Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) in the New York Bight DPS: 

Identification of critical habitat and rates of interbasin exchange 

NOAA Award NA08NMF4050611 

Final Report December, 2010 

Submitted by Dewayne A. Fox and Matthew W. Breece 

Department of Agriculture and Natural Resources 

Delaware State University 

Dover, DE 

19901 
Introduction 

The Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is one of 27 species 

within the family Acipenseridae and one of nine species/subspecies extant in North 

American waters (Cech and Doroshov 2004). Atlantic sturgeon historically occupied all 

major river systems along the Atlantic coast between Canada and Florida, with the 

Delaware River historically supporting the largest population (Secor and Waldman 

1999). The U.S. commercial fishery for Atlantic sturgeon had its roots in the Delaware 

River (Saffron 2002) and by the late 1800’s a booming fishery was established focused 

on both caviar and meat (Ryder 1888, Cobb 1900). Unfortunately, this fishery was very 

short lived and by 1891 the State of New Jersey passed legislation to protect sturgeon in 

the waters of Delaware River, bay, or tributaries within state jurisdiction (Vroom and 

Lanning 1895). In 1990, the Atlantic States Marine Fisheries Commission (ASMFC) 

produced a Fishery Management Plan (FMP) for the Atlantic sturgeon with a stated goal 

of restoring the species throughout its range to allow an annual harvest of 10% of the 

peak catch totals (≈317 metric tons; Smith and Clugston 1997). Following a petition to 

list the Atlantic sturgeon under the Endangered Species Act, a status review was 

conducted in 1998 eventually determining the species did not warrant additional 

protection under the ESA (NOAA and USFWS 1998) , although the ASMFC imposed a 

coastwide moratorium during the same year (ASMFC 1998). In 2005, the NMFS 

initiated another status review of the Atlantic sturgeon based on the conclusions of a 2003 

NMFS/USFWS joint committee. The status review team released their recommendations 

in February 2007 which stated three of the five distinct population segments of Atlantic 

sturgeon be listed as threatened under the ESA, including the New York Bight Distinct 
Population Segment (DPS) that includes the Delaware River population (NOAA and 

USFWS 2007). One finding of the SRT was the overall lack of basic biological data for 

many of the Atlantic sturgeon subpopulations including the New York Bight DPS. On 

October 6, 2010 the NMFS proposed listing of five distinct population segments under 

the ESA with the New York Bight and three other DPS proposing to be listed as 

Endangered (NOAA and USFWS 2010). 

In addition to over-fishing, Atlantic sturgeon were likely impacted by 

anthropogenic changes to spawning habitat resulting from channel modifications in the 

Delaware River Estuary (Albert 1988). These navigation projects resulted in removal of 

over 1.5 x 108

 m3 of sediment and major changes in substrate composition, tidal flows, 

and salinity concentrations as a result of this dredging (Di Lorenzo et al. 1993, Walsh 

2004). Alterations of flow and thermal regimes may impact the recovery of New York 

Bight DPS Atlantic sturgeon. Changing weather patterns may ultimately lead to an 

uncoupling of moderately increasing temperatures and spring freshets that have been 

linked to spawning in the closely related Gulf of Mexico sturgeon (A. o. desotoi) (Fox et 

al. 2000). 

In August 2009, the first successful spawning of Atlantic sturgeon in three 

decades was confirmed through the capture of multiple recently spawned (1 year old or 

less) Atlantic sturgeon (DNREC 2009). The confirmation of an extant natal population 

of Atlantic sturgeon further stressed the need for better information on the location and 

nature of current spawning habitat in the Delaware River Estuary. The most recent 

research on the location of spawning areas for Atlantic sturgeon was conducted almost a 

century ago and was derived from fishery dependent data collected before the collapse of 

the fishery in the 1890’s (Borodin 1925). 
The recent topic of DPS has been heavily debated by Atlantic sturgeon 

researchers (Grunwald et al. 2008). The 2007 Status Review recommends dividing the 

US populations into 5 DPSs based on all available data. This recommendation was based 

on a lower sample size, fewer populations and nuclear DNA as opposed to mitochondrial 

DNA examined in 2008 by Grunwald et al. Grunwald et al. (2008) further question the 

validity of DPSs entirely due to the current reproductive isolation of river specific 

Atlantic sturgeon populations. The grouping of multiple river systems into a single DPS 

may limit understanding and recovery of some populations (Grunwald et al. 2008). As a 

result of the underlying need for information of stock structure, resource managers 

require further clarification of homing fidelity and interbasin exchange of Atlantic 

sturgeon. 

Most published work on Atlantic sturgeon has focused on the juvenile phase of 

their life history (i.e. Brundage and Meadows 1982, Shirey 1997, Simpson 2008) due to 

their riverine residency and relative ease of capture. The topic of Atlantic sturgeon 

habitat requirements has recently been moved to the forefront in the Delaware River 

Estuary as resource managers are facing renewed dredging by the Army Corps of 

Engineers (ACOE) as part of the Delaware River Main Stem and Channel Deepening 

Project. 

Research on adult Atlantic sturgeon movements during the coastal phase of their 

life history is very limited. Recent research by Erickson et al. (in press) has shown broad 

movements of adult Atlantic sturgeon from Nova Scotia to GA. Although this research 

has documented previously undocumented movement patterns the sample size was small 

and entirely from the Hudson River population. Movement data has been collected from 

the bycatch of Atlantic sturgeon during scientific research efforts and commercial 
fisheries, but knowledge of the Atlantic sturgeon’s seasonal and long term movements, 

habitat utilization, distribution, and migratory behavior are lacking (Bain et al. 2000, 

Stein et al. 2004a, Laney et al. 2007, and Grunwald et al. 2008). 

Atlantic sturgeon are thought to migrate into coastal Atlantic waters for foraging 

after leaving their spawning rivers (Dovel and Berggren 1983). An examination of 

fisheries dependent bycatch data off the northeastern coast of the US indicates that 

Atlantic sturgeon primarily occupy shallow inshore areas of the continental shelf, in 

depths less than 60m (Stein et al. 2004a). During the winter Atlantic sturgeon are 

thought to migrate in a southerly manner with segments of the population occupying 

shallow nearshore waters from Cape Henry, Virginia to Hatteras, NC at depths usually 

less than 18m (Laney et al. 2007). Coastal features including inlets and the mouths of 

bays are thought to hold higher concentrations of Atlantic sturgeon (Stein et al. 2004a , 

Laney et al. 2007). This behavior is consistent with green sturgeon, (A. medirostris) on 

the west coast (Erickson and Hightower 2007). There is also a growing body of evidence 

to suggest that adult Atlantic sturgeon utilize the lower portions of the Delaware Estuary 

for prolonged periods of time during the summer months (Simpson 2008, D. Fox, 

unpublished data). 

Atlantic sturgeon are highly migratory and have been known to move great 

distances. Atlantic sturgeon captured and tagged in CT waters were recaptured from MD 

to NH, with the direction of travel being north in the summer and south in the fall and 

winter (Savoy and Pacillo 2003). More recent research conducted using pop-up satellite 

archival transmitters (PSAT) tags attached to adult Atlantic sturgeon in the Hudson River 

documented movements between the Bay of Fundy, Canada and GA coastal waters 

(Erickson et al. In Press). These recent findings follow the general patterns outlined in 
previous studies on Atlantic sturgeon (Dovel 1979, Smith 1985, Shirey 1995). In 

addition to these migrations juvenile sturgeon have been shown to aggregate on overwintering areas off the coast of NC and near the mouth of the Hudson River (Laney et al. 

2007 and Savoy and Pacillo 2003). 

The bycatch of Atlantic sturgeon occurs in a wide variety of gear types from ME 

to NC, generally increasing from north to south (Stein et al. 2004b). Bycatch events are 

highest in the fall, winter and spring when sturgeon are thought to be moving coastally to 

and from spawning grounds and lowest in the summer months (Stein et al. 2004b) when 

Atlantic sturgeon are believed to enter estuarine and riverine habitats (Simpson 2008). 

Recent unpublished evidence has revealed that confined summer aggregations of both 

adult and juvenile Atlantic sturgeon occur in polyhaline marine waters (Simpson 2008, 

and Fox unpublished data), this lack of movement may be the reason for reduced bycatch 

and not absence from marine waters. 

Project Objectives 

Through this project we have attempted to address two primary objectives: 1: 

Confirm Atlantic sturgeon spawning in the Delaware River and begin to gather data (e.g., 

location of spawning grounds, spawning intervals, genetic characteristics of the 

population and ultimately, population size estimates) on this subpopulation and 2: 

Estimate interbasin exchange rates between the Delaware and the Hudson rivers through 

the use of compatible telemetry systems in both rivers. 
Materials and Methods 

Study Area

 Adult Atlantic sturgeon sampling took place in marine waters 3 to 15km off the 

coast of DE in the region of the DE/MD border (Figure 1). An array of passive acoustic 

receivers (VEMCO VR-2 and VR2W) were placed in the waters Delaware River Estuary, 

off the coast of MD, DE, NJ, and the Hudson River (Figures 1 - 2). For the purposes of 

this study we consider the Delaware River to include the mainstem waters beginning at 

the Chesapeake and Delaware (C&D, RKM 94) Canal and extending upstream to 

Trenton, NJ (RKM 210) (Figure 1). The Delaware Bay is defined as the region extending 

seaward from the C&D Canal to a line drawn from Cape Henlopen, DE to Cape May, NJ 

(RKM 0) (Figure 1). The Coastal portion includes the area seaward of the mouth of 

Delaware Bay and ranges from Ocean City, MD to Hereford Inlet, NJ (Figure 1). 

