Terceiro: The statistical properties of recreational catch data off the northeastern U.S. coast 



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all directed trips including zero catches and for positive 



catches only. 



Simulated recreational fishery catch rates 



To isolate the consequences of possible model misspecifica- 

 tion in deriving standardized indices of abundance, nega- 

 tive binomial distributions with characteristics like those 

 of MRFSS recreational catch-per-trip distributions were 

 simulated by using the SAS RANTBL function (SAS, 2000). 

 The simulated distributions were arranged to provide con- 

 tinuously decreasing, continuously increasing, and peaked 



(increasing to a peak and then decreasing) trends in an 

 11-year time series of catch per trip. For the decreasing 

 trend, the simulation procedure began with year 1 set at 

 a mean catch per trip = 3.0, maximum catch per trip of 50 

 fish per trip, and variance = 81.0, which are characteristic 

 of the MRFSS catch-per-trip distributions for all species 

 (Table 1). For year 1, this combination of mean and vari- 

 ance provided a maximum likelihood estimate of the nega- 

 tive binomial dispersion parameter, k, of 0.23. 



The vector of expected probabilities of catch per trip 

 for these initial moments, assuming a negative binomial 

 distribution, was then used to randomly generate 1000 



