Life History, Ecology and Habits of the Dwarf Sucker,
CATOSTOMUS COMMERSONNII UTAWANA Mather,
at the Huntington Wildlife Station

By

W. A. DENCE

ROOSEVELT WILDLIFE BULLETIN
Volume 8 JUNE, 1948 Number 4

Roosevelt Wildlife Forest Experiment Station

New York State College of Forestry
at Syracuse University, Syracuse, N. Y.

Joseph S. Illick, Dean

Life History, Ecology and Habits of the Dwarf Sucker,
CATOSTOMUS COAIMERSONNII UTAWANA Mather,
at the Huntington Wildlife Station

By

W. A. DENCE

ROOSEVELT WILDLIFE BULLETIN
Volume 8 JUNE, 1948 Number 4

VOLUME XXI NUMBER 3

Published quarterly by the New York State College of Forestry at Syracuse, N. Y.
Entered as second-class matter, October 18, 1927, at the Post Office at
Syracuse, N. Y., under Act of August 24, 1912.

ANNOUNCEMENT

The serial publications of the Roosevelt Wildlife Forest Experi-
ment Station consist of the following:

1. Roosevelt Wildlife Bulletin

2. Service Publication

The Bulletin includes papers of a technical or semi-technical nature
dealing with various phases of forest wildlife, its management and
conservation. The Service Publication is intended to be of general and
popular interest and attempts to interpret forest wildlife research
results and explain the reasons for and methods of their application.

The editions of the Bulletin are limited and do not permit of general
free distribution. Prices of the individual numbers vary as they are
based on actual cost of printing and distribution in accordance with
Chapter 220 of the Laws of 1933. Price lists will be furnished on
request. Exchanges are invited. All communications concerning
publications should be addressed to :

THE DIRECTOR
Roosevelt Wildlife Forest Experiment Station
Syracuse, New York

Notice: This issue is the fourth number of a new series of the Bulletin.
Each issue liereafter will contain only one article and the number of
issues per volume will be determined by the size of the individual
numbers.

TRUSTEES OF THE NEW YORK STATE
COLLEGE OF FORESTRY

EX OFFICIO

Joe R. Hanley, Lieutenant-Governor Albany, N. Y.

William P. Tolley, Chancellor, Syracuse Universily . Syracuse, N. Y.

Francis T. Spaulding, Commissioner of Education... Albany, N. Y.

Perry B. Duryea, Conservation Commissioner Albany, N. Y.

APPOINTED BY THE GOVERNOR

J. Henry W alters, President New York, N. Y.

Francis D. McCurn, Vite-Fresident Syraci-se, N. Y.

W illis H. Michell Syracuse, N. Y.

Charles D. Upson Lockport, N. Y.

George R. Fearon Syracuse, N. Y.

George W'. Sisson, Jr Potsdam, N. Y.

Grant W. Ernst Syracuse, N. Y.

Orville H. Greene Syracuse, N. Y.

Frank C. Ash Fulton, N. Y.

STAFF OF THE ROOSEVELT WILDLIFE FOREST
EXPERIMENT STATION

Joseph S. Illick, D. Sc Dean of the College

Hardy L. Shirley, Ph.D Assistant Dean of the College

Ralph T. King, M.A Director

Wilford a. Dence, B.S Ichthyologist and Assistant Professor

William L. Webb, M.S Assistant Professor

Marianna Neighbour Secretary

[81 ]

Fig. 15. A typical pair of dwarf suckers — the upper hsli a five-inch male, the
lower fish a five and three-fourths-inch female.

Fig. 16. A common sucker and a dwarf sucker taken on same da\ at Wolf
Lake.

[82]

Life History, Ecology and Habits of the Dwarf Sucker,
CATOSTOMUS COMMERSONNII UTAWANA Mather,
at the Huntington Wildlife Station

By

W. A. DENCE
CONTENTS

PAGE

Introduction 84

History 84

Purpose 87

The Wolf Lake habitats 87

Acknowledgments 89

Field methods and techniques 89

Collecting in the inlets 90

Marking 90

Collecting in Wolf Lake 91

Descriptions 94

Mather's description 94

Huntington Forest dwarf suckers 95

Color 96

Unusual color phase 97

Size 98

Pearl organs or tubercles 100

Scales 102

Fins llJ3

Common suckers and dwarf suckers in the same habitat 105

Spawning migration 106

Spawning habitat 112

Special reactions 116

Reaction to inlet waters 116

Reaction to loss of fins 116

Limnological relations 118

Temperature 118

Dissolved gases 118

Macroscopic bottom organisms 119

Other features 120

Correlation of temperature and spawning activities 120

Sex ratios 123

Returns from marked fish 127

Fecundity and early life development 134

tgg productivity 134

Incubation . . .' 134

Development of fry 135

Food and food relations 136

Age determinations 137

Economic and social relations 142

Parasites 147

Literature cited 149

[83]

84

Roosevelt Wildlife Bulletin

INTRODUCTION

History. Dwarf suckers, Catostomus commersonnii utawana
Mather, (Fig.15) appear to be limited in distribution to certain lakes
of the Adirondacks in New York State. They were first described by
Mather (1890) who discovered them on June 23, 1890 in a small pond
in the Blue Mountain Lake region, less than twenty-five miles south-
west from the site of the present study. A few days later he found
the species* in the Big Moose Lake region. Even with such meagre
knowledge of freshwater fishes available at that time, Mather recog-
nized that the fish in question, while quite similar in many respects to
the common sucker, Catostomus commersonnii commersonnii (Lace-
pede), obviously was different, particularly as regards its smaller size
at maturity (Fig. 16) and its later spawning season. Mather's speci-
fic name "utawana" is that of a small lake in the Blue ^lountain
Lake drainage and was chosen purely for sentimental reasons.

Kendall and Dence ('29) found what obviously was the same
species of sucker during the course of their studies on the fishes of the
Cranberry Lake region. These writers recognized that Mather was
justified in assuming that he had discovered a fish new to Science.
They were quite surprised, however, to learn that it had not been in-
cluded on more recent lists of Adirondack fishes.

Taxonomically the dwarf sucker is so similar to the common
sucker that there is insufficient justification for classifying it as a
distinct species as did blather. It is, therefore, being generally recog-
nized and classified as a subspecies of Catostomus commersonnii with
Mather's specific title "utawana" being relegated to the subspecific
position. (Greeley and Greene, '31.)

The Biological Survey party of the New York State Conserva-
tion Department found dwarf suckers in the Oswegatchie and Black
River systems (Greeley and Greene, '31), in the L'pper Hudson
watershed (Greeley and Bishop, '32), and in the Raquette River
watershed (Greeley, '34). The two subspecies of Catostomus com-
mersonnii frequently occur in the same body of water. Greeley (I.e.)
found this to be the case at Lake Eaton, while the writer encountered
both subspecies at Wolf Lake and elsewhere during the course of
this study.

Although the dwarf sucker is believed to be quite generally
distributed throughout the Adirondacks, it appears to be limited to
tlie deeper lakes where the summer temperatures do not become
excessively high. The writer has never found them where the maxi-

* Catostomus utawana according to Mather.

Fig. 17. Lengthwise view of Wolf Lake from point near South Inlet.

Fig. 19. Collecting pool for dwarf suckers, in North Inlet of \\olf Pond.
Several hundred suckers congregate in this pool throughout the spawning
season.

Fig. 20. Spawning area of dwarf suckers in Xorth Inlet of Wolf Pond.
The fish were unable to get beyond the barrier of logs, sticks, etc., shown
in the background until freshets removed the debris early in 1944.

[86]

Life History, Ecologx and Habits of the Dimrf Sucker 87

mum summer temperature in the lake Iiabitat greatly exceeded that
which native brook trout can endure.

At Wolf Lake, on the Huntington Forest, near Newcomb, New
York, where the data for this report were obtained, dwarf suckers
and brook trout invariably frequented the same habitats, and con-
sequently were usually captured simultaneously in the nets. In
fact the task of collecting dwarf suckers without afifecting the trout
population seemed to be impossible, and resulted in the suspension
of netting operations sooner than was originally planned. The trout
died very soon after becoming enmeshed in the nets, but the suckers
suffered no ill effects unless badly tangled in the meshes.

The meagre knowledge of the dwarf sucker is due in part to its
secluded existence because, with the exception of about ten days or
two weeks annually during the spawning season, it inhabits deep
water. Some individuals in every lake and the entire population of
other lakes appear to spend their whole existence in the lake proper,
in lieu of adequate spawning facilities in the streams.

Purpose. The study was inaugurated for the following rea-
sons : ( 1 ) Preliminary investigations shortly after the property
was acquired revealed that the tributary streams of Wolf Lake
offered an unusual opportunity to acquire detailed knowledge on a
fish subspecies which previously had scarcely been known to Scien-
tists; (2) To study the relations between this and the common
sucker; (3) It was part of the general program of research and
investigation outlined for the Huntington Wildlife Forest (King,
Dence and Webb '41, p. 411).

The Wolf Lake Habitats. Most of the data for this report
were obtained from Wolf Lake (Figs. 17 and 18) and its inlets
because ; ( 1 ) there was a great abundance of dwarf suckers in this
lake; (2) the physical condition of the inlets with respect to depth,
width, and obstructions, such as boulders, logs and stumps, was
quite ideal for seining fish; (3) there were two inlets, one at each
end, that were being used by spawning fash — an especially desirable
feature in connection with migration activities; (4) Wolf Lake was
not affected in any manner by exotic species; and (5) the possibility
of minimum disturbance from the general public and from other
activities on the Forest.

Dwarf suckers were more abundant at Wolf Lake than thcv
were at any of the other lakes on the Forest. In fact there was a
greater concentration of suckers here than previously had been en-
countered by the writer elsewhere in the Adirondacks. Some idea
of their abundance may be obtained from the statement that during

88

Roosevelt Wildlife Bulletin

the peak of the spawning season on several occasions more than 400
specimens, were landed in a single short haul with the six-foot seine,
and hauls of a hundred or more were very common. The large
hauls were from what may be called resting pools or retreats —
places where the suckers congregated while enroute to or from the
spawning beds or where they retreated when disturbed. The data
on dwarf suckers at Wolf Lake were supplemented and checked
with those from other lakes on the Forest and from adjacent areas.

The inlet at the north end of Wolf Lake (hereinafter called
North Inlet) is tl^e larger and most important of the two principal
inlets. The upper part of North Inlet was rather precipitous and
characterized b}' many boulders. It, invariably, became dry during
periods of scant rainfall. The lower 3^ mile meandered through
rather flat, partially wooded country, part of which was inundated
several years ago as the result of a beaver dam in the adjacent out-
let. The stream did not exceed eight feet in width during normal
water levels, and usually averaged about six feet. The depth of
water on the riffles usually varied from a few inches to about a foot
during the sucker spawning season — that in the pools from one to
two feet. The bottom consisted of small rocks and boulders with
considerable coarse sand and gravel. The pools and certain stretches
were characterized b}' coarse sand and gravel. This lower section
becomes extremely low in volume of water during droughts but
seldom completely dries.

The inlet at the south end of the lake (hereinafter called South
Inlet) originates in a small bog less than one-half mile from the
lake. It flows through a low ravine and except for a few rods near
the lake has a mucky bottom. The part nearest the lake meanders
through a former beaver meadow, and this portion was used by the
spawning dwarf suckers. It was about three feet wide in this sec-
tion, and about a foot deep during the spawning season. The cover
for this section consisted of speckled alder and pole-size hardwoods.
The bottom was mostly of fine and coarse sand with a few small
boulders and cobblestones in certain spots. Both streams formed a
delta of fine sand upon entering the lake.

Wolf Lake is approximately one mile long and one-fourth mile
wide, with its long axis extending in about a north-south direction.
It has a total area of 143.74 acres, of which 108.4 acres are ten feet
or more in depth. There are two depressions in the lake — one in
about the mid-region of the southern portion, with a maximum
depth of 45 feet and the other slightly south of the mid-region of
the northern portion with a maximum deptli of 40 feet. The ridge

Life History, Ecology and Habits oj the Divarf Sucker 89

between these depressions normally is about 20 feet below the sur-
face of the water.

The bottom on approximately three-fourths of the lake (that
beyond the littoral zone) consisted of a deep deposit of soft oozy
muck, typical of most Adirondack lakes. In the littoral zone the
bottom consisted mostly of sand, gravel and boulders, with the
latter particularly conspicuous at the various jutties or points of land.
A narrow sand beach occurred at the extreme south end of the lake,
and a narrower one at the northern end. Both were important as
foraging areas for minnows and other small fishes including the
fry of small suckers.

The level of Wolf Lake was raised as much as three or four
feet about twenty years ago as the result of beaver activities. This
killed a narrow fringe of arbor vitae along both sides and more
expansive areas at each end, particularly those adjacent to the two
inlet streams that have been used by dwarf suckers for spawning
purposes . Beaver did not resume activity at Wolf Lake until this
study was completed. A small amount of speckled alder and a few
other woody plants at the north end of the lake did attract a small
colony in 1946. They erected a dam at the mouth of North Inlet
which was sufficient to prevent all but a few dwarf suckers from
reaching the spawning grounds.

The trees killed in the flooded zone at the south end of the
Lake were removed as a "clean-up" project in the C.C.C. work plan
three years prior to the completion of this study. This, seemingly,
had an adverse effect on the suitability of the stream as a spawning
habitat, because the population decreased decisively in subsequent
years. The aff^ected zone at the north end has been reverting to
forest and a considerable amount of cover already exists. The
spawning dwarf sucker population has steadily increased in this inlet
during the course of the study.

Acknowledgments. During the progress of the field work
the writer received cooperation and assistance from his colleagues
and various other individuals all of which is gratefully acknowl-
edged. Special thanks are due Mr. Oscar W. Oja, Supervisor of
the Huntington Forest, particularly for services rendered after
regular working hours and on legal holidays when other assistance
was unavailable.

FIELD METHODS AND TECHNIQUES

In fulfilling the purpose of the study data were obtained par-
ticularly on sex ratios, ages, spawning habits and migration, but in-
cidentally on any other phase of the life history, ecology and habits

90

Roosevelt Wildlife Bulletin

that might be forthcoming. Data of this sort are very essential in
establishing the ecological and economic relations of the fish with
reference to the general biota of the waters on the Huntington
Forest, as well as those of the entire Adirondacks and adjacent
regions.

Collecting in the Inlets. The dwarf >uckers were collected
mostly by means of a 4' x 6' common sense minnow seine, oper-
ated by one man (Fig. 19). A hundred or more individuals were
retained in a large bucket of water, and transported to a convenient
place nearby for study. The marked fish were put in a similar con-
tainer and when the batch was completed were released well down-
.-tream in uninhabited areas. Collecting was always progressive from
the lowermost to the upjjer pools. Very few dwarf suckers were
captured on the riffles — if these did not retreat to the pools of their
own volition, they were driven. Once within the pools the suckers
were reluctant to leave, so that eventually every individual was
collected with the seine.

Much of the success in capturing great numbers of dwarf
suckers can be attributed to the fact that the inlets of Wolf Lake
were well adapted for seining. The pools were practically free of
boulders, brush and other objects that reduce the efficiency of seines,
and furthermore there were no inaccessible hiding places.

Marking. The fi>h were marked by the clipped-fin method.
Since only the lower fins could be safely removed and a single fin
was to be removed each year, the marking was limited to five years.
The program started with the dwarf sucker breeding season of 1938,
and was continued without interruption for the specified five-year
period. As a matter of fact, recoveries on marked fish were ob-
tained in the 1943, 1944. 1945 and l94(^ seasons following the
conclusion of the original study.

During the first two years of the study, the dwarf suckers in
the two inlets were differentiated by the removal of entirely different
fins (right ventral and right pectoral on North Inlet fish, left ventral
and left pectoral on South Inlet fish). This was for the purpose of
determining, in subsequent years, the extent at which the instinct
for returning annually to the identical stream was developed. The
same fin (anal) was removed from fish of both streams the third
season, but during the last two seasons, the remaining paired fins
were removed in their respective order — right ventral or right
pectoral fin on ."^outh Inlet, left ventral or left pectoral fin on North
Inlet.

Unless the fins were clipped very close to the body of the fish,

Life History, Ecology and Habits of the Dx^'orf Sucker 91

they invariably regenerated. The extent of regeneration varied with
dif¥erent individuals and particularly in the manner of clipping.
Some fins were regenerated almost perfect except for a slight sug-
gestion of unalignment of rays at the point where new growth began.
Most regenerated fins were greatly malformed, stubby and with a
great amount of adipose tissue. The amputations were made with
ordinary fine-pointed dissecting scissors. The dwarf suckers recov-
ered during the second, and each succeeding, year were re-marked
in the same manner as those that were being marked for the first
time. This means that at the conclusion of the study some fish had
been divested of all five lower fins, others from one to four.

