A Norwegian Penthrite Granade for Minke Whales: Hunting Trials with Prototypes and Results from the Hunt in 1984,1985 and 1986

A penthrite grenade to replace cold harpoons in the Norwegian minke whale hunt was developed in 1983–1985. Data on survival times for 259 minke whales were collected from the trials in the 1984–86 hunting seasons, when 3 different prototypes were used. About 45% of the whales were killed instantaneously. The median survival time was 72 s. A substantially higher percentage of instantaneous deaths was recorded for penthrite grenades than for cold harpoons. The criteria for death were cessation of flipper movement, relaxation of the mandible, or sinking without any active movement. Some animals dived before the criteria could be controlled. If the central nervous system, heart, lungs or main vessels were damaged, a high percentage of the animals died instantaneously. In most cases, hits and detonations outside the thorax and central nervous system resulted in longer survival times than hits in the thorax. Survival time increased with whale size and range for animals not killed instantaneously. Marksmanship, technical and functional reliability of equipment and hunting techniques were all crucial to a good result. Better training of gunners, improved weapons and hunting equipment and more rapid reshooting of wounded animals would reduce the proportion of long survival times.     

High Velocity Projectiles for Killing Whales. Hunting Trials using 20 mm High Velocity Projectiles for Minke Whales in 1982

Norway was requested by the International Whaling Commission (IWC) to explore the use of high-velocity projectiles to replace cold harpoon as killing device for minke whales (Anon 1980). Tests of suitable high-velocity projectiles for minke whales were therefore initiated in 1982 as part of a wider project with the purpose of studying alternative killing methods to the traditional cold harpoon used in the Norwegian minke whale hunt until 1984 (Øen 1995). The results of the trials have previously been presented in unpublished reports to the IWC (Øen 1982, 1983, 1992).     

Comparative studies on lipid analysis and ultrastructure in porcine and southern minke whale (Balaenoptera bonaerensis) oocytes

The present study was conducted to clarify the difference in the color of the cytoplasm in immature follicular oocytes from prepubertal and adult minke whales. The four lipid contents (triglyceride, total cholesterol, phospholipids and non-esterified fatty acids) in vitrified immature oocytes from prepubertal and adult minke whales, and also in fresh and vitrified immature porcine oocytes, were measured. The lipid contents in vitrified-warmed minke whale oocytes were similarly high compared with those in vitrified-warmed porcine oocytes. In particular, the total cholesterol and phospholipid contents in the vitrified immature oocytes from prepubertal and adult minke whales were significantly (P<0.05) higher than those from prepubertal pigs. Furthermore, the distribution of lipid droplets in fresh and vitrified immature oocytes was observed in transmission electron microscopy. Lipid droplets in the prepubertal minke whale oocytes were distributed throughout the cytoplasm. In contrast, adult minke whales had larger lipid droplets which were distributed mainly in the central portion of the cytoplasm. The lipid droplets of immature oocytes from prepubertal pigs were larger than those in minke whale oocytes. These results indicated that the difference in the distribution of the cytoplasmic lipid droplets may result in the difference in the color tone of both prepubertal and adult whale oocyte cytoplasm.     

Attempt at intracytoplasmic sperm injection of in vitro matured oocytes in common minke whales (Balaenoptera acutorostrata) captured during the Kushiro Coast Survey

