Hi, Mark
North Sumba holds less GTs nowdays compared to south sumba. Many big GTs are spear gunned in north (tanjung sasar). Jigging spots are still good in north sumba.
If you like, you can explore Pulau Dana. Located south east of sumba, seems like most south island on Indonesian archipelago.
Many fish there (said some people). Sawu fisherman sometimes catching fish there, but dare not stay in that island. There is a cave that is said to have spirits living in the cave.