Daniel L. Webster

Killer Whales in Hawaiian Waters: Information on Population Identity and Feeding Habits

ABSTRACT Killer whales (Orcinus orca) have only infrequently been reported from Hawaiian waters, and most of what is known about killer whales worldwide comes from studies in coastal temperate waters. Here we present 21 records of killer whales from within the Hawaiian Exclusive Economic Zone between 1994 and 2004. Killer whales were recorded nine months of the year, most around the main Hawaiian Islands. Although there were more records than expected during the period when humpback whales are abundant around the Islands, there is likely an increase in sighting effort during that period. Killer whales were documented feeding on both a humpback whale and cephalopods, and two species of small cetaceans were observed fleeing from killer whales. Although it is possible that there are both marine mammal–eating and cephalopod-eating populations within Hawaiian waters, it seems more likely that Hawaiian killer whales may not exhibit foraging specializations as documented for coastal temperate populations. Saddle patch pigmentation patterns were generally fainter and narrower than those seen in killer whales from the temperate coastal North Pacific. Analysis of skin samples from two animals indicated two mitochondrial haplotypes, one identical to the “Gulf of Alaska transient 2” haplotype (a mammal-eating form), and the other a new haplotype one base different from haplotypes found for mammal-eating killer whales in coastal Alaskan waters.

Nuclear and Mitochondrial Patterns of Population Structure in North Pacific False Killer Whales (Pseudorca crassidens)

False killer whales (Pseudorca crassidens) are large delphinids typically found in deep water far offshore. However, in the Hawaiian Archipelago, there are 2 resident island-associated populations of false killer whales, one in the waters around the main Hawaiian Islands (MHI) and one in the waters around the Northwestern Hawaiian Islands (NWHI). We use mitochondrial DNA (mtDNA) control region sequences and genotypes from 16 nuclear DNA (nucDNA) microsatellite loci from 206 individuals to examine levels of differentiation among the 2 island-associated populations and offshore animals from the central and eastern North Pacific. Both mtDNA and nucDNA exhibit highly significant differentiation between populations, confirming limited gene flow in both sexes. The mtDNA haplotypes exhibit a strong pattern of phylogeographic concordance, with island-associated populations sharing 3 closely related haplotypes not found elsewhere in the Pacific. However, nucDNA data suggest that NWHI animals are at least as differentiated from MHI animals as they are from offshore animals. The patterns of differentiation revealed by the 2 marker types suggest that the island-associated false killer whale populations likely share a common colonization history, but have limited contemporary gene flow.

High levels of persistent organic pollutants measured in blubber of island-associated false killer whales (Pseudorca crassidens) around the main Hawaiian Islands

Abstract : Persistent organic pollutants (POPs) have been measured in tissues of marine mammals since the mid 1960s (Holden and Marsden, 1967; Wolman and Wilson, 1970). These compounds include several pesticides (e.g., DDTs, chlordanes) and industrial chemicals (e.g., PCBs) that are ubiquitous, highly lipophilic and not readily degraded or metabolized. As a result, they can biomagnify to high levels in lipid- rich tissues of top-level marine predators. POPs enter marine waters via direct inputs (e.g., sewage outfalls, industrial and agricultural runoff) as well as from indirect sources (e.g., ocean currents) (Friedlander et al., 2005). Exposure to POPs in marine mammals has been linked to a number of biological effects including reproductive impairment (DeLong et al., 1973; Subramanian et al., 1987), reduced reproductive success (Wells et al., 2005), immune suppression (De Swart et al., 1994; Hammond et al., 2005; Ross et al., 1995) and endocrine disruption (reviewed in O Hara and O Shea (2001)). Although many POPs, such as PCBs and DDTs, have been banned for production or use in the US for more than thirty years, some of these compounds are still used in other regions of the world (Fielder, 2008; van den Berk, 2009) and continue to be measured in the tissues of marine mammals throughout coastal regions of the US.

Characterizing a Foraging Hotspot for Short-Finned Pilot Whales and Blainville's Beaked Whales Located off the West Side of Hawai'i Island by Using Tagging and Oceanographic Data.

Satellite tagging data for short-finned pilot whales (Globicephala macrorhynchus) and Blainville’s beaked whales (Mesoplodon densirostris) were used to identify core insular foraging regions off the Kona (west) Coast of Hawai‘i Island. Ship-based active acoustic surveys and oceanographic model output were used in generalized additive models (GAMs) and mixed models to characterize the oceanography of these regions and to examine relationships between whale density and the environment. The regions of highest density for pilot whales and Blainville’s beaked whales were located between the 1000 and 2500 m isobaths and the 250 and 2000 m isobaths, respectively. Both species were associated with slope waters, but given the topography of the area, the horizontal distribution of beaked whales was narrower and located in shallower waters than that of pilot whales. The key oceanographic parameters characterizing the foraging regions were bathymetry, temperature at depth, and a high density of midwater micronekton scattering at 70 kHz in 400–650 m depths that likely represent the island-associated deep mesopelagic boundary community and serve as prey for the prey of the whales. Thus, our results suggest that off the Kona Coast, and potentially around other main Hawaiian Islands, the deep mesopelagic boundary community is key to a food web that supports insular cetacean populations.

