Introduction
The vaquita is a small naval creature found in the Gulf of California and is in danger of extinction. Very few people have gotten the opportunity to see this species and many people may not be able to see it now that its existence is threatened. The vaquita looks like a curved stocky porpoise, and it is the smallest of all the porpoises in the world.
It survives in shallow waters. It is even believed to survive in lagoons where the water can hardly cover its back. Most Vaquitas are found on the northern part of the Gulf of California within Colorado River delta. This paper will give more information about the vaquita, explain some of the reasons that are causing its decline, and highlight some of the steps taken by the Mexican government to conserve this rare species.
A newborn Vaquita weighs about seventeen pounds and is approximately 30 inches long. Adults are 150 centimeters which is equivalent to 4.92 feet, and weigh not more than 50 kilograms, making then the smallest cetaceans in existence. Most parts of its body are grey in color and it has a smaller skull compared to other porpoises. Calves are usually a dark shade of grey and as they grow older, they are actually tri-colored having a whitish belly, light grey sides and remaining dark grey on their back.
Although they are commonly compared and closely related to dolphins, they vary in many ways. They have spade shaped teeth, rounded beaks and are stouter than dolphins who also have no beaks. Their triangular shaped fins are surprisingly larger and higher than most porpoise species. From far away, Vaquitas look like bottlenose dolphins but their behavior clearly distinguishes them from other cetaceans.
Social and Reproductive Life
The Vaquita are more agile and less social than dolphins. They appear to be comfortable porpoises that like swimming and are sometimes found relaxing leisurely along the shoreline, but normally they barely come into contact with the sea surface and disappear for long periods, remaining inconspicuous.
They are also afraid of boats of all kinds. If a boat appears near them, they either hide under water or move to a different position. Vaquitas rise to the surface of the water to take in fresh air and then go under water for a long period of time. They like feeding on fish species, especially the smaller ones although they are known to be nonselective feeders and can feed on almost anything that crosses its path.
Being that they limit their living area, they tend to eat squid, grunts, benthic fishes and crustaceans. They have a loud shout indistinct blow. They have their own high frequency click they use to communicate with other vaquitas while plotting their course through waters. Vaquitas give birth to calves during spring, and gestation normally takes about ten to eleven months. Three to six years is believed to be the Vaquitas maturity age. Vaquitas are believed to have a life span of about 21 years (Jefferson, et al 2008).
Reasons for its Decline
It is hard to find a person hunting Vaquitas because many people do not know much about them. Actually their existence was realized in 1958, after a survey was carried out by dedicated scientists. Since then, other scholars have developed an interest on this rare species and are carrying out research to understand more about them and how their survival can be enhanced.
Their existence is being threatened since they are normally trapped in gillnets that are used for fishing the totoaba which is also found in the Gulf of California. It is important to note that this species reproduces very slowly because they are very few in number. Therefore, if one female Vaquita is trapped in gillnets, it poses a very great threat to their survival (Leatherwood, et al. 1988).
The population of the Vaquitas has declined at a very high rate (15% every year). Their existence is mainly threatened by commercial fishing, which takes place within Colorado River delta. However, other species are being fished and this threatens the survival of the Vaquita. It is estimated that the population of the vaquita may be declining at a rate of about eighty percent for the next 20 to 30 years, which may render the species extinct.
Commercial fishing still stands as the greatest threat to the survival of the vaquitas, although there are other threats such as habitat degradation, pollution, and inbreeding, given that they population is very low. A lot of non-environmental friendly waste is being damped in Colorado River which is a threat to the security of the vaquita.
Many vaquitas have died from suffocation (given that they stay underwater for a longer period than they stay on the surface) and they are still facing the threat of environmental pollution. Agricultural farming has also increased around the area with many farmers using water from Colorado River for irrigation (Reeves, et al. 2002).
This has resulted in a decrease in the volume of water in the river thereby interfering with the habitat of the vaquitas. Apart from the use of water, the use of fertilizers and pesticides is on the increase and most of these chemicals find their way into the river. This does not only cause death to the Vaquitas, but to all other aquatic animals.
Inbreeding is also a major reason for the decline of the vaquitas. As seen earlier, a single calf takes about six years to mature and be able to reproduce. Also a female vaquita can only give birth to a single calf and this takes place annually especially during spring. Let’s assume there are about 100 female vaquitas out of the total population, this means that fewer than 100 calves will be born each year because the gestation takes almost one year and not all this vaquitas may be able to survive throughout the year.
If 70 calves are born each year, after six years we will have about 420 new vaquitas (holding all other factors constant). However, it is estimated that, the rate of death can go up to 84 individuals meaning that, all the calves may die before they are able to reproduce. The number of females may also decline.
