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 19901Introduction

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). A tlantic sturgeon historically occupied all major river systems along the Atlantic coas t between Canada and Florida, with the Delaware River historically supporting the largest population (Secor and Waldman 1999). The U.S. commercial fishery for Atlant ic sturgeon had its ro ots 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 tri butaries within state jurisdiction (Vroom and Lanning 1895). In 1990, the A tlantic States Marine Fi sheries 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 Clugst on 1997). Following a petition to list the Atlantic sturgeon under the Endange red Species Act, a status review was conducted in 1998 eventually determining the species did not warrant additional protection under the ESA (NOAA and USFW S 1998) , although the ASMFC imposed a coastwide moratorium during the same year (ASMFC 1998). In 2005, the NMFS

initiated another status review of the Atla ntic sturgeon based on the conclusions of a 2003 NMFS/USFWS joint committee. The status revi ew team released their recommendations in February 2007 which stated three of the fi ve distinct population segments of Atlantic sturgeon be listed as threatened under the ES A, including the New Yo rk Bight DistinctPopulation 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 popul ation segments under the ESA with the New York Bight and th ree 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 resu lting from channel modifications in the Delaware River Estuary (Albert 1988). These navigation projects resulted in removal of

over 1.5 x 10 8 m 3 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 regi mes may impact the recovery of New York Bight DPS Atlantic sturgeon. Changing weathe r patterns may ultimately lead to an uncoupling of moderately increasing temperatur es and spring freshets that have been linked to spawning in the closely re lated Gulf of Mexico sturgeon ( A. o. desotoi ) (Fox et al. 2000). In August 2009, the first successful spaw ning 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 n eed for better information on the location and nature of current spawning ha bitat in the Delaware River Estuary. The most recent research on the location of spawning areas fo r Atlantic sturgeon was conducted almost a century ago and was derived from fishery depend ent data collected before the collapse of the fishery in the 1890’s (Borodin 1925).The recent topic of DPS has been he avily debated by Atlantic sturgeon researchers (Grunwald et al. 2008). The 2007 Status Review recommends dividing the US populations into 5 DPSs based on all avai lable data. This recommendation was based on a lower sample size, fewer populations and nuclear DNA as oppos ed to mitochondrial DNA examined in 2008 by Grunwald et al. Grun wald et al. (2008) further question the validity of DPSs entirely due to the current reproductive isolati on of river specific Atlantic sturgeon populations. The grouping of multiple river systems into a single DPS may limit understanding and recovery of some populations (Grunwal d et al. 2008). As a result of the underlying need for informati on of stock structure, resource managers require further clarification of homing fide lity 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 move d 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 move ments 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 moveme nt patterns the sample size was small and entirely from the Hudson River populati on. Movement data has been collected from the bycatch of Atlantic sturgeon during sc ientific research efforts and commercialfisheries, but knowledge of th e Atlantic sturgeon’s seasona l and long term movements, habitat utilization, distribution, and migrat ory 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 At lantic waters for foraging after leaving their spawning rivers (Dovel and Berggren 1983). An examination of fisheries dependent bycatch data off the nor theastern coast of the US indicates that Atlantic sturgeon primarily occupy shallow in shore areas of the c ontinental 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, Vi rginia to Hatteras, NC at depths usually less than 18m (Laney et al. 2007). Coastal f eatures including inlets and the mouths of bays are thought to hold higher concentrations of Atlantic st urgeon (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 gr owing body of evidence to suggest that adult Atlantic sturgeon utilize the lower por tions of the Delaware Estuary for prolonged periods of time during th e summer months (Simpson 2008, D. Fox, unpublished data). Atlantic sturgeon are highly migrator y and have been known to move great distances. Atlantic sturgeon cap tured and tagged in CT waters were recaptured from MD to NH, with the direction of travel being nor th in the summer and south in the fall and winter (Savoy and Pacillo 2003). More recen t 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 fi ndings follow the general patterns outlined inprevious studies on Atlantic sturgeon (Dovel 1979, Smith 1985, Shirey 1995). In addition to these migrations juvenile stur geon 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 sout h (Stein et al. 2004b). Bycatch events are highest in the fall, winter a nd spring when sturgeon are thought to be moving coastally to and from spawning grounds and lowest in th e summer months (Stein et al. 2004b) when Atlantic sturgeon are believed to enter estuarine and rive rine 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 move ment 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 Dela ware River and begin to gather data (e.g., location of spawning grounds, spawning inte rvals, genetic characteristics of the population and ultimately, population size estim ates) on this subpopulation and 2: Estimate interbasin exchange rates between the Delaware and the Hudson rivers through the use of compatible telemetr y systems in both rivers.Materials and Methods Study Area Adult Atlantic sturgeon sampling took pl ace in marine waters 3 to 15km off the coast of DE in the region of the DE/MD borde r (Figure 1). An array of passive acoustic receivers (VEMCO VR-2 and VR2W) were pla ced in the waters Delaware River Estuary, off the coast of MD, DE, NJ, and the Hudson Ri ver (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 de fined as the region extending

