An Investigation of Walleye Egg
Hatching Success in the
Lower Fox River, Wisconsin
liOSOL-.-Jc
... t i'.
Houghton, Ml 49931
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An Investigation of Walleye Egg
Hatching Success In the
Lower Fox River, Wisconsin
by
Nancy A. Auer
Research Scientist
Department of Biological Sciences
and
Martin T. Auer
Assistant Professor
Department of Civil Engineering
Michigan Technological University
Houghton, Ml 49931
A Research Project Supported by the
U.S. Environmental Protection Agency,
ERL-Duluth, Duluth, Minnesota
under Grant No. R810076010,
Nelson A. Thomas, Project Officer
DRAFT - SUBMITTED AS A PROGRESS REPORT
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Tab le £& Contents
I. Walleye In the Fox River and Green Bay
II. Fox River Water Quality In Relation to
the Wa11 eye Fishery
III. Importance of Selected Environmental
Factors for Hatching Success
A. Dissolved oxygen
B. Hydrogen sulfide
C. Sedimentation and substrate
IV. Materials and Methods
A. Fish and egg handling
B. Trap construction and placement
C. Fungi Identification and enumeration
D. Laboratory rearing experiments
E. Chemical analyses
F. Larval fish surveys*
G. Sediment analysis
V. Results and Discussion
VI. Summary and Conclusions
VII. AcknowIedgements
VIII. Literature Cited
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L 1st £i Tables
1. Commercial catch record for the lower Fox River and southern Green Bay#
1973-79.
2. Species composition of fyke net surveyss In the lower Fox River and
southern Green Bay, 1973-79.
3. Egg and larvae recovery from egg traps.
I 1st M F1 giirRs
1. The lower Fox River and southern Green Bay.
2. Egg traps.
3. Continuous flow device for rearing experiments.
4. Sampling device for dissolved oxygen and pH.
5. Sampling device for hydrogen sulfide.
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I. Walleye In the Fox River and Green Bay
The wa I I eye (St I zosted 1 on v I treum) I s endem 1 c to Green Bay and the Fox
River (Becker, 1983) and has been a part of the commercial and sport-fishing
catch for many years. In 1885, the annual combined catch of pike and pickerel
(wa I I eye and northern pike) from lower Green Bay was 365,000 pounds (Smith and
Sne I 1, 1 891 ). The wa I I eye, however, has never been an abundant or highly
sought-after component of the fishery in either the Fox River or lower Green
Bay. Past commercial fishing operations in Green Bay have focused on lake
trout (Sa I ve I Inus namaycush)r whltefish (Coregonus cIupeaformis)f lake herring
(Coregonus arted1 I). smelt (Qsmerus mordax), and alewife (AlUia
pseudoharengus). The most abundant catches of walleye have been associated
with sport-fishing activities In northern Green Bay and Big- and Little Bay-
De-Noc in the 1940s (Bertrand ,a_L., 1976). The lower Fox River and
southern Green Bay have, however, received some commercial fishing pressure.
As late as 1973-74, walleye comprised 2.8-3.7$ (by number) of the commercial
catch at a site just downstream of the DePere Dam (Kernen, 1974). Analysis of
data from commercial catch reports and Wisconsin Department of Natural
Resources (WDNR) surveys (Table 1), shows that wa I I eye accounted for 3-15$ of
the catch in the lower Fox River (fyke nets) and <\% of the catch In southern
Green Bay (drop nets). While direct comparison is difficult due to
differences in time and season of sampling and gear selectivity (fyke vs. drop
nets), these data show that wal I eye are a relatively smaI I component of the
overal I catch. The complete species composition breakdown for fyke net
surveys In the Fox River for 1973-79 Is presented in Table 2.
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Table 1. Commercial catch, 1973-1979
a. Lower Fox River - Commercial fyke net (% of total catch)
SpecIes
1973
1974
1975
1976
1977
1978
1979
Wa 1 leye
3
3
8
15
11
6
4
Carp
30
22
19
12
15
26
47
Bu 11 heads
34
34
37
35
51
49
26
Catfish
<1
<1
1
<1
<1
1
4
White Sucker
14
9
8
7
6
3
1
Others
18
31
27
30
16
15
18
b. Southern Green Bay - Commercial drop net (% of total catch)
Species
1973
1974
1975
1976
1977
1978
1979
Wa 11 eye
<1
<1
<1
<1
<1
<1
1
Carp
8
<1
<1
2
<1
3
23
Bu11 heads
51
5
18
13
14
32
6
Catf1sh
<1
<1
<1
<1
<1
<1
1
White Sucker
<1
2
1
<1
<1
2
<1
Others
38
89
78
82
82
61
68
Source: Kernen
(1974)
and Leplnskl
(1978,
1979, and
1980)
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Table 2. Species composition of fyke net surveys (1973-1979)
Bu 11 head
Carp
White bass
White sucker
Black crappie
Alewlfe
Wa11 eye
Gizzard shad
Freshwater drum
Ye I low perch
Shortnose gar
Lake trout
Northern pike
Channel catfish
Burbot
Sauger
Longnose gar
BIueg11 I
Rainbow trout
Rock bass
Shorthead redhorse
PumJ i nseed
Coho salmon
Largemouth bass
White crapp ie
Quill back
Smallmouth bass
Brown trout
Lake sturgeon
Mooneye
Silver redhorse
Green sunfish
American eel
Brook trout
MuskelIunge
Bigmouth buffalo
Longear sunfish
Longnose gar
Flathead catfish
BowfIn
Chinook salmon
Carp (Cyprlnus ^anplQ), bu I I heads (I eta I urns m£j_as, ±. nata I 1 S, and _L.
nebuIosus)f channel catfish (1. punctatus) and white sucker (Catostomus
commerson1) accounted for nearly 10% of the total survey catch over the period
1973-1979 In southern Green Bay and the lower Fox River. Carp, bul I heads and
catfish increased in abundance, especially in the Fox River, over that same
period. Numbers of white suckers, a species usual ly abundant In less perturbed
systems, declined. In 1973 bul I heads were the most abundant species, with carp
placing second; the commercial catch of carp from southern Green Bay and the
lower Fox River that year was 2,000,000 pounds (Kernen, 1975). In 1979, carp
overtook bul I heads as the most abundant fish in the system. These vigorous,
benthic feeding species often disturb bottom sediments and vegetation and may
impact reproduction by other species.
