FISHES OF THE GULF OF MEXICO
FISHES OF THE GULF OF MEXICO. There are probably more than 600 species of Texas marine fishes, counting all habitats from the estuaries to the ocean depths of the abyssal zone 150 miles off the barrier islands. This is more than all the different kinds of Texas freshwater fishes, reptiles, amphibians, and mammals put together. At least 120 families of marine fishes live along the Texas coast. Getting an exact count is difficult because there are few effective barriers in the ocean, and it is large and difficult to explore; secretive species therefore often go unnoticed.
Most abundant in numbers are the schooling fishes, including the herrings or shads (Clupeidae); the commercial Gulf menhaden (Brevoortia patronus); the anchovies (Engraulidae), of which the most common is the bay anchovy (Anchoa mitchilli) which abounds in brackish water and spawns anytime water temperatures exceed 20° C; and the striped mullet (Mugil cephalus), most notable in its lazy jumping, but swift when chased by predators such as trout, jacks, or another of the many species that depend on it for food. The most diverse family is the sea bass (Serranidae), with nearly forty species, but the gobies (Gobiidae), jacks (Carangidae), drums or croakers (Sciaenidae), and flounders (Bothidae) all have around twenty each. More species have ranges that extend farther north than south, allowing the coastal fishes to be characterized as warm temperate, but many are tropical, especially offshore.
Many species are found closer inshore when young and move offshore as they grow. This movement is frequently associated with seasonal changes, and large movements are especially stimulated by northers. Recent extensive collections have verified and extended observations of the zoning of certain species. For example, in the bays and northern Gulf near-to-shore, croakers are the common bottom fishes. These are replaced on the continental shelf by sea robins (Triglidae), on the middle shelf by small sea basses, and with snappers (Lutjanidae) and porgies (Sparidae), especially the longspine porgy (Stenotomus caprinus), on the outer edge.
The state of Texas has had practice in freshwater stocking and is pioneering the stocking of selected marine species. The first to be stocked was red drum (Sciaenops ocellata). Stocking was not possible in salt water until recent breakthroughs in spawning red drum and other species allowed the raising of large numbers of fingerlings. Stocking is based on the premise that reproduction is the controlling factor in numbers of fish and has been used in fresh water where reproduction was inadequate or absent. Stocking effects in salt water are yet unknown, and stocking does not seem to alleviate the problem, since scarcity of saltwater species is often a consequence of port development, which removes the critical shallow habitat needed by the young to grow toward maturity.
Popular sport fishes include the sea trouts (Cynoscion), red drum, and southern flounder (Paralichthys lethostigma) inshore, and the billfishes, including sailfish (Istiophorus) and marlins (Makaira, Tetrapturus), mackerel (Scomberomorus), and red snapper (Lutjanus campechanus) offshore. Inshore commercial fishing has been legally restricted and includes mostly black drum (Pogonias cromis), southern flounder (Paralichthys lethostigma), and menhaden. The latter is a very large fishery limited to the upper coast.
Two especially interesting habitats are the offshore reefs formed on top of protruding salt domes and the Laguna Madre, where salinities frequently exceed that of seawater. The offshore reefs, although poor versions of tropical coral reefs, contain an impressive assembly of fishes. Some of these, such as the beautiful spotfin butterfly fish (Chaetodon ocellatus), drift inshore as larvae to spend their first summer on the similar habitat of the inlet jetties.
Though there are areas on the upper Texas coast where freshwater fishes actually intrude into the bays, the shallow Laguna Madre, on the driest part of the coast, has historically exhibited salinities double or even triple that of normal seawater strength during dry years, causing many fish to die. The completion of the Gulf Intracoastal Waterway to Port Isabel in 1949 provided sufficient circulation to prevent recurrences, but the shallow lagoon still suffers very large mortalities from killing freezes such as the Christmas freeze of 1983. The freezes are worse here because the lagoon is shallow, the distances to deeper and warmer water are great, and the cold fronts strike with great rapidity (see BLUE NORTHER).
Coastal fishes have provided much sport and essential food from the time of early settlement to the present. As early as 1685 people were known to eat fish killed by freezes. Fishing and fish watching with snorkel or scuba are large industries on the coast. Threats to fish populations include development, pollution, and lack of sufficient freshwater in the bays.
A. C. Becker, Fishing the Texas Coast: Inshore and Offshore (Houston: Cordovan Corporation, 1975). Gordon Gunter, Studies on Marine Fishes of Texas (Austin: University of Texas Institute of Marine Science, 1945). H. Dickson Hoese and Richard H. Moore, Fishes of the Gulf of Mexico: Texas, Louisiana, and Adjacent Waters (College Station: Texas A&M University Press, 1977).