Reduction of the flow of Colorado River
- Other risk factors for the decline of the vaquita species include but not limited to;
- Increased rate of incidental mortality in fisheries
- Indirect effects of fishing whereby the vaquitas are trapped in fishing nets
- Use of hydrocarbon pesticides and fertilizers for agricultural purposes mostly in the Mexican basin
- Reduced flow of the Colorado River which interferes with the vaquitas habitat
- Reduction of the flow of Colorado river has not yet had negative effects on the current productivity but poses great threat on the survival of the vaquitas 9 (Lavín & Sánchez 1999)
If the flow of the river continues to decrease, the inbreeding of the vaquitas will be affected which in turn will affect the population growth. Northern Gulf ecosystem has been affected by the reduced flow of the Colorado River and has been experiencing large-scale stresses also caused by intensive shrimp trawling.
There is no cause to suppose that these stresses have enhanced habitat environment for the vaquita. On the other hand, it must also be recognized that there is no proof to propose that food shortages are distressing the reproductive victory or escalating the mortality of vaquitas. Bycaught and trapped specimens observed recently have shown no signs of emaciation, and mothers with healthy calves are frequently experimented during studies, signifying that reproduction is taking place in the population
Reduced flow of the Colorado River seems not to be an immediate threat, that is, it is not affecting the present population of the vaquita. This finding is based on three factors:
- Nutrient levels and rates of prime productivity apparently are high in the northern Gulf of California.
- Vaquitas have a somewhat varied diet and do not appear to rely entirely on one or a few prey species.
- Out of all the vaquita species that have been examined this far, none of them has shown signs of malnourishment or poor nutritional status.
However, in the long term, changes in the vaquita’s environment due to the reduced flow of the Colorado River may lead to a decline in the levels of nutrient concentration. This is a matter of concern and ought to be investigated if the survival of the vaquitas is to be guaranteed.
Other less well-characterized and longer-term risk factors include the possibility of interruption by trawling to influence vaquita behavior, and the tentative effects of dam construction on the Colorado River and the ensuing loss of freshwater input to the upper Gulf. Environmental change from reduced freshwater flow of the
Colorado River was cited as a ‘major cause’ of the declines. Thus, by the mid-1990s, two distinct and contradictory views concerning the root causes of the vaquita’s current shortage had been expressed, one is by-catch in large-mesh gill nets and the other is damming and abstraction of water from the Colorado River drainage system in the United States was the chief culprit (Lavín & Sánchez 1999).
Conservation Efforts
Traditionally, the position of the institute and of the Federal Government had been that no evidence was present to verify that the vaquita was endangered. Furthermore, the institute’s position had been that even if the species was in danger, the main cause was the lack of freshwater input to the Gulf as a result of the damming of the Colorado River.
Today, the number of Vaquitas estimated to be alive varies from one hundred to three hundred. In 2000, research was conducted by the Vaquita recovery committee which discovered that about 40 to 80 Vaquitas die every year in the hands of commercial fishermen (Shirihai & Jarrett 2006). A reserve was created on the northern side of the Gulf of California by the government of Mexico to prevent the extermination of the vaquitas.
Trawlers were banned from fishing in the reserved area and with this ban the number of Vaquita killed each year has reduced. However, most conservationists are still concerned about the survival of the vaquita especially now that the use of pesticides along the shoreline has increased and the flow of water from Colorado River has reduced mostly due to increased irrigation around the area.
The International Union for Conservation of Nature and Natural Resources (IUCN), believe that the Vaquita is the most endangered species of all the marine animals. An international committee formed by the Mexican government has established many steps that are aimed and conserving this rare species.
Other international bodies such as the United States, and Canada joined hands with Mexico and established a strategy that was aimed at supporting Mexico in its effort to protect the vaquitas (The Cousteau Society 2010). Vaquitas are considered the most endangered acquired mammal all over the world.
Conclusion
Vaquita is most endangered species of all the marine species. Its existence was recognized in 1958 and since then, most scientists have been interested in the study of the species. The survival of the species is threatened mostly because of the reduction of the flow of water in Colorado River.
Another risk factor includes the use of hydrocarbon pesticides and fertilizer along Colorado River and the use of fishing grills which trap the vaquita. It is therefore clear that urgent conservation measures have to be taken if the population of the vaquitas is to be maintained.
Reference List
Jefferson, T. A, et al (2008). Marine Mammals of the World, a Comprehensive Guide to their Identification. Amsterdam: Elsevier.
Lavín, M.F. & Sánchez, S. (1999). On how the Colorado River affected the hydrography of the Upper Gulf of California. Continental Shelf Research, 19, 1545–1560.
Leatherwood, S., R. et al. (1988). Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic Waters: A Guide to Their Identification. New York: Dover Publications.
Reeves, R. R., et al. (2002). Guide to Marine Mammals of the World. New York: Alfred A. Knopf.
Shirihai, H. & Jarrett, B. (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton: Princeton University Press.
The Cousteau Society (2010). Vaquita Conservation in Mexico. Web.