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Sally Mizroch

National Marine Fisheries Service, Alaska Fisheries Science Center, Marine biologist

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Worked at the AFSC in Seattle 1977-2016, Blue Sea Research since 2016. Humpback whale photo-ID matching and database. Comprehensive papers on vital rates, distribution and movements of large whales using both whaling and photo-ID data.

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Robert Leo Brownell Jr

Alexander Burdin

James Gilpatrick

NOAA/NMFS Alaska Fisheries Science Center

Alexandre Zerbini

University of California, San Diego

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Papers by Sally Mizroch

Distribution and movements of fin whales in the North Pacific Ocean

Mammal Review, 2009

1. We summarize fin whale Balaenoptera physalus catch statistics, sighting data, mark recoveries ... more 1. We summarize fin whale Balaenoptera physalus catch statistics, sighting data, mark recoveries and acoustics data. The annual cycle of most populations of fin whales had been thought to entail regular migrations between high-latitude summer feeding grounds and lower-latitude winter grounds. Here we present evidence of more complex and varied movement patterns. 2. During summer, fin whales range from the Chukchi Sea south to 35°N on the Sanriku coast of Honshu, to the Subarctic Boundary (ca. 42°N) in the western and central Pacific, and to 32°N off the coast of California. Catches show concentrations in seven areas which we refer to as 'grounds', representing productive feeding areas. 3. During winter months, whales have been documented over a wide area from 60°N south to 23°N. Coastal whalers took them regularly in all winter months around Korea and Japan and they have been seen regularly in winter off southern California and northern Baja California. There are also numerous fin whale sightings and acoustic detections north of 40°N during winter months. Calves are born during the winter, but there is little evidence for distinct calving areas. 4. Whales implanted with Discovery-type marks were killed in whaling operations, and location data from 198 marked whales demonstrate local site fidelity, consistent movements within and between the main summer grounds and long migrations from low-latitude winter grounds to high-latitude summer grounds. 5. The distributional data agree with immunogenetic and marking findings which suggest that the migratory population segregates into at least two demes with separate winter mating grounds: a western ground off the coast of Asia and an eastern one off the American coast. Members of the two demes probably mingle in the Bering Sea/Aleutian Islands area. 6. Prior research had suggested that there were at least two non-migratory stocks of fin whale: one in the East China Sea and another in the Gulf of California. There is equivocal evidence for the existence of additional non-migratory groups in the Sanriku-Hokkaido area off Japan and possibly the northern Sea of Japan, but this is based on small sample sizes.

Visual observations of sei and other whale abundance from research vessel Yushin-Maru No.3 in the North Pacific Ocean from 2011-07-11 to 2011-09-08 (NCEI Accession 0224257)

This dataset contains visual observations of sei and other whale abundance from research vessel Y... more This dataset contains visual observations of sei and other whale abundance from research vessel Yushin-Maru No.3 in the North Pacific Ocean. It provides information for the proposed future in-depth assessment of sei and other whales in terms of both abundance and stock structure. This MSR RATS cruise U2011-005. These data are part of the World Data Services for Oceanography. Cruise report is in PDF.

Visual sightings of blue, sei, fin whales from the research vessel Yushin-Maru No.3 in the North Pacific Ocean from 2012-07-13 to 2012-09-10 (NCEI Accession 0224175)

This dataset contains visual sightings of blue, sei, fin whales from the research vessel Yushin-M... more This dataset contains visual sightings of blue, sei, fin whales from the research vessel Yushin-Maru No.3 in the North Pacific Ocean. It provides information for the proposed future in-depth assessment of sei and other whales in terms of both abundance and stock structure. This is MSR RATS cruise U2012-001. These data are part of the World Data Services for Oceanography. Cruise report is in PDF.

Data from: Long-term isolation at a low effective population size greatly reduced genetic diversity in Gulf of California fin whales

The Gulf of California, Mexico is home to many cetacean species, including a presumed resident po... more The Gulf of California, Mexico is home to many cetacean species, including a presumed resident population of fin whales, Balaenoptera physalus. Past studies reported very low levels of genetic diversity among Gulf of California fin whales and a significant level of genetic differentiation from con-specifics in the eastern North Pacific. The aim of the present study was to assess the degree and timing of the isolation of Gulf of California fin whales in a population genetic analysis of 18 nuclear microsatellite genotypes from 402 samples and 565 mitochondrial control region DNA sequences (including mitochondrial sequences retrieved from NCBI). The analyses revealed that the Gulf of California fin whale population was founded ~2.3 thousand years ago and has since remained at a low effective population size (~360) and isolated from the eastern North Pacific (Nem between 0.89–1.4). The low effective population size and high degree of isolation implied that Gulf of California fin whales ...

