冬季の北太平洋亜寒帯水域にさけ・ます類の餌は豊富にあるのか?

Is There Abundant Zooplankton Prey for Salmonids in the Subarctic North Pacific in Winter?

Nagasawa Kazuya

遠洋水産研究所研究報告

Macrozooplankton was sampled using a North Pacific standard plankton net during two trans-Pacific cruises of the R/V Kaiyo maru at 27 and 23 stations in a wide area of the northern North Pacific Ocean in November-December 1992 and January 1996, respectively. In all of the western and central North Pacific and Gulf of Alaska, the macrozooplankton biomass in these winter months was much lower than that in summer months. Salmonids (Oncorhynchus spp.) were captured in waters with low sea surface temperatures (<8 °C), where the macrozooplankton biomass remained quite low as well. The salmonids may have a survival strategy to stay in cold waters in order to reduce their energetic consumption, because macrozooplankton as prey is not abundantly available in winter. The cold-water environment appears to be advantageous to the survival of offshore salmonids overwintering under poor food conditions.

macrozooplankton biomass

subarctic North Pacific Ocean

salmonids

ocean distribution

survival strategy

寒冷地

サケ科

太平洋

餌料

戦略

生存

冬

Zoology [ 480 ]

jpn

遠洋水産研究所

[ISSN] 0386-7285

[NCID] AN00025949

[URI] http://rms1.agsearch.agropedia.affrc.go.jp/contents/library/jnr/enyo.html isVersionOf