# Presentation: 830272

## Modeling at  AFSC

- Kerim Aydin, Sarah Gaichas, John Heifetz, Sarah Hinckley, James Ianelli, Pat Livingston, Bern Megrey, Jesus Jurado-Molina, Michael Dalton, Ivonne Ortiz, and Buck Stockhausen
*Subset shown in talk: see abstracts for full list*

## Two major scales of modeling

**Long-term (50+year) predictions**
- Driven by Climate Change predictions:  LOSS OF SEA ICE and OCEAN ACIDIFICATION:  Primarily Biophysical->fish models (bottom-up)
**Interface with current management**
- Folding currently operational models in with the stock assessment and Council processes:  MRM and ecosystem models

## NEMURO:  North Pacific Ecosystem Model for Understanding Regional Oceanography

*“**A conceptual model representing the minimum trophic structure and biological relationships between and among all the marine ecosystem components thought to be essential to describe ecosystem dynamics in the North Pacific” (An MRM for NPZ modeling?)*
*Shown is NEMURO.FISH extension **	**Source: Megrey et al. 2007*

## Marine Seas where the 

- Marine Seas where the
- NEMURO Model has been Applied

## Western Alaskan Sockeye

- British Columbia Sockeye

- Central Alaskan Pink

- Japanese Chum

**Predicted effect of climate change on pink salmon growth:**
- 10% increase in water temperature leads to 3% drop in mature salmon body weight (physiological effect).
- 10% decrease in pteropod production leads to 20% drop in mature salmon body weight (prey limitation).

*(Aydin et al. 2005)*

*Consumption and mortality rates for Pink salmon based on predator and prey biomass*.

**Pink salmon bioenergetics **model, predicts daily pink salmon growth and numerical mortality based on input ration.

**Ecosim** (ecosystem biomass dynamics model), run on a daily timestep.

*Daily  biomass density of phytoplankton, microzooplankton, large zooplankton (copepods).*

**NEMURO** (nutrient-phytoploankton-zooplankton-detritus): 1-dimensional water column model integrated on an hourly timestep.

*Pink salmon body weight and numbers used to set Ecosim biomass for predator and prey equations in next timestep.*

**Notes:**
The high seas of the Gulf of Alaska is a critical feeding and growth area for North American and Asian stocks of Pacific salmon.  Pteropods are an important source of food for several of these species, such as sockeye, pink, and chum salmon, especially during winter months when other food is scarce.  A combined bioenergetcis/food web model predicts that the effects of a 10% reduction of pteropod production would result in a reduction of 20% in the weight of pink salmon returning to Prince William Sound.  This effect is magnified as reduced feeding in the winter months prevents salmon from growing large enough to feed on more nutritious fish and squid in the summer prior to returning to fisheries.   Compare this to a relatively minor predicted 3% drop of growth due to the direct physiological effects of a 10% increase in surface water temperature.   Further, the reduction in winter prey supply would intensify competition between multiple salmon stocks.  Reference:  Aydin et al. (2005) Deep-Sea Res. II: 52: 757-780.

## Larvae have behavior!

**preferred night time**
**depth range **

**preferred daytime**
**depth range **

**+ Growth, Mortality**

- DisMELS: Dispersal Modeling for Early Life Stages (Stockhausen)

**Notes:**
Cartoon of simple behavior incorporated into behavioral model.  Dark grey areas indicate nighttime, yellow areas indicate daytime.  Larvae actively migrate vertically to enter preferred daytime and nighttime depth ranges.  In this example, the larvae undergo conventional diurnal migration: up in the water column at night, lower in the water column during the day.  Diel migration can be “turned off” by setting identical daytime and nighttime depth ranges.  Within a preferred depth range, larvae undergo random walks.

## DisMELS and ROMS(one of multiple efforts interfacing with ROMS)

- Egg
- Stage 1

- Larval
- Stage 1

- Egg
- Stage N

- Larval
- Stage M

- DisMELS and ROMS(one of multiple efforts interfacing with ROMS)

**Notes:**
The ROMS oceanographic model (“Multiply-nested ocean circulation model”) provides time series of 3-d ocean currents as inputs to the “DisMELS” individual-based model for egg and larval dispersion.  The ROMS model can be driven by a number of different atmospheric datasets, including global climate change models.  ROMS also incorporates several NPZ models, and so can provide 3d prey fields, as well.

