Delaware State University, Department of Agriculture and Natural Resources, Dover, DE

1. Passive acoustic monitoring of fishes in the mid-Atlantic: providing the where and when for managers Dewayne Fox Delaware State University, Department of Agriculture and Natural Resources, Dover, DE dfox@desu.edu

2. Outline • Atlantic sturgeon • Phil Simpson • Sandtiger shark • Johnny Moore • Conclusions

3. Sturgeons • Fossil records back 85 MYBP • 25 species worldwide with 9 species in North America • Anadromous or restricted to freshwater • Body with 5 rows of scutes • Nearly all species are endangered or threatened

4. Sturgeon Harvesting • Vulnerability due to life history traits • “Black gold” • Ex-vessel prices >$50/lb • Retail >$200/ounce • Delayed maturation and long life spans (>100 years) • Limited prospects for natural recovery in many populations

5. Atlantic sturgeon(Acipenser oxyrinchus oxyrinchus) • Anadromous • Range • St. Lawrence River, Canada to St. Johns River, FL • Long lived • Large (4.3m and 350 kg) • 60 years • Late-maturing • Males 10-12 years • Females 13-20 years • Spawning Requirements • Hard substrate with high flow rates • Fresh water

6. Atlantic Sturgeon Migration Spring

7. Atlantic Sturgeon Migration ? ? ? ? Summer

8. Atlantic Sturgeon Migration Fall

9. Atlantic Sturgeon Migration Winter

10. 100+ years of Atlantic Sturgeon Management in the Delaware River • “The roe was considered worthless except as bait to catch eels, and perch or to feed the hogs” • Cobb, J. N. 1900 • “Under the present conditions it is only a question of a few years until the day of the sturgeon fishery will have collapsed” • Tower, W. S. 1908

11. Atlantic sturgeon Fishery Management: Modern Challenges • ASMFC issued Fishery Management Plan 1990 • Fishing moratorium (1998) • Status review (1998) • Did not warrant protection • Harvest moratorium issued • Status review (Feb 2007) • 3 of 5 Distinct Population Segments (DPSs) recommended for threatened status

12. Distinct Population Segments (DPS) • Threatened • Carolina • Chesapeake Bay • New York Bight • Not listed • Gulf of Maine • South Atlantic Status Review 2007

13. Caviar, NJ History of Delaware River Atlantic Sturgeon Fishery • Leni Lenape Indians “celebrated the arrival of the sturgeon with an orgy of fishing” • 1869 Penn’s Grove • “Albany beef” • 1889 Caviar, NJ • 400 harvesters • 12-15 railroad cars daily • Up to 5 railroad cars of caviar daily

14. Delaware River Atlantic Sturgeon Fishery • Historic Abundance estimated at 180K Females in 1890 • Average weight • female 118 kg • male 29.5 kg Golden Years Stock Collapse Landings (million lbs) Recruitment Failure Year Secor and Waldman 1999

15. Delaware River • Largest freshwater port complex in world • Over 3000 deep draft vessels/year • 42 million gallons crude oil moved daily

16. Juvenile Habitat Utilization • Estuarine/marine residency • GROWTH • May occupy non-natal estuaries during spring/summer

17. Objectives • Characterize habitat use during period of estuarine residency • Substrate • Depth • Environmental parameters • Identify migratory patterns • Immigration/emigration

18. Methods: Collection/Telemetry • Gill nets • Varying mesh sizes (15–30.5 cm) • Anchored vs. drift • Telemetry • Internal transmitters • Previously established surgical protocol

19. Telemetry Equipment • Vemco ltd. • Sturgeon – 2 year tags • Battery life- 10 years • VR-2 passive receivers • Data sharing • Delaware Estuary • shortnose sturgeon • striped bass • horseshoe crab • sandbar and sand tiger sharks • Atlantic Cooperative Telemetry (ACT) Network • 28 research groups ME-FL

20. VEMCO

21. VEMCO

22. VEMCO

23. Telemetry Array • 2005 (n=38) • 2006 (n=55) • 2007 (n=56) • 2008 (n=63)

24. Based on M. Moser design Telemetry Equipment

25. Active Tracking • Focus on juvenile habitat • Range based on C.A. Shirey (1997) telemetry study • Methods • Weekly monitoring of riverine section • Listen at 1 km intervals