Monitoring occurred in the Hudson River from the Raritan Bay (RKM 0) to Catskill, NY 

(RKM 179) (Figure 2). 

Marine Collections

Adult Atlantic sturgeon were captured using gill nets and techniques similar to 

those developed in the Atlantic sturgeon coastal intercept fishery before its closure in 

1998. Monofilament gill nets consisting of ten panels (91.0m x 6.1m) strung together 

were fished as one long net. We employed mesh sizes of either 30 or 33 cm stretch mesh, 

with a twine size of 0.90-0.98 mm, and a hanging ratio of 0.5. A total of four gillnets 

were fished daily for approximately 6-8 hours each day tending the nets every 2-3 hours 

to reduce the stress and potential mortality on any Atlantic sturgeon captured. Each 

gillnet was also outfitted with acoustic pingers (Fumunda, specs (freq. 10 kHz, power 132 
dB) at the beginning of the net and at the junction of each gillnet panel to help deter 

marine mammal interactions. 

Water temperature, and salinity were recorded at the start of each gillnetting 

location using a Yellow Springs Institute, YSI 85 and substrate samples were taken using 

a Petite Ponar® to determine bottom composition on both ends of the netting locations. 

Soak time was defined as the time from the net first entering the water until the 

completion of hauling. The start and end points of each net deployment were recorded 

with a GPS and depth was recorded with a hull mounted echosounder. 

Handling and Surgical Procedures

 Upon capture, Atlantic sturgeon were placed in a live well (≈1,100 l), with water 

pumped in directly from the ocean, maintaining ambient temperature, salinity and 

dissolved oxygen levels. All individuals were measured (FL and TL) to the closest cm 

and weight was measured to the closest kg using a hanging scale. Atlantic sturgeon were 

scanned for the presence of a passive integrated transponder (PIT) tag, using an AVID® 

Power Tracker VIII or Biomark® FST2001FT PIT tag reader, and monitored for the 

presence of an existing VEMCO Ltd. acoustic transmitter using a VEMCO Ltd. VR-100 

and hydrophone. If no PIT tag was found, a 16mm Biomark® PIT tag (model IMI 1000, 

400 kHz) was inserted on the left side of the fish at the base of the dorsal fin (Fuller et al. 

2008). A tissue sample was taken from the caudal fin and placed in 95% ethanol for 

genetic analysis. A USFWS plastic-t-bar tag was inserted on the left side of the fish at 

the base of the dorsal fin following established protocol (Damon-Randal et al. 2010). 

 Implantation protocols developed by Fox et al. (2000) for Gulf of Mexico 

sturgeon were utilized to implant acoustic transmitters (VEMCO V-16, 6-H, 69.0 kHz). 

All sturgeon were handled with the assistance of a sling to reduce stress and injury to 
both researchers and the Atlantic sturgeon; the sling consist of a 1.3 m x 2 m coated 

canvas strung between two 3 cm x 2.2 m wooden poles. Suitably sized (>1.3m FL - 

Van Eenennaam et al. 1996) individuals were transferred to a 900 l anesthetic tank 

containing tricaine methane sulfonate (MS-222®) and seawater at a dosage of 150 mg/l 

(Harms and Bakal 1994). Upon loss of equilibrium and signs of slowed respiration, 

individuals were placed in a sling, ventral side up, while their head and gills remained 

submerged. An incision was made off center on the abdomen, and a transmitter (90mm 

x 16mm, in-water weight of 14g, off-time of 75-105 seconds and an approximate 6 year 

battery life) was inserted into the body cavity. When possible a gonadal tissue sample 

was taken and placed in a vial containing 10% buffered formalin for sexual identification 

and reproductive stage (Van Eenennaam et al. 1996). Acoustic transmitters were coated 

with Factor2 Platinum Silicone Elastomer®, a biologically inert compound, in an attempt 

to minimize rejection rates (Boyd Kynard, USGS, Conte Anadromous Fish Laboratory, 

personal communication). Four to six sutures were used to close the incision using 

sterilized suture material (PDSII, size 1) and petroleum jelly mixed with Betadine® 

ointment to coat the site to minimize infection. Oxytetracycline (OTC, 200mg/mL) was 

administered as a prophylactic antibiotic at a dose of 1.0mL per 20kg body weight near 

the base of the dorsal fin, with a half-dose anterior to the PIT tag and a half-dose 

posterior of the PIT tag. Atlantic sturgeon larger than 20kg received the OTC at a 

maximum of 0.5mL in one injection site to prevent encapsulation. At the completion of 

surgery Atlantic sturgeon were transferred to a 1,100 l recovery tank and monitored. 

After regaining equilibrium, individuals were released near the location of capture by 

gently lowering the fish, using the sling, into the water. 
Telemetry

The existing passive listening array in the Delaware River Estuary, and off the 

coast of MD, DE and NJ (Figure 1) was maintained and expanded throughout the study. 

A new passive array was also established in the Hudson River and the New York Harbor 

to monitor the presence of telemetered Atlantic sturgeon (Figure 2). The arrays consisted 

of VEMCO Ltd. VR-2 and VR-2W receivers, which were comprised of a hydrophone, 

internal data storage and battery (expected life 18 months). The receivers are designed to 

detect and record the identification codes of VEMCO Ltd. ultrasonic transmitters within 

range of the receiver along with the time, date, and sensor data (if present). The receivers 

were moored either to United States Coast Guard (USCG) aids to navigation (ATON) or 

independently to concrete blocks and downloaded on an approximately monthly basis. 

The detection range of these receivers depends on site location and weather conditions 

although ranges of 0.5km - 2.8km are commonly encountered (Simpson 2008). 

In 2010 we deployed eight passive acoustic receivers approximately 2 km south 

of the area where gillnetting occurred in addition to the existing passive array to help 

direct sampling efforts. These receivers were deployed in a line perpendicular from shore 

and spaced out every 2 km to help determine the pathways utilized by previously 

telemetered Atlantic sturgeon (Figure 3). 

Environmental data associated will all detections were taken from one of 3 

sources; Marcus Hook, PA NOAA station 8540433 for Delaware River data, 9 miles off 

of Fenwick Island, DE NOAA station 44009 for DE coastal data, and The Battery, NY 

NOAA station 8518570 for Hudson River data. 
Spawning Locations 

Telemetered adult Atlantic sturgeon were tracked by the passive acoustic array as 

the entered the Delaware River, then a more detailed monitoring approach utilizing 

passive and active telemetry was employed until telemetered adults left the River or 

water temperature exceeded 25 C, the maximum known spawning temperature for 

Atlantic sturgeon (Dovel and Berggren 1983). When adult Atlantic sturgeon occupied 

areas where suitable habitat was thought to exist (i.e. flowing freshwater and hard bottom 

habitats) (Gilbert 1989 and Smith and Clugston 1997) sampling for fertilized eggs was 

conducted using an array of egg samplers. These egg samplers consisted of a 56cm 

diameter floor buffing pad which had an abrasive surface suitable for the adhesion of 

sturgeon eggs. We measured depth, temperature, oxygen, substrate composition, and 

conductivity at three locations within the array of eggmatts in an attempt to characterize 

spawning site characteristics. This method of using telemetered fish to direct placement 

of artificial substrates has proven successful in both shortnose (A. brevirostrum) (Kieffer 

and Kynard 1993) and Gulf of Mexico sturgeon (Fox et al. 2000). 

Genetics 

 Tissue samples collected from all Atlantic sturgeon captured during marine 

collections were sent to Tim King (USGS) and Ike Wirgin, (New York University School 

of Medicine) to determine the likely rivers of origin and the population structure of the 

individuals sampled. 

Cooperative Research

 Through the development of collaborative data sharing arrangements with 

researchers using compatible telemetry equipment in other river systems and along the 

eastern seaboard we were able to expand the detection areas of telemetered adult Atlantic 
sturgeon outside of our primary array. Additionally, we were able to utilize telemetered 

adult Atlantic sturgeon from other regions (i.e. Hudson River and Long Sound) outfitted 

with compatible acoustic transmitters when they were detected in our primary array. 

Results 

Marine Collection 

2009 

We initiated sampling on March 18 and concluded on April 26, 2009 (Table 1) for 

a total of 20 sampling events; deteriorating weather conditions lead us to censure our 

efforts on April 21 from future analyses. All sampling efforts took place 3 to 15 

kilometers off the Delaware coastline between an area bordered by the Indian River Inlet 

to the north and the Delaware State line to the south (Figure 4). In total we exerted 

7,398.9 100m/hours of sampling effort during the 2009 sampling season. As a result of 

these efforts we landed 55 Atlantic sturgeon on 13 days (Table 1). Sampling was 

initiated when water temperatures were approximately 5 o

C although we had limited 

success until temperatures reached 8 oC. 

