The Jolly and Hampton (1990) estimator is often used to calculate mean pelagic animal densities and associated variances.
jhF(transectLength, transectMeanDen, transectName = NULL, svyName = NULL, area = NULL)
| transectLength | vector of parameter lengths |
|---|---|
| transectMeanDen | transect weighted mean densities. See details. |
| transectName | =NULL Optional character vector of transect names. |
| svyName | =NULL Optional character variable of survey names. Must be used if the jhMultipleStrataF function is used to estimate mean and variance across multiple strata. |
| area | =NULL Optional character variable of the survey or stratum name. Must be used if the jhMultipleStrataF function is used to estimate mean and variance across multiple strata. |
two element list.
The transectMeanDen In the case of acoustic data, each element (areal density value) is multiplied by the integration interval (along transect) length. The distance multiplication must take place outside of this function.
Jolly, G. M., and Hampton, I. 1990. A stratified random transect design for acoustic surveys of fish stocks. Canadian Journal of Fisheries and Aquatic Sciences, 47: 1282-1291.
# NOT RUN { tLengths=c(77.67,78.28,78.91,80.22,78.07,73.60,78.53,78.39,78.52,79.48) denV=c(158.03,159.50,96.41,133.86,246.60,243.95,122.65,276.92,59.83,89.90) svyA=80*100*1e6 jhF(transectLength=tLengths, transectMeanDen=denV, transectName=NULL,svyName='test',area=svyA) # }