Janice Straley is Associate Professor Marine Biology

Recent Submissions

  • Pregnancy rate and reproductive hormones in humpback whale blubber: Dominant form of progesterone differs during pregnancy

    Atkinson, S.; Branch, T. A.; Pack, A. A.; Straley, Janice; Moran, J. R.; Gabriele, C.; Mashburn, K. L.; Cates, K.; Yin, S. (Elsevier, 2023-01-01)
    To better understand reproductive physiology of humpback whales Megaptera novaeangliae that reside in Hawai’i and Alaska, enzyme immunoassays were validated for both progesterone and testosterone in free-ranging and stranded animals (n = 185 biopsies). Concentrations were analyzed between different depths of large segments of blubber taken from skin to muscle layers of stranded female (n = 2, 1 pregnant, 1 non-pregnant) and male (n = 1) whales. Additionally, progesterone metabolites were identified between pregnant (n = 1) and non-pregnant (n = 3) females using high pressure liquid chromatography (HPLC). Progesterone concentrations were compared between juvenile (i.e., sexually immature), lactating, and pregnant females, and male whales, and pregnancy rates of sexually mature females were calculated. Based on replicate samples from ship struck animals collected at 7 depth locations, blubber containing the highest concentration of progesterone was located 1 cm below the skin for females, and the highest concentration of testosterone was in the skin layer of one male whale. HPLC of blubber samples of pregnant and non-pregnant females contain different immunoreactive progesterone metabolites, with the non-pregnant female eluate comprised of a more polar, and possibly conjugated, form of progesterone than the pregnant female. In females, concentrations of progesterone were highest in the blubber of pregnant (n = 28, 28.6 ± 6.9 ng/g), followed by lactating (n = 16, 0.9 ± 0.1 ng/g), and female juvenile (n = 5, 1.0 ± 0.2 ng/g) whales. Progesterone concentrations in male (n = 24, 0.6 ng/g ± 0.1 ng/g) tissues were the lowest all groups, and not different from lactating or juvenile females. Estimated summer season pregnancy rate among sexually mature females from the Hawai’i stock of humpback whales was 0.562 (95 % confidence interval 0.528–0.605). For lactating females, the year-round pregnancy rate was 0.243 (0.09–0.59), and varies depending on the threshold of progesterone assumed for pregnancy in the range between 3.1 and 28.5 ng/g. Our results demonstrate the synergistic value added when combining immunoreactive assays, HPLC, and long-term sighting histories to further knowledge of humpback whale reproductive physiology.
  • Engaging northern rural and Indigenous students: Case studies using One Health principles of educational resilience

    Cotter, Paul; Gildehaus, Lori; Chenoweth, Ellen; Straley, Janice; Hueffer, Karsten; Reynolds, Arleigh J. (University of Aberdeen, 2023)
    Indigenous and rural populations are underrepresented in many science-related educational fields, leading to underrepresentation in biomedical, science, and related professions. A contributing factor is the misalignment of Western education and engagement strategies and these cultures; this is especially true for northern subsistence cultures. We review the influence of a combined One Health/Quadripartite Model of Educational Resilience approach in promoting interest in, recruiting for, and retaining students in biomedical research and community health across three education levels. We suggest a One Health context resonates with Indigenous and rural populations and may be more culturally aligned than conventional education approaches. Implementing Quadripartite Model elements promotes educational accessibility and attractiveness to these populations across our programs. We suggest that 1) disciplines that may be perceived as remote and inaccessible to these populations can be culturally contextualized through a One Health lens and; 2) a more equitable sharing of responsibility for educational success may benefit students from underrepresented populations. Applying One Health/Quadripartite Model approaches may help increase representation of Indigenous and rural populations in a wide range of STEM, biomedical, and community health disciplines. We support continued efforts to modify conventional educational structures, institutions, and strategies to further engage these communities.
  • Bellwethers of change: population modelling of North Pacific humpback whales from 2002 through 2021 reveals shift from recovery to climate response

