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H—Information from Interstate Marine Fisheries Commissions and States
To aid the committee's deliberations, information was requested from the Atlantic, Gulf, and Pacific States Marine Fisheries Commissions. The committee specifically asked the commissions for information about what methods their states use to assess marine fish stocks in state waters (to compare with methods used by National Marine Fisheries Service [NMFS] and the regional fishery management councils). The commissions were also asked to relay their concerns about existing stock assessment methods. This information is shown below; they are the views of the commissions and their staff and do not necessarily coincide with the views of the committee. The response from the Atlantic States Marine Fisheries Commission was received first and was forwarded to the other commissions.
Commission and State Concerns and Comments Regarding Stock Assessments
Atlantic States Marine Fisheries Commission (ASMFC)
The complexity of many stock assessments models leads to a lack of understanding among those who may not have a scientific background. More effort is needed to provide less technical explanations of stock assessment models and results.
Discrepancies in model results due to incomplete characterization of input parameters lead to less effective and timely fisheries management, and lack of public confidence in the scientific process and expertise.
Probability analysis should be included as a part of all stock assessments to provide an indication of the level of achieving management and rebuilding goals.
Deficiencies in fisheries-dependent data bases limit the effectiveness of many stock assessments; i.e., catch at age, discards.
Deficiencies in information concerning critical model parameters may limit stock assessments; i.e., fishing and natural mortality, bias in catch data, stock distribution, and life history parameters.
Harvest regulations may affect input data. For example, the effect of size limits may be to truncate length-frequency data thereby affecting the model results.
Biases in model results may occur due to equilibrium assumptions; i.e., yield-per-recruit modeling.
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H— Information from Interstate Marine Fisheries Commissions and States
To aid the committee's deliberations, information was requested from the Atlantic, Gulf, and Pacific States Marine Fisheries Commissions. The committee specifically asked the commissions for information about what methods their states use to assess marine fish stocks in state waters (to compare with methods used by National Marine Fisheries Service [NMFS] and the regional fishery management councils). The commissions were also asked to relay their concerns about existing stock assessment methods. This information is shown below; they are the views of the commissions and their staff and do not necessarily coincide with the views of the committee. The response from the Atlantic States Marine Fisheries Commission was received first and was forwarded to the other commissions.
Commission and State Concerns and Comments Regarding Stock Assessments
Atlantic States Marine Fisheries Commission (ASMFC)
The complexity of many stock assessments models leads to a lack of understanding among those who may not have a scientific background. More effort is needed to provide less technical explanations of stock assessment models and results.
Discrepancies in model results due to incomplete characterization of input parameters lead to less effective and timely fisheries management, and lack of public confidence in the scientific process and expertise.
Probability analysis should be included as a part of all stock assessments to provide an indication of the level of achieving management and rebuilding goals.
Deficiencies in fisheries-dependent data bases limit the effectiveness of many stock assessments; i.e., catch at age, discards.
Deficiencies in information concerning critical model parameters may limit stock assessments; i.e., fishing and natural mortality, bias in catch data, stock distribution, and life history parameters.
Harvest regulations may affect input data. For example, the effect of size limits may be to truncate length-frequency data thereby affecting the model results.
Biases in model results may occur due to equilibrium assumptions; i.e., yield-per-recruit modeling.
