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Atlantic Menhaden. An update of the issues and science Good science and multiple perspectives. Bob Wood NOAA’s director for the Cooperative Oxford Laboratory. Atlantic menhaden population status and management is a hot topic. http://www.chesbay.org/ (Chesapeake Bay Ecological Foundation).

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Atlantic Menhaden

An update of the issues and scienceGood science and multiple perspectives

Bob Wood

NOAA’s director for the Cooperative Oxford Laboratory


Atlantic menhaden population status and management is a hot topic
Atlantic menhaden population status and management is ahot topic

  • http://www.chesbay.org/ (Chesapeake Bay Ecological Foundation)

“Atlantic menhaden … have the ability to filter a volume of water equal to the entire Chesapeake Bay in less than one day ... However, since there is no quota to limit or control the harvest, this intensive fishery for Atlantic menhaden seasonally depletes the Bay's most valuable living resource.”

  • http://www.menhadenmatter.org (an NGO “alliance”)

“Simply put, striped bass and a number of other predators are competing with the industrial-scale menhaden fishery for food, and they are losing the fight.”

  • http://baytruth.org

“As of now (1/05) there are no laws on the books protecting menhaden.  Omega Protein is free to wipe out this species with no legal consequences or financial risk.”


Localized depletion what does that mean

Localized Depletion is a term that has arisen over …

concerns that the annual abundance and distribution of Atlantic menhaden in Chesapeake Bay is less than optimal with respect to the ecosystem services the population provides: as a forage fish, and as a filter feeder.

“Localized Depletion”(what does that mean?)


  • What do we know - concerns

  • A pronounced and prolonged decline in Atlantic menhaden recruitment to the Bay

  • Chesapeake Bay striped bass “symptoms”

    • Disease/lesions

    • poor condition / “starving” fish


Conceptual model of Atlantic menhaden population dynamics

4) Management

1) Food Web

3) Recruitment

2) The fishery



What we know

  • Menhaden – striped bass trophic linkages

    • signs of stress in the striped bass stock: are they related to declining menhaden abundance?

      • Disease

      • Low weight/length


Ecological importance

40-75% of a young

Striped bass’s diet

piscivorous fishes

forage fishes

Atlantic menhaden

bayanchovy

zooplankton

phytoplankton


menhaden+anchovy

Comprise

a large proportion

of the striped bass

diet

Data pertains to

150 - 450mm striped bass

Provided by John Walter & Anthony Overton


Are striped bass

“menhaden limited” ?

  • Some facts

  • Observations of thin and diseased striped bass appear to be on the rise…some theorize this is related to declining forage.

  • From 1982-95, Striped bass consumption demand increased 8x !

  • Age 3-6 striped bass eat a lot of menhaden in spring & summer

  • As early as 1991, age 3 striped bass had periods of negative growth

  • Dietary energy cost of switching from menhaden to other prey is not very high high


About thin striped bass?

  • studies have shown some # of thin / poor condition striped bass in the population

  • this number varies from year to year

  • Representative sampling to determine the real extent of the problem is VERY difficult

  • Extent and yr-to-yr persistence UNKOWN


Ulcerative Dermatitis Syndrome

Multiple red sores, often coalescing to cover large areas of the dermis.

Multiple pathogens isolated from infected fish, none consistent

Affecting 10 -30%

of fish sampled in

Chesapeake waters


Mycobacteriosis

  • Slow progressing, systemic disease, caused by several species of bacteria of the genus Mycobacterium (1897 – First report of “fish tuberculosis”)

  • Clinical signs may include dermal lesions, pigmentary changes, emaciation, stunted growth, exophthalmia, or no external signs

  • Detected in 50-75% of striped bass (Morone saxatilis) sampled in Chesapeake waters depending on technique

  • Usually results in mortality (in fish), as there is no known cure


Oxford Lab Archives

  • Examination of several hundred archived tissue blocks from 1970 – present

  • Few records prior to late 80’s

  • Wild caught striped bass only

    [research by John Jacobs]

Fishery declared

“recovered”

First reports of unhealthy fish from watermen

Limited Fishery

Re-opened

Fishery Closed



  • About the fishery

  • currently no catch limits [new limits just proposed]

  • very low to no by-catch (efficient catch relative to wasted fish & energy)

  • Coastal fishing grounds in are closed

  • in many northeastern state waters

  • targets age 1-3 (prefer older) which may have limited fish forage potential in Chesapeake Bay

  • Does catch significant levels of age

  • 1’s in some years



Threshold

Threshold

1.18

13.3

Management Benchmarks

Coastal stock meets management objectives and is “healthy” (relative to sustainability)

Fecundity Benchmarks (egg biomass)

Target

Worse

Better

26.6

40.6

Note: Stock values are for 2002

Fishing Mortality (M) Benchmarks

Target

Better

Worse

0.75

0.79


Atlantic menhaden fishing mortality f for ages 2
Atlantic menhaden fishing mortality (F)[for ages 2+]

management threshold

(action if exceeded)

management target


Bubble plot for Atlantic menhaden reduction fishery catch-at-age (Ricker model output)


Recruitment
Recruitment catch-at-age (Ricker model output)


How is recruitment? catch-at-age (Ricker model output)

Not good in Chesapeake Bay and points south

positive trends in northern range

recruitment trends are limiting available

forage for game fish

Climate variability

is a strong candidate

as an important reason


1970 catch-at-age (Ricker model output)

