The Lay of the Land: Understanding Quahog Management in Rhode Island

The Lay of the Land:

Understanding Quahog Management in Rhode Island

Jeff Mercer

RI DEM, Principal Biologist

May 19, 2014

39.1 Million Clams 6.96 Million Pounds $5.15 million Dollars 534 Fishermen

Quahogs by The Numbers

2012 Landings 1. Squid $19 Million 2. Lobster $12 Million 3. Sea Scallop $9 Million 4. Summer Flounder $7 Million 5. Quahog $5 Million

CHERRY3%

CHOWDER10%

LITTLE NECK64%

TOP NECK23%

• Management Goals

– What do we hope to accomplish through management?

• Management Tools

– What are the specific ways which we manage the resource and fishery?

• Assessment Methods

– How do we go about assessing existing strategies and potential modifications to management?

Outline

Management Philosophy

The marine fishery resources belonging to, allocated to, and of interest to Rhode Island need to be preserved and protected, at healthy, sustainable levels-

– Because of their ecological value, and

– Because they are renewable natural resources that provide food, recreation, income, employment, and other economic, social, and cultural benefits.

• Maintain the health of the State’s marine ecosystem

• In accordance with sustainable harvest levels, manage harvest in ways that

– Make full and effective use of available harvest opportunities, while minimizing discards, ecological impacts, habitat degradation, and other wasteful practices

– Balance the interests of different user groups and stakeholders

Management Goals

• Recreational Harvesters – Provide fair, open, and equitable access and harvest opportunities

with certain preferences to residents of the State

• Commercial Industry – Maintain an economically strong viable and diverse industry

– Support the business interest of fishermen and economic interest of the industry

– Support safe fishing operations

– Support enhanced marketing opportunities

• Prospective Fishermen – Provide meaningful access opportunities without unduly impacting

the interests of those currently engaged in the industry

• General Public – Maintain the health of the State’s marine ecosystem

– Provide a stable supply of safe, fresh, locally caught seafood

Management Goals

– Minimum Size

– Harvest Methods

– Licensing

– Daily Catch Limits

– Area Based Management

• Limited Access Time

• Reduced Daily Limits

• Rotational Harvest

• Spawner Sanctuaries

– Transplants

– Harvesting and Handling Requirements (OWR &DOH)

Management Tools

– Fishery Dependent

• Landings Data - SAFIS

• Catch Per Unit Effort (CPUE)

– Fishery Independent

• Dredge Survey

• Other field surveys

– Life History Studies

• Age and Growth

• Maturity schedule

• Fecundity

• Natural Mortality

Models

Bay-Wide Population Modeling

Area-Specific Depletion Modeling

Computer Simulations

Assessment Methods

Harvesting and Handling – OWR & DOH

Density 8-20 X Greater than Avg

• Pollution closures act as de facto marine reserves

• 50% of nitrogen in quahog has origin from waste water

• More tolerant to hypoxia than predators = predation refuge

Harvesting and Handling – OWR & DOH

• Pollution closures act as de facto marine reserves

• 50% of nitrogen in quahog has origin from waste water

• More tolerant to hypoxia than predators = predation refuge

0

500

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20

00

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20

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Lan

din

gs (

MT)

& L

ice

nse

s (#

)

# of Licenses Meat Weight (MT)

Minimum Size

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60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Sh

ell

Wid

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mm

)

Age (yrs)

Legal Size

Growth Curve

Sexual Maturity

*1987 moved from 1.5” length to 1” width

0

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3000

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Lan

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MT)

& L

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s (#

)

Year


* NMFS Landings Data

Harvest Methods

31,000,000 lbs

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2500

3000

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Lan

din

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MT)

& L

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)

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Harvest Methods

31,000,000 lbs =

3,500 Elephants

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1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

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MT)

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)

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Harvest Methods

TITLE 20 § 20-6-7 Use of dredges …no

person shall take any oysters, bay quahaugs, or soft-shell clams from the waters of this state by dredges, rakes, or other apparatus operated by mechanical power or hauled by

power boats.

