Possible causes of annual change in the year class strength of flathead flounder Hippoglossoides dubius (Pisces, Pleuronectiformes) in Funka Bay, Hokkaido

スポンサーリンク

概要

• 論文の詳細を見る

• To elucidate the mechanism for the annual fluctuation of year class strength of flathead flounder Hippoglossoides dubius in Funka Bay, Hokkaido, annual changes in age composition, spawning period, egg abundance, food availability at the first feeding stage, and hydrographic conditions were investigated from 1988 to 1999. Strong year classes occurred in 1989, 1991, and 1995. Comparison between annual fluctuations of commercial catch of flathead flounder and the abundance of eggs suggests that there is no relationship between the spawning size and the resultant year class strength of flathead flounder in Funka Bay. The density of copepod nauplii, the primary food for larval flathead flounder, was 7.8 individuals・l^[-1] in January and then increased in February (18.1 individuals・l^[-1]) and March (12.9 individuals・l^[-1]) in 1991. High densities of copepod nauplii in January were also found in 1994 (13.1 individuals・l^[-1]), 1995 (12.3 individuals・l^[-1]), and 1996 (13.8 individuals・l^[-1]). However, the strong year class of flathead flounder did not occur in 1994 and 1996. Therefore, the high density of copepod nauplii does not determine the magnitude of the year class strength of flathead flounder in this area. During the study period the spawning period varied widely among years from January to March and early spawnings were found in the years when the high water temperatures were observed from November to December. The high water temperatures at the surface layer in January were observed in 1991. Relatively warm water were also observed from January to February in 1995, while temperatures during January and February were low in 1989. From the results, it is considered that the early spawning and relatively high water temperature affect the magnitude of the year class of flathead flounder in this area. For the 1989-yaer-calss, high water temperature in mid December 1988 might reduce the mortality during the early life period of flathead flounder in Funka Bay in spite of low temperature after the intrusion the Oyashio Coastal Water (cold water) in January.アカガレイHippoglossoides dubiusは噴火湾における産業的重要種であり，顕著な年級群変動を示すことが知られており，1980年および1983年に卓越年級群が発生している．年級群強度を決定する要因を明らかにする目的で，1989年から1999年までの期間，噴火湾においてアカガレイを採集し，海洋環境を測定した．調査期間中，卓越年級群は1989，1991，および1995年に発生した．これらの年において年級群強度と産卵群の来遊量および産み出された卵の豊度との間に相関がみられないことから，当海域において年級群強度の決定に産卵来遊量および産卵量は大きな影響を及ぼさないと考えられる．摂餌開始期の仔魚の主要餌生物である橈脚類ノープリウスの豊度は1月から3月にかけて増加するが，その逆の年も認められた．橈脚類ノープリウスの豊度と年級群強度との関係から，生活史初期の餌生物環境が年級群強度を支配しているとは考えられない．調査期間中，産卵盛期は1月から3月まで変化しており，産卵直前の11月から12月にかけての海底水温が高い年には産卵期が早くなる傾向が確認された．卓越年級群が発生した年の産卵盛期はいずれも1月で，1月の表層水温は1991年で高く，1995年も比較的暖かかったが，1989年は低かった．過去の調査結果から卓越年級群が発生した1980年および1983年も冬期間の表層水温が高かったことから，摂餌開始期仔魚にとって水温が高いことが生き残りに重要な影響を持つと考えられる．1989年は沿岸親潮の流入が早く，1月の水温が低かったが，前年12月の水温が高かったことから，早期に産み出された仔魚の生き残りが高かったのではないかと予想される．

• 水産海洋学会 = Japanese Society of Fisheries Oceanographyの論文

著者

• MAEDA TSUNEO

  Toyama Prefecture Fisheries Research Institute

• Takatsu T

  Hokkaido Univ. Hokkaido

• Maeda Tatsuaki

  Toyama Prefecture Fisheries Research Institute

• Takatsu T

  Graduate School Of Fisheries Sciences Hokkaido University

• Takatsu Tetsuya

  Hokkaido Univ. Hokkaido Jpn

• Nakatani T

  Graduate School Of Fisheries Sciences Hokkaido University

関連論文

• Comparison of the nutritional transition date distributions of marbled sole larvae and juveniles in Hakodate Bay, Hokkaido
• Molecular-based method to distinguish sympatric deep-sea whelks, Buccinum striatissimum and Buccinum tenuissimum in the Sea of Japan
• Morphological analysis of deep-sea whelk Buccinum tsubai in the Sea of Japan
• Genetic population structure of the deep-sea whelk Buccinum tsubai in the Japan Sea
• Feeding habits of pointhead flounder Cleisthenes pinetorum larvae in and near Funka Bay, Hokkaido, Japan
• Effects of hypoxia on principal prey and growth of flathead flounder Hippoglossoides dubius in Funka Bay, Japan
• Spatial distribution and feeding habits of Pacific cod (Gadus macrocephalus) larvae in Mutsu Bay, Japan
• Feeding habits of Pacific cod larvae and juveniles in Mutsu Bay, Japan
• Annual variation of potential predation impacts on larval and juvenile marbled sole Pseudopleuronectes yokohamae by sand shrimp Crangon uritai in Hakodate Bay, Hokkaido
• Spatial distribution and feeding habits of the shrimp Crangon uritai as a predator on larval and juvenile marbled sole Pleuronectes yokohamae
• Prey choice order of Crangon uritai as a predator for juvenile Pleuronectes yokohamae
• Feeding habits of stone flounder Platichthys bicoloratus larvae in Mutsu Bay, Japan
• Spatial and temporal distribution of Pacific cod Gadus macrocephalus juveniles in Mutsu Bay, Japan
• Maternal effects and larval survival of marbled sole Pseudopleuronectes yokohamae
• Body-Length Shrinkage of Marbled Sole Pseudopleuronectes yokohamae Larvae Preserved in Formalin and in Ethanol Solutions
• Possible causes of annual change in the year class strength of flathead flounder Hippoglossoides dubius (Pisces, Pleuronectiformes) in Funka Bay, Hokkaido
• The Juvenile Cresthead Flounder (Pleuronectes schrenki)：An Occasional Cleaner Occurring in Lake Notoro, Hokkaido
• Age and Growth of Marbled Sole (Pleuronectes yokohamae) in the Coastal Waters of Western Aomori Prefecture, Japan
• Vertical distribution and prey of walleye pollock in the northern Japan Sea
• Age and growth of brown sole Pleuronectes herzensteini in the coastal waters of western Aomori Prefecture, Japan
• STUDIES ON THE EARLY LIFE HISTORY OF WALLEYE POLLOCK THERAGRA CHALCOGRAMMA IN FUNKA BAY AND VICINITY, HOKKAIDO

もっと見る 閉じる

スポンサーリンク