The sex of every fish was recorded as was its standard length,
special markings (such as scars and deformities) and color phases.
Scales for age determinations were removed from a sizable group
each season. Some of the scales, taken during the two years follow-
ing the regular program, were from fish that were definitely known
to have spawned six and seven years in succession.

The field party generally consisted of two men (one besides the
writer). The latter made all the measurements, determinations and
marking, while the helper had complete responsibility of recording
the data as dictated and supervised.

Only the standard length (length to end of vertebrae) was
taken, and this was recorded to the nearest quarter-inch. At first it
was quite difficult and time-consuming to keep the fish in position
for measurements. They would not lie flat, or they would slide out
of place on the slimy surface of the measuring apparatus. Both of
these problems were considerably solved as the study progressed.
The sliding was alleviated by placing one or more thicknesses of
moistened cheesecloth under the fish. Frequent changes were made
as the slime accumulated. Unruly fish could often be quieted with a
few gentle strokes of the finger tips along the sides or bellies. This
seemed to have a sort of hypnotic efifect similar to that described by
Hansen ('43) in the case of squirming eels.

In most cases there was no doubt as to the sex because the fish
frequently scattered sperm or ova while being prepared for the
measurements or during the amputation of fins. Even when this did
not occur, sexual dimorphism was sufticiently marked to warrant
proper sex determination.

Collecting in Wolf Lake. What happens to the dwarf suckers
when the}' return to Wolf Lake at the completion of the spawning
activities? Do those from the North Inlet (or South Inlet) move
freely from one part of the lake to the other, or do they remain in

92

Roosevelt Wildlife Bulletin

the deep water nearest their chosen spawning stream ? Netting
activities carried on during August 1941 were planned with the view
of obtaining data of this nature.

The catches were made by means of a trammel net which was
found to be more efficient than gill nets or other apparatus. Most
of the sets were made at right angles to the shore, but others were
made parallel to it, or across the neck of a bay. The first-mentioned
method proved to be the most valuable especially since the net was
long enough to extend from the littoral zone to a point into or
beyond the deepest area. The depth at which the greater number
were enmeshed in the net was considered indicative of the favorite
habitat for that particular time of year.

The netting program as originally planned was shortened some-
what to avoid undue losses of brook trout. It is believed, however,
that a sufficient number of sets were made to accomplish the intended
purpose. Most of the dwarf suckers, captured with the trammel
net, were still alive, and these were released after measurements and
other data had been secured. Those that were dead had become
hopelessly entangled in the meshes of the net. Brook trout sufifered
far greater losses in this manner than did the suckers. Common
suckers and a single bullhead and a few red-bellied sunfish were
the only other species taken on these test sets.

The netting operations in Wolf Lake yielded 106 dwarf suckers.
Strange as it may seem, exactly one-half of these had been marked
on one to three occasions during the previous four years' activities.
In analyzing the data a few rather significant trends are apparent,
but they lack sufficient supportive evidence to warrant definite con-
clusions.

First of all it she )uld be stated that most of the suckers captured
in the net were females, as determined solely from the size of the
anal fin — the only reliable external character at that season. Evi-
dently all fish less than seven inches in length were capable of pass-
ing through the 134 -inch meshes of the net. This would exclude
most males which, as revealed from the data obtained during the
spawning season, do not often exceed that length. The smallest
sucker taken in the net was seven inches — the largest was ten and
one-half inches, with the majority ranging from seven and one-half
to nine inches. Most of the fish were "gilled" in the region immedi-
ately anterior to the dorsal fin, which further indicates that those
slightly smaller would pass through without becoming snared.

The netting activities revealed that dwarf suckers and common
suckers have quite dift'erent habitats during the Summer. The former

Life History, Ecology and Habits of the Dwarf Sucker 93

were seldom found within the Httoral zone at that time of year, but
the latter were taken more frequently in such places than elsewhere.
This was not only true of Wolf Lake, but for the other lakes, as
well. Quiet bays, and other places where considerable emergent
vegetation prevailed, were particularly attractive to common suckers,
but barren insofar as dwarf suckers were concerned. The evidence
suggests that common suckers normally do not inhabit shallow water
for extended periods, but migrate into such places, especially at night,
possibly to obtain food. Dwarf suckers on the other hand apparently
obtain sufficient food in the deeper areas without subjecting them-
selves to possible enemy depredation that unquestionably would occur
in shallow water.

The data indicate that dwarf suckers in returning to the same
spawning streams each year did so from instinct or the result of
some special stimulus rather than the influences caused by environ-
mental conditions, as was formerly suspected. While there was a
slight tendency for fish to remain in that part of the lake nearest
to their accustomed spawning stream there was no well defined division
in the lake between the spawning individuals of the two streams. Thus
all the marked suckers recovered in the north half of the lake had
spawned in the North Inlet on one to three occasions, but those in
the mid-section and southward had representatives of both streams.
The distribution in the lake during the summer months appears to
be governed more by tolerance, and perhaps food supply, rather than
nearness to the spawning grounds. By far the greater number of
dwarf suckers spawn in the North Inlet, consequently when they
redistribute their numbers subsequent to the spawning season the
greatest shift is to the south or towards the area of minimum density.

Instinct appears to be a well developed characteristic of fishes
in general and yet it seems quite unusual in the case of dwarf suck-
ers where individuals from two spawning streams on directly oppo-
site ends of the lake meet on a common summer range only to
separate in the Spring and enter their respective streams. The few
individuals that migrated from one spawning stream to the other
in the space of a few hours certaintly accomplished an unusual feat,
and makes one wonder how such a change of habitat could be per-
formed so quickly. It would seem that these fish reached their
destination by means of some special sense or instinct rather than
by mere coincidence. Perhaps a combination of factors guided the
suckers across the lake to the proximity of the inlet, where a normal
response to incoming water was efifected.

There is reason to believe that dwarf suckers migrate shoreward

94

•

Roosevelt U'ildlife Bulletin

and enter the littoral zone at least ten days (probably much longer)
before entering the spawning stream. This was demonstrated very
well in Arbutus Lake, on the Huntington Forest. A trammel net
was set parallel with the shore at the outer edge of the littoral zone
late in the afternoon of May 9, 1942, about ten days before the
spawning season. Preliminary examination of the net the following
morning revealed that more than fifty dwarf suckers had been
captured and man\' more were ensnared before the net could be
removed. This particular site yielded an abundance of common
suckers but no dwarfs, in the same net operated during the pre-
ceding Summer.

The change of habitat prior to entering tributary spawning
streams is characteristic of other fish species, that inhabit deep water
during the summer months, i.e. pike-perch, Sticostedion vitrcum
vitreum (Mitchill), in Oneida Lake. Furthermore, there are reasons
for believing that many dwarf suckers even follow the example of
pike-perch by spawning in shallow water rather than in tributary
streams. This seems to be logical because the streams, in general,
have inadequate spawning facilities for so many spawning fish within
such a short space of time. In Wolf Lake, the available information
indicates that possibly only fifty percent of the suckers spawn in the
two streams and these utilize about all the suitable space. If the
population were much greater, the stream would be physically in-
capable of accommodating them.

DESCRIPTIONS
Mather's Description. The description of dwarf suckers as re-
reported by Mather (1890) is based on the type (No. 33918) and is
herewith quoted in toto because it is not readily available to others.
It must be recognized that Mather's description obviously is errone-
ous and incomplete in many respects and should be valued mostly
from the historical viewpoint. Mather listed the species as, "The
June Sucker, Catostomus utawana. Sp. Xovo. (L'tawana, name of
lake)".

"Body elongate and but little compressed, heaviest at shoulder
and tapering to tail, nearly cylindrical ; head moderately large, sub-
(juadrate. much flattened above : its length in body, four ; snout very
slightly prominent ; mouth nearly terminal, protractile upper lip with
two rows of papillae and continuous with the lower : the latter bi-
lobed and strongly papillose ; scales crowded anteriorly, but not larger
in the lateral line than those below ; sixty-seven in lateral line, nine
rows above and eight below ; lateral line straight, faint, obsolete in
spots ; length, exclusive of caudal fin, four and one-half inches ; eye

Life History, Ecology and Habits of the Divarf Sucker 95

in head, four : eye in snout, two : inter-orbital space in head, four.
Fins: Dorsal square, inserted in middle of body; rays, one, eleven;
its height equals its length. Anal: Five rays, third longest, reaching
to base of caudal; this ray is two and one-quarter times the length
of the fin. \'entrals inserted under fifth dorsal ray, nine rays, third
ray three times the length of the fin. Pectorals: Fifteen rays, reach-
ing nearly to the insertion of dorsal ; caudal deeply forked ; lobes
equal ; pharyngeal bones moderate ; lower, two teeth enlarged and
truncate."

Huntington Forest Dwarf Suckers. The dwarf suckers of the
Huntington Forest are herewith being described in considerable
detail and with particular emphasis on sexual dimorphism and major
differential subspecific characteristics. Investigation may reveal that
in the past certain species have been relegated to synonomy as a
matter of convenience or because of inadequate descriptions and
material. It is hoped that this description of dwarf suckers, there-
fore, will be useful in determining the taxonomic relations of suckers
in other regions.

Kendall and Dence ('29, pp. 281-287) in discussing the family
Catostomidae call attention to the need of a revision of the genus
Catostoiinis. They state (p. 284) that "We are almost ready to be-
lieve that the proper relation of species in the East has not been
recognized and that some species have been relegated to synonomy".
It was suggested that the solution to the geographical distribution
of the genus might be solved on the basis of "at least three postglacial
distributional trails leading northward and eastward" with the "Mis-
sissippi forms dififering from the Atlantic seaboard and the Great
Lakes suckers. It is a probable fact some of the more southern
forms have geographically overtaken some of the northern and inter-
mediate forms on the distribution trails."

This theory is substantiated in part by the collection of suckers
from the Allegheny and Chemung watersheds of New York in which
Greeley ('38) found two recognizable forms, although currently re-
garded as one. He states (p. 63) that an "Examination of large
numbers of specimens showed that the sucker population of the area,
although currently regarded as conforming to the one subspecies, is a
composite of two, recognizable forms. These appear to be split by
watershed lines, the Allegheny system having a distinct form, probablv
representative of the middle Western fauna. The chemung area
suckers are like those of other Atlantic coast drainage rivers in having
a large mouth and certain differences in snout proportions and other
characters which will require further study for exact delimitation."

96

Roosevelt WUdlife Bulletin

Sixty-four preserved dwarf suckers, including 46 males and 18
females, collected at various times and more or less at random were
used in acquiring data for the following description. Since there was
some variation between sexes it was considered best to treat them
separately in certain respects especially in regard to comparative mea-
surements. The males used in these compilations averaged 132.9 mm.,
the females 158.6 mm.

Males Females

Head in standard length 3.8 3.7

Head in total length 4.5 4.4

Depth in standard length 5.2 5.0

Depth in total length 6.0 5.8

Snout in head (average) 2.08 2.10

Distance from snout to dorsal fin in standard length 2.0 2.0

Average length longest ray of ventral fin (mm) . . . 19.96 19.59

Average length longest ray of ventral fin (mm) . . . 19.% 19.59

Average length dorsal base (mm) 21.5 23.4

Length dorsal base in standard length 6.1 6.8

Distance from anal fin to lower lobe of caudal in

standard length 7.2 6.7

Length caudal peduncle in standard length 11.7 10.5

Depth caudal peduncle in standard length 11.1 10.5

Eye in head 6-7* 6-7

Average length longest ray of pectoral fin (mm) . . 25.2 28.2

Snout to base ventral in standard length 1.8 1.8

Distance from ventral to anal in standard length

average 5.3 4.9

* 6 in small specimens, 7 in large.

Color. Dwarf suckers are rather sombre colored except during
the breeding season when they rather suddenly acquire much pig-
mentation. On May 8, 1942, about a hundred dwarf suckers captured
well in-shore in Arbutus Lake had neither pearl organs or the distinc-
tive colorations of breeding fish. While the spawning date was not
determined for suckers in this lake that particular season, it undoubt-
edly began a week or ten days after the above observation (the dates
on which spawning began in other waters on the Forest). If the
suckers captured in Arbutus Lake on the above-mentioned date
spawned that season they must have undergone a seemingly impossible
transformation within a brief period for when dwarf suckers enter
the spawning streams all but a limited few, and these mostly females,
have acquired the typical nuptial features.

This subspecies differs from common suckers in that their breed-

Life History, Ecology and Habits of tlic Dwarf Sucker 97

ing colors remain fairly constant during the spawning season, even
when removed from water and subjected to various treatments. There
were no sudden changes in color such as customarily exhibited by
common suckers under similar circumstances. Reighard ('20, p. 6)
describes the sudden color changes that common suckers undergo
when stimulated by fear coincident with capture. He states that these
changes mav be accomplished within a few seconds. Hankinson ('19,
p. 136) also notes that breeding suckers which he observed in lUinois
"lost their intense black markings instantly" on capture. The writer
observed that the broad blood-red stripe on the sides of breeding
dwarf long-nosed suckers, Catostoinits catostomits nanomyaon
Mather, captured at Cranberry Lake began fading witliin a few sec-
onds after the fish had been removed from the water, and had dis-
appeared almost completely at the end of fifteen minutes or so. The
black pigment, however, was little af¥ected.

The color pattern of breeding dwarf suckers, and particularly
that of males, is very distinctive, and makes it possible for one to
readily distinguish these fish from associated species in the same
stream, even at considerable depths. Perhaps the most conspicuous
feature is a light olive-green stripe, three to four scale-rows wide, and
extending the entire length of the fish, located in the dorso-lateral
region. This stands out in bold contrast by virtue of its position be-
tween the darker and somewhat mottled coloration of the dorsal region
and a jet-black stripe along each side, which includes the upper half
of the lateral line series of scales and, usually, three additional rows.
This black stripe extends across the opercles and cheeks to the anterior-
most end of the snout.

The sexes of breeding dwarf suckers sometimes are indistinguish-
able by color alone, but frequently the females are quite uniformly
olive-colored above and without any distinctive markings. Occasion-
ally one may detect a faint rosy tint anteriorly along the lateral line.
Likewise some individuals have a decidedly bronzy appearance.

A series of five blotches of dark pigmentation occurs on the sides
of most individuals. These are rather conspicuous on small highly
pigmentated males, but scarcely apparent in females and some of the
larger males. One of these blotches covers most of the surface between
the operculum and the preoperculum. Another occurs near the base
of the caudal fin and the remaining three are quite evenly distributed
along the side, but mostly ventral to the lateral line. The pigmentation
does not extend dorsally beyond the lateral line series of scales, and
includes onl\- two or three rows of scales below the lateral line.

Unusual Color Phase. A few individuals were distinguished from

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Roosevelt Wildlife Bulletin

all others by certain abnormalities such as a curved spine, lack of gill
cover, extra fins and the like. These characteristics when considered
in connection with the number and position of removed fins made iden-
tification certain. There was an occasional fish on the spawning beds
each season that could be identified positively from its peculiar colora-
tion when considered with other markings. While we recorded this
as "pink" actually the color was more purple than pink. The entire
body was afi'ected, but the color was more vivid on the ventral side in
the head and thoracic regions. There was also a suggestion of trans-
parency in their appearance. One of these unusually colored suckers
first appeared in the 1940-season. It returned the following season,
was relieved of another fin and thereafter was captured at the upper
end of the spawning area on several successive days. This same fish
returned to the spawning stream in 1942 — the third consecutive season.

Hansen and Shoemaker ('43, p. 54) describe a peculiar color
phase of carp and carp-suckers, due to pigment deficiency, apparently
comparable to that of the dwarf suckers described above. They men-
tion that "The skin of the abnormal one has a transparent appearance
with a purplish brown color showing through the scales . . . This
pigment abnormality is probably genetic rather than a diseased condi-
tion since the specimens appear plump and otherwise in good health.''

None of the peculiar colored dwarf suckers have been recovered
in the lake proper, therefore it is not known whether the lack of pig-
mentation persists throughout life or is merely a secondary sex char-
acter apparent only during the spawning season. The fact that certain
individuals exhibit this color phase annually while on the spawning
grounds suggests that it is permanent. If that is the case one might
expect the coloration to be less vivid outside of the breeding season,
because even normally colored individuals lose much of their pigmen-
tation during that ]>eriod.