Harvest Methods

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1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

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Harvest Methods

Licensing

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1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

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)

Year



• Open Access (through mid 1990s)

• 1st Moratorium (1995 – 1998)

• Open Access (1999)

• 2nd Moratorium (2000-2002)

• New Licensing Program (2003)

Licensing

• Use of License Endorsements to limit access to certain species

• Use of Exit/Entry Ratios to control effort levels

– Currently 2:1 for Quahog Endorsement

• Annual process of regulatory review and modification, based on input from industry and advice from RI Marine Fisheries Council

Licensing

Licensing

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1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Lan

din

gs (

MT)

& L

ice

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s (#

)

Year



1984

1985

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1987

1988 1989

1990 1991

1992

1993

1994

1995 1996

1997

1998 1999 2000

2001 2002

2003 2004

2005 2006 2007

2008

2009

2010 2011

2012

0

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600

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

Ab

un

da

nce i

n M

illio

ns (

t)

F Rate (t-1)

Licensing – Stock Assessment model

License Type 2003 Total 2013 Total Net Change

MPL 1191 829 -362

PEL w/QH 924 376 -548

CFL w/QH 271 420 +149

Student SF 107 48 -59

65 & ↑ SF 50 268 +218

TOTALS 2,543 1,941 -602

Licensing

0

200

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600

800

1000

1200

1400

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

# o

f Li

cen

ses

Year

MPURP PEL CFL SFO65 STUD

MPURP Active PEL Active CFL Active SFO65 Active STUD Active

Licensing - # of Active Licenses

0

20

40

60

80

100

120

140

1-5 6-10 11-25 26-50 51-100 101-150 151-200 201-250 251-306

# o

f Fi

she

rme

n

Days Fished

PEL MPURP CFL SF065 Stud

Licensing - 834 Total Active

~ 150 Fishermen

0

20

40

60

80

100

120

# o

f A

ctiv

e F

ish

erm

en

Age

PEL MPURP CFL SFO65 STUD

93 fishermen under 40 years old

Licensing – Age of Fishermen

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20

40

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80

100

120

# o

f A

ctiv

e F

ish

erm

en

Age

PEL MPURP CFL SFO65 STUD

Only 19 full-time

fishermen under 40 years old

(100+ days)

Licensing – Age of Fishermen

0

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6

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12

0

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3000

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Un

em

plo

yme

nt

Rat

e (

%)

Lan

din

gs (

MT)

& L

ice

nse

s (#

)

Year

# of Licenses Meat Weight (MT) Unemployment Rate


Licensing – & unemployment

Daily Catch Limits License

Type Endorsements Limits Cost

Full Harvest

Principal Effort (PEL)

Quahog Soft Shell

Whelk Other

12 bu/day (3 in MAs)

$150 License No Fee for 1st Endorsement

$75 each add’l

Multipurpose (MPL) N/A 12 bu/day (3 in MAs) $300

Limited Harvest

Commercial Fishing (CFL)

Quahog Soft Shell

Whelk Other

3 bu/day $50 License $25 for each Endorsement

Student *Quahog only 3 bu/day $50

Over 65 *Quahog only 3 bu/day No Fee

Recreational (Resident) N/A ½ bu/day (1 peck in MA) No license

Recreational (Non-res) N/A 1 peck/day (1/2 peck in MA) $200 / $25/ $11

𝑁𝑖𝑗 = 𝑁𝑖𝑗−1 ∗ 1 − 𝑝 ∗ 𝑒− 𝐹𝑖𝑗−1+𝑀 + 𝑁𝑖−1𝑗−1 ∗ 𝑝 ∗ 𝑒− 𝐹𝑖−1𝑗−1+𝑀

N = population size F = fishing mortality rate P = promotion probability governed by von Bertalanffy growth equation derived from Henry & Nixon (2008) M = natural mortality rate i = size class j = year

Inputs to Model

1. Landings 2. Fisheries Independent Abundance Index 3. Fishing Effort Index

Daily Catch Limits – Size-structured Stock Assessment Model

0

20

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60

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120

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160

# o

f Q

uah

og

s (

millio

ns)

Year

Landings

Size Structured Stock Assessment Model

Gibson, 2010

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# o

f Q

uah

og

s (

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ns)

Year

Abundance Landings

Gibson, 2010


Polynomial

Logarithmic

Stock-Recruitment Models Great South Bay, NY

How Many Quahogs do We Need?

