CCAMLR Science, Vol. 7 (2000): 141

BIOLOGICAL CHARACTERISTICS OF STOCKS IN THE SOUTHERN REGION

K.-H. Kock Institut fur Seefischerei Bundesforschungsanstalt fiir Fischerei Palmaille 9, D-22767 Hamburg, Germany

C.D. Jones National Oceanic and Atmospheric Administration National Marine Fisheries Service US Antarctic Marine Living Resources Program PO Box 271, La Jolla, Ca. 92038, USA

S. Wilhelms HelenenstraBe 16 D-22765 Hamburg, Germany

Abstract

Commercial exploitation of finfish in the southern Scotia Arc took place from 1977/78 to 1989/90, and was in its heyday from 1977/78 to 1981/82. Except for Elephant Island, the state of fish stocks of the southern Scotia Arc region has been accorded little attention until 1998, despite substantial catches in the first four years of the fishery and ample opportunity to sample these catches. The only scientific surveys of these stocks during these years were conducted by Germany in 1985, and by Spain in 1987 and 1991. More recently, the US Antarctic Marine Living Resources (US AMLR) Program carried out two extensive surveys around Elephant Island and the lower Shetland Islands in March 1998 and around the in March 1999. In this paper, the authors present new data on composition, species groups, length compositions, length-weight relationships, length at sexual maturity and length at first spawning, gonadosomatic indices and oocyte diameter.

Lesser Antarctic or peri-Antarctic species predominated in the fish fauna. Species groups differed by up to 55-60% from one shelf area to the other, mostly due to differences in the abundance of the predominant species on each shelf area and the increase in the number of high-Antarctic species in the South Orkney Islands. Length compositions and the proportion of large (= old) specimens in the populations provided no evidence of illegal fishing since the closure of the region some 10 years ago. Differences in length-weight relationships between areas were primarily due to differences in length compositions of the fish caught, but did not suggest geographical differences in length-to-weight growth. Differences in estimates of length at sexual maturity and length at first spawning indicate that in some species final maturation of the gonads takes one year or more, whereas in others gonad maturation was completed within one season. Length at sexual maturity and length at first spawning in Chan~psoceplzaltisgtinnari was one year later on the southerly grounds than at South Georgia. The distribution of gonadosomatic indices in March suggested that Lepidonotothen squainifrons was spawning while Trelnatomt~shansotzi was already coming to the end of its reproductive season. rastvospinostis and Trenzatomzis eulepidottis were close to spawning. Other species, such as Notothenin rossii and Pseudochaetzichtlzys georgiantis, at least one to two months later than at South Georgia. Channichthyids (except C. gt~nnari), rossii and Nototlzenia coriiceps have egg diameters of 4.3-5.2 mm at spawning. The Trematoinus species investigated have egg diameters of 2.8-3.2 mm while in species of the genera Gobionototl~en and Lepidonotothen, egg diameters rarely exceeded 2.0 mm. Measurements of oocyte diameters confirmed the findings on spawning time estimated from gonadosomatic indices.

Resume

L'exploitation commercial du poisson dans la region de l'arc Scotia du Sud qui a eu lieu de 1977/78 a 1989/90 a connu ses plus beaux jours de 1977/78 a 1981/82. L'etat des stocks de poissons de la region de l'arc Scotia du Sud, B l'exceptioi~de ceux de l'ile ~l+hant,n'a guere attire l'attention jusqu'en 1998, malgre les grosses captures des quatre Kock et al.

premieres annees de la pscherie et les nombreuses occasions d'echantillonner ces captures. Les seules campagnes d'evaluation scientifiques menees sur ces stocks 21 cette epoque l'ont et6 par I'Allemagne en 1985 et par 1'Espagne en 1987 et 1991. Plus tard, le programme des ressources marines vivantes des ~tats-~nis(US AMLR) a entrepris deux grandes campagnes d'evaluation autour de l'ile ~le~hantet au sud des iles Shetland du Sud en mars 1998 et autour des Orcades du Sud en mars 1999. Dans ce docun~ent,les auteurs presentent de nouvelles donnees sur la composition des especes, les groupes d'especes, la composition en longueurs, les rapports longueur-poids, la longueur a la maturite sexuelle et a la premiere reproduction, les indices gonadosomatiques et le diamPtre de l'ovocyte.

