A Framework for Ecosystem
Impacts Assessment Using an
Indicator Approach
Patricia A. Livingston1, K. Aydin1, J. Boldt2, J. Ianelli1,
and J. Jurado-Molina2
1Alaska
Fisheries Science Center Seattle, WA, USA
2JISAO, University of Washington, Seattle, WA USA
Overview
• Alaskan context
• Evolution and Description of the
Framework
– Documentation of status and trends
– Evaluation of past and present impacts
– Prediction of future trends and management
options
US Legislation on
Environmental Protection
National
Environmental
Protection
Act
1969
Marine Mammal
Protection Act
1972
Magnuson-Stevens Fishery
Conservation and
Management Act
1976
Clean Water
Act
1972
Endangered
Species Act
1973
Ecosystem-based Management Actions
•
TAC less than ABC for individual stocks
•
OY cap on total groundfish yield
•
No target fisheries on forage
•
Short-tailed albatross take
restrictions, Seabird bycatch
mitigation devices
•
No fishing in Steller sea lion foraging
area and minimum biomass threshold
for sea lion prey
•
Trawl closures, bottom trawling
restrictions
•
Bycatch and discard controls
Conservative single species targets
Catch 
TAC

ABC

OFL
CAP on TOTAL TARGET CATCH
Total yield < 2 million tonnes
Key Pieces of the Framework
Establish assessment
Framework, objectives,
Thresholds, indicators
Gather information
Historical status
and trends
Ecosystem components
and stressors
Generate management
Alternatives,
Future scenarios
MODELS for Prediction
DECISION
Expert judgment
to analyze impacts
And provide advice
Ecosystem Measures and Influences
Closed Areas
Status
Catch
Levels
Gear
Effort
Management
Physical
Forcing
Ecosystem Impacts Assessment
Framework:
Objectives, sub-objectives, ecosystem indicators
SUBOBJECTIVES
• More focused, tangible
• Relate to key areas/issues
INDICATORS
• Measures of particular
ecosystem attributes
for protection
• May vary across
ecosystems depending on
differences in threats,
stressors, ecosystem
characteristics
• Thresholds relate to legal
mandates under various
laws
• Qualitative analysis of
change used when
targets/thresholds are not
defined
• Requires expert judgment
Ecosystem Processes
ECOSYSTEM DEFINITION
• Populations and
communities of
interacting organisms
and physical
environment with
characteristic trophic
structure and material
(energy) cycles
OBJECTIVES FOR ECOSYSTEM
PROTECTION
• Maintain Predator/prey
•
•
relationships
Maintain Energy/flow
balance
Maintain Habitat and
Diversity
Objectives for Ecosystem Protection:
 Maintain predator-prey relationships
pelagic forage availability
spatial/temporal conc. of fishery impact on forage
fish
removals of top predators
introduction of non-native species
CLIMATE and FISHING
 Maintain diversity
species diversity
functional (trophic, structural habitat) diversity
genetic diversity
 Maintain energy flow and balance
human-induced energy redirection
system impacts attributable to energy removal
Ecosystem Impacts Assessment
Framework:
Objectives, sub-objectives, ecosystem indicators
OBJECTIVE: MAINTAIN PREDATOR/PREY RELATIONSHIPS
SUBOBJECTIVE1: Sustain top predator populations
THRESHOLD: Catch levels high enough to cause the biomass of
one or more top level predator species to fall below minimum
biologically acceptable limits
INDICATORS:
• Population status of top predator species
• Bycatch levels of sensitive top predators that lack population
•
estimates (sharks, birds)
Trophic level of the catch
Effects Analysis
Objective
Subobjective
Significance Threshold
Indicators
Predatorprey
relationships
Pelagic forage
availability
Fishery induced changes outside the
natural level of abundance or
variability for a prey species relative
to predator demands
Population trends in pelagic forage
biomass (quantitative - pollock, Atka
mackerel, catch/bycatch trends of forage
species, squid and herring)
Spatial and
temporal
concentration of
fishery impact
on forage
Fishery concentration levels high
enough to impair the long term
viability of ecologically important,
nonresource species such as marine
mammals and birds
Degree of spatial/temporal concentration
of fishery on pollock, Atka mackerel,
herring, squid and forage species
(qualitative)
Removal of top
predators
Catch levels high enough to cause
the biomass of one or more top level
predator species to fall below
minimum biologically acceptable
limits
Trophic level of the catch
Sensitive top predator bycatch levels
(quantitative: sharks, birds; qualitative:
pinnipeds)
Population status of top predator species
(whales, pinnipeds, seabirds) relative to
minimum biologically acceptable limits
Introduction of
nonnative
species
Fishery vessel ballast water and hull
fouling organism exchange levels
high enough to cause viable
introduction of one or more nonnative
species, invasive species
Total catch levels
Effects Analysis (cont.)
