Tuesday, November 24, 2015

Great Whale Gatherings - Part 4

Part 4: The Sperm Whale Super-pods

Sperm Whale © Gehan de Silva Wijeyeratne

In this last part of this multi-part article, I continue with the story of Sperm Whales and in particular on the super-pods recorded off Sri Lanka.
The Sperm Whale is the great whale, which is typically a social animal and famed for large concentrations in the whale literature from the 19th to 21st centuries. It is the ‘Elephant of the Sea’; females and immature males form breeding schools in the tropics and live in social units. However, in my article in the Sunday Times (Sri Lanka) I explained that the references in many popular books on whales, of thousands of Sperm Whales being seen together suggested as being normal is incorrect. This is an erroneous interpretation of Hal Whitehead’s book where he estimates that approximately 750 Sperm Whales may be found in a concentration spanning 300km and in discussing the impact of modelling assumptions states ‘.....while one 500km across would have about 22,000'. I suspect the discussion on modelling and the impact of assumptions on statistical measures have resulted in other writers misinterpreting that it is normal to see Sperm Whales in the thousands. The mean pod sizes listed in Whitehead’s book range from 18 to 29.8. In conversation with him and other scientists and professionals in whale watching, I clarified that a pod of over 40 Sperm Whales is something special. Since then, inspired by my encounters with large pods of Sperm Whales in Mirissa, Kalpitiya and Trincomalee, I have been seeking data from whale watching guides and boat operators in Sri Lanka for continuing evidence of this claim.
In addition to the annual super-pods, the key evidence so far of large gatherings off Sri Lanka is a Sperm Whale gathering recorded in March 2012 and another recorded on 29th September 2014. In 2012, a super-pod was observed between 8th March and 27th March, which had more than 40 individuals together during this period. Nilantha Kodithuwakku and Buddika (‘Daya’) Dhayarathne, two naturalists of Cinnamon Nature Trails who were resident at Chaaya Blue, a John Keells Hotel, took clients out to view and or dive with the whales. Client estimates varied, from Amos Nachoum estimating around 60-80 to Andrea Steffen, who has studied Sperm Whales off Dominica, estimating over a hundred. I had extensive face-to-face discussions with Nilantha and Daya on two separate visits to Sri Lanka to gain clarity on the March 2012 super-pod. They noted that on 4 days from 20th March to 23rd March 2012, the numbers on the ocean surface in the field of view peaked at approximately 200 to 250. This is a phenomenal concentration or gathering, as this was a surface count based on what they thought they could see around them.
Over two years later, on 29th September 2014, Daya encountered the largest aggregation of Sperm Whales he had ever seen with an estimate of over 300 Sperm Whales. I discussed this in detail with him by phone. He had travelled about 8km offshore from Trincomalee and then travelled around 13km towards Pigeon Island. He encountered 12-13 pods of Sperm Whales each containing 20-30 on the surface. Chitral Jayatilake who leads the team of Cinnamon Nature Trails naturalists arranged to fly out the next day to photograph this large gathering of Sperm Whales. Daya headed out to sea to locate the whales and relay the GPS coordinates, but the Sperm Whales were gone, although Daya did see an estimated eight Blue Whales on that day. Between March 2014 and September 2014, Daya had regularly encountered small pods of Sperm Whales at sea, up to the date of the large gathering referred to above. He speculates that the whales had gathered before moving out of the area together and he did not see them until March 2015.
The Sperm Whale super-pod data I have shows that super-pods occur regularly. These are summarised by month and location and by year and location in the accompanying tables. But note that the number of days seen is not the same as individual super-pods. The March 2012 super-pod in Trincomalee was seen on 20 days and may have comprised of many of the same whales although it is possible that in these gatherings there could be turnover of the specific individuals present from one day to another [1, 2, 3].
The most significant super-pods besides the two already mentioned include the following: between 16th to 18th April 2013 in Kalpitiya a super-pod seen by various observers with some estimates over 100 but conservatively estimated at 70, on 9th March 2013 a super-pod estimated between 150 to 200 by various observers off Mirissa, on 12th March 2013 an un-confirmed report by fishermen (relayed by Ashan Seneviratne) of a super-pod of 200 in Kalpitiya (the count needs to be treated with caution; but may have been large and is noteworthy given the sighting in Mirissa a few days earlier), on 22nd March 2013 a super-pod of 100 off Mirissa relayed by Tony Wu who had an underwater image which showed 23 Sperm Whales in one frame, on 15th March 2014 a super-pod of 75 seen by Dr. Charles Anderson in Trincomalee, on 11th May 2014 a super-pod of 70 seen by Nilantha Kodithuwakku (conveyed by Georgina Gemmell) off Trincomalee, and on 24th March 2015 a super-pod with a surface count of 110 plus stragglers seen off Kalpitiya by a team including personnel from Whale and Dolphin Conservation (WDC). The last observation was released in social media as possibly the largest gathering of Sperm Whales seen in living memory and the count was estimated at between 350-500 (but this included whales estimated at being present under water). Based on the surface count relayed to me by email, this observation was more likely to have been on par with the super-pod of 16th -18th April 2013 in Kalpitiya. On the basis of comparable surface counts, it is not the largest seen off Sri Lanka or in living memory.