seaward from the C&D Canal to a line draw n from Cape Henlopen, DE to Cape May, NJ (RKM 0) (Figure 1). The Coastal portion includes the area seaw ard 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 usi ng gill nets and techniques similar to those developed in the Atlantic sturgeon coas tal intercept fishery before its closure in 1998. Monofilament gill nets consisting of te n panels (91.0m x 6.1m) strung together were fished as one long net. We employed me sh 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 hour s 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 pi ngers (Fumunda, specs (freq. 10 kHz, power 132dB) at the beginning of the net and at the j unction 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 compos ition 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 poi nts of each net deployment were recorded with a GPS and depth was recorded w ith 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, mainta ining ambient temperature, salinity and dissolved oxygen levels. All individuals were measured (F L and TL) to the closest cm and weight was measured to the closest kg us ing a hanging scale. At lantic sturgeon were scanned for the presence of a passive integrated transponde r (PIT) tag, using an AVID®

Power Tracker VIII or Biomark® FST2001FT PIT tag reader, and monitored for the presence of an existing VEMCO Ltd. acous tic 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 fi sh at the base of the dorsal fin (Fuller et al. 2008). A tissue sample was taken from the cau dal fin and placed in 95% ethanol for genetic analysis. A USFWS plastic-t-bar tag wa s inserted on the left side of the fish at the base of the dorsal fin following establis hed protocol (Damon-Ra ndal et al. 2010). Implantation protocols developed by F ox 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 assistan ce of a sling to reduce stress and injury toboth researchers and the Atlant ic sturgeon; the sling consist of a 1.3 m x 2 m coated canvas strung between two 3 cm x 2.2 m w ooden 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 equilib rium and signs of slowed respiration, individuals were placed in a sling, ventral side up, while th eir 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 in to the body cavity. When po ssible 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 co mpound, in an attempt to minimize rejection rates (Boyd Kynard, US GS, 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 inf ection. Oxytetracycline (OTC, 200mg/mL) was administered as a prophylactic antibiotic at a dose of 1.0 mL per 20kg body weight near the base of the dorsal fin, with a half-dos e anterior to the PIT tag and a half-dose posterior of the PIT tag. Atlantic sturge on 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 transferre d to a 1,100 l recovery tank and monitored. After regaining equilibrium, i ndividuals were released near the location of capture by gently lowering the fish, usi ng the sling, into the water.Telemetry The existing passive listeni ng array in the Delaware River Estuary, and off the coast of MD, DE and NJ (Figure 1) was ma intained 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 batte ry (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 downl oaded on an approximately monthly basis. The detection range of these receivers depends on site lo cation and weather conditions although ranges of 0.5km - 2.8km are comm only encountered (Simpson 2008). In 2010 we deployed eight passive acousti c receivers approximately 2 km south of the area where gillnetting occurred in addi tion 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 determ ine the pathways utilized by previously

telemetered Atlantic st urgeon (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 mo re detailed monitoring approach utilizing passive and active telemetry was employed unt il 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 ex ist (i.e. flowing freshw ater and hard bottom habitats) (Gilbert 1989 and Smith and Clugst on 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 abra sive surface suitable for the adhesion of sturgeon eggs. We measured depth, te mperature, oxygen, substrate composition, and conductivity at three loca tions 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 Mexi co sturgeon (Fox et al. 2000).