26. 2005-2007 Juvenile Sturgeon Passive Relocations (n=279,167) 2005 (n = 15) well defined concentration areas (Shirey 1997) 2006 (n = 12) concentration zones less defined 2007 (n = 10*) increased heterogeneity in habitat occupation *based on returns, no new fish tagged

27. Atlantic sturgeon movement 2005-2007

28. Polychaete bloom 2007 Juvenile Atlantic sturgeon • Representative data? • Immigration and emigration patterns • Movement driven by prey resources? • Polychaete or “mud” worms (ECS 1993) • Johnson et al. 1997 • Haley 1998

29. Habitat Selection: DNREC Delaware Bay Benthic Mapping Program Images courtesy of Bart Wilson

30. Habitat Utilization: Substrate • Delaware state benthic mapping program dataset • Independent sediment analysis • 90% correlation macro-format classification • Individual Chi-square test • Collectively, habitat selection is occurring for gravel/hard-bottom substrate • X2 (308.91) > test statistic (149.45), df = 100

31. Habitat Utilization: Depth • Data Source: NOAA Bathymetric Maps • Commonly relocated in/along navigation channel • Anchorage areas

32. Habitat Utilization: Depth • Deep water habitat selection • Collectively, selection for 8 – 16m depths • X2 (238.4) > test statistic (149.5), df = 100

33. Conclusions for Delaware River Atlantic sturgeon • Juvenile habitat utilization • Depth and substrate selection • Deep water secondary channel/anchorage areas • Coarse grain materials • Migratory Patterns • March 19 immigration • November 24 emigration • Migratory patterns indicate marine overwintering habitat • Recent discovery (Feb 14, 2008) of juvenile mortality within estuary ( ≈river kilometer 80) • Wide use of riverine habitat during estuarine residency

34. Deepwater habitat selection outside main traffic area • Crown Landing LNG Proposal • Delaware Deepening Project • Critical habitat designation • Gravel/hard-bottom substrate, depth preferences, prey availability, physiochemical properties • Migratory patterns indicate marine overwintering habitat • March 19 return – Dec 17 exit • Recent discovery (Feb 14, 2008) of juvenile mortality within estuary ( ≈river kilometer 80) • Boat Strikes Conclusions

35. Site fidelity and patterns of habitat use of sandtiger sharks (Carcharias taurus) in Delaware Bay

39. Life History • Females • Mature at 220-230 cm TL • 9-10 years of age • Males • Mature at 190 cm TL • 6-7 years • Maximum Size ≈ 4m • Size at birth ≈ 1m • Forage on fishes including other sharks/rays, horseshoe crabs, and mollusks • Thought to be primarily nocturnal

40. Reproduction • 2 year reproductive cycle • 9-12 month gestation • Litter size of 2 • embryophagy • 1 female every other year assuming 1:1 sex ratio • 0.5 female offspring per year • Among lowest reproductive output for any known shark or ray

41. Management 1993 - NMFS FMP large coastal species 1997 - NMFS prohibited species category 1997 - petitioned for ESA listing 2007 Stock Assessment and Status Review (?)

42. Sand Tiger Shark Migration Mating February to May

43. Sand Tiger Shark Migration Pupping December to March Pregnant females do not migrate?

44. YOY?? Age 1+ Sand Tiger Shark Migration Salinities too low? Spring Migration Pregnant females do not migrate?

45. YOY?? Age 1+ Sand Tiger Shark Migration Fall Migration

46. Methods • Long line • 366 m length • Baited circle hooks (16/0) • 2 hour soak times • Directed sampling and random NMFS Apex predator surveys • All sand tigers were measured, sexed, fitted with an external tag, and had genetic samples collected

47. Tagging • Implanted with long-life (800 days) standard acoustic transmitters (V16-6H) • 2006 n = 4 • 2007 n = 15 • Implanted with long-life (800 days) depth sensing transmitters (V16-6H) • 2007 n = 10

48. Results • Total of 29 sand tigers were implanted with acoustic transmitters • 2006 n = 4 • 2007 n = 25 • 17 female • 12 male