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22001199 SOUTHEASTERN NATURALIST 1V8o(3l.) :1387,3 N–3o8. 03
Behavior of Chrosomus saylori (Laurel Dace) During the
Breeding Season
Christopher T. Cronnon1,2, Meredith Harris3, Bernard Kuhajda3, and Hope Klug1,2,4,*
Abstract - Chrosomus saylori (Laurel Dace) is an endangered fish species that exclusively
inhabits 2 creeks in Rhea County, TN: Bumbee Creek and Youngs Creek. To the best of our
knowledge, the behaviors that Laurel Dace exhibit both during and outside of the breeding
season have not been previously documented. In this study, we recorded, analyzed,
and documented behaviors that are exhibited by captive Laurel Dace during the breeding
season. The behaviors that the Laurel Dace exhibited were chasing, attacking, a sigmoid
display, chafing, territoriality, following behind, shoaling, biting of the cloaca, and a dance.
We discuss the occurrence of these behaviors in relation to reproduction and the behaviors
of relatives of the Laurel Dace.
Introduction
Chrosomus saylori (Skelton) (Laurel Dace) is an endangered minnow that is endemic
to Tennessee. The Laurel Dace is currently thought to inhabit only 2 creeks in
Rhea County, TN: Bumbee Creek and Youngs Creek. Several aspects of the Laurel
Dace’s diet (George et al. 2016, Skelton 2001), habitat (George et al. 2016), life
history (George et al. 2016, Skelton 2001), morphology (Skelton 2001), and population
genetics (George et al. 2016) have previously been described. However, little
is known about the behavior of Laurel Dace. Indeed, to the best of our knowledge,
no previous studies have formally documented the behavior of the Laurel Dace during
or outside of the breeding season. Understanding the behavior of this species is
important from a natural history perspective and to help facilitate captive breeding
and re-introduction programs.
We describe the Laurel Dace behaviors we observed during a portion of the
natural breeding season. Specifically, we focused on documenting behaviors
that were likely to be associated with reproduction. We filmed the behavior of
a captive group of Laurel Dace and noted any potential reproductive behaviors,
including courtship behaviors and behaviors that occurred after egg fertilization.
We then developed an ethogram of observed behaviors and quantified the relative
frequency of each.
1Department of Biology, Geology, and Environmental Science, University of Tennessee at
Chattanooga, Chatanooga, TN 37403. 2Honors College, University of Tennessee at Chattanooga,
Chattanooga, Chatanooga, TN 37403. 3Tennessee Aquarium Conservation Institute,
Chatanooga, TN 37405. 4SimCenter, University of Tennessee at Chattanooga, Chattanooga,
Chatanooga, TN 37403. *Corresponding author - Hope-Klug@utc.edu.
Manuscript Editor: Nathan Franssen
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Materials and Methods
Fish collection
On 22 November 2016, staff from the Tennessee Aquarium Conservation Institute
(TNACI) collected 6 Laurel Dace juveniles from Bumbee Creek (Rhea
County, TN) and held them at the facility. On 10 April 2018, another 20 adult
Laurel Dace were caught and relocated to TNACI using 3.05 m x 1.83 m seines in
Bumbee Creek. One fish died prior to the start of the present study. Laurel Dace
were collected under Scientific Collection Permit number 1308 from the Tennessee
Wildlife Resource Agency, Endangered and Threatened Wildlife Permit number
TE22311A-4 from the US Fish and Wildlife Service, and IACUC Approval Number
17-01 from the Tennessee Aquarium and Tennessee Aquarium Conservation Institute
Animal Health and Welfare Committee. We were unable to quantify the number
of males and females obtained because the sex of individual Laurel Dace cannot
be externally identified with complete confidence. Coloration can vary daily, and
males and females appear relatively similar.
Housing
During the present study (April–June 2018), we housed 25 Laurel Dace in a
single aquarium (242.27 L capacity; 76.20 cm long x 76.20 cm wide x 45.72 cm
high) on a rack that was 1.83 m high. The aquarium was part of a recirculating
water flow system that provided a continuous flow of filtered and well-oxygenated
water. However, this setup did not create directional flow within the tank. The bottom
of the aquarium was covered in a cobble–sand mixed substrate. We also fully
submerged a piece of a tree limb (~63.50 cm long and ~12.70 cm wide) in the tank.