The present study was conducted during the Kushiro Coast Survey in an attempt to produce common minke whale embryos. In Experiment 1, we attempted to determine the appropriate culture duration (30 or 40 h) for in vitro maturation (IVM) of immature oocytes using the Well of the Well method. In Experiment 2, and intracytoplasmic sperm injection (ICSI) was applied to matured oocytes from prepubertal and adult common minke whales after IVM culture (40 or 48 h), and then their embryonic development was assessed. In Experiment 1, the maturation rate of oocytes cultured for 40 h (30.4%) was significantly higher than that of oocytes cultured for 30 h (6.8%; P<0.01). In Experiment 2, a total of 35 and 46 immature oocytes derived from adult (n=2) and prepubertal (n=6) minke whales, respectively, were cultured for 40 or 48 h. The maturation rate in the oocytes from the adult whales (34.2%) tended to be higher than that of the oocytes from the prepubertal whales (19.6%), but there was no significant difference. Following ICSI, 3 out of the 10 inseminated and cultured oocytes from the adult whales cleaved (2-, 8-, and 16-cell stages); all of these oocytes had been matured for 40 in culture. However, these oocytes did not develop to further stages. Only one of the 6 oocytes derived from the prepubertal whales, IVM cultured for 40 h and inseminated, developed to the 4-cell stage. The present results indicate that a 40 h IVM culture produces significantly higher rates of in vitro maturation than a 30 h IVM culture for common minke whale oocytes. Following ICSI, some oocytes cleaved to the 16-cell stage, but no further development was observed.     

The pattern of ovarian development in the prepubertal antarctic minke whale (Balaenoptera bonaerensis)

This study describes the morphological and morphometrical changes associated with prepubertal ovarian development in the Antarctic minke whale (Balaenoptera bonaerensis). Ovaries were harvested from 94 immature minke whales caught in the Antarctic Ocean during the summer feeding season (December-March). Notable differences in ovarian size and morphology were found among animals. Up to 10 folds difference in ovarian weight was found among prepubertal whales of similar body size. During the prepubertal period, ovaries grew slowly and approximately doubled their weight. The morphologies of right and left ovaries were almost identical while the growth of the ovary appears to occur preferentially on the right side. The most striking morphological feature was numerous small antral follicles less than 5 mm in diameter found in ovaries of younger immature whales. The occurrence of these ovaries was highest in whales less than 6 m long and gradually decreased as body length increased. In larger whales, the occurrence of ovaries with a smaller number of follicles up to 10 mm and thick tunica albuginea increased. Thus, the ovary of the Antarctic minke whale experiences bursts of small follicular development during the early prepubertal period before becoming a more developed ovary with fewer but larger follicles, and thick tunica albuginea.     

Relationship between serum sex hormone concentrations and histology of seminiferous tubules of captured baleen whales in the Western North Pacific during the feeding season

The present study was conducted to obtain new information on relationships among serum testosterone (T), estradiol-17 beta (E(2)), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) concentrations and histology of seminiferous tubules in captured common minke and Bryde's whales during the feeding season. Blood samples and testes were collected from common minke (n=39 for blood samples, n=15 for testes) and Bryde's (n=14 for blood samples, n=7 for testes) whales captured from May 2001 to August 2001 in the Western North Pacific. Serum T concentrations, in 35.9% of the common minke and 57.1% of Bryde's whales, were below the detection limit (< 2.5 pg/ml). There were no significant differences in the serum concentrations of E(2), FSH, and LH among immature, mature common minke and Bryde's whales except that LH levels of immature Bryde's whales was higher than those of common minke whales. In most seminiferous tubules of mature whales, only a single-layer of spermatogonia was observed. However, spermatozoa were observed in seminiferous tubules in 2/13 of mature common minke and 4/4 of mature Bryde's whales with the low or undetectable T levels. These results indicate that the low serum T concentrations reflect the inactivity of spermatogenesis in both baleen whales, and that it is not possible to assess gonadal activity in either common minke or Bryde's whales using serum sex hormone concentrations during the feeding season.     

Structure and functions of the placenta in common minke (Balaenoptera acutorostrata), Bryde’s (B. brydei) and sei (B. borealis) whales

