Jeff Mercer, "Following the Quahog Through Time and Space," Baird Symposium
Upcoming SlideShare
Loading in...5
×
 

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

on

  • 533 views

Jeff Mercer, Principal Biologist, R.I. Department of Environmental Management

Jeff Mercer, Principal Biologist, R.I. Department of Environmental Management

Topic: Maximizing Harvest

Statistics

Views

Total Views
533
Views on SlideShare
533
Embed Views
0

Actions

Likes
0
Downloads
5
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

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

  • Following the Quahog Through Time and Space Jeff Mercer RI DEM, Principal Biologist November 14, 2013
  • 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%
  • Why Quahogs? Shellfish Catch from 1865  (Goode and Associates, 1887) Oviatt et al (2003)
  • Why Quahogs?
  • Why Quahogs? 30,000,000 lbs
  • Why Quahogs?
  • Why Quahogs?
  • Why Quahogs?
  • Why Quahogs? • ~50% of nitrogen in quahog  derived from sewerage  (Oczkowski et al, 2008)
  • Why Quahogs? (Oczkowski et al, 2008) • ~50% of nitrogen in quahog  derived from sewerage  •More tolerant to hypoxia than  predators = Predation refuge (Altieri, 2008)
  • 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
  • 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
  • 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
  • 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
  • Size Structured Stock Assessment Model 160 Landings 140 # of Quahogs (millions) 120 100 80 60 40 20 0 Year Gibson, 2010
  • Size Structured Stock Assessment Model 600 Abundance Landings # of Quahogs (millions) 500 400 300 200 100 0 Year Gibson, 2010
  • 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
  • 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
  • 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
  • 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
  • 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
  • How Many Quahogs do We Need? Kraeuter et al, 2005
  • How Many Quahogs do We Need? Kraeuter et al, 2005
  • 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
  • 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
  • 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
  • Spatial Distribution of Quahogs • Not corrected for  dredge efficiency • High densities  correspond to  productive fishing  grounds • Shallow areas poorly  assessed • Closed Areas highest  densities
  • Larval Export from Closed Areas • ~100 million eggs/m2 • Larval Duration 8‐12 days • Large potential  reproductive output
  • 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)
  • 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
  • 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
  • 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 
  • Larval Counts UpperBay Lost 38.2% 
  • Larval Counts Larval Counts Open Prohibited  Lost  43.8%  Lost 28.6% 
  • Greenwich Cove  Transplants
  • Greenwich  Cove Potowomut Sanctuary High  Banks
  • Dispersal From Donor & Transplant Sites Greenwich Cove  Prohibited High Banks Management Area  Approved
  • Comparison of Transplant Sites Potowomut Spawner Sanctuary  Approved‐Closed High Banks Management Area  Approved
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • Fished Protected Habitat Area51% of Studies  49% of Studies  Fisheries Yield  Fisheries Yield  Higher with  Higher with  MPAs Traditional  Management F P Habitat Area
  • Fished Protected Habitat Area F P Habitat Area Adapted from Gaylord, et al., 2005