Short Note: Open-Ocean Movements of a Satellite-Tagged Blainville’s Beaked Whale (Mesoplodon densirostris): Evidence for an Offshore Population in Hawai‘i?

Abstract : In Hawaiian waters, a single stock of Blainville s beaked whale (Mesoplodon densirostris) is recognized, extending throughout the U.S. Exclusive Economic Zone (EEZ) surrounding the archipelago and into adjacent international waters (Carretta et al., 2011). Abundance within the entire EEZ around Hawai i was estimated at 2,872 individuals based on a large vessel sighting survey (Barlow, 2006), with a single on-effort sighting near the western boundary of the EEZ (Hamilton et al., 2009). There is, however, considerable uncertainty associated with this estimate (CV = 1.17; Barlow, 2006), and there is recent evidence that individuals documented around the main Hawaiian Islands may not be part of an open-ocean population (McSweeney et al., 2007; Schorr et al., 2009). Individual Blainville s beaked whales instrumented with satellite tags off the island of Hawai i have remained strongly associated with the island, primarily using slope habitats for the entire duration of satellite tag transmissions (up to 71 d; Schorr et al., 2009). Schorr et al. (2009) noted a mean distance from shore of 16.9 km (range 4.4 to 27.7 km) and a mean depth of 1,156 m (range 880 to 1,455 m) for six satellite tagged individuals, over periods ranging from 15 to 71 d (median = 43 d), with from 26 to 405 locations per individual (median = 195 locations/ individual). Although these individuals moved a cumulative distance of at least 8,000 km over the duration of their tag attachments, median distances of locations from the tagging location for the different individuals ranged from 19.9 to 91.8 km, and the maximum distance any individual moved from where it was tagged was only 139 km (Schorr et al., 2009). Combined with long-term resightings of distinctive individuals off the island (McSweeney et al., 2007), such results suggest the existence of an island-resident population.

Swim Speed and Acceleration Measurements of Short-Finned Pilot Whales (Globicephala macrorhynchus) in Hawai'i

Cascadia Research Collective, 218 1/2 W. 4th Avenue, Olympia, WA 98501, USAOver the last few years, studies of top predators inmarine ecosystems have benefited from the use of bio-logging systems (Naito 2004; Rutz and Hays 2009). Forexample, researchers use these techniques to study ani-mal foraging tactics and diving physiology by analyzingacceleration (body angle and stroke), and parameterssuch as swim depth and swim speeds (e.g., Sato et al.2003, 2007; Sakamoto et al. 2009).Short-finned pilot whale (Globicephala macrorhynchus),a top predator, is found worldwide in tropical and warmtemperate waters. Mature males are from 4.5 to 7 m inlength and mature females are from 3.5 to 5 m in length(Bernard and Reilly 1999). Previous studies suggestedthey are foraging during deep dives which cannot beobserved visually. Their primary prey are squid and inHawai‘i they are known to make deep dives (600–800 m)during the day, but also spend considerable periods oftime shallow diving or surface resting during the day(Baird et al. 2003). Amano and Baird (1998) recordeddeep dives over 100 m off Japan. Soto et al. (2008)recorded sound, depth, and orientation from triaxialaccelerometers and magnetometers, and suggested preychasing behavior by analyzing vertical speed and soundemission during deep dives. For a better understandingof foraging tactics and diving physiology of this species,for example studying prey pursuit in a horizontal direc-tion, stroking patterns and body angle, or assessingbehavior by acceleration, we need to record accelerationand swim speed simultaneously. However, swim speedfor short-finned pilot whales has not yet been recorded.We used remotely deployed suction-cup tags formeasuring swim speed and acceleration of short-finnedpilot whales. The understanding of toothed whale be-havior has been advanced by using suction-cup attacheddata loggers (for a review see Hooker and Baird 2001).There are several types of suction-cup attached tag: oneattached with multiple suction-cups that fixed a datalogger in place (e.g., Soto et al. 2008), which with asingle suction-cup connected to a data logger with aflexible plastic tube (Baird et al. 2005), and one with asingle suction-cup that fixed a data logger in place.With removely-deployed tags, it is difficult to set thetag parallel to the water flow. Therefore it would behard to record swim speed using a propeller with amultiple suction-cup tag. A tag using a flexible plastictube cannot record acceleration caused by the animalprecisely because it is not fixed on the animal’s body.A tag fixed on a suction-cup has been demonstratedto record swim speed and acceleration simultaneouslyin previous studies (finless porpoises, Neophocaenaphocaenoides, Akamatsu et al. 2005; sperm whales,Physeter macrocephalus, Aoki 2008). The purpose ofour work was to determine whether this type of suction-cup tag is appropriate for studying swim speed andacceleration in short-finned pilot whales, and whetherit was possible to determine behavior types based onthe data collected.

