Age, Growth and Distribution of the Antarctic Fish Chaenocephalus Aceratus Based on Otoliths

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.

Age, Growth and Distribution of the Antarctic Fish Pseudochaenichthys georgianus Based on Otolith Morphometry

The Ps. georgianus （Pseudochaenichthys georgianus） were sampled in the summer between 1979 and 2009 at South Georgia Island, and at South Shetland Island. The otoliths ofPs. georgianus contained microincrements similar to daily increments in the otoliths of fishes from temperate and tropical waters. The estimated age from microincrements was similar to that inferred from the body length distribution and otoliths mass： age （years） = 81.98 × Otolith Mass （g） - 0.483. Ps. georgianus like all Channichthyidae due to their adoption to cold water, attain rapidly large body in accordance with the parameters of the von Bertalanffy growth equation： L∞ （asymptotic length） = 66.1 cm; K （constant related to coefficient of catabolism） = 0.28; to （age of the fish at initial length） = 0.008 year; L0 （length of the fish at initial age） = 0.15 cm. That fast growth rate （despite the difference in hatching periods between regions at South Georgia Island, and at South Shetland Island） were not changed, confirming, that it is established to cold water by natural selection. Changes of the microincrements growth pattern are described that appear to be related to larval, hatching and metamorphosis, and have similar pattern to those ones previewed in C. aceratus （Chaenocephalus aceratus） and C. gunnarii （Champsocephalus gunnarii）. Larvaes and postlarvaes of that species have similar habitats during early life history, which is reflected in similar otoliths morphology. Width of their daily increments is： 0.0018-0.0028 mm for Ps. georgianus, 0.0015-0.0024 mm for C. gunnarii and 0.001-0.0016 mm for C. aceratus. The age and developments periods of South Georgia＇s icefish （common name and the abbreviation = SGI for Ps. georgianus as this species was found only there in the past） estimated from otolith was validated by their different geographical distribution depending on the currents and the presence of their food-krill in them. Postlarvae and early juvenile stages were concentrated at the south-western side of the island shelves deeper than 200 m, where currents are weaker in comparison to surface and where juvenes and small krill prevail. Older and mature fish, over 3 or 4 years old, were numerous on the north-eastern side of the islands shelves in regions of strong vortices that concentrate krill to high densities. As life in the currents needs greater ability to swimming as a large, mature and 4 years old fish had increased their ability to swim up to 4 times growing and developing from inshore larvae. During that, their otoliths become more flattened （up to 3 times） and elongated for better fulfil its functions in the higher swimming speed. However, similar species C. aceratus and C. gunnari have more flattened and elongated otoliths than Ps. georgianus and have larger geographical occurrence from Palmer Archipelago to Kerguelen. The least elongated means the highest otolith, which reflects the highest body of Ps. georgianus, which help this species to stay on the shelf during swimming. High body gives less drifting during swimming in the currents. Evolution of otolith shape is linked with a body shape to decrease resistance and achieve high speed of swimming. During development, Ps. georgianus use different currents and countercurrents to catch different krill stages. System of current is natural environment of life ofPs. georgianus.

Economic Competition for High Profits from Antarctic Living Resources in Their Protection Area

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.

Fish diversity and molecular taxonomy in the Prydz Bay during the 29th CHINARE

In 2013, the 29th Chinese National Antarctic Research Expedition（CHINARE） prospected the Prydz Bay on the Antarctic continental shelf, and the Chinese R/V Xuelong icebreaker sampled all of the examined locations. The nature of Antarctic fish diversity in the high-latitude Prydz Bay is virtually unknown, and the accuracy of relevant estimates has not been established. Thus, it is necessary to evaluate this diversity and propose protective measures. In total, ninety-nine specimens were collected from various locations. To overcome uncertainties associated with identifying species based on morphology, DNA barcoding（COI gene） was employed to reconstruct phylogenetic relationships with delimited references from NCBI. Twenty-two species representing six families were unambiguously identified from a neighbor-joining（NJ） tree and barcoding gaps. With the morphological identification, thirteen species were identified correctly, five species were identified correctly at the genus level, and four species were identified at the close sister species level. Notothenioid dominance was not evident in the Prydz Bay, in contrast to other published studies. The low species diversity and catch biomass during this CHINARE were severely constrained by limited fishing methods and localized sites, which led to biased underestimation. Our analyses indicate that DNA barcoding is an effective tool for the identification of fish species in the Prydz Bay. The identification and distribution of Antarctic fish should be an integral component of understanding Antarctic fish biodiversity and biogeography, and large-scale studies are necessary for the further taxonomic identification of Antarctic fish.