 In the first year of sampling Atlantic sturgeon averaged 163 cm (range: 120-

226cm) in length and 49 kg (range: 21-93 kg) in weight (Table 2). Based on a minimum 

size of 1.3m FL (Van Eenennaam et al. 1996) 54 of the 55 sturgeon captured were of 

minimum size to have reached maturity. We encountered a total of four Atlantic 

sturgeon mortalities all of which took place prior to the cessation of overnight sampling 

events. Following these mortalities we changed our sampling strategy and no additional 

mortalities occurred during the remainder of the study period. All 51 sturgeon captured 

and released alive received long-lived (>6 year) ultrasonic transmitters. 
2010 

During the 2010 sampling season we initiated our sampling when water 

temperatures reached 7°C as we saw limited success in water temperatures below 8°C in 

2009. We conducted a total of 17 sampling events from March 28 to April 23, 2010 

(Table 3). All sampling efforts took place in the same area as in 2009 (Figure 3). Effort 

totaled 4952.4 100m/hours during the sampling season, resulting in the capture of 54 

Atlantic sturgeon on 13 days (Table 3). 

 In the second sampling season collected Atlantic sturgeon averaged 163cm 

(range: 119-230cm) in length and 47kg (range: 19->110 kg) in weight (Table 4). Fifty 

Atlantic sturgeon we handled were large enough (>1.3m FL) to have reached sexual 

maturity. Thirty-nine of the 50 adult Atlantic sturgeon captured received long-lived (>6 

year) ultrasonic transmitters, the remaining 15 received only PIT tags and USFWS t-bar 

tags. 

 Gillnetting success was limited in both 2009 and 2010 during the first several 

sampling events. As water temperatures increased we began to have greater success with 

the greatest success occurring on the last few sampling events each year (Tables 1 and 3, 

Figures 5 and 6). While sampling later in the year may produce higher numbers of 

Atlantic sturgeon the potential presence of marine mammals and sea turtles with rising 

water temperatures increases the probability of interactions. 

Genetics 

 We have received the haplotype distributions for collected Atlantic sturgeon 

based on mitochondrial DNA and we are awaiting the results of the nuclear DNA 

microsatellites assignments. 
The genetic makeup of our collections provide insights into the stock composition 

of Atlantic sturgeon off the coast of Delaware. Of the 109 samples, 89 were assigned to 

one of 12 specific haplotypes from eight different groupings representing varying 

regional composition of the haplotypes (Grunwald et al. 2008). We are still awaiting 

assignments on the remaining individuals. Haplotypes from New York Bight distinct 

population segment (A5, B, B1, B2, C4 and C5) represent the highest number of the 

samples collected (38), followed by haplotypes from the entire range of the species (A) 

(24), and then haplotypes representing the region from the Delaware River to the 

southern extent of their range (C, and N1) (21), (Grunwald et al. 2008) (Table 5, Figure 

7). There were two samples that contained the haplotype A5 which is unique to samples 

found in the Delaware River, 4 from the Hudson River (B1, B2, C4 and C5), four from 

the Hudson south (D), one from the Edisto River (P1) and one from the Savannah River 

(P8) (Grunwald et al. 2008). 

Cooperative Research

 In addition to adult Atlantic sturgeon captured through our efforts, we were able 

to increase the sample size through collaboration with other researchers. Sixteen adult 

Atlantic sturgeon from other projects were incorporated into this research, 3 telemetered 

by Delaware State University in 2006 and 2007, seven telemetered by the CT Department 

of Environmental Protection in Long Island Sound in 2007 and 2008, and 6 from the 

University of Miami, Pew Institute for Ocean Science telemetered in the Hudson River in 

2008. Another 26 sub-adult Atlantic sturgeon were utilized in this study, 14 telemetered 

by DSU aboard the North Carolina Cooperative Tagging Cruise off the coast of North 

Carolina and Virginia (13 in 2009, 1 in 2010), and 12 from the Long Island Sound and 

Connecticut River in 2007, 2008 and 2009 by the CTDEP. 
Telemetry 

2009 

Prior to the initiation of our directed sampling for adult Atlantic sturgeon in 2009 

a large number of passive acoustic receivers (VEMCO VR-2 and VR-2W) were deployed 

in the Delaware River Estuary and near-shore coastal environment (Figure 1). The 

deployment of acoustic receivers in the Hudson River was not completed until July 24, 

2009 as a result of delays in finalizing a memorandum of agreement with the USCG. 

Immediately following approval, an array of passive receivers was deployed in the 

Hudson River to document inter-basin exchange rates (Figure 2). These receivers were 

maintained in the Hudson River until November 11, following the departure of all 

telemetered Atlantic sturgeon and prior to the formation of ice. However; through 

collaborative efforts with the University of Maryland four receivers were maintained over 

the winter in the Hudson River. 

For the purposes of this report we have partitioned the array into four strata: 1- 

Delaware River (n= 30), 2- Delaware Bay (n= 37), 3- Coastal (n= 19), and 4- Hudson 

River (n= 14) (Figures 1 and 2). 

The results of our regional approach to tracking Atlantic sturgeon proved very 

successful in 2009 as we were able to detect the vast majority (48/51) of Atlantic 

sturgeon telemetered off the coast of DE (Figure 8) and 36 telemetered Atlantic sturgeon 

from other research groups (Figure 9). We detected 83 telemetered Atlantic sturgeon in 

coastal habitats, 60 in the Delaware Bay, and four in the Delaware River (Figures 8 and 

9). Additionally, 13 telemetered Atlantic sturgeon were detected in the Hudson River 

during 2009 (Figures 8 and 9). 
2010 

The majority of passive acoustic receivers (VEMCO VR-2 and VR-2W) deployed 

in the Delaware River Estuary and nearshore coastal environment in 2009 were 

maintained throughout the winter months; however, several receivers did have to be 

removed due to threats of icing. In addition to the redeployment of receivers removed 

due to the threat of icing, 12 acoustic receivers were added to new locations in the 

Delaware Bay and Coastal portions of the array in the spring of 2010 (Figure 1). In the 

Hudson River 13 acoustic receivers were redeployed on May 11th and 12th to document 

inter-basin exchange rates. Receiver totals for the four strata were as follows: 1- 

Delaware River (n= 30), 2- Delaware Bay (n= 37), 3- Coastal (n= 23), and 4- Hudson 

River (n= 17) (Figures 1 and 2). 

 Similar to the previous sampling season the results of our regional approach to 

tracking Atlantic sturgeon proved very successful as we were able to detect all of the 39 

Atlantic sturgeon telemetered in 2010 during our marine collections (Figure 10). In 

addition, we detected most (41 of 51) of the Atlantic sturgeon telemetered during marine 

collections in 2009 (Figure 11). In total, we documented 102 telemetered Atlantic 

sturgeon in coastal habitats, 62 in the Delaware Bay, and six in the Delaware River. 

Twenty-three telemetered Atlantic sturgeon were detected in the Hudson River array. 

Coastal Movements 

 Through the use of fully compatible telemetry arrays located in the Delaware 

River and Estuary, surrounding coastal waters, and the Hudson River, we were able to 

document wide scale movements of Atlantic sturgeon along the eastern seaboard of the 

United States. Atlantic sturgeon telemetered during marine collections off the coast of 

Delaware were detected as far south as Gray’s Reef, GA (n=1), off the coast of NC 
(n=14), in Long Island Sound (n=11) and as far north as the Gulf of Maine (n=1), a 

distance of over 1800 km (Figure 12). For this report we have identified individual 

Atlantic sturgeon by acoustic transmitter number and they will displayed as # XXXXX 

and can referenced in the tables and figures by this number. 

The Atlantic sturgeon (DSU106702) detected near Gray’s Reef, GA was a 32kg 

individual of unknown sex that was collected on April 25, 2009 and identified as having 

haplotype B, which has only been shown to occur in the Delaware and Hudson Rivers 

(Grunwald et al. 2008). It remained in the Delaware Bay until June 5 (16.6 oC), utilized a 

limited reach of the Atlantic Ocean near the mouth of the Delaware Bay until September 

20 (20.7 oC) and was not detected again until March 18 and 19, 2010 in Georgia. It then 

made a northerly migration from GA and was detected off the coast of North Carolina on 

April 10 and 11 and then off the coast of MD on April 30 (11.1 oC). This individual then 

was detected in similar portions of the Delaware Bay and the Atlantic Ocean near the 

coast of Delaware as in 2009, where it remained through the end of the reporting period 

(Figure8 and 11). 

