The Horrors of Sturgeon Matrimony 

in the Delaware Estuary

Scutes of Death

Matt Fisher – Delaware Division of Fish 

and Wildlife

Dewayne Fox and Matt Breece –

Delaware State University
Background

• In 2005 DFW began 

tracking reports of 

sturgeon carcasses

– Reported in DE DFW 

ASMFC sturgeon 

compliance report

– DSU created this poster 

to generate reports

– Brown and Murphy 

2010 –Fisheries
Study Area

• Ports range from river km 97 

to 203 and over 3000 deep 

draft vessels visit annually

– This long distance into the 

freshwater of an estuary is 

unusual

• Port complex of Philadelphia, 

6

th busiest port in the U.S. 

(behind Houston, L.A., NY, 

New Orleans, San Fran)

• Vessels travel estuary through 

a shipping channel maintained 

at 40’ by the U.S. ACOE

– Other commercial and 

recreational vessels travel 

daily

Figure1. Brown and Murphy 2010
Methods

• Collect genetic tissue, spine for A+G, muscle 

tissue for contaminants

• Measure carcass

– If not whole use ratio to extrapolate measurements to 

estimate live length

• Take pictures, assess cause of death, determine 

sex, scan for tags

• Mark with orange spray paint and bury on site or 

back at the office 

• Report shortnose carcasses to NMFS salvage 

network
Carcass Locations

• Also received reports from

– Nanticoke R., NJ and RI coast

• Brown and Murphy 2010-currents 

drive more carcasses to DE side

– Prevailing winds likely counteract 

the effect and reporting rate is 

effecting reports

71% 

Land

29% 

Water
Carcass reports annual frequency

0

5

10

15

20

25

30

2005 2006 2007 2008 2009 2010 2011
If you find a sturgeon, please report it immediately: 

302-735-8650. Don’t forget to include an exact location 

and contact information in your message.

Have you seen a sturgeon recently?
Carcass reports annual frequency

0

5

10

15

20

25

30

2005 2006 2007 2008 2009 2010 2011

Mean=8.2

Mean = 17.5
Carcass reports by month

0

10

20

30

40

Frequency
Carcass reports by month

0

10

20

30

40

Frequency

Juveniles

Adults
Carcass reports by month

0

10

20

30

40

Frequency

Juveniles

Adults sturgeon matrimony...

interrupted
Carcass reports by month

0

10

20

30

40

Frequency

Juveniles

Adults sturgeon matrimony...

interrupted

Just passing through for a 

snack....

BAD decision
Spring Adults

• Funnel shape estuary 

brings sturgeons into 

vessel path

• Vessel strike carcasses 

are also being 

monitored in other 

systems

– James R. occurring @ 

constriction point

– Hudson R. –unknown 

location
2008 Atlantic Sturgeon Depth in the 

Delaware Estuary by Month

0

5

10

15

20

25

30

35

April

n=322

May

n=519

June

n=7127

July

n=6266

August

n=15722

September

n=10636

October

n=5384

Depth (m)

Federal Channel >40'
2008 Atlantic Sturgeon Depth in the 

Delaware Estuary by Month

0

5

10

15

20

25

30

35

April

n=322

May

n=519

June

n=7127

July

n=6266

August

n=15722

September

n=10636

October

n=5384

Depth (m)

Federal Channel >40'

During peak carcass report season juvenile sturgeon are on 

the move and not close to the bottom as frequently as they 

are in the summer months
Carcass cause of Death

38% 

unknown

62% 

vessel 

strike
Injuries

• 18 lethal gash (head, dorsal 

area, caudal area)

• 14 decapitation

• 19 tail cut off

• 2 blunt force trauma

– 2 no visible injuriesnatural causes

– 11 too decomposed to 

ascertain

– 10 unknown due to lack 

of photo or info

• 0 gashes or trauma to 

ventral areas only
Deep draft vessel strikes

Dredged to

40’ depth

• Fully loaded deep draft vessels are known to drag bottom in depositional 

areas at low tide, hence the need for annual maintenance dredging (pers. 

com, U.S. ACOE)

• Propellers on large vessels pull water at 9 m/sec
• Dead sturgeon like most fish with 

a swim bladder float belly up

• If vessel strike injuries are postmortality then why are injuries 

never found on the ventral side?

• The mechanism that causes the 

strike to occur is poorly 

understood

– Noise negative, positive, 

neutral?

Small vessel strikes

• C+D canal report

– Recreational boater 

reported seeing a sturgeon 

jump ahead of him and 

then looked behind and 

saw the floating carcass 

(DNREC law enforcement 

report, M. Grahofski) 

• Commercial crabber 

reported hitting an adult 

sized sturgeon w/ 

outboard (DNREC C. 

Shirey pers. comm.)
Discussion – Solutions?

• Yield to sturgeon

– decrease traffic or time 

of year restriction?

– not likely or realistic 

economically/politically

• Slow, sturgeon crossing

– Speed limit in problem 

areas?

• Sturgeon at work

– Detour
Credits

• NJDEP, USCG, PAFBC, DFW trawl survey, DFW 

shorebird survey, DFW law enforcement and 

public reporters

• DSU and DFW law enforcement for following 

up on reports

• Co-workers Jared and Cathy for working up 

stinky carcasses when I’m away on vacation