Residency and abundance of sperm whales (Physeter macrocephalus) in Nemuro Strait,Hokkaido, Japan

We examined the trend in residence patterns and abundance of male sperm whales in Nemuro Strait, Japan, based on long-term photo-identification (1,513 survey days, total 2,969 photos) between 2006 and 2017. A total of 225 unique individuals were identified during this study, with an average of 36 (SE = 2.55) new individuals identified in each season. The model chosen by maximum likelihood suggests that residence time around Nemuro Strait is 769 (SE = 372.4) days, with individuals staying in the strait about 48 days (SE = 8.36) per year. While the migration patterns of male sperm whales visiting this area are still unclear, these findings along with previous studies suggest that males move from one breeding area to another neighboring area every several weeks, shifting their home ranges gradually over a period of a few years. The abundance of sperm whales in Nemuro Strait varied greatly from year to year; from 28 (95%CI: 24–44) in 2015 and (95%CI: 22–48) in 2016 to 66 (95%CI: 57–84) in 2011. This study provides important knowledge of abundance and residency for Nemuro Strait, information which will contribute to further research on the social structure and movement pattern of male sperm whales.     

Behavioral responses of satellite tracked Blainville's beaked whales (Mesoplodon densirostris) to mid-frequency active sonar

The vulnerability of beaked whales (Family: Ziphiidae) to intense sound exposure has led to interest in their behavioral responses to mid-frequency active sonar (MFAS, 3–8 kHz). Here we present satellite-transmitting tag movement and dive behavior records from Blainville's beaked whales (Mesoplodon densirostris) tagged in advance of naval sonar exercises at the Atlantic Undersea Test and Evaluation Center (AUTEC) in the Bahamas. This represents one of the largest samples of beaked whales individually tracked during sonar operations (n = 7). The majority of individuals (five of seven) were displaced 28–68 km after the onset of sonar exposure and returned to the AUTEC range 2–4 days after exercises ended. Modeled sound pressure received levels were available during the tracking of four individuals and three of those individuals showed declines from initial maxima of 145–172 dB re 1 μPa to maxima of 70–150 dB re 1 μPa following displacements. Dive behavior data from tags showed a continuation of deep diving activity consistent with foraging during MFAS exposure periods, but also suggested reductions in time spent on deep dives during initial exposure periods. These data provide new insights into behavioral responses to MFAS and have important implications for modeling the population consequences of disturbance.     

A citizen science approach to long-term monitoring of humpback whales (Megaptera novaeangliae) off Sydney,Australia

The Cape Solander Whale Migration Study is a citizen science project that annually counts northward migrating humpback whales (Megaptera novaeangliae) off Cape Solander, Sydney, Australia. Dedicated observers have compiled a 20-year data set (1997–2017) of shore-based observations from Cape Solander's high vantage point. Using this long-term data set collected by citizen scientists, we sought to estimate the humpback whale population trend as it continues to recover postexploitation. We estimated an exponential growth rate of 0.099 (95% CI = 0.079–0.119) using a generalized linear model, based on observer effort (number of observation days) and number of whales observed, equating to 10% per annum growth in sightings since 1997. We found that favorable weather conditions for spotting whales off Cape Solander consisted of winds <30 km/hr from a southerly through a north westerly direction. Incidental observations of other cetacean species included the endangered blue whale (Balaenoptera musculus) and data deficient species such as killer whales (Orcinus orca) and false killer whales (Pseudorca crassidens). Citizen science-based studies can provide a cost-effective approach to monitoring wildlife over the time necessary to detect change in a population. Information obtained from citizen science projects like this may help inform policy makers responsible for State and Federal protection of cetaceans in Australian waters and beyond.     

Skin in the game: Epidermal molt as a driver of long-distance migration in whales

Long-distance migration in whales has historically been described as an annual, round-trip movement between high-latitude, summer feeding grounds, and low-latitude, winter breeding areas, but there is no consensus about why whales travel to the tropics to breed. Between January 2009 and February 2016, we satellite-tagged 62 antarctic killer whales (Orcinus orca) of four different ecotypes, of which at least three made short-term (6–8 weeks), long-distance (maximum 11,000 km, round trip), essentially nonstop, migrations to warm waters (SST 20°C–24°C), and back. We previously suggested that antarctic killer whales could conserve body heat in subfreezing (to −1.9°C) waters by reducing blood flow to their skin, but that this might preclude normal (i.e., continuous) epidermal molt, and necessitate periodic trips to warm waters for routine skin maintenance (“skin molt migration,” SMM). In contrast to the century-old “feeding/breeding” migration paradigm, but consistent with a “feeding/molting” hypothesis, the current study provides additional evidence that deferred skin molt could be the main driver of long-distance migration for antarctic killer whales. Furthermore, we argue that for all whales that forage in polar latitudes and migrate to tropical waters, SMM might also allow them to exploit rich prey resources in a physiologically challenging environment and maintain healthy skin.     

