smith. 

1961. Use of 3-trifluormethyl-4-nitrophenol as a selective sea lamprey larvicide. Great Lakes Fisher) 

Commission, Technical Report 1. 35 p.
Hooper, Frank F.t and Alfred R. Grzenda.

1957. The use of toxaphene as a fish poison. Transactions of the American Fisheries Society, vol. 85 

(1955), p. 180-190.

Hooper, Frank F., and Kiyoshi G. Fukano.

1960. Summary of experimental lake treatments with 

toxaphene 1954-1958. Michigan Department of Conservation, Institute for Fisheries Research, Report 

1584. 17 p. [Mimeographed.]

Kallman, Burton J.t Oliver B. Cope, and Richard J. 

Navarre.

1962. Distribution and detoxification of toxaphene in 

Clayton Lake, New Mexico. Transactions of the 

American Fisheries Society, vol. 91, No. 1, 

p. 14-22.

Wagner, Wilbert C., and Thomas M. Stauffer.

1962. Sea lamprey larvae in lentic environments. 

Transactions of the American Fisheries Society, 

vol. 91, No. 4, p. 384-387.

INVESTIGATIONS IN FISH CONTROL

8. Effects of Toxaphene on Fishes and Bottom Fauna 

of Big Kitoi Creek, Afognak Island, Alaska

By William R. Meehan and William L. Sheridan 

Alaska Department of Fish and Game

U.S. DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service 

Bureau of Sport Fisheries and Wildlife 

Resource Publication 12 

Washington . January 1966
CONTENTS

Page

Abstract. ....................................... 3

Study area. ...................................... 4

Methods ........................................ 5

Fish ......................................... 5

Bottom fauna ................................... 5

Application of toxaphene............................ 5

Results. ........................................ 6

Fish ......................................... 6

Bottom fauna ................................... 6

Detoxification and recovery of creek. ................... 7

Discussion ...................................... 7

Summary ....................................... 8

References ...................................... 8
EFFECTS OF TOXAPHENE ON FISHES AND BOTTOM FAUNA OF 

BIG KITOI CREEK, AFOGNAK ISLAND, ALASKA

By William R. Meehan and William L. Sheridan 

Alaska Department of Fish and Game

Abstract. Big Kitoi Creek, on Afognak Island, Alaska, was treated with 

toxaphene in July 1961 to remove sculpins predaceous on pink salmon fry. 

Dispersion and penetration of toxaphene into the streambed were determined, as well as time required for detoxification. The population of sculpins in the creek before treatment was estimated at 30,000, of which 82 

percent were in the size range considered predaceous on pink salmon fry. 

Extent of predation was determined by examination of stomachs of 180 

sculpins. Considering the rate of predation, it was estimated that, of 

847,500 ± 418,600 fry in the gravel 3 months before treatment, 12 percent 

may have been eaten by sculpins before the fry migrated to salt water. 

Bottom fauna decreased in numbers and weight after the toxaphene treatment: insects were completely eradicated; some other invertebrate 

groups were not completely eliminated. Posttreatment recruitment of bottom fauna began later in the summer; a year later the pretreatment levels 

of biomass had not yet been reached. Species composition of bottom fauna 

a year after treatment differed somewhat from that before treatment. 

Assuming that, if the creek had not been treated, 30,000 sculpins would 

have been present in the spring of 1962, then the treatment possibly saved 

approximately 135,000 pink salmon fry in 1962.

Pink salmon (Oncorhynchus gorbuscha) and 

chum salmon (O. keta) deposit their eggs in the 

gravel of coastal streams in Alaska from July 

to October. Eggs incubate through the winter, 

and fry migrate into salt water the following 

spring. During downstream migration, fry of 

both species are from 26 to 36 millimeters 

long and are subject to predation both in streams 

and in estuaries.

Since pink and chum salmon go to sea almost 

immediately after they emerge from streambed gravels, they usually are not dependent on 

a food supply while in fresh water. Coho salmon 

(O. kisutch), on the other hand, remain in fresh 

water for 1 or 2 years before going to sea;

Present address of the authors: U.S. Forest Service, 

Box 1631, Juneau, Alaska.

hence, the food supply may sometimes limit 

their survival.