    Cheeseman, Ted; Barlow, Jay; Acebes, Jo Marie; Audley, Katherina; Bejder, Lars; Birdsall, Catlin; Bracamontes, O. S.; Bradford, Amanda L.; Byington, Josie; Calambokidis, John; et al. (The Royal Society, 2024-02-28)
    For the 40 years after the end of commercial whaling in 1976, humpback whale populations in the North Pacific Ocean exhibited a prolonged period of recovery. Using mark–recapture methods on the largest individual photo-identification dataset ever assembled for a cetacean, we estimated annual ocean-basin-wide abundance for the species from 2002 through 2021. Trends in annual estimates describe strong post-whaling era population recovery from 16 875 (± 5955) in 2002 to a peak abundance estimate of 33 488 (± 4455) in 2012. An apparent 20% decline from 2012 to 2021, 33 488 (± 4455) to 26 662 (± 4192), suggests the population abruptly reached carrying capacity due to loss of prey resources. This was particularly evident for humpback whales wintering in Hawai‘i, where, by 2021, estimated abundance had declined by 34% from a peak in 2013, down to abundance levels previously seen in 2006, and contrasted to an absence of decline in Mainland Mexico breeding humpbacks. The strongest marine heatwave recorded globally to date during the 2014–2016 period appeared to have altered the course of species recovery, with enduring effects. Extending this time series will allow humpback whales to serve as an indicator species for the ecosystem in the face of a changing climate.
  • Rapid range expansion of a marine ectotherm reveals the demographic and ecological consequences of short-term variability in seawater temperature and dissolved oxygen

    Buford, Benjamin P.; Wild, Lauren A.; Schwarz, Richard; Chenoweth, Ellen M.; Sreenivasan, Ashwin; Elahi, Robin; Carey, Nicholas; Hoving, Henk-Jan T.; Straley, Janice; Denny, Mark W. (University of Chicago Press, 2022-04)
    The distributions of marine ectotherms are governed by physiological sensitivities to long-term trends in seawater temperature and dissolved oxygen. Short-term variability in these parameters has the potential to facilitate rapid range expansions, and the resulting ecological and socioeconomic consequences may portend those of future marine communities. Here, we combine physiological experiments with ecological and demographic surveys to assess the causes and consequences of sudden but temporary poleward range expansions of a marine ectotherm with considerable life history plasticity (California market squid, Doryteuthis opalescens). We show that sequential factors related to resource accessibility in the core range—the buildup of large populations as a result of competitive release and climate-associated temperature increase and oxygen loss that constrain aerobic activity—may drive these expansions. We also reveal that poleward range expansion alters the body size—and therefore trophic role—of invading populations, with potential negative implications for socioeconomically valuable resident species. To help forecast rapid range expansions of marine ectotherms, we advocate that research efforts focus on factors impacting resource accessibility in core ranges. Determining how environmental conditions in receiving ecosystems affect body size and how body size is related to trophic role will help refine estimates of the impacts of future marine communities.
  • Biologically important areas II for cetaceans within U.S. and adjacent waters - Gulf of Alaska Region

    Wild, Lauren A.; Riley, Heather; Pearson, Heidi C.; Gabriele, Christine M.; Neilson, Janet L.; Szabo, Andy; Moran, John; Straley, Janice M.; DeLand, Sarah (Frontiers Media S. A., 2023-05-05)
    We delineated and scored Biologically Important Areas (BIAs) for cetacean species in the Gulf of Alaska region. BIAs represent areas and times in which cetaceans are known to concentrate for activities related to reproduction, feeding, and migration, and also the known ranges of small and resident populations. This National Oceanic and Atmospheric Association (NOAA)-led effort uses structured expert elicitation principles to build upon the first version of NOAA’s BIAs for cetaceans. Supporting evidence for these BIAs came from aerial-, land-, and vessel-based surveys; satellite-tagging data; passive acoustic monitoring; Indigenous knowledge; photo-identification data; and/or prey studies. A total of 20 BIAs were identified, delineated, and scored for six species: beluga whale (Delphinapterus leucas), fin whale (Balaenoptera physalus), gray whale (Eschrichtius robustus), humpback whale (Megaptera novaeangliae), North Pacific right whale (Eubalaena japonica), and sperm whale (Physeter macrocephalus). Of the 20 total BIAs, there were two small and resident populations, one migratory, and 17 feeding areas; no reproductive BIAs were identified. An additional five watch list areas were identified, a new feature to the second version of BIAs. In addition to more comprehensive narratives and maps, the BIA II products improve upon the first version by creating metadata tables and incorporating a scoring and labeling system which improves quantification and standardization of BIAs within and across regions. BIAs are compilations of the best available science and have no inherent regulatory authority. They have been used by NOAA, other federal agencies, and the public to support planning and marine mammal impact assessments, and to inform the development of conservation measures for cetaceans.
  • A collaborative and near-comprehensive North Pacific humpback whale photo-ID dataset

