Juvenile Menhaden Abundance

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Chesapeake Bay Program Indicator Framework

Reporting Level Indicators

Indicator and Data Survey

For each indicator for which you are responsible, please provide the following information.  This information will be made available to the developers of the reports, the reviewers of the reports and by members of the public who may request detailed information about the data used in the reports.  Please refer to the sample for examples of the level of detail that should be provided.

A.  Category/Name/Source/Contact

(1) Category of Indicator

___ Factors Impacting Bay and Watershed Health

___ Restoration and Protection Efforts

___ Watershed Health

_X_ Bay Health

(2) Name of Indicator:  Menhaden Abundance

(3) Data Set Description:  

For what purpose(s) were the data collected? (e.g., tracking, research, or long-term monitoring.)  Tracking and long term monitoring

Which parameters were measured directly? Which were obtained by calculation? Juvenile Menhaden Abundance was measured by beach seine hauls. Proportion of Positive Haul or proportion of seine hauls with menhaden present is calculated (see attached sheet at the end of this survey.).

(4) Source(s) of Data:  Maryland Department of Natural Resources 

Is the complete data set accessible, including metadata, data-dictionaries and embedded definitions?  If yes, please indicate where complete dataset can be obtained.  

NO, data available by contacting the Custodian of the source data.

(5) Custodian of Source Data (and Indicator, if different): Eric Durell MD DNR 

(6) CBP Contact:  Shannon Simpson, NOAA CBO

B.  Communication Questions

(complete either part 1, 2, or 3)

1.  Restoration and Protection Efforts indicators only

(7a) How much has been completed since 1985 (or baseline year)?  How much has been completed since 2000? 

 (8a) How much was done last year? Minor increase 

(9a) What is the current status in relation to a goal? 

(10a) What is the key story told by this indicator? (11a) Why is it important to report this information? 

 (12a) What detail and/or diagnostic indicators are related to this reporting level indicator? (Detail and diagnostic indicators can be spatially-specific, parameter-specific, temporally-specific information, etc.)

2.Bay Health or Watershed Health indicators only

(7b) What is the long-term trend?  (since start of data collection) 

The proportion of positive hauls (PPH) has ranged from 5% to 67 % from 1959 through 2009. The long-term trend has been inconsistent. The periods from 1959-1970 and from 1992-present have shown similar levels where reported values were below 30 percent. The time between 1971 and 1991 showed a marked jump in PPH. 

 (8b) What is the short-term trend? (10-year trend) 

The current 10-year trend shows that juvenile menhaden abundance as measured by PPH has stabilized, although at a level lower than the long-term average.

(9b) What is the current status in relation to a goal? 

There is currently no established goal for this indicator. The current consensus within the menhaden research community still is that there is no Chesapeake Bay specific sub-population of menhaden. So it is still not technically possible to set Bay specific targets or goals for menhaden.  If CBPO establishes any kind of target or goal, it would be scientifically indefensible. 

(10b) What is the key story told by this indicator?  

After a decade of record high abundance beginning in the mid 1970s and a sharp decline through the 1990s, juvenile menhaden abundance has stabilized at a level below the long-term average.  

(11b) Why is it important to report this information? 

Menhaden play a key ecological role in the Bay as an important prey species for top predators such as striped bass, and for their ability to filter the water.  The menhaden fishery is one of the most important and productive on the Atlantic Coast, providing fish meal, fish oil and bait for the blue crab and other fisheries. Indices of menhaden recruitment address how well Chesapeake Bay is serving as a nursery area for the Atlantic menhaden population (a.k.a. coast-wide stock).

(12b) What detail and/or diagnostic indicators are related to this reporting level indicator?   

The Maryland Young of year index for menhaden.

3.  Factors Impacting Bay and Watershed Health indicators only

(7c) What is the long-term trend?  (since start of data collection) 

(8c) What is the short-term trend? (3 to 5 year trend) 

(9c) What is the current status? (10c) What is the key story told by this indicator?  

(11c) Why is it important to report this information? 