The significance of these large Sperm Whale super-pods can be seen in context in the following comments I received in response to my article in the Sunday Times (Sri Lanka) on 5th August 2012. Tony Wu, an award winning underwater photographer wrote to me on 8th August 2012. “I have seen groups of up to 20 or so animals in Japanese waters, but never up to 40-50 as you report. I talked with my friends who pioneered the Sperm Whale watching industry in Ogasawara, Japan, where I photographed the Sperm Whales eating giant squid. They have been observing Sperm Whales since the mid-90s in that area, and are probably the most experienced Sperm Whale people in Japan. They confirmed that they have only seen up to around 20 animals in a given group....’. Michael Fishbach (Great Whale Conservancy) wrote on 5th August 2012. “I think I can clarify what you wrote about the Sea of Cortez and Sperm Whales. During my Blue Whale work there over the past 18 years the biggest pod of Sperm Whales I have encountered is an estimated 70. Amazing and unforgettable are two words I can associate with that encounter. The Azores is another location famed for its Sperm Whales. In a paper by Sara Magalhaes and others published in 2002 in the journal ‘Aquatic Mammals’ on reactions of Sperm Whales to whale watching vessels, they published details of pod sizes observed. In 69 land-based sightings, group size averaged 3.1 with the maximum being five. On 40 sightings in boat-based observations, the mean group size was again 3.1 with a maximum of seven. Compare this with Sri Lanka where super-pods are annually encountered which comprise of more than 40 whales.
The naturalists who take people whale watching off Sri Lanka are often pre-occupied with handling clients and it is possible that the numbers in super-pods are under-counted, or that when clients spend time with one pod of Sperm Whales, other pods in the close vicinity may be missed unlike in a scientific survey using a line transect method. But the two observations in March 2012 and in September 2014, together with the other observations, underline how important the waters off Sri Lanka are for large concentrations of these great whales. The large numbers present off Sri Lanka’s waters are probably a result of the nutrient flows arising from upwellings from the two monsoons, nutrient flow from the Indian mainland and the 103 river systems in Sri Lanka. In February 2012, a team from the Ceylon Bird Club during an annual waterfowl census estimated over a million shorebirds from a single point of view in Mannar. This is probably the largest flock of migrant shorebirds counted from a single viewpoint. The nutrient dynamics which support large numbers of wintering migrants are probably the same which support the presence of Blue and Sperm Whales in Sri Lankan coastal waters.
An analysis of 19th century whaling logbooks by Charles Townsend covering 1,665 voyages published in Zoologica, the journal of the Zoological Society of New York was accompanied by four charts, which showed the locations of where whales were hunted. This clearly shows that the New England whalers took Sperm Whales off Sri Lanka but not to the degree elsewhere. It is also possible that the Sperm Whale aggregations off Sri Lanka escaped the brunt of the 20th century whaling. However, the Northern Indian Ocean Blue Whales were subject to intense illegal Soviet whaling. Whether it was less whaling pressure or nutrient dynamics, or both, Sri Lanka is now a custodian of an important world heritage of great whale aggregations.
Let me conclude this multi-part article. Although, in popular parlance there are references to large aggregations of Right Whales, Minke Whales, Humpback Whales and Bowhead Whales they do not seem to be occurring frequently enough, predictably enough and in large enough numbers to be a visual spectacle for it to be an wildlife tourism event. In terms of visual effect, a super-pod of Sperm Whales off Sri Lanka may well carry the biggest visual impact. However, this is not predictable enough to become a commercially viable wildlife event. The large aggregations of Grey Whales are predictable in timing of year and location and the tourism infrastructure is in place. The large aggregation appears to be spread out so that tourists are not confronted with the visual spectacle of a large gathering of large animals as with the Elephant Gathering in Sri Lanka where over 100 elephants are frequently in the field of view from a single point. Nevertheless, it seems that the Grey Whales of Laguna San Ignacio and Laguna Ojo de Liebre, best meet the description of the greatest gathering of great whales. In 2011, the magazine Wild Travel published a special issue on the ‘100 natural wonders that everyone should see in their lifetime’. The Grey Whale gathering in the nursery lagoons was missing. I suspect because there is no branding that there is no realisation that besides the amazing intimacy of being able to touch Grey Whales, in these lagoons are also the Greatest Gathering of Great Whales, which are annually recurrent and commercially viable for tourism. I would anticipate that for ‘Conservation through Commerce’ to work, this tagline will be adopted by those seeking to take tourists out there as well as those who need to raise grants for science and conservation.
