International Marine Biological Research Institute

Chiba, Japan

International Marine Biological Research Institute

Chiba, Japan
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Dewar H.,Southwest Fisheries Science Center | Thys T.,Ocean Sunfish Tagging and Research Program | Teo S.L.H.,University of California at Davis | Farwell C.,Monterey Bay Aquarium Research Institute | And 12 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2010

Twelve ocean sunfish, Mola mola, were tagged with pop-up satellite archival tags off the coast of Kamogawa, Japan during the spring of 2001 and 2003-2006. Transmitted data were obtained from seven tags. An eighth tag was recovered and provided a highly detailed four-month dataset from which several recognizable diving patterns emerged. This M. mola spent considerable time at the surface, possibly warming itself. These apparent basking events were punctuated by regular deep dives below the thermocline to depths as great as 600. m and temperatures as low as 2°C. The vast majority of dives occurred during the day, with relatively little vertical movement at night. Geolocation estimates were possible between tag and release for five individuals. No large, basin-scale movements were apparent with most molas remaining relatively close to their initial tagging location over a six to nine month period. Seasonal movements were apparent for some molas and corresponded to regional shifts in oceanography. Northward movements from the Kuroshio Current into the Kuroshio-Oyashio transition zone and the Oyashio Current during the summer months coincided with an increase in temperature and reduction in chlorophyll a concentrations in waters near central Japan. In the fall, most molas returned inshore to the coast of Japan. Molas are targeted and incidentally captured by fishermen in these waters, and the information presented here is vital for effective fisheries management and to forecast changes in mola behaviors associated with environmental variability. © 2010.

Morita Y.,Hokkaido University | Hiramatsu N.,Hokkaido University | Fujita T.,Hokkaido University | Amano H.,Hokkaido University | And 5 more authors.
Journal of Reproduction and Development | Year: 2013

A single radial immunodiffusion (SRID) assay and a chemiluminescent immunoassay (CLIA) were initially developed for alpha-fetoprotein (AFP) of the striped dolphin. Utilizing these developed assays, we investigated pregnancy-associated changes in the levels of AFP in the sera of fetuses and pregnant females of three dolphin species; samples were either collected from captive individuals or obtained as fishery by-products. The concentrations of AFP in the fetal serum ranged from 419.0 to 2026.3 μg/ml in the striped dolphin, 12.6 to 1218.7 μg/ml (for an AFP equivalent; eqAFP) in the common bottlenose dolphin and 770.6 to 3129.1 μg eqAFP/ml in the Risso's dolphin. AFP levels decreased with increased fetal size in fetuses over 20 cm in length. The concentrations of AFP in sera of pregnant females ranged from 7.18 to 8068.7 ng/ml in the striped dolphin, 6.6 to 1241.1 ng eqAFP/ml in the common bottlenose dolphin and 3.4 to 2868.7 ng eqAFP/ml in the Risso's dolphin. The levels in most pregnant females were equal to or lower than those found in males and nonpregnant individuals, although a few pregnant females exhibited extremely high levels (in the range of hundreds to thousands of nanograms per milliliter). Such high levels of AFP were not observed during pseudopregnancy. To our knowledge, this is the first report on basal profiles for serum AFP levels in small odontocetes. The profiles indicated that AFP may play a significant role during embryonic development, although maternal levels do not appear to be a diagnostic biomarker for monitoring pregnancy. © 2013 by the Society for Reproduction and Development.

Katsumata E.,International Marine Biological Research Institute
Journal of Reproduction and Development | Year: 2010

The reproductive endocrinological characteristics of beluga, killer whale, spotted seal and bottlenose dolphin were evaluated and used in conjunction with applied reproductive research to enhance captive breeding programs. Results from 8 y of biweekly serum progesterone determination in a female beluga indicated that sexual maturity occured at approximately age 13, two to seven estrous cycles, lasting 37 ± 3.9 days, per yr began in April-May every year. Rectal temperature was positively correlated with serum progesterone levels and negatively associated with behavioral estrus. In five cases of pregnancy of two female killer whale, positive relationship was found between serum progesterone concentration and temperature during the first period of 18 month-gestation. In the normal parturitions (n=4), rectal temperature decreased 0.8 C lower than average rectal temperature during pregnancy. Sexual maturity of female killer whales occurred at age nine. Yearly contraception in the monoestrus captive spotted seals (n=10) using a single dose of the progestagen (proligestone™; 5 or 10 mg/kg s.c.) was achieved in 94% (33/35) of the attempts over 5 yr when the hormone was administered two months prior to the breeding season. Artificial insemination trials (n=4) were conducted in female bottlenose dolphin (n=3) using fresh and frozen-thawed semen. Estrus synchronization using regumate (27 days) resulted in ovulation occurring 19 to 24 days post withdrawal. Conception was confirmed in 75% of the attempts, with two females successfully delivering calves. © 2010 by the Society for Reproduction and Development.

PubMed | International Marine Biological Research Institute
Type: Journal Article | Journal: The Journal of veterinary medical science | Year: 2012

This study is the first report on circulating testosterone and inhibin levels in a species of whales, the beluga. Circulating testosterone and immunoreactive (ir-) inhibin levels in two captive male belugas (Nack, originally from Canada and Duke, from the Okhotsk Sea) were measured every month for 9 years between 1995 and 2003. Assuming that clearly increased testosterone levels in the circulation indicates that the belugas had reached sexual maturity, at the ages of 10 (Nack) and 11 years old (Duke). Their testosterone levels before the significant increase (pre-pubertal) were 0.42 0.07 ng/ml (n=18) and 0.35 0.10 ng/ml (n=18) and, those of after the increase (maturity) were 1.65 0.14 ng/m l (n=74) and 2.06 0.14 ng/ml (n=74). Circulating ir-inhibin levels before sexual maturity were 0.78 0.04 ng/ml (n=18) and 0.64 0.04 ng/ml (n=15) and, after sexual maturity were 0.52 0.02 ng/ml (n=56) and 0.43 0.02 ng/ml (n=67). Seasonal changes were observed in the testosterone levels after sexual maturity and the levels increased during March and April in Canadian origin Nack, and peaked in February in Okhotsk origin Duke. Circulating ir-inhibin level gradually decreased as they aged. A negative correlation between the circulating testosterone and ir-inhibin was observed. No seasonal changes were observed in the ir-inhibin levels after sexual maturity. These data will surely correspond to clarification of endocrinology and the successful reproduction of the beluga.

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