(12c) What detail and/or diagnostic indicators are related to this reporting level indicator?  

C.  Temporal Considerations

(13) Data Collection Date(s):  1959- 2009

(14) Planned Update Frequency (e.g. - annual, bi-annual):

(a) Source Data: Annually

(b) Indicator:  Annually

(15) For annual reporting, month spatial data is available for reporting: 


D.  Spatial Considerations

(16) Type of Geography of Source Data (point, line polygon, other): 

Point Data

(17) Acceptable Level of Spatial Aggregation (e.g. - county, state, major basin, tributary basin, HUC): 

Multiple Levels

(18) Are there geographic areas with missing data?    

If so, where?  

All of the state of Virginia

(19) The spatial extent of this indicator best described as:

(a) Chesapeake Bay (estuary)

(b) Chesapeake Bay Watershed: Strategic choice of rivers throughout the watershed

(c) Other (please describe)

Please submit any appropriate examples of how this information has been mapped or otherwise portrayed geographically in the past.

(20) Can appropriate diagnostic indicators be represented geographically?  

E. Data Analysis and Interpretation

(Please provide appropriate references and location of documentation if hard to find.)

There were two options presented to the Living Resources Subcommittee (LRSC).  Those options are presented at the end of this document.  Following the options are the comments received.

(21) Is the conceptual model used to transform these measurements into an indicator widely accepted as a scientifically sound representation of the phenomenon it indicates?  (i.e., how well do the data represent the phenomenon?)  No

(22) What is the process by which the raw data is summarized for development and presentation of the indicator?   

See Review comment below.

(23) Are any tools required to generate the indicator data (e.g. - Interpolator, watershed model)  SAS

(24) Are the computations widely accepted as a scientifically sound?  

See Review comment below.

(25) Have appropriate statistical methods been used to generalize or portray data beyond the time or spatial locations where measurements were made (e.g., statistical survey inference, no generalization is possible)?  Yes

(26) Are there established reference points, thresholds or ranges of values for this indicator that unambiguously reflect the desired state of the environment? (health/stressors only)   

F.Data Quality

(Please provide appropriate references and location of documentation if hard to find.)

(27) Were the data collected according to an EPA-approved Quality Assurance Plan? No 

If no, complete questions 28a – 28d:

(28a) Are the sampling design, monitoring plan and/or tracking system used to collect the data over time and space based on sound scientific principles?  Yes

(28b) What documentation clearly and completely describes the underlying sampling and analytical procedures used.  See


(28c) Are the sampling and analytical procedures widely accepted as scientifically and technically valid?  Yes

(28d) To what extent are the procedures for quality assurance and quality control of the data documented and accessible? 



(29) Are the descriptions of the study or survey design clear, complete and sufficient to enable the study or survey to be reproduced?  Yes

(30) Were the sampling and analysis methods performed consistently throughout the data record? Yes

(31) If datasets from two or more agencies are merged, are their sampling designs and methods comparable? NA

(32) Are uncertainty measurements or estimates available for the indicator and/or the underlying data set?  Yes see below

(33) (Do the uncertainty and variability impact the conclusions that can be inferred from the data and the utility of the indicator?  (see below)

(34) Are there noteworthy limitations or gaps in the data record?  No

G.  Additional Information


(35) Please provide any other information about this indicator you believe is necessary to aid communication and any prevent potential miss-representation.

• “Scientists currently do not produce Chesapeake Bay-specific population estimates of menhaden. Estimates are made on an Atlantic Coast-wide basis. Populations along the Atlantic Coast appear to be healthy, but scientists are concerned about low regional abundances in Chesapeake Bay. The number of juvenile menhaden in Chesapeake Bay has been declining in recent years, with current recruitment levels being about 50% lower than the mid-1980s.  In 2006, Virginia placed a cap on the amount of menhaden that can be harvested annually from the Chesapeake Bay by the commercial fishing industry.  Maryland currently prohibits commercial purse seining , but allows a small commercial pound net fishery.  Since menhaden are an important forage species in the Bay food web, a number of studies are underway to assess their status in the Bay.

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