Several factors seem to have Interacted In reducing the viability of the
walleye fishery in the lower Fox River. As early as 1925, the effect of the
DePere Dam in blocking waI I eye migration routes and forcing spawning near the
dam rip-rap was noted (Bertrand £± al., 1976). CI ear Iy, water qua I I ty has
been of potential importance, with municipal and industrial waste discharges
meriting local concern for many years (see below). Final I y, the dominance of
benth ic f i sh spec ies seems i n d irect conf I let w Ith spec ies such as the wa I I eye
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which broadcast spawn and provide no parental care.
Rehabilitation of the walleye fishery has been Identified as a
"[management!] option with high potential" for the lower Fox River and
southern Green Bay (Harr I s £± ,a_L., 1982, p. 32). State-sponsored stocking
programs designed to rehabilitate the Green Bay wal leye fishery began fn 7973.
The Fox River received wal leye flngerl Ings In 1977 and fry in 1978-1982
(Lychwick and Pel I ett, 1982). A tagging operation was Initiated by WDNR In
the fa I I of 1981 and spring of 1982 to assess the size of the walleye
population. Results of the fa I I tagging operation Indicated that 60,000
walleye were occupying the area Immediately below the DePere Dam. Six year
classes were present, primarily representing the five years of fIngerIing/fry
stocking, 1977-1981. The spring, 1982 tagging and netting survey produced an
estimate of 12,000 wal leye In that same area. Recovery by sport fishermen, of
fish tagged In 1981, revealed some Interesting movements by wal leye In the Fox
River system. Wal leye tagged In the lower Fox River were recovered above the
DePere Dam near Little Kaukauna, Little Rapids, Wrlghtstown, Raplde Croche and
Neenah, 6, 6.5, 10, 12, and 32 miles upstream of the DePere Dam, respectively
(Figure 1). A few wal leye moved out of the Fox River and were caught near Egg
Harbor, Sturgeon Bay and the Menominee River (Figure 1) according to Lychwick
and Pel I ett (1982).
Historically, the lower Fox River and southern Green Bay have supported
substantial populations of wal leye. A combination of factors, largely If not
exclusively associated with cultural activities, has seriously reduced the
abundance of wal leye In these regions. Recent stocking efforts by WDNR have
established a resident population of walleye In the lower Fox Riverand
southern Green Bay. Very IIttle movement of the resident population from this
area has been reported, yet natural reproduction In the lower Fox River has
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Figure 1. The lower Fox River and Green Bay
Pound Q
Egg Harbor
7 green
BAY
STATUTE MILES
Green Bay
frown County Fairgrounds
Project Study Site-^J-
Littl# Rapid*
Rapid Croeh*
Lock _
WngMitown
Kaukouno
LAKE \
WINNEBAGO
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not been documented. This study examines several factors which may be
Impacting walleye egg hatching success In the lower Fox River.
11. River Water Quality in Relation ±q His Waileya Fishery
The lower Fox River Is defined here as the 37-mlle segment between Lake
Winnebago and Green Bay (Figure 1). This reach receives Its primary
hydro I ogle loading from Lake Winnebago and Is subject to pollutant discharges
from Lake Winnebago, Industrial and municipal waste treatment plants and
agricultural and urban runoff. Historical ly, water qualIty In the Fox River
has been of major concern to state and local authorities. A 1938-39
Investigation of the lower Fox River concluded that "...these waters could not
support fish I I f e at t Imes of warm temperatures and I ow stream f I ows..." and
that "...the Fox River wll I remain In Its present highly pol luted condition so
long as the sulfite Cpulp] mil Is continue to discharge their waste Into the
stream..." (WSCWP, 1939, p. 14). The passage of more than 40 years has seen a
substantial Improvement In Fox River water quality as a result of the Joint
efforts of government and Industry (cf. Day £± aJ.., 1980). Yet, a recently
published ecosystem rehabilitation plan for Green Bay (Harris et a I., 1982)
Identified the Fox River as the primary source for three of the four critical
stresses Influencing the Green Bay ecosystem (nutrients, suspended solids, and
toxI
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treatment plant effluents (Harr I s £± a±., 1982). Chlorinated hydrocarbons
have been found associated with bottom sediments In tributaries to Green Bay
(Johnson £± a±. 1967) and have bloaccumulated In fish (Hlckey £± .al., 1965)
and herring gulls (Keith, 1966). PoIychI or I nated bI phenyls have been
"Inadvertently discharged" to the Fox River by paper recycling mil Is and are
found associated with bottom sediments and bloaccumulated In fish (Harris et
al., 1982). The impact of toxic substances on the wal I eye fishery In the
lower Fox River are not addressed In this study.
Dissolved oxygen, biochemical oxygen demand (BOD-5) and suspended solids
have been measured in the lower Fox River at the DePere Dam and the river
mouth as part of research on dissolved oxygen in Green Bay (U.S. EPA Grant No.
