Estimating the Adult Survival Rate of Central North Pacific Humpback Whales (Megaptera Novaeangliae)

Mizroch, Sally A.; Herman, Louis M.; Straley, Janice M.; Glockner-Ferrari, Debbie; Jurasz, Charles M.; Darling, James D.; Cerchio, Salvatore; Gabriele, Christine M.; Salden, Dan R.; Ziegesar, Olga von

doi:10.1644/bos-123

Cited by 62 publications

(66 citation statements)

References 22 publications

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“…The non-calf survival estimate of 0.951 (SE = 0.0135) is similar to markrecapture estimates for non-calf humpback whales Megaptera novaeangliae in the Gulf of Maine (0.951, SE = 0.010 and 0.960, SE = 0.008 ;Buckland 1990 andBarlow &Clapham 1997, respectively), off West Greenland (0.957, SE = 0.028;Larsen & Hammond 2004), and in the central North Pacific (0.963, 95% CI = 0.944 to 0.978; Mizroch et al 2004). Caswell et al (1999) estimated survival of the highly endangered western North Atlantic right whale Eubalaena glacialis population, but these time-varying markrecapture estimates (from about 0.99 to about 0.94) are of crude survival and are not directly comparable to the non-calf survival estimate presented here.…”

Section: Survivalsupporting

confidence: 71%

Survival estimates of western gray whales Eschrichtius robustus incorporating individual heterogeneity and temporary emigration

Bradford¹,

Wade²,

Weller³

et al. 2006

Mar. Ecol. Prog. Ser.

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Gray whales Eschrichtius robustus exist as 2 geographically and genetically distinct populations in the eastern and western North Pacific. Subjected to intensive commercial whaling during the 19th and 20th centuries, the western population presently numbers approximately 100 individuals and is regarded as one of the most endangered baleen whale populations in the world. Since 1997, ongoing studies of western gray whales have resulted in a photographic dataset that can be used for mark-recapture survival estimation. Pollock's robust design was applied to 129 individual whale encounter histories spanning 25 monthly capture occasions from 1997 to 2003. Using Akaike's Information Criterion (AICc) model selection, models incorporating individual heterogeneity in residency patterns and higher temporary emigration probabilities for younger whales provided better fits to the data. Non-calf and calf (1st year post-weaning) survival were estimated as 0.951 (SE = 0.0135, 95% CI = 0.917 to 0.972) and 0.701 (SE = 0.0944, 95% CI = 0.492 to 0.850), respectively, averaging across the best models (n = 13) in order to account for model uncertainty. The non-calf survival point estimate is similar to mark-recapture estimates for Gulf of Maine humpback whales, but lower than an indirect estimate for the eastern gray whale population. Although no statistically robust direct estimates of baleen whale calf survival exist for comparison to the current study, the calf survival estimate is markedly lower than a value suggested for Gulf of Maine humpback whales. Estimation of survival is necessary for assessing the status of western gray whales, which can contribute to increased protection, conservation, and management planning for this critically endangered population.

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Section: Survivalsupporting

confidence: 71%

Survival estimates of western gray whales Eschrichtius robustus incorporating individual heterogeneity and temporary emigration

Bradford¹,

Wade²,

Weller³

et al. 2006

Mar. Ecol. Prog. Ser.

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“…Overall basin-wide estimates of the abundance of humpback whales in the North Pacific were estimated as 6010 (SE = 474) in the early 1990s and appeared to be increasing as they recovered from commercial whaling (Calambokidis et al 1997). Abundance estimates show an increasing trend of about 8% per year for the California-Oregon-Washington feeding aggregation (Calambokidis & Barlow 2004) and 10% per annum for the population that migrates between Hawaii and Alaska (Mizroch et al 2004, Cerchio 1998. We cannot dismiss completely, however, the potential for some effect of predation on the rate of increase; the observed proportion of humpback whale calves in the US West Coast feeding area is lower than other humpback whale populations, although this could be biased by the timing of observations .…”

Section: Discussionmentioning

confidence: 99%

Geographic variation in killer whale attacks on humpback whales in the North Pacific: implications for predation pressure

Steiger¹,

Calambokidis²,

Straley³

et al. 2008

Endang. Species. Res.

