Aurelie,

with this information, I'm afraid that your data cannot be considered 
as marked point partterns because your  "points" are not the result 
of a stochastic point process but instead are selected (although 
hazaphartdly) for sampling pourposes. Others may correct me but I 
would find inappropriate using point pattern tools to analyze your data.

If you are at looking at habitat selection and  geographic 
distribution of abundance of skate species you may consider 
instead  other approaches such as species distribution modelling. 
Package dismo could be a good start.

Cheers,

Marcelino


At 17:05 18/10/2011, GodinA wrote:
>Marcelino,
>
>My dataset is coming from annual bottom-trawl surveys in waters off
>Newfoundland and Labrador Region, Canada. I am looking at habitat selection
>(relationship to depth & temperature), geographic distribution, and
>abundance of skate species in the region in 2009.
>The survey use a stratified random design, with the allocation of units
>proportional to stratum area within a Division (region), and a minimum of 2
>units in all strata. Each unit being a standardized tow i.e., 30-minutes tow
>at 3.5 knots. The map shows all strata.
>For each unit, I have information on species caught, number & weight, depth,
>temperature, latitude, longitude, strata No., and Division No., time of the
>day, among others.
>
>Let me know if you need additional details,
>Thank you very much,
>
>~Aurelie
>
>
>
>
>
>-----
>Aurelie Cosandey-Godin
>Ph.D. Student, Department of Biology, Dalhousie University
>Industrial Graduate Fellow, WWF-Canada
>Email: godina@dal.ca | Web: wormlab.biology.dal.ca
>
>--
>View this message in context: 
>http://r-sig-geo.2731867.n2.nabble.com/Extracting-GIS-file-best-approach-tp6904616p6904976.html
>Sent from the R-sig-geo mailing list archive at Nabble.com.
>
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____________________________________

Marcelino de la Cruz Rot
Depto. Biologia Vegetal
EUIT Agricola
Universidad Politecnica de Madrid

tel: 34 + 913365435
____________________________________  
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