    Cheeseman, T.; Southerland, Ken; Acebes, Jo Marie; Audley, Katherina; Barlow, Jay; Bejder, Lars; Birdsall, Caitlin; Bradford, Amanda L.; Byington, Josie K.; Calambokidis, John; et al. (Springer Nature Limited, 2023-06-23)
    We present an ocean‑basin‑scale dataset that includes tail fluke photographic identification (photo‑ID) and encounter data for most living individual humpback whales (Megaptera novaeangliae) in the North Pacific Ocean. The dataset was built through a broad collaboration combining 39 separate curated photo‑ID catalogs, supplemented with community science data. Data from throughout the North Pacific were aggregated into 13 regions, including six breeding regions, six feeding regions, and one migratory corridor. All images were compared with minimal pre‑processing using a recently developed image recognition algorithm based on machine learning through artificial intelligence; this system is capable of rapidly detecting matches between individuals with an estimated 97–99% accuracy. For the 2001–2021 study period, a total of 27,956 unique individuals were documented in 157,350 encounters. Each individual was encountered, on average, in 5.6 sampling periods (i.e., breeding and feeding seasons), with an annual average of 87% of whales encountered in more than one season. The combined dataset and image recognition tool represents a living and accessible resource for collaborative, basin‑wide studies of a keystone marine mammal in a time of rapid ecological change.
  • mtDNA heteroplasmy gives rise to a new maternal lineage in North Pacific humpback whales

    Pierszalowski, Sophie P.; Steel, Debbie J.; Gabriele, Christine M.; Neilson, Janet L.; Vanselow, Phoebe B. S.; Cedarleaf, Jennifer A.; Straley, Janice M.; Baker, C. Scott (Oxford University Press, 2022)
    Heteroplasmy in the mitochondrial genome offers a rare opportunity to track the evolution of a newly arising maternal lineage in populations of non-model species. Here, we identified a previously unreported mitochondrial DNA haplotype while assembling an integrated database of DNA profiles and photo-identification records from humpback whales in southeastern Alaska (SEAK). The haplotype, referred to as A8, was shared by only two individuals, a mature female with her female calf, and differed by only a single base pair from a common haplotype in the North Pacific, referred to as A-. To investigate the origins of the A8 haplotype, we reviewed n = 1,089 electropherograms (including replicate samples) of n = 710 individuals with A- haplotypes from an existing collection. From this review, we found 20 individuals with clear evidence of heteroplasmy for A-/A8 (parental/derived) haplotypes. Of these, 15 were encountered in SEAK, four were encountered on the Hawaiian breeding ground (the primary migratory destination for whales in SEAK) and one was encountered in the northern Gulf of Alaska. We used genotype exclusion and likelihood to identify one of the heteroplasmic females as the likely mother of the A8 cow and grandmother of the A8 calf, establishing the inheritance and germ-line fixation of the new haplotype from the parental heteroplasmy. The mutation leading to this heteroplasmy and the fixation of the A8 haplotype provide an opportunity to document the population dynamics and regional fidelity of a newly arising maternal lineage in a population recovering from exploitation.
  • Sharp decline in humpback whale (Megaptera novaeangliae) survival and reproductive success in southeastern Alaska during and after the 2014–2016 Northeast Pacifc marine heatwave

    Gabriele, Christine M.; Amundson, Courtney L.; Nielson, Janet L.; Straley, Janice M.; Baker, C. Scott; Danielson, Seth Lombard (Springer, 2022-03-10)
    Understanding the ecosystem efects of ocean warming is increasingly important as marine heatwaves become more common and increase in severity. Here, we used Glacier Bay National Park long-term monitoring data (1985–2020) to investigate a sudden, sharp decline in humpback whale reproductive success and survival following the onset of the 2014–2016 Northeast Pacifc marine heatwave (PMH). Oceanographic data confrm a persistent warm-water anomaly in 2015–2016 in Glacier Bay, months later than the PMH was documented in the North Pacifc. We assessed changes in demographic parameters pre- and post-PMH using whale and calf counts and multi-state closed population capture–recapture models. Non-calf abundance decreased by 56% between 2013 and 2018, followed by increases in 2019–2020. The predicted proportion of females in the population declined in 2015–2017 (0.40–0.44). For 5 years during and after the heatwave (2015–2019) calf production was far lower than historic levels (0.041 calves per adult female, in contrast to 0.27 pre-PMH). Calf survival dropped tenfold beginning with calves born in 2013 (0.396–0.032) and midsummer calf losses occurred at an unprecedented rate starting in 2014. Non-calf survival declined from 0.982 pre-PMH to 0.899 post-PMH, lower than any value reported for this species. We surmise that documented changes to the forage fsh and zooplankton prey base during and after the PMH were the main driver of reduced humpback whale survival and reproductive success. Humpback whale abundance and productivity in southeastern Alaska will likely take years to recover from the PMH, assuming a return to favorable feeding conditions. Our work highlights this population’s continued vulnerability as the climate warms into previously unobserved states.
  • Scaling of maneuvering performance in baleen whales: larger whales outperform expectations

