AESF ss new 011409 part b

SUPPORTING STATEMENT
ANNUAL ECONOMIC SURVEY OF FEDERAL SOUTH ATLANTIC SHRIMP
PERMIT HOLDERS
OMB CONTROL NO. 0648-xxxx

B.

COLLECTIONS OF INFORMATION EMPLOYING STATISTICAL METHODS

1. Describe (including a numerical estimate) the potential respondent universe and any
sampling or other respondent selection method to be used. Data on the number of entities
(e.g. establishments, State and local governmental units, households, or persons) in the
universe and the corresponding sample are to be provided in tabular form. The tabulation
must also include expected response rates for the collection as a whole. If the collection has
been conducted before, provide the actual response rate achieved.
The population of interest is all vessels fishing for penaeid and rock shrimp in the federal waters
of the South Atlantic, i.e. off the States of North Carolina, South Carolina, Georgia, and Florida,
during one calendar year. An excellent sampling frame is readily available for this and future
survey efforts, because vessels shrimping in the South Atlantic and Gulf are required to have a
federal permit. Their contact information should be up-to-date due to the annual permit renewal
process. Due to the overlap with the federal Gulf shrimp permit population, the South Atlantic
survey will be administered together with the Gulf survey. As a result, the effective population is
all federally permitted shrimp vessels in the southeast region. For the 2009 survey effort
(collecting 2008 annual data), the sampling frame will consist of all fishermen holding at least
one of four federal shrimp permits at any time during 2008.
As of October 2008, we estimate this total population to be 2,320 vessels. Of these we propose to
sample 861 vessels in order to arrive at approximately 771 completed surveys based on an
expected overall response rate of 90% (the response rate achieved in the Gulf). 1 Due to the
management and political importance attributed to delineation by state, we will stratify the total
population of federal shrimp permit-owning vessels by state. Within each stratum we will
randomly sample vessels in proportion to each stratum’s weight in the total population. By
sticking to a simple, straightforward design, we hope to avoid many potential problems.
Currently, the closest estimate of the final sampling frame consists of 2,320 vessels. Table 1
below breaks down this preliminary sampling frame into the strata, lists the permits held, offers
some descriptive data for the vessels in each, and generates the tentative number of respondents
sampled and surveys completed in each. Of the total sampling frame, 1,626 vessels (70% of the
2,320) hold only a Gulf shrimp permit and thus represent the dominant group (note: this
information cannot be deduced from the table).There is significant variation within the industry
across several variables, but none seems to further divide the population into discrete groups
(offering no advantage of further stratification). These numbers are unlikely to change much by
early 2009, when the actual sampling frame and sample will be generated. The actual number of
permit holders in the fishery might change a little due to new entrants (the South Atlantic
penaeid permit and rock shrimp permit (Carolinas zone) are open access permits), owners and
vessels leaving the fishery (permits non-renewed or terminated), or changes in vessel ownership
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Even though the data collection will be mandatory, a 100% is almost always impossible. Some permit holders will
be unreachable, and others, who do not plan to renew their permit, are unlikely to voluntarily submit a survey.

1

and State of registration. The final sampling frame will use all the information available just
prior to the survey implementation.
Since much of the above sample will be directed toward Gulf shrimp permit holding vessels,
which are already being surveyed by a separate data collection (OMB Control No. 0648-0476),
the actual additional sample due to adding those holding South Atlantic permits only, is only 160
surveys [711 vessels sampled for the Gulf survey alone; 861 vessels sampled for the combined
surveys]. Among the South Atlantic vessel population sampled will be approximately 230 South
Atlantic penaeid shrimp permit holders, 99 rock shrimp permit holders (open access), and 57
rock shrimp endorsement holders. Finally, the Gulf survey has already sampled about 63% of the
Gulf population over the last two years, including some vessels that have South Atlantic permits.
This will be taken into account during the sampling procedure.
The response rates for the Annual Economic Survey of Federal Gulf Shrimp Permit Holders have
been above 90% in 2007 and 2008.
2. Describe the procedures for the collection, including: the statistical methodology for
stratification and sample selection; the estimation procedure; the degree of accuracy
needed for the purpose described in the justification; any unusual problems requiring
specialized sampling procedures; and any use of periodic (less frequent than annual) data
collection cycles to reduce burden.
We will then stratify the population by State as this is a policy relevant variable. We will then
randomly sample in each strata proportional to each strata’s weight in the population (with the
help of an advanced statistical program). In 2009, we will sample approximately 37% of the
population (see also Table 1). The very tractable proportional random sampling approach should
require only simple adjustments to the inclusion probabilities used for the estimation of
population means and other aggregate statistics (if non-response is significant and skewed across
the strata).
The owner of each vessel selected will be contacted by mail early in 2009, first by a selection
letter, followed by the survey package. The package will contain a cover letter, information
material, instructions, the two page survey instrument and a return envelope. They will be asked
to return the completed survey instrument to us in the enclosed, pre-paid envelope. If no
response is received by April 30, up to two further letters will be sent (including additional
survey instruments). We will also attempt to contact the non-responders by phone and urge them
to return the survey. Information will not be collected during the phone call, and a further survey
instrument will be sent – by mail or email – if requested.
After data entry, verification and cleaning, descriptive statistical analysis will be conducted on
the relevant variables collected (costs and profits). Results will be reported by state and by other
relevant post-stratifications (such as size of operation). The accuracy for the population level
totals and means of the important variables should exceed the standard +/- 10% confidence
interval at a 95% significance level. This level of accuracy would be the best ever collected on
these variables in the South Atlantic shrimp fishery. Given the overall uncertainty inherent to
policy assessments of economic conditions in fisheries and given the quality and accuracy of
other data used, the standard accuracy should suffice. The accuracy of the results for
subpopulations (>100 observations), such as rock shrimp permit holders, is unknown at this time.
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Since the method being employed is new in this fishery; statistically meaningful data is urgently
needed by the Council; and developments in this fishery have recently been occurring fast and
are leading to large economic impacts, this data collection will be repeated annually for the first
two or three years. The use of periodic instead of annual collection will be considered in the
future. The burden on the public will depend on how frequently significant changes occur in this
industry. Optimally, an annual survey with an adaptive sampling design could minimize this
burden and yet retain the flexibility to generate timely and accurate data. Such advantages would
need to be weighed against the administrative complexity and the required resources.
3. Describe the methods used to maximize response rates and to deal with non-response.
The accuracy and reliability of the information collected must be shown to be adequate for
the intended uses. For collections based on sampling, a special justification must be
provided if they will not yield "reliable" data that can be generalized to the universe
studied.
The central approach to maximizing the response rate is to make answering a very concise and
simple survey a requirement for future permit renewal. The first cover letter will politely
emphasize this point. The second and third reminder letters will be more explicit. The telephone
call will also explain the consequences of not complying. The call has the further advantage of
being a different mode of contact and should discover non-response due to an incorrect address.
Given the potential loss of permit, we expect compliance from all fishermen wanting to continue
to fish for shrimp in federal waters. The behavior by those who have left the fishery by the time
of the survey, or are planning to leave it before their current permit expires, will not be
influenced by the implicit threat. Since the data will be used primarily for assessments and
predictions about future developments, under-reporting by individuals leaving the fishery is less
problematic.
A good sampling frame, with annually updated contact information (through the ongoing permit
renewal), will help to reduce the non-contact component of non-response. If necessary due to
low response, at the conclusion of the survey, we will contact port agents (local federal
employees who collect data and report from a limited area) and ask them for any information on
non-responding vessels/individuals. Should non-response be a significant factor, we might even
ask port agents to inquire themselves, and/or we will debrief a few (<10) individuals about
reasons for not responding in order to establish potential non-response biases.
Beyond the above, we will take every action available to us to facilitate completing and returning
the survey by the fishermen. General survey design techniques (Dillman method) and experience
from the previous surveys will guide us. Noteworthy actions include:
•
•
•

