CVClient

Tetsumi Takahashi

  (高橋 鉄美)

Profile Information

Affiliation
Professor (Senior Researcher), Institute of Natural and Environmental Sciences, University of Hyogo
Degree
PhD(Dec, 1999, Hokkaido University)

J-GLOBAL ID
202001011489422091
researchmap Member ID
R000010113

Committee Memberships

 2

Papers

 47
  • Shun Satoh, Tetsumi Takahashi, Seiya Okuno, Kento Kawasaka, Mabo Lwabanya
    Fisheries, Feb 7, 2024  
    We conducted an investigation into ghost fishing, a phenomenon in which abandoned fishing equipment remains operational for extended durations, in the southern region of Lake Tanganyika, Republic of Zambia. The perils associated with ghost fishing have achieved international recognition; however, there exists a conspicuous dearth of scholarly investigations in particular regions, notably inland aquatic environments and developing countries. Employing scuba diving for field observations, we discovered that ghost fishing was solely evident in monofilament nylon nets, despite the presence of four different net types in the littoral area of the lake. Notably, endemic crabs Platythelphusa armata and P. maculata from Lake Tanganyika constituted 65.2% of the organisms captured by abandoned nets, with the remainder comprising various fish species. The number of captured organisms exhibited a dependence on the interplay between the length and mesh size of the abandoned nets, indicating that the risk of ghost fishing is heightened when both net and mesh size are substantial. Furthermore, we encountered predatory Spiny Eels Mastacembelus moorii ensnared in nets around their jaws and teeth. Intriguingly, the digestive tract of one of the Spiny Eels contained a partially digested cichlid species entangled in the same nets, strongly suggesting the occurrence of secondary ghost fishing.
  • Tetsumi Takahashi
    Hydrobiologia, 850(10-11) 2385-2392, Oct 19, 2022  Peer-reviewedLead authorLast authorCorresponding author
  • Tetsumi Takahashi, Atsushi J. Nagano, Teiji Sota
    BMC Genomics, 22 615, Aug, 2021  Peer-reviewedLead authorCorresponding author
  • Tetsumi Takahashi
    Hydrobiologia, 848 3655-3665, 2021  Peer-reviewedLead authorCorresponding author
  • Tetsumi Takahashi, Atsushi J. Nagano, Lina Kawaguchi, Norio Onikura, Jun Nakajima, Takuya Miyake, Noriyasu Suzuki, Yoshihiko Kanoh, Tetsuya Tsuruta, Takuya Tanimoto, Yukio Yasui, Noriyuki Oshima, Kouichi Kawamura
    Conservation Genetics, 21(4) 641-652, Aug, 2020  Peer-reviewedLead authorCorresponding author
    Rhodeus ocellatus kurumeus is a small cyprinid fish endemic to the Japanese archipelago. This fish frequently hybridizes with an exotic subspecies Rhodeus ocellatus ocellatus, and non-introgressed populations of R. o. kurumeus have greatly decreased. Previous studies based on mitochondrial and nuclear DNA identified introgressed populations and inferred phylogenetic relationships, but these approaches may lead to underestimates of introgression or ambiguous results owing to the small number of genetic markers used. The present study applied double digest restriction site-associated DNA (ddRAD) sequencing to assignment tests and phylogenetic inferences. Data matrices can vary in size and content depending on the strategies used to process ddRAD sequences; therefore, we prepared 25 data matrices with various processing strategies. The assignment tests based on the 25 data matrices resulted in similar assignment patterns and provided evidence for introgression in some populations that had been identified as non-introgressed populations in previous studies. The maximum-likelihood (ML) phylogenetic trees differed in robustness and topology among the 25 matrices; interestingly, ML trees with low statistical support reflected geographical distributions of fish better than ML trees with high statistical support. These results indicate that ddRAD sequencing can detect introgression with greater sensitivity than conventional DNA markers, that ddRAD sequencing is useful for phylogenetic inference among closely related populations within a subspecies, and that statistically robust ML trees do not necessarily reflect the true phylogeny. Application of ddRAD data to conservation genetics and evolutionary history of this subspecies are also discussed.

Misc.

 11

Books and Other Publications

 6

Presentations

 2

Teaching Experience

 5

Professional Memberships

 5

Research Projects

 14

Academic Activities

 2

Social Activities

 39