Calibrating Charter Boat Fishing Effort Estimates Across Survey Changes in a Time Series

The Marine Recreational Fishery Statistics Survey (MRFSS) was established by the National Marine Fisheries Service (NMFS) in 1979 to produce annual estimates of catch and effort by the marine recreational fisheries of the US.  In the traditional MRFSS methodology, data were collected by a telephone survey of households in coastal counties (CHTS) and by interviewing anglers at fishing access sites.  It was acknowledged that the estimation of effort for the charterboat sector was difficult due to the low incidence of this type of fishing trips by households contacted in the CHTS. To reduce the effect of small sample sizes on charterboat effort estimation, data from a 5 year period were combined to produce effort estimates. Pooling data produced more reliable estimates of effort, but this approach tended to mask inter-annual trends.  To improve the effort estimates of charterboat anglers, a new survey protocol using a list-based sampling frame and weekly telephone calling of charterboat operators was designed, tested, and implemented.  The NMFS concluded that this For-Hire Survey (FHS) produced significantly more efficient, precise, and credible charter angler effort estimates than the traditional MRFSS method. The FHS was officially adopted as the  charterboat method in the Gulf of Mexico in 2000 and expanded to the Atlantic Coast in 2004.  A time series of annual landings useful for stock assessments and management purposes requires the use of conversion factors to adjust effort estimates obtained by MRFSS prior to 2000 on the Gulf Coast and 2004 along the Atlantic Coast.  These conversion factors were generated from overlapping survey results obtained from the FHS and the CHTS in 2000-2009 along the southeast Atlantic Coast and the Gulf of Mexico using a regression technique. The adjusted effort levels were applied to the catch-rate data obtained by the MRFSS angler intercept survey to produce an adjusted time series of annual catch and landings estimates per species.