Dhofar IMMA

Size in Square Kilometres

19 168 km2

Qualifying Species and Criteria

Indian Ocean blue whale – Balaenoptera musculus indica

Criterion A; C (ii)

Bryde’s whale – Balaenoptera edeni

Criterion A; C (i, ii)

Humpback whale – Megaptera novaeangliae

Criterion A; B (ii); C (i,ii)

Sperm whale – Physeter macrocephalus

Criterion C (i,ii)

False killer whale – Pseudorca crassidens

Criterion C (i)

Indian Ocean humpback dolphin – Sousa plumbea

Criterion A

Marine Mammal Diversity 

Criterion D (ii)

Balaenoptera edeni, Balaenoptera musculus indica, Delphinus delphis tropicalis, Globicephala macrorhynchus, Grampus griseus, Kogia sima, Megaptera novaeangliae, Orcinus orca, Peponocephala electra, Physeter macrocephalus, Pseudorca crassidens, Sousa plumbea, Stenella longirostris, Steno bredanensis, Tursiops aduncus, Tursiops truncatus, Ziphius cavirostris

Summary

The marine waters of Dhofar are characterised by dynamic oceanographic conditions strongly influenced by summer and winter monsoons, as well as highly variable bathymetry comprised of continental shelf and steep shelving habitats that plummet to great depths. This provides a range of highly productive habitats for a diverse array of cetacean species. These have been documented during dedicated survey work completed since 1999. The area is extremely important for Arabian Sea humpback whales; data reveal a high degree of site fidelity, as well as behaviours associated with reproduction (singing and calves) and feeding. Seventeen cetacean species have been positively identified in the region thus far, ranging from resident nearshore communities of Indo-Pacific humpback dolphins and Indo-Pacific bottlenose dolphins to deep-diving species such as Risso’s dolphins, rough toothed dolphins and Cuvier’s beaked whales. Recent sightings and acoustic data suggest the area is also likely to be important for Northern Indian Ocean blue whales.

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

The Arabian Sea humpback whale (ASHW) population is the only known population of humpback whales not to undertake long-range migrations between low-latitude breeding grounds and high-latitude feeding grounds (Mikhalev 1997, Minton, Collins, et al. 2011). The population is genetically isolated and distinct (Pomilla, Amaral, et al. 2014), and mark-recapture estimates generated from photo identification studies off the coast of Oman are fewer than 100 individuals (82 individuals 95% CI 60-111), providing the rationale for an IUCN Red list status of Endangered (Minton et al. 2008). Dedicated field surveys, satellite tracking and passive acoustic monitoring have confirmed that the Dhofar area is one of the most important habitats for this population in Oman’s waters. Within the Dhofar area, the highest density of sightings, vocalizations and occupancy (as evidenced by satellite tracks and localized behaviour) is concentrated in the Hallaniyats Bay (Minton et al. 2011; Baldwin et al. 2011; Willson et al. 2012; Willson et al. 2013; Willson et al. 2014; Willson et al. 2015; ESO, 2018; Supreme Council, 2019; Cerchio et al. 2018). Indian Ocean humpback dolphins (Sousa plumbea) are also observed in the Dhofar area and wider Arabian Sea Coast with a strong preference for near-shore shallow coastal habitat. Encounters were made around Hasik Bay and southwest of Salalah (Minton et al. 2011) although sightings have also been documented in intervening areas. The species is listed as Endangered on the IUCN Red List (Braulik et al., 2017).

Criterion B: Distribution and Abundance

Sub-criterion Bii: Aggregations

Modelling of humpback whale sightings data in relation to survey effort using spatial eigenvector filtering to account for spatial autocorrelation, as well as results of satellite telemetry studies, confirm that the higher relative densities of whales in the Dhofar area are a reflection of their behaviour and not only survey effort (Corkeron et al. 2011, Willson et al. 2016, 2017, 2018).  The aggregations have been associated with feeding and breeding behaviour and in one survey period these activities were observed concurrently (Baldwin et al. 2011; Willson et al. 2011).

Criterion C: Key Life Cycle Activities

Sub-criterion Ci: Reproductive Areas

Passive acoustic monitoring has documented the presence of ASHW song between November and the end of May (Cerchio et al. 2016; Cerchio et al. 2018). Further breeding-related behaviour has been observed in the form of competitive groups off Ras Hasik (Baldwin et al. 2011). Mother and calf pairs have been observed in the Dhofar area on 7 occasions between 2000 and 2014 (ESO, 2018).

