Jeff Mercer, "Following the Quahog Through Time and Space," Baird Symposium

1. Following the Quahog Through Time and Space Jeff Mercer RI DEM, Principal Biologist November 14, 2013

2. Quahogs by The Numbers 39.1 Million 6.96 Million $5.15 million 534 Clams Pounds Dollars Fishermen CHERRY 3% 2012 Landings 1. 2. 3. 4. 5. Squid Lobster Sea Scallop Summer Flounder Quahog $19 Million $12 Million $9 Million $7 Million $5 Million CHOWDER 10% TOP NECK 23% LITTLE NECK 64%

3. Why Quahogs? Shellfish Catch from 1865 (Goode and Associates, 1887) Oviatt et al (2003)

4. Why Quahogs?

5. Why Quahogs? 30,000,000 lbs

6. Why Quahogs?

7. Why Quahogs?

8. Why Quahogs?

9. Why Quahogs? • ~50% of nitrogen in quahog derived from sewerage (Oczkowski et al, 2008)

10. Why Quahogs? (Oczkowski et al, 2008) • ~50% of nitrogen in quahog derived from sewerage •More tolerant to hypoxia than predators = Predation refuge (Altieri, 2008)

11. Why Quahogs? • ~50% of nitrogen in quahog derived from sewerage •More tolerant to hypoxia than predators = Predation refuge •Closure areas due to pollution de facto marine reserves Density 8‐20 X Greater than Avg

12. Spatial Management of Shellfish In RI • • • • Prohibited = 122.6 km2 Conditional = 56 km2 Seasonal = 4.1 km2 Approved = 215.1 km2 • Management = 67.8km2 • Est. Fishable Area ~ 125km2

13. Impact of Pollution Closures 3000 # of Licenses Meat Weight (MT) Landings (MT) & Licenses (#) 2500 2000 1500 1000 500 0 1945 1950 1955 1960 1965 1970 1975 1980 Year 1985 1990 1995 2000 2005 2010 * NMFS Landings Data

14. Impact of Pollution Closures 3000 # of Licenses Meat Weight (MT) Landings (MT) & Licenses (#) 2500 2000 1500 1000 500 0 1945 1950 1955 1960 1965 1970 1975 1980 Year 1985 1990 1995 2000 2005 2010 * NMFS Landings Data

15. Size Structured Stock Assessment Model 160 Landings 140 # of Quahogs (millions) 120 100 80 60 40 20 0 Year Gibson, 2010

16. Size Structured Stock Assessment Model 600 Abundance Landings # of Quahogs (millions) 500 400 300 200 100 0 Year Gibson, 2010

17. Size Structured Stock Assessment Model 600 1984 Abundance in Millions (t) 500 1985 1986 400 1987 1988 1989 300 1991 1990 1992 1994 2010 2011 2008 2002 2001 2006 2012 2005 1997 2007 2009 1999 2003 1998 2000 1996 2004 200 1993 1995 100 0 0.00 0.10 0.20 0.30 0.40 F Rate (t-1) 0.50 0.60 0.70

20. How Many Quahogs do We Need? Logarithmic Stock‐Recruitment Models Great South Bay, NY Polynomial Density Dependence 0.75 Adults/m2 = Recruitment Failure Kraeuter et al, 2005

21. How Many Quahogs do We Need? 600 Abundance Landings Recruitment Failure # of Quahogs (millions) 500 400 0.75 Adults/m2 X 125km2 Fishable Area 300 200 100 0 Year

22. How Many Quahogs do We Need? Kraeuter et al, 2005

23. How Many Quahogs do We Need? Kraeuter et al, 2005

24. How Many Quahogs do We Need? 600 Abundance Landings Reduced Recruitment Landings (millions) 500 1.5 Adults/m2 X 125km2 Fishable Area 400 300 200 100 0 Year

25. Uneven Spatial Distributions of Quahogs ma Coastal Ponds 0.8% Conditional A Greenwich Not Identified 0.7% Management Areas 0.9% Conditional B Sakonnet 0.6% Mt Hope Bay 0.3% Block Island 0.0% ma ma East Passage East Passage 11.9% West Passage West Passage 25.9% Greenwich Bay 14.4% ma Conditional B 20.9% Conditional A 23.6% • No info on Closed Waters • Tagging Areas are Large

26. RI DEM Quahog Dredge Survey 1993‐2013 • Use hydraulic dredge to sample adult populations • Stratified Random Sampling Design • 2368 tows of 30 m • 26,000+ clams

27. Spatial Distribution of Quahogs • Not corrected for dredge efficiency • High densities correspond to productive fishing grounds • Shallow areas poorly assessed • Closed Areas highest densities

