Tiger prawns are large-bodied prawns that are native to the Indo-West Pacific Ocean but have established invasive populations in other areas, including in the Gulf of Mexico. Tiger prawns get their common name from the stripes that cover their shell. This species is a highly valuable seafood species, is targeted widely by commercial fishers throughout its range, and is grown in aquaculture farms all over the world. Along with true crabs, lobsters, and other prawns, the tiger prawn is a decapod; it has ten legs, and it is covered with a spiny exoskeleton that provides it some protection from potential predators.
Tiger prawns progress through several life history stages in a short amount of time and mature quickly. Adults live on soft bottoms. Unlike many aquatic invertebrates, tiger prawns reproduce via internal fertilization. After mating, females release hundreds of thousands of fertilized eggs, which quickly hatch. Planktonic larvae live in the open ocean, and juveniles live in estuaries, before moving to the preferred adult habitat near the age of maturation. Like in all decapods, the tiger prawn's shell really is a skeleton on the outside of its body. The exoskeleton does not expand, and therefore the prawn must molt (or shed) it regularly in order to grow bigger. Before molting, an individual begins building a new, larger skeleton inside the existing one. As it gets too big to be contained, it splits open the outer shell, and the new exoskeleton hardens. During this process, the new exoskeleton can be soft for several hours, and the prawn is highly vulnerable to predation.
Adult tiger prawns are omnivorous and eat a wide variety of food, including algal and plant material, other invertebrates, and dead/decaying organic matter. Most soft-bottom fishes and several invertebrates eat juvenile and adult tiger prawns. This species is also the target of a large fishery throughout most of its range. Of concern to conservationists and resource managers is the primary gear with which this species is captured. Tiger prawns (like other prawns around the world) are captured by bottom trawl. This method is known to cause significant damage to seafloor habitat and known to capture an incredible amount of non-target species. Numerous species of sea turtles, sharks, rays, bony fishes, and other invertebrates are accidentally captured in prawn trawls. Without continuing advances in the gear used to capture tiger prawns and other prawns, ecosystems in their geographic range will continue to directly or indirectly suffer. The use of prawn traps is an alternative gear type that is much more environmentally friendly. Traps do significantly less damage to the seafloor and are not associated with the high levels of incidental bycatch experienced with bottom trawls. Unfortunately, traps are much less lucrative for fishers and may not be a realistic alternative for those who make a living selling tiger prawns.
Another concern associated with the tiger prawn is the wide-scale aquaculture for this species. Though aquaculture may lower the fishing pressure on wild populations of some species, tiger prawn farming is highly destructive to coastal environments. Prawn farming, in general, is a major threat to mangrove forests, which are destroyed when building farms. Accidental release of tiger prawns from farms outside of their native range has resulted in documented invasive populations in some places around the world. Finally, overfishing of juvenile tiger prawns to be raised in ponds and forage fishes to feed the prawns and excessive pollution when farms are “flushed” using seawater are two more problems associated with tiger prawn farming. Without increased regulation of this activity, coastal ecosystems near prawn farms will continue to be threatened by irresponsible farming policies.
Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.