Shrimp

 

Shrimp have a very busy, but short life. In 1½ years, shrimp molt and grow through 7 stages. A shrimp’s life begins in warm, salty Gulf water as one of almost 500,000 small eggs attached to the legs of a female shrimp. A few days later, nauplius larvae hatch from the tiny eggs and float with the swift currents in the Gulf. These small shrimp look like tiny spiders and have no swimming legs. At this stage, the shrimp do not eat other organisms but live on its nutrition for two weeks. The next stage is called protozoea. These fuzzy-looking shrimp quickly grow into the fourth stage of a shrimp’s life cycle, mysis. Unlike earlier stages, these shrimp can respond to sunlight by moving deeper into the Gulf water to hide from predators. The fifth stage of growth is postlarvae. For the first time, shrimp can cling to the bottom of the estuary floor. For 4 to 6 weeks, these medium sized shrimp grow into juvenile shrimp. Juvenile shrimp like to hide and eat under plants in shallow, salty water. These shrimp grow into the sixth stage known as subadult. Subadult shrimp only swim to the top of the water at night. They migrate with the currents and grow into adult shrimp with the changes in temperature. When the water temperature rises, the shrimp return to the Gulf. Adult shrimp live in 60 to 500 ft of water, a depth about the length of 1½ football fields. Throughout their life, a shrimp eats many different things such as micro-algae, worms, decaying animal parts, plant roots, coral, and other shrimp. Their eating habits contribute to the health of Louisiana’s estuary.

 

Species of shrimp

Many species of shrimp live in the Gulf of Mexico and Louisiana’s estuaries. Two of the most popular to eat are brown shrimp and white shrimp. White shrimp are easy to notice. They have long, black antennas and a smooth tail shell. A white shrimp can be a few different colors. White shrimp are pink if caught during the night. White shrimp may be white or grey, depending on the temperature and the amount of salt in the water. Migrating shrimp have red legs. A shrimp’s color does not affect its taste once cooked.
White shrimp begin their life cycle in the Gulf. When the temperature of the Gulf is just right, a female white shrimp spawns only two or three times. They migrate toward land in the early summer. They feed and grow until the early fall. When the water temperature becomes cooler, white shrimp migrate back into the Gulf during August, September, and October. Once they begin migrating, white shrimp in coastal and bay waters are harvested. White shrimp grow the largest size so shimpers love to harvest them.
Brown shrimp are similar to white shrimp in many ways. Like white shrimp, their colors can vary. Small brown shrimp in estuaries are dark grey. Near shore in Gulf waters, brown shrimp are tan. Large brown shrimp in offshore waters are dark brown or red. Unlike white shrimp, the color of a brown shrimp does affect its taste. Because natural iodine causes the brown color in shrimp, dark brown shrimp have a bitter, iodine taste. Brown shrimp’s anatomy is different than white shrimp. They have brown, medium length antennas and small grooves on their shell. Brown shrimp also have a toothed rostrum, a sharp piece of shell that points out over their eyes.
Brown shrimp also begin their life cycle in the Gulf. By responding to a change in water temperature, they spawn all year long in the deep waters of the Gulf of Mexico. They migrate inland to the estuaries before the white shrimp in the winter. Brown shrimp feed and grow until early summer. They are harvested during the summer in May, June, and July while still inland and rather small. Brown shrimp migrate back to the Gulf of Mexico in the late summer to spawn.
Shrimp is one of Louisiana’s most valuable resources. Louisiana has more shrimp landings than any other state. Louisiana shrimpers work so hard that they are the #1 producer of shrimp in the U.S. In spite of this, Louisiana shrimp accounts for only 10% of the shrimp eaten in the United States! How could this be? Most people buy shrimp that is imported from other countries. Shrimpers in Louisiana are forced to lower the price of their shrimp to compete with the price of the imported shrimp. This low price really hurts Louisiana’s shrimp industry. By reducing their prices, Louisiana shrimpers may not meet their business’ financial needs. You can help support Louisiana’s shrimp industry in different ways. One way is to only buy Louisiana shrimp. You can always visit local docks and buy shrimp directly from shrimpers. Local shrimp is much fresher than the frozen, imported shrimp. You can even ask for Louisiana shrimp at restaurants and grocery stores.

When buying shrimp

When buying shrimp, you should consider a few important details. Some shrimp packages are labeled “head on.” This means the shrimp’s head was not removed. Other packages are labeled “headless.” This means that the shrimp’s head was removed. Sometimes shrimp are labeled as “green headless” shrimp. “Green” simply means that the shrimp are organic and unprocessed. Both brown and white shrimp occasionally have black spots on their shells. These black spots are caused by the reaction of natural amino acids and sunlight. Although they do not look appealing, these shrimp do not taste different and are safe to eat. Shrimp are labeled by how many shrimp there are per pound. On the package of shrimp are two numbers. For example, a package may be labeled 61/70.” This means there are about 61 to 70 shrimp per pound in the package. A smaller number indicates bigger shrimp. For example, one package might have been labeled as 16/20. These shrimp are much larger than the 61/70 shrimp and contain 16 to 20 shrimp per pound. Sometimes you might see a package labeled as U/10. This package contains about 10 “colossal” shrimp per pound.
Fishermen recently found a new invasive species. While fishing in the Gulf of Mexico, they caught a few Tiger shrimp. Tiger shrimp are the largest shrimp in the world. They are natives of Southeast Asia, Philippines, and Australia. Adult Tiger shrimp are 36 cm long. That is about 21 cm larger than adult white shrimp! Adult Tiger shrimp usually have black and white stripes on their tails. Their bodies may be brown, green, red, grey, blue, black, or yellow. Their color depends on the temperature and the amount of salt in the water. Just like white shrimp, their color does not affect their taste.
Tiger shrimp begin their life during the night. A female shrimp will spawn about 750,000 eggs that are attached to her legs. These eggs hatch in 15 hours. They quickly grow through the same 7 stages as white and brown shrimp. Tiger shrimp grow into the adult stage in just a few months. Just like other shrimp, Tiger shrimp live on the bottom of estuaries during the day. They swim around in search of food during the night. Tiger shrimp are predators. They eat other shrimp and small fish. Because Tiger shrimp are new to the Gulf of Mexico, scientists are not sure if they will become invasive. Scientists must track this species of shrimp in local habitats to determine if the Tiger shrimp will harm the environment. If you find a Tiger shrimp, you should call BTNEP at (985) 447-0868 or Louisiana Wildlife and Fisheries at (225) 765-2800.

Shrimp are important to Louisiana’s estuary. Their niche, or role, changes with each new stage of their life cycle. A shrimp’s niche can be determined by studying the physical changes at each stage in its life cycle. Below is the life cycle of a shrimp. Label each stage. Then in the first block, describe the physical characteristics of the shrimp at each stage. In the second block, hypothesize how the shrimp’s physical traits help it adapt to its changing environment. To check your answers, go to http://www.seagrantfish.lsu.edu/biological/shrimpniche.htm#lifecycle.
Americans eat 1 billion pounds of shrimp in one year!

Americans eat more shrimp than any other food.