## PET-ISAM Model for Integrated Assessment

- _Population-Environment-Technology_ Model coupled to _Integrated Science Assessment Model_
- ISAM used to analyze climate change and ocean acidification (Cao, Caldeira & Jain, GRL 2007)

**PET Model     CO2 Emissions**

**Notes:**
West Coast fishery managers rely on county-level data to evaluate the socio-economic impacts of regulation
All familiar with the notion of the "best available data”
But may not be adequate for evaluating impacts on particular communities, and may even limit regional understanding as well. 

requires conservation and management measures to take into account the importance of fishery resources to fishing communities (see discussion under 102). Measures are to provide for the sustained participation of such communities and, to the extent practicable, minimize adverse economic impacts on such communities. An important qualifier was added by the managers' amendment: "consistent with the conservation requirements of this Act (including the prevention of overfishing and rebuilding of overfishing stocks)."

## AIM: Coupled PET-ISAM-EwE

- _Households_
- Capital & Labor
- Consumption & Savings

- _Final Goods Producers_
- Consumption
- Investment
- Government
- Exports & Imports

- _Intermediate goods producers_
- Agriculture
- Fisheries
- Forests
- Energy
- Everything Else (ETE)

- K & L

- C & I

- E & M

**ISAM**

**EwE/**
**Ecosense**

- Seafood

- CO2,
- GHGs

- Climate

## Integration with management

- Conservative exploitation rates/productive stocks (unless you’re a crab).
- Declining mammal and bird stocks (fisheries management with Endangered Species Act considerations)
- Pro-active management: ecosystem committee, ecosystem considerations chapter, but also pro-active lawsuits
**Recent declines in most valuable fishery, the walleye pollock (CASE STUDY for both strategic and tactical integration)**
*Steller Sea Lions *
*Aleutian Islands Fisheries Ecosystem Plan*

## “This” generation

- Multispecies Bycatch Model:
- Technical (Gear) interactions, age structured with detailed management scenarios, no predator/prey links
- MSVPA/MSFOR/MSM/MAMAK
- Multispecies age structured predator/prey for 7 target species, adds explicit predation effects to recruitment hindcasts
- Ecopath/Ecosim
- Includes non-target and protected species dynamics, gear, limited age structure (primarily biomass dynamics)
- An “operational ensemble?”

## INTEGRATION WITH STOCK ASSESSMENT PROCESS

**Initially driven by NEPA, but now strongly positive interactions on all levels**
**Ecosystem Considerations in each stock assessment**
**Ecosystem Assessment**
**Multispecies models**
**Ecosystem Status Indicators**
**Ecosystem-Based Mngt Indices**

## Complexity vs. management reality

- Eastern Bering Sea

- Gulf of Alaska

## Slide 14

## Scoping/strategic analysis GOA predation vs. fishing 2005

**Both F and M**

**(Assessment Fig 9)**

## Strategy implications? Eventual goal.

|  | F>>M2 | F,M2 | M2>>F |
| --- | --- | --- | --- |
| High | Single-species management of highly (over-?) exploited species. | Single-species management may be insufficient to guarantee long-term stability without large swings/ multispecies effects. | Fully utilized species within food web, monitor for production issues, extremely limited fishery. |
| Medium | Single-species management of fully exploited species. | Concern over multispecies implications of fishery. | Partially utilized species within a food web, some concern over fishery. |
| Low | Single-species management of species with low exploitation. | Low concern. | Low concern. |

