One of the most sought-after sport fish throughout Florida, the spotted seatrout (Cynoscion nebulosus) is the second most commonly caught fish in Florida Bay, comprising a significant portion of the coastal Everglades recreational fishing industry worth $880 million annually. Yet, over the last few months, reports from fishing guides and a study by the National Oceanic Atmospheric Administration (NOAA) report significant declines in seatrout populations within the coastal Everglades.
Spotted seatrout spend their entire lifecycle in the bay, although they do move around in response to changing environmental conditions—primarily salinity and water temperature. As a result, seatrout have become important indicators for the health of a variety of recreational sport fisheries throughout Florida Bay. By tracking changes in seatrout populations, we can document the benefits of Everglades restoration and highlight ecological and economic costs of delayed restoration.
The ideal habitat for seatrout spawning in South Florida occurs at temperatures less than 80 degrees Fahrenheit and salinity levels below 37.5 parts per thousand (ocean water is typically 35 parts per thousand). While fluctuations in these values are common in estuaries, this summer’s trend of high heat and extreme drought conditions are further eroding conditions for the species.
As of July 14, 2015, water quality monitoring stations in key seatrout locations are reporting salinity levels of 64.4 parts per thousand, nearly twice as salty as ocean water and well above ideal spawning habitat conditions. “I was just out in Florida Bay, and in Rankin Lake salinities were greater than 65 and there were toadfish kills in the area,” reports NOAA Oceanographer Dr. Christopher Kelble.
Meanwhile, high water temperatures between 90 – 92 degrees Fahrenheit are a result of low rainfall and no freshwater inflow to the bay. This adds additional stress on the survival of juvenile seatrout as well as important prey such as larval shrimp and small fish.
Increased freshwater inflows from Northeast Shark River Slough, as anticipated in the Comprehensive Everglades Restoration Plan (CERP), would help alleviate hypersaline conditions threatening seatrout habitat. Additional relief of greater freshwater flow to Florida Bay could be expanded under the Central Everglades Planning Project (CEPP) currently awaiting Congressional authorization.
Read the full National Oceanic Atmospheric Administration (NOAA) report here.