Progress in Oceanography

sperm, minke and bowhead whales) was in decline in the Bering Sea in the 1960s and early 1970s; a... more

In Memoriam – Dale W. Rice

Aquatic Mammals, 2018

How vulnerable is the Sea of Cortez fin whale population

Previous genetic analyses have demonstrated that the fin whales in the Sea of Cortez likely are g... more Previous genetic analyses have demonstrated that the fin whales in the Sea of Cortez likely are genetically (and presumably demographically) isolated from North Pacific fin whales. Consequently the Sea of Cortez fin whale population is likely more vulnerable to anthropogenic effects and habitat changes. Here we extend previous work by genetic analyses of microsatellite and mtDNA nucleotide sequences in 375 and 24 fin whale samples from the Sea of Cortez and North Pacific, respectively. We will estimate long- and short-term effective population sizes in these two populations and compare the estimates with data from the much larger North Atlantic fin whale population(s). The objective of the analysis is to assess how vulnerable the Sea of Cortez fin whale population is to random genetic effects, such as loss of adaptive potential and inbreeding.

Alaska marine mammal stock assessments, 2020

The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical M... more The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center.

Alaska marine mammal stock assessments, 2015

NOTE – NMFS is in the process of reviewing humpback whale stock structure under the Marine Mammal... more NOTE – NMFS is in the process of reviewing humpback whale stock structure under the Marine Mammal Protection Act (MMPA) in light of the 14 Distinct Population Segments established under the Endangered Species Act (ESA) (81 FR 62259, 8 September 2016). A complete revision of the humpback whale stock assessments will be postponed until this review is complete. In the interim, new information on humpback whale mortality and serious injury is provided within this report.

How vulnerable are the fin whales in the Gulf of California

Alaska marine mammal stock assessments, 2016

NOTE – December 2015: In areas outside of Alaska, studies of harbor porpoise distribution have in... more NOTE – December 2015: In areas outside of Alaska, studies of harbor porpoise distribution have indicated that stock structure is likely more fine-scaled than is reflected in the Alaska Stock Assessment Reports. No data are available to define stock structure for harbor porpoise on a finer scale in Alaska. However, based on comparisons with other regions, it is likely that several regional and sub-regional populations exist. Should new information on harbor porpoise stocks become available, the harbor porpoise Stock Assessment Reports will be updated.

Beluga whale, Delphinapterus leucas, satellite-tagging and health assessments in Cook Inlet, Alaska, 1999 to 2002

Cook Inlet beluga whales, Delphinapterus leucas, are currently listed as ‘Endangered’ under the U... more Cook Inlet beluga whales, Delphinapterus leucas, are currently listed as ‘Endangered’ under the U.S. Endangered Species Act (ESA). The National Marine Fisheries Service (NMFS) began monitoring this population during the 1990s after it was added to the ESA Candidate Species list in 1988. Monitoring efforts included aerial surveys, and in 1995, the first attempts to capture and satellite-tag whales. Working with Canadian scientists and Alaska Native subsistence hunters in 1995 and 1997, tagging methods were adapted to conditions in Cook Inlet (muddy water, extreme tides, and extensive mudflats), culminating in successful capture and tracking of a whale during the summer of 1999. This was followed by three more years of capture and tagging studies during late summer. Tags were attached to 18 whales between 1999 and 2002. We do not have detailed accounts of these later tagging seasons (e.g., similar to the Appendix chronicling events from the 1997 and 1999 seasons in Ferrero et al. (200...