The coastrange sculpin (Cottus aleuticus) is 

one of the chief predators on salmon fry in 

fresh-water streams. Because there were large 

numbers of C. aleuticus as well as an annual 

run of several thousand pink salmon in Big 

Kitoi Creek, a study was carried out in 1961 

and 1962 to determine (1) the extent of predation by sculpins on pink salmon fry, (2) the 

effects of toxaphene on the sculpins, and (3) the 

effects of toxaphene on the bottom fauna.

If predation by sculpins was significant, 

eradication of the sculpin population would 

relieve downstream migrant pink salmon fry of 

this cause of mortality. If the bottom fauna was 

at the same time eradicated, and the rate of
recovery was slow, production of resident fish 

such as coho salmon and trout would be limited.

Predation by sculpins probably depends on 

the species of sculpin and availability of salmon 

fry. Bailey (1952) reported that food studies on 

Cottus bairdi by Ricker (1934), Koster (1937), 

and Dineen (1951) indicated that this species 

was not a serious game fish predator. Bailey's 

study of Cottus bairdi in Montana agreed with 

these findings. On the other hand, Robertson 

(1949) reported that sculpins (species not mentioned) exacted the greatest toll of sockeye 

salmon fry migrating from tributary streams 

into Port John Lake in British Columbia. One 

sculpin, 4-1/2 inches long, contained 38 fry, 

and the average was 13 fry per sculpin. Pritchard (1936) determined that the average consumption of salmon fry by sculpins in McClinton 

Creek in British Columbia for 1931 and 1933 

respectively was 0.8 and 1.5 fry per sculpin. 

Hunter (1959) determined that in Hooknose 

Creek, Port John, British Columbia, C. aleuticus and C. asper fed almost exclusively on pink 

and chum salmon fry during downstream migration. Hunter calculated that numbers of pink 

and chum fry consumed by sculpins alone (1948 

to 1957) ranged from 73,868 in 1950 to 276,833 

in 1948. Hikata and Nagasawa (1960) reported 

that of 442 C_. nozawae stomachs examined in 

Memu Stream, Tokachi River system, 5.4 percent contained salmon fry. Patten (1962) reported on predation upon coho salmon fry by 

C. perplexus and C. rhotheus. Hence, where 

fresh-water sculpins have access to salmon 

fry, they can be serious predators. In years 

when few pink salmon fry are produced in a 

stream a greater proportion would be eaten, 

perhaps enough to keep a low spawning run depressed (Neave, 1953).

STUDY AREA

Big Kitoi Creek originates at the outlet of 

Big Kitoi Lake, a 356-acre lake on Afognak 

Island, Alaska (fig. 1). The creek flows approximately 2,000 feet before it enters salt water; 

only the lower half of the stream is accessible 

to anadromous fishes, because two falls prevent passage. Average gradient of the stream 

below the falls is 2.3 percent, and the streambed consists of rocks up to 18 inches in diamFigure 1, Location of study area, Afognak IslandAlaska.

eter. At least 80 percent of the particles comprising the streambed are larger than 3 

millimeters. The stream averages 20 feet in 

width and is from 1 to 3 feet deep during normal water conditions.

The stream was marked off in 100-foot sections for sampling, with section I at the mouth 

and section 10 ending immediately below the 

first falls. Only 700 feet proved to be usable for 

the bottom fauna study (sections 3 through 9), 

since the lower two sections were saline and 

section 10 was too swift. Section 3 was flooded 

at each high tide; tidal influences were also 

observed in section 4, and at extremely high 

tides in section 5. Above section 5, the streair 

narrowed and was swifter than in the lower 

sections.

In addition to sculpins and pink salmon, 

other fishes in Big Kitoi Creek in varying numbers and at intervals were Dolly
Varden (Salvelinus malma), threes pine stickleback (Gasterosteus aculeatus), coho salmon, 

rainbow trout (Salmo gairdneri), and to a much 

lesser extent sockeye salmon (O. nerka), 

crescent gunnel (Pholis laeta). and smelt 

(Osmeridae).

METHODS

FISH

The population of sculpins in Big Kitoi Creek 

before poisoning was estimated in two ways: 

(1) By flushing random 4-square-foot areas 

^vith an air-water jet directed into the streambed (McNeil, 1960) and dislodging sculpins into 

a collecting net, and (2) by tag and recovery. In 

"he latter case 255 sculpins were collected with 

,a 110-volt a.c. electroshocker, tagged, and 

 released back into the creek.