The structure and functions of placentas were examined in 3 species of rorqual whales, common minke (Balaenoptera acutorostrata), Bryde’s (B. brydei) and sei (B. borealis) whales, with the aim of confirming the structural characteristics of the chorion, including the presence of the areolar part, and clarifying steroidogenic activities and fetomaternal interactions in the placentas of these whales. Placentas were collected from the second phase of the Japanese Whale Research Program under Special Permit in the North Pacific (JARPN II). Histological and ultrastructural examinations revealed that these whale placentas were epitheliochorial placentas with the interdigitation of chorionic villi lined by monolayer uninucleate cells (trophoblast cells) and endometrial crypts as well as folded placentation by fold-like chorionic villi. Moreover, well-developed pouch-like areolae were observed in the placentas, and active absorption was suggested in the chorionic epithelial cells of the areolar part (areolar trophoblast cells). Berlin blue staining showed the presence of ferric ions (Fe³⁺) in the uterine glandular epithelial cells and within the stroma of chorionic villi in the areolar part. An immunohistochemical examination revealed tartrate-resistant acid phosphatase (TRAP; known as uteroferrin in uteri) in the cytoplasm of glandular cells and areolar trophoblast cells. This result suggested that, in cetaceans, uteroferrin is used to supply iron to the fetus. Furthermore, immunoreactivity for P450scc and P450arom was detected in trophoblast cells, but not in areolar trophoblast cells, suggesting that trophoblast cells synthesize estrogen in whale placentas. Therefore, we herein immunohistochemically revealed the localization of aromatase and uteroferrin in cetacean placentas during pregnancy for the first time.     

Validation of the sperm quality analyzer and the hypo-osmotic swelling test for frozen-thawed ram and minke whale (Balaenoptera bonarensis) spermatozoa

The object of the present study was to investigate the validation of the sperm quality analyzer (SQA) and the hypo-osmotic swelling (HOS) test with standard sperm analysis methods in frozen-thawed ram and minke whale spermatozoa. In rams, highly significant correlations were observed in the percentage of motile spermatozoa (P<0.01) and sperm concentration (P<0.01) between the standard and SQA methods. But, the percentage of morphologically normal spermatozoa did not significantly correlate between the standard and SQA methods. The percentages of swollen spermatozoa at 15 minutes by the HOS test were significantly correlated with the motility by the standard (P<0.05) and by the SQA (P<0.05) methods. For minke whale spermatozoa, the SVI (sperm viability index) values by the standard method were significantly (P<0.001) correlated with the sperm motility index (SMI) values by SQA. The percentage of motile spermatozoa was also significantly correlated (P<0.01) with the motility measured by SQA. Using different hypo-osmotic solutions and incubation times, the HOS test with 25, 100 and 150 mOsM did not show significant variations. Motility observed by the standard method and the percentage of swollen spermatozoa were significantly correlated (P<0.05). These results indicate that the SQA and HOS test can be utilized to assess the post-thawing motility of ram and minke whale spermatozoa, and that the SQA and HOS test values are significantly correlated in ram spermatozoa. However, sperm concentration and morphologically normal spermatozoa are not assessed accurately by SQA in minke whales.     

Evidence of Brucella infection in marine mammals in the North Atlantic Ocean.

Between 1983 and 1996 a total of 1386 samples of serum were taken from four species of seal and three species of whale in the waters west of Iceland, the area of pack-ice north-west of Jan Mayen, the northern coast of Norway and the Kola Peninsula, the waters west of Svalbard, and the Barents Sea; they were tested for the presence of anti-Brucella antibodies with an indirect ELISA (protein G conjugate). The positive sera were re-tested with classical brucellosis serological tests, such as the serum agglutination test, the EDTA-modified serum agglutination test, the Rose Bengal test, and the complement fixation test, as well as an anti-complement ELISA. Anti-Brucella antibodies were detected in all the species investigated, except for the bearded seal (Erignathus barbatus), with the following prevalences: hooded seals (Cystophora cristata) 35 per cent; harp seals (Phoca groenlandica) 2 per cent; ringed seals (Phoca hispida) 10 per cent; minke whales (Balaenoptera acutorostrata) 8 per cent; fin whales (Balaenoptera physalus) 11 per cent; and sei whales (Balaenoptera borealis) 14 per cent. An isolate belonging to the genus Brucella was obtained from the liver and spleen of one of the seropositive minke whales. The findings suggest that antibodies against the surface lipopolysaccharide of Brucella species are widely distributed among marine mammals in the North Atlantic Ocean.     