Si::e. Dwarf suckers show considerable variation in size even
within the same watershed. This is demonstrated very well in tlie
lakes of the Hvmtington Forest, all of which are in the same drainage
system. The dwarf suckers of Wolf Lake are decidedly smaller than
those of Catlin Lake which in turn are slightly smaller than those of
Rich Lake. Those in Arbutus Lake are about the size of the Wolf
Lake dwarfs.

It appears that Mather (1890) encountered a smaller strain in
the Blue Mountain Lake region since he gives the standard length in
his description as only four and one-half inches and mentions in the
discussion that "it barely reaches five inches". No mention was made

Life History, Ecology and Habits of the Dwarf Sucker 99

of sexual differences and it is to be assumed that both males and fe-
males were included in the computations. If that was the case his fish
must have been decidedly smaller than those considered in this report.

Kendall and Dence ('29) give the range in lengths of dwarf
suckers in the Cranberry Lake watershed as four to six inches, which
is comparable to the Wolf Lake population. Greeley and Greene ('31),
Greeley and Bishop ('32) and Greeley ('34) do not mention the sizes
included in their collections from the Adirondacks. They specify the
size as "small" in each instance.

Table 3. Summary of Standard Lengths of Dwarf Suckers
(in Inches), Showing Averages, Maximum and Minimum
BY Sexes

Year

Total No. Fish
(Recoveries
included)

Average
Standard
Length

Largest Fish
Standard
Length

Smallest Fish
Standard
Length

Males

Females

Males

Females

Males

Females

Males

Females

1938

1,634

362

5.218

5.958

8.00

8.50

4.00

4.75

1939

1,799

825

5.237

6.015

8.00

10.50

3.50

4.50

1940

2,074

1,127

5.039

5.878

8.25

11.00

3.25

4.00

1941

3,596

662

4.890

5.701

8.25

8.75

3.75

4.25

1942

4,165

1,065

5.017

5.623

7.50

8.00

4.00

4.50

A summary of standard lengths of dwarf suckers from Wolf
Lake is given in table 3. It will be noted that the females from
season to season throughout the five-year period averaged about
three-fourths of an inch longer than males. Casual observation in
the field, however, gave the false impression of a much greater
difference in average lengths of the sexes because there were always
a few large females on the beds. The annual influx of a good many
small females toward the end of the spawning season, of course,
lowered the average size for the year by a considerable amount.
While small males likewise, were, more in evidence late in the
spawning season, the average was not reduced in the same propor-
tion because of the relatively greater seasonal total.

The difference in size of the sexes becomes apparent, in fishes
of the same age-class, early in their existence and certainly before
attaining sexual maturity. Female dwarf suckers experiencing their
first reproduction period usually are one-half to one inch longer than

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Roosevelt Wildlife Bulletin

males of corresponding sexual status. The discrepancy becomes more
pronounced later in life and in a few instances may become as much
as two or three inches.

As indicated in table 3 the smallest male taken on the spawning
bed was only three and one-fourth inches in standard length, and a
considerable numljer were under four inches. No females were
found under four inches and very few less than five inches. An
occasional male had attained a length of seven inches or longer, but
the general run, as may be concluded from the averages, was be-
tween five and six inches. The rate of growth prior to sexual
maturity is fairly rapid, but it is very slow thereafter. Males that
had been captured on seven successive years were as small as 5^
and 6^4 inches, indicating that only two or three inches had been
added to their length during that period. A 3^-inch male marked
Alay 21, 1941 and recaptured May 24, 1944 had grown only one and
one-fourth inches in the three-year interval. The extremely slow
growth of adults complicates the problem of correlating ages with
annual growth.

Pearl Organs or Tubereles. Kendall and Dence ('29) in their
Cranberry I.ake studies observed that one of the dififerences between
dwarf suckers and common suckers was that breeding females of
the former were equipped with effective pearl organs which are said
to be absent or of rare occurrence in the latter. These authors state
(I.e., p. 289) 'Tn most cases these organs were not as fully developed
on the females as on the males, but in some cases they were much
alike, so that careful examination was necessary to determine the
sex from external features. The pearl organs on the scales of the
females posterior to the dorsal fin were more pronounced than those
on the males. Some of our female specimens have pearl organs on
the anal and lower caudal fins as large as those of the males, al-
though it appears that these are exceptional cases."

These observations on dwarf suckers at Cranberry Lake agree
very well with those of the writer for this species on the Huntington
Forest. The combined data indicate that the two subspecies, while
very similar in man}' respects, are decidely distinct in others. Ac-
cording to most authorities pearl organs characteristically do not
occur on breeding female common suckers. Hankinson ("19, p, 436),
however, reports that small pearl organs were found on two female
common suckers in a collection of spawning suckers captured near
Charleston, Illinois. Reighard ('20) gives a detailed description of
pearl organs on spawning male common suckers, and concludes his

Life History. Ecology and Habits of the Dzcarf Sucker 101

remarks by stating that "pearl organs do not occur in the female".
Likewise Fowler ('12, p. 474) in examining the pearl organs of
breeding fish failed to find any on female common sukers.

Pearl organs occur on the scales and fins of both sexes of dwarf
suckers. In general, though not always, these structures are weaker
and less conspicuous on the females than they are on the males.
The scales below the lateral line posterior to the vent and particu-
larly adjacent to the base of the anal fin, are thicker and more
heavily studded with pearl organs on the females than on the males.

Usually all of the scales on the males with the exception of
those on the belly have one or two round or cone-shaped pearl
organs on their distal portion. Some individuals have pearl organs
on part or all of the ventral scales. The lateral line series of
scales usually are armored with two pearl organs on each scale — -
one above and one below the pore. While the other scales usually
have but one pearl organ, scattered individual scales have two and
in a few instances three. The dorsal side of the head from the
region of the occiput to the papillae of the snout is rather profusely
covered with minute pearl organs. They frequently extend well down
the sides on the cheeks and opercles, and may even occur on the
branchiostegals.

Most of the scales dorsal to the lateral line in females have
pearl organs although many of these are so small and weak that they
are discernible only when magnified. As in the case of the males,
these structures are more profuse on the head, although they become
inconspicuous or absent near the snout. There is considerable indi-
vidual variation among females with respect to the number and size
of pearl organs on the scales adjacent to the caudal fin. Those on
the ventral side of the caudal peduncle are sharply pointed similar
to those of the males.

Conspicuous pearl organs occur on every ray of the caudal fin of
males. The longest and strongest occur on the lower lobe, but these
taper in size to the fork. Those in the upper lobe gradually decrease in
size from the fork upward. The pearl organs near the base of the
fin are larger than those at the posterior margin. There is consider-
able individual variation in the number and arrangement on the
caudal fin of females. It can be stated, however, that only the lower
half of the fin supports pearl organs and these are more numerous
but smaller than those on the males.

Every ray on the anal fin of males supports pearl organs
throughout its entire length. These occur in a single row on both

102

Roosevelt Wildlife Bulletin

sides of the various branches as well as the basal portions and they
are rather large and sharp. Regenerated anal fins usually possess a
few pearl organs although these are likely to occur as elongated
' ridges rather than distinct sharply-pointed cone-like structures. The
pearl organs on the anal fin of the females are limited principally
to the three longest rays and mostly to the basal rather than the
distal portions. Usually not over five or six occur per ray and they
are typically smaller than those on males. It is not unusual, however,
to encounter females with pearl organs on the anal fin as large as
those on males.

The distal half of the ventral fin of males contain very small
but (usually) sharp-pointed pearl organs. Most males have these
on both surfaces, but they are larger and more numerous on the
upper surface. The ventrals of the females are usually unarmored.

The pectoral fins of males support pearl organs. These are
particularly noticeable on the ray branches of the upper surface. If
present on the lower surface they are likely to be quite small and
inconspicuous. They are absent on females.

Both sides of the dorsal fin of males usually are with pearl
organs. Some males are practically devoid of these structures and in
cases where only a few occur they are rather small. Females gen-
erally have no pearl organs on the dorsal fin.

The abundance and distribution of pearl organs on both sexes
appear to be determined to a considerable extent by their general
health. Vigorous highly pigmented individuals usually are better
equipped with pearl organs than those that are more sombre-colored,
and less vigorous. This is well exemplified by a six-inch male in
the collection of preserved fish. Pearl organs are quite normal in
number and size on the anal and caudal fin, but are small and poorly
represented on other parts of the fish. Examination revealed that
this specimen harbored two large ligulas (Ligula intestitialis) in his
body cavity. The spermaries were sub-normal in size. Maximum
development occurred on small or medium-size males.

Scales. Similarly as with common suckers, dwarf suckers ex-
hibit considerable individual variation in the number of scales in the
lateral line. It may be stated, however, that the average is some-
where between 65 and 70, probably about 68. As few as 64 and as
many as 73 have been counted. The number of rows, on the other
hand, remains rather constant, there being ten above and nine below
the lateral line.

While the scales before the dorsal fin of dwarf suckers appear

Life History, Ecology and Habits of the Dwarf Sucker 103

to be smaller and consequently more numerous than those before
the dorsal of common suckers, actually there are only thirty on
most specimens. A good man}- individuals were examined and in
no case were there as many as thirty-five and certainly not "over
thirty-five" as have been reported by others (Greeley and Greene,
'31; Hubbs and Lagler, '41).

Greeley and Greene ('31, p. 84) state that common suckers
"from Adirondack waters of the drainage have smaller scales (the
scales from nape to dorsal fin being in about 30 rows)". The com-
mon suckers collected at the Huntington Forest, likewise, contained
30 rows of scales before the in.sertion of the dorsal fin — the same
number as the dwarf suckers. It must be concluded therefore that
the two Adirondack forms cannot be distinguished subspecifically
by means of this criterion. If common suckers in other regions have
as few as 25 scales before the dorsal fin as they undoubtedly do,
there would be added justification for a complete revision of the
genus. The problem becomes more complicated by virtue of the fact
that dwarf suckers have been reported by other authorities as having
smaller scales in the region before the dorsal fin than those on the
Huntington Forest.

The lateral line is extremely variable. In general it extends in a
straight line, but the scales are sometimes so arranged that an offset,
equivalent to the depth of one scale above or below the regular
straight course, takes place. Interruptions are common, particularly
in the posterior half, and the last five or six scales are likely to be
without pores. These observations are in accord with those made
by Kendall and Dence ('29) on Cranberry Lake dwarf suckers.

Fins. The height of the dorsal fin usually is slightly less than
its length. This is particularly true of females and large males. In
some of the small males, the height and length of the dorsal are
about equal. Since Mather (1890) gives the height as equal to the
length, he undoubtedly measured only small males.

The dorsal fin generally has eleven branched and one unbranched
rays. Occasional specimens are found, however, with only ten
branched rays. The anterior rudimentary (unbranched) rays were
not counted because they were not clearly distinguishable. The last
branched ray was divided to its base as in the case of common
suckers. This fin is inserted at about middle of standard length.

The caudal fin is deeply forked with the upper lobe often slightly
shorter than the lower lobe.

There are seven rays in the anal fin instead of five as reported

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Roosevelt Wildlife Bulletin

by Mather. The third ray is longest and, in the male, reaches the
base of the caudal. Females, have a slightly shorter anal fin. In
comparing anal fin lengths of similar size males and females it was
found that there was actually a difiference of four to six millimeters
— sufficient to be obvious even on casual observation. While the anal
fin of both sexes is equipped with pearl organs, those of the male
are longer and stouter.

The ventral fins are slightly nearer the base of the caudal fin
than to the anteriormost end of the snout. The point of insertion
thus is directly Ix-low the mid-region of the dorsal base — about as
stated by Matlier. The third, or longest ray, in fisli of comparable
lengths is 4 to 5 millimeters longer in males than in females. Thus
the ventral fins of a male 148 millimeters in standard length, for
example, would be about as long as those of a female 185 milli-
meters in length. The difiference in size may appear to be rather
insignificant, but really is of sufficient magnitude to be recognizable
on casual observation when the fish are close at hand. Reighard
('20, p. 7) mentions the greater length of the lower fin of male com-
mon suckers, but rightfully does not consider this diflferential char-
acteristic so striking as certain others.

The pectoral fins have seventeen ra} s. The innermost rays are
shorter than the others, and are not clearly discernible except under
magnification. Mather's count of only fifteen rays may have been
due to lack of magnification.

A number of dwarf suckers were encountered during the course
of the field work that either had more than the usual complement
of fins or had fins that were quite abnormal. One six-inch male
had an extra fin on the right ventral side of his body about midway
between the pectorals and the ventrals. While it was as long as a
regular ventral fin it contained only two, but very stout, rays. An-
other five-inch male had an extra fin of seven rays attached to the
caudal peduncle ventrally to the caudal fin. It was partly attached
also to the lower lobe of the caudal at its base. It extended down-
wards and backwards similar to the anal. Strangely enough it was
quite profusely covered with pearl organs. The caudal fin was nor-
mal in every respect except position — the extra fin had crowded it
upwards. The anal fin was larger than normal so that the last few
rays overlapped on the extra fin. There was a space of only 5 mm.
OD the caudal peduncle between the anal fin and the extra fin.

Both pectoral fins on a six-inch female were very short and
stubby — scarcely one-half normal size. In fact they were only one-

Life History, Ecology and Habits of the Dwarf Sucker 105

half inch long and contained but three rays each. A four and one-
half-inch male was minus the left ventral fin and from appearances
had always been so. The right ventral was scarcely half normal
length and contained only four rays. Another male, four and one-
half inches long, had his pair of ventral fins emerging from a com-
mon point on the median ventral line. The fins were joined in a
narrow plane along the middle ray giving the appearance of an "x"
arrangement for the combination.

COMMON SUCKERS AND DWARF SUCKERS IN THE
SAME HABITAT

Both gill nets and trammel nets were used in collecting fish in
the lakes of the Huntington Forest, but the best results were ob-
tained with th.e trammel net. If the collections obtained with the nets
are indicative of the distribution, it would then appear that dwarf
suckers and common suckers occupy quite different habitats within
any particular body of water, at least during the summer months.
Common suckers have a strong predilection for the littoral zone par-
ticularly where gross vegetation occurs in moderation. Their pres-
ence in this type of habitat possibly may be due to l^etter foraging
conditions rather than to other factors. If such is the case, periodic
(possibly daily) migration from deep to shallow water or vice versa
undoubtedly takes place. The fact remains that very few were
captured in deep water.

Dwarf suckers often encroach upon the outer edge of the littoral
zone, but normally they remain within the deeper areas except during
the breeding season. Deep water possibly may ])e the principal
prerequisite responsible for their distribution in the Adirondacks.
The fact that they occur in all the lakes of the Huntington Forest,
except Deer Lake, which is surprisingly shallow (maximum depth
of 10 feet) gives added support to this theory. It also supports the
contention that common suckers and dwarf suckers are sufficiently
dissimilar to justify their differentiation subspecifically.

Considering its size. Wolf Lake has a proportionately greater
population of dwarf suckers compared with common suckers than
any other lake on the Forest. During the seven successive days in
which the trammel net was operated in the lake early in August,
1941, a total of 106 dwarf suckers and six common suckers were
captured. A small portion of the net in each of the sets was within
the littoral zone. Several years previously (1934), sets placed com-
pletely within that zone yielded only common suckers.

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Roosevelt Wildlife Bulletin

At the conclusion of the netting activities in Wolf Lake, in 1941
the same nets were moved to Arbutus Lake, and operated in similar
manner for five successive days, after which they were taken to
Rich Lake for seven days. Only one set was made in the deepest
part (26 feet) of Arbutus Lake, and it was the only one that yielded
dwarf suckers. Common suckers were abundantly represented in
each of the other sets. Similar results were obtained in Rich Lake.

During the course of the study five or six large female common
suckers were taken on the spawning beds of dwarf suckers in the
North Inlet of Wolf Lake. They were extremely shy and unruly —
causing so much disturbance that it was necessar\- to remove them
to prevent the dwarf suckers from becoming unduly excited. They
were never observed mating with dwarf suckers. In a small inlet of
Rich Lake v.here both forms were represented the dwarf suckers
remained within a small section of riffles and did not associate with
common suckers, which were further upstream in relatively deep and
quiet pools. (See Figs. 23 and 24.)

SPAWNING MIGRATION

The dv/arf suckers of Wolf Lake at the Huntington Forest al-
ways spawn during the latter part of May, sometimes extending the
period a few days into June. During the first three years of the study
(1938-1940 inc.), the first group entered the streams on or about May
25, but the following two years, (1941 and 1942), the season began
about May 15. In 1943 spawning seemed to be at its peak when a
census was made on June 1, indicating that the suckers probably had
entered the streams four or five days previou.sly. In each of the above-
mentioned years, the fish appeared in considerable numbers from the
very beginning and within two or three days had reached the peak of
their population on the spawning grounds. The decline in population
was less abrupt because a few individuals, mostly young fish possibly
spawning for the first time, did not enter the stream until many of the
early arrivals had finished spawning and had returned to the lake.