Sub-criterion Cii: Feeding Areas

Bubble-net feeding by ASHWs has been documented within the Hasik/Hallaniyats Bay (Baldwin et al. 2011) along with 17 other feeding events recorded in the area between 2001 and 2017 (ESO, 2018). Feeding records also exist for other species including Bryde’s whales, false killer whales, common dolphins, both common and Indo-Pacific bottlenose dolphins and Indian Ocean humpback dolphins (ESO, 2018).

Criterion D: Special Attributes

Sub-criterion Dii: Diversity

The diversity in this area includes a range of species exhibiting different ecological preferences, with some species exploiting near shore shallow habitats (e.g. humpback dolphins) and others offshore habitats (e.g. Cuvier’s beaked whales). The range of species also represents species feeding at different trophic levels, from baleen whales to top predators, such as killer whales and false killer whales. Review of sightings data suggests that   Ras Nus marks the westernmost extent of humpback dolphin records with a lack of sightings between this point westwards to Mirbat (ESO, 2018). A minimum of 17 cetacean species have been confirmed to occur in the Dhofar area, and dwarf sperm whales are suspected to occur. The list of confirmed species includes: Common dolphin (Delphinus delphis tropicalis), Common bottlenose dolphin (Tursiops truncatus), spinner dolphin (Stenella longirostris), Indo-Pacific bottlenose dolphin (Tursiops aduncus), rough-toothed dolphin (Steno bredanensis), Indian Ocean humpback dolphin (Sousa plumbea), Risso’s dolphin (Grampus griseus), false killer whale (Pseudorca crassidens), killer whale (Orcinus orca), dwarf sperm whale (Kogia sima), melon-headed whale (Peponocephala electra), short-finned pilot whale (Globicephala macrorhynchus), Cuvier’s beaked whale (Ziphius cavirostris), sperm whale (Physeter macrocephalus), Bryde’s whale (Balaenoptera edeni), humpback whale (Megaptera novaeangliae) and Northern Indian Ocean blue whale (Balaenoptera musculus indica). This diverse assemblage of 18 species has been recorded between ‘Ras Nus’ and Ras Hasik (Minton et al. 2011; Baldwin et al. 2011; Willson et al. 2012; Willson et al. 2013; Willson et al. 2014; Willson et al. 2015; ESO, 2018; Supreme Council, 2019).

Supporting Information

Baldwin, R. M. 2000. Oman’s humpback whales (Megaptera novaeangliae) The Journal of Oman Studies 11 11-18.

Baldwin, R., and R. V. Salm 1994. Whales and Dolphins along the Coast of Oman. Muscat Printing Press, Muscat.

Baldwin, R. M., T. Collins, K. Van Waerebeek, and G. Minton. 2004. The Indo-Pacific humpback dolphin of the Arabian region: A status review. Aquatic Mammals 30:111 – 124.

Baldwin, R. M. 2003. Whales and Dolphins of Arabia. Mazoon Printing Press, Muscat, Oman. 116pp.

Baldwin, R.M., Gallagher, M.D. and Van Waerebeek, K. 1999. A review of cetaceans from waters off the Arabian Peninsula. In: Oman’s Natural History, eds. Fisher, M., Spalton, A. and Gazanfar, S., Backhuys Publishers, Leiden. Pp. 161-189.

Baldwin, R., Collins, T., Minton, G., Willson, A. and Corkeron, P., 2013. Arabian Sea Humpback Whales 2011 Update: resights, bubble feeding and hotspots. Working Paper No. SC/63/SH27). Cambridge, UK: International Whaling Commission.

Baldwin, R. M., Willson, A and Collins, T. 2015. Watching out for whales: industry responsibility to address threats to Arabian Sea humpback whales in the Gulf of Masirah, Oman. Paper submitted to the International Whaling Commission Scientific Committee, IWC San Diego, 19 May – 1st June, 2015. SC/66a/SH23 (Available from IWC Office).

Braulik, G.T., Findlay, K.P., Cerchio, S., Baldwin, R.M. 2017. Assessment of the conservation status of the Indian Ocean Humpback dolphin Sousa plumbea using the IUCN Red List Criteria, in: Humpback Dolphins (Sousa spp.): Current Status and Conservation. Eds T.A. Jefferson, B.E. Curry, Advances in Marine Biology.

Brock, J.C. and McClain, C.R., 1992. Interannual variability in phytoplankton blooms observed in the northwestern Arabian Sea during the southwest monsoon. Journal of Geophysical Research: Oceans, 97(C1), pp.733-750.

Brown, S.G. 1957. Whales observed in the Indian Ocean. Notes on their distribution. Mar. Obs. 27(177): 157–65.

