The Las Terrenas Fish Market is open all year. Here you can see what the local fisherman are catching and selling.
Shrimp are brought in from the Samana Bay. Dorado aka Mahi Mahi aka Dolphin Fish is most common along with small clams. There are less frequently other fish there such as Tuna and Marlin, they come from deeper waters typically.
Frankly speaking our interactions with the Las Terrenas fisherman were not enjoyable. They are a rough bunch that demand top price for fish that may or may not be particularly fresh. If you know fish and can get your price take a shot. I sometimes found fish there that was worth buying. My favorite place to go is over the mountain from Las Terrenas to the Samana Bay for their wonderful shrimp.