Another check was made on spawning dwarf suckers in May,
1944. A single fish was observed in the South Inlet of \A'olf Lake on
the evening of ]\Iay 18, but it was evident that the prevailing sudden
drop in atmospheric temperature would have a deterrent eltect on the
spawning activities. This proved to be the case for the population re-
mained very low for the succeeding five days — fluctuating with the
rise and drop of the temperature in the inlet irrespective of the time
of day.

Life History, Ecology and Habits of the Dicarf Sucker 107

A census of dwarf suckers in this stream at 11 A. M. on May 24,
after the atmospheric temperature became stable and more normal,
accounted for 270 fish on the spawning beds. Judging from events of
past seasons, the peak of the run would have occurred three or four
davs later.

There was a distinct correlation between the dates on which the
ice left the lake and the dates marking the start of the spawning migra-
tion. In the 1941 and the 1942 seasons, the "break-up" occurred about
two weeks earlier than it did in the other years, consequently migration
began about that much earlier. The weather during both of these years
was unusual for the Adirondacks region. In 1941 the last snowfall
occurred on March 21, and there was no snow on the ground after
April 12. The following winter was characterized by an extremely
subnormal amount of snow (there never was more than two feet at
any one time, and the ground was bare by April 14). Normally the
lakes of the Huntington Forest are covered with ice in Mid-April, and
there are several feet of snow, possibly subzero temperatures, with no
indication of the spring break-up.

The following table (Table 4) shows spawning migration dates
of dwarf suckers at Wolf Lake for seven years beginning with 1938,
and the dates for each of these years on which the ice left the lake.

Table 4

Year

Date on which Ice left Lake

Spawning Migration Date

1938

May 1

May 25

1939

May 5

May 25

1940

May 4

May 25

1941

April 19

May 15

1942

April 20

May 15

1943

May 9

May 25 (?)

1944

May 4

May 18-19

As indicated in table 4, spawning migration occurs about three
weeks after the ice leaves the lake. Slight variation in air temperature
from year to year naturally accounts for at least a portion of the differ-
ence in time. The spawning dates of dwarf suckers for the other lakes
at the Huntington Forest do not coincide exactly with those of the
Wolf Lake suckers.

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Roosevelt Wildlife Bulletin

Dwarf suckers breed at a later date in certain other sections of
the Adirondacks for Greeley ('34) found them spawning in the cold
inlets of Lake Eaton "as late as June 19", while Greeley and Greene
('31) observed spawning on June 14 in a tributary of the Lower St.
Regis Lake. The 1934 season at the Huntington Forest was somewhat
later than was the case during any of the five years of the present
study. Fish were still breeding on June 7 of that year, although the
season was in its final stages.

Migration from Wolf Lake to the spawning streams was never
observed, but the collecting data show that, normally, it takes place at
night. On one occasion (April 21, 1941), there was definite proof
that considerable inimbers of suckers were entering and leaving the
South Inlet of Wolf Lake throughout the daylight hours. This stream
was seined very thoroughly in the morning and there was no question
but that practically every fish (forty individuals) was collected and
marked. By late afternoon most of those previously marked had left,
and an entirely .diflferent group of about eight fish had taken their
place. This was a rather unusual circumstance, however, which may
be attributed partially, if not wholly, to disturbances and reactions
brought about by high atmospheric temperatures, together with heavy
precipitation. The maximum temperature recorded on that day was
86 degrees F, and 1.8 inches of water fell within a 24-hour period.
The volume of water in this stream about doubled within a few hours,
and the velocity likewise increased markedly. The water was suffi-
ciently deep at the mouth of the stream to make ingress and egress of
fish unnoticeable.

There were occasions when suckers were suspected running into
the North Inlet of Wolf Lake in the daytime, and especially on rainy
or cloudy da} s. But this stream was much larger and more diversified
than the South Inlet, and consequently provided a better spawning
haljitat for the dwarf suckers, particularly during adverse weather
periods. It would have been difticnlt and perhaps quite impossible to
observe suckers migrating from the lake under such circumstances.

Raney and Webster ('42) observed that common suckers , mi-
grated mostly at night in Skaneateles inlet. The migration "started at
dusk and continued with greatest intensity up until 10 or 11 P. M. '
They found that some of the common suckers went no farther up-
stream than a few hundred yards, but that some as far as four miles.
The dwarf suckers of Wolf Lake inlets were limited to less than one-
eighth mile, due to physical obstructions. In the North Inlet, fre-
quently large numbers stopped for a few hours or even a full day in

Life History, Ecolog\ and Habits of the D'a'arf Sucker 109

a deep pool, concealed with brush, near the lake before proceeding to
the spawning riffles.

It was not unusual to observe considerable numbers of fish in the
act of migrating upstream throughout the daytime, although this phe-
nomenon was more pronounced late in the afternoon. At least some,
and possil^ly a considerable amount of this activity may not have been
strictly normal because many of the fish involved had been captvu-ed
on the spawning riffles earlier in the day, and later released several
rods below these riffles. The few individuals that could be identified
by abnormal markings were observed to re-migrate upstream to the
spawning riffles until spent, regardless of the number of times they
were transported downstream.

In the early part of the 1944 season observations made at night
in the South Inlet, with the aid of a flashlight, revealed that at times
most of the dwarf suckers were migrating to the lake, rather than from
it. This was probably due to the sudden drop in atrriospheric tempera-
ture and the corresponding drop in the temperature of the water in
the stream, but with only a minor change in the lake itself. It appeared
as if the urge to spawn was present, but could not be consummated
because the habitat suddenly had ceased to fulfill the requirements.
The suckers remained in the inlet when the weather became milder,
and spawning was then much in evidence.

The principal spawning migration of dwarf suckers has never
lasted more than two weeks at Wolf Lake, or at any other lake in the
vicinity. In certain years all but a few stragglers left the spawning
areas within ten days after the first arrivals entered the stream. In
contrast to this, Raney and Webster ('42) found that the run of com-
mon suckers in Skaneateles Lake inlet extended over a seven weeks'
period in 1939. although the main run occurred about two weeks after
the first individuals appeared in the stream.

The dwarf suckers of Wolf Lake apparently never encounter
any serious difficulty in making their annual spawning migration into
the inlets. Throughout the period of this study the fish always found
it possible to enter the inlets freely. Whether all the dwarf suckers of
Wolf Lake utilized the stream for spawning is unknown. Possibly
some of them found suitable spawning areas within the lake proper.
If such was the case, then migration from deep to shallow water would
be expected.

The inlets of Arbutus Lake, on the Huntington Forest, have never
provided ideal spawning facilities for dwarf suckers. In fact the
species was found in only one of its inlets (Fig. 22), and even that

no

Roosevelt midlife Bulletin

stream generally failed to provide the desired qualities, and it was not
utilized for spawning purposes during such times.

On May 8, 1942 a small-mesh trammel net placed parallel with
the east shore, at a depth of 5 to 10 feet, yielded more than a hundred
dwarf suckers during the night and early morning, and all had entered
from the lakeward side, indicating that a shoreward migration was in
progress, possibly for spawning purposes. This was not the normal
summer habitat for dwarf suckers, and they were not taken there with
this type of net at other seasons. The same set usually yields mostly
common suckers and bullheads. The dwarf sucker population of
Arbutus Lake is so great that only a small portion could possibly
spawn in the inlet, consequently the others must spawn elsewhere. The
situation in certain other lakes is quite comparable to that of Arbutus
Lake.

Although common suckers are closely related to dwarf suckers,
their spawning migration habits are somewhat different, at least in
the waters of the Huntington Forest. The principal difference is the
fact that common suckers migrate into the tributary streams to a
very limited extent to spawn and there is little semblance of concen-
trated groups such as occurs with dwarf suckers. Small groups of
spawning fish have been observed in the inlet of Arbutus Lake and
in the pools at the base of the concrete dam spillway on Military
Lake (Fig. 24). Likewise, an occasional large common sucker enters
the North Inlet of Wolf Lake along with the dwarfs. Investigations
indicate that common suckers are about as numerous as dwarfs in
the various lakes. Certainly they must spawn somewhere, therefore
it may be assumed that spawning is accompHshed in the lakes.

Reighard ('15, p. 225) has observed that when common suckers
spawn in the stream the principal requirements are swift water and
gravel bottom. He believes that suitable bottom is more essential
than running water, and that in lieu of suitable streams, the major
portion of suckers may breed in the lakes. The lakes on the Hunt-
ington Forest are characterized by extremely soft, oozy bottoms
everywhere, except on the shoals. It seems obvious, then, that both
the dwarf and the common suckers migrate from deep water to the
shoals if and when they spawn in lakes.

The speed at which dwarf suckers, or other fish species, migrate
is difiicult to determine, especially where most of the migration occurs
from deep to shallow water, or from lakes to streams. Published in-
formation on this phase of the life history of the common sucker is
practically non-existent and of course totally absent for dwarf suckers.

Life History, Ecology and Habits of the Dwarf Sucker 111

The following data on migration were obtained during the course of,
and incidental to, the other studies on dwarf suckers. They are here-
with presented as a basis for future contributions.

Upstream migration of dwarf suckers was comparatively slow,
particularly where natural obstructions were sufficiently great to im-
pede progress. The number, size and effectiveness of the obstructions
as barriers had a direct bearing on the forward progress of the suckers.
Normally, migrating fish rested a few minutes or even a few hours in
quiet pools after negotiating an obstruction. Most of the obstructions
in the Wolf Lake tributaries caused no serious handicap in reaching
desirable spawning grounds. The suckers never were observed in the
act of attempting to negotiate the dam at the upper limits of the spawn-
ing area in the North Inlet, which obviously was slightly too high to
surmount. Possibly if desirable spawning areas had not been available
elsewhere the suckers might have attempted to get beyond this obstruc-
tion. As a matter of fact the dam was obliterated during the freshets
following the winter of 1943-1944 and the suckers subsequently ex-
tended their spawning grounds several yards farther upstream. Such
is frequently the case in other streams inhabited with spawning dwarf
suckers.

An example of an obstruction representative of the type that
could be considered about the extreme upper limit of what can be
surmounted was found in the inlet of Arbutus Lake on June 1, 1943.
Dwarf suckers were observed in the act of climbing the falls produced
by an abrupt rock-ledge with a sheer drop of about two and one-half
feet and with a moderately fast current of water three to four inches
in depth (Fig. 22). Several hundred suckers had assembled in the
pool immediately below the dam. The writer watched the activities
from a well concealed vantage point for about fifteen minutes, but
failed to see any fish make the falls although numerous attempts were
nearly successful. A very limited number of fish had been successful,
however, and these were observed on the spawning beds above the
falls.

Dwarf suckers like many other species of fish seem to have con-
siderable endurance because they are capable of migrating long dis-
tances within the lakes proper when the occasion demands. This was
demonstrated very well at Wolf Lake during the 1941 and 1942 sea-
sons. Twenty-one male dwarf suckers migrated from the South Inlet
to the North Inlet, or vice versa, a distance of slightly more than a mile,
within the current spawning season. Some of the records compiled
during the study clearly indicate that a few individuals travelled from

112

Roosevelt Wildlife Bulletin

one end of the lake to the other within a single night. A number of
other suckers made this same shift within two or three days. The
time could not be determined more precisely except in the first instance
because of the limitations of the marking system. It was reckoned
from the earliest date on which they could possibly have been captured
and marked that season. Thus in the 1942 season studies were not
made in tlie South Inlet of Wolf Lake until late in the afternoon of
May 21. The following morning a 4%-inch male bearing a recently
inflicted mark indicative of that stream was found in the North Inlet.
Others were found in like manner on succeeding days, but after the
first day there was no way of determining on what day they had been
marked.

All but one of the twenty-one suckers guilty of changing their
spawning stream within the current season had been marked originally
in the South Inlet. This stream seemed to have lost its appeal as a
.spawning habitat during the last two years of the study due, perhaps,
to the removal of certain cover by the C.C.C. or adverse weather con-
ditions. That unsatisfactory conditions prevailed there is substantiated
somewhat by the fact that during the last two years of the study the
records reveal that many dwarf suckers failed to return to the spawn-
ing area after being released downstream, near the lakeshore, at the
conclusion of the marking procedure. This reaction apparently cannot
be considered a res^wnse to repeated annual disturbance by the writer
since the dwarfs in the North Inlet were treated in similar manner
without exhibiting this phenomenon. The North Inlet was by far the
more desirable, as a spawning habitat than the South Inlet. There
was one (possibly two) instance of this type of migration during the
first three years of the study, but records were not made because it
was the belief that an error had been committed in clipping the wrong
fin. At the time the idea seemed preposterous that dwarf suckers
could change their spawning habitat so quickly.

Raney and Webster ('42) have contributed the following record
on the speed at which a common sucker migrated in Skaneateles Lake.
"One downstream sucker marked at the weir at noon on May 19, 1939,
was recaptured at 10 P. M. in a gill net set in the lake near the mouth
of the inlet a distance of about one-half mile".

SPAWNING HABITAT

The spawning habitat of dwarf suckers consisted of very shallow
riffles ; oftentimes where the water was scarcely deep enough to cover
their backs (Figs. 20 and 21). When this type of habitat was not

Fig. 21. Pools and riffles immediately al)ove the big pool illusiratcd in figure
19. Used extensiveh- b\- spawning dwarf suckers.

( 1131

Fig. 23. Inlet of Rich Lake. Dwarf suckers spawn in the riffles near the man
in the lower right. Common suckers, however, ascend to the deeper pools
near the spillway.

Fig. 24. Pools at the base of the spillway used by spawning common suckers
but not by dwarf suckers.

[114]

Life History, Ecology and Habits of the Dzvarf Sucker 115

available they utilized riffles with deeper and faster water. The writer
never has observed them in the act of spawning: in the deep pools where
the current was very slow, and they are not likely to use such places
except, possibly, on rare occasions when more desirable habitats are
not available.

Clean bottom of coarse sand or gravel are essential qualities of
the spawning habitat. Many of the small permanent inlets of Adiron-
dack lakes are of this general type, and consequently are potential
spawning habitats. Temporary inlets do not meet the requirements
and are avoided. Occasional small groups of breeding dwarf suckers
will accept the lowermost clean small riffles of the stream which, fre-
quently, are quite exposed. This may be due to crowded conditions
elsewhere, or difficulties in surmounting obstructions. In any event,
eggs deposited in such places are subject to greater losses from preda-
tors and shifting bottom materials, than those farther upstream. Most
migrating suckers do not stop until some major obstruction prevents
further progress. Generally dwarf suckers migrate less than one-
fourth mile, frequently not over one-eighth mile, after entering the
stream.

Cover, including both forest cover and that within the stream itself,
is a very important, if not essential adjunct of spawning habitats.
Dwarf suckers appear to avoid the unforested parts of the streams,
but this may be pure coincidence, however, because the more desirable
spawning sites generally are far enough inland to occur beyond the
flood plain, typical of Adirondack lakes. The forest cover, undoubt-
edly, gives some security from winged enemies, but it reduces the
intensity of light which, evidently, is more important. A reaction of
this nature is to be expected from a species of fish that is unaccustomed
to light most of the year.

Large boulders, overhanging banks, old logs, partially under-
mined trees or stumps, and various kinds of debris provide cover
within the stream itself. Dwarf suckers frequently avail themselves
of this cover and in so doing secure additional protection from light
and enemies. The pools provide another type of cover, more important
in many respects than those mentioned above. Dwarf suckers fre-
quently congregated in great schools in the deeper pools when not
actually engaged in spawning. That they have a greater feeling of
security in the pools is exemplified by their behavior. They generally
make a hasty retreat to the pools when disturbed, but their fears
quickly subside after reaching their objective.

Another attractive feature of pools is, of course, the absence of

116

Roosevelt Wildlife Bulletin

swift current, which makes it possible for the fish to rest with com-
parative ease. This is highly important because dwarf suckers utilize
a great amount of energj- from the time they enter the streams until
they leave. The energy expended in reaching the riffles is considerable,
but even more is utilized coincident with the spawning act. The fish
take advantage of the pools to recuperate after negotiating a difficult
obstruction during migration, or after an extended breeding session
on the riffles. Then too the pools provide shelter for those individuals
that are still unripe and consequently not ready to contact their mates
on the spawning sites. They, likewise, accommodate excess males,
of which there are many, as well as spent fish on the return journey
to the lake. The serviceability of pools is greatly improved if logs,
brush or other types of cover occur in connection therewith.