A number of individuals have assisted in many ways. None of them necessarily share the views I have made in this article and any mistakes or errors of opinion remain mine. Mark Carwardine was very helpful in challenging my first draft and encouraging me to extend the scope of the article. Robert Pitman, Hal Whitehead, Charles Anderson and Georgina Gemmell commented on early drafts. Tara Wikramanayake made numerous copy edits. A number of individuals answered questions, provided information, made helpful introductions or shared and gave useful points to ponder. These include Robert Pitman, William Perrin, Trevor Branch, Doug Butterworth, Mark Bravington, Paul Ensor, Paula Olson, Elke Burkhardt, Koji Matusoka and Matt Curnock. Lauren Horncastle tidied citations for me. Gabriel Jamie scanned the original letter by W.D. Boyer and the response to it from the University of Cambridge library. Mark Bravington shared a data summary from the IWC cruises which helped me to better articulate a request to the IWC. Kate Wilson and Marion Hughes provided data from the IWC database. Vanessa Williams-Grey emailed me soon after her field observation of the Sperm Whale super-pod sighting in April 2015 and in the subsequent dialogue Hal Whitehead drew attention to Boyer’s published account. Many people have over the years shared their data with me and were individually acknowledged in my previous article on Sperm Whale super-pods. I owe special thanks to Buddika (‘Daya’) Dhayarathne and Nilantha Kodituwakku who have shared their sightings, especially from Trincomalee, with me. My thanks also Joshua Barton, Matt Curnock and Chris Breen who provided images and additional information.
Papers consulted in the multi-part article Greatest Gatherings of Great Whales
In this multi-part article in Wall Street International, I have sought to answer the question of where the greatest great whale gatherings have occurred or continue to occur. I consulted a number of people and read a number of scientific papers. The people who have helped me in various ways are mentioned in the acknowledgements. This multi-part series article will be a useful reference to media, whale watchers and others with an interest in marine biology. I have therefore included this supplementary bibliography which includes the citations of the papers I consulted. Only papers which are relevant in the context of information on large, great whale aggregations are listed here. To make it easier for a non-scientific audience, the citations are grouped by type of whale rather than in the usual alphabetical manner in a formal publication.
Bowhead Whales
(1). Born, E. W. and Heide-Jørgensen, M. P. (1983). Observations of the bowhead whale (Balaena mysticetus) in central West Greenland in March-May 1982. Rep. Int. Whal. Comm. 33, pp 545-547.
(2). Hansen, R.G., Heide-Jørgensen, M. P. and Laidre, K. L. (2012). Recent abundance of bowhead whales in Isabella Bay, Canada. Journal of Cetacean Research and Management. 12 (3), pp 317-319.
(3). Heide-Jørgensen, M. P., Laidre, K. L., Wiig, Ø., Postma, L., Dueck, L. and Bachmann, L. (2010). Large-scale sexual segregation of bowhead whales. Endangered Species Research, 13, pp 73-78.
(4). Heide-Jørgensen, M. P., Laidre, K. L., Borchers, D., Samarra, F. and Stern H. (2007). Increasing abundance of bowhead whales in West Greenland. Biology Letters, 3, pp 577-580.
(5). Landino, S. W., Treacy, S. D., Zerwick, S. A. and Dunlap, J. B. (1994). A Large Aggregation of Bowhead Whales (Balaena mysticetus) Feeding near Point Barrow, Alaska, in Late October 1992. Arctic, 47 (3), pp 232-235.
(6). Moore, S. E., George, J. C., Coyle, K. O. and Weingartner, T. J. (1995). Bowhead Whales along the Chukotka Coast in Autumn. Arctic, 48 (2), pp 155-160.
(7). Reeves, R. R. and Heide-Jørgensen, M. P. (1996). Recent status of bowhead whales, Balaena mysticetus, in the wintering grounds off West Greenland. Polar Research 15 (2), pp 115-125.
Fin Whales
(8). Acevedo, J., O’Grady, M. and Wallis, B. (2012). Sighting of the fin whale in the Eastern Subtropical South Pacific: Potential breeding ground? Revista de Biología Marina y Oceanografía 2012, 47, pp 559-563.