Objective
Subobjective Significance Threshold
Indicators
Energy
flow and
balance
Energy redirection
Long-term changes in system
biomass, respiration,
production or energy cycling
that are outside the range of
natural variability due to
fishery discarding and offal
production practices
Trends in discard and offal production
levels
(quantitative for discards)
Scavenger population trends relative
to discard and offal production levels
(qualitative)
Bottom gear effort (qualitative
measure of unobserved gear
mortality particularly on bottom
organisms)
Energy
removal
Long-term changes in
system-level biomass,
respiration, production or
energy cycling that are
outside the range of natural
variability due to fishery
removals of energy
Trends in total retained catch levels
(quantitative)
Effects Analysis (cont.)
Objective
Subobjective
Significance Threshold
Indicators
Diversity
Species
diversity
Catch removals high enough to cause
the biomass of one or more species
(target, nontarget) to fall below or to
be kept from recovering from levels
below minimum biologically
acceptable limits
Population levels of target, nontarget species
relative to MSST or ESA listing thresholds,
linked to fishing removals (qualitative)
Bycatch amounts of sensitive (low potential
population turnover rates) species that lack
population estimates (quantitative: sharks,
birds, HAPC biota)
Number of ESA listed marine species
Area closures
Functional
(trophic,
structural
habitat)
diversity
Catch removals high enough to cause
a change in functional diversity
outside the range of natural variability
observed for the system
Guild diversity or size diversity changes linked
to fishing removals (qualitative)
Bottom gear effort (measure of benthic guild
disturbance)
HAPC biota bycatch
Genetic
diversity
Catch removals high enough to cause
a loss or change in one or more
genetic components of a stock that
would cause the stock biomass to fall
below minimum biologically
acceptable limits
Degree of fishing on spawning aggregations or
larger fish (qualitative)
Older age group abundances of target
groundfish stocks
MANAGEMENT INDICATORS
Eastern Bering Sea
4
2,500,000
3500
Total catch (t)
2,000,000
Observed bottom trawl duration (24hr days)
3000
2500
2000
3
1,500,000
1,000,000
Total catch
GOA
AI
2
Trophic level of
catch
500,000
1
0
BS
1500
Trophic level (catch)
Time trends in bottom trawl effort
1954 1959 1964 1969 1974 1979 1984 1989 1994 1999
1000
Total catch and trophic level of catch
500
0
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
BSAI Non-target
2001
Year
70000
30,000
25,000
200,000
20,000
150,000
15,000
100,000
10,000
50,000
Effort (1000 hooks)
Number of seabirds
0
5,000
0
1993 1994 1995 1996 1997 1998 1999 2000 2001
Year
Incidental take of seabirds
Longline effort (1,000 hooks)
250,000
50000
40000
30000
20000
10000
0
1997
1998
1999
2000
2001
2002
HAPC
GOA Non-target
35000
Amount
and composition
of non-target
fish
non-specified
forage
species30000
in catch
tch (tons)
Seabird bycatch and fishing effort
Total Catch (tons)
60000
25000
20000
other species
ECOSYSTEM STATUS INDICATORS
Seabird population
trends
Seabird Population Trends
Fish community size spectrum
Size frequency distribution all fish
16
Environmental fluctuations
14
12
12
11
10
4
1 .0 0
In d e x
2
0
SE Bering
SW Bering
Gulf of Alaska
Southeast
- 1 .0 0
Negative trend
No discernable trend
Positive trend
7.000-8.000
8.000-9.000
6.000-7.000
5.000-6.000
4.000-5.000
3.16
N.