Movements and Population Structure of Humpback Whales in the North Pacific

Marine Mammal Science, 2001

Year code reflects 1990-1993 except for some SEAK early winter sightings kept with their respecri... more

Ocean nomads: Distribution and movements of sperm whales in the North Pacific shown by whaling data and Discovery marks

Marine Mammal Science, 2012

We investigated the distribution and movements of sperm whales (Physeter macrocephalus) in the No... more We investigated the distribution and movements of sperm whales (Physeter macrocephalus) in the North Pacific by analyzing whaling data and movement data of whales marked with Discovery marks. Prior studies suggested that there were discrete "stocks" of sperm whales, assuming that the intervals between historical areas of concentration indicated subpopulation boundaries. Our analyses clearly refute this assumption: whaling and marking data suggest no obvious divisions between separate demes or stocks within the North Pacific. Sperm whales appear to be nomadic and show widespread movements between areas of concentration, with documented movements of over 5,000 km, time spans between marking and recovery over 20 yr, and ranges that cover many thousand km 2. Males appear to range more widely than females. Sperm whales likely travel in response to geographical and temporal variations in the abundance of medium-and large-sized pelagic squids, their primary prey. Our analyses demonstrate that males and females concentrated seasonally in the Subtropical Frontal Zone (ca. 28ºN-34ºN) and the Subarctic Frontal Zone (ca. 40ºN-43ºN), and males also concentrated seasonally near the Aleutian Islands and along the Bering Sea shelf edge. It appears that the sperm whales targeted by the pelagic whalers range widely across this ocean basin.

Baleen whales are not important as prey for killer whales Orcinus orca in high-latitude regions

Marine Ecology Progress Series, 2007

Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals... more Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals. However, whether or not baleen whales represent an important prey source for killer whales is debatable. A hypothesis by Springer et al. (2003) suggested that overexploitation of large whales by industrial whaling forced killer whales to prey-switch from baleen whales to pinnipeds and sea otters, resulting in population declines for these smaller marine mammals in the North Pacific and southern Bering Sea. This prey-switching hypothesis is in part contingent upon the idea that killer whales commonly attack mysticetes while they are in these high-latitude areas. In this study, we used photographic and sighting data from long-term studies of baleen whales in 24 regions worldwide to determine the proportion of whales that bear scars (rake marks) from killer whale attacks, and to examine the timing of scar acquisition. The results of this study show that there is considerable geographic variation in the proportion of whales with rake marks, ranging from 0% to > 40% in different regions. In every region, the great majority of the scars seen were present on the whales' bodies when the animals were first sighted. Less than 7% (9 of 132) of scarred humpback whales with multi-year sighting histories acquired new scars after the first sighting. This suggests that most killer whale attacks on baleen whales target young animals, probably calves on their first migration from low-latitude breeding and calving areas to high-latitude feeding grounds. Overall, our results imply that adult baleen whales are not an important prey source for killer whales in high latitudes, and therefore that one of the primary assumptions underlying the Springer et al. (2003) prey-switching hypothesis (and its purported link to industrial whaling) is invalid.

Have North Pacific killer whales switched prey species in response to depletion of the great whale populations?

Marine Ecology Progress Series, 2006

hypothesized that populations of seals, sea lions and sea otters in the northern North Pacific Oc... more hypothesized that populations of seals, sea lions and sea otters in the northern North Pacific Ocean and Bering Sea declined because of increased predation by killer whales, in what they termed a 'sequential megafaunal collapse'. They hypothesized that the killer whales had been dependent on large whales for food, and that their increased predation on the smaller marine mammals was directly due to the depletion of great whale populations as a result of post-World War II industrial whaling. The maps presented by Springer et al. (2003) masked the development and precipitous decline of post-World War II industrial whaling. Our analysis shows that north of 50°N, whaling

Estimation of Fetal Growth and Gestation in Bowhead Whales

Journal of the American Statistical Association, 2001

... C. Shane Reese, James A. Calvin, John C. George, and Raymond J. Tarpley ... James Calvin is P... more

Migratory destinations of humpback whales wintering in the Mexican Pacific

The migratory destinations of humpback whales that winter off the Pacific coast of Mexico were ex... more The migratory destinations of humpback whales that winter off the Pacific coast of Mexico were examined using photo-identification. Fluke photographs taken between 1983 and 1993 from the three main whale aggregations in this area (383 from the Mainland coast; 471 from Baja California Peninsula; and 450 from Revillagigedo Archipelago) were compared with collections from all known summering grounds in the North Pacific (593 off California-Oregon-Washington; 48 off British Columbia; 429 off Southeastern Alaska; 141 off Prince William Sound; and 133 from the western Gulf of Alaska). The migratory movements of these whales were clearly non-random. The results of the photographic comparisons and the statistical tests show clear evidence for preferred migratory destinations of humpback whales from Mainland and Baja California to California-Oregon-Washington and British Columbia summering regions. Nevertheless, differences in whale abundance estimates between these summering and wintering aggregations indicate the presence of some unsampled summering region(s). The principal migratory destination was not detected for the Revillagigedo region, although matches were found with all the summering regions sampled. This supports the hypothesis that the humpback whales from Revillagigedo are separate from the 'American stock'. Based on the known abundance estimates, historical whaling records and genetic structure of the populations, it is proposed that historical feeding grounds off the Aleutian Islands and/or the Bering Sea are the main summer destinations of the whales from Revillagigedo.