R809521010). Fox River dissolved oxygen concentrations In late May, 1982
ranged from 8.9-9.7 mg/L. The minimum measured dissolved oxygen
concentrations measured over the period May-October, 1982 were 5.0 mg/L at the
mouth on 19 July and 5.1 mg/L at the DePere Dam on 5 August. BOD-5 ranged from
a I ow of 2.7 mg/L on 25 May 1982 to a maximum of 16 mg/L on 13 July 1982. The
Fox River discharges in nearly 60 metric tons of BOD-5 to Green Bay each day
(annual average, 1978-82). Suspended solids levels In the river range from a
minimum of 7 mg/L on 5 June 1982 to a maximum of 41 mg/L on 10 August 1982.
The average dally discharge (1978-82) of suspended solids to Green Bay from
the Fox River Is In excess of 400 metric tons. The high BOD-5 and suspended
so I I ds I eve I s are ref I ected I n the organ ic, anaerob Ic nature of the bottom
sediments of the river. Bottom sediments In the Fox River and their potential
Impact on oxygen levels are discussed elsewhere In this report.
Much of the Information on hydrogen sulfide, dissolved oxygen and
suspended sol Ids In the lower Fox River Is pub I Ished in the form of reports
which are not a part of the readily available primary literature. This
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Information w TII be summarized In the final report.
III. Importance Selected Environmental Factors iflC Hatching Success
Five factors were Initial ly Identified as being of potential importance
In determining walleye egg hatching success In the lower Fox River:
1) Dissolved oxygen concentration
2) Hydrogen sulfide concentration
3) Sedimentation and substrate character
4) Gamete production and viability
5) Impacts of synthetic organic chemicals
The current study has Investigated the first three factors, dissolved oxygen,
hydrogen sulfide, and sediment/substrate characteristics. Parallel activity
at ERL-DuIuth wI I I address gamete vIabI Iity and the potent I a I Impact of
synthetic organic chemicals.
A. Dissolved Oxygen
Adequate levels of dissolved oxygen have long been recognized as critical
to the maintenance of a healthy and balanced community of aquatic organisms.
Federal and state authorities have established dissolved oxygen standards at
levels designed to protect fish and other aquatic life In streams and rivers.
Flshkll Is linked to dissolved oxygen depletion have been observed In the Fox
River on several occasions (Wisconsin Conservation Commission, 1927 as cited
by Bertrand a_L., 1976). DespIte contemporary improvements In Fox River
water quality (cf. Day £± a_L., 1980), It is reasonable to Identify dissolved
oxygen as a potential barrier to waI I eye egg hatching success In the lower Fox
River.
Two questions need be addressed with respect to dlssolved oxygen and
wa I leye egg hatching success and survival In the Fox River: 1) what are
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the dissolved oxygen levels during the spawning period and 2) what Is the
sensitivity of wa I ley© eggs and larvae to variation In dissolved oxygen
concentration. Walleye In Wisconsin spawn In the spring, shortly after Ice-
out (Becker, T983). Favored spawning temperatures range from 2.2 to 15.5 °C,
with most activity occurring In the range 5.6-7.80C. Eggs usual ly develop
and hatch within 21 days (Prefgel, 1970). Fox River waI I eye spawn during
April and May (Prelgel, 1970 and WDNR, personal communication). Conditions of
high river flow, cold temperature and reduced biological activity during April
and May should lead to neaj—saturation levels of dissolved oxygen In the Fox
River at that time.
Several studies have demonstrated the sensitivity of halleye eggs and
larvae to reduced levels of dissolved oxygen. Slefert and Spoor (1974)
reported that wa I I eye larvae survival at 17 °C was markedly reduced at
dissolved oxygen saturations below 35$ (3.4 mg/L). Over the temperature range
3-8 0 C, greatest eyed-egg and sac-fry mortalities occur at dissolved oxygen
concentrations below 3 mg/L (Colby and Smith, 1967). Little difference In the
development of wal I eye larvae was observed at dissolved oxygen concentrations
of 10, 3, and 2 mg/L for a temperature of 10° C; however, Iarvae held at 1 mg/L
did show poor development (Van Horn and Balch, 1957). Oseld and Smith (1971)
Incubated wal I eye eggs at 1 mg/L Increments from 2-7 mg/L and a temperature of
1 2.1 -13.2 0 C. Egg surv I va I was reduced from 5 8% to 31 % over that range. It
was concluded that low levels of dissolved oxygen substantial ly extended the
time to hatch and reduced the mean length of larvae at hatch. The authors
cone I uded that for opt Imum hatch success, oxygen I eve I s must be ma I nta I ned
above 5-6 mg/L. The results of these studies Indicates that wal leye eggs
exhibit a considerable resistance to reduced levels of dissolved oxygen.
In summary, river water dissolved oxygen levels at preferred spawning
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sites In April and May may be anticipated to be sufficient for the relatively
tolerant waIleye eggs and young. Conditions of dissolved oxygen at the
water/sediment Interface, however, may be quite different. Sediment oxygen
characteristics are discussed below.
B. Hydrogen Sulfide
Hydrogen sulfide Is a natural product of the anaerobic decomposition of
suI fur-containIng organic material. The highly organic benthlc sediments of
the Fox River would be expected to provide a continuous Input of hydrogen
sulfide. Wood fiber sludges associated with the pulp and paper Industry are
particularly we I I known for their capacity to generate hydrogen sulfide.
Hydrogen su I f I de concentrat Ions as h Igh as 260 ug/L were measured I n c I ose
proximity (2 mm) to fiber sludge deposits in the Rainy River of Minnesota
(Colby and Smith, 1967).
