Hawaiian Cetaceans Outline

 North Pacific Cetaceans - Biogeographic Distributions - Migrations and Breeding Cycle

 Hawaiian Cetaceans

- Seasonal Visitors: Humpback Whale

- Year-around Residents: Melon-headed Whale North Pacific Oceanography

 Water mass: Body of water with a common formation history, which has physical properties distinct from other such water masses. (e.g., Temperature & Salinity)

 Ocean Domains: North Distinct regions of the Pacific ocean, defined using Transition Frontal physical, chemical and Zone biological metrics (e.g., Depth, Thermocline, (Polovina et al. 2011) Seasonality, Productivity) North Pacific Cetacean Distributions

 COSMOPOLITAN  REGIONAL / LOCAL  PANTROPICAL  AMPHITROPICAL  TROPICAL  TROPICAL- TEMPERATE  TEMPERATE

Jefferson, T.A., S. Leatherwood, and M.A. Webber. 1993. FAO species identification guide. Marine mammals of the world. Rome, FAO. 1993.320. p. 587 figs. I. Cosmopolitan Distribution

In theory… a large and contiguous distribution

In practice… its more complicated:

- Different overlapping stocks / species (e.g., Bottlenose dolphin)

- Non-overlapping stocks / species (e.g., Bottlenose dolphin: coastal / pelagic)

Frequently, evidence of disjunct distributions - Biases (low connectivity, low density) - Island-associated stocks

Distribution Patterns: Cosmopolitan

Tursiops truncatus (Bottlenose Dolphin) Distribution Patterns: Regional (Ocean Basin) Tursiops aduncus (Indian Bottlenose Dolphin) Distribution Patterns: Cosmopolitan

Grampus griseus (Risso’s Dolphin)

Distribution Patterns: Local (Disjunct)

Delphinus tropicalis Delphinus capensis (Arabian (Long-beaked Common Dolphin) Common Dolphin) II. Distribution Patterns: Pantropical

Lagenodelphis hosei (Fraser's dolphin) III. Distribution Patterns: Amphitropical

Orcinus orca (Killer Whale)

Distribution Patterns: Amphitropical

Lissodelphis peronii Lissodelphis borealis (So. Right Whale Dolphin) (No. Right Whale Dolphin)

IV. Distribution Patterns: Tropical-Temperate

Delphinus delphis (Common Dolphin)

V. Distribution Patterns: Temperate

Lagenorhynchus obliquidens (Pacific White-sided Dolphin)

Distributions Throughout Breeding Cycle

Physeter catodon (Sperm Whale)

• Length: Males, 50 - 65 ft. Females, 35 - 55 ft. Females: schools ~ 12 adults / calves • Weight: Males: leave "nursery schools" at 4-21 Males, 80,000 lb. years of age and join "bachelor school" Females, 44,000 lb. with other males of similar age / size

Whitehead, H. 2003. Sperm whales: social evolution in the ocean. Chicago, IL: Univ. of Chicago Press Hawaiian Cetacens

Balaenopterid Rorquals

Balaenopterid Rorquals Odontocetes Mysticetes Visiting Cetaceans - Mysticetes

Fin whales observed feeding south of Hawai’i in spring and during winter Other occasional visitors – rorquals: Some researchers suggest - Fin whale (Balaenoptera physalus) that whales migrate into Hawaiian waters primarily in - Minke Whale (Balaenoptera acutorostrata) the autumn and winter

- Sei Whale (Balaenoptera borealis)

- Bryde’s Whale (Balaenoptera edeni) (Mobley et al. 2006) Humpback Whale Distribution

Cosmopolitan distribution

But they have a seasonal changing distribution

Humpback whales born in tropical waters in winter; Megaptera novaeangliae mean = 4.3m long at birth (Big-winged New Englander) Peak birth months: - So hemisphere (August) - No hemisphere (February)

Mating during winter

At winter’s end, calves and mothers migrate to high- latitude feeding grounds

Large-scale Oceanographic Context

Summering Grounds:

- High productivity

Wintering Grounds:

- Warm water - Less predators

Mean Annual Chlorophyll-a concentration from MODIS satellites (2002 – present) Studying Humpback Migrations

Photographs of individually identified humpback whales collected in central and eastern North Pacific during the years 1977 to 1983

