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Surviving the Gauntlet
A comparative study of the pelagic, demersal, and spatial
linkages that determine groundfish recruitment and diversity in
the Gulf of Alaska ecosystem
NPRB Gulf of Alaska Integrated Ecosystem Research Program
Upper Trophic Level Component
Jamal Moss, Kalei Shotwell, Shannon Atkinson, & Franz Mueter
UTL Introduction and Overview
• Gulf of Alaska (GOA)
– Highly complex and dynamic marine environment
– Strong gradients in population stability and species
composition over space and time
– Mechanisms are poorly understood
• Purpose
– Improve our understanding of the variability in this
ecosystem through regional comparison of
recruitment variability in five predatory fish species
and examine the effects of this variability on top level
predators such as seabirds and Steller sea lions
UTL Core Hypotheses
• Early life survival of marine fish
– Influenced by climate driven variability in a biophysical gauntlet
• Described by productivity, transport, and settlement
– Linked to health and condition of fish traveling the gauntlet
• Dietary preference and foraging strategy of top level
predators (seabirds & Steller sea lions)
– Influenced by fluctuations of available prey
– Linked to differences in survival of fish among years and areas
• Eastern GOA more ecologically resilient to climate
change and human forcing than central GOA
– Environmental and biological variability are less pronounced
– Greater stability and higher species diversity
UTL Objectives
• Quantify temporal variability of drivers influencing early
life survival of key groundfish species by region
– Retrospective analysis of available datasets
• Determine abundance, distribution, and condition of key
groundfish species during the pelagic stage
– Field sampling via gridded stations by region
– Laboratory work for health assessment in pelagic stage
• Create habitat suitability maps to characterize nearshore
demersal habitat by region
• Analyze dietary preference and foraging behavior of top
level predators and relate diet to available prey
– Seabirds and Steller sea lions
Supporting Objectives
• LTL/Physical Oceanography
– Characterize biophysical environment for larval and juvenile
fishes in eastern and central GOA
• Dominant physical mechanisms for transport
• Cross-shelf patterns in prey fields
– Coordinate with modeling component to help "groundtruth" the
bio-physical model
• MTL/Forage Base
– Characterize forage fish distribution and abundance in the
eastern and central GOA relative to YOY of our focal species
• During offshore/nearshore pelagic and nearshore settlement stages
– Coordinate with modeling component to inform various models
Supporting Objectives
• Modeling Component
– Develop biophysical model to generate hindcasts & potentially
forecasts of LTL variability for key prey groups
– Quantify the effects of LTL variability on recruitment, competition,
and predator-prey interactions among key groundfish species
– Develop recruitment indices for at least two species with
contrasting dispersal rates, we recommend sablefish & POP
• Model connectivity between spawning areas and suitable nursery
areas under different environmental conditions
– Conduct Management Strategy Evaluations (MSE) through
simulation of multi-species dynamics under different climate and
fishing scenarios
– Coordinate with LTL and MTL to groundtruth and inform models
Background & Justification
• Recruitment
– Focus on egg to Young-of-the-Year (YOY) critical period
• Functional grouping of five top predatory groundfish
– Pacific Cod, Pollock, Sablefish, POP, Arrowtooth Flounder
– Majority of predator biomass in GOA & variety of life histories
• Competition, predation, & environmental variability
– Recruitment less related to fishing and adult spawning biomass
• Regional comparison
– Eastern GOA: stable, narrow shelf, high diversity, lower biomass
– Central GOA: variable, wide shelf, low diversity, higher biomass
Proposed Activities and Objectives
•
•
•
•
•
Retrospective analysis
Offshore to nearshore pelagic stage
Nearshore settlement stage
Health assessment
Top predator stage
Retrospective Analysis
• Goal
– Provide baseline information on ecosystem processes at multiple
trophic levels in the eastern and central GOA
• Objectives
– Quantify temporal variability at multiple trophic levels and identify
cold & warm “regimes”
– Characterize faunal break between eastern & central GOA inshore to offshore and across trophic levels
– Provide indices to modeling components
• Approach
– Compile relevant data sets (e.g. Table 1 in proposal)