Bering/Chukchi
0 .0 0
5
4
3
2
1
0
ln (length midpoint +1)
- 2 .0 0
2000
2 .0 0
9.000-10.000
1997
1 5 - m o n t h ru n n in g m e a n
10.000-11.000
1994
5 - m o n t h ru n n in g m e a n
6
7
6
1991
ln (N +1)
1988
PD O
11.000-12.000
1985
3 .0 0
9
8
4.42
1982
8
3.98
4 .0 0
4.23
10
3.65
Frequency
Pa c ific D e c a d a l O sc illa tio n
3.000-4.000
Year
2000
1995
1990
1985
1980
1975
1970
1965
1960
1955
1950
1945
1940
1935
1930
1925
1920
1915
1910
1905
- 4 .0 0
1900
- 3 .0 0
Ye a r
Status of structural habitat biota
2000
1500
1000
2000
1998
1996
1994
1992
1990
1988
1986
0
1984
500
1982
Biom ass (t)
SEAPENS/W HIPS
Population trends of non-target fish species
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1982 1984 1986 1988 1990 1992 1994 1996 1998
YE AR
L yco d es
S a rr i t o
P o d o th
I cel u s sp
G ym n o c
T ri g l o p
C ycl o p t
B a t h ym
D a syco t
H exa g ra
The Framework: Part 1 Evaluate Present Status
Ecosystem Considerations Section
• Accompanies single species stock assessment advice to
North Pacific Fishery Management Council since 1995
• Provides status and historical trend information of
ecosystem components using scientific information from a
variety of experts and agencies: Assess Present Status
• Contains species, community, and ecosystem-level
indicators and indicators of environmental and human
impacts
• Track efficacy of ecosystem-based management efforts
• Meets the national fishery management scientific
information requirement (National Standard 2) to include
information on past, present, and possible future condition
of the stocks, marine ecosystems, and fisheries being
managed in the stock assessment and fishery evaluation
reports provided to managers.
The Framework Part 2:
Need
for
Ecosystem
Assessment
Moving Beyond Status and Trends
• Requires an ecosystem impacts assessment framework
• Prediction of possible future trends under various
management strategies: MODELS
• Provide guidance on possible aggregate effects of fishing
and climate that are not captured under single species
assessments
• Uses NEPA as the umbrella legislation for providing an
ecosystem-based management framework that considers
the ecosystem first
Ecosystem Impacts Assessment
Framework: PREDICTION
KEY CONSIDERATIONS
1. MODELS that incorporate processes of
interest
2. MANAGEMENT ALTERNATIVES to evaluate
• Annual quota-setting
• Management strategy evaluation of
policies
3. SCENARIOS of future environmental state
Impacts Analysis
B0
(unfished)
New
overfishing
level
Spawning Biomass
Catch
Bmsy
Old
overfishing
level
Stock
Fmsy
0
Fishing Mortality
Change in Discards by Management Alternative
60.0
Percent change from
baseline
Elements:
• Predefined thresholds
or amounts of
acceptable change in
an indicator
• Expert judgment
• Falling below
threshold or too much
change in indicator
triggers action or
eliminates
management
alternative
• Performed at
ecosystem and
individual fishery level
40.0
20.0
0.0
1
2
3
4
5
6
7
8
-20.0
-40.0
Discards
-60.0
Threshold
-80.0
Management Alternative
9
Future Challenges
• Improve predictive capability with regard to climate and
human impacts on ecosystems: model refinement and
regime shift analysis to drive recruitment scenarios
• More explicit definition of ecosystem-based management
objectives: may require public involvement in defining
specific regional objectives for management
• Developing objective criteria and sensitive indicators to
measure the success in achieving desired ecosystem state
or condition (or avoidance of undesirable states)
• More formalized decision-making framework