Cerchio S, Willson A, Muirhead C, Al Harthi S, Baldwin R, Bonato M, Collins T, Di Clemente J, Dulau V, Estrade V, et al. (eds). 2018. Geographic variation in song indicates both isolation of Arabian Sea humpback whales and presence of Southern Hemisphere whales off Oman. International Whaling Commission Report No. IWC/SC67B/CMP19. Bled, Slovenia.

Cerchio S, Willson A, Muirhead C, Minton G, Collins T, Baldwin R, Sarrouf Willson M, Al Harthi S. 2016. Preliminary Report on Long-term Detection of Arabian Sea Humpback Whale Vocalizations off Oman. Report number           SC/66b/SH/32 submitted to the Scientific Committee of the International Whaling Commission. Bled.

Cooke, J.G. & Brownell Jr., R.L. 2018. Balaenoptera edeni. The IUCN Red List of Threatened Species 2018: e.T2476A50349178. http://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T2476A50349178.en.

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Environment Society of Oman. 2019. Oman Cetacean Database. OMCD Ver20160527. Data accessed 2019-03-01

Jefferson TA, Curry BE. 2015. Chapter One – Humpback Dolphins: A Brief Introduction to the Genus Sousa. In: Thomas AJ, Barbara EC editors. Advances in Marine Biology: Academic Press. p. 1-16.

Kershaw F., Leslie M.S., Collins T., Mansur R.M., Smith B.D., Minton G., Baldwin R., LeDuc R.G., Anderson R.C., Brownell R.L., Rosenbaum H.C. 2013. Population differentiation of two forms of Bryde’s whales in the Indian and Pacific Oceans. Journal of Heredity doi:10.1093/jhered/est057

Kindle, J.C. and Arnone, R.A., 2001. A review of the surface circulation of the Northern Arabian Sea. In Proc. 1st International Conference on Fisheries, Aquaculture and Environment in the NW Indian Ocean, edited by: Claereboudt, M., Goddard, S., Al-Oufi, H., and MacIlwain, J., Sultan Qaboos University, Muscat, Sultanate of Oman (pp. 113-122).

Mendez, M., Subramanian, A., Collins, T., Minton, G., Baldwin, R., Berggren, P., Särnblad, A., Amir, O.A., Peddemors, V.M., Karczmarski, L., Guissamulo, A., Rosenbaum, H.C., 2011. Molecular ecology meets remote sensing: environmental drivers to population structure of humpback dolphins in the Western Indian Ocean. Heredity, 1-13.

Mikhalev, Y. A. 1996a. Bryde’s whales of the Arabian Sea and adjacent waters. Paper SC/49/O35 presented to the IWC Scientific Committee, June 1996. Pages 1-10.

Mikhalev, Y. A. 1996b. Pygmy blue whales of the Northern-Western Indian Ocean. Document presented to the 48th meeting of the International Whaling Commission SC/48/SH30. Pages 1-30.

Mikhalev, Y. A. 1997. Humpback whales Megaptera novaeangliae in the Arabian Sea. Marine Ecology Progress Series 149:13-21.

Mikhalev, Y. A. 1998. Sperm whales of the Arabian Sea. Paper SC/50/CAWS40 presented to the IWC Scientific Committee, April 1998. Pages 1-7.

Mikhalev, Y. A. 2000. Whaling in the Arabian Sea by the whaling fleets Slava and Sovetskaya Ukraina. In: Tormosov, D.D., Mikhalev, Y.A., Best, P.B., B., Zemsky, V.A., Sekiguchi, K., and Brownell Jr, R.L., editors. Soviet Whaling Data [1949-1979]. Moscow: Center for Russian Environmental Policy, Marine Mammal Council. p 141-181.

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Minton, G., Collins, T. J. Q., Pomilla, C., Findlay, K. P., Rosenbaum, H. C., Baldwin, R., and Brownell Jr, R. L. 2008. Megaptera novaeangliae, Araiban Sea subpopulation. IUCN Red List of Threatened Species http://www.iucnredlist.org/details/132835.

Minton, G., T. J. Q. Collins, K. P. Findlay & R. Baldwin. 2010. Cetacean distribution in the coastal waters of the Sultanate of Oman. Journal of Cetacean Research and Management, 11, 301-313.

Minton. G., Cerchio, S., Collins. T., Ersts. P., Findlay, K.P., Pomilla, C., Bennet, D., Meyer,M.A., Razafindrakoto, Y., Kotze, P.G.H., Ooshuizen, W.H., Lesliem., Andrianarivelo, Baldwin, R., Ponnampalam, L., and Rosenbaum, H.C. 2010. A note on the comparison of humpback whale tail fluke catalogues from the Sultanate of Oman with Madagascar and the East Africa mainland. Journal of Cetacean Research and Management. 11(1):65-68, 2010.