Genetics Tissue samples collected from all At lantic sturgeon captured during marine

collections were sent to Ti m 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 equi pment in other river systems and along the eastern seaboard we were able to expand the detection areas of telemetered adult Atlanticsturgeon outside of our primary array. Additi onally, 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 (Figur e 4). In total we exerted 7,398.9 100m/hours of sampling effort during th e 2009 sampling season. As a result of

these efforts we landed 55 Atlantic stur geon on 13 days (Table 1). Sampling was initiated when water temperat ures were approximately 5 o C although we had limited success until temperatures reached 8 o C. In the first year of sampling Atlan tic 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 pr ior to the cessation of overnight sampling events. Following these mortalities we cha nged our sampling strategy and no additional mortalities occurred during the remainder of the study pe riod. All 51 sturgeon captured and released alive received long-lived (>6 year) ultrasoni c transmitters.2010 During the 2010 sampling season we in itiated our sampling when water temperatures reached 7°C as we saw limited su ccess 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 collec ted 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 larg e enough (>1.3m FL) to have reached sexual maturity. Thirty-nine of the 50 adult Atlant ic sturgeon captured r eceived long-lived (>6 year) ultrasonic transmitters, the remaini ng 15 received only PIT tags and USFWS t-bar

tags. Gillnetting success was limited in bot h 2009 and 2010 during the first several sampling events. As water temperatures increa sed 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 a nd sea turtles with rising water temperatures increases the probability of interactions.

Genetics We have received the haplotype distri butions for collected Atlantic sturgeon

based on mitochondrial DNA and we are aw aiting the results of the nuclear DNA microsatellites assignments.The genetic makeup of our collections pr ovide 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 (Grunw ald 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 highe st number of the samples collected (38), followed by haplotypes from the entire range of the species (A) (24), and then haplotypes representing th e 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 H udson 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 collaborati on with other research ers. Sixteen adult Atlantic sturgeon from other projects were in corporated into this research, 3 telemetered by Delaware State University in 2006 and 2007, seven telemetered by the CT Department of Environmental Protection in Long Is land 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 we re 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-s hore coastal environment (Figure 1). The deployment of acoustic receivers in the H udson 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 wa s deployed in the Hudson River to document inter-basin exchange rates (Figure 2). These receivers were

maintained in the Hudson River until N ovember 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 pa rtitioned the array in to 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 (Fi gure 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 receiv ers (VEMCO VR-2 and VR-2W) deployed in the Delaware River Estuary and near shore coastal environment in 2009 were maintained throughout the winter months; how ever, several receivers did have to be removed due to threats of icing. In additi on to the redeployment of receivers removed due to the threat of icing, 12 acoustic receivers were a dded to new locations in the Delaware Bay and Coastal portions of the arra y in the spring of 2010 (Figure 1). In the

Hudson River 13 acoustic receiv ers were redeployed on May 11 th and 12 th to document inter-basin exchange rates. Receiver totals for the four st rata 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 th e 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 si x 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 fa r 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) detect ed 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 o C), utilized a limited reach of the Atlantic Ocean near the mouth of the Delaware Bay until September 20 (20.7 o C) and was not detected again until Marc h 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 o C). This individual then was detected in similar portions of the Dela ware Bay and the Atlantic Ocean near the coast of Delaware as in 2009, where it rema ined through the end of the reporting period (Figure8 and 11). On May 16, 2010 Atlantic sturgeon DS U1084977 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 ra nge of Atlantic sturgeon (Gru nwald et al. 2008). This sturgeon was detected in Delaware Bay on Ap ril 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 st urgeon were detected in the Long Island Sound, three of which were detected in 2009 and 2010, and 14 detected off the coast ofNorth 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 a nd the coastal waters of North Carolina. Telemetered Atlantic sturgeon used Long Isla nd Sound primarily in the summer and fall, detected by the receivers from June 5 to Oct ober 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 n ear 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 fi rst 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 Rive r, Long Island Sound or continuing on to the Gulf of Maine during its spring migra tion north (Figure 8, 9, 10 and 11). In the spring of 2009 teleme tered Atlantic sturgeon a rrived off the DE and MD coastlines from April 5 to June 5 (7.0 o C to 16.6 o C) (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 o C) (median departure date May 23(15.4 o C)). In 2010 Atlantic sturgeon arrived in the coastal portion of the ar ray from April 2 to June 23 (7.7 o C to 22.3 o C) (median arrival date May 2 (12.9 o C)) and departed from April 7 to June 25 (9.6 o C to 22.7 o C) (median departure date May 28 (15.2 o C)). Atlantic sturgeon that migrated through the coastal array pres umably heading northward spent between 1- 64 days (median 22 days) in the array in 2009 and from 2-68 days (median 27 days) in2010 (Figure 14). Only returning telemetere d Atlantic sturgeon were used in the

