The study examined the stomach contents of spiny dogfish sharks captured off the coasts of North Carolina and Virginia. 19% of dogfish contained dismembered prey remains. Atlantic menhaden remains were found that were up to 45% the length of the dogfish. Other partially digested species also suggested dogfish may consume prey larger than themselves. However, statistical analysis found no significance between prey and predator size ratios or preference for particular menhaden sizes. The results indicate spiny dogfish are not limited by gape size when preying on menhaden and dismembering large prey.

1. Spiny
Dogfish,
Squalus
acanthias,
Dismemberment
and
Consump7on
of
Large
Prey
Kailyn
Corriher,
Chuck
Bangley,
Roger
Rulifson
Department
of
Biology,
East
Carolina
University
Spiny
dogfish
(Squalus
acanthias)
is
a
small,
highly
migratory
coastal
shark
that
inhabits
all
waters
of
the
world
except
in
the
tropics.
Spiny
dogfish
have
long
been
suspected
of
being
a
top-­‐level
predator,
dismembering
and
consuming
fishes
up
to
their
own
size
(Bangley
and
Rulifson
2014).
Data
on
rela7ve
prey
size
are
lacking,
mostly
due
to
the
high
propor7on
of
dismembered
and
uniden7fied
prey
in
most
dogfish
diet
studies.
Using
stomach
contents
collected
from
dogfish
captured
by
trawl
off
of
North
Carolina
and
Virginia,
we
have
aRempted
to
back-­‐calculate
the
total
length
of
dismembered
Atlan7c
Menhaden
(Brevoor2a
tyrannus)
and
other
species
found
in
the
dogfish
diet.
M
E
T
H
O
D
S
R
E
S
U
L
T
S
I
N
T
R
O
D
U
C
T
I
O
N
• 19%
of
Spiny
dogfish
had
dismembered
contents
• Menhaden
up
to
45%
of
the
dogfish
length
were
found
in
the
stomach
contents
• The
par7al
remains
of
other
species
suggest
that
dogfish
may
be
consuming
prey
of
even
larger
rela7ve
sizes
• Results
suggest
there
is
low
significance
to
the
prey
size
in
rela7on
to
dogfish
size
• Dogfish
are
not
limited
by
gape
size
when
preying
on
Menhaden
• Nearly
significant
preference
for
par7cular
Menhaden
size
R
E
F
E
R
E
N
C
E
S
• Samples
of
mature
Spiny
dogfish
collected
by
trawl
from
Chesapeake
Bay
to
Cape
HaReras
• Gut
contents
collected
using
gastric
lavage
(Bangley
et
al.
2013)
• Measured
lengths
of
predator
and
prey
• Iden7fied
each
species
in
gut
• Back-­‐calculated
dismembered
lengths
to
determine
size
ra7os
(head:total
length)
There
is
no
sta7s7cal
significance
among
Menhaden
sizes
in
the
probability
of
dismemberment
by
Spiny
dogfish.
DF
Chi2
Chi2
Probability
1
0.2277553
0.6332
Using
back-­‐calculated
Menhaden
lengths,
the
graph
suggests
that
dogfish
between
the
sizes
of
875-­‐975mm
can
dismember
Menhaden
up
to
45%
of
dogfish
total
length.
DF
Chi2
Chi2
Probability
1
0.1398549
0.0514
There
is
no
sta7s7cal
significance
between
the
prey
and
predator
total
length
ra7o
as
predator
total
length
increases.
Back-­‐Calculated
Menhaden
Lengths
versus
Dogfish
Total
Length
Prey/Predator
RaEo
versus
Dogfish
Total
Length
Chance
of
Dismemberment
of
Menhaden
by
Spiny
Dogfish
DISMEMBERED SPECIES LIST
Squid (Teuthida)
Sand Lance (Bammodytes americanus)
Octopus (Octopoda)
Unidentified Fish (Teliosti)
Peneaid Shrimp (Penaeidae)
Common Octopus (Octopus vulgaris)
Bay Anchovy (Anchoa mitchilli)
Striped Bass (Morone saxatilis)
Smallmouth Flounder (Etropus microstomus)
Atlantic Menhaden (Brevoortia tyrannus)
Mantis Shrimp (Stomatopoda)
Weakfish (Cynoscion regalis)
Unidentified Herring (Clupeidae)
Goby spp (Gobiidae)
Summer Flounder (Paralichthys dentatus)
Unidentified Flatfish (Pleuronectiformes)
American Eel (Anguilla rostrata)
Unidentified Shrimp (Caridea)
Bangley,
C.
W.,
and
R.
A.
Rulifson.2014.
Feeding
Habits,
Daily
Ra7on,
and
Poten7al
Predatory
Impact
of
Mature
Female
Spiny
Dogfish
in
North
Carolina
Coastal
Water.
668-­‐670. Bangley,
C.
W.,
R.
A.
Rulifson,
and
A.
S.
Overton.
2013.
Evalua7ng
the
Efficiency
of
Flushed
Stomch-­‐tube
Lavage
for
Collec7ng
Stomach
Contents
from
Dogfish
Sharks.
12(3):523-­‐533.
Top:
Dismembered
Octopus
BoRom:
Dismembered
Menhaden