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

Journal of Mammalogy, 2004

We used photo-identification records to estimate annual survival of adult humpback whales (Megapt... more We used photo-identification records to estimate annual survival of adult humpback whales (Megaptera novaeangliae) for the central North Pacific stock using models within the software application Program MARK. The analysis is based on 10,567 photographs of 2,400 individual whales taken from 1979 to 1996. The central North Pacific stock winters in Hawai'i and migrates to discrete feeding areas in Alaska for the summer and autumn. The Cormack-Jolly-Seber (CJS) estimate of annual survival based on annual sightings in Hawai'i was 0.963 (95% confidence interval [CI]: 0.944-0.978) and the Pradel estimate was 0.963 (95% CI: 0.944-0.976), with a population rate of increase of 1.10 (95% CI: 1.03-1.16). The best survival estimate for southeastern Alaska whales, based on Barker's model, was 0.957 (95% CI: 0.943-0.967). The best survival estimate for Prince William Sound whales, also based on Barker's model, was 0.984 (95% CI: 0.954-0.995). Whales from the central North Pacific stock mix in Hawai'i; therefore, the best apparent survival estimate for the entire stock is from the pooled Hawai'i data. However, this analysis also demonstrated that we could reduce heterogeneity with Barker's model and obtain more plausible estimates of survival for the whales in discrete feeding areas using semiannual sightings in Hawai'i as opportunistic resightings.

Long-term isolation at a low effective population size greatly reduced genetic diversity in Gulf of California fin whales

Scientific Reports

The Gulf of California, Mexico is home to many cetacean species, including a presumed resident po... more The Gulf of California, Mexico is home to many cetacean species, including a presumed resident population of fin whales, Balaenoptera physalus. Past studies reported very low levels of genetic diversity among Gulf of California fin whales and a significant level of genetic differentiation from con-specifics in the eastern North Pacific. The aim of the present study was to assess the degree and timing of the isolation of Gulf of California fin whales in a population genetic analysis of 18 nuclear microsatellite genotypes from 402 samples and 565 mitochondrial control region DNA sequences (including mitochondrial sequences retrieved from NCBI). The analyses revealed that the Gulf of California fin whale population was founded ~2.3 thousand years ago and has since remained at a low effective population size (~360) and isolated from the eastern North Pacific (N e m between 0.89-1.4). The low effective population size and high degree of isolation implied that Gulf of California fin whales are vulnerable to the negative effects of genetic drift, human-caused mortality and habitat change. Population genetic data hold the potential to provide insights into the basis of genetic variation in natural populations 1 , which in turn is a function of past and present effective population sizes, migration rates, selection, and mutation rates. A population acquires genetic variation by mutation and immigration. Genetic variation is lost by random genetic drift resulting in higher rates of loss in small and isolated populations compared to larger, connected populations 2. Possible consequences of low genetic variation include increased genetic load and loss of adaptive traits, which in turn can elevate short-and long-term extinction rates 3-6. Consequently, understanding the processes that shaped contemporary levels of genetic variation may add vital insights to inform the conservation and management of local populations. Population genetic assessments have proven particularly useful to study elusive species, such as baleen whales 7-10. Baleen whales typically undertake long-range seasonal migrations to forage in cold nutrient-rich waters at high latitudes during the summer and winter in warm tropical waters during the breeding season 11. Exceptions to this pattern are Omura's (Balaenoptera omurai) 12 and Bryde's whales (Balaenoptera brydei) 13 , which remain at low latitudes all-year as well as bowhead whales (Balaena mysticetus) that are confined to polar waters 14. A few populations among those baleen whale species that undertake seasonally migrations, do not migrate but remain in the same area year-round, such as blue whales (Balaenoptera musculus) 15,16 and humpback whales (Megaptera novaeangliae) in the Arabian Sea 17-20. Baleen whales are also observed year-round in the Gulf of California, Mexico. Baleen whales are commonly observed around the Midriff Islands and in the Canal de Ballenas between the east coast of the Baja California Peninsula and Isla Angel de la Guarda 21-23. These whales were probably first noted by, and the canal named by,

