Cannibalism in Aquaculture - Research Paper Example

 Cannibalism in aquaculture is an issue of concern among marine biologists and many scientists in related fields. This is because, in any given aqua culture, cannibalism has the potential to eliminate over 50% of the initial population. There are a number of reasons that trigger cannibalism in aquaculture. These reasons include the assortment of species within the aquaculture, the population density and survival instincts. Studies also reveal other reasons such as the psychology of the aqua population. However, there are man made and natural factors that act as catalysts and, therefore, aggravate the occurrence of cannibalism. Man made factors include the ability and knowledge of an individual to maintain an aqua culture. One the other hand, natural factors are such as the aggressive nature of some aqua species (Gregory, 2007). The assortment of species within an aquaculture plays a vital role in determining the prevalence of cannibalism. Most aquatic animals are omnivorous with predominant herbivorous tendencies. However, there are some types of species are cannibals by nature. Cannibalism is more dominant in predatory species than in others. Most crabs, Cray fish and the Malaysian fresh water shrimp fall under these categories. As such, even when the aqua culture consists of a similar, well fed, species, cannibalism is likely to occur. The crabs will feed on each other for a number of reasons. One is for sustenance while others feed in order to prove dominance over a territory (Baras, 2002). Cannibalism also increases with the density of the population. Studies show that, in a largely populated environment, the aqua population tends to acquire an aggressive nature. One such study carried out n blue crabs revealed that there were more deaths as a result of cannibalism in densely populated environments. The psychological state of any population may have an impact on its social interactions. Psychological states rely on factors such as the natural habitat of a species. Animal psychology studies indicate that the artificial living environment of any animal should resemble the natural environment. For instance, the rainbow trout is more likely to develop a cannibalistic nature hen exposed to an automatic feeding system than in a self feeding system. Population density also leads to stress among the aqua population. Stress causes the development of aggressive behaviors and one of these behaviors is cannibalism (Huntingford, 2002). Still on population, the stages of development of an aqua population are particularly crucial in determining the existence of cannibalism. In the wild, the larger stronger animals dominate over the smaller weaker ones. It is no different in the aqua population. The larger marine animals prey on the smaller ones. Predation may occur at any of the stages of development even as early as the larvae stage. In crustaceans, cannibalism is dominant during molting because the newly molted crustaceans have no defense mechanism. In the absence of the smaller animals or in the event that the smaller animals are too quick, the weak and sickly ones fall prey (Clay, 2004). The ratio between predators and the prey also increases the chances of cannibalism in aquaculture. Cannibalism increases, when the number of predators exceeds that of the prey. On the other hand, the more prey there is the lesser the rates of cannibalism. Survival instincts, therefore, determine the behavior of the marine population. However, in an artificial environment, the owner should ensure to feed the creatures. Research on the feeding cycles in relation to the amount of food has yielded two results. First, if the feeding is not regular there is a possibility that cannibalism will crop up. The second is that the amount of food given has to be sufficient to feed the larger and the smaller fish, or they will result to cannibalism. Dietary preferences may also cause the occurrence of cannibalism. Crayfish require large amounts of proteins to develop. In some situations, especially when the fish remains confined to an aquarium, these dietary needs may not receive due attention. In seeking alternatives, the strain may result to feeding on its own (Baras, 2002). For an individual intending to rear marine animals at home for leisure or commercial gain, the need to curb cannibalism is crucial. There are several methods one can utilize in order to mitigate cannibalism. One of the methods is the focus on rearing strains that have low or no tendencies of cannibalism. For instance, most house holds prefer to rear gold fish. Unless, under extreme circumstances such as prolonged hunger, goldfish remain herbivorous. However, there are claims that domestication can increase aggression even in the politest of fish (Huntingford, 2002). Crabs and crayfish may prove difficult to maintain. As such, experts suggest that distinct conditions suffice in order to avoid the occurrence of cannibalism. One such condition is to keep a small population of a strain in a large space. A smaller population reduces the number of targets for the cannibal. Secondly, the strain should be fed on a regular basis with recommended food and enough rations. This ensures that the crabs are never hungry and, therefore, feel no need to feed on each other. Other species, such as the arctic char, may have cannibalistic tendencies but are not in actual sense cannibals. People should also take care to feed the species in regard to their dominant diet. If a fish requires protein packed food, then it is imperative that they receive packed food (Gregory, 2007). Another way of preventing cannibalism is separating the larger population from the smaller population. This method, sized heterogeneity, is efficient especially in the rearing of sharp-toothed catfish. Also, in the event that there are immature larvae strains, it is imperative to separate them from the mature ones. Also, separating two species that have size discrepancy is a mitigating factor. One research study shows that, in the event, that there exists a variety of species in one aqua culture, aggression increases. As mentioned earlier, aggression is a potent breeding ground for cannibalism Findings also show that cannibalistic tendencies can be identified at an early developmental stage especially in species such as perch (Southgate, 2012). In regard to the environment the aqua population lives, there are a number of modifications a marine farmer can embrace to help them reduce cannibalism. An excellent example is reducing the temperature of the aquarium, to bellow 20 degrees Celsius. Lowering the temperature improves feeding conversion and reduces cannibalism. This is because high temperatures increase the feeding requirements leading to the onset of hunger shortly after feeding. Secondly, increasing the turbulence coupled with low light intensity in the habitat make it difficult for the cannibal strain to catch up with its target (Stickney, 2009). In conclusion, cannibalism results from a combination of many factors. Biological factors include the growth stage, genetics and size disparity. Environmental factors encompass stocking density, restrictions on feeding temperature and light intensity. There is no isolation of causes because, at a given moment, all these factors are in play. Cannibalism is common in the larval stage but in extreme situations can occur in adults. References: Baras, E. (2002). Effect of stocking density on the dynamics of cannibalism in sibling larvae. Belgium: University of Lie`ge Press. Clay, T. A. (2004). GROWTH, SURVIVAL, AND CANNIBALISM RATES OF ALLIGATOR GAR. Maryland: University of Maryland Press. Gregory, N. G. (2007). Animal Welfare and Meat Production. London: CABI. Huntingford, F. (2002). Aquaculture and Behavior. New York: John Wiley & Sons. Southgate, J. S. (2012). Aquaculture: Farming Aquatic Animals and Plants. New York: John Wiley & Sons. Stickney, R. R. (2009). Aquaculture: An Introductory Text. London: CABI. Read More