La faune ichtyologique comprend moins d'especes antarctiques ou subantarctiques. Les groupes d'especes diffPrent jusqu'a 55-60% d'un secteur du plateau a un autre, en raison principalement des differences d'abondance des especes prkdominantes dans chacune des regions du plateau et de l'augmentation du nombre dlespPces de hautes latitudes de I'Antarctique dans les Orcades du Sud. La composition en longueur et la proportion de specimens de grande taille (C.-&-d.2ges) dans les populations ne laissent pas a penser qu'il y ait eu de psche illegale depuis la fermeture de la region il y a une dizaine d'annees. Les differences dans les rapports longueur-poids d'une region a une autre s'expliquent principalement par des differences de composition en longueurs des poissons captures, et non pas des differences geographiques de la croissance en longueur selon le poids. Les differences dans les estimations de la longueur a la maturite sexuelle et a la premiere reproduction indiquent que chez certaines especes la maturation finale des gonades se deroule sur un an ou plus, alors que chez d'autres especes, elle se produit en une saison. La longueur ?ila maturite sexuelle et 2 la premiere reproduction de gunnari est atteinte un an plus tard dans les r6gions les plus au sud qu'en Georgie du Sud. La distribution des indices gonadosomatiques en mars laisse entendre qu'alors que Lepidonotothen squamifrons Ptait en periode de ponte, Trenzatonzus hansoni terminait sa saison de reproduction. Chionodraco rastrospinostls et Trematomus et~lepidottlsetaient sur le point de se reproduire. D'autres especes, telles que Notothenia rossii et Pseudochaenichthys georgianus, se reproduisent au minimum un ou deux mois plus tard qu'en Georgie du Sud. Les Channichthyides (B l'exception de C. gunnari), Nofothe7zia rossii et Notothenia roriiceps pondent des eufs d'un diametre de 4,3-5,2 mm. Les espPces Ptudikes de Trernatom~ls produisent des ceufs d'un diametre de 2,8-3,2 mm alors que chez les espkces du genre Gobionotothen et Lepidonofothen, les eufs depassent rarement 2,O mm de diametre. Les mesures du diametre des ovocytes confirment les estimations de l'epoque de la reproduction etablies ?ipartir des indices gonadosomatiques.

KOMM~PY~CKM~npOMbICen pb16b1 B H)xHo~~YBCTB AyrH CKOTHSIBenCR C 1977/78 IIO 1989/90 rr. M AocTMr pacnBeTa B 1977/78-1981182 rr. 3a McKnIoveHHeM o-~a3ne@a~~, COCTOSIHHH) pb16~b1x3anaco~ B IOXHOE Yacm AyrH CKOTHSIAO l998 r. ygenxnocb HeAOCTaTOqHO BHklMaHMSI, HeCMOTPR Ha 3~aYEI~eJlb~b1%BbIJIOB B IIepBbIe 4 rOAa IIpOMbICna H IIpeKpaCHyIO BO3MOWHOCTb An2 0~60pa06pa7rlo~ M3 3TMX YJIOBOB. B TeveHHe 3~oroneptiona ~ay~~o-1.rccnenosa~enbc~tiecaeMm sanaco~6b1n~ npoBeneab1 TonbKo rep~a~aeilB 1985 r. H Mcna~kieiiB 1987 11 1991 rr. Hena~~oB paMKax ~M~~HK~HCKO~~~PO~P~MM~I M3YYeHAR MOPCKBX XMBbIX PeCypCOB AHT~PKTMKH(US AMLR) 6b1nEI IIpOBeAeHbI 2 KpyIIHbIe C'beMKM: B pafi0~e0-Ba ~JI~@~HTB HMXH~~ yaCTB K)>t(Hbl~LU~TJI~H~~CKHX 0-BOB B MapTe 1998 r. B BOKPYr ~XH~IXOPKH~I%CKI~X 0-BOB B MapTe 1999 r. B 3~0aCTaTbe aBTOPb1 IIpeACTaBJISlWT HOBbIe HaHHbIe IlO BMAOBOMY COCTaBy, BBAOBMM rpyIIIIaM, pa3MepHOMy COCTaBy, OTHOLUeHHK) AJIAHa-BeC, AnPIHe IlpA AOCTMXeHHM IIOJIOB03peJIOCTH H IIpH IIepBOM HepeCTe, rOHaAOCOMaTHYeCKHM HHAeKCaM M IlO AllaMeTpy OOqATOB.

