Review of Recreational Fisheries Survey Methods (2006) / Chapter Skim
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2 Current Situation and Problems in Effort and Catch Estimation
2 Current Situation and Problems in Effort and Catch Estimation
Pages 31-56
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From page 31... ...
. Survey programs must also consider design characteristics needed to address the requirements for information on indices of relative population abundance, biological sampling of fish species, and related parameters concerning economics and angler attitudes.
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From page 32... ...
Therefore, the Marine Recreational Fisheries Statistics Survey (MRFSS) uses a hybrid approach in which dockside intercept surveys are used to estimate CPUE and conduct biological sampling, and catch and telephone interviews are used to estimate effort.
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From page 33... ...
Other potential biases within the sampling design can be estimated using the existing data, but these analyses have not been conducted. Inefficiencies arising from overcoverage in the list frame for effort estimation result in low precision of estimates and higher cost than
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From page 34... ...
The accesspoint intercept survey used within the MRFSS and component programs is also an incomplete list frame. Even though the intercept sample sites may be geo-referenced, they are chosen from a master list of documented access sites (e.g., boat ramps, docks, piers)
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From page 35... ...
Finally, the expertise and personnel needed to evaluate and improve the survey design and execution continually are lacking, and methods used to collect and analyze recreational fisheries data have not incorporated evolving statistical methodology or new innovations and technologies that would improve statistical efficiency and reduce costs. A number of regional surveys have been developed in recent years with the aim of addressing some of these problems.
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From page 36... ...
Furthermore, the target species for anglers may be varied and may include species entirely allocated to recreational fisheries, as well as those from mixed recreational and commercial fisheries. The difficulties of covering all fishing modes, access points, and duration of fishing has led to several additional surveys that complement the basic MRFSS approach.
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From page 37... ...
Anglers who reside beyond this area, but who fish from shore in the survey area, are excluded from the sampling frame.
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From page 38... ...
For-Hire Fishing When anglers go with a guide, charter fishing on boats with crew, or on head boat trips, their participation and removals are estimated through a different framework than that used for private anglers. However, anglers who rent boats for independent, nonguided fishing are captured by the current MRFSS sampling approaches; these waterborne anglers are treated similarly to the private boat anglers discussed above.
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From page 39... ...
Effort in the For-Hire Survey, which measures number of boat trips, number of anglers, and areas fished, is determined from boat directory telephone surveys instead of RDD employed in the MRFSS. Because the list frame is complete, assuming that the directory is kept up to date, the potential bias associated with not collecting effort data from noncoastal county anglers is not an issue as it is with the MRFSS.
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From page 40... ...
Night Fishing In some areas, night fishing is common and creates unique challenges to estimation of catch rates and, to a lesser degree, fishing effort. Effort for night fishing can be estimated through the telephone survey in the same way as for other modes of fishing.
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From page 41... ...
The timeframe for estimation through the MRFSS process (because it takes a long time to accumulate enough fishing households to have an adequate sample size) does not address management requirements consistently, in part due to the inefficient telephone sampling frame for estimating fishing effort.
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From page 42... ...
(this number will be less than 1 since some anglers reside outside the frame, in noncoastal counties, and is estimated from the access survey) : E^ = E^RDD /^RDD In other words, total estimated effort is the corrected effort after adjusting for the proportion included in the sampling frame ^ RDD.
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From page 43... ...
. This also would allow comparison of angler effort levels and perhaps catch rates over time, yielding more precise estimates.
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From page 44... ...
The sample cannot yield information about CPUE from anglers who fish from small public access sites not included on the frame, anglers fishing from private shorelines, or those who leave from private docks. For the sample estimate of CPUE to be unbiased, one must assume that anglers who fish at sites not included on the intercept sampling frame have the same success in fishing and that they target the same species as those who fish at sites that are included on the frame.
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From page 45... ...
(k /ti) = k /t where ti is the number of angler trips at site i in the period, t is the total angler trips, and k is the number of angler trips selected at each site.
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From page 46... ...
With multiple organizations involved, it is difficult to specify and monitor adherence to a common sampling protocol across survey efforts. 2A quota sample defines groups of people who are deemed important to reach, based on information about the target population.
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From page 47... ...
However, this assumption ignores the high hooking mortality rate associated with some fisheries, especially for those species with swimbladders that are caught at significant depths, such as rockfish or grouper. In some instances, mortality on released fish may represent the major mortality factor in total removals.
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From page 48... ...
However, cage experiments would provide only a minimum estimate of mortality and reflect only "physiological" mortality rather than the "ecological" mortality that would be measured through tagging studies. NEW DEMANDS ON RECREATIONAL FISHING DATA This committee identified a number of areas in which designers of sampling programs, data collectors, and users of recreational fisheries data appear to have incomplete communication, mismatched criteria, or other miscommunications.
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From page 49... ...
. In addition, recreational data are now used for many stock assessments.
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From page 50... ...
The time it takes to collect, verify, and calculate fishing effort and catch using conventional survey approaches is too lengthy, even for annual management, if stability in the yearly total allowable catch is desired. Use of Data for Stock Assessments A large mismatch appears to exist between recreational sampling programs and the stock assessment scientists using them.
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From page 51... ...
Scientists using these data may assume that their statistical properties are known and estimable. (More specific problems associated with recreational fisheries data and their incorporation into stock assessments [e.g., the difficulty of measuring which, if any, species are being targeted]
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From page 52... ...
While this is not a problem with the survey methodology per se, increasing understanding and confidence in the programs can be as essential as improving the data itself. The credibility gap arises from several causes, including a belief that alternate data sources are more credible; criticism of the temporal, spatial, group, or taxonomic stratification of the intercept sampling; lack of understanding of statistical methodology; or recognition that the existing sampling frames do not describe the angler population adequately.
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From page 53... ...
CONCLUSIONS AND RECOMMENDATIONS The designs, sampling strategies, and collection methods of recreational fishing surveys do not provide adequate data for management and policy decisions. Unknown biases in the estimators from these surveys arise from reliance on unverified assumptions.
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From page 54... ...
Management decisions are often made at finer spatial and temporal scales than they were earlier, the mix of recreational and commercial fishing has changed for many areas and species, and stock-assessment models now make greater use of data from recreational fisheries. Reallocation of harvest from commercial to recreational sectors has increased the need to gather stock assessment information in greater detail from recreational fisheries sources.
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From page 55... ...
There has been progress in survey programs directed to some targeted fisheries with the implementation of new, tailored surveys; yet, additional improvement is required. There have been several reviews of the national program in the last 10 years, but a more fluid, continuous review and feedback would allow for evolution of the program to meet emerging needs.
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