The preference for dark places and cover also was noted by
Greeley and Greene ('31, p. 84) at the Lower St. Regis Lakes in the
Adirondacks. They discovered that "the fish were spawning in a
culvert which conveyed the creek under a road and the darkness inside
this precluded detailed observation of the breeding behavior ... it
appeared that they avoided the sunny parts of the stream." Mather
('90, p. 164) states it "seeks shady woods" during the breeding season.

SPECIAL REACTIONS

Reaction to Inlet Waters. Dwarf suckers never have been
known to spawn in any but inlet streams, even when seemingly de-
sirable breeding habitats were available in outlet streams. This is
characteristic of other sucker species as well as most freshwater fishes
that habitually spawn in streams. The common shiners, Notropis
corniitus frontalis (Agassiz), of Wolf Lake, however, react in an
entirely diflferent manner. They always spawn in the outlet and have
never been known to select the inlet streams. The breeding season of
the shiners begin a few days before, but overlaps that of the dwarf
suckers.

\\'olf Lake outlet was dammed b\- beaver several years ago, about
a mile downstream. Tlie resulting pond contains several species of
fish, including dwarf suckers. The latter apparently migrated down-
stream as young, during highwater. A small group (perhaps two or
three hundred) of these dwarf suckers breed in Wolf Creek outlet,
which at this point changes its status to an inlet by virtue of an ex-
tensive beaver pond.

Reaction to Loss of Fins. Jordan ('05, p. 24) states that "the

Life History, Ecology and Habits of the f^warf SiicL-cr 117

paired fins are not in general used for progression in the water, but
serve rather to enable the fish to keep its equilibrium." Most writers
agree with Jordan in maintaining that the principal function of the
paired fins is to maintain equilibrium, but very few make any asser-
tions as to the absolute necessity of these appendages, in serving that
purpose. Hegner in his revised text-book on College Zoology (Heg-
ner, '26, p. 393) considers the paired fins so essential that the loss of
two or more would markedly disturb the equilibrium of the victim.
He claims that "if both pectoral fins are removed, the anterior end of
the fish sinks downward; if a pectoral or both pectoral and ventral
fins are removed from one side, the fish turns toward that side; and
if all four lateral fins are cut of¥, the fish turns completely over with
the ventral surface upward." Storer ("43, p. 576) infers that the loss
of fins disturbs the equilibrium, but only temporarily when no more
than two are removed. "Fishes deprived of one or two of the paired
fins soon learn to compensate for the loss of them." Hegner very likely
conducted experiments in the laboratory to determine the responses
of fishes to losses of various numbers and combination of fins. Evi-
dently his fish responded in a dif¥erent manner than would normally
occur in natural environments.

The dwarf suckers used in this study at no time exhibited any
unusual behavior as regards their equilibrium. In fact those minus
all five lower fins appeared to maintain their poise equally as well as
individuals having the full complement of fins. Since only one fin
was removed each year, except in cases where partial regeneration
occurred, it is possible that the fish learned to compensate for the
loss in each instance as mentioned by Storer (I.e.). Perhaps if more
than one, or all, of the lower fins had been removed at the same time
the effect would have been vastly diflferent.

It is believed that the loss of even five fins did not create a serious
handicap ; otherwise the number of returns would not have been so
great. Physically handicapped fishes, of course, are more vulnerable
to capture by predators, than normal individuals ; therefore it is be-
lieved that losses of marked fish would increase in direct proportion
to the number of removed fins. Actually this was the case, but there
was no means of determining whether or not the marked fish suffered
proportionately higher losses than unmarked fish. Perhaps the losses
of marked fish were entirely normal. The fact remains, however, that
36.3 percent of all the fish marked during the five-year study period
managed to obtain all the necessities of life and, in addition, return
on one or more occasions to participate in spawning activities. A con-

118

Roosevelt Wildlife Bulletin

siderable number accomplished this feat for five successive years, and
still appeared to be equally as healthy as unmarked individuals.

Breeding dwarf suckers did not appear to be disconcerted in the
least over the recent loss of fins or the cumulative efifect of past losses.
Those that were liberated downstream beyond the main assembly of
spawning fish after having been studied and marked soon obtained
their bearings and within a few hours had rejoined their companions.
The loss of fins from outward appearances neither discouraged the
suckers from completing the spawning nor prevented them from sur-
mounting the various obstructions and swift currents to reach their
objective.

Male dwarf suckers demonstrated that their fins are non-essential
in making contact with females during the sex act. In fact those with
several missing fins accomplished the act without any noticeable lack
of efficiency. Pearl organs formed on regenerated fins, but these were
fewer in number and usually much larger than normal. Secondary
sex characters on other parts of the fish were unaffected.

LIMNOLOGICAL RELATIONS

Temperature. Thermal stratification occurs in the lake and
is fairly distinct during July and August. The thermocline occurs at
a depth of 15 to 20 feet during most of July, but gradually descends
until it reaches the 25- to 30- foot level in August. During these months
there are ten to thirteen degrees difference in temperature between
the surface and the bottom in the deeper areas of the lake. The mini-
mum bottom temperature recorded during the summer of 1941 was
8.2° C at 11 :00 A. M. on July 2 and the surface temperature at that
time was 21.6° C.

The autumn overturn occurred during the second week in Novem-
ber in 1941 although the temperature had been quite uniform from
surface to bottom for about a month previously. The lake, normally,
is covered with ice from early December to early May — the spring
overturn taking place about May 1.

Dissolved Gases. The amount of available oxygen in the
deeper parts of W'olf Lake becomes very low except during the vernal
and autumnal overturn periods. Coincident with the loss of oxygen
there occurs a corresponding increase in the carbon dioxide content.
The oxygen and carbon dioxide determinations at Stations 4 and 5,
located in the two deep areas, are indicative of the entire lake. The
determinations were made on July 24 and July 31 and are computed
on the basis of cubic centimeters per liter of water.

Life History, Ecology and Habits of the Dwarf Sucker 119

Table 5. Oxygen and Carbon Dioxide Determinations at
Stations 4 and 5, Wolf Lake, July 24, 1941

Depth

(feet)

Free
Oxygen

Free
Carbon Dioxide

Fixed
Carbon Dioxide

Station
4

Station
5

Station
4

Station
5

Station
4

Station
5

Surface

5.56

5.59

.63

.83

1.92

1.82

5

5.97

6.08

.63

.83

1.90

1.90

10

5.96

5.83

.51

.89

2.05

1.80

15

5.76

5.69

.71

1.14

2.05

1.80

on

4.20

5.66

1.32

1.16

2.02

1.80

25

4.65

4.46

2,93

2.73

1.87

1.90

30

5.83

2.34

4.05

7.31

2.00

2.38

35

2.43

0.19

6.83

10.49

2.17

3.44

40

1.25

0.00

7.96

11.25

2.45

4.35

Gill nets and trammel nets placed near these stations, for the
most part, produced very poor or negative results, whereas those
placed in somewhat shallower water yielded both dwarf suckers and
brook trout in abundance. This also was demonstrated very well with
sets made perpendicular with the shore and reaching into deep water —
the bulk of the fish were captured between the littoral zone and the
25-foot contour. Since dwarf suckers are primarily bottom feeders
the absence, or near absence, of oxygen and the corresponding increase
in carbon dioxide at the lower levels would make such areas uninhabi-
table except for short periods at the turnovers.

Macroscopic Bottom Organisms. The macroscopic bottom
fauna of Wolf Lake was comparable to that of other unpolluted Adi-
rondack lakes — rather meagre. In the mucky areas tubificids and
chironomids were the most abundant forms numerically. Corethra
larvae and burrowing mayfly nymphs also were found in most of the
double samples taken with a 6" x 6" Ekman dredge. Many empty
tubes, mostly fragments, of tubificids and chironomids were found
amidst the muck.

Compared with the deep areas the littoral zone was markedly
more productive of bottom organisms, both quantitatively and quali-

120

Roosevelt irUdlifc I'lillctin

tatively, but these could not be considered abundant. Numerous small
caddis worms were found amidst sand while stonefly nymphs, mayfly
nymphs, amphipods, crayfish, small bivalves, snails, fish fly larvae and
other forms were taken in gra\el and l)eneath boulders, .sticks and
brush.

Other Features. Wolf Lake was slightly acid and the acidity
became more pronounced on the bottom of the deeper areas. The pH
of the upper 15 to 20 feet of water had a i)H of 6.4 at every station,
but the acidity gradually increased below that depth until it reached
a maximum of 5.7 at 40 feet.

Turbidity tests made in Wolf Lake throughout the sunnner
months show that light penetrated to an average depth of sixteen feet.
This ccjrresponds with the maximum de])th at which the littoral vege-
tation occurs. Likewise, the transition between sand or gravel bottom
and the vast area of muck bottom occurs at approximately this depth.

Roth jihytoplankton and zooplankton were fairly common
tliroughout the lake. Cyclof^s and Diaptomus were the principal cope-
pods ; Daphnia. Lcptodora. Bosiuina and Holopcd'uim the principal
cladocerans. Xoihalca and Anuraca were the most common rotifers,
but Polyarthra, Rattttlus and Triarthra were well represented.

CORRELATION OF TEMPERATURE AND SPAWNING

ACTIVITY

The spawning activities of dwarf suckers are influenced by
changes in the temperature of water in the spawning habitat. If the
changes are gradual, spawning is increased or decreased accordingly,
and no decided disturbance or upset is evident. Sudden changes, how-
ever, cause pronounced upsets in the spawning activities. The correla-
tions of atmospheric temperature, water temperature and the number
of dwarf suckers captured on the spawning beds in the North Inlet of
Wolf Lake during the 1941 spawning season are shown in graphical
form in Figure 25.

Abnormal increases in atmospheric temperature at the approach
of the spawning season usually cause a great influx of spawning
suckers from the lake. These ripen verj^ quickly, if they are not al-
ready ripe, and spawning is hastened to the extent that the season is
of shorter duration than nonnal. Abnormal decreases in atmospheric
temperature on the other hand may cause a decided curtailment in
spawning activities and a cessatioii of migration from the lake. If the
change is great, certain fish may not onl}- cease spawning but return

Fig. 25. Correlations of atmosplieric temperature, water temperature and num-
ber of dwarf suckers captured on spawning beds in North Inlet during the
1941 spawning season.

[121 ]

122

Roosevelt Wildlife Bulletin

to the lake until the temperature again becomes suitable. Temperature
decreases in the stream during the spawning season usually are more
sudden and therefore more devastating than temperature increases.
This, of course, is to be expected at such high altitudes immediately
following Winter, and particularly where the prevailing winds are
from the northwest with frequent changes to the north. A passing
cloud may precipitate an inch or more of cold water within a few-
hours. Such was the case early in the 1941 spawning season.

Dwarf suckers started their migration that season on May 15 dur-
ing tlie midst of a rather warm spell when the temperature of water
in the inlets had reached 51'' F. which was about normal. The streams
were well populated by May 17, and spawning was in progress. A se-
vere storm swept in from the north in the forenoon of this day, and
while it lasted only one and one-half hours, .86 inch of cold water had
been deposited. This was accompanied with, and followed by, strong
wind and lowered atmospheric temperature. As a matter of fact the
atmospheric temperature dropped more than 20 degrees within 48
hours. Naturally the volume of water in the inlet v,-as about doubled,
l)ut, more significantly, was reduced in temperature by five degrees.

\'ery few, if any, fish entered the stream on the night of May 17,
and many of those already in the streams descended to the lake.
The streams were practically deserted by May 19. The atmospheric
temperature began to rise on May 20, and by May 22 had reached a
maximum of 86 degrees F. — a gain of 25 degrees. The dwarf suckers
responded accordingly and again reached the peak of their spawning
activities such as prevailed five days previously.

On this occasion the water temperature increased very rapidly
with the result that spawning was hastened considerably. Another
sudden drop in atmospheric temperature accompanied by rain and hail
occurred during the night of May 23 and the following day. This
likewise caused the suckers to abandon the spawning streams. It so
happened that many, if not most, of the fish were through spawning
and this, perhaps, accounts for the fact that they failed to re-enter the
streams again that season.

When the atmospheric temperature remains fairly constant
throughout the breeding season the suckers reach the peak of their
upstream migration within a few days and gradually diminish in num-
bers thereafter. Usually the period of decline in numbers is prolonged
somewhat by virtue of the fact that young fish and especially females
do not ripen as soon as the others.

Raney and Webster ('42, p. 140) obsen-ed that common suckers

Life History, Ecology and Habits of the Dzvarf Sucker 123

migrating into the inlet of Skaneateles Lake showed a marked faUing
off in the numbers moving upstream when the water temperature de-
creased suddenly. While Stewart ('26, p. 150) mentions that the
spawning season may be retarded by subnormal temperatures, he made
no inferences with respect to sudden changes.

SEX RATIOS

The data on sex ratios were obtained from sexually mature fish
collected on the spawning beds of two inlets of Wolf Lake during six
successive years. Suckers collected at other seasons could not be sexed
quickly or with absolute certainty from external characters, therefore
the data on sex ratios for non-breeding fish are not included in this
discussion. The data on sex ratios of breeding dwarf suckers captured
in other waters of the Huntington Forest are likewise excluded, even
though a considerable number of records are available, because col-
lecting was accomplished at irregular intervals and was never extensive
anywhere.

The sex of each sucker included in the discussion on sex ratios
was determined positively. In most cases the sperm or ova flowed
freely, while the fish were being measured and marked. If this did
not occur voluntarily with ripe fish a sufficient amount of pressure
was applied to the abdomen to force a showing of the sex elements.
The enlarged abdomen of females, together with the various secondary
sex characters generally were sufficient to distinguish unripe males
from unripe females. Usually the sex of any fish could be determined
solely from secondary sex characters, but the dissemination of sperm
and ova conveniently served as a check on the determination. The
large anal fin of male suckers studded with robust i>earl organs was
particularly helpful in distinguishing males from females.

Each year during the first few days of the spawning run the
suckers were so plentiful that it was impossible to thoroughly seine
and secure data daily for all the suckers in the spawning streams ;
therefore representative sample catches were made over the entire
spawning area. This was particularly true during the early part of the
study while various techniques were being devised for expediting the
field work. After the data had been obtained on the advance group of
suckers, usually it was possible to handle subsequent migrants within
twenty-four hours after arrival. It can be assumed that, perhaps, a
considerable number of suckers spawned and returned to the lake dur-
ing the first few days of the season without being marked but that
practically none of the late spawners escaped.

124

Roosevelt Wildlife Bulletin

Table 6. Sex Ratios of Dwarf Suckers F"ound on the Spawning
Beds of the Tributary Streams of Wolf Lake, Hunting-
ton Forest

\ ear

Unmarked Fish

Unmarked and Marked Fish

No. of
Males

No. of
Females

Percent
Males

Percent
Females

No. of
Males

\o. of

Females

1 Percent
Males

Percent
Females

1 o^s

1,634

362

81.86

18.13

1,634

362

81.86

18.13

10^0

1,199

778

60.64

39.35

1,799

825

68.55

31.44

1940

1, 144

761

60.05

39.94

2,078

1,123

64.91

35.08

1941

2,726

493

84.68

15.13

3,596

662

84.45

15.54

1942

2,802

918

75.32

24.67

4,165

1,065

79.63

20.36

1943*

306

193

61.32

38.67

1,234

256

82.81

17.18

Totals. . . .

9,811

3,505

14,506

4,293

....

Percent of
totals. . .

73.68

26.32

77.16

22.83

* Entire poimhitinii on spawning beds of North Inlet for one day only.

The mo>t significant fact regarding sex ratios was that male
dwarf suckers ahvays greatly outnumbered the females on the spawn-
ing beds, not only from day to day, but throughout each spawning
season. Unfortunately there are no available data on sex ratios of
dwarf suckers other than those herewith presented so that compari-
sons cannot be made with specimens from other waters. In fact
very little exact data on sex ratios have been published even for the
common sucker, Catostomus coinuiersonmi comviersonnii (Lace-
pede). It would seem safe to assume, however, that the sex ratios
of the common sucker are comparable to those of the dwarf sucker
because their spawning habits are very similar.

Reighard ("20. p. 9) in describing the breeding habits of the
common sucker in Michigan says that "During the breeding season
males are at all times much more numerous on the rapids than fe-
males and during the greater part of the time none but males are
present. It does not follow that males are actually more numerous
than females. On the contrary data that I have collected at other
localities and at times when the fish were not breeding indicate that
*y>e, males and females are equally numerous. In the breeding season
the females do not mingle with the males on the rapids until ready

Life History, Ecoloyy and Habits oj the Dz<'arf Sucker 125

to lay their eggs. But from time to time a female comes from her
retreat in the deeper water above or below the rapid or from
beneath the bank and takes her place on the rapid. If no males
happen to be near she may lay quiet in one place for a considerable
time." Spoor ('38) found the sexes of the common sucker about
equal each year in Wisconsin.

