The body was initially a freshwater lake and was stocked with tilapia, gulf croaker, orangemouth corvina, and sargo, which sustained an important sport fishery and provided food for birds. By the 1960s, its rising salinity had begun to jeopardize some of these species. A September 2019 report stated that 20 years earlier, "there were some 100 million fish in the Sea. Now, more than 97% of those fish are gone". It is now too saline for most species of fish. Massive fish kills involve the oxygen-depleting combination of summer sun and salt. The fish suffocate as salt water carries less oxygen than fresh water. The dead fish wash up in mass quantities on the beaches.