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TABLE H.1 Stock Assessment Methods Used by the Atlantic States Marine Fisheries Commission
Species
Stock Assessment Method(s)
American eel
None
American lobster
Cohort analysis, egg production per recruit, Delury
Atlantic menhaden
VPA (basic and separable)
Atlantic sturgeon
Stock recruitment, egg recruitment
Black sea bass (with MAFMC)
VPA (ADAPT and ICA)
Bluefish (with MAFMC)
VPA (ADAPT, Cagean or ICA), tagging
Croaker
None
Northern shrimp
Abundance indices
Red drum (with SAFMC)
VPA (separable)
Scup (with MAFMC)
VPA (ADAPT)
Sea herring
VPA (ADAPT, ICA)
Shad and river herring
Stock recruitment
Spanish mackerel
VPA (ADAPT)
Spot
None
Spotted seatrout
None
Striped bass
Spawning stock biomass, stock recruitment
Summer flounder (with MAFMC)
VPA (ADAPT)
Tautog
VPA (ADAPT, Laurec-Shepard, ESA), catch curves, tagging
Weakfish
VPA (ESA)
Winter flounder
VPA (ADAPT)
NOTE: ADAPT = Adaptive approach (age-structured); ESA = extended survivors analysis; ICA = integrated catch analysis; MAFMC = Mid-Atlantic Fishery Management Council; SAFMC = South Atlantic Fishery Management Council; VPA = virtual population analysis.
Lack of information for stock identification may affect appropriateness of stock assessment models applied to various species.
There is need for fisheries-independent data in stock assessment modeling, particularly as tuning indices for VPA analyses.
Relatively simple models may overlook important parameters that the model is not robust to; i.e., sensitivity to changes in catchability.
Little data is available on the functional relations among co-occurring exploited species and effects of fishing on shifts in ecological relations.
Models used to forecast how management actions will change F do not always take into account economic and social factors.
The quality of the input data affects the precision of the assessments.
Pacific States Marine Fisheries Commission (PSMFC)
There are fisheries on the West Coast that do not have the basic population data necessary to allow adequate assessment modeling. The thresher shark fishery is one example of a fishery that is being managed very conservatively due to the lack of funding for adequate assessments. We believe it is critical that efforts be initiated to develop the databases necessary to manage these fisheries.
Rockfish are targeted by both commercial and recreational fisheries off the West Coast. There has been concern, coast-wide, regarding the management of nearshore rockfish. These concerns have been discussed on a regional basis by the Canada-U.S. Groundfish Committee. This committee listed the following concerns.
The lack of biological information and abundance for many nearshore rockfish species
The generally poor track record of rockfish management coast-wide
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TABLE H.2 Stock Assessment Methods Used by the State of Oregon to Manage Its Fisheries
Species Name
Stock Assessment Model
Comments
Pink shrimp
No formal assessment. Stock status is monitored using a retrospective, area-based index of recruitment.
Managed by season and aggregate size limit
Red sea urchin
No formal assessment. Stock status is monitored using retrospective indices of size distribution and abundance.
Managed by size limit and limited entry
Dungeness crab
None
Managed by season, sex, and size limit
Pacific herring, Yaquina Bay
No formal assessment. Spawn deposition surveys conducted to establish harvest guidelines.
Managed by harvest guideline, season, limited entry
The notable difficulty in managing nearshore species
The longevity and vulnerability to over-exploitation associated with these species even when some biological parameters are known
Rockfish are managed by the Councils and the states. Most species occur in fisheries managed by different jurisdictions making it difficult to fully assess the populations and fishery impacts.
Another issue is the lack of total catch information in many fisheries. Landing tickets give managers information on those species landed, but very limited data exist for West Coast fisheries total catch. Regulatory and economic discards are virtual unknowns. We believe an effective observer program is essential for the future health of these fish stocks and their attendant fisheries. A voluntary pilot program funded by the West Coast trawl industry is an important start to gather this data. Two states in the region provided information about the stock assessment methods they use: Oregon (Table H.2) and Alaska (Tables H.3 to H.5).
Alaska Department of Fish and Game (ADF&G)
Often we fail to recognize that most samples taken for stock assessment are not random samples. Statistical models behind estimates from stock assessment are built with the concept of samples being representative of populations because these samples were randomly drawn. In stock assessment, samples are almost never randomly drawn. More diagnostic testing should be built into stock assessments to determine if our non-randomly drawn samples are, or are not, representative.
Extrapolation of results from VPA (virtual populations analysis) to manage fisheries in the current year is a poor substitute for annual surveys and mark-recapture experiments. Since these extrapolations reflect past, not current information, results of VPA lag behind actual trends in abundance. Ancillary information from indices such as mean CPUE (catch per unit effort) to compensate adds another layer of assumptions and considerable danger.
