Transcript
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
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