1980

1990

2000

1980

1990

2000

1970

1970

1970

1980

1990

2000

1980

1990

2000

1980

1990

2000

1980

1990

2000

Recruitment

MDNR seine

Upper Bay

VIMS seine

VIMS Bay trawl

1970

1980

1990

2000

VIMS river trawl

Choptank

River

1970

1980

1990

2000

Nanticoke

River

Potomac River

Rappahannock

River

Chesapeake

York

Bay

River

1970

1980

1990

2000

James River

1970


Spring weather conditions appear to influence recruitment catch-at-age (Ricker model output)

Azores-Bermuda high in March =

favorable menhaden habitat & prey conditions for in Chesapeake Bay

Azores-Bermuda

High

warm subtropical air advected northward

Gulf moisture

& storm track

Azores-Bermuda high predicted Atlantic menhaden recruitment

Menhaden recruitment

r-squared = 0.44

20000

Model fitted recruitment

Ricker curve residuals

0

-20000

65

70

75

80

85

90

95


Weather conditions catch-at-age (Ricker model output)

in strong Menhaden recruitment years

Temperature anomalies

Precipitation anomalies

Precipitation inches

Fahrenheit degrees


C catch-at-age (Ricker model output)hesapeake Bay

Anadromous / Shelf Spawner

recruitment pattern (CBASS)

Shelf

Spawners

Common nursery areas -

different spawning behaviors

Annual young-of-the-year abundance

scatter plots

Anadromous

fishes

Anadromous fish

spawning areas

Coastal

shelf spawner

nursery areas


Management
Management catch-at-age (Ricker model output)


Atlantic menhaden management
Atlantic menhaden management catch-at-age (Ricker model output)

Atlantic Menhaden Fisheries Management Plan

Goal:

To manage the Atlantic menhaden fishery in a manner that is biologically, economically, socially and ecologically sound, while protecting the resource and those who benefit from it.


Atlantic menhaden managment
Atlantic menhaden managment catch-at-age (Ricker model output)

  • http://www.asmfc.org/Draft Addendum II to the Atlantic Menhaden FMP

  • Just a few of the stated Objectives:

  • Protect and maintain the Atlantic menhaden stock at levels to maintain viable fisheries and the forage base with sufficient spawning stock biomass to prevent stock depletion and guard against recruitment failure.

  • Maintain existing social and cultural features of the fishery to the extent possible.

  • Protect and maintain the important ecological role Atlantic menhaden play along the coast.

  • Develop options or programs to control or limit effort, and regulate fishing mortality by time or area.


Different stakeholders and user groups
Different stakeholders and user groups catch-at-age (Ricker model output)

Recreational Fishers

Commercial Fishers

Omega Protein

ASMFC

NGO groups

State management agencies

Coastal stock versus Chesapeake Bay

menhaden status


Atlantic menhaden management1
Atlantic menhaden management catch-at-age (Ricker model output)

Draft Addendum II to the Atlantic Menhaden FMP

110,400 metric ton cap vs. 135,000 volunteered by Omega

  • States will be conducting public hearings on the Addendum this summer

  • presents a suite of management options to limit the catch menhaden in both the Chesapeake Bay and coastwide

  • proposes a research program to assess whether localized depletion is occurring and identifies the following research priorities:

    • determine menhaden abundance in the Chesapeake Bay

    • determine estimates of menhaden removal by predators

    • evaluate the rate of exchange of menhaden between the Bay and coastal systems

    • conduct larval studies to determine recruitment to the Bay.


ASMFC Expert panel catch-at-age (Ricker model output)Consensus

(excerpts from ASMFC special report 83)

  • There may be a relative imbalance between the prey needs of an increased striped bass population and a decreased abundance of menhaden juveniles (age zeros and ones) in Chesapeake Bay.

  • The abundance of Atlantic menhaden in Chesapeake Bay remains unknown.

  • There is an ongoing concern of the decade-long decline in recruitment in Chesapeake Bay.


  • Brief Conclusions catch-at-age (Ricker model output)

  • We have reason to be concerned

  • Stock assessments seem to rule out a problem with spawning stock biomass

  • Recruitment has been declining for decades

  • - env’l forcing appears to be influential

  • Striped bass population is showing signs of stress


ASMFC Expert panel catch-at-age (Ricker model output)Advice

(excerpts from ASMFC special report 83)

  • Time and space closures/openings have potential as a management tool.

  • Develop reference points specific to Chesapeake Bay

  • Need to quantify predation mortality and produce estimates of abundance of menhaden to develop ecologically based reference points

  • Confront the need and potential mechanisms for management that cross single species management boundaries.

  • Establish values and goals for population utilization that acknowledge ecosystem services and fisheries support provided by the menhaden population.

  • Investigate the issue of low recruitment in the Chesapeake Bay and what is causing it.


The latest developments catch-at-age (Ricker model output)

(as of March 10, 2005)

  • The ASMFC’s “localized depletion” workshop report (ASMFC special report 83)

  • ASMFC Atlantic Menhaden Plan Addendum II

[ http://www.asmfc.org/speciesDocuments/menhaden/reports/menhadenWorkshopReportDec04.pdf ]

  • “options to limit the catch of menhaden, including restricting the Chesapeake Bay purse seine harvest to no more than 110,400 mt annually in 2006 and 2007”

  • “initiating a research program to … assess whether localized depletion is occurring in the Bay”


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