Abundance and diurnal vertical distribution of fish larvae in early spring and summer in a fjord at South Georgia

1992 ◽  
Vol 4 (4) ◽  
pp. 405-412 ◽  
Author(s):  
A. W. North ◽  
A. W. A. Murray
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Fish Larvae ◽  
Abundant Species ◽  
Early Spring ◽  
Distinct Pattern ◽  
South Georgia ◽  
Gobionotothen Gibberifrons ◽  
Lepidonotothen Larseni ◽  
Distribution Of Fish

The diurnal vertical distribution and abundance of fish larvae was studied by net samples in the 265 m deep fjord of Cumberland East Bay, South Georgia. In early spring the six most abundant species of fish larvae in the upper 200 m of the water column were Champsocephalus gunnari, Lepidonotothen nudifrons, Pseudochaenichthys georgianus, Chaenocephalus aceratus, Parachaenichthys' georgianus and Electrona antarctica. In summer, the larvae of C. gunnari, Gobionotothen gibberifrons, Lepidonotothen larseni and Trematomus hansoni were most abundant, and the majority were found in the upper 140 m of the water column, with greatest densities in the top 2m. During both seasons most species showed some evidence of diurnal vertical migration. A distinct pattern was found for C. gunnari in summer; they were at 0–20 m during the day and 60–100 m at midnight. Net avoidance by the larvae of most species was greater before sunset in early spring, and during all periods of daylight in summer, than at other times of day.

scholarly journals Vertical distribution of fish larvae in the Canaries-African coastal transition zone in summer

2006 ◽  
Vol 149 (4) ◽  
pp. 885-897 ◽  
Author(s):  
J.M. Rodríguez ◽  
S. Hernández-León ◽  
E.D. Barton
Keyword(s):  
Vertical Distribution ◽  
Transition Zone ◽  
Fish Larvae ◽  
Distribution Of Fish

Diel vertical distribution of fish larvae during the winter-mixing period in the Northwestern Mediterranean

2004 ◽  
Vol 61 (8) ◽  
pp. 1243-1252 ◽  
Author(s):  
A. Sabatés
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Fish Species ◽  
Fish Larvae ◽  
Distribution Patterns ◽  
Diel Variation ◽  
Surface Layers ◽  
Light Levels ◽  
Vertical Distributions ◽  
The Vertical Distribution

Abstract The vertical distributions of the larvae of shelf and oceanic fish species that spawn during the winter-mixing period in the Mediterranean are described from 22 vertically stratified plankton tows. Diel differences in the vertical distribution patterns in relation to physical data and potential prey abundance throughout the water column were examined. Even in absence of stratification, the larvae of the various fish species showed different patterns of vertical distribution and diel changes. The larvae of shelf-dwelling species were found in the surface layers, mainly above 50-m depth, and with some exceptions, with very little diel variation in depth distribution. Therefore, the vertical distribution of the larvae of these species coincided with the maximum concentrations of their potential food, nauplii and copepodite stages of copepods. The larvae of mesopelagic fishes showed deeper distributions in the water column and most of these species were located closer to the surface during the day than at night. Given the homogeneity of the physical characteristics throughout the water column, except for light, this behaviour may be determined not only by the higher concentration of prey in the surface layers but also by adequate light levels for feeding.

Fish in the diet of Antarctic fur seals (Arctocephalus gazella) at South Georgia during winter and spring

1996 ◽  
Vol 8 (2) ◽  
pp. 155-160 ◽  
Author(s):  
A.W. North
Keyword(s):  
Arctocephalus Gazella ◽  
South Georgia ◽  
Fur Seals ◽  
Fur Seal ◽  
Total Fish ◽  
Fish Remains ◽  
Gobionotothen Gibberifrons ◽  
Lepidonotothen Larseni ◽  
The Antarctic ◽  
Fish Otoliths

The occurrence of fish in the diet of the Antarctic fur seal (Arctocephalus gazella) at Bird Island, South Georgia was investigated by analysis of fish otoliths in scats (faeces) collected during late May to early November 1983. Of the 55 scats examined, 49 contained fish remains, and 45 contained fish otoliths. Ten fish species were represented by 415 otoliths, and 33 otoliths were too digested to be identified unequivocally. Fish size was estimated from otolith size based on published allometric equations. Four coastal notothenioid fishes dominated the fish component of the diet: Champsocephalus gunnari and Gobionotothen gibberifrons each comprised about 40% of the total fish mass; Chaenocephalus aceratus was ranked third by mass and the smaller Lepidonotothen larseni occurred in one quarter of the scats but was of lower importance in terms of mass. The length-frequency distribution of C. gunnari landed by the commercial fishery in October 1982 to June 1983 is similar to that which comprised the bulk of the diet in the present study. Compared with recent studies on the fish component of the diet in the literature, the dominance of C. gunnari is generally similar, however, there was a greater proportion of G. gibberifrons during the 1983 winter and spring than reported for recent winters.

scholarly journals DISTRIBUTION OF FISH IN THE PREDATOR-PREY SYSTEM IN THE RIVERBED DEPRESSION OF THE LOWER IRTYSH

2017 ◽  
pp. 76-84
Author(s):  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Water Area ◽  
Bottom Surface ◽  
Predator Prey ◽  
Prey System ◽  
Irtysh River ◽  
Riverbed Depression ◽  
Distribution Of Fish ◽  
The Irtysh River

The article presents are features of the horizontal and vertical distribution of fish in the water area of the Kondinskaya riverbed depression in the lower reaches of the Irtysh River (Tyumen region, Russia). There have been considered horizons of the water column from the surface to the bottom: surface-pelagic horizon (< 10 m), 1st pelagic horizon (10-20 m), 2nd pelagic horizon (20-30 m), and bottom-pelagic horizon (> 30 m). Hydroacoustic survey was conducted using a software and hardware complex "AsCor" on board a small ship that moved in tacks (zigzags). The recorded information, including the GPS track, processed with special application software "AsCor". Taxonomic belonging to the families was determined remotely - by the type of the reflected sound. According to the data of echometric sensing, main part of fish population on the studied water area was presented by carp species (Cyprinidae) - 66.81%, perch species (Percidae) - 23.77%, cisco species (Coregonidae) - 5.60%, unrecognized species (sturgeon (Acipenseridae)), eelpout species (Lotidae), pike species (Esocidae)) - 3.82% of the registered plurality of fish. All fish groups of the registered mass in terms of abundance have been distributed predominantly in the surface and 1-st pelagic horizons of the water column of the riverbed depression. The difference in the distribution of registered taxonomic fish groups in the vertical aspect from the surface to the bottom is different: in planktivorous fishes more than 190 times, in predatory fishes from 10 to 27 times. A more even distribution of predatory species reduces their aggressive interaction - interspecific and intraspecific competition. There has been revealed a tendency to decrease the percentage of planktivorous species (Cyprinidae) in each succeeding horizon in direction from the surface to the bottom; for Percidae and Coregonidae species and a group of unrecognized fishes it was established, vice versa, in the direction from the bottom to the surface. Due to the wedge-shaped decrease of the living space in the riverbed, the general tendency of a decrease in the number of fish has been registered in the direction of deeper horizons. There has been noted the statistical reliability of differences in the vertical distribution for all registered fish groups. The features of the fish distribution in the predator-prey system on the Irtysh river section with heterogeneous conditions of the aquatic environment (intensive ascending currents and funnels, significant depth changes) characterize it as a "window of antipredation".

Sign in / Sign up

Export Citation Format

Share Document