    Segre, Paolo S.; Gough, William T.; Roualdes, Edward A.; Cade, David E.; Czapanskiy, Max F.; Fahlbusch, James; Kahane-Rapport, Shirel R.; Oestreich, William K.; Bejder, Lars; Bierlich, K.C.; et al. (Journal of Experimental Biology, 2022-03)
    Despite their enormous size, whales make their living as voracious predators. To catch their much smaller, more maneuverable prey, they have developed several unique locomotor strategies that require high energetic input, high mechanical power output and a surprising degree of agility. To better understand how body size affects maneuverability at the largest scale, we used bio-logging data, aerial photogrammetry and a high-throughput approach to quantify the maneuvering performance of seven species of free-swimming baleen whale. We found that as body size increases, absolute maneuvering performance decreases: larger whales use lower accelerations and perform slower pitch-changes, rolls and turns than smaller species. We also found that baleen whales exhibit positive allometry of maneuvering performance: relative to their body size, larger whales use higher accelerations, and perform faster pitch-changes, rolls and certain types of turns than smaller species. However, not all maneuvers were impacted by body size in the same way, and we found that larger whales behaviorally adjust for their decreased agility by using turns that they can perform more effectively. The positive allometry of maneuvering performance suggests that large whales have compensated for their increased body size by evolving more effective control surfaces and by preferentially selecting maneuvers that play to their strengths.
  • Seasonal Characteristics of Humpback Whales {Megaptera novaeangliae) in Southeastern Alaska

    Straley, Janice M.; Gabriele, Christine M.; Baker, C. Scott (National Park Service Alaska System Support Office, 1995-11)
    Humpback whales were studied in southeastern Alaska to assess seasonal distribution and numbers, migration patterns, length of stay, female reproductive histories, and calf survival. A mean annual estimate and 95% confidence interval of whales present in the study areas was 404 ± 54 individuals. The longest length of stay was nearly 7 months, and the shortest transit to the Hawaiian mating and calving grounds was 39 days. Generally, birth intervals did not vary from one calf every two or three years; individual variation ranged from one to five years. There were few resightings of whales first seen as calves. The recovery of North Pacific humpback whales will only occur through an increase in the survival of calves to become sexually mature and reproducing adults.
  • New views of humpback whale flow dynamics and oral morphology during prey engulfment

    Kosma, Madison, M.; Chenoweth, Ellen M.; Straley, Janice M.; Werth, Alexander J. (Marine Mammal Science, 2019-05-14)
    The rise of inexpensive, user-friendly cameras and editing software promises to revolutionize data collection with minimal disturbance to marine mammals. Video sequences recorded by aerial drones and GoPro cameras provided close-up views and unique perspectives of humpback whales engulfing juvenile salmon at or just below the water surface in Southeast Alaska and Prince William Sound. Although humpback feeding is famous for its flexibility, several stereotyped events were noted in the 47 lunges we analyzed. Engulfment was extremely rapid (mean 2.07 s), and the entrance through which the tongue inverts into the ventral pouch was seen as water rushes in. Cranial elevation was a major contributor to gape, and pouch contraction sometimes began before full gape closure, with reverberating waves indicating rebounding flow of water within the expanded pouch. Expulsion of filtered water began with a small splash at the anterior of the mouth, followed by sustained excurrent flow in the mouth’s central or posterior regions. Apart from a splash of rebounding water, water within the mouth was surprisingly turbulence-free during engulfment, but submersion of the whale’s head created visible surface whirlpools and vortices which may aggregate prey for subsequent engulfment.
  • Exploring variability in the diet of depredating sperm whales in the Gulf of Alaska through stable isotope analysis

