育仔放棄されたネズミイルカの初乳の成分分析と人工哺育の試み

The harbor porpoise is a marine mammal rarely seen in aquariums. The ecology of this species is not well known, and captive breeding is difficult without essential information such as milk composition, amount consumed and frequency nursed per day, and lactation period. At the Otaru Aquarium in Japan, several deliveries of harbor porpoise offspring have occurred, but the calves have not survived. In the present study, we analyzed the colostrum of a harbor porpoise and attempted to hand-rear a calf using artificial milk after the mother denied nursing. The crude fat and crude protein contents of the colostrum were relatively high compared to values for other odontocetes. The present information will be helpful for future efforts to hand-rear harbor porpoises.本研究では，おたる水族館で育仔放棄されたネズミイルカ幼獣の人工哺育を試みた。生後14日で幼獣は死亡したが，母獣から貴重な初乳を得た。ハクジラ類の中でも本種は授乳期間が短いが，成分分析の結果，その初乳には粗脂肪と粗蛋白質が豊富に含まれていた

The effects of visual impediment on the approaching behavior of harbor porpoise, Phocoena phocoena

Studies on odontocetes (e.g., porpoises) have revealed that these animals may adaptively use vision. The present study examined the contributions of vision to the approaching behavior of the harbor porpoise (Phocoena phocoena). When a porpoise approached a target, the time-to-contact perceived by the animal and its trajectory with a visual impediment condition were compared with those in the control (no impediment) condition. The results suggested that approaching behavior to a stationary target was guided by the animal's evaluation of time-to-contact (tau), maintaining the time derivative of tau ((tau) Over dot) at a constant value. A porpoise with visual deprivation exhibited grater (tau) Over dot) value and a longer evaluation time before contact than a porpoise that was not blindfolded in the task of reaching for the target. Furthermore, the porpoise with a visual impediment changed its swimming trajectory toward a target less than the control, which appeared to adaptively adjust its approaching trajectory. These findings imply that the use of vision aided echolocation and enables precise control and alteration of the trajectory during the approach. The present study has implications for adaptive use of vision during approaching behavior in the harbor porpoise

Survey of ophthalmic disorders among captive pinnipeds in Japan

Pinnipeds have evolved enlarged ocular bulbs to catch fish in the dark. However, their large protruding eyes are easily damaged, which increases the risk of blindness and death in these animals. In captivity, ophthalmic disorders, manifested as keratitis and cataracts, are common among pinnipeds. In this study, we investigated symptoms of ophthalmic disorders in pinniped species using a questionnaire distributed to 32 zoos and aquariums throughout Japan. We conducted this study in cooperation with the Japanese Association of Zoos and Aquariums. The survey included 295 pinnipeds from four otariid species, five phocid species, and one odobenid species. Of these, 43.1% of the pinnipeds had diseases affecting the lens, cornea, and/or other eye parts. Age was positively associated with lens disorders in California sea lions, South American sea lions, and spotted seals. Conflicts and public appearances were also associated with corneal and/or lens disorders in California sea lions. Treatments were evaluated as effective for corneal disorders and conjunctivitis. The results of this study indicate that ophthalmic disorders in pinnipeds are related to the conditions of their captive environment. Aquariums and zoos should be encouraged to share information regarding optimal maintenance practices to improve the living conditions of pinnipeds