West Coast Groundfish Observer Program Manual, Part2 - NOAA

CHAPTER 5
Example of Systematic Sampling
1. The Miss Fish sets a line with 10 skates.
2. The Observer on the Miss Fish randomly
selects skate 2 to sample by selecting a
number from a random number table.
3. The Observer estimates that 100 sablefish will
be caught in skate 2.
4. The Observer wants to collect 20 sablefish to
use for an average weight determination.
5. The Observer determines the frequency to
collect sablefish by dividing 100 by 20 to get a
collection frequency of 5.
6. Starting at the beginning of skate 2, the
Observer collects every 5 th sablefish until a
total of 20 sablefish have been collected.
7. The Observer weighs the 20 sablefish and
uses the subsample weight to calculate the
average sablefish weight.
Average Weight Calculations
On Fixed Gear vessels, all species in the tally sample
MUST have an actual count. However, not all individuals
need to be weighed. For some species, an average weight
calculation can be applied.
Total Sample Wt. = Wt. of subsample X Total # in Tally Sample
# In subsample
5-44 1/30/2004