21 Result(s)

Article

Spawning habitat characteristics and egg mortality in relation to river geomorphology and run-times of chum salmon (Oncorhynchus keta) in a metropolitan river system, northern Japan

We investigated the geomorphology and environmental variables in which early- and late-run chum salmon groups spawn in an urban section of the Toyohira River, northern Japan, in relation to egg mortality, wher...

Nozomi Aruga, Kentaro Morita, Makoto Aruga… in Environmental Biology of Fishes (2023)

Article

Reverse migration of adult pink salmon (Oncorhynchus gorbuscha) to the sea after their return to fresh water

Few studies have examined the movement of adult Pacific salmon Oncorhynchus spp. between the sea and rivers after they have entered a river. In this study, archival tags that recorded temperature and salinity wer...

Kentaro Morita in Environmental Biology of Fishes (2022)

Article

Size-selective mortality occurs in smolts during a seaward migration, but not in river residents, in masu salmon (Oncorhynchus masou)

Salmonid fish often experience size-selective mortality when descending the river (i.e., seaward migration). However, it is unknown whether size-selective mortality is specific to this life history (i.e., migr...

Ryo Futamura, Kentaro Morita, Yoichiro Kanno… in Environmental Biology of Fishes (2022)

Article

Occurrence of mature male white-spotted charr (Salvelinus leucomaenis) in spring, an unusual season

Ryo Futamura, Kentaro Morita, Koume Araki, Masato Ayumi… in Ichthyological Research (2022)

Article

Japanese eel at the northern edge: glass eel migration into a river on Hokkaido, Japan

Kentaro Morita, Mari Kuroki in Ichthyological Research (2021)

Article

Ongoing localized extinctions of stream-dwelling white-spotted charr populations in small dammed-off habitats of Hokkaido Island, Japan

Habitat fragmentation caused by damming can greatly reduce the population viability of aquatic organisms, with smaller fragmented populations at higher risk of extinction due to increased demographic, genetic,...

Kentaro Morita, Genki Sahashi, Masaki Miya, Shouko Kamada, Takashi Kanbe… in Hydrobiologia (2019)

Article

Spatial and temporal changes in genetic structure and diversity of isolated white-spotted charr (Salvelinus leucomaenis) populations

In Japan, numerous artificial dams constructed for erosion control or hydroelectric power generation have affected almost all rivers and resulted in isolation and fragmentation of many freshwater fish populati...

Shoichiro Yamamoto, Kentaro Morita, Genki Sahashi in Hydrobiologia (2019)

Article

Spatial expansion and increased population density of masu salmon parr independent of river restoration

Spatial expansion and increased population abundance of masu salmon Oncorhynchus masou have been recently reported following habitat restoration in some rivers, but no studies have examined these types of changes...

Genki Sahashi, Kentaro Morita, Daisuke Kishi in Ichthyological Research (2018)

Article

Altitudinal niche partitioning between white-spotted charr (Salvelinus leucomaenis) and masu salmon (Oncorhynchus masou) in a Japanese river

White-spotted charr (Salvelinus leucomaenis) typically occupy the upstream reaches of Japanese streams, whereas masu salmon (Oncorhynchus masou) are generally found downstream. Temperature varies predictably with...

Kentaro Morita, Genki Sahashi, Jun-ichi Tsuboi in Hydrobiologia (2016)

Article

Potential threat of introduced rainbow trout Oncorhynchus mykiss to native salmonids in the western part of Hokkaido, Japan

We obtained the following five results in 10 rivers while elucidating the potential threat of introduced rainbow trout to native salmonids. First, native salmonid density decreased with increasing trout densit...

Genki Sahashi, Kentaro Morita in Ichthyological Research (2016)

Article

Differential effects of the environment on the growth of arabesque greenling (Pleurogrammus azonus): does rising temperature benefit young but not old fish?

Annual and spatial variations in the growth condition of the arabesque greenling (Pleurogrammus azonus) were examined in relation to temperature and food availability. We found age-dependent effects of temperatur...

Shoko H. Morita, Kentaro Morita, Tomonori Hamatsu… in Environmental Biology of Fishes (2015)

Article

Fall–winter collection of two salmonid species: seasonal changes in population densities in four tributaries of the Kushiro river system

Genki Sahashi, Kentaro Morita in Ichthyological Research (2014)

Article

Sex-biased dispersal and growth in sablefish (Anoplopoma fimbria) in the northeastern Pacific Ocean

To examine the potential linkage between sex-biased growth and dispersal in demersal fish, we studied the movement distance and growth of tag-recaptured sablefish (Anoplopoma fimbria). Tagging was conducted by te...

Shoko H. Morita, Kentaro Morita, Akira Nishimura in Environmental Biology of Fishes (2012)

Article

Seasonal changes in stream salmonid population densities in two tributaries of a boreal river in northern Japan

We examined seasonal changes in population densities of stream salmonids (masu salmon Oncorhynchus masou, white-spotted charr Salvelinus leucomaenis, and rainbow trout O. mykiss) in two tributaries of the Shoro R...

Kentaro Morita, Shoko H. Morita, Toru Nagasawa in Ichthyological Research (2011)

Article

Habitat fragmentation by damming threatens coexistence of stream-dwelling charr and salmon in the Fuji River, Japan

Habitat fragmentation by damming can affect the persistence of single species population and also coexistence of two or more species through intensified competition. This study examined the effects of habitat ...

Jun-ichi Tsuboi, Shinsuke Endou, Kentaro Morita in Hydrobiologia (2010)

Article

Offshore Dolly Varden charr (Salvelinus malma) in the North Pacific

Many studies have investigated the ecology of charrs in freshwater, however, little is known about charrs in the ocean. This study examined the distribution, seasonal abundance, and some biological features of...

Kentaro Morita, Shoko H. Morita, Masa-aki Fukuwaka… in Environmental Biology of Fishes (2009)

Article

Evidence of downstream migration of Sakhalin taimen, Hucho perryi, as revealed by Sr : Ca ratios of otolith

The migratory history of Sakhalin taimen, Hucho perryi, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith by using wavelength dispersive X-ray spectrometry on an electron microprobe. ...

Takaomi Arai, Aya Kotake, Kentaro Morita in Ichthyological Research (2004)