A preliminary study of the movement patterns of false killer whales (Pseudorca crassidens) in coastal and pelagic waters of the Northern Territory, Australia

The false killer whale (Pseudorca crassidens) is regarded as Data Deficient globally and in Australia. In most parts of its range, there is little information on its social behaviour, dispersal or ecology. The present study is the first assessment of its movement patterns in Australian waters, on the basis of satellite tracking of four individuals, in the Arafura and Timor Seas from late March to early July 2014. When initially tagged, the four individuals occurred in a single group; they then showed generally similar movement patterns and regularly re-associated. Total distance travelled by tagged individuals ranged from 5161km (over a 54-day period) to 7577km (104 days). Distance from land varied from 100m to 188km (median distance 24km). Individual minimum convex polygons covered an area of 72368 to 86252km2, with a total overlap of 64038km2. Water depths varied from 0.3 to 118m (median 36m). In total, 15% of records were in waters shallower than 10m, and 26% of records were within 10km of land. The present study indicated that false killer whales appear to regularly use coastal and pelagic waters in this region and, hence, should be afforded more conservation attention.

5. Biologically Important Areas for Cetaceans Within U.S. Waters – Hawai‘i Region

Of the 18 species of odontocetes known to be present in Hawaiian waters, small resident populations of 11 species—dwarf sperm whales, Blainville’s beaked whales, Cuvier’s beaked whales, pygmy killer whales, short-finned pilot whales, melonheaded whales, false killer whales, pantropical spotted dolphins, spinner dolphins, rough-toothed dolphins, and common bottlenose dolphins—have been identified, based on two or more lines of evidence, including results from small-boat sightings and survey effort, photo-identification, genetic analyses, and satellite tagging. In this review, we merge existing published and unpublished information along with expert judgment for the Hawai‘i region of the U.S. Exclusive Economic Zone and territorial waters in order to identify and support the delineation of 20 Biologically Important Areas (BIAs) for these small and resident populations, and one reproductive area for humpback whales. The geographic extent of the BIAs in Hawaiian waters ranged from approximately 700 to 23,500 km. BIA designation enhances existing information already available to scientists, managers, policymakers, and the public. They are intended to provide synthesized information in a transparent format that can be readily used toward analyses and planning under U.S. statutes that require the characterization and minimization of impacts of anthropogenic activities on marine mammals. Odontocete BIAs in Hawai‘i are biased toward the main Hawaiian Islands and populations off the island of Hawai‘i, reflecting a much greater level of research effort and thus certainty regarding the existence and range of small resident populations off that island. Emerging evidence of similar small resident populations off other island areas in Hawaiian waters suggest that further BIA designations may be necessary as more detailed information becomes available.

Familial social structure and socially driven genetic differentiation in Hawaiian short-finned pilot whales

Social structure can have a significant impact on divergence and evolution within species, especially in the marine environment, which has few environmental boundaries to dispersal. On the other hand, genetic structure can affect social structure in many species, through an individual preference towards associating with relatives. One social species, the short‐finned pilot whale (Globicephala macrorhynchus), has been shown to live in stable social groups for periods of at least a decade. Using mitochondrial control sequences from 242 individuals and single nucleotide polymorphisms from 106 individuals, we examine population structure among geographic and social groups of short‐finned pilot whales in the Hawaiian Islands, and test for links between social and genetic structure. Our results show that there are at least two geographic populations in the Hawaiian Islands: a Main Hawaiian Islands (MHI) population and a Northwestern Hawaiian Islands/Pelagic population (FST and ΦST p < .001), as well as an eastern MHI community and a western MHI community (FST p = .009). We find genetically driven social structure, or high relatedness among social units and clusters (p < .001), and a positive relationship between relatedness and association between individuals (p < .0001). Further, socially organized clusters are genetically distinct, indicating that social structure drives genetic divergence within the population, likely through restricted mate selection (FST p = .05). This genetic divergence among social groups can make the species less resilient to anthropogenic or ecological disturbance. Conservation of this species therefore depends on understanding links among social structure, genetic structure and ecological variability within the species.