On May 16, 2010 Atlantic sturgeon DSU1084977 telemetered during the 2010 

sampling season was detected by researchers in the Gulf of Maine. This 50kg female was 

collected on April 21, 2010 and was identified as haplotype A, which has been shown to 

occur throughout the entire range of Atlantic sturgeon (Grunwald et al. 2008). This 

sturgeon was detected in Delaware Bay on April 23, off the coast of NJ on April 24 (11.2 

o

C) and then it was detected in the Gulf of Maine on May 16, just over three weeks after 

capture (Figure 10). 

An additional 11 telemetered Atlantic sturgeon were detected in the Long Island 

Sound, three of which were detected in 2009 and 2010, and 14 detected off the coast of 
North Carolina. While we have few detections from individual fish detected in the Gulf 

of Maine and near Gray’s Reef, GA, we do have more information on the Atlantic 

sturgeon that utilized the Long Island Sound and the coastal waters of North Carolina. 

Telemetered Atlantic sturgeon used Long Island Sound primarily in the summer and fall, 

detected by the receivers from June 5 to October 18. The detections of Atlantic sturgeon 

off the coast of North Carolina took place during the winter and spring December 14, 

2009 through April 29, 2010 (Figures 9 and 11). 

The coastal portion of the passive array near DE, MD and NJ was very effective 

in providing us with detailed information on timing and movement patterns of Atlantic 

sturgeon along the Delaware coastline (Figure 13). All Atlantic sturgeon utilized in this 

study that were detected to the north (e.g. Hudson River and Long Island Sound) of the 

coastal portion of the Delaware array were first detected on their migration north by the 

coastal array. No telemetered Atlantic sturgeon passed by the array undetected, whether 

ultimately being detected in the Hudson River, Long Island Sound or continuing on to the 

Gulf of Maine during its spring migration north (Figure 8, 9, 10 and 11). 

In the spring of 2009 telemetered Atlantic sturgeon arrived off the DE and MD 

coastlines from April 5 to June 5 (7.0 o

C to 16.6 oC) (median arrival date May 12 (12.3 

o

C)). These individuals then departed our coastal receivers beginning on April 6 and 

concluding on June 29 (7.6 o

C to 20.6 oC) (median departure date May 23(15.4 oC)). In 

2010 Atlantic sturgeon arrived in the coastal portion of the array from April 2 to June 23 

(7.7 o

C to 22.3 oC) (median arrival date May 2 (12.9 oC)) and departed from April 7 to 

June 25 (9.6o

C to 22.7 oC) (median departure date May 28 (15.2 oC)). Atlantic sturgeon 

that migrated through the coastal array presumably heading northward spent between 1-

64 days (median 22 days) in the array in 2009 and from 2-68 days (median 27 days) in 
2010 (Figure 14). Only returning telemetered Atlantic sturgeon were used in the 

calculation of arrival dates to avoid biases associated with in season tagging efforts. 

Atlantic sturgeon that resided in the array during the summer months were not used in the 

calculation of departure times as these individuals did not depart our region in the spring. 

During the 2010 sampling season we documented the majority of returning 

Atlantic sturgeon in relatively shallow near shore habitats as they made their migration 

northward in the spring. An examination of the passive acoustic receivers deployed to 

assist gillnetting efforts in 2010 indicated that 95% of Atlantic sturgeon detections 

occurred within 7km of shore and 85% of Atlantic sturgeon were detected within the 

jurisdictional boundary of state waters (Figure 15). The receivers located at 14 and 16km 

from shore did not detect any Atlantic sturgeon and the receivers located at 10 and 12km 

only detected two Atlantic sturgeon on their presumed northward migration. 

During the summer months in both years of this study a substantial portion of our 

telemetered Atlantic sturgeon maintained residency in the area near the mouth of the 

Delaware Bay. Sixteen telemetered Atlantic sturgeon were documented using eight 

receivers just outside the southern edge of the mouth of the Delaware Bay in 2009 

(Figure 16). These limited movements occurred from July 1 (21.7 o

C) to September 12 

(21.4o

C) and these resident Atlantic sturgeon inhabited the coastal portion of the array for 

a median of 152 days (range 114-191). We documented 25 Atlantic sturgeon occupying 

a similar although slightly broader habitat in 2010 compared to 2009. We utilized 

manual tracking to pinpoint two major aggregations of telemetered Atlantic sturgeon less 

than 2km from each other and within 3km of Cape Henlopen, Delaware. This area of 

high occupancy located at the entrance to Delaware Bay in the Atlantic Ocean is a highly 

channelized, very deep (>30m) area with very high tidal flows, gravel substrate and 
polyhaline waters. Residency times for telemetered Atlantic sturgeon utilizing this 

summering area are yet to be calculated for 2010 as telemetered Atlantic sturgeon 

occupied these habitats through the end of the reporting period. 

In total we documented 33 telemetered Atlantic sturgeon from different river 

systems and of different size classes occupying the polyhaline waters at the mouth of the 

Delaware Bay, eight of these individuals occupied this area in both 2009 and 2010. We 

obtained genetic identification for 22 of the 33. These sturgeon had six different 

haplotypes representing five regions; one from the entire range of the population 

(Haplotype A), eight from the NY Bight segment (haplotype B), ten from the Delaware 

River to the southern extent of the range (haplotypes C and N1), one from the Hudson 

River (haplotype C5) and two from the Hudson River to the southern extent of the range 

(Haplotype D) (Grunwald et al. 2008). 

In 2009, summer resident Atlantic sturgeon began to depart our array on 

September 11 (21.8 o

C). This emigration of summer residents was followed by an influx 

of telemetered Atlantic sturgeon presumably arriving from the north between September 

19 (20.8 o

C) and December 1 (13.1 oC) (median date November 3(16.1oC)); the last 

recorded telemetered Atlantic sturgeon in the coastal array occurred on December 1 (13.1 

o

C) with a median date of departure being October 16 (17.9 oC). Atlantic sturgeon which 

arrived after the departure of summer residents spent little time in the coastal array in the 

fall of 2009; of the 11 telemetered Atlantic sturgeon that migrated through the array, 10 

were detected for less than three days and one spent 30 days in the array. 

Arrival dates in the Hudson River for 2009 cannot be estimated due the delay in 

deployment of receivers and there is a possibility that some telemetered Atlantic sturgeon 

did enter and exit the river prior to deployment. On July 14-16, ten days prior to 
deployment of receivers in the Hudson River, we manually tracked from Catskill, NY 

(rkm 179) to the mouth of the river. This was done by stopping and listening with a 

manual acoustic hydrophone every 1.5km to document the presence of telemetered 

Atlantic sturgeon in the river. In doing so we documented ten telemetered Atlantic 

sturgeon occupying the river, six from our Delaware collections prior in the spring and 

four that were telemetered in the Hudson River in 2008. 

Eleven telemetered Atlantic sturgeon were detected on the receiver array in the 

Hudson River in 2009, seven from our sampling efforts, two telemetered in the Hudson 

River in 2008, and two that were telemetered aboard the North Carolina Cooperative 

Tagging Cruise in the February of 2009. A range of departure times cannot be calculated 

for the Hudson River in 2009 as we documented at least two telemetered individuals had 

departed the system prior to deployment of receivers. Telemetered Atlantic sturgeon did 

continue to utilize the Hudson River until October 12 (18.6 o

C), with eight of the 

remaining telemetered 11 Atlantic sturgeon leaving between September 13 (20.6 oC) and 

October 12. 

In 2010, 23 Atlantic sturgeon were detected utilizing the Hudson River from April 

30 (10.8 o

C) to the end of the reporting period; four individuals utilized the Hudson River 

the previous year. Telemetered Atlantic sturgeon arrived in the Hudson River on a 

median date of July 4 (21.1 o

C) (range April 30 – August 10 (10.8 oC - 23.6 oC)). 

Departure from the river began as early as May 11 (11.0 o

C) and continued throughout 

spring and summer. Due to logistical constraints the upper six acoustic receivers on the 

river have not been downloaded since June 28, 2010 but are still being maintained in the 

river. This coupled with the fact that telemetered Atlantic sturgeon continue to occupy 
the river as of the end of this reporting period prevents us from calculating departure 

dates from the river at this time. 

We do have confirmation of at least two telemetered Atlantic sturgeon departing 

from the Hudson River as they were detected in the coastal portion of the Delaware Array 

after detection in the Hudson River. These two Atlantic sturgeon (# DSU1084967 and # 

DSU 1084974) were the largest individuals captured during collection efforts. They were 

collected on April 20 and 21 and both were gravid females. Both Atlantic sturgeon 

remained near the mouth of the Delaware Bay until May 22 and 23, 2010 (14.6 oC – 15.1 

o

C) when they made a directed migration north entering the Hudson River on May 29 

(16.2 oC). They were detected as far north as Poughkeepsie, NY (rkm 121) and departed 

from the river on June 15 and 17 (18.5 oC – 18.9 oC) only to be detected in the coastal 

portion of the array near the mouth of the Delaware Bay with tag # DSU1084967 arriving 

on June 25 (22.7 oC) while tag # DSU1084976 arrived on July 12 (24.5 oC) where they 

maintained residency through the end of the reporting period 

Identification of Delaware River Atlantic Sturgeon Spawning Locations

2009 

Two Atlantic sturgeon (Transmitter #s DSU1052433 and DSU1052442) from our 

sampling were detected in the Delaware River, visual examination of gonads determined 

that both of these fish were males (Table 2). The haplotype for Atlantic sturgeon # 

DSU1052433 was A5, which is believed to be exclusive for the Delaware River 

(Grunwald et al. 2008). Atlantic sturgeon transmitter # DSU1052433 entered the river on 

May 14 (18.1 o

C) and remained until May 30 (20.4 oC) at which time it was detected in 

the Delaware Bay and subsequently in the coastal array (Figure 17). Atlantic sturgeon # 

DSU1052442 was identified having haplotype B, which occurs in both the Hudson and 
Delaware Rivers, entered the Delaware River on May 5 (16.2 o

C) and remained in the 

river until June 14 (22.3 o

C) when it was recorded migrating through the Delaware Bay 

and inhabiting the waters off the coast of DE (Figure 17). 