To evaluate the seriousness of predation in 

3ig Kitoi Creek, rate of digesting was first 

nudied by placing 37 sculpins in a glass aquar- 

: um, starving them for 24 hours (Darnell and 

" leierotto, 1962), then furnishing them with an 

abundance of pink salmon fry for a short time. 

Ttomachs from sculpins taken in the creek were 

examined, and condition of pink salmon fry 

compared with the laboratory specimens.

Extent of predation was studied by collecting 

' 80 sculpins with an electroshocker on May 10, 

11, and 12, 1961, and examining stomachs. 

During this period, downstream pink salmon 

fry migration was at its peak.

HOTTOM FAUNA

Bottom organisms were sampled periodically 

h ^fore and after toxaphene treatment by means 

c f a Surber square-foot bottom sampler. Three 

samples were taken in each section once a 

r^onth. The sampling sites were selected by 

use of a table of random numbers at the beginr ing of the study, and subsequent samples were 

taken adjacent to the initial sampling sites so 

t-at the same type of substrate was sampled 

each month in each section. These samples 

vere preserved in formal-alcohol for future 

a nalysis. Preservative was composed of equal 

F arts by volume of 70-percent ethyl alcohol and

5-percent formalin. Each sample was then 

sorted, the organisms were identified, and the 

number in each group was recorded. Later, the 

total fauna of each square-foot sample was 

blotted for 1 minute and immediately weighed 

on an analytical balance. Shells of live mollusks 

were included in the weights; empty shells and 

cases of Trichoptera larvae were not included. 

Weights were recorded to the nearest milligram. These data were later transferred to 

punchcards for tabulation.

APPLICATION OF TOXAPHENE

The stream was treated with toxaphene (Agricultural Cooper-Tox No. 6) on July 5 and 6, 

1961. At this time all pink salmon fry had migrated to sea, and returning pink salmon adults 

had not yet entered the creek.

Two 5-gallon cans of toxaphene were placed 

at the top of a 12-foot falls, immediately above 

Section 10, and were siphoned directly into the 

creek through a rubber tube and metered with 

an adjustable clamp. The rate of flow was determined by means of a graduated cylinder and 

stopwatch. Concentrations were calculated on 

the basis of amount of toxaphene mixed with 

known discharge (13.1 c.f.s.). Toxaphene was 

applied for 18.5 hours, with an average concentration of 1.5 p.p.m.

Immediately after treatment, all visible dead 

fish were counted in sections 3, 4, and 5. Some 

rocks were turned over and the streambed examined, because many sculpins remained under 

rocks after they had died.

Heavy concentrations of toxaphene caused 

water in the stream to turn a milky color. Although it appeared that thorough mixing was 

achieved, fluorescein dye was inserted at the 

treatment point to make mixing easier to observe. Observations of dye showed complete 

mixing from the falls to tidewater, even in 

small pools and backwater eddies.

To determine the extent of penetration of 

toxicant into streambed gravels, plastic 

standpipes were placed 7 or 8 inches deep at 

six cross-sectional stations. Vaux (1962) and 

Sheridan (1962) describe the interchange between surface stream water and water in the
gravel of the streambed. Based on these findings alone, we can assume penetration of toxicant into the gravel. In corroboration of the 

assumption, after dye was released upstream 

its presence was detected in samples of water 

withdrawn from the standpipes. Therefore, as 

assumed, diluted toxicant penetrated to a depth 

of at least 7 inches into the streambed.

Toxicity of stream water was evaluated by 

placing live fish (sculpins and salmonids from 

a nearby stream) in small wire-screen minnow 

traps up and down the stream and observing 

effects at periodic intervals during and after 

treatment.

RESULTS

FISH

Of the 255 sculpins tagged, 13 were recovered 

in a sample of 2,000 sculpins collected after 

poisoning. The population estimate by this 

method is then approximately 40,000 sculpins 

in the creek below the falls before poisoning. 

At approximately the same time 95-percent 

confidence limits for the population determined 

by hydraulic displacement were 37,957 ± 9,265. 

We feel that, based on the above population 

estimates, 30,000 sculpins is a reasonable 

estimate of the total number of sculpins in the 

stream. Of these 30,000, 82 percent fall in the 

size range 5.0 cm. to 11.9 cm. (based on a 

sample of 597 sculpins measured after treatment).