Photographs revealed extensive movement between seasonal habitats Whales wintering in Hawaii traveled to feeding regions throughout the coastal waters of Alaska

Whales wintering off Mexico went to Alaskan feeding regions and to the Farallon Islands off central California 2 Winter / 5 Summer Grounds Fidelity to a given feeding region demonstrated by high proportion of return

Fidelity to a given wintering ground less conclusive

Humpbacks in eastern and central North Pacific form a single 'structured stock' consisting of several geographically-isolated 'feeding herds' which intermingle on one or more wintering grounds

(Baker et al. 1986) Humpback Whale Life Cycle

Gestation lasts one year

Calves nurse for 6 – 12 months before becoming independent; at 8-10 m long

At a minimum, they live for 50 years, perhaps up to 90

Data on life expectancy came from animals killed by whaling or stranded

Disagreement regarding age determination method, by examining ear "plug" with annual growth layers (Gabriele et al. 2009) Humpback Whale Breeding Season During winter breeding season, males sing, to attract females and to mediate interactions with other males

Males also engage in aggressive competition for access to mates

Such "competitive groups" feature ramming, tail-slashing and other aggressive behaviors as other males attempt to displace the male closest to the central female Singing During the Breeding Season

Singing is virtually ubiquitous in the species' breeding range in winter

Humpback whale songs consist of several themes sung in the same order, the entire song lasting from a few minutes to half an hour

Singers, who are always male and are usually alone, will sometimes sing continuously for hours or even days

All of the whales in a given population sing the same song. The song changes progressively, yet all singers keep up with the changes

What drives the change in the songs is unknown, but researchers assume sexual selection plays a key role Abundance in the Wintering Grounds

Partenavia Observer (P68)

Aerial surveys from planes Widely distributed across MHI

Need to account for visibility Mostly shelf-slope (e.g., Penguin Banks) (wind) and for group size

Use this information to develop corrected abundance estimates Abundance in the Wintering Grounds

• Significant linear increase (p < 0.05) • Average increase of 7% per year • Reason of 2003 decrease unclear

Humpback Whale Abundance (1993-2003) Mean +/- SD of humpback whale abundance over 11- 6,000 year period 1993 - 2003 5,000

4,000

3,000

2,000

1,000 Corrected Abundance Corrected

- 1993 1995 1998 2000 2003 SPLASH project results (May 2008) Humpback whale population rebounds

A new study shows the number of humpback whales in the Northern Pacific has grown dramatically to more than 18000, a finding likely to spark new debate about the whales' status as an endangered species, according to Hawai'i whale experts SPLASH project results (May 2008)

Connections of wintering / summering grounds – by migrating whales SPLASH project results (May 2008)

Hawaiian whales spend summer from BC to Russia SPLASH project results (May 2008)

Canadian, Alaskan and California-OregonWhales winter in Hawaii Acoustic Monitoring (2008 - 2009) Over past 3 decades, population recovery from whaling-era losses resulted in steady increase in whales wintering in Hawaiian waters and an expansion of their distribution in the MHI

Until recently, no evidence that this expansion included the islands, atolls, and banks of the NWHI (Lammers et al. 2011)

Singing Season: Dates First / Last Recording:

Number days detected in Singing Season (%) Acoustic Monitoring (2008 - 2009)

Songs prevalent at Maro Reef, Lisianski Island, and French Frigate Shoals; also recorded Kure Atoll, Midway Atoll, and Pearl and Hermes Atoll

Timing and abundance of songs followed trends observed on Oahu

Suggests humpbacks use NWHI as wintering area

NWHI could be unknown wintering area (photo-id)

(Lammers et al. 2011) Resident Cetaceans - Odontocetes Melon-headed Whale Distribution

Grow up to 3 meters (9.8 ft) long and weigh over 200 kilograms (440 lb)

The lifespan is at least 20 years and probably up to 30 years

Forms large pods, sometimes up to 1000 strong (Taylor et al. 2008) Resident Melon-Headed Whales

To assess population structure in Hawai‘i, dedicated surveys from 2000 to 2009

Figure 1. Survey effort trackline and sightings of melon-headed whales around the main Hawaiian Islands: 2000–2009.