Dissolved hydrogen sulfide exists in equilibrium with bisulfide ion and
sul Ifde ion. The relative abundance of the species depends on pH and, to a
lesser extent, temperature. Above pH 9, hydrogen sulfide concentrations are
negl Igable; at pH 8, approximately 10$ of the total sul fide Is present as
hydrogen sulfide, at pH 7.1, 50$ and at pH 6.2, 90$ (Broderlus and Smith,
1976). Sulfide Is highly reactive and may be oxidized to sulfate or may
participate In precipitation reactions with metals such as Iron, lead, and
zinc (Snoeylnk and Jenkins, 1980). Thus, under spring conditions In most
rivers, the presence of substantia I quantities of hydrogen sulfide may be
expected to be highly transient and perhaps IImlted to the sediment-water
Interface.
Fish biologists recognize the toxicity of hydrogen sulfide, especial ly as
a barrier to reproduction. Smith and Oseld (1974, p. 430) state that "many
habitats with unexplained absence of satisfactory fish reproduction should be
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examined for possible natural contamination with hydrogen sulfide In potential
spawning and nursery areas." The authors further state (1974, p. 429) that,
"fish populations which deposit eggs on bottoms where there Is organic
decomposition or where water containing low concentrations of hydrogen sulfide
flows over eggs and fry resting on non-organic bottoms, may have their
reproductive ability limited." Wal leye broadcast their eggs on non-organic
substrate, usually In areas of substantial flow.
Sensitivity to hydrogen sulfide varies with the IIfe history stage of the
f I sh (e.g. egg, fry. Juvenile). Smith and Oseld (1974) reported that the "no
effect" level for hydrogen sulfide Impact on the survival and development of
wal leye eggs and fry was 9 ug/L as HgS. The no effect level for Juvenl le
walleye Is reported as 3 ug/L as h^S (Smith £± Al*» 1976).
Smith and Oseld (1971) observed a 60-80$ survival to hatch In wal leye
eggs exposed to 12-13ug/L HgS; survival was reduced to 13-20$ at 49 ug/L HgS.
Newly hatched fry were thought to be more sensitive to hydrogen sulfide than
eggs of the same species. Shorter length at hatching and embryo deformities
were reported where Incubation occurred In water containing more than 20 ug/L
H2S. Low oxygen concentrations were reported to reduce egg and fry tolerance
to hydrogen sulfide. It Is clear that hydrogen sulfide Is a potential barrier
to wal leye reproduction In the Fox River. The critical task Is to obtain the
necessary spatial resolution In sampling and analysis to detect the presence
of H2S at the sediment/water Interface.
C. Seri1mentation Substrate Character
Wal leye broadcast their eggs over large expanses of coarse gravel, rock
or sand In moving water and clear shoreline areas (Auer, 1982). Although the
Fox River contains large regions of highly organic sediment, there are areas
of clean substrate with substantial flow. Wal leye have been observed to
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congregate near the rip-rap at the base of the DePere Dam during spawning
season and are believed to spawn In that area (WDNR, personal communication).
Wa I I eye eggs deposited In regions of high flow are not IIkely to be
Influenced by sediment or the products of sediment dIagenesis. If Fox River
wal I eye are forced to use less desirable substrate due to dam placement and/or
water level regulation, sedimentation and chemical effects may Influence egg
survival.
IV. Matariais Methods
A. Fish and Egg Hand Ilng
Suitable spawning substrate In the lower Fox River Is limited (WDNR,
personal communication). Sexual ly ripe wal I eye are Known to congregate each
spring at a site approximately 1 km downstream of the DePere Dam. The bottom
sediment In this area Is primarily sand and water flows with sufficient
velocity to keep the substrate free from debris. Each spring, Wisconsin DNR
personnel col lect ripe and spent adult wal I eye from the lower Fox River and
record length, weight and sex Information; these fish are then tagged and
released. Adult walleye used In this study were provided by WDNR personnel
during tagging operations on 21 April 1983, the peak of the spawning period.
Water temperature at the time of capture was 7° C (44° F).
Several ripe male and female wal I eye were taken from WDNR nets and
transported In portable metal mesh fish baskets to the study site staging
area at the Brown County Fairground. Eggs from two large femaJes were
immediately stripped Into a clean, dry plastic tub and milt from five males
was squeezed directly onto the eggs. The mixture was slowly stirred with the
fingers. After thorough mixing of the gametes, river water was slowly added
to the tub. Eggs were repeatedly rinsed untl I the rinse water remained clear.
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Eggs were not "mudded" to prevent adhesion, as the volume of eggs was smal I
and would be placed Immediately Into egg-hatching traps. Very little clumping
of eggs was observed.
AlI traps received fertlIIzed eggs from the single batch harvested on 21
April 1983 (the start of ontogeny or Day 1). Fol lowing thorough mixing, three
units of fertilized eggs were Inoculated Into each of eight test traps using a
calibrated buIb/plpette. Four units of eggs were used for control traps. In
each case, equivalent volumes were preserved In 10$ formaldehyde for later
enumeration.
Subsamples of the batch of fertilized eggs were examined Immediately to
determine the percentage of live eggs In each trap. It Is difficult to
differentiate fertilized live eggs from unfertilized live eggs at this stage
of development. For the purposes of this study It Is assumed that all I Ive
eggs were fertl I e. Eggs remaIn Ing after samp I i ng and trap-fII I I ng were
transported to Michigan Technological University for laboratory rearing
experiments.
