Tuesday 9 November 2021

Coral reefs

 Did you know that more wildlife lives around coral reefs than in any other part of the ocean? Find out more about these important ecosystems in our coral reef facts…

What are coral reefs?

When you look at a coral reef, you might think that you are seeing a group of colorful rocks. But don’t be mistaken! Reefs are actually made out of living creatures called coral.

Tuesday 14 October 2014

Aere ra to'ora

Nan and the team have put together the below (epic!) video capturing many of the highlights of our 2014 tagging research.  Enjoy!

Migration Update #5

I don't know about you, but I sure couldn't row a boat that straight for that long in the open ocean. Check out the map!

121195.14 is our big mover of the week! 500+ km along a bearing that is straight as...
That's roughly the meridional width of Wyoming or Colorado, and I bet this whale is
swimming straighter than most folks drive on I-70.
More in depth analysis to come - as soon as I finish teaching for the year this week.

All the best and thanks for still following along!


Tuesday 7 October 2014

Migration Update #4

Has the migration finally begun?

It seems most of our tagged whales are perfectly happy continuing to bounce between the islands of Oceania. 112716.14 continues to hang out around the small islands of northern Tonga, 112697.14 has joined the party in Samoa, and 87777.14 has shifted over to Atiu from Aitutaki in the southern Cook Islands.

121195.14 is the whale I have my eye on most at the moment. It has started swimming away from Samoa in an overall southeasterly direction. It could very well stop-over in Niue over the next few days - or it might very well keep on going all the way to the Antarctic. We'll have to wait and see if the southward migration has well and truly (finally!) begun, or if this is just another (truly remarkable!) example of island hopping...

Oct. 7, 2014 Humpback Whale Track Map 

I've updated the cumulative distance graphic as well (see below), in addition to the satellite transmission pie charts (further below). The cumulative distance plot continues to show that the open-water movements are faster than the near-shore movements - eventually I will do a piecewise linear regression breakpoint analysis on these distance versus time plots to objectively identify changes in the behavioural states of the whale movements (free from all the problems of state-space modeling and other forms of interpolation!). Meanwhile, the satellite transmission pie charts haven't changed very much (despite there being three times as many total transmissions received since my last update). This indicates to me that the current pattern of transmission quality/distribution should continue as long the whales stay in this sector of the South Pacific Ocean. As the whales start moving out of Oceania, however, the satellite transmission window gets broader and we might very well see an increase in the quality/number/distribution of the transmissions received. Maybe next week...

Cumulative Distance traveled versus time plot. Steeper slopes equate with faster open-water movements, lower slopes equate with slower near-shore movements.

An update to the Argos satellite transmission distributions and location data quality (for those techno-gearheads out there; Hi, Dad!)
And speaking of Papi (what the Grandkids call my Dad - who is also named Travis), I have changed the 'inferred' path taken by 87777.14 in the updated map at the top of this post. I agree, Papi. There's no evidence to suggest 87777.14 took such a tortuous (i.e. sinuous) course during the period that it's transmitter tag went silent. All the other data would suggest that something more like the inferred (yellow dashed) path shown in the map above is more likely (than what I had previously inferred). That said, we'll never be able to prove it one way or another...

I'm gonna getcha. Gonna getcha, getcha, getcha, getcha, next week. Or another. Gonna find ya...

Monday 29 September 2014

Migration Update #3

We have passed the one-month mark since deployment of our first tag and what a month it has been!

One month ago we did not know how 'easily' humpback whales commute between the islands of Oceania. ['commuting' is a type of animal movement behavior distinct from migration, homing, dispersing, etc.]

One month ago we did not know that the migratory corridor between Rarotonga and American Samoa was so popular. [112697.14 and 120946.14 are swimming the route as at least a pair as I type!]

One month ago we did not know that humpback whales would swim more than 2000km across the tropics - roughly one-half the distance to the closest feeding grounds - only to come back to the same place they were at three weeks earlier! [this makes little sense considering the lack of food in tropical waters]

Rarotonga Humpback Whale Satellite Track Map - Sept. 29, 2014

Meanwhile, Nan and the team SOMEHOW have recovered tag #87625 - the one that got deflected by a wave just as it was about to deploy! Last I heard, it was sitting on 46 meters down just outside Avana Harbour, when all of a sudden - PING! - a location shows up on my Argos satellite map. Unreal.

I've been doing all I can to educate and raise awareness regarding Oceania's endangered humpback whales (when not checking Argos or teaching here at U.Canterbury). The kind folks at the U.S. Embassy in Wellington, New Zealand even invited me to give them an interview on our research. Thanks much Jamiela, Michael, Laura, Ola, Tracey, Rob, Candy and all the good people at the embassy! You can link to the interview below (it's 20 minutes long - what can I say...I'm excited!).

Tuesday 23 September 2014

Migration Update #2

Another week, another 1000 km...

It's been an exciting 7 days since my last Megaptera14 humpback whale migration update! One transmitter tag has come back to life, one whale has been content cruisin' around Raro, and 4 others have made haste to new island homes. The data never cease to amaze me!

Tag #87777.14 just started transmitting locations again after a two-week hiatus. Last we heard from 87777.14, "he" was headed north away from Rarotonga. Approximately 21 hours ago, 87777.14 started sending transmissions again and it's looking like he misses Nan and the team - he's heading back towards Raro from ~700km due west of the island!

23 Sept, 2014 update of humpback whale movements.

Since transmissions stopped on Sept. 8, 2014, it's anyone's guess what 87777.14 got up to. I have sketched in an ~1735 km long circuit route on the above map in yellow dashes. At an average traveling velocity of 5 km/hr over the 347 hour-long gap in transmissions, 87777.14 would have swam 1735 kilometers - the same distance as the yellow-dash circuit route.

However, if I had to bet on where 87777.14 actually went, my money would be on Manu'a (American Samoa). It's highly unlikely that it swam any faster than 6 km/hr for any extended period of time (this based on both the 2007 and 2014 swimming speeds observed for other humpbacks in the region). That would make 87777.14's maximum total distance traveled ~2100 km for the period between Sept. 8 and Sept. 23, 2014. It could have made it all the way to Upolu, but it wouldn't have had any time hang-out once it arrived there. The only other islands it could have reached, and had time to cruise, are Palmerston and Niue. Where do you think 87777.14 went?

Most of the other whales seem content hanging/cruising around new island homes. 112726.14 has spent time around both Niue and Vava'u (but it's now heading south-southwest parallel to the Tonga Trench!). 121195.14 has been around Manu'a for a few days now, and 81126.14 has stayed true to the Cooks and has been cruising around Atiu way for several days. 112697.14 is our home-body - it's still around Raro, and 120947.14 is my favorite because it followed the same ~550 km long 'straight as' track as 2007 tag #37282.07 (highlighted by the red ellipse in the above map).

It's absolutely exhilarating logging in to the Argos system and down-loading these data every day! These tracks are revealing several new and exciting things about humpback whale movement behavior and I do hope they keep on transmitting for many days to come. Stay tuned...

Thursday 18 September 2014

For Your Viewing Pleasure...

...I've prepared some YouTube clips. These are not just regular old home movies, folks. These are truly spectacular images that capture some magical moments. Enjoy!

I'll post an update on the whale movements in a few days. Thanks for following along!