Distribution and movements of fin whales in the North Pacific Ocean

Mammal Review, 2009

1. We summarize fin whale Balaenoptera physalus catch statistics, sighting data, mark recoveries ... more 1. We summarize fin whale Balaenoptera physalus catch statistics, sighting data, mark recoveries and acoustics data. The annual cycle of most populations of fin whales had been thought to entail regular migrations between high-latitude summer feeding grounds and lower-latitude winter grounds. Here we present evidence of more complex and varied movement patterns. 2. During summer, fin whales range from the Chukchi Sea south to 35°N on the Sanriku coast of Honshu, to the Subarctic Boundary (ca. 42°N) in the western and central Pacific, and to 32°N off the coast of California. Catches show concentrations in seven areas which we refer to as 'grounds', representing productive feeding areas. 3. During winter months, whales have been documented over a wide area from 60°N south to 23°N. Coastal whalers took them regularly in all winter months around Korea and Japan and they have been seen regularly in winter off southern California and northern Baja California. There are also numerous fin whale sightings and acoustic detections north of 40°N during winter months. Calves are born during the winter, but there is little evidence for distinct calving areas. 4. Whales implanted with Discovery-type marks were killed in whaling operations, and location data from 198 marked whales demonstrate local site fidelity, consistent movements within and between the main summer grounds and long migrations from low-latitude winter grounds to high-latitude summer grounds. 5. The distributional data agree with immunogenetic and marking findings which suggest that the migratory population segregates into at least two demes with separate winter mating grounds: a western ground off the coast of Asia and an eastern one off the American coast. Members of the two demes probably mingle in the Bering Sea/Aleutian Islands area. 6. Prior research had suggested that there were at least two non-migratory stocks of fin whale: one in the East China Sea and another in the Gulf of California. There is equivocal evidence for the existence of additional non-migratory groups in the Sanriku-Hokkaido area off Japan and possibly the northern Sea of Japan, but this is based on small sample sizes.

Visual observations of sei and other whale abundance from research vessel Yushin-Maru No.3 in the North Pacific Ocean from 2011-07-11 to 2011-09-08 (NCEI Accession 0224257)

This dataset contains visual observations of sei and other whale abundance from research vessel Y... more This dataset contains visual observations of sei and other whale abundance from research vessel Yushin-Maru No.3 in the North Pacific Ocean. It provides information for the proposed future in-depth assessment of sei and other whales in terms of both abundance and stock structure. This MSR RATS cruise U2011-005. These data are part of the World Data Services for Oceanography. Cruise report is in PDF.

Visual sightings of blue, sei, fin whales from the research vessel Yushin-Maru No.3 in the North Pacific Ocean from 2012-07-13 to 2012-09-10 (NCEI Accession 0224175)

This dataset contains visual sightings of blue, sei, fin whales from the research vessel Yushin-M... more This dataset contains visual sightings of blue, sei, fin whales from the research vessel Yushin-Maru No.3 in the North Pacific Ocean. It provides information for the proposed future in-depth assessment of sei and other whales in terms of both abundance and stock structure. This is MSR RATS cruise U2012-001. These data are part of the World Data Services for Oceanography. Cruise report is in PDF.

Data from: Long-term isolation at a low effective population size greatly reduced genetic diversity in Gulf of California fin whales

The Gulf of California, Mexico is home to many cetacean species, including a presumed resident po... more The Gulf of California, Mexico is home to many cetacean species, including a presumed resident population of fin whales, Balaenoptera physalus. Past studies reported very low levels of genetic diversity among Gulf of California fin whales and a significant level of genetic differentiation from con-specifics in the eastern North Pacific. The aim of the present study was to assess the degree and timing of the isolation of Gulf of California fin whales in a population genetic analysis of 18 nuclear microsatellite genotypes from 402 samples and 565 mitochondrial control region DNA sequences (including mitochondrial sequences retrieved from NCBI). The analyses revealed that the Gulf of California fin whale population was founded ~2.3 thousand years ago and has since remained at a low effective population size (~360) and isolated from the eastern North Pacific (Nem between 0.89–1.4). The low effective population size and high degree of isolation implied that Gulf of California fin whales ...