During the likely period of spawning in 2009, both telemetered Atlantic sturgeon 

utilized the area from Cherry Island (rkm 110) to Marcus Hook (rkm 130) for the 

majority of the time spent in the Delaware River although neither were recorded above 

rkm 130 (Figure 18). Monitoring of these individuals both actively and passively failed 

to produce any evidence of them moving into areas previously identified as likely 

spawning locations based on the presence of high freshwater flows and hard-bottom 

substrates (Sommerfield and Madsen 2003, Simpson 2008). Since these individuals 

failed to enter what was deemed likely spawning habitat, no directed sampling for eggs 

via egg mats took place. 

In addition to the two Atlantic sturgeons from our sampling, three telemetered 

Atlantic sturgeon from other studies were detected in the Delaware River (Figure 19). 

One male Atlantic sturgeon was previously tagged by # DSU1225 but the transmitter 

expired shortly after entering the Delaware River on May 11(17.6 o

C). The 2 additional 

Atlantic sturgeon were both telemetered in the Long Island Sound #’s CT290 and CT398. 

These Atlantic sturgeon were not thought to be mature as one was only 110cm FL in July 

2007 and the other 90cm FL in July of 2008. 

2010 

Four adult Atlantic sturgeon from our directed sampling efforts were detected in 

the Delaware River during 2010, two of these four were the same individuals that entered 

the Delaware River in 2009 (#’s DSU1052433 and DSU1052442) (Figure 20) while the 

remaining ones were telemetered earlier in the year (#’s DSU1084954 and DSU1084965) 
(Figure 20). Atlantic sturgeon # DSU1052433 (male, haplotype A5, Delaware specific, 

Grunwald et al. 2008) entered the river on April 27 (15.2 o

C) and departed on May 19 

(17.6 oC), Atlantic sturgeon # DSU1052442 (male, haplotype B, Hudson and Delaware, 

Grunwald et al. 2008) entered the river on May 7 (18.1 o

C) and departed on June 4 (23.8 

o

C); both sturgeon were detected in the same areas as in 2009 (rkm 110-130). Atlantic 

sturgeon # DSU1084954, which has haplotype A (range wide, Grunwald et al 2008), 

entered the river on April 16 (15.8 o

C) and departed the next day; visual inspection of the 

gonad revealed it to be a non-ripe female. Atlantic sturgeon # DSU1084965, which also 

exhibits haplotype A, entered the Delaware River on May 9 (18.0 o

C) and departed on 

June 6 (24.5 oC); visual inspection of the gonad revealed it to be a male. This Atlantic 

sturgeon occupied a lower portion of the Delaware River than did the other two 

telemetered males and predominantly used the area near New Castle, DE (rkm 100) 

although short (<20h) forays upriver to rkm 130 were recorded on three occasions. None 

of the four Atlantic sturgeon that were detected in the river during the spring of 2010 

were detected upstream of Marcus Hook, PA (rkm 130). Their movements were 

monitored via both passive and manual telemetry in an attempt to ascertain if they were 

moving into areas similar to that of known spawning habitat in other rivers (Gilbert 1989 

and Smith and Clugston 1997) or areas previously identified as potential spawning areas 

i.e. high freshwater flows and hard bottom (Sommerfield and Madson 2003, and Simpson 

2008). Utilizing the locations of the four telemetered Atlantic sturgeon in the Delaware 

River we attempted to collect fertilized eggs on cobble/gravel substrates in the area just 

below Marcus Hook, PA (rkm 120-126). We deployed a total of 83 eggs mats overnight 

for a total of 1,826 egg-mat/hours, but no Atlantic sturgeon eggs were collected (Figure 

18). 
In addition to the four telemetered Atlantic sturgeon from our sampling efforts, 

one telemetered Atlantic sturgeon (# CT308) of mature size (156cm FL in 2008) 

collected in Long Island Sound was detected in the Delaware River in the spring of 2010 

(Figure 22). This Atlantic sturgeon entered the lower portion of the Delaware River on 

April 9 (14.0 o

C) and remained in the river until May 5 (16.2 oC) when it rapidly departed 

and was detected again off the coast of MD, NJ and DE on May 11 and 12 (12.7 o

C). It 

then returned to the lower portion of the river on May 20 (17.6 o

C) were it remained until 

May 22 (18.6 oC) and then made a gradual upriver movement for three days, ultimately 

reaching rkm 165 near Philadelphia, PA. Following this upriver excursion there was a 

generalized downriver movement of CT308 until it exited the Delaware River on June 

1(23.0o

C). At the time this individual was in the Delaware River we were not privy to 

information on the sex or size and therefore directed little effort to tracking this Atlantic 

sturgeon. 

Discussion 

The Delaware River once contained the largest population of Atlantic sturgeon 

and may have exceeded other stocks by as much as ten-fold before being overexploited in 

the late 1800’s (Secor and Waldman 1999). The recent capture of young-of-the-year 

Atlantic sturgeon in the Delaware River (DNREC 2009), verifying an extant population, 

increases the emphasis for additional information on this imperiled population. Recently, 

telemetered adult Atlantic sturgeon were shown to utilize the Delaware River and express 

likely spawning behavior (Simpson 2008). Due to the general size of the Delaware 

River, high levels of commercial shipping, high tidal flows and flooding events 

documentation of spawning and the identification of spawning habitats through collection 

of fertilized eggs has been unsuccessful (Simpson 2008). Although confirmation of 
Atlantic sturgeon spawning did not occur during this project a great deal of additional 

data were collected on this subpopulation. In addition the acoustic transmitters deployed 

during the project have an estimated battery life in excess of six years, giving us an 

extended period of time to continue to gather information and further refine our estimates 

on the location of Atlantic sturgeon spawning sites in the Delaware River. With the 

recent proposed listing of Atlantic sturgeon under the ESA (NOAA and USFWS 2010) 

this information will prove to be very valuable to managers in their decision making 

process. 

 Eight telemetered Atlantic sturgeon entered the Delaware River in 2009 and 2010 

combined and five were of sufficient size and possibly reproductive condition to spawn. 

Even though use of areas deemed as appropriate spawning habitat (i.e. flowing freshwater 

and hard bottom) were not inhabited for extended periods of time there still was ample 

opportunity for spawning to occur. Previous research and sediment mapping identified 

areas of the river further upstream than telemetered sturgeon reached during this study as 

likely spawning habitats (Simpson 2008), but this previous work was conducted with 

limited sample sizes and may not account for interannual variability in river conditions 

(e.g. flow and temperature). Clear evidence of successful spawning was documented by 

the capture of young-of-year Atlantic sturgeon in 2009 (DNREC 2009), which could 

have taken place in the area inhabited by our telemetered Atlantic sturgeon during May 

and June. In waiting for our telemetered Atlantic sturgeon to make a characteristic 

spawning run further upstream we may have overlooked important areas near Marcus 

Hook. Towards the end of the spawning season in 2010 we deployed eggmats in the 

areas heavily utilized by the telemetered Atlantic sturgeon. Although these efforts were 

unsuccessful this may have been due to a lack of spawning in the presence of higher 
salinities in the area in 2010. Similar sampling for young-of-year Atlantic sturgeon was 

conducted in 2010 but none have been collected to date (DNREC pers. comm.) providing 

anecdotal evidence suggesting that Atlantic sturgeon may not have spawned successfully 

in the regions occupied by our telemetered individuals in 2010. Dovel and Berggren 

(1983) observed Atlantic sturgeon spawning in the lower reaches of the Hudson River 

during the beginning of the spawning season followed by a general shift upriver as the 

season progressed; a similar phenomenon to this may occur in the Delaware River and if 

so the timing and location of eggmat deployment may have been incorrect given the 

drought conditions encountered in 2010. 

Spawning intervals of Atlantic sturgeon in the mid-Atlantic region and the NY 

Bight have been estimated at every four years for females and every year for males (Bain 

et al. 2000), but this has not been verified conclusively. In the two years of this study we 

have documented two male Atlantic sturgeon utilizing potential spawning areas in 

consecutive years and with the six year battery life of the transmitters and continued 

deployment of acoustic receivers we should be able to document spawning intervals in 

both males and females in both the Hudson and the Delaware Rivers over the next five 

years. In addition, the longevity of transmitters coupled with information on the genetic 

composition of our samples should allow us to make strong inferences on the homing 

fidelity of Atlantic sturgeon to their natal river systems which has been identified as a 

priority research need (Grunwald et al. 2008). 