Kraeuter et al, 2005

Density Dependence

0.75 Adults/m2 = Recruitment Failure

Daily Catch Limits

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600

# o

f Q

uah

og

s (

millio

ns)

Year

AbundanceLandingsRecruitment Failure

0.75 Adults/m2 X 125km2 Fishable Area


Kraeuter et al, 2005

Daily Catch Limits – Spawning Stock & Recruitment

0

100

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300

400

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600

# o

f Q

uah

og

s (

millio

ns)

Year

AbundanceLandingsReduced Recruitment

1.5 Adults/m2 X 125km2 Fishable Area


West Passage

Conditional B

Conditional A

Greenwich

East Passage

ma

ma

ma

ma

West Passage25.9%

Conditional A23.6%

Conditional B20.9%

Greenwich Bay14.4%

East Passage

11.9%

Management Areas0.9%

Coastal Ponds0.8%

Not Identified

0.7%Sakonnet

0.6%Mt Hope Bay

0.3%

Block Island

0.0%

• No info on Closed Waters • Tagging Areas are Large

Area Based Management

• 1993-2013 • Use hydraulic dredge

to sample adult populations

• Stratified Random Sampling Design

• 2368 tows of 30 m • 26,000+ clams

Area Based Management – Dredge Survey

• Not corrected for

dredge efficiency

• High densities correspond to productive fishing grounds

• Shallow areas poorly assessed

• Closed Areas highest densities

Area Based Management – Dredge Survey

Adapted from Gaylord, et al., 2005

Habitat Area

Habitat Area

Protected

Fished

P F

Protected

P


Habitat Area

Habitat Area

Protected

Fished

P F

49% of Studies Fisheries Yield

Higher with Traditional

Management

51% of Studies Fisheries Yield

Higher with MPAs

Gaines, et al., 2010


Habitat Area

Habitat Area

Protected

Fished

P F

Protected

P


Habitat Area

Habitat Area

Protected

F

P F P

P P P P P P P P P

F F F


Rhode Island Management

Habitat Area

Habitat Area

Protected

P F P

P

f

• Management = 67.8km2

• Est. Fishable Area ~ 125km2

F P

F F

P F P p

f p p

f

P P



Management Areas = 67.8km2

Estimated Fishable Area ~ 125km2

Area Based Management – Greenwich Bay

Area Based Management – Greenwich Bay

DEC JAN FEB MARCH APRIL

GB Sub Area 1 & 2 CLOSED OWR 8-12 Jan 2 and starting Jan 6

8-12 MWF 8-12 MWF 8-12 MWF 8-12 MWF

High Banks & Pot C Open Open Open Open Open

Bristol CLOSED 8-12 MWF beginning Jan 3 Open Open Open

Bissel/Fox Opens 2nd Wed* Open* Open* Open* Open*

Mill Gut Opens 2nd Wed Open Open Open Open

• LESLIE'S METHOD • Assume • Nt= No - Ct • Kt = Ct = cumulative catch • Nt = No-Kt • but, “N" is not an observable variable in most studies,so after multiplying

through by q (the catchability coefficient) • qNt = qNo - q(Ct) • CPUE= a + b (Kt) • Fit a regression then

– a) the slope of the line is an estimate of q – b) the intercept is qNo = CPUEo – c) the initial population can be estimated by Intercept a/ slope b

Area Based Management – Leslie Depletion Model


0

5

10

15

20

25

30

35

40

0 50 100 150 200 250

Me

an C

PU

E (m

arsh

mal

low

s/h

and

ful)

Cumulative Catch (Total # of Marshmallows)


0

5

10

15

20

25

30

35

40

0 50 100 150 200 250

Me

an C

PU

E (m

arsh

mal

low

s/h

and

ful)


240 Total Marshmallows


y = -0.1519x + 38.173 R² = 0.9817

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250

Me

an C

PU

E (m

arsh

mal

low

s/h

and

ful)


Starting N Catch exp rate

Volume Start Dens.

End Dens.

F Rate End N

251 240 0.955 12 20.9 0.94 3.1 11


y = -0.1162x + 34.888 R² = 0.9657

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250

Me

an C

PU

E (m

arsh

mal

low

s/h

and

ful)


Estimated 262 Total

Marshmallows


Volume Start Dens.

End Dens.

