Today we surveyed the southern margin of our study area around Islas Secas. No humpback whales were seen or heard on the hydrophone. But we received notification from a sports fishing vessel that they had seen them yesterday at Islas Paridas, so that’s where we’re going tomorrow.
We’ve been having excellent weather and we have seen lots of groups of pantropical spotted dolphins during the expedition. They are by far the most common species of cetacean in the Gulf of Chiriquí. We often see them in association with logs and sticks, as they attract small fishes, so the dolphins use them like floating restaurants. Or at least cafés.
We usually take a 15 min break from surveying to eat our sandwich for lunch, while we drift with the engine off to enjoy a moment of quiet. During lunch break today, a pair of spotted dolphins approached us very cautiously. Probably thinking our research vessel Chiripanga was a very big log, they came over to inspect it. Interestingly, only the larger animal in the pair came close, and when the smaller one tried to get close, the larger one pushed it away. We’re guessing this was a mother and her calf and that she was being protective of it. Some days the highlight is the entertainment provided by a momentary lunchtime visitor, be it a yellow-bellied sea snake or an inquisitive dolphin. We’ll gladly take what we get.
Day Eight, March 1, Looking for whales at very low densities, and grateful for hydrophones — our ears in the water
Unlike what some people might imagine our work entails, it is not uncommon for us to spend up to 99% of our time looking at just water. Such days can be tough, as we must remain in full concentration scanning the horizon in order to conduct a rigorous survey.
Fortunately, the Gulf of Chiriquí and its many island groups offer gorgeous vistas of unspoiled nature. And when whales are in very low densities, as is the case in this expedition, we have a secret weapon: the hydrophone.
At the end of a very long day on the water today we were rewarded with humpback whale song coming out of our earphones during the last listening station. We implemented a trial-and-error search pattern for about an hour and a half to locate the lone singer. Ultimately we were unsuccessful in locating him before we had to return home, but in the process we learned a little bit about the range of our hydrophone as well as about how to go about conducting such searches in the future.
We can always hope for visual detections in coming days, but every record of presence is a small victory in this project, and after a few days without whales we were excited to hear them again!
Day Seven, February 28, Low, low tides, and a trip to Islas Contreras — Kingdom of the Bryde’s Whale
This morning we got a little complacent about an early departure, and our trusty research vessel Chiripanga got stuck inside the bay due to the extreme low tides associated with the full moon this time of the month. Since we couldn’t cross the reef, I figured at least I could snorkel it for about an hour until the tide started to come back. I was rewarded with a myriad of beautiful coral reef fishes, and at some point I even had a hawksbill sea turtle AND a much bigger olive Ridley sea turtle swimming together side by side. Where was the GoPro to prove it?!
Our survey today took us to the Islas Contreras, another nearby cluster of islands that harbors great humpback whale densities during the austral season. Today it was empty of humpbacks. We did briefly catch a glimpse of a juvenile whale shark near the surface, and even though we had the GoPro ready this time, it dove quickly as we approached it.
But humpbacks are not the only large whale species that can be found in these waters. Our research in previous years has shown that Contreras is a hotspot for Bryde’s whales, and today it proved itself again: about half way between Secas and Contreras we encountered a pair of Bryde’s whales. Typical for the species, they were rather elusive and we were not able to get close. But at least they kept our skills fresh until we encounter some humpbacks.
We have a network of informants among the fishers and other mariners in the Gulf, and even though we haven’t encountered humpbacks lately, we keep getting reports of others seeing them here and there. So the search continues.
The green circles show the concentration of Bryde’s whale sightings at the Contreras from a previous survey. The figure is from: Rasmussen, K. and D.M. Palacios. 2015. Update on humpback whale research in the Gulf of Chiriqui, western Panama, 2014. Paper SC/66a/SH/16 presented to the IWC Scientific Committee Annual Meeting, May 2015, San Diego, USA. 8pp.https://archive.iwc.int/?r=5500&k=eaf1442d5e
Today we extended our search to the Paridas island group, to the west of our home base at the Islas Secas. Despite excellent weather conditions we had no visual or acoustic encounters. Given the low population size of this group of humpbacks, we are fully expecting very low densities here at the southern extreme of the breeding ground in the Gulf of Chiriquí. So the search goes on.