Minton, G., T. J. Q. Collins, K. P. Findlay, P. J. Ersts, H. C. Rosenbaum, P. Berggren & R. M. Baldwin (2011) Seasonal distribution, abundance, habitat use and population identity of humpback whales in Oman. Journal of Cetacean Research and Management, Special Issue on Southern Hemisphere Humpback Whales, 185–198.

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Papastavrou, V. and Van Waerebeek, K., 1997. A note on the occurrence of humpback whales (Megaptera novaeangliae) in tropical and subtropical areas: the upwelling link. Annu. Rep. Int. Whal. Comm, 47, pp.945-947.

Pomilla, C. Amaral, A., Collins, T., Minton, G., Findlay, K., Leslie, M., Ponnampalam, L., Baldwin, R., Rosenbaum, H.  2014. The World’s Most Isolated and Distinct Whale Population? Humpback Whales of the Arabian Sea. PLoS ONE, 9(12), p.e114162. Available at:  http://dx.plos.org/10.1371/journal.pone.0114162

Salm, R. V., R. A. C. Jensen, and V. Papastavrou. 1993. Marine fauna of Oman: Cetaceans, turtles, seabirds and shallow water corals. Pages 1-66. IUCN, Gland, Switzerland.

Sheppard, C. ed., 2018. World Seas: An Environmental Evaluation: Volume II: The Indian Ocean to the Pacific. Academic Press.

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Van Bressem, M.F., Minton, G., Collins, T., Willson, A., Baldwin, R and Van Warebeek, K. 2014. Tattoo-like skin disease in the endangered subpopulation of the Humpback Whale, Megaptera novaeangliae, in Oman (Cetacea: Balaenopteridae). Zoology in the Middle East, 2014. http://dx.doi.org/10.1080/09397140.2014.994316

Willson, A., Baldwin, R., Minton, G. and Collins, T. 2012. Arabian Sea humpback whale research update for 2011/2012. Paper SC/64/SH30 presented to the International Whaling Commission Scientific Committee, Panama June 2012, (available from the IWC Office).

Willson, A., Baldwin, R., Minton, G., Gray, H., Findlay, K., Collins, T.  2013. Arabian Sea humpback whale research update for 2012/13. Paper SC/65a/SH06 presented to the International Whaling Commission Scientific Committee, Jeju, South Korea, June 2013. 08pp, (available from the IWC Office).

Willson, A., Baldwin, R., Cerchio, S., Geyer, Y., Godley B., Gray, H., Al-Harthi, S., Minton, Al-Zehlawi, N., M.Witt., Rosenbaum, H., Zerbini, A. 2014. Preliminary results and first insights from satellite tracking studies of male Arabian Sea humpback whales. Paper SC/65b/SH19 presented to the International Whaling Commission Scientific Committee, Slovenia, May 2014. (Available from the IWC Office).

Willson, A., Baldwin, R., Cerchio, S., Collins, T. Findlay, K., Gray, H., Godley B., Al-Harthi, S., Kennedy, A., Minton, G., Zerbini, A and Witt, M. 2015. Research update of satellite tracking studies of male Arabian Sea humpback whales; Oman. Paper SC/66a/SH22 presented to the International Whaling Commission Scientific Committee, San Diego, May 2015. (Available from the IWC Office).

Willson, A., Baldwin, R., Cerchio, S., Collins, T. Findlay, K., Gray, H., Godley B., Gray, H., Al-Harthi, S., Kennedy, A., Minton, Sucunza, F., Zerbini, A., Witt, M. 2016a. Research update on satellite tagging studies of the Arabian Sea humpback whale in the Sultanate of Oman. Paper SC/66b/SH28 presented to the International Whaling Commission Scientific Committee, Slovenia, June 2016. (Available from the IWC Office).

Willson, A., Kowalik, J., Godley, J., Baldwin, R., Struck, A., Struck, L., Nawaz, R. and Witt, M. 2016b. Priorities for addressing whale and ship strike co-occurence off the coast of Oman and the wider North Indian Ocean. Paper SC/66b/HIM/10 presented to the International Whaling Commission Scientific Committee, Slovenia, June 2016. Available from the IWC Office).

Willson, A., Baldwin, R., Collins, T., Godley, B., Minton, G., Al Harthi, S., Pikesley, S., Witt. 2017. Preliminary ensemble ecological niche modelling of Arabian Sea humpback whale vessel sightings and satellite telemetry data. Paper presented to the International Whaling Commission Scientific Committee, Slovenia, May 2017. (Available from the IWC)

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