You Do Need power plug adapter while traveling from Dominica to Canary Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Canary Islands are C, E and F and in Dominica are D and G. This is how they look like.

Dominica

In Dominica, outlets of type D and G are in use.

Type D

Type G

Canary Islands

In Canary Islands, outlets of type C, E and F are in use.

Type C

Type E

Type F