We are encouraged that our colleagues further to the north are also conducting similar research, including Jose David Palacios Alfaro (Costa Rica), Ester Quintana (Guatemala), and Oscar Frey (Mexico), among several others. We look forward to similar coordinated efforts in future years.
Again, we encountered false killer whales today! This is a rather rare species and it's always a treat to observe their complex behavior and social structure in the wild. Through photographs of the distinctive markings along the trailing edge of the dorsal fin, we were able to determine this was the same group we encountered two days ago. Today we got to photo-ID a few more individuals in the group, and to document the presence of several juveniles.
Also, during the previous encounter, we collected three biopsy samples from this group, and today were able to photo-document the evolution of the biopsy tip wound over the course of two days for one of the animals, showing remarkable healing.
In the process of examining the distinctive markings on the dorsal find and caudal peduncle of these animals, we noticed the unmistakable sign of interactions with fishing gear.
This is a global problem and occurs because this intelligent species has figured out how to steal the catch from hooks set by fishermen. Our captain for this trip, Chanin Bernal, a life-long fisherman in these waters, tells us that artisanal tuna fishermen here in Panama sometimes pull the hooks with only fish heads attached, as the bodies have been snagged by the "pilotos" (the local name for false killer whales and related "blackfish").
Aside from the disfigurement, the problem is that some whales may be getting caught in the hooks or otherwise becoming entangled in the fishing gear, and getting seriously injured or dying
at rates that put local populations at risk (see for example: http://www.fpir.noaa.gov/PRD/prd_false_killer_whale.html).
Tuna and other large predatory fish are economically important for the sports and artisanal fisheries of Panama, and it is evident more work is needed by biologists, managers, and policy makers to solve this global problem that goes largely unnoticed.
Our friends Linda and Jim offered us the opportunity to survey the waters between the Secas and Coiba, an island at the eastern end of the Gulf of Chiriquí, from their larger boat Minerva, and we jumped at the opportunity, as we rarely get to access that area. We had great visual survey conditions and made a few stops to listen for whales, but we didn't encounter any...
...Until we were on the island. Coiba is a national park and its visitor center features the skeleton of a humpback whale and the skull of a Cuvier's beaked whale.
On today’s survey we heard humpback song on several of our listening stations. At one point we also saw the distant blows of what appeared to be a mother/calf pair very close to one of the islands in the Secas group. But the wind chop was picking up and we were unable to relocate them before we had to return to roost for the day. Still, we are happy and encouraged that whales are here, and hope to find more to work within the next few days.
We also enjoyed the company of a mixed aggregation of spotted dolphins and brown boobies, which is a common sight in the Gulf of Chiriquí. And a pretty yellow-bellied sea snake paid us a brief visit while we were stopped for lunch.
Tomorrow our survey will take us to Coiba Island — a former penal colony turned a National Park, and also a famous scuba diving destination. Stay tuned!
Today we surveyed the open ocean while getting familiar with our new captain Chanin, and with our various equipment.
Given the expected low whale density we reduced our survey speed to 9 knots and stopped every 15-20 minutes to listen for humpback whale song. And it paid off: we heard distant song on three of our listening stations, so we know male humpbacks are engaged in courtship behavior here.
We also encountered a group of spotted dolphins early in the morning. But the day’s show was stolen by a large aggregation of false killer whales (Pseudorca crassidens). We first heard their loud whistles on our hydrophone and then saw their large splashes from a distance. We stayed with them for about an hour as we moved from subgroup to subgroup to collect photo-IDs. We also collected three biopsies for DNA studies.
First day on the water today as we arrived in David, exited through the Chiriquí River estuary, and surveyed the waters around two island groups (Paridas and Secas). We didn’t see any whales or hear them on our hydrophones, but saw a small group of spotted dolphins. This area is great whale habitat and hopefully we’ll encounter some in the coming days.
In February 2018 Daniel Palacios of Oregon State Univeristy and Kristin Rasmussen of Panacetacea were in the Gulf Of Chiriquí, Panamá, surveying for humpback whales. Whales seen off Central America between December and April are migrating from feeding areas off California, Oregon and Washington. This population is still considered endangered (thought to number only ~400 animals). The objectives of this study were to document occurrence of humpback whales, presence of calves and singers, and to collecting photo-IDs and biopsy samples. This population was last surveyed in the Gulf of Chiriqui in 2003, 15 years ago. We kept a daily log of our discoveries and highlights of each day. Enjoy!