B. Trap Construction .and Placement
Ten egg-hatching traps were constructed speclflcal ly for wa I leye eggs
using a modification of the design by Swanson (1982). Traps were constructed
of corrosion-resistant aluminum and measured 96.5 cm In length by 8.9 cm wide
i
by 57.2 cm high. The narrow design was Intended to minimize sediment and
debrIs accumuI at Ion and to maxim Ize f I oatatIon capabII It Ies. A bIock of
styrofoam, 91 cm long, 7.6 cm wide and 20.3 cm high was fitted to the top of
the trap, out of contact with the egg chamber. The egg compartment section of
the trap was 91.4 cm In I ength by 7.6 cm wIde by 20.3 cm h Igh. The open faces
of the egg compartment were covered with 0.75 mm [1 mm diagonal opening^ mesh
net (Tetko inc., PeCap ASTM 7-25-7J0). Wal leye eggs range from 1.5-2.1 mm In
1 6
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diameter; the depth at yolk sac of recently hatched larvae ranges from 1.18-
1.42 mm (Auer, 1962). Photographs of the traps are provided as Figure 2.
Two types of egg traps-were used: gravel traps and turf traps. A two-
Inch layer of washed pea gravel was placed In each of six "gravel" traps.
FertIIIzed eggs were expressed Into the trap through a delIvery port. The egg
compartment of the remaining four traps was outfitted with a six-layer turf
"sandwich11 composed of two layers of plastic grass with two layers of
artificial turf on each side. The turf sandwich had a length of 91.4 cm and a
height of 22.9 cm, leaving an open space, 7.6 cm high In the egg compartment.
Eggs were expressed onto the grass surface, the layers of plastic grass and
artificial turf sandwiched together, and the trap sealed.
FN I ed traps were p I aced at se I ected sites by d I vers and anchored I n
place, para I lei to the current, with cast Iron weights. Eight of the ten
traps (four gravel, four turf) were placed on sandy substrate at a site on the
east bank of the Fox River approximately 1 km downstream of the DePere Dam
(Figure 1). The control traps (both gravel) were placed at a site 5 km
upstream from the mouth of the Oconto River and in an outdoor raceway at the
Evergreen trout hatchery In Pound, Wisconsin.
Paired traps (one gravel, one turf) were harvested from the Fox River
site on Days 7, 13, and 19 (2 sets). Traps were moved submerged and Intact
from the incubation site to the dock at the Brown County Fairground. The traps
were opened and the contents washed Into a 363 micron, #2 mesh nylon plankton
net. The gravel and turf were gently mixed with water several times to al low
larvae and eggs to float free, uninjured. AI I eggs, larvae and debris washed
from the traps were held at river water temperature and aerated until ready
for laboratory examination (general ly within two hours). Control traps were
harvested using this method on Day 18.
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Figure 2a. Egg traps - Front view, assembled
crzcr
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PljCMI^ TCCU UMTV
~ftzc H Tfcc
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C. Rearing Experiments
Eggs remaining after fl I IIng traps were aerated and transported on Ice to
the laboratory at Michigan Technological University. The eggs were then
placed In a mixed, aerated, continuous flow device (Figure 3) f I I led with Fox
River water. A supply of refrigerated Fox River water was slowly dripped Into
the device via a poly-stalttc pump; overflow water was discharged to waste.
o
The device was maintained In the dark at 10 C In a Perclval Incubator (Boone,
I A). Eggs were exam I ned da 11 y and a I I eggs w I th f unga I contam I nation were
removed. Developmental stages were Identified using physical characteristics
described by 01 sen (1966). Photographs of eggs and larvae were made using a
35 mm Nlkkormat camera and either a microscope or dissecting scope.
D. Fungi
Samples of Fox River water and wal leye eggs were transported In sterile
containers, on Ice, to the laboratory at Michigan Technological University.
Eggs (surface sterilized) and river water were plated on Rose Bengal agar and
Incubated at 20°C for 7 days. A water sample from Portage Lake, Houghton
County, Michigan was plated as a control. Fungi developing on the agar were
quantified and Identified.
E. Larval Fish Samp IIng
4
Samp I Ing for natural ly-spawned larval wal leye was conducted at three-day
Intervals over the period 25 April to 6 June 1983. Sampling was conducted at
night, In the Fox River near the egg trap study site. Fish, larvae,
arbltrarl ly defined as <1 Inch In length, were col I ected by towing a 0.5 m
diameter nylon plankton net (#2 mesh, 363 micron aperature) behind a boat for
5 minute periods. The volume of water filtered was quantified using a 5 Inch
diameter marine flowmeter (6.M. Mfg. 4 Inst. Co., Bronx, N.Y. 10451) with
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Figure 3. Continuous flow device for rearing experiments.
Air exhaust
and
overflow
Syringe
sample
port
cf)33
Pyrex
paddles
with
teflon
ends
Medium
inlet port
Air inlet
Magnetic
stir bar
21
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dial counter attached to the center opening of the net. Fish larvae were also
col I ected by seining the east and west shores at the study site. The seine
has two 48 Inch wings of #00 mesh and a center, 40 square Inch #2 mesh cod
end. Samples were preserved with formaldehyde for later Identification and
enumeration. This component of the project Is not complete; the target date
for a preliminary report Is 16 December 1983.
F. Sediment Survey
During the spring and summer of 1983, sediment grab samples were
col lected on at five locations on each of 68 transects between the Fox River
mouth and the dam at DePere. Sediment samples were analyzed for COD, volatl le
solids, moisture content, and gross texture. A relationship between sediment
COD and sediment oxygen demand developed for the Green Bay oxygen project will
be used to characterize the oxygen demand of Fox River sediments. The
distribution of suitable spawning substrate can also be Identified from this
survey. This component of the project Is not complete; the target date for a
preliminary report Is 16 December 1983.