(9). Burkhardt, E. and Lanfredi, C. (2012). Fall feeding aggregations of fin whales off Elephant Island (Antarctica). IWC SC paper SC/64/SH9 (unpublished).
Gray Whales
(10). Swartz, S.L., Urbán R., J., Gómez-Gallardo U., A., Martínez, S., Robles M, J.I., López, I.G. & Rojas-Bracho, L. (2013). Numbers of Gray Whales (Eschrichtius Robustus) utilizing Laguna San Ignacio, Baja California Sur, Mexico during The Winter Breeding Seasons: 2007-2013. Rep. Intl. Whaling Commission, Scientific Committee SC/65a/BRG06.
Humpback Whales
(11). Anonymous. (2010). Advice relevant to the identification of critical habitats for north pacific humpback whales (Megaptera novaeangliae). DFO Canadian Science Advisory Secretariat Science Response, 2009/016. Fisheries and Oceans Canada Science.
(12). Ashe, E., Wray, J., Picard, C. R. and Williams, R. (2013). Abundance and survival of Pacific humpback whales in a proposed critical habitat area. PLoS ONE 8(9): e75228.
(13). Johnston, D. W., Friedlaender, A. S., Read, A. J. and Nowacek, D. P. (2012). Initial density estimates of humpback whales Megaptera novaeangliae in the inshore waters of the western Antarctic Peninsula during the late autumn. Endangered Species Research, 18, pp 63-71.
(14). Nowacek, D. P., Friedlaender, A. S., Halpin, P. N., Hazen, E. L., Johnston, D. W., Read, A. J., Espinasse, B., Zhou, M. and Zhu, Y. (2011). Super-Aggregations of Krill and Humpback Whales in Wilhelmina Bay, Antarctic Peninsula. PLoS ONE 6: e19173 doi: 10.1371/journal.pone.0019173
(15). Waite J. M., Dahlheim, M., Hobbs, R. and Mizroch, S. (1999). Evidence of a feeding aggregation of humpback whales (Megaptera novaeangliae) around Kodiak Island, Alaska. Marine Mammal Science 15 (1), pp 210–220.
(16). Witteveen, B. H., Wynne, K. M. and Quinn II, T. J. (2007). A Feeding Aggregation of Humpback Whales Megaptera novaeangliae near Kodiak Island, Alaska: Historical and Current Abundance Estimation. Alaska Fishery Research Bulletin, 12 (2).
(17). Fisheries and Oceans Canada. (2013). Recovery Strategy for the North Pacific Humpback Whale (Megaptera novaeangliae) in Canada. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada, Ottawa. x +pp 67.
Minke Whales
(18). Branch, T. A. (2006). Abundance estimates for Antarctic minke whales from three completed circumpolar sets of surveys, 1978/79 to 2003/04. IWC SC paper SC/58/IA18 (unpublished).
(19). Branch, T. A. (2014). Southern Hemisphere minke whales: standardised abundance estimates from the 1978/79 to 1997/98 IDCR/SOWER surveys. Journal of Cetacean Research and Management, 01/2001 (3), pp 143-174.
(20). Hirohisa, K., Hidehiro, K., Fujio, K. and Yoshihiro, F. (1991). Detection of heterogeneity and estimation of population characteristics from the field survey data: 1987/88 Japanese feasibility study of the southern hemisphere Minke whales. Annals of the Institute of Statistical Mathematics September 1991, 43 (3), pp 435-453.
(21). Kasamatsu, F., Ensor, P. and Joyce, G. G. (1998) Clustering and aggregations of minke whaIes in the Antarctic feeding grounds. Marine Ecology Progress Series, 168, pp 1-11.
(22). Kasamatsu, F., Nishiwaki, S. and Ishikawa, H. (1995). Breeding areas and southbound migrations of southern minke whales Balaenoptera acutorostrata. Marine Ecology Progress Series, 119, pp 1-10.
(23). Kelly, N., Peel, D. and Bravington, M. V. (2014). Distribution and abundance of Antarctic minke whales in sea ice regions of East Antarctica: a summary of results. IWC SC paper SC/65b/IA15 (unpublished).
(24). Matsuoka, K., Ensor, P., Hakamada, T., Shimada, H., Nishiwaki, S., Kasamatsu, F. and Kato, H. (2003). Overview of minke whale sightings surveys conducted on IWC/IDCR and SOWER Antarctic cruise from 1978/79 to 2000/01. Journal of Cetacean Research and Management, 5 (2), pp 173-201.
