Feeding and growth in a captive-born bottlenose dolphin Tursiops truncatus

The feeding and growth of a captive-born bottlenose dolphin Tursiops trunatus calf were studied for 30 months post partum. Changes in the behaviours associated with suckling were monitored and suggested that the mammary glands need tactile stimulation before the calf can feed. The calf exhibited no teat preference and mean duration of each suckling bout (4 s) remained constant throughout the suckling period. Suckling frequency declined rapidly during the first two months and continued decreasing steadily for the remainder of the study. A reduced growth rate from seven months suggests that nutrition obtained only from milk is insufficient; however, growth rate increased from 11 months, after the calf started feeding on fish. Solid food intake increased rapidly until completion of the study, by which time the calf was eating 16 kg of fish daily. Short-term reductions in food intake after weaning resulted in corresponding reductions in weight, but appeared to have no effect on linear growth

Organochlorines in common dolphins caught in shark nets during the Natal ‘sardine run’

The concentrations of organochlorines were determined in blubber and liver samples from common dolphins inhabiting the coastal waters of the south-east coast of southern Africa. Liver levels of PCBs and DDTs are far lower and do not appear directly associated with those in blubber. In males, blubber residue concentrations increased with age but in females a marked rapid decline in concentrations of PCBs and t-DDT was evident between the eighth and eleventh growth layer groups, approximately the age of sexual maturity and subsequent to their first or second ovulation. Lower levels in females are explained through transfer to the new-born calf during lactation and the consequences of this for the newborn calf are discussed

Effect of lactation stage and concurrent pregnancy on milk composition in the bottlenose dolphin

Although many toothed whales (Cetacea: Odontoceti) lactate for 2–3 years or more, it is not known whether milk composition is affected by lactation stage in any odontocete species. We collected 64 pooled milk samples spanning 1–30 months postpartum from three captive bottlenose dolphins Tursiops truncatus. Milks were assayed for water, fat, crude protein (TN × 6.38) and sugar; gross energy was calculated. Ovulation and pregnancy were determined via monitoring of milk progesterone. Based on analysis of changes in milk composition for each individual dolphin, there were significant increases (P<0.05) in fat (in all three dolphins) and crude protein (in two of three), and a decrease (P<0.05) in water (in two of three) over the course of lactation, but the sugar content did not change. In all three animals, the energy content was positively correlated with month of lactation, but the percentage of energy provided by crude protein declined slightly but significantly (P<0.05). At mid-lactation (7–12 months postpartum, n=17), milk averaged 73.0±1.0% water, 12.8±1.0% fat, 8.9±0.5% crude protein, 1.0±0.1% sugar, 1.76±0.09 kcal g−1 (=7.25 kJ g−1) and 30.3±1.3% protein:energy per cent. This protein:energy per cent was surprisingly high compared with other cetaceans and in relation to the growth rates of calves. Milk progesterone indicated that dolphins ovulated and conceived between 413 and 673 days postpartum, following an increase in milk energy density. The significance of these observed compositional changes to calf nutrition will depend on the amounts of milk produced at different stages of lactation, and how milk composition and yield are influenced by sampling procedure, maternal diet and maternal condition, none of which are known

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4) were female. Most patients (n = 3685 84.7%) were from low-and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 62.8%), followed by strabismus (n = 429 10.2%) and proptosis (n = 309 7.4%). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 95% CI, 12.94-24.80, and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 95% CI, 4.30-7.68). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs. © 2020 American Medical Association. All rights reserved

Tidal activity rhythms in the mangrove snail Cerithidea decollata (Linn.) (Gastropoda: Prosobranchia: Cerithiidae)

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Shark predation on Indian Ocean bottlenose dolphins Tursiops truncatus off Natal, South Africa

The incidence of shark induced scars on Indian Ocean bottlenose dolphins caught in gill nets off Natal, on the south-east coast of southern Africa, was monitored between January 1983 and June 1987. The occurrence of dolphin remains in sharks caught in these nets between January 1980 and December 1985 was also recorded. Of the dolphins caught, 10,3% exhibited scars or wounds consistent with shark bites. Only 1,2% of over 6000 sharks caught contained cetacean remains. Four species of shark, the Zambesi (Carcharhinus leucas), the tiger (Galeocerdo cuvieri),the great white (Carcharodon carcharías) and the dusky shark (Carcharhinus obscurvs) were implicated as dolphin predators. Estimates from the number of these four species caught annually and the frequency of occurrence of dolphin flukes and vertebrae in their stomachs suggest that a mininum of 20 bottlenose dolphins or 2,2% of the estimated population in southern Natal coastal waters are killed each year by sharks

Inshore small-mesh trawling survey of the Cape south coast. Part 4. Contributions to the biology of some Teleostei and Chondrichthyes

No Abstract