 Characterization of the Delaware River population of adult Atlantic sturgeon in 

the past has been difficult due to sampling constraints dictated by the large amount of 

shipping traffic occurring on the river (Simpson 2008). We have circumvented this 

obstacle by sampling for adult Atlantic sturgeon in coastal waters where tidal flows are 
moderate, limited vessel traffic, and there are large expanses of clean bottom which 

enables the deployment of large gillnets. These conditions coupled with the extensive 

knowledge of a commercial fisherman who once targeted Atlantic sturgeon proved 

successful in the collection of adults. Across both years of this study we were able to 

collect 101 adult Atlantic sturgeon of which the vast majority (n=90) received long lived 

acoustic transmitters. While the majority of telemetered Atlantic sturgeon did not enter 

the Delaware River on likely spawning runs we did note behaviors characteristic of 

spawning in a limited number of individuals. From these we have further refined our 

estimates of the likely regions of Atlantic sturgeon spawning in the Delaware River and, 

given the longevity of the transmitters, we are confident that additional Atlantic sturgeon 

will continue to mature over the transmitter lifespan providing insights in future years. 

This additional information combined with the knowledge of the genetic structure of the 

population off the coast of Delaware will allow for comparison among subpopulations of 

Atlantic sturgeon and could ultimately lead to the generation of drainage specific 

population estimates. 

The vast majority of the Atlantic sturgeon captured during this study represent 

individuals that do not have Delaware River specific haplotypes. These data may be 

indicative of the remnant nature of the Delaware River population of Atlantic sturgeon. 

On a whole it appears that the vast majority of Atlantic sturgeon both migrating through 

and residing in the region of the Delaware coast are from distant rivers which further 

exemplifies the need for proper management of these habitats for Atlantic sturgeon 

recovery efforts. 

 The majority of Atlantic sturgeon telemetered during our coastal sampling efforts 

did not enter the Delaware or Hudson Rivers; however, we were able to gain valuable 
information on their coastal movements and interbasin exchange rates through detection 

of transmitters in various arrays up and down the coast. Previous research has shown that 

Atlantic sturgeon aggregations shift up and down the coast as seasons change; however 

the majority of these data have come from short term telemetry and mark-recapture 

studies (Dovel and Berggren 1983, Hatin et al. 2002, Savoy and Pacileo 2003, and 

Simpson 2008) or bycatch data from either fishery dependent or independent research 

(Smith and Clugston 1997, Collins et al. 2000, Stein et al. 2004a, ASMFC 2007, Laney et 

al. 2007 and Dunton et al. 2010). While these studies provide a great deal of insight into 

the coastal movements and habitats used by Atlantic sturgeon their focus was not on 

continuous long-term movements of adults. Our findings combined with the recent 

conclusions of Erickson et al. (2010) emphasize the large scale movements of individual 

Atlantic sturgeon. 

Atlantic sturgeon utilized the coastal waters near the mouth of the Delaware Bay 

from the beginning of April through early December in both years of our study. This 

region is inhabited by Atlantic sturgeon from both the Delaware River and other 

subpopulations that are proposed to be listed as endangered under the recent proposed 

ESA ruling (NOAA and USFWS 2010). Observations of jumping Atlantic sturgeon in 

regions coinciding with heavy vessel traffic suggest the possibility of increased vessel 

strikes (Simpson and Fox 2009). Researchers at Delaware State University and DNREC 

have documented several Atlantic sturgeon mortalities in this area contributing to this 

body of evidence that harmful interactions are taking place. 

There are limited fishery independent measures on the habitat requirements of 

Atlantic sturgeon in the marine environment. The use of archival PSAT transmitters has 

enabled researchers to gain insights into the behavior of adult Atlantic sturgeon from the 
Hudson River (Erickson et al. 2010). While this study provided generalized movements 

the sample size was very small due to the inherent costs associated with satellite 

telemetry studies. As such, our findings on the timing of arrival and departure in addition 

to the generalized regions of coastal habitats utilized by Atlantic sturgeon should provide 

useful information to managers. Atlantic sturgeon have a very complex life history that 

utilizes a wide range of differing habitats. Our findings may enable managers to 

minimize and or mitigate negative interactions providing much needed information on 

the conservation and recovery for Atlantic sturgeon. Atlantic sturgeon are known to 

occupy near shore habitats when undertaking coastal migrations. These habitats are 

usually characterized by depth although regional differences appear to exist in the 

Northeast <60m and in the mid-Atlantic <25m (Stein et al. 2004a), and 9.1-21.3m in the 

mid-Atlantic during the winter (Laney et al. 2007). Erickson et al. (2010) also noted 

similar depths ranges of 10-50m as recorded by PSAT tags. In our approach we aimed to 

define habitat utilization not by depth but by distance from shore during migrations. This 

method may provide additional insights as depths utilized by Atlantic sturgeon seem to 

increase where the continental shelf is closer to shore (Stein et al. 2004a and Erickson et 

al. 2010). Additionally our approach may also prove beneficial to managers as most 

regulations are made from distance to shore measurements and not isobaths. 

Conclusions 

While we did not achieve our first objective of confirming the reproduction of 

Atlantic sturgeon, we were able to provide additional information on the likely location 

and timing of spawning in the Delaware River. Telemetered adult Atlantic sturgeon 

occupied substantial reaches of the lower Delaware River for extend periods of time in 

the spring of 2009 and 2010. Specifically they occupied the area from Cherry Island 
(rkm 110) to Marcus Hook (rkm 130) from early April to early June when water 

temperatures were between 15o

C and 24oC. No egg sampling took place during 2009 

when spawning was later confirmed by DNREC, in 2010 both egg sampling and gill 

netting for young-of-year efforts were unsuccessful and spawning could have potentially 

be limited by drought conditions. 

 Additionally, our combined approached of targeted sampling in marine waters 

with large mesh gillnets to collect adult Atlantic sturgeon coupled with the recent 

advances in acoustic telemetry provided insights into a life history stage that was once 

derived primarily from fishery dependent sources (Stein et al. 2004a and b, ASMFC 

2007, Dunton et al 2010). Genetic assignment to river of origin and telemetry data 

indicate that aggregations of Atlantic sturgeon in the Delaware coastal region consist of 

fish from multiple rivers of origin. The marine habitat near the mouth of the Delaware 

Bay is utilized by Atlantic sturgeon from a number of DPS units for prolonged periods of 

time 

Atlantic sturgeon occupy large expanses of the coastline when migrating north in 

the summer and the south in the winter. Our results indicate that the vast majority of 

Atlantic sturgeon utilize a relatively narrow strip of coastal waters (<7km offshore). The 

timing of occupancy showed limited interannual variability with the majority of Atlantic 

sturgeon arriving off the MD/DE coast between the first week in April with some fish 

making their way through the system by the end of June and some remaining in the 

system until late summer/early fall and the onset the southerly migration. 

These findings provide quantifiable estimates on timing of arrival, departure and 

occupation of Atlantic sturgeon in the Delaware River Estuary and coastal marine 

environment. Our findings can be used to provide guidance to resource managers on the 
optimal timing and location of potential anthropogenic impacts such as dredging, power 

generation, beach renourishment, commercial fishing, and traffic from recreational and 

commercial vessels to reduce and mitigate negative effects on Atlantic sturgeon 

populations. Previous efforts to define the spatial and temporal patterns of Atlantic 

sturgeon marine occupancy have been limited by their dependence on fisheries for 

sample collection and or low sample sizes. 

Atlantic sturgeon have been impacted by over-fishing and anthropogenic changes 

for over 130 years. Through this project we have provided new insights into the timing 

and location of Atlantic sturgeon spawning events as well as the first quantitative 

estimates on the timing of arrival, departure, and residency of marine habitats in 

Delaware coastal waters. We have also documented extensive migrations of Atlantic 

sturgeon telemetered in Delaware waters from Gray’s Reef, GA to the Gulf of Maine, a 

distance of over 1800km. Additionally we have provided key data on the genetic 

composition, rates of interbasin exchange and key habitat requirements for Atlantic 

sturgeon in the New York Bight DPS that will be hopefully assist managers in the 

recovery of this imperiled species. 

Acknowledgements 

We would like to thank the following individuals and organizations for their 

support with this project without their assistance this research effort would not have been 

possible. Kevin Wark, Endeavor Fisheries; Lori Brown, and Don Wujtewicz as well as 

the graduate students and staff, Delaware State University Aquatic Sciences; John Clark, 

Matt Fisher, and Craig Shirey, Delaware Natural Resources and Environmental Control; 

Hal Brundage, Environmental Research and Consulting, Inc; Tom Savoy, Connecticut 

Department of Environmental Protection; Dan Erickson, University of Miami, Pew 
Institute for Ocean Science; Ike Wirgin, New York University School of Medicine; Dave 

Secor, University of Maryland Chesapeake Biological Laboratory; The Atlantic 

Cooperative Telemetry Network; The United States Coast Guard; The United States Fish 

and Wildlife Service and last but not least the National Marine Fisheries Service 

Northeast Region Office of Protected Resources for providing additional funding for this 

project. 
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14:61–72. 
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Sommerfield, C.K., and J.A. Madsen. 2003. Sedimentological and geophysical survey of 

the upper Delaware Estuary. Final Report to the Delaware River Basin 

Commission. 