**(Fishing+Predation)/ Production**

|  | F>>M2 | F,M2 | M2>>F |
| --- | --- | --- | --- |
| High | Single-species management of highly (over-?) exploited species. | Single-species management may be insufficient to guarantee long-term stability without large swings/ multispecies effects. | Fully utilized species within food web, monitor for production issues, extremely limited fishery. |
| Medium | Single-species management of fully exploited species. | Concern over multispecies implications of fishery. | Partially utilized species within a food web, some concern over fishery. |
| Low | Single-species management of species with low exploitation. | Low concern. | Low concern. |

|  | F>>M2 | F,M2 | M2>>F |
| --- | --- | --- | --- |
| High | Single-species management of highly (over-?) exploited species. | Single-species management may be insufficient to guarantee long-term stability without large swings/ multispecies effects. | Fully utilized species within food web, monitor for production issues, extremely limited fishery. |
| Medium | Single-species management of fully exploited species. | Concern over multispecies implications of fishery. | Partially utilized species within a food web, some concern over fishery. |
| Low | Single-species management of species with low exploitation. | Low concern. | Low concern. |

## Broad strategic scoping leads to MRMs, and PARAMETER ESTIMATION/VALIDATION  MSVPA and Multispecies Statistical Model

- Walleye pollock

- Pacific cod

**Fishery**

- Arrowtooth flounder

**(Ianelli and Jurado-Molina)**

**MCMC integrated profile of M**

## MAMAK:  Aleutian fisheries 1979-2003 (Kinzey and Punt)

**MAMAK:  Aleutian fisheries 1979-2003 (Kinzey and Punt)**

- Walleye pollock, Atka mackerel, and Pacific cod provide the basis for the major fisheries of the Aleutian shelf, Alaska.  All three species interact as predators and prey.

**Spawning stock biomass**
- Predation “off”: black dashes
- Predation “on” Types I-VII functional responses: blue lines

- Type II: asymptotic
- Type I: linear
- Type III: S-shaped
- Type IV: ratio interference
- Type V: ratio pre-emption, asymptotic
- Type VI: Hassel-Varley
- Type VII: “Ecosim”

## Calculating Ecosim uncertainty

**(Extended fitting methods applied to multiple functional responses, extended equations, challenging the “primary production anomaly” methodology.)  Gaichas and Aydin**

## Direct “tactical” uses :  A Tale of Two Ecosystems

- Eastern Bering Sea

- Gulf of Alaska

## Slide 21

## Arrowtooth biomass vs. pollock M

Shrimp biomass vs. pollock M

- Shrimp biomass vs. pollock M

- Best fit functional responses (1970-present) dichotomous based on assumed forcing source (e.g. bottom-up vs. arrowtooth larval advection).  Method:  Test all hypotheses.

**GOA Long term:  MSE**

## EBS additional concerns: Zooplankgon and forage fish biomass

**(Assessment Fig. 3)**

## Evolution of single-species assessments to include advice from multispecies models and indicators

***From North Pacific Fisheries Management Council’s Scientific and Statistical Committee minutes, December 2006:***
- “The [eastern Bering Sea walleye pollock] stock remains above the MSY level, having declined ... at a rate of about 19% per year....A series of 4 below-average recruitments has contributed to the decline...the series of low recruitments will result in an age-structure that is dominated by only a few year-classes which could increase fluctuations in the population.”
- “Other issues raised in the stock assessment suggest a need for further caution.”
- a northward shift ... with some portion of the population into Russian waters.
- a large decline in zooplankton, which is important in providing forage for juvenile pollock.
- increasing predation by arrowtooth flounder on juvenile pollock, which could contribute to further declines in adult pollock biomass.
**“****Consequently, the SSC agrees with the Plan Team that a reduction in Allowable Biological Catch from the maximum permissible is justified.”**

**Result from single-species assessment**

**Assessment + ecosystem indicators**

**Ecosystem indicators**

**A multispecies model**

## KEY IS FOLDING IN TO STOCK ASSESSMENT PROCESS.  THIS SYSTEM WORKS WHEN IT IMPACTS A TARGET SPECIES, BUT THERE IS LIMITED MANAGEMENT MANDATE FOR INTERACTIONS.

**KEY IS FOLDING IN TO STOCK ASSESSMENT PROCESS.  **THIS SYSTEM WORKS WHEN IT IMPACTS A TARGET SPECIES, BUT THERE IS LIMITED MANAGEMENT MANDATE FOR INTERACTIONS.
**Perhaps Fisheries Ecosystem Plans will create context, avoid crisis mode?**