Functional and evolutionary analysis of DXL1, a non-essential gene encoding a 1-deoxy-D-xylulose 5-phosphate synthase like protein in Arabidopsis thaliana

The synthesis of 1-deoxy-D-xylulose 5-phosphate (DXP), catalyzed by the enzyme DXP synthase (DXS), represents a key regulatory step of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis. In plants DXS is encoded by small multigene families that can be classified into, at least, three specialized subfamilies. Arabidopsis thaliana contains three genes encoding proteins with similarity to DXS, including the well-known DXS1/CLA1 gene, which clusters within subfamily I. The remaining proteins, initially named DXS2 and DXS3, have not yet been characterized. Here we report the expression and functional analysis of A. thaliana DXS2. Unexpectedly, the expression of DXS2 failed to rescue Escherichia coli and A. thaliana mutants defective in DXS activity. Coherently, we found that DXS activity was negligible in vitro, being renamed as DXL1 following recent nomenclature recommendation. DXL1 is targeted to plastids as DXS1, but shows a distinct expression pattern. The phenotypic analysis of a DXL1 defective mutant revealed that the function of the encoded protein is not essential for growth and development. Evolutionary analyses indicated that DXL1 emerged from DXS1 through a recent duplication apparently specific of the Brassicaceae lineage. Divergent selective constraints would have affected a significant fraction of sites after diversification of the paralogues. Furthermore, amino acids subjected to divergent selection and likely critical for functional divergence through the acquisition of a novel, although not yet known, biochemical function, were identified. Our results provide with the first evidences of functional specialization at both the regulatory and biochemical level within the plant DXS family.     

Stomach contents of long‐finned pilot whales,Globicephala melas,mass‐stranded on Farewell Spit,Golden Bay in 2005 and 2008

Abstract

New data are reported on the diet of the long‐finned pilot whale, Globicephala melas, based on stomach contents recovered from whales involved in a mass stranding on Farewell Spit, Golden Bay, South Island, on 23 January 2008. The stomachs of 11 whales were examined, from which identifiable prey remains were recovered from six, four females and two males (3.1–5.4 m in length). Prey remains comprised exclusively cephalopod beaks (1–46 beaks per whale), attributed to two genera in two orders: arrow squid, Nototodarus spp. (Teuthoidea: Ommastrephidae), and common octopus, Pinnoctopus cordiformis (Octopoda: Octopodidae). The stomachs of eight whales were infested with parasitic nematodes, with two ulcerated; the stomachs of five whales did not contain any prey remains. These data complement and are comparable to the only other information available for this species from this region, reported from whales mass‐stranded at this same location in December 2005. Lower beak rostral length versus mantle length and biomass regression equations for Nototodarus spp. are reviewed, highlighting the importance of the use of species‐specific regression equations for reconstructing both cephalopod mantle length and biomass from lower beak remains in dietary studies.     

Association between pygmy right whales (Caperea marginata) and areas of high marine productivity off Australia and New Zealand

Abstract

Opportunistic sightings and strandings of Caperea marginata (n=196) from the vicinity of Australia and New Zealand (1884 to early 2007) were used to relate geographic and temporal patterns to oceanographic and broad-scale climatic variability. Records were not uniformly distributed along the coast and more (69%) were from Australia than New Zealand. Seven coastal whale ‘hotspots’ were identified which accounted for 61% of records with locality data. Half of the hotspot records were from southeast (37) and northwest (20) Tasmania—others each had 9–15 events. Upwelling and/or high zooplankton abundance has been documented near all whale hotspots. Records of C. marginata occurred in all months, with 75% in spring and summer. Inter-annual variability showed broad agreement between increased whale records (usually in spring/summer) and strongly positive ‘Niño 3.4’ during 1980–1995 but not thereafter. Coastal upwelling and productivity increase during climatic phenomena such as El Niño and are likely to be quickly beneficial to plankton-feeding whales such as C. marginata.     

First report on the stomach contents of long‐finned pilot whales,Globicephala melas,stranded in New Zealand

Abstract

Stomach contents of the long‐finned pilot whale, Globicephala melas, are reported for the first time from New Zealand waters. Analyses based on two male and three female whales (2.5–5.3 m in length) that stranded on Farewell Spit, Golden Bay, South Island in December 2005 revealed a diet comprised exclusively of cephalopods (2-33 lower cephalopod beaks per stomach). Two genera of cephalopod from two orders; arrow squid, Nototodarus spp. (Teuthoidea: Ommastrephidae), and common octopus, Pinnoctopus cordiformis (Octopoda: Octopodidae) were represented. A further five pilot whale stomachs were examined and found to be empty.