    Wild, Lauren A.; Mueter, Franz; Witteveen, Briana H.; Straley, Janice M. (The Royal Society Publishing, 2020-01-27)
    Sperm whales interact with commercially important groundfish fisheries offshore in the Gulf of Alaska (GOA). This study aims to use stable isotope analysis to better understand the trophic variability of sperm whales and their potential prey, and to use dietary mixing models to estimate the importance of prey species to sperm whale diets. We analysed tissue samples from sperm whales and seven potential prey (five groundfish and two squid species). Samples were analysed for stable carbon and nitrogen isotope ratios, and diet composition was estimated using Bayesian isotopic mixing models. Mixing model results suggest that an isotopically combined sablefish/ dogfish group, skates and rockfish make up the largest proportion of sperm whale diets (35%, 28% and 12%) in the GOA. The top prey items of whales that interact more frequently with fishing vessels consisted of skates (49%) and the sablefish/dogfish group (24%). This is the first known study to provide an isotopic baseline of adult male sperm whales and these adult groundfish and offshore squid species, and to assign contributions of prey to whale diets in the GOA. This study provides information to commercial fishermen and fisheries managers to better understand trophic connections of important commercial species.
  • Humpback whales feed on hatchery-released juvenile salmon

    Chenoweth, Ellen M.; Straley, Janice M.; McPhee, Megan V.; Atkinson, Shannon; Reifenstuhl, Steve (The Royal Society Publishing, 2017-06-07)
    Humpback whales are remarkable for the behavioural plasticity of their feeding tactics and the diversity of their diets. Within the last decade at hatchery release sites in Southeast Alaska, humpback whales have begun exploiting juvenile salmon, a previously undocumented prey. The anthropogenic source of these salmon and their important contribution to local fisheries makes the emergence of humpback whale predation a concern for the Southeast Alaska economy. Here, we describe the frequency of observing humpback whales, examine the role of temporal and spatial variables affecting the probability of sighting humpback whales and describe prey capture behaviours at five hatchery release sites. We coordinated twice daily 15 min observations during the spring release seasons 2010–2015. Using logistic regression, we determined that the probability of occurrence of humpback whales increased after releases began and decreased after releases concluded. The probability of whale occurrence varied among release sites but did not increase significantly over the 6 year study period. Whales were reported to be feeding on juvenile chum, Chinook and coho salmon, with photographic and video records of whales feeding on coho salmon. The ability to adapt to new prey sources may be key to sustaining their population in a changing ocean.
  • Pectoral herding: an innovative tactic for humpback whale foraging

    Kosma, Madison, M.; Werth, Alexander J.; Szabo, Andrew R.; Straley, Janice M. (The Royal Society, 2019-09-23)
    Humpback whales (Megaptera novaeangliae) have exceptionally long pectorals (i.e. flippers) that aid in shallow water navigation, rapid acceleration and increased manoeuvrability. The use of pectorals to herd or manipulate prey has been hypothesized since the 1930s. We combined new technology and a unique viewing platform to document the additional use of pectorals to aggregate prey during foraging events. Here, we provide a description of ‘pectoral herding’ and explore the conditions that may promote this innovative foraging behaviour. Specifically, we analysed aerial videos and photographic sequences to assess the function of pectorals during feeding events near salmon hatchery release sites in Southeast Alaska (2016–2018). We observed the use of solo bubble-nets to initially corral prey, followed by calculated movements to establish a secondary boundary with the pectorals—further condensing prey and increasing foraging efficiency. We found three ways in which humpback whales use pectorals to herd prey: (i) create a physical barrier to prevent evasion, (ii) cause water motion to guide prey towards the mouth, and (iii) position the ventral side to reflect light and alter prey movement. Our findings suggest that behavioural plasticity may aid foraging in changing environments and shifts in prey availability. Further study would clarify if ‘pectoral herding’ is used as a principal foraging tool by the broader humpback whale population and the conditions that promote its use.
  • Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation

    Wild, Lauren; Straley, Janice M.; Barnes, Dustin; Bayless, Ali; O'Connell, Victoria; Oleson, Erin; Sarkar, Jit; Behnken, Linda; Falvey, Dan; Martin, Sean; et al. (Acoustical Society of America, 2016-11-22)
    False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal’s range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4–8 kHz) were estimated to be between 115 and 130 dB re 1 lPa2/Hz @ 1 m. Echolocation click source levels over 17–32 kHz bandwidth reached 205 dB re 1lPa @ 1 m pk-pk, or 190 dB re 1lPa @ 1 m (root-meansquare). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.
  • Summary of Reported Whale-Vessel Collisions in Alaskan Waters

