Witr and Nawaafil

Reciting بسم الله الرحمن الرحيم when continuing to the next surah in Taraweeh Salaah

Q: If someone is leading a congregation, for example Taraweeh. Does the imam need to say بسم الله الرحمن الرحيم after he finishes a surah and decides to continue? For example, if the Imam just finished Surah Baqarah and wants to continue to Al-Imran, does he stop after finishing and continue or does the Imam recite Tasmiyah and then continue to Al-Imran? Please clarify me on this.