Rusty Crayfish (Orconectes rusticus) is a large freshwater crayfish which is aggressive and habits in the America region. Currently, the fish is rapidly spreading to the North America region with of 350 species reported. Their diverse feeding methods and the elaborate metabolic system have posed a threat to the stability of the ecosystem. If their rate of growth is not controlled aqua organisms including the regular crayfish, fish, and water plants are a danger.
Studies have shown that Rusty Crayfish mate late in the summer or early springs. The male Rusty Crayfish deposits sperms to the female fish, which she stores until her eggs are ready for fertilization in the springs. Once she lays, sperms are released to the eggs, and external fertilization occurs. She then carries the fertilized eggs attached to her lower part of her abdomen until they hatch.
Rusty Crayfish are thought to have originated from the Ohio River Basin, but now they have spread to New England, Michigan Minnesota among other regions. The fish was first seen in the mid-1960s although its capture was in 1973. Henceforth it has been caught in over 20 locations of North America. It is believed that people have played a role in the spread of this dangerous species.
How to identify a Rusty Crayfish
Although an adult Rusty Crayfish can grow up to 4 inches, the average length of an adult crayfish is about 21/2 inches. It is sometimes hard to distinguish between a Rusty Crayfish and other common freshwater lobsters. However, there are a few distinguishing features.
• Grayish-green to smooth reddish-brown claws
• Large front claws with blank bands around the tips
• Reddish colored or dark spots on the sides of their body
• Brown, rusty colored body
Rusty Crayfish Impacts on the environment
The female Rusty Crayfish lays between 70 and 585 eggs which take a maximum of 6 weeks to hatch, and hence this organism multiplies rapidly. Apart from this, it has an elaborate metabolism and an aggressive nature thus displacing other water organisms. If introduced into a new habitat, the Rusty Crayfish can displace the other organisms in the following ways
1. Destroying aquatic plant beds– Rusty Crayfish are known to reduce abundance and diversity of water plants. It has a higher metabolic rate than the regular crayfish and hence destroys aqua plants faster. Therefore, it means that, if the fish inhabits the less productive lakes, all aqua plants will be finished in a short time. Water plants are vital in the ecosystem in the following ways:
• Offer habitats for small animals which provide food for fish and ducks
• Minimize water waves
• Habitat for small fish, e.g., gamefish
2. The Rusty Crayfish are known to eat almost everything in the water, e.g., aquatic worms, snails, fish eggs, aquatic insects, decaying plants and animals, small fish and many more. Therefore, they can reduce the population of fish through eating their eggs and inhibit other organisms through feeding on them and competing with them for food.
3. The Rusty Crayfish reduce the number of the existing crayfish forming a hybrid with some of their species hence producing a highly competitive offspring. Consequently, some species of crayfish drops. Also, Rusty Crayfish, drive the regular crayfish from their daytime hiding place making them prone to predators.
Apart from the problem of ecosystem imbalance, Rusty Crayfish also causes an economic problem in that they reduce fish population as well as making swimming impossible.
Control of Rusty Crayfish spread
People growing Rusty Crayfish for bait have caused its spread. Again, there is no chemical know to kill this crayfish without destroying other water organisms. Therefore, the only control is to use larger fish to feed on them or harvest them for food.