The preponderance of male common suckers over females on
the spawning rapids as stated by Reighard (I.e.) for Michigan cor-
responds with the data on sex ratios of dwarf suckers on the spawn-
ing streams at the Huntington Forest. There was no indication,
however, of females living in seclusion above or below the rapids
until ready to join the males on the rapids for the spawning act. The
spawning streams used by the dwarf suckers possessed no inacces-
sible secluded places, and no fish of either sex was immune from
capture. The only possible way the females could have escaped
notice was by remaining in the lake until ready to spawn. This is
highly improbable because actually many females entered the stream
while they were in the unripe condition, particularly late in the
breeding season when young females were more in evidence than
those in the older age classes.

The number of marked and unmarked dwarf suckers of each
sex collected annually and their percentage relationships are shown
in Table 6. Several thousand spawning dwarf suckers collected at
\\'o\{ Lake over a period of si.x years, as indicated in this table,
should be sufficient to formulate definite conclusions on sex ratios.
Certainly they should indicate more than trends. While these fish
are from a single body of water they are quite indicative of the
situation in adjacent lakes on the Huntington Forest, as revealed
from sporadic collecting and casual observation throughout the dwarf
sucker spawning period for the past ten years. Likewise they coin-
cide with observations throughout the sunmier months on dwarfs
collected in Arbutus Lake in particular, but to a more limited extent
in other lakes.

The data in the table show that male dwarf suckers were alwa\ s
in excess of the females. In certain years there were approximatel}'
two males for every female, but during other years there were as
many as four or more males per female. Considering the number of
different individuals (13,316) sexed during the 6-year period, how-
ever, the radio was about 2.8:1. The difl:'erence becomes greater
(3.37:1) when the number from both sexes, represented by 18,799
fish, taken during the six years regardless of whether they had been

126

Roosevelt IVildlife Bulletin

sexed and marked in previous years, are used in making the compari-
sons.

The sex ratios of recovered fish likewise varied considerably and
there was some indication that a proportionately smaller number of
females than males failed to return to the spawning grounds while the
study was in progress. Possibly this may be considered mere coinci-
dence rather than an indication that females are shorter "lived or have
a proportionately higher mortality rate, especially since the recoveries
of suckers marked in 1939 represent a ratio of 2 : 1 in favor of males.

The following table (Table 7) shows the sex ratios of the 12,817
individual dwarf suckers, exclusive of all recoveries, marked during
the five-year study period. Also the sex ratios of recoveries in sub-
sequent years for each year group.

Table 7. Sex Ratios of Dwarf Suckers for Each of Five
Successive Years at Time of Original Capture axd Upon
Return in Subsequent Years

Year

Number Siexed
and Marked

Sex
Ratio

Recoveries

Sex
Ratio

Total

Males

Females

Total

Males

Females

1938

1,996

1,634

362

4.5 : 1

1,102

969

133

7.2:1

1939

1,977

1.199

778

1.5 : 1

952

644

308

2.0 : 1

1940

1,905

1,144

761

1.5 : 1

1,150

948

202

4.7 : 1

1941

3,219

2,726

493

5.5 : 1

1,097

1,000

97

10.0 : 1

1942

3,720

2,802

918

3.0 : 1

539

500*

39*

13.0 : 1

Totals. . .

12,817

9,505

3,312

2.8 : 1

4,840

4,061

779

5.2:1

* Number in North Inlet of Wolf Lake, June 1, 1943.

Life History, Ecology and Habits of the Dwarf Sucker 127

RETURNS FROM MARKED FISH

One of the most significant characteristics of dwarf suckers, as
revealed from the data on marked individuals, was the habit in most
cases of returning to the identical stream each year when actually there
was a choice between two suitable spawning streams. This habit was
demonstrated so well in the first two years of the study that during the
other years when it was no longer possible to differentiate all repre-
sentatives of the two inlets it was considered safe to assume that at
least 95 percent of the marked dwarf suckers taken in each inlet had
spawned in the same stream on previous occasions. This assumption
unquestionably was very conservative.

Table 8. Summary of Returns Based on First Return During
First Two Years After Marking

Year

Total
Number
Marked
First Time

Total
Number
Returns
First Time

Total
Percent
Returns
First Time

Percent
Returns
First Year
after Marking

Percent
First Returns
Second Year
after Marking

1938

1,996

830

41.08

32.41

5.76

1939

1,977

949

48.00

44.86

1.87

1940

1,905

626

32.86

30.86

1.83

1941

3,219

1,146

35 . 60

33.48

2.11

1942

3,720

539*

14.48

14.48

* From census of population in North Inlet on June 1.

Table 9. Summary of Returns of Marked Dwarf Suckers
Showing First Return and Repeats

Year

Total
Number
Marked
First Time

Total
First
Returns

Total
Second
Returns

Total
Third
Returns

Total
Fourth
Returns

Total
Fifth
Returns

1938. . . .

1,996

830

315

111

24

2

1939. . . .

1,977

949

290

61

8

1940. . . .

1,905

626

211

63

1941. . . .

3,219

1 , 146

247

1942. . . .

3,720

539*

128

Roosevelt Wildlife Bulletin

Of the 1996 dwarf suckers marked during the first season (1938).
647 or 32.4 percent were recovered a year later and all but eighteen of
these recoveries had returned to the same stream. Thirteen of these
eighteen had changed from the South Inlet to the North Inlet — from
the smaller and least populated to the larger and more densely popu-
lated stream. Xo females were included among those making this
change in spawning habitat.

Table 10. Summary of Marked and Unmarked Dwarf Suckers
Captured in the Inlets of Wolf Lake in 1939

Marked in North Inlet in 1938

Marked in .South Inlet in 1938

Stream in which
Recovered

Males

Females

Stream in which
Recovered

Males

Females

North Inlet

467

59

South Inlet

100

3

South Inlet

13

0

North Inlet

5

0

Total Recoveries. . .

480

59

Total Recoveries. .

105

3

Total unmarked. . . .

883

686

Total unmarked . . .

331

77

Grand Total

1,363

745

Grand Total

436

80

Table 11. Summary of Marked and Unmarked Dwarf Suckers
Captured in the Inlets of Wolf Lake in 1940

North Inlet *

South Inlet **

Year(s) Marked

Males

Females

Year(s) Marked

Males

Females

1938

33

45

1938

34

3

1939

438

279

1939

127

7

1938, 1939

233

18

1938, 1939

36

0

Total Recoveries. . .

704

342

Total Recoveries. .

197

10

Total unmarked. . . .

862

685

Total unmarked. . .

274

85

Grand Total

1,566

1,027

Grand Total

471

95

* Not included are 37 suckers originallv marked in South Inlet as follows: Two
in 1938, 27 in 1939, four others in 1938 changed to this inlet in 1939 and four
marked in 1938 and 1939 changed this year.

** Not included are fi\e suckers originally marked in North Inlet as follows:
three in 1938 and two in 1939. One male in the 1938 group returned in 1939
before changing and another changed in 1939.

Life History, Ecology and Habits of tlie Dwarf Sucker 129

In 1940 the returns, of course, included dwarf suckers marked
in 1938 and 1939; either one or both, but with the greatest number
in the latter season. Potentially there were 3,973 marked suckers in
Wolf Lake but only 1,296 or 32.6 percent of that number were re-
covered during the season. There were forty-two individuals among
the marked fish that had changed their spawning stream from that of
some previous season. Twenty-seven of these that were captured in
the North Inlet had been marked in the South Inlet during the pre-
ceding season and four others during the preceding two seasons. Four
fish marked in the South Inlet in 1938 had used the North Inlet in
both 1939 and 1940. Two others also marked in the South Inlet in
1938 were not taken in 1939 but appeared in 1940 in the other inlet.

Only five marked suckers were found in the South Inlet that had
been taken previously in the North Inlet. Two of these had spawned
in the North Inlet in 1938 and 1939. Another had used the North
fillet in 1938 but had come to the South Inlet in the next two seasons.
The other two were marked for the first time in 1939. One female was
found among those making the change in the spawning habitat. The
number of dwarf suckers shifting from one stream to the other, as

Table 12. Detailed Results of Marked and Unmarked Dwarf
Suckers Captured in the 1941 Season

North Inlet *

South Inlet **

Year(s) Marked

Males

Females

Year(s) Marked

Males

Females

1938

2

1

1938

5

1

1939

20

13

1939

5

2

1940

436

97

1940

53

2

1938, 1939

0

1

1938, 1939

1

0

1938, 1939, 1940. . . .

74

1

1938, 1939, 1940. . .

10

0

1938, 1940

7

2

1938, 1940

9

0

1939, 1940

9

0

1939, 1940

30

0

Total Recoveries . . .

727

156

Total Recoveries. .

113

5

Unmarked Fish ....

2,442

456

Unmarked F"ish . . .

301

44

Grand Total

3,169

612

Grand Total

414

49

* 13 males and one female originally marked in South Inlet in 1939 not included
** One female originally marked in North Inlet in 1938 not included.

130

Roosevelt Wildlife Bulletin

Table 13. Detailed Results of Marked and Unmarked Dwarf
Suckers Captured ln the 1942 Season

North Inlet

South Inlet

Recoveries
Year(s) Marked

Males

Females

Recoveries
Yearfs) Marked I Males

Females

1938

18

1

1938

18

1

1939

3

5

1939

1

0

1940

16

12

1940

10

1

1941 .

940

89

1941

46

4

1938, 1939, 1940. . . .

3

0

1938, 1939, 1940.. .

1

0

1938, 1939, 1940,

1 OA 1

A

y)

1938, 1939, 1940,
1941

1

A
U

1
1

U

1938, 1940

2

0

lo^fi lOAn 1011
lyoo, iy4u, iy4i. . . .

7

A

U

1938, 1940, 1941...

1

0

lO^fi 1011

e

U

1938, 1941

1

0

1939, 1940

4

3

1939, 1940

1

0

1939, 1940, 1941....

48

8

1939, 1940, 1941...

7

0

1939, 1941

3

1

1939, 1941

1

1

1940, 1941

180

19

1940, 1941

12

0

Total Recoveries . . .

1,251

138

Total Recoveries. .

102

7

Unmarked Fish. . . .

2,263

815

Unmarked Fish . . .

549

105

Grand Total

3,514

953

Grand Total

651 112

recorded above, represents slightly more than three percent of the
total recoveries of 1,296 for that year.

At the beginning of the 1941 season there were, potentially, 5,914
marked dwarf suckers in Wolf Lake, disregarding losses from all
causes. During that year 1,001, or nearly 17 percent of these were
recovered. In like manner at the beginning of the 1942 season there
were, potentially, 8,157 marked dwarf suckers in \\o\i Lake and dur-
ing that year 1,498, or slightly over 18 percent of these were recovered.

The marking was discontinued after the 1942 season, but a census
was made of the fish on the spawning beds on a single day for each
of the four following years to determine the size of the population and

Life History, Ecology and Habits of the Divarf Sucker 131

sex ratios as well as to obtain detailed data on returns of marked fish.
In 1943 and 1944 it was found that approximately two-thirds of the
suckers on the spawning beds were returns. To be more specific, in
1943, 991 or 66.5 percent of the 1.490 dwarf suckers taken on the
spawning beds of North Inlet were recoveries with representatives that
had been taken on each of the previous five years of the project. The
1944 census, which was made on a day prior to the peak of the spawn-
ing season, inckided 698 suckers from both inlets of which 352 or 50.4
percent were returns. Considering North Inlet alone, which had been
given greatest consideration in previous years, 269 or 62.8 percent of
the 428 spawning dwarf suckers were returns.

Table 14. Census of Marked and Unmarked Dwarf Suckers
IN the North Inlet of Wolf Lake, June 1, 1943

North Inlet

North Inlet

Recoveries
Year(s) Marked

Males

Females

Recoveries
Year(s) Marked

Males

Females

1938

4

0

1939, 1940, 1941. . .

3

1

1939

14

1

1939, 1940, 1941,
1942

8

0

1940

2

1

1939, 1940, 1942...

1

0

1941

60

8

1939, 1941

4

1

1942

500

39

1939, 1941, 1942. . .

2

0

1938, 1939, 1940...

0

1

1940, 1941

12

1

1938, 1939, 1940,
1941

1

0

1940, 1941, 1942...

62

1

1938, 1939, 1940,-
1941, 1942

2

0

1940, 1942

6

1

1941, 1942

240

7

1938, 1940, 1941,
1942

5

0

Total Recoveries. .

928

63

1938, 1941, 1942....

1

0

Unmarked Fish . . .

306

193

1938, 1942

1

1

Grand Total

1,234

256

On May 31, 1945 there were 991 dwarf suckers in North Inlet,
consisting of 780 males (78.7 percent) and 211 females (21.3 per-
cent). Three hundred and thirty-four (33.7 percent) of these were
recoveries of marked fish. The population on this day was rather low

132

Roosevelt Wildlife Bulletin

Table 15. Census of Marked and Unmarked Dwarf Suckers
IN THE Spawning Streams of Wolf Lake, May 24, 1944

North Inlet

South Inlet

Recoveries

1 Cell \p } IVldlKcU

iviaics

females

Recoveries
\ear(s) Marked

ivia.ics

Females

1938

2

0

1938.

1

1

1939

9

1

1939

7

1

1940

0

2

1940

1

0

1941

14.

104.1

i.

T.
J

1942

1 ■^o

\J

10J.7

4.R

0

10^8 104.7

1

1

n
u

10^8 1040 1Q41
1942

2

0

IQ^ft 10^0 lOdO
iv<)o, ivov, iy*u,

1942

1

0

1939, 1940, 1941....

1

0

1939, 1941

1

0

1939, 1940, 1941,
1942

1

1

n

u

1040 1041 1047
ly-rU, iV-rl, lV*i<i. . .

1

1

1940, 1941

3

0

1941, 1942

9

0

1940, 1941, 1942....

14

0

1940, 1942

2

0

1941, 1942

65

2

■ ■

Total Recoveries. . .

253

16

Total Recoveries. .

75

8

Unmarked Fish ....

120

39

Unmarked Fish . . .

145

8

Grand Total

373

55

Grand Total

220

50

and this was attributed to the sudden drop in temperature of the pre-
vious twenty-four hours.

The census in 1946 was taken on June 4 which, undoubtedly, was
near the end of the breeding season. However, 100 fish were caught
in South Inlet and 124 in North Inlet. Although only six of these
suckers (all males) were recoveries they were represented by one fish
marked in 1938, one marked in 1938 and 1939 and three marked in
1942. The two suckers in the lot that were marked during the first
year of the stud}- were at least twelve years of age, possibly older. They
were less than six inches in standard length.

Tables 8 to 16 give a rather detailed summary of the returns of

Life History, Ecology and Habits of the Dicarf Siieker 13i

marked fish. It will be noted that less than one-half of the marked
dwarf suckers in \\'olf Lake have been recovered and that the majority
of those returning did so the year after the original mark had been
inflicted. Although a sharp decline occurred on the second anniversary
of marking, still a considerable number returned twice in succession
and a very limited number appeared three or more years in succession.

Generally speaking, a proportionately greater number of marked
females than males failed to appear in subsequent years. The 1940
season, however, was an exception in the case of North Inlet as may
be noted in table 11. (342 of the 1,046 recoveries were females). The
females that did return after being marked, with very few exceptions,
used the same stream where originally taken.

One might speculate as to what has happened to those marked
individuals unaccounted for in recoveries. A considerable portion of
them undoubtedly should properly be credited to mortality from vari-
ous causes. Some are overlooked and others may spawn in the lake.

Table 16. Census of Marked and Unmarked Dwarf Suckers
IN THE North Inlet of Wolf Lake, May 31, 1945

North Inlet

North Inlet

Recoveries
Year(s) Marked

Males

Females

Recoveries
Year(s) Marked

Males

Females

1938

1

0

1940, 1942

2

0

1938, 1942

2

0

1941

16

0

1939

6

0

1941, 1942

53

5

1939, 1940, 1941. . . .

0

1

1942

202

29

1939, 1940, 1942....

1

0

1940

3

2

Total Recoveries. .

296

38

1940, 1941

2

1

Unmarked Fish . . .

484

173

1940, 1941, 1942....

8

0

Unmarked Fish . . .

