West Coast Groundfish Observer Program Manual, Part2 - NOAA

CHAPTER 5
3. Break the set into reasonable sampling time periods.
For example, break a 4-hour hauling time into 30-
minute sampling periods.
4. Choose which time periods to sample by selecting a
set of random numbers. For example, there are 8
time periods and the numbers 2, 5, and 8 are drawn
from a hat to select the time periods to sample
during.
5. Tally sample the first skate that begins in each of
the randomly selected time periods. Always start
the sample on a skate knot! Never start sampling in
the middle of a skate regardless of the timing.
6. If the crew is in the middle of hauling a skate when
a sampling time frame occurs, wait until the end of
that skate to start sampling. Sample for the entire
time period. If the vessel is in the middle of a skate
when the time period ends, continue to tally sample
until the entire skate is on board!
Example of Temporal Sampling
1. The skipper on the Miss Fish tells the Observer
that it will take about 3 hours to haul the
longline set.
2. The Observer wants to sample ½ the set.
3. The Observer decides to break the set into 30-
minute blocks of time, which results in a total of
6 sampling periods (180 min / 30 min = 6).
4. Since the Observer wants to sample ½ the set,
he randomly selects 3 of the 6 sampling periods
to sample during. Sampling periods 2, 3 and 6
are selected by randomly drawing cards from a
hat.
5-40 1/30/2004