Thursday, January 07, 2010

Gabon: Manatee Capture!

The frustration had definitely been building. Eight days and nights around the clock setting nets and waiting, having manatees punch holes through the nets every night, second guessing our decisions about where nets should be set, and seeing manatees near the nets everyday, was making us all crazy. Not to mention the heat/humidity, the bugs and the dwindling food supply. Two team members had already had to leave and on the ninth day we knew it was our last day before the rest of the team would start having to depart back to their other lives. So we set out at our usual 5:30am a bit disheartened to say the least.

We checked the first three nets and they were empty as usual. But as we approached the fourth and last net across a small open mangrove lagoon, I noticed that it was bowed at an odd angle, no longer straight into the channel as we had left it. As we came close, stopped the boat engine and began to lift the net to check it, suddenly a manatee nose surfaced right next to one of the buoys! I think we were all in a state of shock, and that shock grew as we saw the manatee and realized it was only caught by its tail, not wrapped around the front part of its body the way they usually get caught. Luckily for us the net was wrapped in a tight knot around the tail and he could not escape. We moved him to shore alongside the boat, moving very slowly so he could breathe. The closest land we could find was an opening in the forest at the edge of the lagoon about a quarter mile away.

The manatee caught by his tail as we first found him in the quiet lagoon. Through the water you can see the net wrapped around his tail.

The manatee was given a complete health assessment including taking morphometrics (standard length and girth measurements), standard photograph views (left side, right side, dorsal, ventral, etc.), body temperature, collection of blood, genetics, fecal, urine, tear, hair and skin lesion biopsy samples. Unfortunately though, the manatee was too small to tag. He was a subadult and the smallest manatee I have recorded in Gabon so far. Manatees need to be a certain size to safely carry the GPS tags, because we don’t want do anything that could cause difficulty for the animal to live its normal life. The point of tagging is not only to track where the manatee moves, but to study behavior. The tags are built with several “weak links” that will break it off the manatee if it gets caught on anything, and they are neutrally bouyant, but they’re still built for adult manatees and this one was just too small. However, the team was excited since this is the first time many of these biological samples have been collected for the species, and this is the first live-captured manatee ever for Gabon.

As usual, a genetics sample was taken by punching a notch in the manatee's tail with a cattle ear notcher. Aside from the valuable information genetics analysis provides about the species, the resulting notch can help identify a manatee that has been peviously captured (if it is caught again in the future).
Standard length and width measurements were also taken, which means we can start to build a database for Gabon's manatees and also compare these measurements to manatees in other parts of Africa. .
I taught Ken how to draw a blood sample from a manatee...

Ken and I posing with the manatee just before we released itReleasing the manatee back into the lagoon

Although time and funding were finished for this round of captures, we were lucky to get one manatee at least, and I hope to be able to try again to tag here in the future.