Sculpins maintained in the aquarium for determination of rate of digestion of pink salmon 

fry were reluctant to feed in captivity, but 

enough did eat so that when sacrificed at periodic intervals after feeding, condition of consumed fry could be determined. Seven hours 

after consumption, pink salmon fry were readily 

detectable as such. After 20 hours, fry were 

mostly a digested mass, almost unrecognizable 

as fish. This means that pink salmon fry 

(recognizable as such) found in sculpin stomachs in the morning were most likely eaten the 

preceding night.

Of 180 sculpins collected before poisoning, 

25 contained an average of 2.1 fry, or an overall

average of 0.14 fry per sculpin. The smallest 

sculpin (total length) which contained fry was 

2.7 cm. and the largest was 8.7 cm. We think 

that this example of consumption of a fry by a 

predator no larger than the prey was an isolated 

instance. Therefore, in the following calculations of extent of predation, this one instance is 

disregarded.

Using a method similar to that of Hunter 

(1959), we multiplied 30 days (duration of most 

intense pink salmon fry migration) x number of 

sculpins capable of consuming fry (24,600) x 

rate of predation (0.14) and found that 103,320 

pink salmon fry were possibly consumed by 

sculpins during the 1961 spring migration. Previously we estimated 847,500 + 418,600 fry in 

the gravel in March; hence, 12 percent of the 

mean estimated number of pink salmon fry may 

have been eaten by sculpins.

In addition to sculpins, other fish were observed dead as follows: Dolly Vardens, 43; 

rainbow trout, 3; coho fingerlings, 74; and 

gunnels, 6.

BOTTOM FAUNA

Bottom organisms decreased in number and 

weight after toxaphene treatment in July 1961 

(tables 1 and 2). Before treatment, the specie^ 

composition of Big Kitoi Creek bottom fauna 

changed rapidly as the influence of salt water 

decreased, or as areas further upstream were 

considered. The various species of midges 

(Tendipedidae), for example, made up a much 

larger part of the bottom fauna upstream than 

in sections 3 and 4 where tidewater influences 

were pronounced. Conversely, the brackishwater-inhabiting forms such as the amphipod^ 

and isopods decreased in relative abundance

TABLE 1. Number and weight of organisms per square foot before and af~.er 

poisoning

Section

Before poisoning 

(Spring 1961)

Number

336.0 

115.5 

134.6 

71.5

164.4

Weight 

(grams)

1.383 

0.310 

0.142 

0.167

0.501

After poisoning

Summer 1961

Number

94.6 

50.0 

77.8 

45.6 

33.0

7.8

50.7

Weight 

(grams)

0.414 

0.069 

0.287 

0.045 

0.121

0.016

0.136

Spring 1962

Number

156.9 

62.3 

33.7 

108.3 

134.2 

115.6 

66.2

96.8

Weight 

(grams

0.206 

0.082 

0.05'i 

0.18'i 

0.25:

o.ise

0.34f

0.18!
TABLE 2. Analysis of variance for difference in number and weight of 

organisms per square foot before and after treatment

[July to September]

Mean number of organisms 

per square foot:

Mean weight of organisms 

per square foot:

Degrees 

of 

freedom

1

58

Sum 

of 

squares

554 134

Mean 

square

144 327

F

15.6**

**Signifieant at 1 percent level.

with a similar transition to a. completely freshwater environment. Midges were the most important group throughout the stream; the 

crustaceans (Amphipoda and Isopoda) were 

also relatively abundant, although primarily 

in the intertidal sections.

Treatment of the stream with toxaphene had 

several effects on the bottom fauna. The insect 

groups succumbed completely and more rapidly 

than other invertebrates, such as clams and 

snails, which were the last groups to be affected 

and which were never completely eliminated. 

Although the July sampling showed a complete 

lack of live insects, the insects began to reinvade the stream later in the summer. Emergence of adult insects contributed to this 

elimination of insects in the July sampling, 

as evidenced by a few shed larval cases and 

pupal skins; however, most of the insects were 

killed before emergence. Amphipods and isopods in the intertidal sections were eventually 

completely eradicated, although these two 

groups were still present in the July sampling, 

indicating that they were more resistant. The 

upstream sections became barren of bottom 

fauna before the lower and intertidal sections.