G. Chemical Analyses
Water samples for determination of dissolved oxygen, hydrogen sulfide and
pH were col lected on 21 Apr I I 1983 (as traps were set) and 9 May 1983 (as
final traps were harvested). Water samples for dissolved oxygen and pH were
col lected at the surface and at 14 Intervals In the 100 cm above bottom using
the siphon apparatus Illustrated In Figure 4. Dissolved oxygen was measured
using the azlde mod I f I cat I on of the W I nk I et techn Iq ue (APHA, 1980). pH was
measured using an Orion electrode and Corning Model 12 meter.
Water samples for hydrogen sulfide analysis using the multiple-syringe
apparatus pictured In Figure 5. The syringes were filled by divers, capped,
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Figure 4. Sampling device for dissolved oxygen and pH.
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and the entire apparatus brought to the surface. The water was then forced
from the syringe, through a 0.45 micron filter Into 50 ml media bottles
containing 2 mis of 0.1 molar zinc acetate. Preserved samples were stored at
room temperature. Total dissolved sulfide was measured using the methods of
APHA (1980) and Smith £± al. (1976); hydrogen suIfIde concentratIons were
determined using temperature/pH/Ionization constant relationships.
Figure 5. Sampling device for hydrogen sulfide.
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V. Results .and Discussion
A. Iflfi Traps
The number of wa I I eye eggs placed In each trap was estimated from the
Inoculation volume and the measured density of eggs In the fertilizing vessel.
Traps placed In the Fox River contained approximately 4600 eggs, 2600 of which
(56$) were alive and assumed fertilized. Control traps contained a total of
2760 eggs, 1550 of which were viable.
The first pair of traps (one gravel, one turf) was harvested from the Fox
o
River after 7 days of Incubation. Water temperature on that date was 13 C.
Of 3407 eggs recovered from the gravel trap, 3177 (93$) were considered non-
viable (opaque, white, and/or fungus-Infested) and 230 (7%) were alive. The
vertebral column and outlines of the eyes of the larvae were clearly visible
through the cor Ion cf I Ive eggs recovered on Day 7. Of 2387 eggs recovered
from the turf trap, 2219 (93$) were dead and 168 (7$) were v lab I e and showed
normal signs of development.
The second pair of traps was harvested after 13 days of Incubation.
Water temperature on that date was 10.5 °C. Of 2367 eggs recovered from the
gravel trap, 24 (1$) were alive. One hatched larva was found swimming In the
trap. Many of the dead eggs were clumped and heavl ly Infested with fungi;
over 200 chlronomid larvae were found associated with the egg clumps. Only
three (<1$) viable eggs were observed among 698 eggs recovered from the turf
trap. Fewer chlronomlds (75) and less fungal contamination were observed for
the turf trap.
The final two pair of traps were harvested from the Fox River after 19
days Incubation. Water temperature at that time was 11.5° C. No I Ive eggs
were observed among 607 and 1793 eggs recovered from the two gravel traps; one
live larva was found. The dead eggs were heavily Infested with fungus;
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chlronomld larvae, too numerous to count, were observed among the egg clumps.
The turf traps had col lected large quantities of slit and organic debris. No
live eggs or larvae were observed among the 753 and 900 eggs recovered from
the turf traps.
The control traps were harvested after 18 days Incubation. The (gravel)
trap placed at the fish hatchery contained one live egg among 1966 eggs
recovered. No funal growth was observed, but large amounts of organic
mater la I, resemb i f ng fish food pel let deb r! s, was found I n the trap and may
have Influenced egg development. The (gravel) trap from the Oconto River
contained 597 dead eggs and 18 hatched, live larval walleye. The results of
egg recovery are summarized in Table 3.
B. Rearing Experiments
Eggs incubated in the laboratory at Michigan Technological University
were used to estimate development and time to hatch for fleid-Incubated eggs.
Laboratory egg development proceeded through the hatching stage, but no
hatched larvae survived. Eggs were incubated In Fox River water which
supported a prolific population of fungi. Many developmental stages of eggs
and larvae were photographed.
C. Fungi
plates of Fox River water and wal leye eggs supported 110 fungal colonies
per ml of river water, while the Portage Lake water control plates supported
20 fungal colonies per ml of lake water. Two varieties of fungi were observed
on the Portage Lake control plates, while 3-4 varieties were observed on the
Fox River water plates. One variety was much more abundant than a I I others and
was thought to be Saprolegnla. the species found growing from the surface of
sterilized eggs. Researchers from Wisconsin DNR have attempted to raise lake
26
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herring (Coregonus artedl1) by Incubating eggs In Green Bay water. The eggs
reportedly grew wel I until the eyed stage, at which point heavy fungal growth
developed and all eggs were lost (B. B longer, WDNR, personal communication).
Table 3. Egg and larvae recovery from egg traps,
a. Fox River - Gravel Traps
Day Eggs % Eggs Viable Larvae
1 4600 56 na
7 3407 7 0
13 2367 1 1
19 1793 0 1
19 607 0 0
b. Fox River - Turf Traps
Day Eggs % Eggs Viable Larvae
1 4600 56 na
7 2387 7 0
13 698 <1 0
19 753 0 0
19 900 0 0
c. Hatchery Control - Gravel Trap
Day Eggs % Eggs Viable Larvae
1 2760 56 na
18 1966 <1 0
d. Oconto River Control - Gravel Trap
Day E99S % Eggs Viable Larvae
1 2760 56 na
18 597 0 18
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D. Chemical Analyses
Water samples were col lected on the first day of egg Incubation (21 April
1983) and the final day of trap harvest (9 May 1983) at 5 or 10 cm Intervals
beginning at 5 cm above the bottom. Only si Ight variation In dissolved oxygen
concentration was observed within that distance. Dissolved oxygen
concentration ranged from 13.1-13.7 mg/L (124-129 % saturation) on 21 Aprl I
and from 10.2-11.5 mg/L (96-105 % saturation) on 9 May.
