We used the following approach to evaluate the use of a CUFES in the estimation of daily egg production.
This survey for Pacific sardine employed a new survey design with the CUFES and the California vertical tow (CalVET, see below) (Smith et al.
This cruise was used as a standard for comparing DEPM surveys with and without the CUFES.
The CUFES was installed midship on the NOAA vessel David Starr Jordan onto the intake pipe over the side of the vessel; it extended 3 m below the water surface (see illustration in Checkley et al.
The density of eggs taken in the CUFES was expressed as the number of eggs taken per minute.
Conversion of CUFES egg density to full-water-column abundance and distribution of egg stages
Egg counts from 91 paired samples collected with the CUFES and CalVETs during leg 1 of the 1996 survey (Table 1) were used to derive a conversion factor from eggs/minute of CUFES sample to CalVET catch (R).
08) from 110 pairs of CalVET and CUFES of which at least one sample was positive (Fig.
To determine if the CUFES provides an unbiased sample of all sardine eggs stages, we compared the distributions of developmental stages between the two samplers taken in 91 paired CUFES and CalVET samples during leg 1 of the 1996 survey (Fig.
The CUFES caught only two stage-I eggs; therefore we decided to run a [chi square] test with stage-I and stage-II eggs collapsed into one group.
The foregoing analysis of the 1996 survey data indicated that adequate correlation exists in overall egg abundance between the CUFES and the full-water-column egg samples, but a direct conversion of CUFES data to full-water-column abundance would add considerable variance to an estimate of daily egg production.
We decided to allocate a CalVET at 4-nmi intervals, whenever catch from the CUFES was greater than or equal to 2 eggs/min (1) When the catch from the CUFES began to decrease to fewer than 2 eggs/rain, then CalVETs were stopped (Fig.