Structure and Steroidogenesis of the Placenta in the Antarctic Minke Whale (Balaenoptera bonaerensis)

There are few reports describing the structure and function of the whale placenta with the advance of pregnancy. In this study, therefore, the placenta and nonpregnant uterus of the Antarctic minke whale were observed morphologically and immunohistochemically. Placentas and nonpregnant uteri were collected from the 15th, 16th and 18th Japanese Whale Research Programme with Special Permit in the Antarctic (JARPA) and 1st JARPA II organized by the Institute of Cetacean Research in Tokyo, Japan. In the macro- and microscopic observations, the placenta of the Antarctic minke whale was a diffuse and epitheliochorial placenta. The chorion was interdigitated to the endometrium by primary, secondary and tertiary villi, which contained no specialized trophoblast cells such as binucleate cells, and the interdigitation became complicated with the progress of gestation. Furthermore, fetal and maternal blood vessels indented deeply into the trophoblast cells and endometrial epithelium respectively with fetal growth. The minke whale placenta showed a fold-like shape as opposed to a finger-like shape. In both nonpregnant and pregnant uteri, many uterine glands were distributed. The uterine glands in the superficial layer of the pregnant endometrium had a wide lumen and large epithelial cells as compared with those in the deep layer. On the other hand, in the nonpregnant endometrium, the uterine glands had a narrower lumen and smaller epithelial cells than in the pregnant endometrium. In immunohistochemical detection, immunoreactivity for P450scc was detected in most trophoblast cells, but not in nonpregnant uteri, suggesting that trophoblast epithelial cells synthesized and secreted the sex steroid hormones and/or their precursors to maintain the pregnancy in the Antarctic minke whale.     

Pathological and serological evidence of Brucella-infection in baleen whales (Mysticeti) in the western North Pacific

Abnormal testes and uterus were observed in 13 males (33%) and one female (3%) out of 40 common minke whales (Balaenoptera acutorostrata) in the western North Pacific. Similar lesions were found in testis and ovary, respectively, in one male (2%) and female (2%) out of 43 Bryde's whales (Balaenoptera edeni) in the western North Pacific. Grossly, granular lesions with caseation and calcification were main pathological signs, and they were restricted to reproductive organs of mature whales. Chronic purulent or granulomatous orchitis was observed by microscopic analysis. Antibodies to Brucella species were detected in the serum samples of 15/40 (38%) of common minke whales and 4/43 (9%) of Bryde's whales. Neither pathological nor serological change was found in the examined sperm whales (Physeter macrocephalus) in the western North Pacific and Antarctic minke whales (Balaenoptera bonaerensis). These results strongly suggest that Brucella infection was involved in two species of baleen whales (Mysticeti) in the North Pacific.     

Review of welfare concerns relating to commercial and special permit (scientific) whaling

This paper reviews recent data relating to the efficiency and humaneness of the methods used to kill minke whales in commercial and special permit whaling operations. In the 1980s a grenade-headed harpoon was developed for minke whaling. Most recent results indicate that in the Norwegian industry approximately 60 per cent of whales were considered to be killed immediately by this harpoon, with 40 per cent being wounded. However, in Japanese whaling operations, generally only 30 per cent of whales were killed immediately, with 70 per cent being wounded. In both operations, more than six minutes elapsed before half the wounded whales were pronounced dead, with some whales surviving for more than an hour after being harpooned. Many of the long killing times were associated with a failure of a part of the whaling equipment     

Attempt at in vitro maturation of minke whale (Balaenoptera Bonaerensis) oocytes using a portable CO2 incubator

The present study was conducted to investigate whether a portable CO2 incubator was effective for in vitro maturation (IVM) of bovine, porcine and minke whale oocytes, and the effect of maturation media supplemented with different hormones; porcine follicle stimulating hormone (pFSH), estradiol-17beta (E2), or pregnant mare's serum gonadotropin (PMSG): human chorionic gonadotropin (hCG) for minke whale immature oocytes was also examined. In vitro maturation rates of bovine and porcine oocytes cultured in the portable CO2 incubator were not significantly different from the standard CO2 incubator. In minke whale IVM culture using the portable incubator, the maximum expansion of cumulus mass was observed by pFSH/E2 and PMSG/hCG at the end of IVM culture. Moreover, the IVM culture period was shortened to 28-30 h from 96-120 h previously reported. The proportion of matured oocytes cultured in the medium supplemented with pFSH/E2 (26.7%) was significantly higher (P<0.05) than that with PMSG/hCG (6.9%). The present study indicates that a portable CO2 incubator is a useful device for minke whale IVM culture on a research base ship, and the addition of pFSH/E2 into an IVM medium enhanced cumulus expansion and the proportion of minke whale matured oocytes.     

