To further minimize the random sampling error in these surveys, sampling effort could be increased, or modeled predictions of potential sardine habitat could be used to optimally plan both DEPM
and acoustic--trawl surveys, and thus save valuable time to increase sampling effort in areas of expected sardine presence.
To generalize the DEPM model run to the NHEXAS-Maryland foods, we matched the 131 foods in the NHEXAS-Maryland dietary checklist to foods in the NFCS database (22).
Metal concentrations measured in food items as part of the TDS were chosen as the source of residue data for the DEPM runs.
Acoustic estimates of sardine abundance compare well with those of the 2010 assessment but were higher than those of the DEPM (Fig.
Unlike the DEPM, acoustic-trawl surveys do not depend on the timing of spawning.
6), or because during the 2005 California survey, few trawls were taken north of 34[degrees]N latitude where most migrants had resided according to the 2004 DEPM survey off California, or it could have been due to a combination of both factors (Fig.
According to the April 2004 DEPM sardine survey off California, the large mature females, in particular those [greater than or equal to] 200 mm SL, were spawning very vigorously (S=0.
How ever, because the process of POF degeneration is continuous and DEPM samples are usually obtained opportunistically throughout the day, the direct assignment of POF stages to daily classes of spawning fish can be imprecise.
Because of the above unresolved issues of the POF method (that can be species specific), the spawning fraction remains the most poorly estimated DEPM parameter (Hunter and Lo, 1997; Stratoudakis et al.
Although the DEPM is able to provide relatively robust estimates of [B.
However, because of the small size of the fishery and the difficulty in securing additional research funds, no fishery-independent method of estimating biomass other than the DEPM was undertaken.
Using these findings as a guide, in 1997 we carried out an adaptive allocation DEPM
survey in which the numbers of sardine eggs collected with the CUFES were used to determine subsequent locations of vertical net tows.