Land mammals that inhabit wetlands around Galveston Bay include the swamp rabbit, gray squirrel, beaver, muskrat, roof rat, northern rice rat, nutria, raccoon, mink, and river otter. Nutria, a species introduced from South America via Louisiana, has been identified as a particular management problem for some of the bay's wetlands. Nutria can consume large amounts of the emergent vegetation in wetlands, contribute to wetland loss, and can hinder wetland creation efforts in the area.
The most commonly occurring marine mammal in Galveston Bay is the bottlenose dolphin. The navigation channels in Galveston Bay provide a year round deepwater habitat for this popular species. As top predators of the food chain, marine mammals can serve as indicators of overall ecosystem health