Sampling (handling) fish affects their subsequent behavior in ways that could bias stock assessments based on that behavior. Again, more diagnostics are needed to determine influences of handling.
The lack of age structures for most shellfish species has thwarted the development of assessment models for years. For the past three years, ADF&G has focused on development of length-based methods for shellfish stock assessments under a range of data situations (e.g., trawl survey, pot survey, no survey). During the next few years ADF&G will continue to apply these methods to various stocks around the state. ADF&G also plans to
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TABLE H.3 Methods Used to Assess Alaska Shellfish
Species Name/Area
Stock Assessment Model
Comments
Red king crab
Southeast Alaska
Catch-survey analysis (CSA)
For CSA methods, see Collie and Kruse (in press)
Bristol Bay
Length-based analysis (LBA)
For LBA methods, see Zheng et al. (1995a,b)
Kodiak
Prince William Sound, Cook Inlet, Alaska Peninsula, Pribilof Islands, Norton Sound.
CSA, trawl survey, area-swept estimator Trawl survey, area-swept estimator
Plans: LBA
Plans: CSA (historical pot surveys) and LBA (ongoing trawl surveys)
Adak
None
Plans: catch-length analysis (CLA) - see Zheng et al. (1996) for methods
Blue king crab
St. Matthew and Pribilof Islands
Trawl survey, area-swept estimator
CSA in progress
Prince William Sound
None
CPUE index from experimental fishery
Golden king crab
Southeast Alaska, Prince William Sound, Dutch Harbor, Adak
None
Plans: GIS analysis of fisheries with on-board observer data
Tanner crab
Southeast Alaska
None
CPUE model used to project attainment of fixed quota
Cook Inlet, Kodiak, Alaska; Peninsula, Bering Sea
Trawl survey, area-swept estimator
LBA in progress for Bering Sea, LBA planned for Kodiak
Snow crab; Bering Sea
Trawl survey, area-swept estimator
Needs: growth and M estimates
Hair crab
Bering Sea
Trawl survey, area-swept estimator
Needs: growth and M estimates
Dungeness crab
Southeast Alaska, Yakutat, Kodiak, Alaska Peninsula
None
CLA possible in future
Prince William Sound, Cook Inlet
Pot survey, index of abundance
CSA possible in future
Pink shrimp
Cook Inlet, Kodiak, Alaska
Trawl survey, area-swept estimator;
LBA in progress for Cook Inlet
Peninsula
None
CLA possible in future
Southeast Alaska
Weathervane scallop
Prince William Sound, Cook Inlet
Dredge survey, area-swept estimator
Plans: develop age-structured model
Yakutat, Kodiak, Dutch Harbor, Bering Sea
None
Plans: GIS analysis of onboard fishery observer data
Sea cucumber
Southeast Alaska
Dive survey, surplus production model
Needs: growth and recruitment
Elsewhere
None
estimates
Needs: sampling, basic biological information
Sea urchin
Southeast Alaska
Dive survey, surplus production model
Needs: growth and recruitment
Elsewhere
None
estimates
Needs: sampling, basic biological information
Intertidal clams
Cook Inlet (Kachemak Bay) Elsewhere
Transect surveys
None
Plans: develop age-structured model
Miscellaneous other shellfish species (crabs, shrimps, clams, etc.)
Statewide
None
Needs: basic biological information and sampling programs
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develop fishery-based assessments for fisheries with onboard observers in a GIS framework. Despite progress, stock assessments are not possible for the majority of Alaskan shellfish stocks due to a lack of basic biological information and funds for sampling programs.
Budgets are declining while the complexity of and conflicts with the fishery management process are increasing. This situation will inevitably lead to a reduction in the quality of stock assessment data. This problem is most acute for stocks where fisheries are developing.