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and mortality on the continental shelf of the Northeast United States. North 

American Journal of Fisheries Management 24:171-183. 

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Van Eenennaam, J. P., S. I. Doroshov, G. P. Moberg, J. G. Watson, D.S. Moore, and J. 

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River and Estuary: 1877 – 1987. Masters Thesis, University of Delaware. 90p. 
Tables and Figures 

Table 1. Summary of fishing effort targeting adult Atlantic sturgeon along the Delaware 

coastline in spring 2009. (*due to weather gear did not fish adequately to constitute 

effort) 

Date Effort 

(100m/hour) 

Number of 

Sturgeon Captured 

Water Temperature 

(

o

C) 

3/18/2009 894.7 0 5.1 

3/19/2009 130.7 0 5.7 

3/25/2009 906.2 0 5.6 

3/26/2009 877.8 1 6.2 

3/27/2009 261.1 0 7.2 

4/4/2009 825.7 0 8.0 

4/5/2009 288.8 5 8.0 

4/7/2009 300.2 3 8.4 

4/8/2009 337.1 3 7.8 

4/9/2009 341.7 6 8.0 

4/10/2009 231.3 3 8.1 

4/13/2009 224.6 6 8.2 

4/17/2009 207.0 1 8.5 

4/18/2009 346.9 0 8.4 

4/19/2009 185.9 1 9.8 

4/21/2009 * 0 9.8 

4/23/2009 346.3 5 9.9 

4/24/2009 316.4 5 9.8 

4/25/2009 263.7 10 10.4 

4/26/2009 112.8 6 11.5 

 

Total 7398.9 55 - 

Mean 389.4 - 8.2 
Table 2. Individual Atlantic sturgeon capture histories, relevant biological statistics, and 

transmitter number for the 2009 sampling season. (* sex pending histological 

confirmation ** mortality) 

Date 

Fork 

Length 

(cm) 

Total 

Length 

(cm) 

Weight 

(kg) Sex PIT tag 

T-Bar 

Tag 

Transmitter 

ID 

4/5/2009 178 203 57 Male 3D9.257C65B1B5 44550 1052433 

4/5/2009 156 179 42 Unknown 3D9.257C63EF8F 44549 1052434 

4/7/2009 146 166 35 Male 3D9.257C6609FB 44501 1052435 

4/7/2009 156 181 45 Male* 3D9.257C652F8C 44503 1052438 

4/7/2009 153 181 38 Unknown 3D9.257C6564AC 44507 1052436 

4/8/2009 164 185 54 Female 3D9.257C63CC23 44504 1052439 

4/8/2009 142 162 39 Unknown 3D9.257C660F82 44505 1052440 

4/8/2009 166 180 50 Male 3D9.257C63D53E 44548 1052442 

4/9/2009 153 175 Male* 3D9.257C65B725 44546 1052443 

4/9/2009 157 181 48 Unknown 3D9.257C65B53F 44545 1052444 

4/9/2009 166 185 52 Male 3D9.257C65B593 44544 1052445 

4/9/2009 151 175 44 Male 3D9.257C656450 44543 1052447 

4/9/2009 157 178 48 Male* 3D9.257C65F9F1 44547 1052446 

4/9/2009 144 160 Male* 3D9.257C65465B 44593 1052448 

4/10/2009 145 164 35 Unknown 3D9.257C63EF51 44553 1052449 

4/10/2009 157 172 39 Male* 3D9.257C63C9E4 44552 1052450 

4/10/2009 186 203 69 Male 3D9.257C63D2AA 44554 1052415 

4/13/2009 154 168 43 Unknown 3D9.257C65F7E0 44591 1052421 

4/13/2009 150 179 45 Male 3D9.257C6552E0 44590 1052423 

4/13/2009 120 137 21 Unknown 3D9.257C660055 44589 1067081 

4/13/2009 158 179 32 Unknown 3D9.257C63DA5B 44588 1067082 

4/13/2009 173 205 64 Female 3D9.257C65289F 44587 1067084 

4/13/2009 160 177 42 Male 3D9.257C63E010 44586 1067085 

4/17/2009 138 158 31 Unknown 3D9.257C63D9E2 44585 1067115 

4/19/2009 152 188 53 Female 3D9.257C6553A9 44582 1067105 

4/23/2009 168 192 55 Female* 3D9.257C66084A 44556 1067094 

4/23/2009 161 180 51 Female* 3D9.257C652FDF 44561 1067095 

4/23/2009 210 239 93 Female 3D9.257C63CFCA 44562 1067093 

4/23/2009 170 191 44 Unknown 3D9.257C660567 44564 1067086 

4/23/2009 153 173 42 Unknown 3D9.257C65B5F5 44563 1067088 

4/24/2009 176 195 53 Unknown 3D9.257C6555DE 44565 1052416 

4/24/2009 158 185 43 Male 3D9.257C63CACF 44566 1052422 
Table 2. (continued). 

4/24/2009 156 178 40 Unknown 3D9.257C65AF7D 44567 1052428 

4/24/2009 178 202 49 Unknown 3D9.257C63C8EF 44568 1052451 

4/24/2009 161 188 41 Unknown 3D9.257C63E2B8 44569 1067083 

4/25/2009 153 172 36 Unknown 3D9.257C63E294 44581 1067087 

4/25/2009 168 194 57 Unknown 3D9.257C65ED81 44570 1067089 

4/25/2009 179 200 64 Unknown 3D9.257C63D3FE 44580 1067090 

4/25/2009 161 190 52 Female 3D9.257C661311 44571 1067091 

4/25/2009 200 220 78 Male 3D9.257C63D76E 44572 1067097 

4/25/2009 173 194 60 Female 3D9.257C65BE43 44573 1067099 

4/25/2009 149 168 32 Unknown 3D9.257C6513A0 44575 1067101 

4/25/2009 142 161 32 Unknown 3D9.257C660738 44574 1067102 

4/25/2009 155 173 41 Unknown 3D9.257C65294E 44576 1067103 

4/25/2009 163 190 55 Male 3D9.257C65B31B 44577 1067107 

4/26/2009 169 185 47 Unknown 3D9.257C65C2F5 44578 1067109 

4/26/2009 183 204 69 Male 3D9.257C63F033 44579 1067111 

4/26/2009 164 186 53 Unknown 3D9.257C6555AA 44507 1067110 

4/26/2009 131 150 21 Unknown 3D9.257C65F4BE 44506 1067113 

4/26/2009 188 210 74 Male 3D9.257C63C6E3 44508 1067112 

4/26/2009 160 183 57 Unknown 3D9.257C63D389 44509 1067116 

3/26/2009 199 219 56 Female n/a n/a ** 

4/5/2009 174 198 42 Male n/a n/a ** 

4/5/2009 226 248 86 Female n/a n/a ** 

4/5/2009 153 169 36 Male 470C35535F n/a ** 

Min 120 137 21 10 Females 

Max 226 248 93 20 Males 

Mean 163 185 49 
Table 3. Summary of fishing effort targeting adult Atlantic sturgeon along the Delaware 

coastline in spring 2010. 

Date Effort 

(100m/hour)

Number of 

Sturgeon Captured

Water 

Temperature (

o

C)

3/28/2010 221.0 0 7.0

4/1/2010 318.5 1 8.0

4/2/2010 306.0 1 8.8

4/3/2010 303.3 1 8.7

4/4/2010 301.8 3 8.4

4/5/2010 232.6 1 10.1

4/6/2010 249.9 0 9.4

4/9/2010 320.0 1 8.3

4/10/2010 292.0 0 9.3

4/12/2010 377.3 4 10.6

4/13/2010 276.1 0 10.4

4/15/2010 326.4 6 9.6

4/16/2010 304.8 1 11.0

4/20/2010 353.3 6 10.6

4/21/2010 301.4 8 11.2

4/22/2010 166.1 13 11.1

4/23/2010 301.8 8 11.9

Total 4952.3 54

Mean 291.3 9.7
Table 4. Individual Atlantic sturgeon capture histories, relevant biological statistics, and 

transmitter number for the 2010 sampling season. (*sex pending histological 

confirmation) 

Date 

Fork 

Length 

(cm) 

Total 

Length 

(cm) 