(25). Murase, H., Kitakado, T., Matsuoka, K., Nishiwaki, S. and Naganobu, M. (2007). Exploration of GAM based abundance estimation method of Antarctic minke whales to take into account environmental effects: A case study in the Ross Sea. IWC SC paper SC/59/IA12 (unpublished), pp 13.
(26). Shimada, H. and Kato, A. (2005). Preliminary report on a sighting survey of Antarctic minke whale within ice field conducted by the Ice Breaker, Shirase in 2004/2005. IWC SC paper SC/57/IA7 (unpublished), pp 14.
Dwarf Minke Whales
(27). Birtles, A., Valentine, P., Curnock, M., Mangott, A., Sobtzick, S. & Marsh, H. (2014). Report to the Great Barrier Reef Marine Park Authority on the Dwarf Minke Whale Tourism Monitoring Program (2003­2008). Research Publication No. 112. Great Barrier Reef Marine Park Authority.
(28). Sobtzick, S. (2010). Dwarf minke whales in the northern Great Barrier Reef and implications for the sustainable management of the swim-with whales industry. PhD thesis, James Cook University.
Right Whales
(29). Failla, M., Vermeulen, E., Carabajal, M., Arruda, J., Godoy, H., Lapa, A., Mora, G., Urrutia, C., Balbiano, A. and Cammareri, A. (2008). Historical records of southern right whales (Eubalaena australis) of the province Río Negro, North Patagonia, Argentina (1991-2008). IWC SC paper SC/60/BRG1 (unpublished).
(30). Anonymous. (2012). Known Biologically Important Areas for Cetaceans Chukchi Sea and Alaskan Beaufort Sea. Represents work done by Janet Clarke of Science Applications International Corporation, with review and revisions contributed by the Cetacean Mapping Working Group members.
(31). Branch, T. A. and Butterworth, D. S. (2014). Estimates of abundance south of 60°S for cetacean species sighted frequently on the 1978/79 to 1997/98 IWC/IDCR-SOWER sighting surveys. Journal of Cetacean Research and Management, 3 (3), pp 251-270.
(32). Clarke, R. (1962). Whale observation and whale marking off the coast of Chile in 1958 and from Ecuador towards and beyond the Galapagos Islands in 1959. Norsk Hvalfangst-tid. 51 (7), pp 265-287.
(33). Ensor, P., Komiya, H., Beasley, I., Fukutome, K., Olson, P. and Tsuda, Y. (2007). 2006–2007 International Whaling Commission-Southern Ocean Whale and Ecosystem Research (IWC-SOWER) cruise. IWC SC paper SC/59/IA1 (unpublished).
(34). Ensor, P., Minami, K., Morse, L., Olson, P. and Sekiguchi, K. (2008). 2007-2008 International Whaling Commission-Southern Ocean Whale and Ecosystem Research (IWC-SOWER) cruise. IWC SC paper SC/60/IA1 (unpublished).
(35). Matsuoka, K., Hakamada, T., Kiwada, H., Murase, H. and Nishiwaki, S. (2005). Abundance Increases of Large Baleen Whales in the Antarctic based on the Sighting Survey during Japanese Whale Research Program (JARPA). Global Environmental Research 9 (2), pp 105-115.
(36). Matsuoka, K., Watanabe, T., Ichii, T., Shimada, H. and Nishiwaki, S. (2003). Large whale distributions (South of 60°S, 35°E-130°E)in relation to the southern boundary of the Antarctic Circumpolar Current. eds Huiskes, A.H.L., Gieskes, W.W.C., Rozema, J., Schorno, R.M.L., van der Vies, S.M. and Wolff, W.J. Antarctic Biology in a Global Context. Backhuys Publishers, Leiden 3, pp 26-30.
(37). Nishiwaki, S., Ogawa, T., Matsuoka, K., Mogoe, T., Kiwada, H., Konishi, K., Kanda, N., Yoshida, T., Wada, A., Mori, M., Osawa, T., Kumagai, S., Oshima, T., Kimura, K., Yoshimura, I., Sasaki, T., Aki, M., Matsushita, Y., Ito, H., Sudo, S. and Nakamura, G. (2007). Cruise report of the second phase of the Japanese Whale Research Program under special permit in the Antarctic (JARPA/JARPAII) in 2006/2007 –feasibility study- IWC SC paper SC/63/O4 (unpublished).
(38). Scheidat, M., Friedlaender, A., Kock, K.H., Lehnert, L., Boebel, O., Roberts, J. and Williams, R. (2011). Cetacean surveys in the Southern Ocean using icebreaker-supported helicopters. Polar Biology 34, pp 1513–1522.