    Neilson, Janet L.; Gabriele, Christine M.; Jensen, Aleria S.; Jackson, Kaili; Straley, Janice M. (Hindawi Publishing Corporation, 2012-03-26)
    Here we summarize 108 reported whale-vessel collisions in Alaska from 1978–2011, of which 25 are known to have resulted in the whale's death. We found 89 definite and 19 possible/probable strikes based on standard criteria we created for this study. Most strikes involved humpback whales (86%) with six other species documented. Small vessel strikes were most common (<15 m, 60%), but medium (15–79 m, 27%) and large (≥80 m, 13%) vessels also struck whales. Among the 25 mortalities, vessel length was known in seven cases (190–294 m) and vessel speed was known in three cases (12–19 kn). In 36 cases, human injury or property damage resulted from the collision, and at least 15 people were thrown into the water. In 15 cases humpback whales struck anchored or drifting vessels, suggesting the whales did not detect the vessels. Documenting collisions in Alaska will remain challenging due to remoteness and resource limitations. For a better understanding of the factors contributing to lethal collisions, we recommend (1) systematic documentation of collisions, including vessel size and speed; (2) greater efforts to necropsy stranded whales; (3) using experienced teams focused on determining cause of death; (4) using standard criteria for validating collision reports, such as those presented in this paper.
  • Seasonal presence and potential influence of humpback whales on wintering Pacific herring populations in the Gulf of Alaska

    Straley, Janice M.; Moran, John M.; Boswell, Kevin M.; Vollenweider, Johanna J.; Heintz, Ron A.; Quinn II, Terrance J.; Witteveen, Brianna Harmony; Rice, Stanley D.; Moran, J. R. (2018-01)
    This study addressed the lack of recovery of Pacific herring (Clupea pallasii) in Prince William Sound, Alaska, in relation to humpback whale (Megaptera novaeangliae) predation. As humpback whales rebound from commercial whaling, their ability to influence their prey through top-down forcing increases. We compared the potential influence of foraging humpback whales on three herring populations in the coastal Gulf of Alaska: Prince William Sound, Lynn Canal, and Sitka Sound (133–147°W; 57–61°N) from 2007 to 2009. Information on whale distribution, abundance, diet and the availability of herring as potential prey were used to correlate populations of overwintering herring and humpback whales. In Prince William Sound, the presence of whales coincided with the peak of herring abundance, allowing whales to maximize the consumption of overwintering herring prior to their southern migration. In Lynn Canal and Sitka Sound peak attendance of whales occurred earlier, in the fall, before the herring had completely moved into the areas, hence, there was less opportunity for predation to influence herring populations. North Pacific humpback whales in the Gulf of Alaska may be experiencing nutritional stress from reaching or exceeding carrying capacity, or oceanic conditions may have changed sufficiently to alter the prey base. Intraspecific competition for food may make it harder for humpback whales to meet their annual energetic needs. To meet their energetic demands whales may need to lengthen their time feeding in the northern latitudes or by skipping the annual migration altogether. If humpback whales extended their time feeding in Alaskan waters during the winter months, the result would likely be an increase in herring predation
  • Using movements, genetics and trophic ecology to differentiate inshore from offshore aggregations of humpback whales in the Gulf of Alaska

