[R] Time series (trend over time) for irregular sampling dates and multiple sites

[Abs Spurdle]

> My data has a few problems: (1) I think I will need to fix the effects of
> seasonal variation (Monthly) and (2) of possible spatial correlation
> (probability of finding an item is higher after finding one since they can
> come from the same ship). (3) How do I handle the fact that the
> measurements were not taken at a regular interval?

Can I ask two questions:
(1) Is the data autocorrelated (or "Seasonal") over time?
If not then this problem is a lot simpler.
(2) Can you expand on the following statement?
"possible spatial correlation (probability of finding an item is higher
after finding one since they can come from the same ship"

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