– Univariate & multivariate analysis of spatial & temporal patterns
of variability
Potential Datasets
Database Title
Database Description
Years
Sea Surface Temperature
AVHRR Pathfinder, 4 km resolution with derived products
1985 – present
Sea Surface Height
Merged surface elevation data, 25o resolution, derived products
1992 – present
Surface Vector Winds
QuikScat winds, 25 km resolution and derived products
1999 – present
Ocean color
SeaWiFS and MODIS chlorophyll a and primary productivity
1998 – present
Seward line
Seward line, oceanography & zooplankton
1997 – present
SECM Project
Icy Point transect, oceanography & zooplankton
1997 – present
GLOBEC fish &
oceanography data
Fish and oceanography data collected during GLOBEC project in
GOA, includes catch, diet, and energy content
2001 – 2004
AFSC Ichthyoplankton
Ongoing ichthyoplankton sampling in western and central GOA
1977 – present
ABL Longline survey
Annual survey in the GOA and BSAI sampling groundfish
1978 – present
NMFS Trawl survey
Bottom trawl survey on demersal fish catch per unit of effort
1984 – present
Seabird database
Seabird measurements at selected trend sites in the GOA
1994 – present
NP Pelagic seabird data
Data on pelagic distribution and abundance of seabirds
1972-2003
Steller sea lion diets
Nutritional quality of Alaskan fish for predators
2000 – present
usSEABED
Nation-wide integrated seafloor characterization database
Offshore/Nearshore Pelagic Stage
• Goal
– Characterize offshore to nearshore pelagic environment for
determining successful recruitment of key groundfish species
• Objectives
– Determine abundance and spatial distribution of five groundfish
species and quantify regional differences
– Describe surrounding environmental conditions to include
oceanography, prey, competitor, and predator fields
• Approach
– Comprehensive pelagic sampling grid in two regions (Figure 1)
– Seasonal at-sea sampling
• Physical and biological oceanographic measurements (all seasons)
• Surface trawling similar to BASIS and GLOBEC (summer/fall)
• Avian and marine mammal observations (summer/fall)
Proposed Survey Station Grid
Figure 1
East Amatuli
Nearshore Settlement Stage
• Goal
– Describe preferred habitat and characterize nearshore for
determining successful recruitment of key groundfish species
• Objectives
– Develop habitat suitability maps for five groundfish species and
quantify regional differences
– Determine role of nearshore habitat, prey, competitor and
predator fields for successful settlement
• Approach
– Combine detailed bathymetry, substrate, and species habitat
preferences to create habitat suitability maps by region
– Overlay data on nearshore prey, competitor, and predator fields
to predict ability of YOY to feed, compete, and avoid predation
• Nearshore stations from existing and new surveys
Health Assessment
• Goal
– Measure health of key groundfish species throughout biophysical
gauntlet to link to successful recruitment
• Objectives
– Estimate instantaneous growth, condition, and consumption
rates throughout gauntlet
– Develop bioenergetic models of potential fish growth for each
species, region, and habitat
• Approach
– Calculate metabolic and consumption rates in laboratory from
samples taken during at-sea surveys
– Estimate growth potential by evaluating prey quality/consumption
and instantaneous growth
– Use condition estimates to develop simple bioenergetics models
TSMRI Laboratory
Top Predator Pelagic Stage
• Goal
– Determine predation pressure on YOY marine fish and prey
accessibility during pelagic stage
• Objectives
– Estimate predator field during summer and fall offshore to
nearshore pelagic surveys
– Identify potential hotspots of foraging activity and relate to
environmental observations
• Approach
– Conduct standard transect surveys for seabirds and marine
mammals, and surface trawl or existing surveys for fish
– Compare foraging activity to station oceanography and satellite
measurements to identify hotspots
Seabird Diet
• Goal
– Determine relationship between factors influencing recruitment
success of key groundfish species and changes in dietary
preference and foraging strategy of seabirds
• Objectives
– Compare dietary preference and foraging strategy in seabirds for
eastern and central GOA
• Approach
– Continue standard diet collections on St. Lazaria and East
Amatuli islands
– Equip rhinoceros auklets with platform terminal transmitter tags
to evaluate feeding patterns during chick-rearing
• Quantify time-budgets for nesting, foraging habits and effort
Seabird Observations
• Onboard seabird observations
– Spatial, temporal, and seasonal distribution
•
Diet collections at St. Lazaria and East Amatuli
