Cooper and Mangel: Metapopulatlon structure in the conservation of salmonids 



219 



the state of being sink habitats, which would then 

 have resulted in only a few instances of sustained or 

 increasing metapopulations (as described above). 

 Because the number of migrants from one deme to 



another decreases with distance, the year in which 

 the maximum deme size is attained by the sink de- 

 creases as the distance from a source increases; thus 

 the sinks rely on source populations for their viabil- 