Gulf States Marine Fisheries Commission (GSMFC)
The stock assessment team of the Gulf States Marine Fisheries Commission has reviewed the documents provided by your office and generally offer complete concurrence with the thirteen points raised by the Atlantic States staff. Three comments (which to me represent emphasis) forwarded by GSMFC stock assessors were:
Environmental Concerns. Natural climatological phenomena obviously play a role in success/failure of fishery management measures. While this is taken for granted in a functional sense, there is no practical way to account for these influences in current modeling practices. (Related or similar to ASMFC #5.)
Human Dimensions. Almost totally lacking in stock assessment proceedings is the reactive capability of the fishers. It is typical for fishers to act or react unpredictably to management measures. (Related or similar to ASMFC #12.)
Local vs. Regional Management. Spotted seatrout is an example. While regional management is desirable from an interstate transport perspective, status of local trout stocks can be drastically different within a relatively small geographic region. Regional managers may know very little about the condition of these local stocks. (Imbedded in ASMFC #s, 2, 5, 6, 8, 9, 10, and 13.)
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TABLE H.4 Methods Used to Assess Pacific Salmon
Species Name/Area
Harvest Policy
Stock Assessment Methods
Chinook salmon
Southeast Alaska
Preseason quota based on constant harvest rate applied to preseason forecasted abundance with Pacific Salmon Commission Chinook Technical model
Cohort analysis of coded wire tag recoveries from hatchery indicator stocks; wild stock escapement enumeration with weirs, mark-recapture, aerial surveys, foot surveys
Yakutat
Fixed escapement goal
Weir counts
Copper River
Fixed escapement goal
Aerial survey counts
Upper Cook Inlet
Limited directed commercial fishing, reduce bycatch, sport fisheries managed for fixed escapement goals
Sonar counts, weir counts, aerial surveys
Kodiak/Chignik
No directed commercial fishing, fixed escapement goal
Aerial surveys, weir count
Bristol Bay
Fixed escapement goal
Sonar counts, aerial surveys
Kuskokwim River
Commercial fishery quota ranges
Test fishery catches, commercial fishery CPUE
Yukon River
Commercial fishery quota ranges
Test fishery catches, commercial fishery CPUE, mark or recapture, postseason run reconstruction
Coho salmon
Southeast Alaska
Scheduled closures of troll fishery based on CPUE of inside fisheries and early escapement; postseason evaluation of escapement relative to goals and harvest rates for indicator stocks
Fishery CPUE, indicator stock assessments (weir counts, mark-recapture of juveniles, exploitation rates CWT marking), fishwheel catches, aerial surveys
Yakutat
Fixed escapement goals
Weir counts, aerial surveys
Copper, Bering River
Fixed escapement goals
Weir counts
Upper Cook Inlet
Stocks in Northern/Central District systems caught incidental to directed sockeye fishery.
