Dear All,

I am trying to model the habitat mapping of 4 sharks species and my data are zero inflated and positively skewed. I did some tests fitting GAMs with negative binomial family (with theta between 1-10). The zero percentages are between 56-77%. Is this the best way to go? Some people have used VGAM (with zero inflated negative binomial) but my concern is that using the VGAM model I would lose the basic ecological assumption (e.g. if the habitat is not suitable your species is not there = 0 abundance).

Thank you very much in advance for any suggestions!

Kind Regards,
Valentina



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