We added the cobble–sand substrate and tree limb to the aquarium to provide a
semi-natural environment for the Laurel Dace. Approximately 2 weeks after the
fish were introduced to the aquarium, but prior to data collection, we constructed
a mound of cobble stones in the middle of the aquarium housing the Laurel Dace.
The mound was intended to resemble the nest of other minnows that inhabit the
creeks in which Laurel Dace are found, such as Campostoma oligolepis C.L. Hubbs
& Greene (Largescale Stoneroller). In one of the few observations of nest association
with Laurel Dace, nuptial Laurel Dace have been observed swimming over the
nests of Largescale Stonerollers, although spawning did not occur (Skelton 2001).
The mound was added because we hypothesized that a mound mimicking the nest of
other minnows might stimulate spawning by the Laurel Dace, as all other closelyrelated
Chrosomus (dace) species utilize the nests of mound and pit–ridge-building
minnows, such as various chub species and stonerollers, for spawning (Starnes and
Starnes 1981). We provided natural lighting through windows, allowing for ~13 h
of light to 11 h of dark during the duration of the study. The facility was climatecontrolled,
and temperature was maintained at 20.8–23.7 °C thro ughout the study.
Video-recording process
We videoed Laurel Dace 2–3 times per week for ~20 min per recording session
(see Table 1 for full details of recordings). We made all recordings between 12:00
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2019 Vol. 18, No. 3
and 16:00 from 27 April through 14 June, which corresponds with the majority of
the expected Laurel Dace breeding season (George et al. 2016). For each recording
session, we used 2 GoPro Hero 5 Blacks and/or a GoPro Hero 3 mounted on tripods
at a height of 190.50-cm. Specifically, we used each of the 2 GoPros to record 1
half of the tank. The combination of recordings from the GoPros allowed us to have
a detailed and complete recording of the entire tank for each recording session,
which subsequently allowed us to see all individuals in the tank and gather detailed
behavioral data. During each recording, the observer remained out of sight so that
disturbance would be reduced, and each recording began as soon as the observer
was out of sight.
Behavioral data collection
For each recording, we documented all behaviors hypothesized to be associated
with reproduction. Specifically, we focused on 13 potential behaviors (Table 2).
These potential Laurel Dace behaviors were based on the behaviors of other small
fish species, including Chrosomus sp. cf. saylori (Skelton) (Clinch Dace; Hatcher
et al. 2017), C. tennesseensis (Starnes & Jenkins) (Tennessee Dace; Hamed et al.
2009), and C. cumberlandensis (Starnes & Starnes) (Blackside Dace; Starnes and
Starnes 1981). Attacking (i.e., biting and nudging) and chasing tended to occur with
the territoriality behavior; thus, we quantified both the total frequency of attacking
and chasing, as well as the frequency of these behaviors when they occurred during
territoriality behavior.
Table 1. A summary of all of recording sessions.
Recording session Device used Date Time Duration (min)
1 GoPro Hero 3 27 April 2018 15:00–15:15 15
2 GoPro Hero 3 27 April 2018 15:20–15:35 15
3 GoPro Hero 3 27 April 2018 15:40–15:51 11
4 GoPro Hero 3 30 April 2018 13:00–13:20 20
5 GoPro Hero 5 30 April 2018 13:00–13:20 20
6 GoPro Hero 5 30 April 2018 13:00–13:20 20
7 GoPro Hero 5 8 May 2018 15:00–15:20 20
8 GoPro Hero 5 8 May 2018 15:00–15:20 20
9 GoPro Hero 5 9 May 2018 13:00–13:20 20
10 GoPro Hero 5 9 May 2018 13:00–13:20 20
11 GoPro Hero 5 15 May 2018 12:15–12:35 20
12 GoPro Hero 5 15 May 2018 12:15–12:35 20
13 GoPro Hero 5 21 May 2018 12:40–13:00 20
14 GoPro Hero 5 21 May 2018 12:40–13:00 20
15 GoPro Hero 5 22 May 2018 14:40–15:00 20
16 GoPro Hero 5 22 May 2018 14:40–15:00 20
17 GoPro Hero 5 30 May 2018 15:40–16:00 20
18 GoPro Hero 5 30 May 2018 15:40–16:00 20
19 GoPro Hero 5 8 June 2018 14:20–14:40 20
20 GoPro Hero 5 8 June 2018 14:20–14:40 20
21 GoPro Hero 5 14 June 2018 15:30–15:50 20
22 GoPro Hero 5 14 June 2018 15:30–15:50 20
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We manually logged the behavior observed in each recording in Microsoft
Word. We frequently stopped and re-watched the recordings, often in slow motion,
to ensure that we documented all relevant behaviors occurring in a given
video clip. After identifying all relevant behavior of all fish in each recording,
we quantified the total number of times a behavior occurred during the recording
period, in order to determine the relative frequency of each behavior observed
over all observation periods.