calculation of arrival da tes to avoid biases associated wi th in season tagging efforts. Atlantic sturgeon that resided in the array dur ing the summer months were not used in the calculation of departure times as these individuals did not depa rt 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 A tlantic sturgeon detections

occurred within 7km of shore and 85% of A tlantic sturgeon were detected within the jurisdictional boundary of state wa ters (Figure 15). The rece ivers located at 14 and 16km from shore did not detect any Atlantic stur geon and the receivers lo cated 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 resi dency in the area near the mouth of the Delaware Bay. Sixteen telemetered Atlant ic sturgeon were documented using eight receivers just outside the southern edge of the mouth of the Delaware Bay in 2009 (Figure 16). These limited move ments occurred from July 1 (21.7 o C) to September 12 (21.4 o C) and these resident Atlan tic sturgeon inhabited the coas tal 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 aggregat ions 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 en trance to Delaware Bay in th e Atlantic Ocean is a highly channelized, very deep (>30m) area with very high tidal flows, gravel substrate andpolyhaline waters. Residency times for te lemetered 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 enti re range of the population (Haplotype A), eight from th e 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 fr om the Hudson River to the s outhern extent of the range (Haplotype D) (Grunwald et al. 2008). In 2009, summer resident Atlantic stur geon 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 o C) (median date November 3(16.1 o C)); the last recorded telemetered Atlantic sturgeon in th e coastal array occurr ed on December 1 (13.1

o C) with a median date of departure being October 16 (17.9 o C). Atlantic sturgeon which arrived after the departure of summer residents spent little time in th e coastal array in the fall of 2009; of the 11 telemetered Atlantic st urgeon 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 ther e is a possibility that some telemetered Atlantic sturgeon did enter and exit the river pr ior to deployment. On July 14-16, ten days prior todeployment of receivers in the Hudson Rive r, we manually tracked from Catskill, NY (rkm 179) to the mouth of the river. Th is was done by stopping and listening with a manual acoustic hydrophone every 1.5km to document the presence of telemetered Atlantic sturgeon in the rive r. In doing so we documented ten telemetered Atlantic sturgeon occupying the river, six from our De laware collections prior in the spring and

four that were telemetered in the Hudson River in 2008. Eleven telemetered Atlantic sturgeon were detected on the r eceiver array in the Hudson River in 2009, seven from our sampling efforts, two telemetered in the Hudson River in 2008, and two that were telemete red 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 r eceivers. Telemetered Atlantic sturgeon did

continue to utilize the H udson River until October 12 (18.6 o C), with eight of the remaining telemetered 11 Atlantic st urgeon leaving between September 13 (20.6 o C) 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; f our 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 o C - 23.6 o C)). Departure from the river began as early as May 11 (11.0 o C) and continued throughout spring and summer. Due to logistical cons traints the upper six ac oustic receivers on the river have not been downloaded since June 28, 2010 but are still bei ng maintained in the river. This coupled with the fact that telemetered Atlantic sturgeon continue to occupythe river as of the end of this reporting pe riod 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. Th ese two Atlantic sturgeon (# DSU1084967 and # DSU 1084974) were the largest in dividuals captured during collec tion efforts. They were collected on April 20 and 21 and both were gravid fema les. Both Atlantic sturgeon remained near the mouth of the Delaware Bay until May 22 and 23, 2010 (14.6 o C – 15.1

o C) when they made a directed migrati on north entering the Hudson River on May 29 (16.2 o C). They were detected as far north as Poughkeepsie, NY (rkm 121) and departed from the river on June 15 and 17 (18.5 o C – 18.9 o C) 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 o C) while tag # DSU1084976 arrived on July 12 (24.5 o C) 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 Rive r, 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). A tlantic sturgeon transmitter # DSU1052433 entered the river on May 14 (18.1 o C) and remained until May 30 (20.4 o C) at which time it was detected in the Delaware Bay and subsequently in the coas tal array (Figure 17). Atlantic sturgeon #

