Info on as to why the west indian manatee is endangered...?

Question

i am doing a project on the west indian manatee (an endangered species) and i need some info as to why they are endangered. i know that one of the reasons is that they tend to have a run in with boat propellers and another reason is that they cannot deal with water pollution.

Answer 1

The West Indian Manatee has been hunted for hundreds of years for meat and hide, and continues to be hunted to this day in Central and South America. Illegal poaching, as well as collisions with speeding motorboats, are a constant source of manatee fatalities.

Due to their low reproductive rates, a decline in manatee population may be hard to overcome. They enjoy protection from the U.S. Endangered Species Act of 1973, and the U.S. Marine Mammal Protection Act of 1972. However, in April 2007, the U.S. Fish and Wildlife Service announced that the West Indian manatee population of Florida had rebounded. It advised that the species be reclassified as "threatened" rather than "endangered".

Federal wildlife officials had to ignore scientific criteria they put in place in 2001 and assume the threats facing manatees will not increase.

A computer model produced for the federal study shows a 50 percent chance that the current statewide manatee population of about 3,300 could dwindle over the next 50 years to just 500 on either coast.[6]

Contrary to what the USFWS has recommended, the Florida manatee subspecies (Trichechus manatus latirostris) has recently (October 2007) been listed as Endangered by the IUCN on the basis of a population size of less than 2,500 mature individuals and a population that is estimated to be in decline by at least 20% over the next two generations (estimated at ~40 years) due to anticipated future changes in warm-water habitat and threats from increasing watercraft traffic over the next several decades. [7]

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Causes of Endangerment

Overexploitation

The manatee has no known predators other than humans. In the past, humans hunted manatees extensively for their meat, fat, and tough hides. In some parts of the Caribbean and South America, manatees are still hunted for food.

Powerboat Collisions

Powerboats are now the greatest threat to manatees. Manatees are slow, near-surface swimmers, and the number of collisions with motorboats is increasing at an alarming rate. In 1990, 218 manatees, which comprised 12 percent of the United States' manatee population, were killed in boating accidents, and many more were injured. A recent project to capture, tag, and release manatees revealed that many bore the scars of encounters with speed boats.

Coastal Development

Residential and commercial development along rivers and waterways has also affected the manatee population. Habitat destruction has damaged the estuarine seagrass communities on which manatees depend. In addition, chemical pollution has impaired the immune systems of marine mammals, and the manatees may have become more vulnerable to infection as a result.

Recent mass deaths among marine mammals have been traced to greater disease vulnerability due to chemical pollution. In 1988, over 10,000 harbor seals died in Denmark and Sweden from a virus related to canine distemper. PCB's (polychlorinated biphenyl) in the water contaminate the fish that the seals eat. The PCB's accumulate in the seals and make them more susceptible diseases. Other pollution-related mass deaths have occurred recently in bottle-nosed dolphins in the Gulf of Mexico (1988) and striped dolphins in the Mediterranean Sea (1991).

Sadly, manatees seem to be experiencing an epidemic too. Since the beginning of 1996, more than 250 manatees have been found dead in southwestern Florida. With their population already severely reduced due to other causes, a single epidemic such as this could push the manatee beyond the point of no return, into an extinction vortex.

The spread of the disease may be facilitated by the gathering of manatees at the warm-water outflows of power plants. "It's a horrible tragedy," says Florida governor Lawton Chiles. "This is the single worst die-off we've ever seen with an endangered species in this state."

Conservation Actions

Protected Areas

Manatees have been protected for an unusually long time. The English declared Florida a manatee sanctuary in the 1700s and hunting manatees was prohibited. Sanctuary from hunters has not protected the manatee from speed boats, however. Speed limits in waterways can help manatees by giving them enough time to avoid collisions and reducing the severity of collisions when they do occur.

Tourism

Manatees spend hours grazing underwater everyday, and they can be very exciting to watch in their natural habitat. Manatee-watching tourism gives local people a financial incentive to preserve the species, since tourists spend their dollars at local businesses. Tourists may be inspired to do something to help these beautiful and mysterious creatures.

In Belize, manatee-watching tourism has been a very successful conservation action. Not long ago, local people hunted manatees with rifles, while today manatees are a big attraction for tourist dollars. Unfortunately, the boats that take passengers out to view the manatees have become an increasing threat. Collisions with motor boats are becoming more common and are an increasing cause of manatee mortality in Belize.

Research

More scientific research is needed to understand manatees and their needs. One current study is tracking manatees by satellite to learn more about where they go and what they do. We need to know more about their calving and feeding behaviors.

Citizen Involvement

Citizens are helping to preserve manatees through the Save the Manatee Club, an organization co-founded by singer-songwriter Jimmy Buffet. Citizen involvement also has been an important factor in tracking the recent wave of manatee deaths in Florida. Reports from concerned people are helping scientists study and understand the causes and effects of the epidemic.