780

211

134

Roosevell Wildlife Bulletin

FECUNDITY AND EARLY LIFE HISTORY

Egg Productivity. Dwarf sucker eggs are about the same
size as those of common suckers. Eggs removed from formalin-pre-
served females average about thirteen per lineal inch or a diameter
equivalent of .0769 inch (slightly less than 2 mm.) per egg. According
to vonBayer's table, this is the equivalent of about 150,000 eggs per
liquid quart. The number of eggs per female normally varies directly
with the individual and particularly with its length. Thus it was found
that a 4)4 -inch female produced, on the average, only 775 eggs, while
a 5-inch female had slightly less than 1.000 eggs, a 6-inch female about
1,300 and a 7-inch female 1,500 eggs. In selecting fish for the egg
counts the writer endeavored to take only those that showed no evi-
dence of having partially spawned. Some of the fish, however, may
have deposited a few eggs prior to capture in whicli event the condition
of the ovaries would not be noticeably affected.

Stewart ('26) did not count the eggs of common suckers within
the size range of the dwarf sucker. The smallest females from w-hich
he obtained data on egg-productivity included a 12-inch individual with
18,000 eggs and a 15-inch individual with 31,2(X3 eggs.

Referring to Table 3 it will be observed that the entire catch of fe-
male dwarf suckers averaged slightly less than six inches and accord-
ingly produced an average of about 1,300 eggs per fish. This means
tliat in 1940 and in 1942, when the maximum number of females were
found in the spawning inlet streams, the annual output of eggs was
nearly one and one-half million, but in the other years considerably
less. In all probability the output was somewhat greater because it
must be admitted that some of the females evaded capture, particularly
during the first season, while techniques were being developed for
handling large numbers.

Incubation. On May 24, 1942, which date was near the end
of the spawning season, about a quart of dwarf sucker eggs were
stripped and fertilized at the X^orth Inlet of Wolf Lake. After they
had become thoroughly hardened they were transported to Oneida,
N. Y., a distance of more than one hundred miles, and placed in jars
at a private hatcliery where the water supply registered 60° F. The
temperature increased quite rapidly thereafter, so that on May 28 and
29 it registered 70° F. A cold rain reduced the temperature to 66° F.
on May 30, and to 62° F. on June 1. Tlie eggs hatched on the last-
mentioned date, eight days hatching time. The fry were actively
swimming on June 4 witli the water temperature at 64° F. They were

Life History. Ecology and Habits of tlic Dzvarf Sucker 135

planted three days later in a private pond in water registering 74° V.
at planting site. The quart of eggs produced about 1,500 fry — the
heavy losses being attributed mainly to low fertility resulting from
inac^equate facilities at the collecting site.

These incubation records for dwarf sucker eggs agree very well
with those of Raney and Webster ('42) for common suckers in
Skaneateles Lake inlet. The incubation period was about a week in
each instance.

Development of Fry. It has been impossible thus far to dif-
ferentiate with certainty dwarf sucker fry from common sucker fry.
The former, apparently, abandon the spawning beds immediately after
hatching and thereafter spend the greater part of their existence in
deep water. Schools of sucker fry occasionally were observed in
shallow water and these may have been the young of either or both
subspecies, because so far as is known the young are quite similar in
appearance, and the characteristics used in distinguishing the adults
are not apparent at that stage of development.

Collections obtained at various times and circumstances in the
lakes of the Huntington Forest indicate that two distinct size classes
are represented, and this may be significant. These classes, however,
are not too clearly dif¥erentiated until a year's growth has been at-
tained. Four small suckers collected in shallow water at the south end
of Wolf Lake on June 3, 1933 obviously were yearlings as they were
only one and one-half inches in total length, and the date almost identi-
cal with the spawning season. Additional collections from this lake
on July 14 indicated that considerable growth had taken place — the
lengths then ranged from 2% to 3^ inches, total length. These sizes
compare favorably with young froin artificially fertilized eggs that
were reared one year in a hatchery pond followed by one year in an
aquarium.

In Catlin Lake and its tributaries, sucker fry obtained in shallow
water during July and August revealed that growth was much faster
than was the case in Wolf Lake. Fry of the current season taken on
July 25 were quite uniformly ^-1 inch in total length. Another col-
lection of 35 fry, taken on August 14 of the same year, ranged from
% to 1^ inches, with 1^^ inches as the average. Yearling suckers
taken in the inlet of Deer Lake ranged from 3^ inches to 4 inches.
It seems quite obvious that the sucker fry taken in Wolf Lake were
dwarfs, and that the others were mostlv, if not entirely, common
suckers. "W'hile the comparisons are not made with fry from the same
lake the habitats, nevertheless, were quite similar in many respects.

136

Roosevelt Wildlife Bulletin

Carbine ('43) reports that common sucker fry artificially hatched
and reared in ponds attain an average length of 3-4 inches at the end
of 186 days (November 17). Hubbs and Crcaser ('24), however,
state that those from Douglas Lake, Michigan, average only 72 mm.
(2% inches) the first year. The Douglas Lake records compare very
well with those of Oneida Lake (Adams and Hankinson, '28).

FOOD AND FOOD RELATIONS

Dwarf suckers like many other species of fish with inferior type
of mouth feed on bottom organisms. The bottom of Wolf Lake, in
the areas customarily inhabited by the suckers the greater part of the
year, consists of muck — very soft and oozy in texture and sufficiently
deep to completely cover all mineral soil. This type of bottom is
never particularly rich in macroscopic animal organisms, and Wolf
Lake. is no exception. Blood worms {Chironomus pluniosus) , phan-
tom midge larvae {Chaoboriis pitnctipennis) and tubificids are the
most frequent representatives of the bottom samples. Small clams
(Sphaerium sp.), mayfly nymphs, caddisflies, snails and small scuds*
occur in very limited numbers.

The stomach and intestinal contents of several dwarf suckers
collected in the lake during August have been analyzed, and it was
found that practically all the animal organisms discovered in the
bottom samples were represented. The suckers customarily had
utilized a preponderance of one organism to the near exclusion of
others. Thus one sucker had devoured 23 clams (Sphaeriimi sp.)
and four Chironomus. Others had fed almost exclusively on Chiro-
nomus. Mayfly nymphs were the principal items in several others,
and caddisflies were well represented in several. L'sually consider-
able muck and other extraneous materials were found amid the
strictly food items. Some of this material evidently represented tubes
or cases used by tlie bottom fauna.

Two dwarf sucker fry about two inches in length that were trans-
ferred from a rearing pond to an inside aquarium removed the green-
ish layer of scum which had accumulated on the sand and fine
gravel bottom over a period of several months in a surprisingly
short time. The bottom of this aquarium was always free of organic
matter thereafter. However, there was little evidence that feeding
had taken place on the glass sides of the aquarium.

Suckers, in general, feed on eggs of other fish whenever they
are available and occasionally they may even devour their own eggs.

* Hyalclhi aztcca (Saussure) identified bj- Leslie Hubricht.

Life History, Ecology and Habits of the Jhcarf Sucker 137

The digestive tract of those collected on the spawning beds was prac-
tically devoid of food and there was no evidence of fish eggs. Kendall
and Dence ('29) observed dwarf suckers foraging in association with
other species of fish on the spawning beds of red-sided suckers,
Catostoinus cafostoiiius nanomyzon Mather, and brook trout at
Cranberry Lake, but none of the limited numbers of dwarf suckers
captured under such circumstances contained fish eggs. Small brook
trout, on the other hand, taken at the same time, had considerable
quantities of sucker eggs in their stomachs, indicating that eggs were
available. Common suckers feed on practically the same organisms
as do the dwarf suckers in the lakes of the Huntington Forest. The
bulk of the food is aquatic insects with molluscs forming a consid-
erable portion.

Dwarf suckers are useful principally in the capacity of a forage
species for game fish. The extent to which they are utilized in that
respect is, of course, unknown, but it is believed to be considerable.
In considering the food and feeding habits of dwarf suckers the
question arises as to whether their value as a foraging fish is suffi-
ciently great to compensate for the food they utilize and which
otherwise might be available to game species. Competition for the
limited supply of food naturally must be very keen. The inferior
type of mouth of the sucker should be a great advantage in securing
bottom organisms. Fishes with terminal mouths on the other hand
might have the advantage with respect to the fauna above the bottom.
Bottom dwelling forms that escape the suckers and other enemies
are potential food for fish, when they emerge coincident witli tlie
act of metamorphosis.

AGE DETERMINATIONS

An attempt has been made to determine the ages of dwarf
suckers by studying the growth rings on scales. Some of the scales
for these determinations were obtained from live spawning fish,
others from preserved fish obtained each year during the course of
the study. The annuli of dwarf sucker scales are much more difficult
to identify than those of the common sucker. While the scales are
relatively small this causes no particular inconvenience — it simply
necessitates proper magnification. Magnification, however, failed to
reveal any marked crowding of the circuli ; consequently it was neces-
sary to place greatest reliance on the irregularities in the structure
and the course of the circuli. In some instances the annuli were so
poorly defined that their number could not be ascertained positively

138

Roosevelt Wildlife Bulletin

Beckman ('43) made a thorough investigation of the literature
pertinent to the annulus formation on scales of fish, and published
tlic results of his findings on the annulus formation on scales of
certain game species, all with ctenoid type. In summarizing his data
the author considers temperature to be the "primary factor in an-
nulus formation" with food rated as of secondary importance.
Spawning had ver_\ little, if any, effect on the time of annulus for-
mation. His review of the literature reveals that in making age
determination of fish by the scale method too much reliance has been
placed on assumption rather than on exact knowledge. This accounts
for the diversified and, oftentimes, conflicting opinions on the subject.
Beckman (I.e., 285) intimates his uncertainty with respect to the
scale method by the statement that "the general validity of this
method has been assumed." Furthermore he adds that "The assump-
tion that the annulus is a j-ear mark and that but one annulus forms
each year has been and still is under criticism." The statement
(I.e., p. 285) that "the annnli on the scales do provide a clue to the
fish's age and growth has been demonstrated for many species and is
now confirmed for the material used in the present study" is. in the
writer's opinion, particularly applicable to dwarf suckers and un-
questionably to many other species, as well.

Blair ('38) found that the ages of landlocked salmon, from
waters of Xew Brunswick, in aliout 67 percent of the cases could
not be determined correctly from the scales. He says (p. 520) that
the fish were ".\n\where from one to four years older than is
recorded on tlie scales. This is due to the fact that the mature tish,
spawning consecutively for a number of years, grow very little from
one year to the next, consequently the scales show little, if any,
growth, and this coupled with extensive scale absorption, renders
the scales difficult, or impossible to be interpreted correctly."

There are records for a few dwarf suckers that have been on
the spawning beds annually for as many as six consecutive years.
Two of these have been preserved as museum specimens for future
study and reference. Both were males, 5^ and 6^4 inches, respec-
tively, in standard length. Two additional specimens, each 6|4
inches long, that had spawned on five consecutive seasons were also
preserved. While it is not known how old these fish were at the
time of the initial marking or how many times they had spawned
previously, it is certain that the first-mentioned group were, at least,
eight or possibly nine, years of age — probably older. Careful study
of scales from these specimens under varying degrees of magnitica-

Life History. Ecoloyy and Hahiis of llw Pi^vrf Sitckcr 139

tion and light intensity revealed that the number of so-called annuli
were not indicative of their true age. On the contrary the annuli
appeared to be more indicative of the number of years subsequent
to sexual maturity.

The scales of a 5^-inch male taken on June 1, 1943 showed
only six annuli. Previously it had been captured on five consecutive
years and thus was on its sixth known spawning trip to the North
Inlet of Wolf Lake. Assuming that it may have been on its first
spawning migration when originally captured in 1938, this fish
should have been at least nine years of age. Another male, 6^4
inches long, also on its sixth consecutive spawning trip, taken on the
same date, had eight annuli.

Two male dwarf suckers 5-^4 ^^ncl 6 inches in standard lenglh
captured on May 24, 1944 had been marked originally in 1938, but
had been recovered and subjected to additional marks three other
seasons. Wliile each of these fish had spawned at least seven times
their scales had only seven annuli.

Data on preserved specimens that are known to have spawned
more than once include two 6^ -inch males with seven annuli each,
two 6-)4-inch males and another 6}^ inches, all with six annuli that
had spawned at least five times; four males 5^4, 5-)4, 6 and 7 inches
in length with six annuli each that had spawned at least four times ;
three males 5^, 5^ and 6^ inches in length with 6, 5 and 6 annuli
respectively, had spawned at least three times ; three males 6, 6 and
6y2 inches in length with five annuli each had spawned at least five
times; six males 5, 5, 5%, 5^, and 6 inches in length with five annuli
each, one male 534 inches in length with four annuli. one male 5-j4
inches in length with six annuli, and one female 5^4 inches in length
with five annuli had spawned at least twice. It has been assumed in
certain instances of the above discussion that the dwarf suckers
spawned annually after reaching sexual maturity as they undoubtedly
do. The fact that certain individuals were not recorded each year
after the initial marking may indicate that they escaped capture.

At the conclusion of the field studies on spawning dwarf suckers
in May, 1941, scales for age determination were obtained from fifty-
three fish including some individuals that had been marked two and
three years previously — just completing their third and fourth known
spawning season. Those captured on four successive years consisted
of two males. 4^ and 5% inches in length, that had only four annuli
each ; three males 5. 5^4 and 6 inches in length that liad five annuli
each ; and one 6-inch male with six annuli. Ten fish in this group

140

Roosevelt Wildlife Bulletin

that had experienced three known spawning periods had annuli as
follows: one five-inch male, four; males 5, 5, Syi, 5^, 5}i and 6
inches in length five each ; males 5^, 5^ and 6 inches in length, six
each. The other suckers in this series, marked for the first or second
time, possessed a varying number of annuli (three to six).

In comparing the number of annuli with the standard lengths
of about two hundred individuals of assorted sizes, chosen at random,
it was found that there was a definite and consistent correlation in
the smaller-size groups, i.e., the four-inch and four and one-quarter-
inch classes. Beginning with the four and one-half-inch size, each
succeeding size class became more varied with respect to the number
of annuli. This, however, was expected because the majority of the
fish used in the age determinations were males which generally range
between five and six inches in standard length — average slightly less
than five and one-half inches. In other words most male dwarf
suckers acquire about two additional inches after reaching sexual
maturity. The amount and rate of increment after becoming adults
naturally varies with the quality and quantity of food, general health,
number and species of parasites and other factors. Some individuals
evidently cease growing at an early age, while others may perhaps
by virtue of a better environment, continue to put on increment even
beyond that of the average-size for the species.

Dwarf suckers as small as 3j/2 to 4 inches in standard length
occurred in consideral)le numbers on the spawning areas. Unfor-
tunately scales for only four of this size were available for age de-
termination. Each of these had three annuli. An occasional sucker
in tlie other size groups, likewise, possessed only three annuli and
these became ])rogressively scarcer with each increase in size group.

Most of the 4^4 -inch suckers as well as the 4^^-, 4^- and 5-inch
individuals had four annuli. Furthermore about one-third of the
suckers in the 5^-inch group, one-half of the 5^- and 6-inch groups
had five annuli. None of the fish had more than seven annuli — few
as many as seven. The smallest fish possessing seven annuli was
5y2 inches long. There were more representatives, however, in the
larger size groups.

The maximum age attained dwarf suckers cannot be posi-
tivelv determined on the basis of the maximum number of annuli
Ijecause. as mentioned elsewhere in the report, these structures are
not formed each year — possibly not at all or infrequently in the
juvenile stage. It would seem reasonably i^afe to assume that the
normal maximum span of life is at least twelve years. Two male

Life History, Ecology and Habits of the Dzi.'arj Sucker 141

suckers marked in 1938 on the spawning beds were recovered eight
years later — also on spawning beds. These were at least twelve years
of age.

Although considerable work has been done on age determination
of common suckers, Spoor ('38) apparently is the only author that
has presented data relative to the life span for that species. He in-
cludes data for "age-groups" as far as eleven years. The frequencies
for fish in that age-group were very low, as were those for age-group
ten. Stewart ('26), Spoor ('38), and Raney and Webster ('42) have
made intensive studies on age determinations of common suckers,
considering the number of annuli on the scales comparable to the
true ages. Evidently none of these authors had adults of known age
for comparison to check on their determinations. This is generally
considered not only useful but highly essential before judging correct
ages. The writer was fortunate in having at his disposal a consider-
able number of sets of dwarf sucker scales from spawning fish that
had been marked annually from one to five times. The fish from
which these scales were taken therefore were known to have been
sexually mature for, at least, as many years comparable to the num-
ber of times captured and marked. This, admittedly, is only a step
in advance of what has taken place previously, but invaluable, at
least as concerns dwarf suckers, in proving that the number of annuli
does not represent the true age.