– Summers 2012-2013
•
Rhinoceros auklet PTT tagging
– Evaluate foraging patterns during chick rearing
– Quantification of time-budgets while on land
•
Auklet chick enumeration & growth rate
Rhinoceros
auklet
Fork-tailed
storm-petrel
Common
Murre
Leach’s
storm-petrel
Tufted
Puffin
Steller sea lion (SSL) Diet
• Goal
– Determine relationship between factors influencing recruitment
success of key groundfish species and changes in dietary
preference and foraging strategy of SSL
• Objectives
– Compare dietary preference and foraging strategy in SSL for
eastern and central GOA
• Approach
– Undertake scat collections and analysis from eastern and central
SSL rookeries and haulouts
– Estimate frequency of occurrence of prey species for various age
and sex classes of SSL
– Calculate diet diversity index by region and compare
with abundance trends
Steller Sea Lion Observations
• Enumeration (pups, males, females)
•
• Scat collections from eastern and central regions
(2012-2013)
– Fish hard part analysis/diet composition
– Corticosterone assay to test for age and sex effects on diet
– Diet diversity index calculated for each region
Data Products
• Retrospective Analysis
– Datasets, spatial indices
• Sampling Grid
– Distribution and abundance of predatory fish species
• Habitat
– Detailed bathymetry and substrate maps
– Suitability maps and indices by species, region
• Health Assessment
– Growth estimates, metabolic and consumption rates
• Top Predators
– Density estimates from at-sea transects
– Diet data for seabirds and Steller sea lions
Products Timeline
Year
2009
Quarter
3
Planning and preparation
Retrospective analysis
Fisheries survey pilot year
Fisheries survey full year
Fish sample processing
Habitat suitability analysis
SSL collections
Scat sample processing
Seabird data collection
Data analysis
Manuscript writing
4
2010
1
2
3
2011
4
1
2
3
2012
4
1
2
3
2013
4
1
2
3
2014
4
1
2
3
Fisheries Oceanographic Surveys
• CTD cast to 10m from
bottom or 200m
• Zooplankton net tows (2)
• 30-minute surface trawl
• Underway seabird and
marine mammal
observations
http://globec.oce.orst.edu
Fish Collections
Sampling Logistics
2011
2012
2013
Summer (July/Aug)
Autumn (Sept/Oct)
Space for 3 LTL and MTL scientists on charter, 6 on Oscar Dyson
Data Needs
• LTL Component:
– Spring survey to characterize biophysical environment and sample
eggs/larvae
– Estimates of biophysical environment during summer and fall surveys at
each grid station
• MTL Component:
– Estimates of forage base during summer and fall surveys at each grid
station and in the nearshore settlement areas
• Modeling:
– Biophysical model
– Transport model for two species with contrasting dispersal rates
• Identify POP samples and use genetic dispersal to inform transport model
– Model quantifying effects of LTL variability on recruitment, competition,
and predator-prey interactions among key groundfish species
– MSE through simulations of different fishing and climate scenarios
Questions???
Required Products List
Project
Goal
Link to UTL component
GOA IERP
Component
Biophysical model
(e.g. ROMS-NPZ)
Refine existing model and run hindcasts
and possibly forecasts to quantify LTL
variability
Provide model-based indices of LTL
variability (hindcast), and future
projections of these indices, for multispecies model simulations
4
GOA field
sampling
Characterize offshore to nearshore
pelagic environment to ground-truth and
parameterize biophysical models
Provide observation-based
oceanographic and zooplankton
indices for central and eastern GOA
2,3,4
Ichthyoplankton
sampling
Quantify distribution of larval stages of
focal species in the eastern GOA and
oceanographic conditions for all surveys
Add to comprehensive comparison of
eastern and western GOA. Provide
starting values of egg and larval
distribution for transport models.
3
Juvenile nursery
areas
Identify juvenile nurseries in nearshore
areas of the eastern and central GOA
based on existing data and new field
sampling as needed
Provide estimate of nearshore forage
and competition for developing habitat
suitability indices per species
2
Transport models
such as Individual
Based Model
(IBM)
Simulate transport of early life history
stages to quantify spatial match between
simulated transport and suitable habitat
(hypothesized nursery areas)
Provide index of recruitment success
for inclusion in multi-species models
and simulations.
2,4
Integrate transport and dispersal models
with the underlying genetic signal
Model should combine, genetic,
oceanographic, and behavioral
aspects of the species to realistically
characterize larval and YOY dispersal
4
Pacific ocean
perch YOY
genetics