Scientists from the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences (IEE RAS), the P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences and the Pacific Branch of the All-Russian Research Institute of Fisheries and Oceanography have obtained the first data on the spatial distribution, size composition, age, sex structure, growth and maturation of a poorly studied deep-sea benthopelagic fish species from the waters of the underwater Hawaiian-Emperor seamount chain (northwestern Pacific Ocean) – Coelorinchus gilberti.
Coelorinchus gilberti (Fig. 1) is a member of the Macrouridae family found off the Pacific coast of Japan (from Shikoku to Hokkaido) and on the seamounts of the Kyushu-Palau and Hawaiian-Emperor seamount chain. This species is a fairly common bycatch in the domestic longline fishery for monkfish Erilepis zonifer (Anoplopomatidae) and groupers (Sebastidae) on the Hawaiian-Emperor seamount chain. However, until now, there has been no published information on its distribution and biology.
Fig. 2. Scheme of the research area on the Emperor Ridge seamounts (left) and catches (CPUE – catch per unit effort in specimens per 1000 hooks per 1 hour of line standstill) of Gilbert's coelorinchus Coelorinchus gilberti by bottom longline (right).
Catches of the species under consideration were recorded from the Nintoku Seamount in the north to the Kammu Seamount in the south (Fig. 2) at depths of 215-1840 m, which significantly expands the known bathymetric range of its occurrence. It was most often recorded on the Jingu, Ojin, and Kammu Seamounts. The catches included individuals with a total length of 34-93 cm (average 53.2 cm), body weight of 140-5240 g (average 688.2 g), and ages of 24-48 years (average 37.9 years). Females were significantly larger and older than males and generally dominated the catches (the proportion of males did not exceed 40%). Individuals in spawning condition were recorded in catches only in April, which is probably due to the end of spawning, which is assumed to occur in earlier months.
The conservation status of many representatives of the genus Coelorinchus is assessed by the IUCN (International Union for Conservation of Nature) as Data Deficient or Least Concern. In this regard, many authors recognize the need for a more detailed study of the ecology and biology of representatives of this genus, monitoring of catches, regulation of fisheries, conservation and rational use of their stocks in order to prevent overfishing. In this regard, the obtained data are of undoubted value.
The article was published in the journal: Korostelev, N.B., Volvenko, I.V., Maltsev, I.V., Orlov, A.M. 2025. Brought to the surface from obscurity: the distribution and biology of Coelorhinchus gilberti (Macrouridae, Gadiformes, Teleostei) off the Emperor Seamounts (Northwestern Pacific) // Deep Sea Research Part II: Topical Studies in Oceanography. Article 105461.
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