Community-based population monitoring for large baleen whales: the case study of Bryde's whale in Beibu Gulf of China

Citizen science is a popular method for the long-term monitoring of the distribution of wild animals. The application of these methods in different species and environments still poses challenges, especially for aquatic animals. In this study, we investigated the distribution of the Bryde's whale (Balaenoptera edeni) in the Beibu Gulf of China by using scientific boat-based surveys and citizen science approaches using 2 different methods of data collection. First, we built our mobile app (Whale Guard) and installed it on fishermen's phones. Second, we used a popular instant messaging app (WeChat) to create an online fisherman community. We found that the mobile phone app collected far fewer reports (5 reports) than the online community group (42 reports, P < 0.01). By using a variety of incentives, we maintained the fisherman's community's activity without significant user loss (P < 0.01). We also found that the locations collected by social media applications in this study were consistent with observations from scientific boat-based transect surveys. The sightings distribution of Bryde's whales differed from those in previous surveys in that they were present across larger areas. Social media apps reported that 69% of reports was confirmed by more than one person, whereas Whale Guard reports were much lower (0, P <0.001). Community-based citizen science can greatly contribute to the long-term monitoring of Bryde's whales, and it has successfully overcome the challenges of data accessibility, accuracy, and fragmentation. Our study shows how to appropriately use citizen science in different community groups and community-based approaches make them useful for large baleen whale surveys.     

Cetacean occurrence and diversity in whale-watching waters off Mirissa,Southern Sri Lanka

Scientific information is vital to the conservation of cetaceans and the management of whale-watching activities. The southern coastal waters of Sri Lanka are near a narrow continental shelf and biologically abundant in cetacean species. Although the occurrence of cetaceans has been investigated in certain waters of Sri Lanka, few surveys have been conducted along the southern coast. To fill this gap, we conducted boat-based surveys from January to May 2017 to investigate the occurrence, diversity, and behavior of cetaceans in the waters off Mirissa, covering a survey area of 788.9 km². During 55 survey days, we recorded a total of 242 cetacean sightings and identified at least 9 species (3 mysticetes and 6 odontocetes). The blue whale was the most common mysticete species (167 of 174 mysticete encounters), followed by the Omura's whale (4 of 174) and Bryde's whale (3 of 174). The spinner dolphin was the most common odontocete species (28 of 68 odontocete encounters), followed by the sperm whale (18 of 68), common bottlenose dolphin (13 of 68), short-finned pilot whale (5 of 68), melon-headed whale (2 of 68), and killer whale. Blue whales and sperm whales exhibited a clear preference for outer shelf and high slope areas, and blue whales were observed feeding along these waters. The present study provides near-baseline information on cetacean occurrence and diversity in whale-watching waters off southern Sri Lanka, and highlights the urgent need for proper management strategies for whale-watching activities.     

Immunohistological distributions of fibronectin, tenascin, type I, III and IV collagens, and laminin during tooth development and degeneration in fetuses of minke whale, Balaenoptera acutorostrata.

The immunohistological distributions of fibronectin, tenascin, type I, III and IV collagens, and laminin were observed in the tooth buds of fetuses of minke whale, Balaenoptera acutorostrata. Distributions of extracellular matrices (ECMs) examined in this study except for tenascin were generally similar to those of terrestrial mammalian species during development of the tooth bud. Tenascin in the fetuses of minke whale showed characteristic distributions in the dental lamina and the enamel organ in the early tooth developmental stage. In the physiological degeneration stage of tooth bud development, immunoreactivity of the ECMs were very weakly and limitedly detected in the dental papilla and the surrounding mesenchyme. Immunoreactivity of tenascin and type I and III collagens were positively detected in the developing baleen plate germ which was associated with the degenerating tooth bud. These findings suggested that expressions of the ECMs were related to the formation of the tooth bud and baleen plate germ, and that the lack of the ECMs was related to the degeneration of the tooth bud in the fetal minke whale.     