Fishery CPUE, limited weir count
Directed Westside set net fishery limited to two openings per week and reduced if CPUE low
Kodiak
Fixed escapement goal
Aerial survey, weir count
Chignik
Fixed escapement goal
Aerial survey, weir count
Alaska Peninsula
Fixed escapement goal
Aerial survey, weir count
Bristol Bay
Fixed escapement goal
Sonar count, aerial survey
Kuskokwim River
Reduced fishing periods when run strength is weak
Test fishery CPUE
Yukon River
Catch incidental to fall chum fishery, stock not fully exploited
Test fishery CPUE, sonar count
Pink salmon
Southeast Alaska
Fixed escapement goals
Aerial survey
Prince William Sound
Fixed escapement goals
Aerial survey, hatchery stock identification based on CWT
Lower Cook Inlet
Fixed escapement goals
Aerial survey
Kodiak
Fixed escapement goals
Aerial survey
Chignik
Fixed escapement goals
Aerial survey
Alaska Peninsula
Fixed escapement goals
Aerial survey
Bristol Bay, Norton Sound
Production highly variable, markets not well developed
None
Chum salmon
Southeast Alaska
Generally catches incidental to pink salmon, except for hatchery terminal harvest
Aerial surveys, poor quality due to presence of pink salmon
Prince William Sound
Generally catches incidental to pink salmon, except for hatchery terminal harvests
Aerial surveys, poor quality due to presence of pink salmon
Kodiak
Generally catches incidental to pink salmon, except for hatchery terminal harvests
Aerial surveys, poor quality due to presence of pink salmon
Alaska Peninsula
Generally catches incidental to pink salmon
Aerial surveys, poor quality due to presence of pink salmon
Bristol Bay
Harvests incidental to directed sockeye fishery
Nushagak sonar, aerial survey
Kuskokwim River
Fixed escapement goal
Sonar count, test fishery catches, weir counts, aerial survey
Yukon River
Fixed escapement goals, in river allocation plan, subsistence priority summer run fishery is market limited
Sonar count, test fishery catches
Norton Sound
Fixed escapement goal, large-run fisheries are market limited
Lower counts, aerial surveys, weir counts
Kotzebue Sound
Fixed escapement goal
Sonar count, aerial survey, test fishery catches
Sockeye salmon
Southeast Alaska
Fixed escapement goals, interception fishery limited by quota
Weir count, mark-recapture
Yakutat
Fixed escapement goal
Weir count, aerial survey
Copper/Bering River
Fixed escapement goal
Sonar count, aerial survey
Upper Cook Inlet
Fixed escapement goal
Sonar count, test fishery catches
Kodiak
Fixed escapement goal
Weir count, test fishery catches
Chignik
Fixed escapement goal
Weir count, test fishery catches
Alaska Peninsula
Fixed escapement goal, June interception quota set on Bristol Bay sockeye preseason forecast and chum cap
Weir count, aerial survey, test fishery catches
Bristol Bay
Fixed escapement goal
Lower count, sonar count, aerial survey, test fishery catches
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TABLE H.5 Methods Used to Assess Pacific Herring
Area
Harvest Policy
Stock Assessment Methods
Southeast Alaska
Fixed harvest rate with threshold
Age-structured analysis tuned to biomass estimated with spawn deposition surveys
Prince William Sound
Fixed harvest rate with threshold
Age-structured analysis tuned to biomass estimated with spawn deposition surveys, aerial surveys
Lower Cook Inlet
Quota based on historical catches that maintained stable abundances; quota increments or decrements based on in-season abundance indices
Aerial surveys
Kodiak
Quota based on historical catches that maintained stable abundances; quota increments or decrements based on in-season abundance indices
Aerial surveys
Bristol Bay
Fixed harvest rate with threshold
Aerial surveys
Kuskokwim Bay
Quota based on historical catches that maintained stable abundances; quota increments or decrements based on in-season abundance indices
Aerial surveys
Norton Sound
Quota based on historical catches that maintained stable abundances; quota increments or decrements based on in-season abundance indices
Aerial surveys
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TABLE H.6 Stock Assessment Methods Used by the Gulf States Marine Fisheries Commission
Species Name
Stock Assessment Methods
Comments
Gulf sturgeon
None—coast-wide annual population estimate in some Florida rivers
Listed as threatened; habitat and population status largely unknown
Striped mullet
VPA (GXPOPS, Florida) SSBR, SPR coast-wide
Gulf menhaden
VPA (basic and separable)
Black drum
VPA
Length cohort analysis
Striped bass
Limited SSBR
Tagging studies
Oyster
None
Local annual predictive models
Blue crab
None
Stock assessment to be attempted for 1997 FMP revision
Spanish mackerel
Surplus production yield per recruit
VPA—Florida
Gulf shrimp
Indices of abundance
Spotted seatrout
VPA
SPR
FMP to be published in 1997
Flounder
In progress (VPA, SPR)
FMP to be published in 1997
NOTE: FMP = fishery management plan; SPR = spawning biomass per recruit; SSBR = spawning stock biomass per recruit; VPA = virtual population analysis.
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