Table 2. Potential Laurel Dace behaviors with descriptions, the total number of observations (#), and
frequencies (freq.) at which we observed each behavior. The behaviors are presented in order from
most to least frequently observed.
Behavior Description # Freq.
Chasing One fish rapidly accelerates towards another individual. 52 35.62%
A particular form of chasing is corralling, which occurs
when individuals chase another individual back towards the
group. Corralling tends to co-occur with shoaling (described
below).
Attacking One individual swims up to another individual and bites or 43 29.45%
nudges the chest, head, or caudal fin of the other individual.
Sigmoid display The body of one fish bends into a “C” or “S” shape while 30 20.55%
swimming towards or near another fish. The body of the fish
often flops while in the “C” or “S” shape.
Chafing One individual rubs any part of its body against another 5 3.42%
individual.
Territorial behavior One individual is showing signs of aggression while staying 4 2.74%
close to a specific area or spot. This aggression can be
demonstrated through behaviors such as attacking and chasing
any other fish that come too close to the specific area or spot.
Following One individual or multiple individuals are following another 4 2.74%
individual, either from behind or from the side.
Shoaling Occurs when a group of individuals are gathered together for 3 2.05%
social reasons, including in order to reproduce.
Biting of the cloaca One individual bites the cloacal region of another individual; 3 2.05%
this is not an aggressive bite as would be seen in attacking.
Dance One individual swims close to another individual. The first 2 1.37%
individual then positions itself upright and rapidly “flaps” its
pectoral fins.
Cloacal contact One individual briefly touches another individual’s cloaca 0 0.00%
with its cloaca
Cloacal swing One individual brings their cloaca forward from a resting 0 0.00%
position without directing it towards another individual’s
cloaca.
Cloacal thrust One individual swings their cloaca toward another 0 0.00%
individual’s cloaca without making contact
Nest takeover An individual uses another species’ nest for spawning 0 0.00%
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Results
Observed behaviors
In the 421 minutes of recording across 22 recording episodes, we observed a
total of 146 events representing 9 relevant behaviors (Table 2). Below, we provide
a description of the behaviors observed, in order of highest observed frequency to
lowest frequency.
Chasing. The behavior that occurred most frequently was chasing (52 observations)
which accounted for 35.62% of the behaviors observed. Chasing was also
potentially underestimated in our study, as some chasing might have occurred
behind the tree branch while individuals were shoaling and out of view. Regardless,
chasing appears to be frequent among breeding-season Laurel Dace. We often
observed chasing when 1 territorial individual appeared to chase another individual
away from a specific spot. This territorial chasing was sometimes associated with
the mound. Numerous episodes of chasing also occurred when individuals were
gathered under the tree limb. When 1 or more individuals swam away from the tree
limb, multiple individuals chased that individual back towards the group under the
tree limb. The Laurel Dace exhibiting this type of chasing behavior appeared to
be corralling other individuals back to the tree limb. We observed this corralling 3
times (all of which were associated with the shoaling behavior) and it accounted for
5.77% of the total chasing behavior. While individuals were gathered under the tree
limb, multiple individuals also frequently chased each other around the tree limb
and back toward the group. In other instances, chasing occurred when all individuals
were swimming. This chasing typically lasted ~5 sec, and then the individuals
dispersed. The short duration for the chasing behavior could be due to the size of
the aquarium. Longer chasing durations might be expected in a l arger aquarium.
Attacking. We made 43 observations of attacking behavior, which accounted
for 29.45% of the behaviors observed. The attacking behavior typically involved
1 territorial individual biting or nudging the body or caudal fin of another individual.