F Rate End N

262 207 0.791 12 21.8 4.56 1.56 55


y = -0.1162x + 34.888 R² = 0.9657

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250

Me

an C

PU

E (q

uah

ogs

/fis

he

r/d

ay)

Cumulative Catch (Total # of Quahogs)


Area Start Dens.

End Dens.

F Rate End N

262 207 0.791 12 21.8 4.56 1.56 55


December 2009 – March 2010

y = -0.0002x + 1362.9 R² = 0.2653

0

200

400

600

800

1000

1200

1400

1600

0 500,000 1,000,000 1,500,000

Me

an C

PU

E (q

uah

ogs

/fis

he

rme

n/d

ay)

Cumulative Catch (# of quahogs)

Starting # Start #/m2

Catch End # End

#/m2

5,963,116 2.82 1,458,649 4,504,467 2.13

2002-May 2010

Area = 2,109,619 m2

F Rate = 0.281


• May 2010 pollution line changes


• May 2010 pollution line changes

• Summer 2010 DEM conducts dredge survey

• Densities as high as 26 quahogs/ m2 when adjusted for efficiency

• SAP & RIMFC decide to open only Area A (north side)


Dec. 2010- March 2011

y = -5E-05x + 1901.2 R² = 0.6006

0

500

1000

1500

2000

2500

0 1,000,000 2,000,000 3,000,000 4,000,000 5,000,000 6,000,000

Me

an C

PU

E (q

uah

ogs

/fis

he

rme

n/d

ay)



Catch End # End

#/m2

40,983,314 27.09 5,866,505 35,116,809 23.21 Area = 1,512,589 m2

F Rate = 0.154


Dec. 2011- March 2012

y = -8E-05x + 1728.2 R² = 0.5128

0

500

1000

1500

2000

2500

0 2,000,000 4,000,000 6,000,000

Me

an C

PU

E (q

uah

ogs

/fis

he

rme

n/d

ay)



Catch End # End

#/m2

20,765,498 6.51 6,588,476 6,588,478 4.45 Area = 3,189,110 m2

F Rate = 0.382


• May 2012 pollution

lines extended

• Dredge Survey results from Summer 2012

• Densities reduced from ~ 9/m2 to < 1/m2


Jan 2013- March 2013

y = -0.0003x + 1471.7 R² = 0.4798

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 500,000 1,000,000 1,500,000 2,000,000 2,500,000

Me

an C

PU

E (q

uah

ogs

/fis

he

rme

n/d

ay)



Catch End # End

#/m2

4,872,719 1.79 2,012,279 2,860,440 1.05 Area = 2,727,668m2

F Rate = 0.533


Jan 2014 - March 2014

y = -0.0004x + 1522.1 R² = 0.4154

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 500,000 1,000,000 1,500,000

Me

an C

PU

E (q

uah

ogs

/fis

he

rme

n/d

ay)



Catch End # End

#/m2

3,544,222 1.30 1,482,124 2,062,099 0.76 Area = 2,727,668m2

F Rate = 0.542

Habitat Area

Habitat Area

Protected

P F P

P

f



F P

F F

P F P p

f p p

f

P P



Habitat Area

Habitat Area

Protected

P F P

P

f



F P

F F

P F P p

f

p p

f

P P



Habitat Area

Habitat Area

Protected

Fished

P F

Protected

P

SOURCE SINK

For reserves to be effective they must also increase populations beyond reserve borders through: 1. Larval Export 2. Adult Spillover (Transplants?)

Area Based Management - Spawner Sanctuaries

• 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


Greenwich Cove Prohibited


• ~100 million eggs/m2

• Larval Duration 8-12 days

• Large potential reproductive output


Marroquin-Mora & Rice (2008)

• Too Dense?

• Crowding may lead to poor condition and low reproductive output

• CI = dry soft tissue wt X 1000/ (total wt - shell wt)


Matt Griffin RWU/URI

Area Based Management - Transplants

Since 1977 ~ 9 million lbs of quahogs transplanted

High Banks

Potowomut Sanctuary

Greenwich Cove

Area Based Management – Transplants

Potowomut Spawner Sanctuary Approved-Closed

High Banks Management Area Approved

Area Based Management - Transplants

Area Based Management - Spawner Sanctuaries

Data from TNC

Questions?

The Lay of the Land: Understanding Quahog Management in Rhode Island

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Transcript of The Lay of the Land: Understanding Quahog Management in Rhode Island