DSU1052442 was identified havi ng haplotype B, which occu rs in both the Hudson andDelaware 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 migr ating 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 (rk m 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 indi viduals both actively and passively failed to produce any evidence of th em 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 spaw ning 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 dete cted in the Delaware River (Figure 19). One male Atlantic sturgeon was previous ly 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 dire cted sampling efforts were detected in the Delaware River during 2010, two of these four were the same indi viduals that entered the Delaware River in 2009 (#’s DSU 1052433 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) entere d the river on April 27 (15.2 o C) and departed on May 19 (17.6 o C), Atlantic sturgeon # DSU1052442 (male, haplotype B, Hudson and Delaware, Grunwald et al. 2008) entere d 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 ha s 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 o C); visual inspection of the gonad reveal ed 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 de tected 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 sp awning habitat in othe r rivers (Gilbert 1989 and Smith and Clugston 1997) or areas previous ly identified as pot ential spawning areas i.e. high freshwater flows and hard bottom (Sommerfield and Madson 2003, and Simpson 2008). Utilizing the locations of the four telemetered Atlan tic sturgeon in the Delaware River we attempted to collect fertilized eggs on cobble/gravel substr ates in the area just below Marcus Hook, PA (rkm 120-126). We depl oyed a total of 83 eggs mats overnight for a total of 1,826 egg-mat/hours, but no Atlant ic sturgeon eggs were collected (Figure 18).In addition to the four telemetered Atla ntic sturgeon from our sampling efforts, one telemetered Atlantic sturgeon (# CT 308) 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 por tion of the Delaware River on April 9 (14.0 o C) and remained in th e river until May 5 (16.2 o C) 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 por tion of the river on May 20 (17.6 o C) were it remained until May 22 (18.6 o C) and then made a gradual upriver movement for three days, ultimately reaching rkm 165 near Philadelphia, PA. Fo llowing this upriver excursion there was a generalized downriver movement of CT308 unt il it exited the Delaware River on June 1(23.0 o C). At the time this indi vidual was in the Delaware River we were not privy to

information on the sex or size and therefore direct ed 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 informa tion on this imperiled population. Recently, telemetered adult Atlantic sturgeon were show n to utilize the Delaware River and express likely spawning behavior (Simpson 2008). Du e to the general size of the Delaware River, high levels of commercial ship ping, high tidal flows and flooding events documentation of spawning and the identifica tion of spawning habitats through collection of fertilized eggs has been unsuccessful (Simpson 2008). Although confirmation ofAtlantic 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 stur geon under the ESA (NOAA and USFWS 2010) this information will prove to be very va luable to managers in their decision making

process. Eight telemetered Atlantic sturgeon en tered the Delaware River in 2009 and 2010

combined and five were of sufficient size and possibly reproductiv e condition to spawn. Even though use of areas deemed as appropria te spawning habitat (i.e . flowing freshwater and hard bottom) were not inhabited for ex tended periods of time there still was ample opportunity for spawning to occur. Previous research and sedime nt mapping identified areas of the river further upstream than tele metered 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 eviden ce of successful spawning was documented by the capture of young-of-year Atlantic st urgeon 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 A tlantic 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. Alt hough these efforts were unsuccessful this may have been due to a lack of spawning in the presence of highersalinities in the area in 2 010. Similar sampling for young-of-year Atlantic sturgeon was

conducted in 2010 but none have been collected to date (DNREC pe rs. comm.) providing anecdotal evidence suggesting that Atlantic sturgeon may not have spawned successfully in the regions occupied by our telemetere d 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 sh ift 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 depl oyment 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 year s for females and every year for males (Bain et al. 2000), but this has not b een verified conclusively. In the two years of this study we

