A sound like no other
2/13/2019 10:24:27 AM
From MDWFP
While you are on the Mississippi Gulf Coast, whether you are shouting “Fish on!” or throwing some fish on the grill for a delicious dinner, chances are you are enjoying the bounties of the Mississippi Sound. When standing on the beaches of Pascagoula, Biloxi, or Waveland and looking south, you are not looking at the Gulf of Mexico but rather the Mississippi Sound. The Mississippi Sound is the body of saltwater that extends along the coast from Dauphin Island in Alabama to Waveland, and it encompasses 113 square miles. It is bordered to the south by the barrier islands: Cat, Ship, Horn, Petit Bois, and Dauphin. The Mississippi Sound is isolated from the ocean dynamics of the Gulf of Mexico, with water exchange taking place through numerous passes between the islands. The salinity, or saltiness, of the Sound is lower than the Gulf because of the many fresh-water rivers, including the Pearl and Pascagoula, emptying into the Sound and making the water brackish (mixture of nutrient-rich fresh and saltwater). The Mississippi Sound habitat can be classified as an estuary, essentially a place where rivers meet the sea.
Estuaries like the Mississippi Sound have been called marine nurseries, as many species of fishes and invertebrates rely on them at some point in their lives. They play an important role in the life cycles of many marine fish species normally found offshore by providing habitat for their juveniles. The Gulf of Mexico has fewer food sources than estuaries and much less cover from predators. Adult fish typically spawn offshore and the eggs hatch into larvae in a few weeks. These larval fish drift with the currents, but larval fish of estuarine-dependent species move toward shore as they continue to develop. Once they move into an estuary they undergo an extremely rapid transformation into juvenile fish resembling miniature adults. Juvenile fish grow quickly over several months because of the abundance of food and safe habitats in the estuary. At the end of the growing season, they move out of the estuary and join the adult populations offshore, either in the open waters of the Mississippi Sound or the Gulf of Mexico. The Mississippi Sound also has numerous grass beds and oyster reefs which further serve as protective habitat for fish.
The high biological productivity of the Mississippi Sound is an important factor to the substantial seafood industry and recreational fishing industry along the coast. Analysis of commercial fishery landings in the United States shows that estuarine species make up approximately 48 percent by weight and 68 percent by value of the commercial landings. For recreational anglers, estuarine species harvested was as high as 80 percent. Recreational fishing is extremely popular in the Mississippi Sound and can be enjoyed all year round. There are fishing guides all along the coast, many of whom specialize in inshore fishing for some of these estuarine-dependent species, which include the following:
STRIPED MULLET
This fish can often be seen jumping above the water to evade predators. They are one of the most common prey items of other commercially important coastal fish such as spotted seatrout, so they are often used as bait. Anglers most often catch them using cast nets. They eat zooplankton and benthic (bottom-dwelling) organisms and detritus and small invertebrates. If you have ever tried “Biloxi Bacon,” then you have eaten striped mullet, smoked with cane syrup glaze (see related story, page 38).
SPOTTED SEATROUT
Commonly called speckled trout by anglers, these are especially popular in the Mississippi Sound. Starting in April, when the water temperature reaches about 70 degrees, they can be found in the marshes along the coast. The peak season for catching spotted seatrout is in the fall. The spotted seatrout has a long slender body that is silvery grey and has round black spots along the back and upper sides. They have two distinctive large curved canine teeth on the upper jaw. Spotted seatrout need current to keep their eggs adrift until they hatch, so they typically do not spawn inshore. However, the adults will come inshore to feast on all the delicious bait fish the estuaries have to offer. The white flesh has excellent flavor, making the “specks” a coastal favorite.
RED DRUM
Better known as redfish, these fish are probably some of the most famous on the coast. They are the second largest member of the drum family, reaching a maximum length of 5 feet and a weight of about 100 pounds, and are thought to live close to 20 years. They have black spots on the upper sides near the base of the tail. Because they sometimes hunt for food in shallow waters of the estuaries, anglers often sight cast for them, making the thrill of the fight irresistible.
FLOUNDER
These fish are rather unusual in appearance. When they are larvae they look like most other fish. But when they move into the estuaries they undergo a transformation, and the change is quite dramatic. Larval flounder have an eye on each side of the head like other fish, but during metamorphosis, one eye migrates over the top of the head and to the other side so that both eyes are on the same side, all within 12 hours. They then spend the rest of their lives with the side with the eyes facing up and the side without the eyes down on the bottom. They even appear to swim sideways, flexing their bodies up and down, rather than side to side. They are ambush predators, using camouflage to hide on the bottom. When prey get too close, they swim up rapidly to grab the food. They can be caught with a rod and reel or speared while wading in calm shallow waters.
HARDHEAD CATFISH
This catfish has some very interesting reproductive biology. Each female produces between 20-65 marble-sized eggs each season. After the male fertilizes the eggs, he incubates them in his mouth for 40-72 days until they hatch, and then protects them in his mouth for another two to four weeks. The whole time he is doing this he does not eat. So while hardhead catfish do not produce great numbers of eggs, they make up for that by increasing the survival rate for the ones they do lay. They spawn from May through September in shallow estuarine waters.
SHRIMP
The shrimp fisheries in the Gulf of Mexico are some of the most valuable fisheries in the United States. There are several species of shrimp, but three are of economic significance in the Mississippi Sound: the brown, white, and pink shrimp. Brown shrimp, which get their name from their sandy-brown color, can change color to match their environment. They can be distinguished from the other Mississippi gulf shrimp by grooves on the back of their shells. The largest of Mississippi gulf shrimp species is the pink shrimp, which can grow up to 11 inches and live for up to two years. White shrimp get to a large size and have long antennas and smooth shells that help distinguish them from the brown shrimp. Shrimp are important in estuarine and offshore food webs. They are a food source for many predators, such as sea red drum, black drum, sea catfish, flounder and spotted seatrout.
The Mississippi Sound is a priceless resource for Mississippi, providing recreational fun through fishing and boating, economic value from the large seafood industry, and a vital and growing tourism industry, as well as cultural value. With a large portion of Mississippi’s watersheds draining into the Mississippi Sound through the Pascagoula and Pearl rivers, those of us living up river impact what ends up in the Mississippi Sound. We can all make a difference in the health of this important Mississippi estuary.
Visiting the Mississippi Sound gives you a view of the habitat from above the water. The aquariums at Mississippi Department Wild-life, Fisheries, and Parks’ (MDWFP) Mississippi Museum of Natural Science (MMNS) give you a unique underwater window into the world of the Mississippi Sound. Three aquaria at the museum depict saltwater habitats found along the gulf coast, the largest of which is home to many of the fish species common to the Mississippi Sound estuary.
Starting Jan. 26, visitors to MMNS can view the Ocean Bound exhibit, which simulates a journey through similar watersheds and shows how actions on land can affect the ocean. Through the exhibit’s combination of aquatic species and ecosystems, video, and hands-on activities, visitors can explore watersheds, environmental impacts, and the ocean’s vast diversity.
Karen Dierolf is an aquarium biologist for MDWFP’s Mississippi Museum of Natural Science.
