Title: VERTICAL DISTRIBUTION, DIEL VERTICAL MIGRATION, AND ABUNDANCE OF SOME MESOPELAGIC FISHES IN THE EASTERN SUBARCTIC PACIFIC OCEAN IN SUMMER 1
Abstract:Vertical distributions ofmyctophid fishes and other components of the mesopelagic micronekton were determined during the summers of 1973-75 at two stations in the eastern subarctic Pacific Ocean. Stra...Vertical distributions ofmyctophid fishes and other components of the mesopelagic micronekton were determined during the summers of 1973-75 at two stations in the eastern subarctic Pacific Ocean. Stratified samples were collected with a multiple net Tucker trawl so that the entire water column extendingtobetween 385 and460 m could be sampled during a daytimeor nighttime period; two to four day and night vertical series ofsamples were obtained each summer. Four species ofmyctophids made up 87% of the total fish catch: Stenobrachius leucopsarus and Diaphus theta. which performed diel vertical migrations of300 m vertical extent; andProtomyctophumthompsoni andS. nannochir.which exhibited only slight diel variation in vertical distribution. Populations of each myctophid species tended to be vertically stratified by age or size with larger individuals occurring in samples taken progressively deeper. Two other major components of the micronekton were euphausiids and decapod shrimps. chiefly Euphausia pacifica and Sergestes similis; both species were conspicuous diel vertical migrators. Samples collected in horizontal hauls immediately following sunset showed that three migratory species. the two migratory myctophids and E. pacifica, were closely associated with the single migratory sound-scattering layer (12 kHz); S. simi/is lagged the ascent of the migratory scattering layer. A single. deep. nonmigratory sound-scattering layer corresponded closely to the distribution of P. thompsoni during both day and night. As in other subpolar oceanic waters. abun dance and standing stock of myctophids were high-0.9 fish/m' and 0.37 g dry weightlm2 • In 1973 we began a field study of some small mesopelagic fishes of the family Myctophidae, commonly known as lanternfishes or myctophids, in the eastern subarctic Pacific Ocean. The objec tives of the study were to determine the vertical distribution and migration characteristics of the numerically dominant species, to document their feeding behavior, and to ascertain if the distribu tions of fish were in any way influenced by the distribution of their preferred prey. Myctophids are major components of the mesopelagic fauna throughout the world ocean. and in most areas they are sufficiently abundant and stratified in the water column to cause deep sound-scattering layers (Baird et al. 1974; McCartney 1976). In deed, study of these fishes has been heavily oriented towal'd aspects of their distribution in relation to sound-scattering layers I e.g., Tucker 1951; Barham 1966; Taylor 1968; Holton 1969; Farquhar 1971; Baird et al. 1974), although some investigations emphasized aspects of biologicalRead More
Publication Year: 1979
Publication Date: 1979-01-01
Language: en
Type: article
Access and Citation
Cited By Count: 54
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot