Replacing Merfolk Tail with Salamander Bloodline

Merfolk are a powerful race that are balanced out by their poor land movement resulting from possessing a tail instead of legs:

Base Speed (Slow Speed): Merfolk have a base speed of 5 feet. They have a swim speed of 50 feet.

Legless: Merfolk have no legs, and therefore cannot be tripped.

Merfolk have the upper torsos of well-built and attractive humans and lower halves consisting of the tail and fins of a great fish.

The salamander bloodline for the bloodrager class replaces the "legs" with a tail. This tail is different from the merfolk tail in that it is better suited to land:

Serpent’s Tail (Su) At 1st level, your legs twist together into a slithering serpentine tail. Your speed is reduced by 10 feet (to a minimum of 5 feet), and you can’t be tripped.

Your footwear melds into your body and is nonfunctional unless it provides a constant bonus and does not need to be activated. You also gain a tail slap natural attack that deals 1d6 points of damage (1d4 if you are Small) + your Strength modifier. At 4th level, your speed is no longer reduced by 10 feet. At 8th level, your tail slap’s damage increases to 1d8 (1d6 if you are Small) + your Strength modifier. At 12th level, your reach with your tail slap increases by 5 feet.

If my race is merfolk, and I make use of the bloodrager salamander bloodline, can I replace the merfolk locomotion with the salamander locomotion completely?