have documented two male Atlantic stur geon utilizing potential spawning areas in consecutive years and with the six year ba ttery 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 longev ity of transmitters coupled w ith 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 At lantic sturgeon in the past has been difficult due to sampling constraints dictated by the large amount of shipping traffic occurring on the river (Sim pson 2008). We have circumvented this obstacle by sampling for adult Atlantic sturge on in coastal waters where tidal flows aremoderate, limited vessel traffic, and there are large expanses of clean bottom which enables the deployment of larg e gillnets. These conditions coupled with the extensive knowledge of a commercial fisherman who once targeted Atlantic sturgeon proved

successful in the collection of adults. Acro ss both years of this st udy we were able to collect 101 adult Atlantic sturgeon of which th e 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 lif espan providing insights in future years.

This additional information combined with th e knowledge of the gene tic 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 st urgeon captured during this study represent

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

indicative of the remnant nature of the Dela ware 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 fo r Atlantic sturgeon recovery efforts. The majority of Atlantic sturgeon tele metered during our coastal sampling efforts did not enter the Delaware or Hudson Rivers; however, we were able to gain valuableinformation on their coastal movements and in terbasin 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 studi es provide a great de al 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 scal e movements of individual Atlantic sturgeon. Atlantic sturgeon utilized the coastal wate rs 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 lis ted as endangered under the recent proposed ESA ruling (NOAA and USFWS 2010). Observa tions of jumping Atlantic sturgeon in regions coinciding with heavy vessel traffic suggest the possi bility of increased vessel strikes (Simpson and Fox 2009). Researchers at Delaware State Un iversity and DNREC have documented several Atlantic sturgeon mort alities in this area contributing to this body of evidence that harmful interactions are taking place. There are limited fishery independent m easures 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 theHudson 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 th e 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 st urgeon have a very complex life history that utilizes a wide range of di ffering 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 regi onal 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 di stance from shore during migrations. This method may provide additional insights as dept hs utilized by Atlantic sturgeon seem to

increase where the continental shelf is closer to shore (Ste in 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 s hore measurements and not isobaths.

Conclusions While we did not achieve our first obj ective of confirming the reproduction of Atlantic sturgeon, we were able to provide additional informati on on the likely location and timing of spawning in the Delaware Rive r. Telemetered adult Atlantic sturgeon occupied substantial reaches of the lower De laware 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 15 o C and 24 o C. 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 coup led with the recent advances in acoustic telemetry provided insigh ts into a life histor y 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 rela tively narrow strip of coastal waters (<7km offshore). The timing of occupancy showed limited interannual va riability with the ma jority 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 an d the onset the southerly migration. These findings provide quantifiable estimat es on timing of arrival, departure and occupation of Atlantic sturgeon in the De laware River Estuary and coastal marine environment. Our findings can be used to provide guidance to resource managers on theoptimal timing and location of potential anth ropogenic impacts such as dredging, power generation, beach renourishment, commercial fi shing, 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 lim ited 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, departur e, and residency of marine habitats in