It is quite evident that oftentimes age determinations are made
by interpolation or by guessing rather than by positive methods be-
cause the circuli may give no clue to the presence of certain annuli.
This weakness is universally recognized. Thus Raney and Webster
('42, pp. 145-146) mention that "No experimental work was carried
out to check the validity of the criterion used in determining the
age. Consequently the ages assigned to the various specimens are
reliable only if it is assumed that standards involved in judging the
age of better known species are equally applicable here." "The posi-
tion of the first annulus was usually difficult to determine. It was
located relatively close to the focus of the scale and was usually
poorly defined. Scales of yearling specimens from the lake showed
similar indefinite characteristics in the first annulus. Occasionally
the occurrence of several marks near the scale margin which could
not always be interpreted as annuli made an age assignment unre-
liable or impossible."

Spoor ('38) likewise expressed some doubt regarding the valid-
ity of his age determination of common suckers. He says (p. 463)

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Roosevelt Wildlife Bulletin

tliat "The annulus of the common sucker, then, appears to be marked
by a crowding of the circuli and cutting over of these crowded circuli
at or near the point where they enter the posterior quadrant of the
scale."

The lack of crowding of circuli at the annuli on the scales of
Wolf Lake dwarf suckers may be attributed to the prevailing low
temperatures throughout the year and the general feeding habits. It
is definitely known that dwarf suckers are partial to deep cold water
and that they do not cease feeding during the Winter. The more or
less evenly cold temperature that prevails from season to season evi-
dently has a regulative effect.

Stewart ('26, p. 172) observed that common suckers "Seined in
Xoveml)er from a large spring showed virtually no seasonal varia-
tions of the sort described as usually present [\'ariations in spacing
of circuli.] Though sexually mature (6 to 10 inches) not even the
markings were noticeable. This fact, taken alone, would point to the
direct regulative effect of an evenly cold temperature. Again the
greatest contrasts in spacing have been observed in fish from pools
between falls, where they probably have remained all their lives sub-
ject to extremes of warm and cold water."

ECONOMIC AND SOCIAL RELATIONS

In addition to dwarf suckers, eleven other species of fish are
known lo occur in Wolf Lake — all of which are strictly native to the
Adirondacks. Only two of these are game species — brook trout,
Sah'eliiiiis foiitiiialis foiitinalis (Mitchill). and lake trout, Cristivoiiier
iwDiayciish )iai)ioyciish (Walbaum). Netting operations indicated
that brook trout were fairly abundant, but the lake trout quite un-
common. Most of the larger brook trout (those above the 8-inch
class) were very slim so that tlieir weights were ratlier light com-
pared with their lengths. The largest specimen captured in the nets,
for example, was 17 inches in total length, but weighed less than
two pounds. The lake trout, on the other hand, that have been ob-
served in Wolf Lake are very large and in extremely good flesh.
The largest individual observed measured 35 inches total length and
weighed twenty pounds. It's scales showed eight annuli.

Brook trout appear to be suffering from the effects of over-
population : the result of natiu'al undistiu-bed processes over a long
period. The lake has not been stocked in many years, if ever, and
it has been closed to fishermen in recent vears. While the supply of
forage fishes is entire!}- adequate to support a much greater popula-

Life Historx, Ecology and Habits of the Di^wf Sucker 143

tion of brook trout the invertebrate life in the lake is not sufficiently
substantial to jjrovide a diversified diet of the type necessary for
maximum growth and development.

Small dwarf suckers undoul)tedly provide food for I)oth species
of trout and they should be more valuable for this purpose than
most of the other species of forage fishes because the trout and dwarf
suckers have a common habitat. It is definitely known that only a
small portion of the dwarf sucker fry reach maturity, and since brook
trout and lake trout normally include many small fish in their diet
it seems logical to conclude that these predatory fishes are. at least,
partlv responsil)le in maintaining normal dwarf sucker populations.

The other species of fish inhabiting the lake have no particular
economic importance. The red-bellied sunfish, Lepomis aiiritits (Lin-
naeus), while fairly abundant is too small to l)e an attractive panfish.
The common bullhead, Ameiurus ncbulosiis iiebiilosiis (Le Sueur),
is so rare (only one specimen has ever been recorded for the lake)
that its importance is inconsequential. Common suckers are well
represented and are a potential, though not commonly used food re-
source. Numerically the most abundant fish in the lake appears to
be the common shiner, A^otropis coniiitiis frontalis (Agassiz). Great
schools of this species frequently inhabit shallow water throughout
the Summer and are conspicuous because many of them are heavily
infested with Ligiila i)itesti>ialis. Red-bellied dace, Chrosonnis eos
Cope: horned dace, Scmotilus atrouiaciilatus atroiitaciilatiis (Mit-
chill) ; and cut-lips, Exoglossum maxillingna (Le Sueur), are very
common. Black-nosed dace, Rhinichthys atratuliis atratiiliis (Her-
mann), and northern sculpin. Coitus cognatus (Richardson), occur in
limited numbers in the lake immediately adjacent to the inlet streams.
The sculpins encroach on the dwarf sucker spawning grounds and
take a few eggs.

The population of fish species inhabiting shallow water of the
lake proper, regularly or periodically, is controlled to a considerable
extent by predatory birds and mammals. These animals, however,
may not affect the dwarf sucker population very seriously, either be-
cause of their limited numbers or by virtue of their particular feeding
habits.

The most likely avian predator would be the common loon be-
cause it frequents all parts of the lake, and is an extremely fast
swimmer below the surface. At least one family of loons (two adults
and one or two young of the season) habitually frequent Wolf Lake
each Summer. Sometimes these family groups are host to visitors

144

Roosevelt Wildlife Bulletin

from nearby waters as was the case on August 8, 1941 when seven
adults were observed in a group and engaged in various antics such
as swimming with outstretched wings, loud calling, sudden dashes or
diving, performed mostly in unison.

American mergansers and great blue herons frequent the shallow
areas and undoubtedly capture many fish during a season, but so far
as is known common shiners, sunfish and horned dace are the prin-
cipal victims. It is conceivable that young dwarf suckers might on
occasion wander into shallow water along with young common
suckers and thus become prey for the above-mentioned predators.
The young of the two subspecies of suckers, however, never have
been positively differentiated, consequently if young suckers were
taken it would be difficult to determine if dwarfs were included.

A few pair of herring gulls nest on the large boulders in Wolf
Lake each year ; the greatest number for a single season being five
pair. As in the case of loons, individuals from neighboring areas
occasionally visited the Wolf Lake group. Dwarf suckers apparently
are not an important item in their diet since the abundant excreta
deposited on the nesting boulders contained mostly ctenoid rather
than the cycloid type of scales possessed by dwarf suckers.

As many as five otters have been observed in the family group
at Wolf Lake. The group usually foraged along the east shore;
sometimes getting out into the dwarf sucker inhabited areas. The
excreta found near their favorite slide during the summer of 1940,
however, consisted mostly of crayfish fragments.

From the above discussion it would seem that the avian and
mammalian enemies of dwarf suckers on Wolf Lake proper are
rather insignificant. Brook trout, lake trout and common loon are
potential enemies because they are known to frequent the dwarf
sucker habitats. A considerable mortality occurs, as may be expected,
while the fish are in in the streams during the spawning season.
Concentrations of fish, or any other forage animal, are always in-
viting to predators, particularly when circumstances, such as ex-
hibited by the suckers, make it possible to obtain abundant food
with the minimum amount of effort.

Predators never were observed in the act of catching suckers,
although special trips were made to the streams at night for that
purpose. Attempts to catch them in steel traps likewise failed. It
would seem that only one predatory species was guilty of the offense
because the unutilized killed fish bore the same type of tooth- and
claw-marks, and further indicated that the predator had a decided

Life History, Ecology a)id Habits of the Di^'arf Sucker 145

preference for the head portion — the balance of the fish frequently
remaining undamaged. Some of the dead fish were untouched save
for deep flesh wounds. Perhaps some of these gashed fish had
escaped the attack, but died as a result of the wound. This is borne
out by the fact that an occasional live sucker was found in the
streams with such wounds.

The mammalian predators that are known to occur in the gen-
eral vicinity are : racccoons, red foxes, black bears, fishers, otters
and mink. American mergansers, common loons, herring gulls and
great blue herons occur in the lake and have been observed near or
at the mouth of each stream. It is conceivable that many fish are
completely devoured, in which case there would be no means of even
hazarding a reasonable guess as to the probable losses. The greatest
losses occur early in the season before the field work gets underway.
The writer suspects that otter ascend the inlets during the night and
are responsible for most of the losses. Foot prints observed in coarse
sand along shore, while rather indistinct, certainly look much like
those made by otter. There is, also, the possibility that certain other
predators may leave no evidence of their activities — they may carry
their prey to some remote area before proceeding with the meal or
making a cache.

A rather unusual condition was found with respect to a live and
very active dwarf sucker 138 mm., in standard length, collected in
the North Inlet of Wolf Lake on June 27, 1944. Part of the skull,
involving an area 9 mm. by 9 mm. and inward to the brain, recently
had been removed from that part located between the nostrils and
the eyes. Examination in the laboratory under magnification revealed
that both olfactory nerves and one olfactory bulb had been taken as
well as about one-half each of the other olfactory bulb and the
cerebral hemispheres. The concise manner in which the various parts
were severed indicates that this injury undoubtedly was caused by
some predatory bird, possibly a herring gull, since about a dozen
adults of that species were nesting in Wolf Lake at that time. While
the victim .showed no visible effects from the injury when captured,
undoubtedly it would have died in a few days. This was the only
dwarf sucker in the spawning stream on this date and furthermore
the only occasion when dwarf suckers occupied the area after the
regular spav/ning season.

Dwarf sucker eggs were surprisingly well concealed in the sand
and gravel of the spawning beds so that scarcely any were exposed
and thus subject to loss by spawn-eating fishes. At least a part of

146

Roosevelt Wildlife Hullelin

the uncovered eggs are consumed by the associated northern sculpin,
Coitus cognatiis Richardson, and brook trout, Salvelimis fontinalis
fontifialis (Mitchill). Neither species lived strictly on sucker eggs,
but varied their diet with insects, including Simuliuin pupae and
adults. One four-inch brook trout taken in South Inlet May 24,
1944 had fed almost exclusively on sucker eggs, and to the extent
that its belly was greatly distended.

The trout breed in the dwarf sucker streams during the autumn,
the eggs hatch in late winter or early spring, and the young reach
the stage at which the\- begin to take natural food when sucker
eggs become available. The fry increase in abundance as the season
progresses, and und()ul)tedly there are man\- more than are actually
observed because their markings, coupled with the fact that thev
adhere very closely to the bottom, make them rather obscure.

One sculpin collected on the spawning beds of the South Inlet
contained thirty-six sucker eggs in addition to a mayfly nymph.
Others had taken a few but the bulk of their stomach contents con-
sisted of a variety of insect larvae and adults. More than a hundred
eggs were taken from a four-inch brook trout. Yellow perch do not
occur in Wolf Lake and seldom enter the dwarf sucker spawning
beds of other streams. A school of about 50 individuals averaging two
to three inches in length, however, were observed on one occasion
in the spawning stream of Arbutus Lake. The lone individual that
was captured from the group had been eating sucker eggs. It is to
be presumed that the others were guilty of the same offense.

Horned dace, Seiiiotiliis atroinacitlafus atroiiiaculatits (Mitchill),
also spawn in the inlet streams of Wolf Lake, particularly the North
Inlet. Their arrival on the spawning areas was closely correlated
with the temperature of the water in the streams. They never ap-
peared until the dwarf suckers had reached the peak of their spawn-
ing activities and were beginning the return journey to the lake. The
dace maximum population occurred at the termination of the sucker
spawning season.

The horned dace constructed their nests well downstream mostly
below the spawning areas of the dwarf sucker. Although there was a
slight overlapping of spawning grounds the two species seemed to
carry on their particular activities without conflicts or interference
of any kind. When the breeding season is over the dace may avail
themselves of the supply of sucker eggs and newly hatched fry. The
latter should be especially attractive ; coming at a time when the
dace are about to resume normal feeding habits.

Life History, Ecology and Habits of the Dwarf Sucker 147

PARASITES

Thf following;- data on host-parasite relationships were obtained
in conjunction with, and coincidental to, other studies on breeding
dwarf suckers. They seem to have sufficient importance to warrant
inclusion in this report and may be contributions to the knowledge
on the lite histories of the parasites involved. It should be stated at
the outset that, in general, dwarf suckers appear to be experiencing
a relatively healthy existence in the lakes on the Forest. The very
fact that so many individuals were capable of successfully completing
the spawning functions for several years in succession, despite the
possible handicap from the loss of one or more fins is quite indica-
tive.

In the 1938 spawning season several dwarf suckers were found
at Wolf Lake that were harboring PMlometra nodulosa Thomas in
the connective tissues of the cheeks and lips, particularly the cheeks.
Several of the hosts carrying this nematode were preserved for
future study. Strange as it may appear, scarcely any evidence of
further infestation from this worm was observed at Wolf Lake in
subsequent years, although each fish was examined superficially
in that respect.

While studying a collection of common suckers obtained June
2, 1943 from the spawning grounds in a tributary of Arbutus Lake,
the writer was surprised to find a rather high incidence of infection
of Ph'ilometra in the connective tissues of the pectoral fins. Five of
the twenty-one suckers in the collection were infected and two or
more worms were found on each fish, either on one or both pectorals.
The same condition likewise prevailed in subsequent years. These
Philometra have not been identified to species. They appear to be
different from P. nodulosa. The worms usually occupied the upper
thicker portion of the fins utilizing the tissues between two or more
adjacent fin rays. Whenever the space between a pair of fin rays
became inadequate for the worm it made an abrupt crossing to the
adjacent space and thence moved in a diametrically opposite direction.

The cheeks and lips of every dwarf sucker in the Arbutus
Lake collection were carefully studied, but there was no evidence of
infestation eitlier in the lips or pectoral fins. Possibly this may be
the first record of its appearance in the pectoral fins of any species
of sucker, because the writer was unable to find any published ac-
count of its occurrence other than in the cheeks and lips. One of
the worms was dissected, and its uterus was observed to be well
filled with developed larvae.

148

Rooscvcll Wildlife IhiUctin

During tlio 1940 dwarf sucker spawning season a good nianv
cestcKles of the family caryophyllaeidae {Glaridacris catostomi cop-
per) were found in the bottom sediment of the retaining pails after
batches of fish had been confined for a considerable time (about one-
half hour on the average). Practically every batch of fifty or a
liundred yielded a dozen or so cestodes in this manner. This phe-
nomenon never was observed during other years under similar cir-
cumstances, and the application of the same techniques. The worms
were not eliminated while the fish were struggling in the hands of
the writer during tlie period they were being subjected to various
treatments including the amputation of fins. Possibly reduction of
the oxygen supply to near exhaustion as the result of retaining the
fish in such limited confines may have been a contributory factor in
causing this to occur. Sometimes the fish were retained until they
began gulping air from the surface or became prostrate. While this
treatment never was fatal to the host it may have stimulated the
parasites to leave the intestinal tract. The appearance of this cestode
in this manner during a single session suggests that it may have been
scarce at other times. The preserved worms average about 25 mm. in
length.

Ligula intcstinalis Linnaeus occurs in great numbers in the
common shiners, Notropis cornutus frontalis (Agassiz), of Wolf
Lake, but the dwarf suckers for some reason support few of these
worms, which seems contrary to what might be expected— usually
members of the sucker group are quite vulernable to attacks by
ligulas.

Diphyllobothriidae of the genus Schist occphalxis also occur in
Wolf Lake, but they have been observed only in the sculpin, Cottus
cogiiatiis Richardson, captured on the dwarf sucker spawning riffles.

Some of the dwarf suckers collected in Wolf Lake during July,
1941 were heavily infested with Acanthocephala, Pomphorhynchus
hulbocolli Linkins. Most members of the sucker family are highly
susceptible to this parasite ; therefore its presence in dwarf suckers
is in no sense unusual.

Five leeches, Placobdella parasitica (Say)*, were found attached
to the inside of the gill cover of three landlocked dwarf suckers
captured in Arbutus Lake inlet on July 4, 1944. A considerable
number of other leeches, Macrobdella decora (Say)*, occurred in
the same habitat, but these did not molest the dwarf suckers, seem-
ingly preferring black-nosed dace in the association instead.

* Identified by Dr. Raymond Myers, Colgate University, Hamilton, N. Y.

Lite History, Ecology and Habits of the Dtvarf Sucker 149

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