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We examined the incidence of rake mark scars from killer whales Orcinus orca on the flukes of humpback whales Megaptera novaeangliae throughout the North Pacific to assess geographic variation in predation pressure. We used 3650 identification photographs from 16 wintering or feeding areas collected during 1990 to 1993 to determine conservative estimates in the percentage of whales with rake mark scarring. Dramatic differences were seen in the incidence of rake marks among regions, with highest rates on wintering grounds off Mexico (26 vs. 14% at others) and feeding areas off California (20 vs. 6% at others), 2 areas between which humpback whales migrate. Although attacks are rarely witnessed, the prevalence of scars demonstrates that a substantial portion of animals are attacked, particularly those that migrate between California and Mexico. Our data also suggest that most attacks occur at or near the wintering grounds in the eastern North Pacific. The prevalence of attacks indicates that killer whale predation has the potential to be a major cause of mortality and a driving force in migratory behavior; however, the location of the attacks is inconsistent with the hypothesis that animals migrate to tropical waters to avoid predation. Our conclusion is that, at least in recent decades, attacks are made primarily on calves at the wintering grounds; this contradicts the hypothesis that killer whales historically preyed heavily on large whales in highlatitude feeding areas in the North Pacific.

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“…In this approach, photographs are taken of distinctive parts of an animal (often the shape of trailing edges and pigmentation of fins) that permit individual identification when observed again. This technique has been used to generate estimates of population size, movement patterns, group structure, and demographic variables such as age at sexual maturity, life span and survival rates for many marine species (Hamilton et al 1998, Chaloupka et al 1999, Forcada et al 1999, Stevick et al 2001, Kendall et al 2003, Mizroch et al 2004, Castro & Rosa 2005. Additionally, data concerning growth rates have also been collected with photo-identification through the use of photo-grammetry (Koski et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Population size and structure of whale sharks Rhincodon typus at Ningaloo Reef, Western Australia

Meekan¹,

Bradshaw²,

Press³

et al. 2006

Mar. Ecol. Prog. Ser.

166

222

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We used photo-identification to produce estimates of population size and structure of whale sharks Rhincodon typus at Ningaloo Reef, Western Australia. We analysed photographs of whale sharks taken from 1992 to 2004. A combination of spot and stripe patterns behind the last gill slit and forward of the dorsal fin (lateral view), and distinctive scars and marks on the body and fins were useful for identifying individual sharks. These patterns appeared to be unique to individuals and distinctive markings could be recognized on some sharks for more than a decade. From 581 photographs, 159 individuals were identified. Of these, 74% were male, 16% were female and 10% were of indeterminate gender. Photographed sharks ranged in estimated size from 3 to 10 m total length (TL). The size distribution of sharks was bimodal with a large peak at 8 m and a smaller peak at 6 m TL. Sixty individuals were resighted during the study. Of these, 46 were resighted at different times during the same year (sometimes on multiple occasions) up to 4 mo after they were initially photographed, and 33 were resighted (4 on > 2 occasions) in different years. The interval between inter-annual resightings was typically 1 to 3 yr; however, 2 sharks were resighted after a period of 12 yr. We estimated the super population of whale sharks that visit Ningaloo Reef to consist of approximately 300 to 500 individuals (95% confidence interval) based on closed population models, or 320 to 440 based on Jolly-Seber open-population models. Our study shows that photo-identification offers a practical, non-invasive and non-destructive means to obtain data on the population size and demography of whale sharks.

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Estimating the Adult Survival Rate of Central North Pacific Humpback Whales (Megaptera Novaeangliae)

Cited by 62 publications

References 22 publications

Survival estimates of western gray whales Eschrichtius robustus incorporating individual heterogeneity and temporary emigration

Survival estimates of western gray whales Eschrichtius robustus incorporating individual heterogeneity and temporary emigration

Geographic variation in killer whale attacks on humpback whales in the North Pacific: implications for predation pressure

Population size and structure of whale sharks Rhincodon typus at Ningaloo Reef, Western Australia

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