Delaware coastal waters. We have also doc umented 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 a nd 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 i ndividuals 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 St ate University Aquatic Sciences; John Clark, Matt Fisher, and Craig Shirey, Delaware Na tural Resources and Environmental Control; Hal Brundage, Environmental Research a nd Consulting, Inc; Tom Savoy, Connecticut Department of Environmental Protection; Dan Erickson, University of Miami, PewInstitute for Ocean Science; Ike Wirgin, New York University School of Medicine; Dave Secor, University of Maryland Chesapeak e Biological Laboratory; The Atlantic Cooperative Telemetry Network; The United Stat es 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.Literature Cited Albert, R.C. 1988. The historical context of water quality management for the Delaware River Estuary. Estuaries 11:99-107. ASMFC (Atlantic States Marine Fisherie s Commission). 1998. Amendment 1 to the Interstate Fishery Management Plan for Atlantic sturgeon. Fishery Management Report No. 31 of the ASMFC. 43 pp. ASMFC (Atlantic States Marine Fisheries Commission). 2007. Estimation of Atlantic sturgeon bycatch in coastal Atlantic comme rcial fisheries of New England and the Mid-Atlantic. Special Report to the ASMFC Atlantic Sturgeon Management Board. 95 pp. Bain, M., N. Haley, D. Peterson, J.R. Waldman, and K. Arend. 2000. Harvest and habitats of Atlantic sturgeon Acipenser oxyrinchus Mitchill, 1815 in the Hudson River estuary: lessons for sturgeon cons ervation. 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Robbins, T. Savoy, and A. Spe lls. 2010. Atlantic sturgeon research techniques. NOAA Technical Memorandum NMFS-NE-215: 64 pp DNREC. 2009. DNREC Fish and Wildlife staff discover evidence of sturgeon spawning in Delaware River. News from the Department of Natural Resources and Environmental Control. 39:374 Di Lorenzo, J.L, P. Huang, M.L. Thatcher, a nd T.O. Najarian. 1993. Effects of historic dredging activities and water diversio ns on the tidal regime and salinity distribution of the Delaware Estuary. Final Report for the Delaware Estuary Program Preliminary Characterization a nd Research Topic 5: Long-term River Flow and Circulation Studies. 124p.Dovel, W. L. 1979. The biology and management of shortnose and A tlantic sturgeon of the Hudson River. N.Y. Dept. of Environ. Conserv. Rep. No. AF59-R-2. 54 p. Dovel, W.L., and T.J. Berggren. 1983. Atla ntic Sturgeon of the Hudson Estuary, New York. New York Fish and Game Journal 30(2):140-172. Dunton, K.J., A. Jordaan, K.A. Mckow n, D.O. Conover and M.G. Frisk. 2010. Abundance of and distribution of Atlantic sturgeon (Acipenser oxyrinchus) within the Northwest Atlantic Ocean, determined fr om five fishery-independent surveys. Fisheries Bulletin, 108: 450-465. Erickson, D.L., A. Kahnle, M.J. Millard, E.A. Mora, G. Bryja, A. Higgs, J. Mohler, M. DuFour, G. Kenney, J. Sweka, and E.K. Pik itch. In Press. Use of pop-up satellite archival tags to identify oceanic-migrato ry patterns for adult Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus Mitchell, 1815. Journal of Applied Ichthyology. Erickson, D.L., and J.E. Hightower. 2007. Oceanic distribution and behavior of green sturgeon. American Fisher ies Society Symposium. 56:197-211. Fox, D., Hightower, J.E., and Paruaka, F. 2000. Gulf sturgeon spawning migration and habitat in the Choctawhatchee River system , Alabama-Florida. Transactions of the American Fisheries Society, 129: 811-826. Gilbert, C. R. 1989. Atlantic and shortnos e sturgeons. 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Endangered and threatened wildlife and plants; proposed listing determinations for three dis tinct population segments of Atlantic sturgeon in the northeast region. Federal Re gister 75(193) 61872 - 61902. Ryder, J.A. 1888. The sturgeons and sturgeon industries of the eastern coast of the United States, with an account of e xperiments bearing upon sturgeon culture. Bulletin of U.S. Fish Commission 8:231-329. Saffron, I. 2002. Caviar. Broadw ay Books, New York, NY. Savoy, T. and D. Pacileo. 2003. Movements and important habitats of subadult Atlantic sturgeon in Connecticut waters. Transacti ons of the American Fisheries Society 132:1-8. Secor, D.H. and J.R. Waldman. 1999. Hist orical abundance of Delaware Bay Atlantic sturgeon and potential rate of recovery. American Fisheries Society Symposium, 23: 203-216. Shirey, C. A. 1995. Delaware River Atlant ic sturgeon tag and recapture program. Delaware Division of Fish and Wildlife, Annual Report, Dover. Shirey, C.A. 1997. Abundance of sub-adult Atla ntic sturgeon and areas of concentration within the lower Delaware River. Final Report, Grant No. NA66FG0326, Delaware Division of Fish and Wildlife, Dover, DE. Simpson, P.C. 2008. Movements and habitat use of Delaware River Atlantic Sturgeon. Masters Thesis. Delaware State Un iversity, Dover, Delaware. 137pp. Simpson, P. C., and D. A. Fox. 2009. Contempor ary understanding of the Delaware River impacted aquatic ecosystem. American Fisheries Society Symposium 69: 867- Atlantic sturgeon: su rvival in a highly 870. Smith, T. I. J. 1985. The fishery, biology a nd management of Atlantic sturgeon, Acipenser oxyrhynchu s, in North America. Envi ronmental Biology of Fishes 14:61–72.Smith, T.I.J., and J.P. Clugston. 1997. Status and management of Atlantic sturgeon, Acipenser oxyrinchus , in North America. Enviro nmental Biology of Fishes 48:335-346. Sommerfield, C.K., and J.A. Madsen. 2003. Sedi mentological and geophysical survey of the upper Delaware Estuary. Final Re port to the Delaware River Basin Commission. Stein, A.B., K.D. Friedland, and M. Sutherla nd. 2004a. Atlantic sturgeon marine bycatch and mortality on the continental shelf of the Northeast United States. North American Journal of Fish eries Management 24:171-183. Stein, A.B., K.D. Friedland, and M. Su therland. 2004b. Atlantic sturgeon marine distribution and habitat us e along the northeastern coast of the United States. Transactions of the American Fisheries Society 133:527-537. Van Eenennaam, J. P., S. I. Doroshov, G. P. Moberg, J. G. Watson, D.S. Moore, and J. Linares. 1996. Reproductive conditio ns of the Atlantic sturgeon ( Acipenser oxyrinchus ) in the Hudson River

