From Fishing Capacity to Diversity; Changing Fishery
Management Priorities in the US New England
Groundfish Fishery
Eric Thunberg, NOAA Fisheries, Office of Science and Technology
Steven Correia, Massachusetts Division of Marine Fisheries
Outline
 Introduction
 Management priority timeline
 Measures of Fleet Diversity
 Richness
 Shannon Index
 Evenness
 Data and Methods
 Results
 Conclusions
Management Priorities Over Time
Count of topics in Federal Register summaries
A18
A13
A16
10
6
2
diversity
10
6
2
A13
A16
 Federal Register
meeting summaries
proxy for topic
importance
accumulation limits
A13
A16
10
6
2
10
6
2
A13
A16
buyout
A13
A16
10
6
2
 Issues related to
capacity dominated
from 1996 to 2004
consolidation
10
6
2
A13
A16
latent-effort
A13
A16
10
6
2
capacity
year
2014
2012
2010
2008
A16
2006
2004
2002
2000
A13
1998
10
6
2
1996
count
fleet visioning
 Issues related to
diversity begin to
crop up in 2005 with
more frequency from
2009 to Present
Fleet Diversity
FMP Objective to Maintain a Diverse Fleet
 Gear type, vessel size, locations, levels of participation
Fleet Visioning
 Gear type, vessel size, location
Amendment 18
 Gear type, vessel size, location, ownership patterns,
level of participation through permit banks
Primarily framed in terms of presence or absence
 Lends itself to biodiversity measures
General Diversity (Hill 1973)
 “Diversity Order” determined
by q
Eggs
Juveniles
 Weight put on less abundant vis à vis more abundant species
 For q > 0 and < 1 greater weight on less abundant
 For q > 1 greater weight on more abundant
 For q = 0; Richness
 For q = 1; Shannon Index
Atlantic
Cod EFH
 For q = 2; Simpson’s Index
Adults
Effective Diversity and Evenness
 Effective diversity; the number of vessel types that
would be present if all types were equally abundant
 Shannon; 1D = eSH
 Simpson; 2D = 1/S
 For any population with equal abundance;
 eSH = 1/S = Richness
 Evenness; The degree to which all vessel types are of
equal abundance
 Gini Coefficient
Data and Methods
Vessel Types (368 possible vessel types)
 Gear – hook, longline, gillnet, trawl
 Vessel size - < 30, 30 to < 50, 50 to < 75, >= 75
 Port Group – 23 sub-regions
Preponderance of groundfish landings used to assign
vessel types; 1996-2012
Vessel trip report data
Total of 132 vessel types “existed” in at least 1 year
Results – Diversity Measures
Trends in three indices
 From 1996 to 2012
400 600 800 1000
Groundfish Active
 -69% in active vessels (1,098 to 337)
 -46% in richness (95 to 51)
 -37% in effective diversity (51 to 32)
 Times series break in 2001; prior to
2001 fleet size, richness, and effective
diversity change at similar rates -0.6% to
-1.7%
50
60
70
80
A16
Shannon Effective Diversity
40
45
50
 2002-2010 fleet size down at an average
annual rate of 11%, richness down 5%
35
Year
2012
2010
2008
2006
2004
2002
2000
1998
A16
1996
Index
90
Number of Vessel Types
 Effective diversity down 2002-2008 by
5% per year, but stable since 2008 (31 to
34)
Evenness (Gini Coefficient)
Trends in eveness (Gini Coefficient)
0.62
0.58
0.56
2012
2010
2008
2006
2004
2002
2000
1998
0.54
1996
Gini index
0.60
Fishing year
Average annual percent change -1.7% since
2002
Abundance among vessel types has become
more even since 2002.
Gear Effects on Shannon Index
Shannon share by gear type
trawl
0.65
A16
0.60
Time series median trawl
60%, gillnet 23%, longline
8%, hook 7%
A16
gill
0.20
longline
A16
Time series break in 2001
– increase in trawl, drop
in longline
0.15
0.10
Consistent upward trend
in gillnet and trawl,
downward trend in
longline and hook
0.05
hook
0.08
0.06
Year
2012
2010
2008
2006
2004
2002
2000
1998
0.04
1996
Shannon Share
0.25
Vessel Size Effects on Shannon Index
Shannon share by vessel size
A16
75+ ft
0.16
0.15
0.14
 Time series median <30 (5%),
30 to 50 (51%), 50 to 75
(31%), >75 (13%)
0.13
0.12
50 to 75 ft
 Size classes 30 to 50 and 50 to
75 vary around median
30 to 50 ft
 -10% average annual change
in small vessel share (19962008)
0.33
0.31
0.30
0.53
0.52
0.51
0.50
0.49
< 30 ft
0.07
0.06
0.05
0.04
0.03
Year
2012
2010
2008
2006
2004
2002
2000
1998
0.02
1996
Shannon Share
0.32
A16
 3% average annual change in
large vessel share (20022012)
Port Group State Effects on Shannon Index
 MA 53% of index, increase 1% per year through 2009 down 2010-2012
 ME 16% of index 1996-2005, down 8% per year 2006-2010, serial
“extinction” of key vessel types.
 RI 10% of index, 2003-2012 increasing at average annual rate of 6%
NY
0.10
0.14
0.09
0.12
0.08
RI
ME
MA
0.15
0.55
0.10
0.50
0.10
1996
1998
2000
2002
2004
2006
2008
2010
2012
1996
1998
2000
2002
2004
2006
2008
2010
2012
0.08
1996
1998
2000
2002
2004
2006
2008
2010
2012
0.07
1996
1998
2000
2002
2004
2006
2008
2010
2012
Shannon Share
Shannon share by state
Year
A16
Other
CT
NJ
0.03
0.02
0.070
0.04
0.010
NH
0.075
0.05
0.015
0.065
0.03
0.060
1996
1998
2000
2002
2004
2006
2008
2010
2012
1996
1998
2000
2002
2004
2006
2008
2010
2012
0.005
Year
1996
1998
2000
2002
2004
2006
2008
2010
2012
0.01
1996
1998
2000
2002
2004
2006
2008
2010
2012
Shannon Share
Shannon share by state
Conclusions
 Diversity indicators show downward trend
 Effective diversity stable since 2008
 More even distribution of relative abundance
 Evidence of shifts among vessel types
 ↑ share for trawl and gillnet gears
 ↑ share for larger vessels, ↓ share of small vessels
 Massachusetts more than 50% of Shannon index
 ↓ share in Maine port groups
 ↑share in Rhode Island port groups
Conclusions (continued)
 40 of 132 vessel types present in all 17 years
 These 40 vessel types accounted for 85% of Shannon index,
93% of groundfish landings, and 89% of fleet size
 46 vessel types present in 5 or fewer years
 Extirpation or artifact of decision rules?
 Loss of a rare vessel type reduces diversity
 Loss of abundant vessel type increases diversity
 Evaluate rules for assigning vessel type
 Low frequency of “switch” due to vessel size
 About 25% due to gear
 Over 60% of change in vessel type due to port group