In a few cases, 1 individual attacked another individual in the absence
of territoriality. The most extreme case of this attacking behavior occurred in 1
recording during which 2 individuals attacked each other approximately every 15
sec over a 2-min period.
Sigmoid display. A relatively short variation of a sigmoid display accounted for
20.55% of the behaviors observed (30 observations). In this behavior, an individual
flexed into a strong “S” position and rapidly flopped its body once, either at another
individual, on the substrate close to another individual, or on the substrate without
another individual present. Fifteen of the total 30 sigmoid displays (50%) were
exhibited on the substrate. Although we did not directly observe spawning, it is
possible that this behavior occurred during or before spawning, given that it often
involved 2 or more individuals and frequently occurred on or ne ar the substrate.
Chafing. Chafing accounted for 3.42% of the behaviors observed (5 observations).
However, it is possible that additional chafing occurred while individuals
were shoaling; when individuals are shoaling it is difficult to observe them in
the middle of the group. We typically observed chafing when individuals were
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2019 Vol. 18, No. 3
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gathered under the tree branch. We occasionally observed chafing when individuals
were swimming.
Territoriality. Territoriality occurred at a frequency similar to chafing, and
accounted for 2.74% of the behaviors observed (4 observations). Territoriality
was always exhibited by a single individual. During territoriality, an individual
appeared to guard a specific spot. This spot was sometimes associated with the
mound. Unique to territoriality, other behaviors occurred simultaneously, including
attacking (i.e., biting and nudging) and chasing off individuals that came in close
proximity to the area appearing to be guarded. We observed these behaviors occurring
with territoriality (attacking and chasing) a total of 81 times. We observed
attacking behavior 43 times during all recordings (with and without territoriality),
and 34 (of these 43) instances occurred during territoriality, accounting for 41.98%
of the associated behaviors observed with territoriality. We observed chasing a total
of 52 times during all recordings, and 47 of these instances of occurred during
territoriality, accounting for 58.02% of the behaviors observed with territoriality.
When observed, territoriality and its associated behaviors generally persisted for
the entire recording.
Following behind. Following behind accounted for 2.74% of the behaviors observed
(4 observations). Typically, at least 1 individual followed a single Laurel
Dace for 10–15 sec.
Shoaling. Shoaling accounted for 2.05% of the behaviors observed (3 observations).
In one instance, approximately 18–20 individuals gathered tightly under a
small portion of the tree limb. In the other instances, ~8–12 or 15–18 individuals
grouped together. Laurel Dace shoaled in what appeared to be an unorganized way.
That is, in most instances, they did not all face the same direction, and they swam
in either a loose or tight formation (i.e., there did not appear to be consistency in
the formation of the group). The loose formation consisted of Laurel Dace swimming
out and circling the group, and then returning back to the group. The tighter
formation consisted of all or most of the Laurel Dace staying tightly in the group.
Thus, under the conditions of this study, from a captive group of 25, it appears that
shoaling groups typically involved a subset of between 8 and 20 individuals. As
previously mentioned, corralling was associated with all 3 shoa ling observations.
Biting of the cloaca. Biting of the cloaca accounted for 2.05% of the behaviors
observed (3 observations). When we observed this behavior, 1 individual bit or
nudged another individual on or around the cloaca and then either swam away or
swam next to another individual and repeated the behavior with that new individual.
Dancing. Dancing occurred the least frequently, and accounted for 1.37% of the
behaviors observed (2 observations). When dancing occurred, 1 individual swam
close to another individual, positioned itself upright, and rapidly “flapped” its pectoral
fins. This behavior lasted only a few seconds, and then the individual either
swam away or remained next to the other individual.
We did not observe cloacal contact, cloacal swings, cloacal thrusts, or nest takeovers,
nor was spawning ever directly observed. However, throughout the study
period, TNACI biologists collected eggs on 5 occasions and found a total of 987
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eggs and larvae. Thus, breeding did occur during the 2018 mating season under the
conditions at TNACI.
