Chesapeake Bay Fishery-Independent Multispecies Survey (CHESFIMS)

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Chesapeake Bay Fishery-Independent Multispecies
Survey(CHESFIMS)

• T. J. Miller1, C. J. Heyer1, E. D. Houde1 ,A. F.
  Sharov2, B. Muffley2, M. C. Christman3, N.
  Herman3, J. H. Volstad4 and K. Curti1

1. CBL UMCES Solomons, MD 20668 3. Biometry Program UMCP College Park, MD 20742
2. Fisheries Service MDNR Annapolis, MD 21401 4. Versar Corp Columbia, MD 21405
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Background

• The STAC workshop on Multispecies management
  (Houde et al., 1998) concluded multispecies
  approaches to Chesapeake bay fisheries are
  desirable.
• Chesapeake 2000 commits to
• By 2005, develop ecosystem-based management plans
  for targeted species.
• By 2007, revise and implement existing FMPs to
  incorporate ecological, social and economic
  considerations, multispecies fisheries management
  and ecosystem approaches.

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Toward ecosystem-based management

• There is no substitute for good monitoring
  programs of fished species and of key interacting
  species. Modeling evolves from and depends on
  monitoring results, and management depends upon
  an understanding of the status and trends of
  stocks. Fishery-independent surveys to monitor
  resources and obtain biological data, if
  instituted and coordinated throughout the bay,
  would help improve management.

Executive summary of Multispecies Management
workshop report. Houde et al. 1998
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Chesapeake Bay Fish Population
?
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Characteristics of a fishery-independent survey

• A baywide multispecies survey must
• Adequately sample the pelagic, benthic and
  nearshore habitats used by the fish communities
  in Chesapeake bay.
• Accurately estimate relative (or absolute)
  abundance for key species.
• Provide recruitment indices for key species.
• Provide biological characteristics of key species
  including
• Age- and size-structure.
• Diet data by age- and size-class.
• Integrate with existing fishery-independent
  surveys.

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CHESFIMS

• 3 components
• Baywide, broadscale midwater trawl survey.
• Stratified random sample involving two-stage
  stratification (regions upper, mid, lower, and
  transects within regions).
• Samples depths gt 5m, using an 18 m2-midwater
  trawl (6 mm cod end) fished in 10 equal depth
  bins from surface to bottom.
• Builds on existing 1995 2000 NSF-sponsored
  survey (TIES).
• Regional, shoal survey.
• Stratified random sample currently involving 4
  strata.
• Samples depths lt 5m, using a 16 otter trawl
  towed for 6 min.
• Complements and extends existing MDNR and VIMS
  surveys.
• Statistical evaluation.
• Analysis of alternative survey designs to
  optimize final survey design.
• Application of spatial statistical models as to
  develop Baywide abundances.

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Broadscale surveys

• 3 surveys
• Spring
• 4/30 5/5/01
• 31 stations
• 1,473 fish ( 67 kg)
• Summer
• 7/16 7/23/02
• 48 stations
• 81,630 fish (127 kg)
• Autumn
• 9/25 9/29/02
• 15 stations
• 73,619 fish (76 kg)

Upper
Mid
Lower
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Shoal survey

• Spring
• 5/11 6/6/01
• 96 stations
• 2197 fish
• Summer
• 7/10 8/6/01
• 108 stations
• 8,755 fish
• Autumn
• 9/24 10/16/01
• 107 stations
• 4,627 fish

Surveys conducted in four mid-Bay strata, chosen
for compatibility with broadscale efforts, and
with existing surveys
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Summary catch results
Spring
Summer
Autumn
Broadscale
Shoal
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Species diversity
27 20 28 21 26
20
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Distribution of Diversity
Shannon-Weiner Diversity Index
Spring
Summer
Autumn
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Broadscale catch summaries
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Shoal catch summaries
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Analysis of abundance

• Produce robust estimates of relative abundance of
  fish in aggregated categories (e.g.., piscivores,
  benthic, estuarine-dependent, etc.).
• Produce robust estimates of relative abundance of
  individual species using standard survey
  approaches.
• Produce robust estimates of recruitment levels of
  individual species.
• Map the distribution of key species, by life
  stage and habitat.
• Conduct gear comparison tows to allow comparison
  of shoal and broadscale data.
• Using spatial statistical approaches to produce
  robust estimates of integrated baywide abundance.

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Abundance trends
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TIES heritage
others
1995
1996
others
spot
spot
weakfish
weakfish
menhaden
menhaden
alosids
bay anchovy
alosids
bay anchovy
striped bass
striped bass
croaker
croaker
white perch
white perch
others
spot
1997
1998
weakfish
others
menhaden
spot
alosids
weakfish
striped bass
menhaden
bay anchovy
alosids
bay anchovy
striped bass
croaker
croaker
white perch
white perch
others
spot
1999
2000
weakfish
menhaden
others
alosids
spot
striped bass
weakfish
bay anchovy
bay anchovy
menhaden
alosids
croaker
striped bass
white perch
white perch
croaker
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Distribution of abundance
Bay anchovy
Catch.tow-1
Spring
Summer
Autumn
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Biological characteristics
Hogchoker

• Both shoal survey (shown right) and broadscale
  survey can provide data on
• Size and size-at-age
• Recruitment
• Habitat associations
• For a wide range of species

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Diet summaries

• Gut contents flushed, sample split, taxa
  identified, weighed and counted.
• Spring cruise.
• 75 of sampled fishes processed to remove guts.
• 63 of sampled fishes processed for gut contents.
• Summer cruise.
• 11 of sampled fishes processed to remove guts.
• 1 of sampled fishes processed for gut contents.
• Autumn cruise
• To be processed

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Sample diets
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Statistical evaluation

• Comparison of alternative effort allocation
• Design factors calculated for alternative
  analysis
• Survey performance evaluation underway using
  measurements of precision
• Analysis of alternative tow lengths in shoals
  data underway
• Development of spatial modeling

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Progress and plans

• Completed 3 broadscale and 3 shoal survey cruises
  in 2001.
• Analysis of abundance data nearing completion.
• Analysis of biological characteristics of catch
  nearing completion.
• Analysis of dietary data underway.
• Statistical evaluation involving alternative
  sampling strategies and spatial statistical
  approaches underway.
• Broadscale and shoal survey dates selected for
  2002 with expanded coverage.