28. Larval Export from Closed Areas • ~100 million eggs/m2 • Larval Duration 8‐12 days • Large potential reproductive output

29. Larval Export from Closed Areas • ~100 million eggs/m2 • Larval Duration 8‐12 days • Large potential reproductive output Too Dense? Crowding may lead to poor condition and low reproductive output Marroquin‐Mora & Rice (2008) CI = dry soft tissue wt X 1000/ (total wt ‐ shell wt)

30. Where are the Larvae? •Sampled 60 sites, once/week for 6 weeks •Used qPCR to enumerate larvae •Providence River, Warren River, Western Greenwich Bay have highest densities •2 major spawning events; mid‐June and early to mid July •Only a snapshot in time – Where will they end up? Average Larval Densities at Surface

31. Tracking Larvae from Source to Settlement • Larvae released randomly over 30 day period • Released in top 2 meters • Passive for 11 days • Swim towards bottom for 24 hours – randomness added • Site Specific Settlement – OFF LTRANS

32. Source – Sink Dynamics • Assess larval dispersal throughout the Bay • Release larvae in proportion to adult densities • Working towards developing a matrix model including: – Adult population demographics – Fecundity index – Spatially varying mortality rates – Connectivity matrix

33. Larval Counts UpperBay Lost 38.2%

34. Larval Counts Larval Counts Open Prohibited Lost 43.8% Lost 28.6%

35. Greenwich Cove Transplants

36. Greenwich Cove Potowomut Sanctuary High Banks

37. Dispersal From Donor & Transplant Sites Greenwich Cove Prohibited High Banks Management Area Approved

38. Comparison of Transplant Sites Potowomut Spawner Sanctuary Approved‐Closed High Banks Management Area Approved

39. Reproductive Condition of Quahogs: Efficacy of Transplants Preliminary Results (2012)  Significantly lower mean CI in closed sites (p=0.0001)  Lag in CI of quahogs in closed sites (Spring and Fall)  Mark‐Recapture experiment (ongoing) ‐ Tag 1600 quahogs from G.C. ‐ Transplant to Potowomut S.S. Matt Griffin RWU/URI

40. Soft Shell Clams‐ A Cautionary Tale 1400 Shell Weight (lbs X 1000) 1200 1000 800 600 400 200 0 2003 2004 2005 2006 2007 2008 Year 2009 2010 2011 2012 2013

41. Soft Shell Clams‐ A Cautionary Tale 1400 Shell Weight (lbs X 1000) 1200 1000 800 600 400 200 0 2003 2004 2005 2006 2007 2008 Year 2009 2010 2011 2012 2013

42. Summary & Recommendations • Fishing rates and quahog populations in fished waters have been relatively stable since 2004 • Areas prohibited to fishing act as sanctuaries where biomass accumulates‐ May contribute as much as half of the effective reproductive potential of the Bay • Need to carefully assess impact of opening additional areas to harvest to the bay‐wide population • Need more monitoring of populations in closed areas – density and reproductive health • Continue development of spatially explicit population model that will allow for better assessment of management strategies • Need better understanding of post–set processes and mortality

43. Acknowledgements Dave Ullman Candace Oviatt Chris Kincaid Tatiana Rynearson Christelle Balt Mark Gibson Dennis Erkan & everyone who assisted with DEM Dredge survey Funding Sources: The Nature Conservancy Global Marine Initiative Student Research Award URI GSO Alumni Scholarship Rhode Island DEM

44. Number of Active Licenses for Quahogs‐ Grouped by License Type 1400 MPURP PEL CFL SFO65 STUD MPURP Active PEL Active CFL Active SFO65 Active STUD Active 1200 # of Licenses 1000 800 600 400 200 0 2003 2004 2005 2006 2007 2008 Year 2009 2010 2011 2012

45. Licenses and Landings 3000 # of Licenses Meat Weight (MT) 12 Unemployment Rate 10 2000 8 1500 6 1000 4 500 2 0 1945 Unemployment Rate (%) Landings (MT) & Licenses (#) 2500 0 1950 1955 1960 1965 1970 1975 1980 Year 1985 1990 1995 2000 2005 2010 * NMFS Landings Data

46. Fished Protected Habitat Area51% of Studies 49% of Studies Fisheries Yield Fisheries Yield Higher with Higher with MPAs Traditional Management F P Habitat Area

47. Fished Protected Habitat Area F P Habitat Area Adapted from Gaylord, et al., 2005

Jeff Mercer, "Following the Quahog Through Time and Space," Baird Symposium

riseagrant

Jeff Mercer, "Following the Quahog Through Time and Space," Baird Symposium