Progress in Oceanography

sperm, minke and bowhead whales) was in decline in the Bering Sea in the 1960s and early 1970s; a... more

In Memoriam – Dale W. Rice

Aquatic Mammals, 2018

How vulnerable is the Sea of Cortez fin whale population

Previous genetic analyses have demonstrated that the fin whales in the Sea of Cortez likely are g... more Previous genetic analyses have demonstrated that the fin whales in the Sea of Cortez likely are genetically (and presumably demographically) isolated from North Pacific fin whales. Consequently the Sea of Cortez fin whale population is likely more vulnerable to anthropogenic effects and habitat changes. Here we extend previous work by genetic analyses of microsatellite and mtDNA nucleotide sequences in 375 and 24 fin whale samples from the Sea of Cortez and North Pacific, respectively. We will estimate long- and short-term effective population sizes in these two populations and compare the estimates with data from the much larger North Atlantic fin whale population(s). The objective of the analysis is to assess how vulnerable the Sea of Cortez fin whale population is to random genetic effects, such as loss of adaptive potential and inbreeding.

Alaska marine mammal stock assessments, 2020

The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical M... more The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center.

Alaska marine mammal stock assessments, 2015

NOTE – NMFS is in the process of reviewing humpback whale stock structure under the Marine Mammal... more NOTE – NMFS is in the process of reviewing humpback whale stock structure under the Marine Mammal Protection Act (MMPA) in light of the 14 Distinct Population Segments established under the Endangered Species Act (ESA) (81 FR 62259, 8 September 2016). A complete revision of the humpback whale stock assessments will be postponed until this review is complete. In the interim, new information on humpback whale mortality and serious injury is provided within this report.

How vulnerable are the fin whales in the Gulf of California

Alaska marine mammal stock assessments, 2016

NOTE – December 2015: In areas outside of Alaska, studies of harbor porpoise distribution have in... more NOTE – December 2015: In areas outside of Alaska, studies of harbor porpoise distribution have indicated that stock structure is likely more fine-scaled than is reflected in the Alaska Stock Assessment Reports. No data are available to define stock structure for harbor porpoise on a finer scale in Alaska. However, based on comparisons with other regions, it is likely that several regional and sub-regional populations exist. Should new information on harbor porpoise stocks become available, the harbor porpoise Stock Assessment Reports will be updated.

Beluga whale, Delphinapterus leucas, satellite-tagging and health assessments in Cook Inlet, Alaska, 1999 to 2002

Cook Inlet beluga whales, Delphinapterus leucas, are currently listed as ‘Endangered’ under the U... more Cook Inlet beluga whales, Delphinapterus leucas, are currently listed as ‘Endangered’ under the U.S. Endangered Species Act (ESA). The National Marine Fisheries Service (NMFS) began monitoring this population during the 1990s after it was added to the ESA Candidate Species list in 1988. Monitoring efforts included aerial surveys, and in 1995, the first attempts to capture and satellite-tag whales. Working with Canadian scientists and Alaska Native subsistence hunters in 1995 and 1997, tagging methods were adapted to conditions in Cook Inlet (muddy water, extreme tides, and extensive mudflats), culminating in successful capture and tracking of a whale during the summer of 1999. This was followed by three more years of capture and tagging studies during late summer. Tags were attached to 18 whales between 1999 and 2002. We do not have detailed accounts of these later tagging seasons (e.g., similar to the Appendix chronicling events from the 1997 and 1999 seasons in Ferrero et al. (200...

Movements and Population Structure of Humpback Whales in the North Pacific

Marine Mammal Science, 2001

Year code reflects 1990-1993 except for some SEAK early winter sightings kept with their respecri... more

Ocean nomads: Distribution and movements of sperm whales in the North Pacific shown by whaling data and Discovery marks