Weight 

(kg) Sex PIT tag 

T-Bar 

Tag 

Transmitter 

ID 

4/1/2010 156 180 42 Unknown 3D9. 1C2D0460A1 44633 1084948 

4/2/2010 168 186 48 Female * 3D9. 257C660637 1084949 

4/3/2010 170 199 50 Unknown 3D9. 257C6561DE 44511 1084950 

4/4/2010 130 150 21 Unknown 3D9. 257C65E711 44518 n/a 

4/4/2010 155 179 36 Unknown 3D9. 1C2D04E30F 45159 1084951 

4/4/2010 174 195 55 Male 3D9. 257C63CC86 44519 1084952 

4/5/2010 175 199 57 Male 3D9. 257C65F658 44520 1084953 

4/9/2010 154 180 41 Female * 3D9. 257C63C5D1 44521 1084954 

4/12/2010 158 181 43 Male * 3D9. 257C63DE01 44522 1084955 

4/12/2010 184 208 58 Male * 3D9. 257C655107 44540 1084956 

4/12/2010 186 73 Unknown 3D9. 257C65EDDA 44538 1084957 

4/12/2010 196 223 79 Female 3D9. 257C660F9B 44537 1084958 

4/15/2010 138 162 31 Unknown 3D9. 257C65F746 44523 1084959 

4/15/2010 155 183 42 Female 3D9. 257C65B13B 44526 1084960 

4/15/2010 165 191 52 Male 3D9. 257C63D90E 44527 1084961 

4/15/2010 170 190 56 Unknown 3D9. 257C63E05E 44528 1084962 

4/15/2010 167 194 50 Unknown 3D9. 257C655CE0 46701 1084963 

4/15/2010 121 141 19 Unknown 3D9. 1C2D04DDD5 46702 n/a 

4/16/2010 185 207 62 Unknown 3D9. 257C655F6E 46703 1084964 

4/20/2010 171 193 53 Male 3D9. 257C63C599 46704 1084965 

4/20/2010 174 201 57 Female 3D9. 257C656045 46705 1084966 

4/20/2010 230 255 >110 Female 3D9. 257C653218 46706 1084967 

4/20/2010 178 215 86 Female 3D9. 257C655E36 46707 1084968 

4/20/2010 170 185 50 Unknown 3D9. 257C65F9EF 46708 1084969 

4/20/2010 173 192 52 Female * 3D9. 257C65DE96 46709 1084970 

4/21/2010 177 192 51 Unknown 3D9. 257C652A4A 46710 1084971 

4/21/2010 122 138 22 Unknown 3D9. 257C656345 46711 n/a 

4/21/2010 177 203 50 Unknown 3D9. 257C6369B6 46712 1084972 

4/21/2010 157 177 48 Unknown 3D9. 257C6538A2 46713 1084973 

4/21/2010 225 252 >110 Female 3D9. 257C63E4E8 46714 1084974 

4/21/2010 180 202 55 Female 3D9. 257C63E8A4 46715 1084975 

4/21/2010 161 180 52 Male 3D9. 257C652C31 46716 1084976 

4/21/2010 174 200 50 Female 3D9. 257C65EE36 46717 1084977 

4/22/2010 159 180 49 Female 3D9. 257C6527B3 46718 1084978 

4/22/2010 173 203 51 Female 3D9. 257C63DE5D 46719 1084979 

4/22/2010 206 230 84 Female 3D9. 257C65C1D0 46720 1084980 

4/22/2010 168 188 48 Female 3D9. 257C65B538 46721 1084981 

4/22/2010 173 198 60 Unknown 3D9. 257C65AEDB 46722 1084982 

4/22/2010 138 155 26 Unknown 3D9. 257C653597 46723 n/a 

4/22/2010 139 160 29 Unknown 45745E0135 46724 n/a 

4/22/2010 119 137 22 Unknown 3D9. 257C6557A2 46725 n/a 

4/22/2010 132 151 25 Unknown 3D9. 257C65BE07 46726 n/a 

4/22/2010 132 154 29 Unknown 3D9. 257C63C8D9 46727 n/a 

4/22/2010 166 190 62 Female 3D9. 257C6531A3 46728 1084983 

4/22/2010 151 174 41 Female 3D9. 257C65FC83 46729 1084984 
Table 4. (continued) 

4/22/2010 188 218 62 Female 3D9. 257C63C866 46730 1084985 

4/23/2010 171 189 48 Unknown 3D9. 257C63C7BE 46733 n/a 

4/23/2010 149 166 39 Female 3D9. 257C63C9B2 46735 1084986 

4/23/2010 153 172 42 Unknown 3D9. 257C65C73A 46736 n/a 

4/23/2010 160 184 45 Unknown 3D9. 257C65D62A 46737 n/a 

4/23/2010 148 167 44 Unknown 3D9. 257C64C5DA 46738 n/a 

4/23/2010 124 144 23 Unknown 3D9. 257C64D428 46739 n/a 

4/23/2010 141 153 32 Unknown 3D9. 257C651CC7 46740 n/a 

4/23/2010 131 148 27 Unknown 3D9. 257C63E3BC 46742 n/a 

Min 119 137 19 19 Females 

Max 230 255 >110 7 Males 

Mean 162.9 184.8 46.7 

Table 5. Frequency of Atlantic sturgeon genetic haplotypes of samples collected during 

gillnetting effort in 2009 and 2010 off the coast of Delaware. 

 Haplotypes Number 

Entire Range A 24

Hudson River B1, B2, C4, C5 4

Hudson/Delaware River B 32

Delaware River A5 2

Delware to southern extent C, N, N1 21

Hudson to southern extent D 4

Georgia P8 1

Edisto River P1 1

New Haplotype origin unknown A6 1

 Table 6: Summary of Atlantic sturgeon captured off the DE coast, detections by location 

strata for the 2009 sampling season. 

Number of Detections 

(Number of Atlantic Sturgeon) 

Strata 2009 2010 

Delaware River 8,268 (2) 5,009 (7) 

Delaware Bay 15,635 (39) 27,258 (65) 

Coastal 10,971 (47) 43,286 (77) 

Hudson River 10,054 (7) 10,212 (21) 

 

Total 44,928 (48) 85,765 (80) 

 
Figure 1. Location of acoustic receivers in the Delaware River, Delaware Bay, and 

Coastal waters of DE, MD and NJ with the coastal sampling location. 
Figure 2. Location of acoustic receivers in the Hudson River and New York Harbor. 
Figure 3. Atlantic sturgeon sampling locations using anchored gill nets off the DE coast 

in 2010 with temporary acoustic receivers locations to assist in sampling effort. 
Figure 4. Atlantic sturgeon sampling locations using anchored gill nets along the DE 

coast in 2009. 
Figure 5. Catch per unit of effort of Atlantic sturgeon and temperature for sampling 

effort in 2009. 

Figure 6. Catch per unit of effort of Atlantic sturgeon and temperature for sampling 

effort in 2010. 
Figure 7. Number of Atlantic sturgeon, captured of the DE coasts, representing each 

haplotype grouping for 2009 and 2010. 

Figure 8. Relocations of individual Atlantic sturgeon telemetered during coastal 

sampling in 2009 by region in 2009. 

DE = Array in Delaware, HR = Hudson River, and LIS = Long Island Sound. 
Figure 9. Relocations of individual Atlantic sturgeon telemetered for additional research 

by region in 2009. 

DE = Array in Delaware, HR = Hudson River, and LIS = Long Island Sound. 
Figure 10. Relocations of individual Atlantic sturgeon telemetered during coastal 

sampling in 2010 by region in 2010. 

DE = Array in Delaware, HR = Hudson River, and LIS = Long Island Sound. 
Figure 11. Relocations of individual Atlantic sturgeon telemetered during coastal 

sampling in 2009 by region in 2010. 

DE = Array in Delaware, HR = Hudson River, and LIS = Long Island Sound 
Figure 12. Location of Atlantic sturgeon relocations along the East Coast of the United 

States for 2009 and 2010. 
Figure 13. Number of telemetered Atlantic sturgeon detected in the coastal portion of the 

Delaware passive array by date. 

Figure 14. Relocations of individual Atlantic sturgeon telemetered for additional 

research by region in 2010. 

DE = Array in Delaware, HR = Hudson River, and LIS = Long Island Sound. 
Figure 15. Number of telemetered Atlantic sturgeon detected by each passive acoustic 

receiver in the receiver gate during the spring of 2010. 
Figure 16. Marine concentration area utilized during the summers of 2009 and 2010 with 

the box outlining area of high concentration near Cape Henlopen, DE. 
Figure 17. Relocations of individual Atlantic sturgeon telemetered during coastal 

sampling in 2009 in the Delaware River Estuary by region in 2009. 
Figure 18. Location of acoustic receivers in the Delaware River with eggmatt sampling 

locations in 2010. 
Figure 19. Relocations of individual Atlantic sturgeon telemetered for additional 

research, in the Delaware River Estuary by region in 2009. 

 
Figure 20. Relocations of individual Atlantic sturgeon telemetered during coastal 

sampling in 2009, in the Delaware River Estuary by region in 2010. 
Figure 21. Relocations of individual Atlantic sturgeon telemetered during coastal 

sampling in 2010, in the Delaware River Estuary by region in 2010. 
Figure 22. Relocations of individual Atlantic sturgeon telemetered for additional 

research, in the Delaware River Estuary by region in 2009