Discussion
We have documented several behaviors that occur during the Laurel Dace breeding
season. These behaviors include chasing, attacking, a sigmoid display, chafing,
territoriality, following behind, shoaling, biting of the cloaca, and a dance (see also
Table 2). Some of these observed behaviors are consistent with the behaviors that
have been commonly observed in other dace species, while other behaviors appear
to be unique to Laurel Dace. Behaviors commonly seen in other dace that were also
exhibited by Laurel Dace include chasing (also seen in Blackside Dace, Tennessee
Dace, and Clinch Dace), territorial chasing (also seen in Tennessee Dace and
Clinch Dace), following (also seen in Tennessee Dace), and corralling (also seen
in Blackside Dace) (T. Black, NC Wildlife Resources Commission, Creedmor, NC,
pers. com.; Hamed et al. 2009; Hatcher et al. 2017; Starnes and Starnes 1981).
To the best of our knowledge, the sigmoid display and the dance behavior exhibited
by Laurel Dace have not previously been observed in other dace. While
there have been sigmoid displays exhibited by other dace, such as the Blackside
Dace, these displays differ from the one exhibited by Laurel Dace (T. Black, pers.
comm.). Laurel Dace do not press another fish to the substrate or near the substrate
while doing their sigmoid display, and the display is extremely rapid and brief. Additional
observations are needed to determine the function of the various behaviors.
Future research should also be conducted to further examine the territorial behavior
of Laurel Dace. We were unable to determine if territorial individuals were protecting
a given area or if they were guarding fertilized eggs deposited or buried in
the substrate. If the individuals were guarding fertilized eggs, this behavior would
suggest that Laurel Dace exhibit parental care.
We should note that the spawning behavior of all of the mentioned sister species
of Laurel Dace are associated with the nests of other minnows (Hatcher et al. 2017).
However, we cannot determine if the eggs laid by Laurel Dace were associated with
the mound. Future research should explore whether a mound is an essential component
of Laurel Dace reproduction. Laurel Dace also exhibited cleaning behavior
(i.e., biting at the substrate to remove debris). The cleaning behavior could be associated
with cleaning the substrate before spawning, cleaning the substrate around
fertilized eggs, or searching for food. We observed cleaning in multiple locations
of the aquarium, including on and around the mound.
In addition to documenting some reproductive season behavior of Laurel Dace
during its breeding season, we also found that, under the conditions of our study,
Laurel Dace can reproduce in a lab setting. During our study, successful reproduction
occurred given that fertilized eggs were removed from the aquarium substrate
and successfully hatched and reared, which indicates that individuals were in
breeding condition and likely suggests that at least some of the behaviors observed
were associated with reproduction. Additional research is needed to determine if
similar or different behaviors are exhibited during the non-breeding season.
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Acknowledgments
The Tennessee Wildlife Resource Agency, the US Fish and Wildlife Service, and Approval
Number 17-01, and the Tennessee Aquarium and Tennessee Aquarium Conservation
Institute Animal Health and Welfare Committee provided our collection permits. The work
presented herein served as the basis for a Departmental Honors Thesis for C.T. Cronnon at
the University of Tennessee at Chattanooga. This material is based upon work supported
by the National Science Foundation under Grant No. 1552721 to H. Klug. Funding for this
project was also provided by the Tennessee Wildlife Resource Agency and the US Fish and
Wildlife Service. We thank Warren Stiles and George Gavrielides for assistance with fieldwork
and Alexandra Miles, Angela Maroti, Shannon Murphy, and Elora Hunt for assistance
with Laurel Dace husbandry. We are grateful to Sarah Farnsley, at the University of Tennessee
at Chattanooga, and the two referees of this manuscript for providing feedback on
aspects of this work.
Literature Cited
George A.L., B.R. Kuhajda, and D.A. Neely. 2016. Recovery plan for the Laurel Dace
(Chrosomus saylori). US Fish and Wildlife Service, Atlanta, GA. 63 pp.
Hamed, M.K., F.J. Alsop III, and T.F. Laughlin. 2008. Life-history traits of the Tennessee
Dace (Phoxinus tennesseensis) in northeast Tennessee. American Midland Naturalist
160(2):289–299.
Hatcher, H.R., M.J. Moore, and D.J. Orth. 2017. Spawning observations of Clinch
Dace: Comparison of Chrosomus spawning behavior. American Midland Naturalist
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Skelton, C.E. 2001. New dace of the genus Phoxinus (Cyprinidae: Cypriniformes) from the
Tennessee River drainage, Tennessee. Copeia 2001(1):118–128.
Starnes, L.B., and W.C. Starnes. 1981. Biology of the Blackside Dace Phoxinus cumberlandensis.
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