Total dissolved sulfide levels ranged from negllgable to 1.2 ugS/L on 21
April and from 0.6 to 4.1 ugS/L on 9 May. Actual values for each depth are
presented in Table 5. Over the range of pH (8.05-9.15) and temperatures
(11.5-13° C) at the Fox River study site, 10? or less of the total sulfide Is
present as the toxic form, hydrogen sulfide. Thus, the hydrogen sulfide
content of Fox River water samples at all depths on both dates was <1 ug/L.
VI. Summary .and Conclusions
A.Trap Construction
Trap construction and Incubation procedures were satisfactory for the
retention and culture of eggs and larvae. Low recovery/surv IvaI numbers In
turf traps compared with gravel may have been due to poor circulation of
oxygen and fresh water In turf traps. Both approaches afforded some
protection from sedimentation and predatlon, however, trap Invasion by
chlronomld larvae and abundant fungal growth were not avoided.
B. Gamete Viability
The combined gametes from adult Fox River ual I eye proved viable In both
field and laboratory studies; however, survival beyond hatch was not observed
In either case. Gamete viability Is only one of several factors fundamental
28
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+o the es+ablIshment of a natural ly reproducing wal I eye population.
C. Fungal Growth and Chlronanld Larvae
Fungal growth and predatlon by chlronanld larvae must be acknowledged as
potential barriers to egg development. As eggs died and developed profuse
fungal growth, chlronomld larvae may have been attracted to available sources
of she I ter and food. Sapro I egn 1 a usua I I y grows from dead eggs, but w I I I
spread to live eggs. This fungal species was 5.5 times more abundant In Fox
River water than In the Portage Lake (Houghton Co., Ml) control water. It Is
suggested that Fox River water, rich In organic material, may support an
unusual ly high standing crop of fungi.
0. Sediment and Benthfc Ffsh Species
Sediment deposition and resuspenslon by benthlc fish may play an
Important role In wal I eye egg hatching success. Wal I eye eggs may be smothered
by sol Ids settling from the water column In quiescent areas. Carp, buI I heads,
and catfish, a I I abundant In the lower Fox River, can resuspend sediment and
consume eggs as part of their vigorous, benthlc feeding activities. Bui I heads
and carp exhibit parental care or such great fecundity that their survival Is
assured, even under suboptlmal condltons.
E. Hater Quality
Water quality conditions, as evidenced by dissolved oxygen or hydrogen
sulfide levels, do not appear to be significant barriers to wal (eye egg
hatching success. Dissolved oxygen levels In the water column are near
saturation during the spawning period. Hydrogen sulfide levels were <1 ug/L
at al I depths. The fact that no sampling was conducted at the sediment/water
Interface must not, however, be overlooked.
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F. Future Directions
The following questions should be addressed to further clarify the
potential for rehabilitation of the lower Fox River walleye fishery:
1. What are the dissolved oxygen and hydrogen sulfide concentrations
at the sediment/water Interface? This can be measured In cores or
directly at the study site.
2. Are eggs burled by sediment? Smothering can be examined in the
river In open-topped traps.
3. Do adult vail eye complete the spawning act and produce fertilized
eggs? Samp I Ing for the presence of wat I eye eggs In the river could
address this point.
4.Ifhat Is the survival rate for post-hatch young? This would be
addressed under control led laboratory conditions.
5. What role do heavy metals and synthetic organic chemicals play?
This may be an appropriate direction for activities at ERL-Duluth.
VI J. Acknowledgements
We would I ike to thank Doug Welch, Terry Lychwlck, and Jim Moore of WDNR
for providing assistance In locating study sites, collectlng adult wal I eye,
and obtaining reports on the Green Bay/ Fox River fishery. Fred P. Sinkowski
of the Center for Great Lakes Studies, University of Wisconsin-Milwaukee
assisted in trap design. K.E.F. Hokanson, of U.S. EPA ERL-Duluth Is
provided constructive criticism and many valuable reprints.
Dr. Susan T. Bag ley and Dr. Johann Bruhn of Michigan Technological
University carried out the identification and quantification of fungi. Dr.
Bag ley and Mr. David Perram are acknowledged for their efforts In developing
the technique for sulfide analysis. AI I sediment analyses were performed by
Mr. Robert D. Gardiner. The contributions of Mr. Richard Lamparter and Mr.
Phil Dennis of the BloSource Institute at Michigan Technological University,
as we I I as the crew of the R/V SISU are greatfu I ly acknowledged.
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Vlll. Literature cited
American Public Health Association. 1980. Standard Methods for the
Examination of Water and Wastewater, ed. 14. Amer. Public Health
Assoc., Water Pol I. Control Fed., and Amer. Water Works Assoc.,
Washington, D.C. 1193 pp.
Auer, N.A. 1982. Family Percldae, perches, pp. 581-648. ±d: N.A. Auer
(ed.) Identification of larval fishes of the Great Lakes basin with
emphasis on the Lake Michigan drainage. Great Lakes Fishery
Commission, Ann Arbor. Spec. Pub I. 82-3, 744 pp.
Becker, G.C. 1983. Fishes of Wisconsin. The Univ. of Wisconsin Press,
Madison. 1052 pp.
