The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate a...The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.展开更多
Since 1790, Antarctic living resources were becoming subjects of competition among the exploiters to be first in obtaining the maximum profit from them. This led to subsequent extinction of valuable species from fur s...Since 1790, Antarctic living resources were becoming subjects of competition among the exploiters to be first in obtaining the maximum profit from them. This led to subsequent extinction of valuable species from fur seals and next penguins, large through small whales, industrial demersal fish, further to pelagic species and now toothfish, crabs and krill. Catch proportions of their numerous and biomass decrease. The biomass of South Georgia Icefish estimated for 40 years in spide of decreasing trend has one of the largest components-the oscillations with periods of 3 years or 4 years. Their models explain large biomass fluctuations in the years 1975 to 1981 with amplitudes ±15 × 10^3 tonnes around average 20 ×10^3 tonnes and further decline up to 2005 season with oscillation ±4 ×10^3 tonnes around average 5 × 10^3 tonnes. For future season, 2016 model predicts a little increase of the biomass oscillation at level of 8 × 10^3 tonnes with reduced amplitude 2 × 10^3 tonnes. Slowly increase density of adult fish was also reported for target similar and close related mackerel icefish. Additional references for biomass levels help reduce the risk of further depletion biomass of Pseudochaenichthys georgianus which already declined to 75%. As global warming promote phytoplankton growth, replacing krill fishery by algae farms can save unique Antarctic heritages.展开更多
文摘The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.
文摘Since 1790, Antarctic living resources were becoming subjects of competition among the exploiters to be first in obtaining the maximum profit from them. This led to subsequent extinction of valuable species from fur seals and next penguins, large through small whales, industrial demersal fish, further to pelagic species and now toothfish, crabs and krill. Catch proportions of their numerous and biomass decrease. The biomass of South Georgia Icefish estimated for 40 years in spide of decreasing trend has one of the largest components-the oscillations with periods of 3 years or 4 years. Their models explain large biomass fluctuations in the years 1975 to 1981 with amplitudes ±15 × 10^3 tonnes around average 20 ×10^3 tonnes and further decline up to 2005 season with oscillation ±4 ×10^3 tonnes around average 5 × 10^3 tonnes. For future season, 2016 model predicts a little increase of the biomass oscillation at level of 8 × 10^3 tonnes with reduced amplitude 2 × 10^3 tonnes. Slowly increase density of adult fish was also reported for target similar and close related mackerel icefish. Additional references for biomass levels help reduce the risk of further depletion biomass of Pseudochaenichthys georgianus which already declined to 75%. As global warming promote phytoplankton growth, replacing krill fishery by algae farms can save unique Antarctic heritages.