    Witteveen, Briana Harmony; Straley, Janice M.; Chenoweth, Ellen M.; Baker, C. Scott; Barlow, Jay; Matkin, Craig O.; Gabriele, Christine M.; Neilson, Janet L.; Steel, Debbie J.; von Ziegesar, Olga; et al. (Inter-Research Science Publisher, 2011-09-23)
    Humpback whales Megaptera novaeangliae have been studied in the coastal waters of the Gulf of Alaska (GOA) since the late 1960s, but information about whales foraging offshore is limited. A large-scale collaborative project (SPLASH) provided opportunities to study humpback whales in both inshore and offshore habitats. Using identification photographs and biopsy samples, we explored individual movements, the distribution of mitochondrial (mtDNA) haplotypes, and trophic levels for humpback whales within 3 regions (Kodiak, KOD; Prince William Sound, PWS; and southeastern Alaska, SEAK) of the GOA to determine whether inshore and offshore aggregations of humpback whales are distinct. Each region was divided into inshore and offshore habitats, creating 6 subregions for comparison. Results documenting 2136 individual whales showed that movement within the study area was most frequent between inshore and offshore subregions within a region. In general, movement between regions was minimal. Tissue samples of 483 humpback whales included 15 mtDNA haplotypes. Pairwise chi-squared tests showed haplotype differences between subregions, but inshore PWS was the only subregion with a haplotype composition significantly different than all other subregions. Trophic levels, as inferred from stable nitrogen isotope ratios, were significantly different among subregions, ranging from 3.4 to 4.5. Pairwise comparisons showed that inshore PWS was again the only subregion that significantly differed from all others. Results suggest that the combined inshore and offshore habitats for KOD and the inshore and offshore habitats for SEAK should each be considered as single regional feeding aggregations, while inshore PWS may represent a separate aggregation from PWS offshore.
  • Depredating sperm whales in the Gulf of Alaska: local habitat use and long distance movements across putative population boundaries

    Straley, Janice M.; Schorr, G. S.; Thode, A. M.; Calambokidis, J.; Lunsford, C. R.; Chenoweth, Ellen M.; O'Connell, V. M.; Andrews, R. D. (Inter-Research Science Publisher, 2014-05-08)
    Satellite tags were attached to 10 sperm whales Physeter macrocephalus (1 whale was tagged in 2 different years) to determine the movements of sperm whales involved in removal of sablefish from longline fishing gear in the Gulf of Alaska (GOA). Tags transmitted from 3 to 34 d (median = 22) in 2007 and 7 to 158 d (median = 45) in 2009. Seven whales stayed in the GOA; all were associating with fishing vessels along the slope. Two whales headed south in June shortly after being tagged; one reached the inner third of the Sea of Cortez; the other’s last location was offshore Mexico at 14°N. A third whale stayed in the GOA until October and then headed south, reaching central Baja, Mexico, 158 d after tagging. The whales that travelled to lower latitudes followed no pattern in timing of departure, and at least 2 had different destinations. All whales passed through the California Current without stopping and did not travel to Hawaii; both are areas with known concentrations of sperm whales. Whales travelled faster when south of 56°N than when foraging in the GOA (median rate of median horizontal movement = 5.4 [range: 4.1 to 5.5] and 1.3 [range: 0.6 to 2.5] km h−1, respectively). Tagged sperm whales primarily travelled over the slope, but one spent considerable time over the ocean basin. Information on the timing and movement patterns of sperm whales may provide a means for fishermen to avoid fishing at whale hot spots, potentially reducing interactions between whales and fishermen.
  • Local recruitment of humpback whales in Glacier Bay and Icy Strait, Alaska, over 30 years

    Pierszalowski, Sophie P.; Gabriele, Christine M.; Steel, Debbie J.; Neilson, Janet L.; Vanselow, Phoebe B. S.; Cedarleaf, Jennifer A.; Straley, Janice M.; Baker, C. Scott (2016-03-15)
    We provide new information on the scale at which fidelity and recruitment underlie observed increases in humpback whale Megaptera novaeangliae populations. We used photoidentification records and DNA profiles from whales in Glacier Bay and Icy Strait (GBIS), southeastern Alaska (SEAK) to investigate 3 sources of population increase over 33 yr (1973−2005): local GBIS recruitment, recruitment from elsewhere in SEAK, and immigration from outside SEAK. We defined 2 temporal strata for these longitudinal records: ‘founder’ individuals identified from 1973 to 1985 (n = 74; n = 46 with DNA profiles) and ‘contemporary’ individuals identified from 2004 to 2005 (n = 171; n = 118 with DNA profiles). To distinguish between local recruitment and recruitment from elsewhere in SEAK, we estimated the proportion of the contemporary stratum that was either a returning founder or descended from a founder female. After excluding 42 contemporary whales without a known mother or genotype to infer maternity, 73.6% of the contemporary stratum was confirmed or inferred through parentage analysis to be either a returning founder or a descendant of a founder mother. Of the 25 females with genotypes in the founder stratum, 24 (96%) were either represented in the contemporary stratum, had at least 1 descendant in the contemporary stratum, or both. We found no significant differences in microsatellite allele or mtDNA frequencies between the strata, suggesting little or no immigration from other feeding grounds. Our results highlight the importance of local habitat protection for a recovering species with culturally inherited migratory destinations.

View more