(Aschettino et al. 2011) Resident Melon-Headed Whales

Using good quality photographs, there were 1,433 unique photo-identified whales

1,046 were distinctive

Of these, 31.5% were seen more than once

(Aschettino et al. 2011) Resident Melon-Headed Whales

Resighting data combined with social network analyses showed evidence of two populations:

- a smaller (400 – 500) resident population, seen exclusively off northwest of the island of Hawai‘i

- a larger population (5000 – 7000), throughout MHI

Resightings of individuals up to 22 yr apart for the Hawai’i-Island resident population and up to 13 yr apart for the MHI population, suggesting long-term residency

(Aschettino et al. 2011) Resident Melon-Headed Whales

Depth of encounters for Hawai’i-Island resident population was significantly shallower (median = 381 m) than those for the MHI population (median = 1,662 m)

Filled triangles show encounter locations with Hawai‘i Island resident population, unfilled triangles show encounter locations with MHI population, and the unfilled diamond represents encounter with group that did not link to either population

(Aschettino et al. 2011) Cetaceans Associated with Eddies Study of the MHI population (n = 10 melon-headed whales)

Tagged off Kona and Kauai in 2008

Tracks in offshore habitat (depth > 3,000 meters)

(Woodworth et al. 2011) Island Lee Eddies – Propagate Westward

friction & eddy decay with time Island

Cyclonic eddies drift northward as they propagate and anticyclonic eddies drift southward as they propagate

Island Lee Eddies – Propagate Westward

Melon-headed whale track, superimposed on satellite altimetry.

Average buoy drifter data shows an average pattern of cyclonic circulation north of 20ºN and anticyclonic circulation south of 20ºN in lee of high Hawaiian Islands

This area corresponds to the general location/paths of mesoscale eddies generated in the lee of the high islands

Whales Associated with Eddy Edges

(Woodworth et al. 2011) References

• Cetacean ranges from: Jefferson, T.A., S. Leatherwood, and M.A. Webber. 1993. FAO species identification guide. Marine mammals of the world. Rome, FAO. 1993.320. p. 587 figs. http://www.cms.int/reports/small_cetaceans/index.htm

• Figures / Images / Reports from Cascadia Research Collective and Marine Mammal Consulting Group References

Baker, C.S., Herman, L. M., Perry, A., Lawton, W.L., Straley, J.M., Wolman, A.A., KaufmanWinn, H.E.,Hall, J.D., Reinke, J.M., Ostman, J. (1986). Migratory movement and population structure of humpback whales (Megaptera novaeangliae) in the central and eastern North Pacific. Marine Ecology Progress Series 423: 261-268.

Lammers, M.O., Fisher-Pool, P.I., Au, W.W.L., Meyer, C.G., Wong, K.B., Brainard, R.E. (2011). Humpback whale Megaptera novaeangliae song reveals wintering activity in the Northwestern Hawaiian Islands. Marine Ecology Progress Series 423: 261-268.

Aschettino, J.M., Baird, R.W., McSweeney, D.J., et al. 2011. Population structure of melon-headed whales (Peponocephala electra) in the Hawaiian Archipelago: Evidence of multiple populations based on photo- identification. Marine Mammal Science. DOI: 10.1111/j.1748- 7692.2011.00517.x

Woodworth PA, Schorr GS, Baird RW, et al. (2011). Eddies as offshore foraging grounds for melon-headed whales. Marine Mammal Science DOI: 10.1111/j.1748-7692.2011.00509.x

Additional References Range and primary habitats of Hawaiian insular false killer whales: informing determination of critical habitat Baird RW, Hanson MB, Schorr GS, Webster DL, McSweeney DJ, Gorgone AM, Mahaffy SD, Holzer DM, Oleson EM, Andrews RD [2012] Endangered Species Research 18(1): 47-61. DOI: 10.3354/esr00435

Temporal patterns in the acoustic signals of beaked whales at Cross Seamount Johnston DW, McDonald M, Polovina J, Domokos R, Wiggins S, Hildebrand J [2008] Biology Letters 4(2): 208-211

Identification of humpback whale Megaptera novaeangliae wintering habitat in the Northwestern Hawaiian Islands using spatial habitat modeling Johnston DW, Chapla ME, Williams LE, Mattila DK [2007] Endangered Species Research 3(3): 249-257