CCAMLR

Capture statistic analyses from the different regions of Chile where fishery of patagonian toothfish (Bacalao de profundidad), Dissostichus eleginoides, has been developed are based in statistics published by the SERNAP (National Fishery Service). It shows that activity has lasted few years in each geographic region considered. As captures have decreased in the northern zone, the artisanal fleet has migrated towards south, concentrating actually in the X Region of Chile and we attract attention that, during the last years, a worrying by catch of factory boulterer vessels dedicated to the austral hake ( Merluccius australis ) have increased its captures in the most southern Region.

Dissostichus eleginoides is becoming an increasingly important species in the fisheries of the Southern Ocean. In Division 58.5.1, a directed trawl fishery has been in operation since 1984/85 and has expanded in the deep western sector of the Kerguelen shelf. This fishery harvests the sub-adult/adult part of the stock. Fishing effort and corresponding catches are very variable from one year to another and highly dependent on the harvestable resources of C. gunnari. Vital biological information for population dynamics, as well as demographic structures and trends observed in an abundance index are provided. Prospects for exploitation are discussed with respect to the development of fishing methods.

Feeding patterns of four Nototheniid, three Channichthyiid and two Bathydraconiid species were investigated and their daily diets were assessed from data obtained at a day-long station carded out in the Cosmonauts Sea (67°50 S - 41°25 E) in March 1988.
The type of food consumed by Chaenodraco wilsoni and Trematomus eulepidotus indicates that they are plankton-eaters as their diet comprised mainly of Euphausiids; T. centronotus is a benthophage feeding mainly on Gammarids and Polychaetas, T. hansoni is euriphagous while Dissostichus mawsoni, Cygnodraco mawsoni, Gymnodraco acuticeps, Chionodraco hamatus and Cryodraco antarcticus are predators which feed on juvenile Nototheniids and Myctophids.
Daily diet volumes of the species studied varied from 1 to 4% of their body weight while annual volumes ranged from 3 to 9 times their body weight. Mean annual diet volume of antarctic fish species was around 5 times their body weight.

Sexual maturation in the Mackerel Icefish, Champsocephalus gunnari, was studied by macroscopic examination of gonads. Evidence in support of the hypothesis that a proportion of mature fish fail to spawn was obtained. Histological examination of ovaries indicates that some ova were undergoing regression and resorption at least two months prior to the normal spawning date. It is concluded that the underlying cause is probably due to a shortage of krill, an important dietary item for Champsocephalus gunnari.

The results are presented of studying icefish vertical migration based on the data of R/V cruises during the seasons of 1982-83, 1983-84 and 1986-87, when this species was highly abundant on the South Georgia shelf. It is revealed that at day time the fish distributes near the bottom and the maximum catches were available at the middle of the light hours of the day. At twilight the fish concentrations migrate into the water column and the catches greatly decrease. The direct observations of icefish vertical migrations provided by means of hydroacoustic equipment are presented.