Manatee Mortality in 2008

There are mixed messages from the recent data on manatee morality 2008, recently released.

Here is a good article:

Manatee Tampa Bay.com

Interesting:

Manatee total deaths up from last year by about 20; but not near the high of 417 in 2006, some of which was attributed to red tide outbreaks in 2006. There wasn't much red tide in 2008, which makes me concerned that the number of total deaths is still so high above the 300 mark?

Manatee boat-related fatalities were 90 in 2008, down from the highs of 95 and 92 over the past several years.

But the most disturbing is that a record number of infant manatee carcasses were recovered, 101. In 2007 the number was 59 infant mortalities. That is up almost 60%! An explanation is given that possibly just more baby manatee were born and more carcasses were found and recovered? Possibly, but nearly 60% up is a lot. From what I observed we had several early cold fronts during the 2007/2008 season, and especially quite a few late cold fronts that forced mother manatee to give birth in places that were less than ideal, i.e., cooler water areas, very shallow water zones and areas with a lot of other manatee present. I wonder if these things also contributed to the high infant mortality? I personally saw other manatee trying to gain possession of an infant manatee by separating it from its mother, then playing with the infant like it was some sort of toy. Additionally a friend of mine observed a pre-mature manatee infant being batted around by a young male manatee, like a football. These are the types of things that can happen when mothers don't have the ability to choose to go to an out-of-the-way place and give birth. But then of course if mother is killed in a boat-related incident then baby is many times recovered as a carcass soon after. I'm sure there are lots of reasons for the rise in infant mortality, but a 60% rise is disturbing, even given the possibility that just more infants were born in 2008?

So what I gather from this report is the only good news is that manatee deaths were below the 5 year average of around 359/yr, but that is mostly because of less red-tide related deaths in 2008. I don't see much of anything positive about these statistics on the whole.

Show's there is still a lot of work to be done. And hopefully the record infant mortality stats just indicate more manatee being born (which would be good news!!). Hopefully that is the case.

Carol

There are mixed messages from the recent data on manatee morality 2008, recently released.

 

Here is a good article:

Manatee Tampa Bay.com

 

Interesting:

Manatee total deaths up from last year by about 20; but not near the high of 417 in 2006, some of which was attributed to red tide outbreaks in 2006. There wasn't much red tide in 2008, which makes me concerned that the number of total deaths is still so high above the 300 mark?

 

Manatee boat-related fatalities were 90 in 2008, down from the highs of 95 and 92 over the past several years.

 

But the most disturbing is that a record number of infant manatee carcasses were recovered, 101. In 2007 the number was 59 infant mortalities. That is up almost 60%! An explanation is given that possibly just more baby manatee were born and more carcasses were found and recovered? Possibly, but nearly 60% up is a lot. From what I observed we had several early cold fronts during the 2007/2008 season, and especially quite a few late cold fronts that forced mother manatee to give birth in places that were less than ideal, i.e., cooler water areas, very shallow water zones and areas with a lot of other manatee present. I wonder if these things also contributed to the high infant mortality? I personally saw other manatee trying to gain possession of an infant manatee by separating it from its mother, then playing with the infant like it was some sort of toy. Additionally a friend of mine observed a pre-mature manatee infant being batted around by a young male manatee, like a football. These are the types of things that can happen when mothers don't have the ability to choose to go to an out-of-the-way place and give birth. But then of course if mother is killed in a boat-related incident then baby is many times recovered as a carcass soon after. I'm sure there are lots of reasons for the rise in infant mortality, but a 60% rise is disturbing, even given the possibility that just more infants were born in 2008?

 

So what I gather from this report is the only good news is that manatee deaths were below the 5 year average of around 359/yr, but that is mostly because of less red-tide related deaths in 2008. I don't see much of anything positive about these statistics on the whole.

 

Show's there is still a lot of work to be done. And hopefully the record infant mortality stats just indicate more manatee being born (which would be good news!!). Hopefully that is the case.

 

Carol

Carol,

What is the data on total manatee population, and what should be a 'normal' manatee death and birth rate on a year to year basis. It would be helpful if one could understand this on a percentage basis as to whether the manatee population is contracting or expanding, and by how much.

Carol,

What is the data on total manatee population, and what should be a 'normal' manatee death and birth rate on a year to year basis. It would be helpful if one could understand this on a percentage basis as to whether the manatee population is contracting or expanding, and by how much.

Jeff, good ?

If 10% of the total population dies in a year the species is considered at risk of being unable to sustain itself.

The interesting Florida Fish and Wildlife Research Institute Article, 'Synoptic Survey Conditions for Winter 2008' shows the difficulties in counting the population from 1991-2007. 2008 counts had to be scrapped because of weather that was too warm to accurately count the population.

If the 2008 mortality total is above 10% of the total manatee population, there is no sure way of knowing as there is no sure way of getting a fully accurate manatee count. But it seems that 2008 deaths of 337 is more than 10% of the total population and is considered unsustainable.

Here is a quote from another local St Pete Times 2008 manatee mortality article, specifically addressing the infant deaths:

"Although no one knows for sure how many manatees swim in Florida's waterways, in 2001 scientists counted 3,300 of them, the most ever. Subsequent counts found lower numbers."

Carol