Marine Mammal Science, 2012

We investigated the distribution and movements of sperm whales (Physeter macrocephalus) in the No... more We investigated the distribution and movements of sperm whales (Physeter macrocephalus) in the North Pacific by analyzing whaling data and movement data of whales marked with Discovery marks. Prior studies suggested that there were discrete "stocks" of sperm whales, assuming that the intervals between historical areas of concentration indicated subpopulation boundaries. Our analyses clearly refute this assumption: whaling and marking data suggest no obvious divisions between separate demes or stocks within the North Pacific. Sperm whales appear to be nomadic and show widespread movements between areas of concentration, with documented movements of over 5,000 km, time spans between marking and recovery over 20 yr, and ranges that cover many thousand km 2. Males appear to range more widely than females. Sperm whales likely travel in response to geographical and temporal variations in the abundance of medium-and large-sized pelagic squids, their primary prey. Our analyses demonstrate that males and females concentrated seasonally in the Subtropical Frontal Zone (ca. 28ºN-34ºN) and the Subarctic Frontal Zone (ca. 40ºN-43ºN), and males also concentrated seasonally near the Aleutian Islands and along the Bering Sea shelf edge. It appears that the sperm whales targeted by the pelagic whalers range widely across this ocean basin.

Baleen whales are not important as prey for killer whales Orcinus orca in high-latitude regions

Marine Ecology Progress Series, 2007

Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals... more Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals. However, whether or not baleen whales represent an important prey source for killer whales is debatable. A hypothesis by Springer et al. (2003) suggested that overexploitation of large whales by industrial whaling forced killer whales to prey-switch from baleen whales to pinnipeds and sea otters, resulting in population declines for these smaller marine mammals in the North Pacific and southern Bering Sea. This prey-switching hypothesis is in part contingent upon the idea that killer whales commonly attack mysticetes while they are in these high-latitude areas. In this study, we used photographic and sighting data from long-term studies of baleen whales in 24 regions worldwide to determine the proportion of whales that bear scars (rake marks) from killer whale attacks, and to examine the timing of scar acquisition. The results of this study show that there is considerable geographic variation in the proportion of whales with rake marks, ranging from 0% to > 40% in different regions. In every region, the great majority of the scars seen were present on the whales' bodies when the animals were first sighted. Less than 7% (9 of 132) of scarred humpback whales with multi-year sighting histories acquired new scars after the first sighting. This suggests that most killer whale attacks on baleen whales target young animals, probably calves on their first migration from low-latitude breeding and calving areas to high-latitude feeding grounds. Overall, our results imply that adult baleen whales are not an important prey source for killer whales in high latitudes, and therefore that one of the primary assumptions underlying the Springer et al. (2003) prey-switching hypothesis (and its purported link to industrial whaling) is invalid.

Have North Pacific killer whales switched prey species in response to depletion of the great whale populations?

Marine Ecology Progress Series, 2006

hypothesized that populations of seals, sea lions and sea otters in the northern North Pacific Oc... more hypothesized that populations of seals, sea lions and sea otters in the northern North Pacific Ocean and Bering Sea declined because of increased predation by killer whales, in what they termed a 'sequential megafaunal collapse'. They hypothesized that the killer whales had been dependent on large whales for food, and that their increased predation on the smaller marine mammals was directly due to the depletion of great whale populations as a result of post-World War II industrial whaling. The maps presented by Springer et al. (2003) masked the development and precipitous decline of post-World War II industrial whaling. Our analysis shows that north of 50°N, whaling

Estimation of Fetal Growth and Gestation in Bowhead Whales

Journal of the American Statistical Association, 2001

... C. Shane Reese, James A. Calvin, John C. George, and Raymond J. Tarpley ... James Calvin is P... more

Migratory destinations of humpback whales wintering in the Mexican Pacific

The migratory destinations of humpback whales that winter off the Pacific coast of Mexico were ex... more The migratory destinations of humpback whales that winter off the Pacific coast of Mexico were examined using photo-identification. Fluke photographs taken between 1983 and 1993 from the three main whale aggregations in this area (383 from the Mainland coast; 471 from Baja California Peninsula; and 450 from Revillagigedo Archipelago) were compared with collections from all known summering grounds in the North Pacific (593 off California-Oregon-Washington; 48 off British Columbia; 429 off Southeastern Alaska; 141 off Prince William Sound; and 133 from the western Gulf of Alaska). The migratory movements of these whales were clearly non-random. The results of the photographic comparisons and the statistical tests show clear evidence for preferred migratory destinations of humpback whales from Mainland and Baja California to California-Oregon-Washington and British Columbia summering regions. Nevertheless, differences in whale abundance estimates between these summering and wintering aggregations indicate the presence of some unsampled summering region(s). The principal migratory destination was not detected for the Revillagigedo region, although matches were found with all the summering regions sampled. This supports the hypothesis that the humpback whales from Revillagigedo are separate from the 'American stock'. Based on the known abundance estimates, historical whaling records and genetic structure of the populations, it is proposed that historical feeding grounds off the Aleutian Islands and/or the Bering Sea are the main summer destinations of the whales from Revillagigedo.

