New fish species found deep below ocean surface

This post is based upon the article of the title.
http://news.blogs.cnn.com/2010/10/15/new-fish-species-found-deep-below-ocean-surface/

In summary, scientists have recently found new species of fish and crustaceans deep within the ocean in large chasms, one of which being off the coasts of Peru and Chile. In these trenches, they found new species of fish. One is called the snailfish and is ghostly white in appearance. Other shrimp-like crustaceans were found in abundance, along with cusk-eels. This is a remarkable discovery for the scientific community as a whole because it was previously believed that no fish could survive the conditions within these chasms, which were around 4.5 miles deep. For comparison, the pressure within them is around 10,000 pounds per square inch, which is an awfully high pressure if you ask me.
One thing that intrigued me, though, was this excerpt from the article:

“It begs the question of why and how they can live so deep in this trench but not in any other,” said Niamh Kilgallen, an expert on the creatures at the New Zealand institute.

Well I have a rather simple answer for this 'expert' scientist. These deep underwater trenches are very comparable to the Galapagos Islands. What I mean by that is, as on the Islands, conditions were just right in the trenches for this life to form and evolve over many years. Asking the question "why weren't they in other trenches" is comparable to asking "why weren't the Galapagos Tortoises on other islands in the Pacific.
Another thing that might have contributed to these new types of fish only appearing in select locations is tectonic plate movements. For example, some of the trenches that other species lived in might have become unstable and collapsed due to seismic or volcanic activity. Or, because the trenches were so deep in those locations, too much heat might have seeped from the ocean floor and prevented anything from thriving. If the former hypothesis is correct, we might possible find fossils of fish we never thought existed within ocean trenches or even possibly mere low spots in oceans that have much seismic activity.