Bertrand, G., J. Land and J. Ross. 1976. The Green Bay Watershed:
Past/Present/Future. Unfv. of Wis. Sea Grant College Program, Tech.
Rept. #229. 300 pp.
Broderius, S.J. and L.L. Smith, Jr. 1976. Effect of hydrogen sulfide on
fish and Invertebrates. Part II. - Hydrogen sulfide determination and
relationship between pH and suIfIde toxic 1ty. U.S. Environmental
Protection Agency. ERL-Duluth, MN. EPA-600/3-76-0626. 109 pp.
Colby, P.J. and L.L. Smith, Jr. 1967. Survival of walleye eggs and fry
on paper fiber sludge deposits In Ratny River, Minnesota. Trans.
Amer. Fish. Soc. 96(35:278-296.
Day, H.J., M. Asce, W. Elman, D. Theller and R. Chr I st lanson. 1980.
River clean-up plan developed with citizens and Industry. Civil
Engineer Ing-ASCE, March, pp. 78-81.
Harris, H.J., D.R. Talhelm, J.J. Magnuson, and A.M. Forbes. 1982. Green
Bay In the future - A rehabilitative prospectus. Great Lakes Fishery
Commission, Tech. Rept. No. 38. 59 pp.
Hickey, J.J., J.A. Keith and F.B. Coon. 1966. An exploration of
pesticides In a Lake Michigan ecosystem. Journal of Applied Ecology.
Vol. 3. (supplement).
tJohnson, W.O., F.D. Fuller and L.E. Scarce. 1967. Pesticides In the
Green Bay area. Proc. 10th Conf. Great Lakes research. International
Assoc. Great Lakes Res., pp. 363-374.
Keith, J.A. 1966. Reproduction In a population of herring gulls (Larus
argentatus) contaminated by DDT. Journal of Applied Ecology. Vol. 3
(supplement): 57-70.
Kernen, L.T. 1974. Fishery Investigations on the lower Fox River and
South Green Bay In 1973-1974. WDNR unpublished. 10 pp.
Kernan, L.T. 1975. Carp tagging study. WDNR unpublished. 11 pp.
Leplnskf, P. J978. 1977 Monitoring of commercial fishing operations -
Fox River. WDNR unpublished. 5 pp.
31
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Leplnskl, P. 1979. 1978 Fox River fish population Investigations. WDNR
unpublished. 8 pp.
Leplnskl, P. 1980. 1979 Fox River and Green Bay fish population
Investigations. WDNR unpublished. 10 pp.
Lychwlck, T.J. and T.D. Pellett. 1982. Walleye assessment. Lake
Michigan (Green Bay). WDNR unpublished. 47 pp.
Olson, D.E. 1966. Physical charaterIstIcs of fertilized and
unfertilized walleye eggs during early stages of development. Minn.
Dept. Conserv., Minn. Fish. Invest., 4: 31-38.
Oseld, D.M. and L.L. Smith, Jr. 1971. Survival and hatching of wal leye
eggs at various dissolved oxygen levels. Prog. Fish-Cult., 33(2): 81-
85.
Prlegel, G.R. 1970. Reproduction and early life history of the walleye
in the Lake Winnebago region. Wis. Dept. Nat. Res., Tech. Bull. 45.,
105pp.
Slefert, R.E. and W.A. Spoor. 1974. Effects of reduced oxygen on
embryos and larvae of the white sucker, coho salmon, brook trout, and
walleye. pp. 487-495 In: J.H.S. Blaxter (ed.). The Early Life
History of Ffsh. SprInger-Verlag, N.Y. 765 pp.
Smith, H.M. and M.-M. Snell. 1891. I. Review of the fisheries of the
Great Lakes In 1885, compiled by H.M. Smtth and M.-M. Snell with
introduction and descriptions of fishing vessels and boats by J. W.
Collins. Report of the Commission for 1887, U.S. Commission on Fish
and Fisheries 1891. p. 84.
Smith, L.L., Jr. and D.M. Oseld. 1971. Toxic effects of hydrogen
sulfide to juvenile fish and fish eggs. Proc. 25th Purdue Indust.
Waste Conf., Eng. Ext. Serv. Bull. No. 137, pp. 739-744.
Smith, L.L., Jr. and D.M. Oseld. 1974. Effect of hydrogen sulfide on
development and survival of eight freshwaer fish species, pp. 417-430
1 n: J.H.S. Blaxter (ed.) The Early Life History of Fish. Sprlnger-
Verlag, N.Y.
Smith, L.L. Jr., D.M. Oseld, I.R. Adelman and S.J. Broderlus. 1976.
Effect of hydrogen sulfide on fish & Invertebrates. Part 1 - Acute
and chronic toxicity studies. U.S. Environmental Protection Agency.
ERL-Duluth, MN. EPA-600/3-76-062a. 286 pp.
Snoeylnk, V.L. and D. Jenkins. 1980. Water Chemistry. John Wiley &
Sons, New York. 463 pp.
Swanson, B.L. 1982. Artificial turf as a substrate for Incubating lake
trout eggs on reefs In Lake Superior. Prog. Fish-Cult., 44(2>: 109—
111.
Van Horn, W.M. and R. Balch. 1957. The reaction of wal leyed pike eggs
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to reduced dissolved oxygen concentrations. Purdue Univ. Eng. Ext.
Dept. Series 91: 319-341.
Wisconsin State Committee on Water Pollution. 1939. Investigation of
the pollution of the Fox and East Rivers and of Green Bay In the
vicinity of the city of Green Bay. Madison, Wisconsin. 242 pp.
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