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

Journal of Mammalogy, 2004

We used photo-identification records to estimate annual survival of adult humpback whales (Megapt... more We used photo-identification records to estimate annual survival of adult humpback whales (Megaptera novaeangliae) for the central North Pacific stock using models within the software application Program MARK. The analysis is based on 10,567 photographs of 2,400 individual whales taken from 1979 to 1996. The central North Pacific stock winters in Hawai'i and migrates to discrete feeding areas in Alaska for the summer and autumn. The Cormack-Jolly-Seber (CJS) estimate of annual survival based on annual sightings in Hawai'i was 0.963 (95% confidence interval [CI]: 0.944-0.978) and the Pradel estimate was 0.963 (95% CI: 0.944-0.976), with a population rate of increase of 1.10 (95% CI: 1.03-1.16). The best survival estimate for southeastern Alaska whales, based on Barker's model, was 0.957 (95% CI: 0.943-0.967). The best survival estimate for Prince William Sound whales, also based on Barker's model, was 0.984 (95% CI: 0.954-0.995). Whales from the central North Pacific stock mix in Hawai'i; therefore, the best apparent survival estimate for the entire stock is from the pooled Hawai'i data. However, this analysis also demonstrated that we could reduce heterogeneity with Barker's model and obtain more plausible estimates of survival for the whales in discrete feeding areas using semiannual sightings in Hawai'i as opportunistic resightings.

Long-term isolation at a low effective population size greatly reduced genetic diversity in Gulf of California fin whales

Scientific Reports

The Gulf of California, Mexico is home to many cetacean species, including a presumed resident po... more The Gulf of California, Mexico is home to many cetacean species, including a presumed resident population of fin whales, Balaenoptera physalus. Past studies reported very low levels of genetic diversity among Gulf of California fin whales and a significant level of genetic differentiation from con-specifics in the eastern North Pacific. The aim of the present study was to assess the degree and timing of the isolation of Gulf of California fin whales in a population genetic analysis of 18 nuclear microsatellite genotypes from 402 samples and 565 mitochondrial control region DNA sequences (including mitochondrial sequences retrieved from NCBI). The analyses revealed that the Gulf of California fin whale population was founded ~2.3 thousand years ago and has since remained at a low effective population size (~360) and isolated from the eastern North Pacific (N e m between 0.89-1.4). The low effective population size and high degree of isolation implied that Gulf of California fin whales are vulnerable to the negative effects of genetic drift, human-caused mortality and habitat change. Population genetic data hold the potential to provide insights into the basis of genetic variation in natural populations 1 , which in turn is a function of past and present effective population sizes, migration rates, selection, and mutation rates. A population acquires genetic variation by mutation and immigration. Genetic variation is lost by random genetic drift resulting in higher rates of loss in small and isolated populations compared to larger, connected populations 2. Possible consequences of low genetic variation include increased genetic load and loss of adaptive traits, which in turn can elevate short-and long-term extinction rates 3-6. Consequently, understanding the processes that shaped contemporary levels of genetic variation may add vital insights to inform the conservation and management of local populations. Population genetic assessments have proven particularly useful to study elusive species, such as baleen whales 7-10. Baleen whales typically undertake long-range seasonal migrations to forage in cold nutrient-rich waters at high latitudes during the summer and winter in warm tropical waters during the breeding season 11. Exceptions to this pattern are Omura's (Balaenoptera omurai) 12 and Bryde's whales (Balaenoptera brydei) 13 , which remain at low latitudes all-year as well as bowhead whales (Balaena mysticetus) that are confined to polar waters 14. A few populations among those baleen whale species that undertake seasonally migrations, do not migrate but remain in the same area year-round, such as blue whales (Balaenoptera musculus) 15,16 and humpback whales (Megaptera novaeangliae) in the Arabian Sea 17-20. Baleen whales are also observed year-round in the Gulf of California, Mexico. Baleen whales are commonly observed around the Midriff Islands and in the Canal de Ballenas between the east coast of the Baja California Peninsula and Isla Angel de la Guarda 21-23. These whales were probably first noted by, and the canal named by,