Timing of the survey during the slow shrimp fishing season (winter and spring) and
coinciding with tax time, when business records are being consulted and financial
concerns are “top of mind.”
Conducting outreach in advance of the survey, including on NMFS and Council websites
and through meetings, radio, shrimp association newsletters, and the grapevine.
Disseminating together with the survey effort-specific outreach material (see figure 1 for
an example).
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•

Using plain language and translating the survey into “language” spoken by South Atlantic
shrimp fishermen.

The statistical design and size of this sample survey will allow for valid generalizations of the
results to the population and larger subpopulation levels. The anticipated accuracy of the results
is discussed in more detail in the last question (Part B, Question 2).
4. Describe any tests of procedures or methods to be undertaken. Tests are encouraged as
effective means to refine collections, but if ten or more test respondents are involved OMB
must give prior approval.
We are not testing any procedures or methods. We have drawn extensively on the experience
generated by the very similar and successful annual cost data collection effort in the Gulf shrimp
fishery (OMB Control No. 0648-0476).
5. Provide the name and telephone number of individuals consulted on the statistical
aspects of the design, and the name of the agency unit, contractor(s), grantee(s), or other
person(s) who will actually collect and/or analyze the information for the agency.
Individual consulted on the statistical aspects of the design:
James R. Waters, Ph.D.
National Marine Fisheries Service
Southeast Fisheries Science Center
Beaufort Laboratory
(252) 728–8710
Persons who will actually collect and analyze the information:
Christopher Liese, Ph.D.
National Marine Fisheries Service
Southeast Fisheries Science Center
Social Science Research Group
(305) 365-4109
Michael D. Travis, Ph.D.
National Marine Fisheries Service
Southeast Regional Office
Social Science Branch
(727) 551-5722

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Table 1: Sampling Frame, Sampling Strata, Population Characteristics, Response Rate and Sample Size

Population

Permits/Percentage of
Population by Permit Type
SPA

1

RS

3

Vessel Characteristics (Length, HP and Year
averaged by state and then per column)

2

4

RSE

GMSP

Length

HP

Year

Steel Hull

Freezer

Sample

Response
Rate

E(Completed)

NC

177

96%

43%

10%

24%

62

457

1982

37%

14%

66

0.9

59

SC

56

100%

13%

2%

7%

59

409

1975

13%

18%

21

0.9

18

GA

105

94%

12%

10%

5%

57

389

1974

12%

15%

39

0.9

35

FL

391

46%

17%

14%

80%

56

386

1980

25%

44%

145

0.9

130

AL

148

34%

35%

34%

93%

66

492

1987

68%

57%

55

0.9

49

MS

148

9%

5%

3%

100%

71

574

1988

82%

48%

55

0.9

49

LA

483

2%

1%

0%

100%

64

489

1987

77%

27%

179

0.9

161

TX

759

3%

1%

1%

100%

72

537

1984

88%

71%

281

0.9

252

Other

53

42%

51%

15%

57%

71

594

1987

72%

32%

20

0.9

18

Total

2320

27%

11%

7%

83%

65

487

1984

64%

46%

861

Permit Type Count:

619

265

154

1919

Sample by Permit:

230

99

57

711

1

SPA: South Atlantic penaeid shrimp permit (open access).
RS:
South Atlantic rock shrimp permit (open access).
3
RSE: South Atlantic rock shrimp permit (limited access).
4
GMSP: Gulf of Mexico shrimp permit (limited access).
2

5

771

Figure 1: Example of Information Material (draft)

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Table 2: Example of the Presentation of Results

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