. Estuaries 19(4):769-777. Vroom, G.D.W., and W.M. Lanning. 1895. General statutes of New Jersey. 1561pp. Walsh, D.R. 2004. Anthropogenic influences on the morphology of the tidal Delaware River and Estuary: 1877 – 1987. Masters Thesis, University of Delaware. 90p.Tables and Figures

Table 1. Summary of fishing effort targeting ad ult 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 - 8.2Table 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 1052422Table 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 49Table 3. Summary of fishing effort targeting ad ult Atlantic sturgeon along the Delaware coastline in spring 2010. 

### Date Effort (100m/hour) Number of Sturgeon Captured Water Tem p erature ( 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 9.7Table 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 1084984Table 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 geneti c 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 stur geon 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 w ith 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 loca tions to assist in sampling effort.Figure 4. Atlantic sturgeon sampling locati ons using anchored gill nets along the DE coast in 2009.Figure 5. Catch per unit of effort of Atla ntic sturgeon and temperature for sampling effort in 2009.

Figure 6. Catch per unit of effort of Atla ntic sturgeon and temperature for sampling effort in 2010.Figure 7. Number of Atlantic sturgeon, captu red of the DE coasts, representing each haplotype grouping for 2009 and 2010.

Figure 8. Relocations of individual Atla ntic 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 Atla ntic sturgeon teleme tered 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 Atla ntic sturgeon teleme tered during coastal sampling in 2009 by region in 2010. DE = Array in Delaware, HR = Hudson River, and LIS = Long Island SoundFigure 12. Location of Atlantic sturgeon relocations along the East Coast of the United States for 2009 and 2010.Figure 13. Number of telemetere d Atlantic sturgeon detected in the coastal portion of the Delaware passive array by date.

Figure 14. Relocations of individual Atla ntic 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 ga te during the spring of 2010.Figure 16. Marine concentrati on area utilized during the summers of 2009 and 2010 with the box outlining area of high concen tration near Cape Henlopen, DE.Figure 17. Relocations of individual Atla ntic sturgeon teleme tered 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 Atla ntic sturgeon telemetered for additional research, in the Delaware Ri ver Estuary by region in 2009.Figure 20. Relocations of individual Atla ntic sturgeon teleme tered during coastal sampling in 2009, in the Delaware River Estuary by region in 2010.Figure 21. Relocations of individual Atla ntic sturgeon teleme tered during coastal sampling in 2010, in the Delaware River Estuary by region in 2010.Figure 22. Relocations of individual Atla ntic sturgeon telemetered for additional research, in the Delaware Ri ver Estuary by region in 2009