DETOXIFICATION AND RECOVERY OF 

CREEK

Fish. Bioassay with coho and sockeye 

smolts, threespine stickleback, and sculpins 

showed that the stream became nontoxic after 

21 days. In addition, Dolly Vardens moved into 

the stream from salt water early in August and 

remained throughout the salmon spawning run.

Final evidence that Big Kitoi Creek became 

freejfrom toxicant in a short time was the success of pink salmon spawning in the stream 

after treatment. Pinks deposited eggs from 

August 25 until early October, 1961; hence, 

spawning first occurred 50 days after treatment. Sampling of eggs in the streambed in 

November 1961 revealed a very high survival, 

and subsequent sampling of preemergent fry in 

March 1962 gave a mean estimate of 1,124,000 

fry, or 44 percent egg-to-fry survival.

Bottom fauna. When initial recruitment of 

organisms began later in the summer, the upstream sections were the first to show an influx. This is probably due to the drifting in of 

organisms from the lake and stream above the 

falls area (Waters, 1961). The partially eradicated mollusk populations were the first to 

show a marked increase after treatment, and 

the insect groups were slowest to appear in 

quantity. One year later the pretreatment levels 

of biomass, in terms of weight and number of 

organisms per square foot of streambed, had 

not been reached. The species composition of 

the bottom fauna almost 1 year after treatment 

was somewhat different from that before treatment. The noninsect forms, including annelids, 

were the dominant forms throughout the study 

area, although the tendipedids were still the 

most numerous insect form. In the intertidal 

sections, annelid worms were abundant while 

the previously numerous amphipods and isopods were absent. The annelids were becoming 

reestablished in the most saline environment 

and were gradually expanding to the less saline 

areas. The mollusks (Gastropods, Pelecypoda), 

which were never completely eradicated, became established in greater magnitude after 

treatment but occupied the same general area 

as before treatment.

DISCUSSION

Results of treating Big Kitoi Creek with toxaphene show that this was an economical (cost 

of toxaphene for Big Kitoi Creek was $28) and 

effective way to control predation on salmon 

fry in this stream.

Although the method described in this report 

lends itself to eradication of undesirable fish in 

streams, it cannot be used where there are
resident populations of trout and/or salmon 

which should be maintained. Both the desirable 

fish and their food supply would be eradicated. 

On the other hand, there are streams in Alaska 

which support only pink and chum salmon and 

these streams are ideal for treatment. For 

example Noerenberg (1960) reported that in 

Prince William Sound pink and chum salmon 

comprise 90 percent of the run, sockeye salmon 10 percent. Coho salmon are of little importance and no known spawning runs of Chinook 

salmon (O. tshawytscha) or steelhead trout 

(Salmo gairdneri) exist.

Assuming that 30,000 sculpins would have 

been present in Big Kitoi Creek in the spring 

of 1962 if treatment had not occurred, it is 

possible that 12 percent, or approximately 

135,000 pink salmon fry, were saved in 1962 by 

the treatment.

SUMMARY

Part of Big Kitoi Creek, on Afognak Island, 

Alaska, was treated with toxaphene to determine (1) the extent of predation by sculpins on 

pink salmon fry in the stream, (2) the effects of 

toxaphene on the sculpins, and (3) the effects of 

toxaphene on the bottom fauna.

The estimated population of sculpins before 

treatment was 30,000. Approximately 100,000 

pink salmon fry could have been taken by sculpins in 1961. Treatment with toxaphene eliminated sculpins and other fishes in a 1,000-foot 

section of the stream. Sculpins were not observed up to 1 year later.

Insects were eliminated, and populations of 

other invertebrate forms were greatly reduced. 

Recruitment of bottom organisms began shortly 

after treatment, but 1 year after treatment the 

pretreatment levels of bottom fauna biomass 

had not been reached. In general, the various 

groups of organisms were reestablished in the 

same areas they inhabited before treatment; in 

a few cases major groups have been replaced 

by different forms which were less well represented before treatment.

In this case we feel that the treatment of Big 

Kitoi Creek with toxaphene was an economical 

and effective means of reducing predation on 

pink salmon fry.

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1962. Determination of feeding chronology in fishes 

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