中国水域喙鲸类的研究

中国水域发现的喙鲸科中柯氏喙鲸、贝氏喙鲸、银杏齿中喙鲸、柏氏中喙鲸和朗氏中喙鲸等5种喙鲸的形态鉴别特征及其在中国的分布概况,其中柯氏喙鲸为中国内地沿岸鲸类新记录,朗氏中喙鲸为中国水域（包括台湾）鲸类新记录。     

Diel differences in blue whale (Balaenoptera musculus) dive behavior increase nighttime risk of ship strikes in northern Chilean Patagonia

The northern Chilean Patagonia region is a key feeding ground and a nursing habitat in the southern hemisphere for blue whales (Balaenoptera musculus). From 2014 to 2019, during 6 separate research cruises, the dive behavior of 28 individual blue whales was investigated using bio-logging tags (DTAGs), generating ≈190 h of data. Whales dove to significantly greater depths during the day compared to nighttime (day: 32.6 ± 18.7 m; night: 6.2 ± 2.7 m; P < 0.01). During the night, most time was spent close to the surface (86% ± 9.4%; P < 0.01) and at depths of less than 12 m. From 2016 to 2019, active acoustics (scientific echosounders) were used to record prey (euphausiids) density and distribution simultaneously with whale diving data. Tagged whales appeared to perform dives relative to the vertical migration of prey during the day. The association between diurnal prey migration and shallow nighttime dive behavior suggests that blue whales are at increased risk of ship collisions during periods of darkness since the estimated maximum ship draft of vessels operating in the region is also ≈12 m. In recent decades, northern Chilean Patagonia has seen a large increase in marine traffic due to a boom in salmon aquaculture and the passenger ship industry. Vessel strike risks for large whales are likely underestimated in this region. Results reported in this study may be valuable for policy and mitigation decisions regarding conservation of the endangered blue whale.     

Killing times of minke whales in the Norwegian coastal whaling in the 1981 and 1982 seasons

During the whaling seasons of 1981 and 1982 16 inspectors were on the whaling grounds to collect data about weapons and equipment, shooting facilities, hitting areas, reaction to hits, tissue and organ damage and killing times. The inspectors were instructed to confirm the criteria of death by personal observation before reading the time. Consequently the recorded times are appreciably longer than real killing time for a number of whales. The average killing time according to this method was 11 min 50 sec in the 1981 season and 12 min 40 sec in the 1982 season (Table I). 22.4% and 21.8% died instantaneously in the two seasons. Hitting the CNS or the heart was most effective. Hits in the abdominal cavity or the musculature prolonged the killing times considerably.     

Pathological findings and probable causes of the death of Stejneger’s beaked whales (Mesoplodon stejnegeri) stranded in Japan from 1999 and 2011

One hundred and twenty stranding events of Stejneger’s beaked whales were reported in Japan between 1999 and 2011. The purpose of this study is to introduce pathological data and to discuss probable causes of death for 44 Stejneger’s beaked whales among them. The significant pathological findings were the pulmonary edema, parasitic granulomatous nephritis, emaciation, amyloidosis, suppurative bronchopneumonia and so on. The probable causes of death were categorized as noninfectious in 43 of the cases, which included drowning, starvation and secondary amyloidosis. One individual was diagnosed with septicemia, which was the only example of an infectious disease. Because we could not always perform advanced analyses, such as microbiology tests, biotoxin examinations or contaminant analyses, the finality of our findings may be impaired. However, the present study has broad implications on the causes of death of Stejneger’s beaked whales of the seas around Japan, which are valuable for the future studies and for the detection of emerging diseases.