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QOCTHXeHHH HOnOB03penOCTH H npll IIepBOM HepeCTe rOBOpHT 0 TOM, YTO Y HeKOTOPblX BIlnOB OKOHYaTenbHOe C03PeBaHAe rOHaR 3aHKMaeT He MeHbLIle rona, B TO BpeMR KaK y npyrnx BAAOB cospe~a~~eroHan npoMcxonmT 3a OAMH ce30~.AnllHa C/zarnpsocephalus gurzrzari npn RocmxeHaH nono~o3penoc~nH npn nepBoM HepecTe Ha 6onee IOXH~IX yyacmax oTcTaBana Ha roA no cpasHeHmo c OXH HOW reoprneii. Pacnpe~ene~~e rOHaAOCoMaTHYeCKHX IlHAeKCOB B MapTe yKa3bIBaeT Ha HepeCT Lepidorzototlzerz squamijkons, HO B TO me BpeMx Ha sa~eprue~aepenpoAyKTHBHoro ceso~ay Trematomus /zarzsoni. Chioriodraco rastr-ospinosus H Trematornus eulepidotus 6b1na B npeRHepecToBoM COCTORHHM.Apyrne BHA~I,Tame KaK Notothenia rossii n Pseudochnerzichthys georgiarzus, HepecTtInHcb no ~paii~eiiMepe Ha 1-2 Mecxqa no3me, qeM y tOx~oii reorp~u.GM~M~T~ HKP~I npn HepecTe y Geno~pos~b~xp616 (sa mcKnmqeHneM C. gunnari), Nototherzin rossii M Notofherzia coriiceps 6bm 4.3-5.2 MM, y M3YYaBUIMXCR BMAOB Trematornus - 2.8-3.2 MM,a y POAOB Gobiorzototlzen M Lepidorzotothen OH peAKo IIpeBbILLIaJI 2.0 MM. M~M~P~HMR+Ql?aMeTpOB OOqMTOB HOATBePAHnM BbIBOnbI 0 BpeMeHM HepeCTa no roHaAoCoMaTMYeCKHM MHAeKCaM.

Resumen

La explotacion comercial de peces en la zona sur del arco de Escocia se llevo a cabo de 1977/78 a 1989/90, y tuvo su auge en el periodo de 1977/78 a 1981/82. Exceptuando 10s stocks de isla Elefante, hasta 1998 poco se habia estudiado el estado de las poblaciones de peces de la region sur del arco de Escocia, a pesar de que durante 10s primeros cuatro afios de la pesqueria comercial se extrajeron capturas substanciales y hubo amplia oportunidad de muestrear dichas capturas. En esos afios, Alemania (en 1985) y Espafia (en 1987 y 1991) fueron 10s unicos paises que llevaron a cabo prospecciones cientificas de estas poblaciones. Mas recientemente, el programa de 10s recursos vivos marinos antarticos de Estados Unidos (AMLR) llevo a cabo dos extensas prospecciones alrededor de la isla Elefante y a1 sur de las islas Shetland del Sur en marzo de 1998, y alrededor de las islas Orcadas del Sur en marzo de 1999. En este documento, 10s autores presentan nueva informacion sobre la composicion por especie, grupos de especies, composicion por talla, relacion talla/peso, talla de madurez sexual y del primer desove, indices gonadosomaticos y diametro de 10s oocitos.

En la fauna ictica predominaron las especies del oeste de la Antartida o peri-antarticas. La diferencia entre 10s grupos de especies de distintas zonas de la plataforma fue de un 55 a 60%, debido en su mayor parte a diferencias en la abundancia de las especies predominantes en cada zona de la plataforma y a1 aumento del numero de especie de latitudes altas en las islas Orcadas del Sur. El examen de la composici6n por tallas y de la proporcion de ejemplares de peces de gran tamafio (es decir, viejos) en las poblaciones de estudio no mostro evidencia de que se haya realizado la pesca ilegal desde que se impuso la veda de la pesca hace unos 10 aAos. Las diferencias entre la relacion talla/peso observadas en cada area se deben en su mayor parte a las diferencias en la composicion por talla de 10s peces capturados, pero no hay indicaciones de que existan diferencias geograficas en relacion a la tasa de crecimiento talla/peso. Las diferencias en las estimaciones de la talla de madurez sexual y del primer desove indican que en algunos peces la maduracion completa de las gonadas toma por lo menos un afio, mientras que en otros el proceso de maduracion habria ocurrido dentro en una temporada. La talla de madurez sexual y del primer desove de Champsocephalus gunnari de las regiones australes se alcanzo un afio despues que en Georgia del Sur. La distribucion de 10s indices gonadosomaticos indica que en marzo la especie Lepidonotothen sqzlarnifrons estaba desoval~domientras que Tre~nafomushansoni estaba terminando su temporada de reproduccidn y Chionodraco rasfrospinoszls y Trematomus eulepidotus estaban por comenzar el desove. Otras especies, como Nototlzenia rossii y Pseudochaenichthys georgianus, desovan por lo menos uno o dos meses despues que en Georgia del Sur. El diametro de 10s huevos de 10s caenictidos (except0 C. gunnari), Notothenia vossii y Notoflzetzin coriiceps en el desove es de 4,3 a 5,2 mm. El diametro de 10s huevos de la especie Trernatoinus estudiada es de 2,8 a 3,2 mm, mientras que para 10s generos Gobionotothen y Lepidonotothen este rara vez excede de 2,O mm. La medici6n del diametro de 10s oocitos confirm6 las observaciones sobre la epoca de desove estimada a partir de 10s indices gonadosomaticos.

Keywords: trawl surveys, finfish, species and length composition, length-weight relationship, maturity, spawning, gonadosomatic indices, Scotia Arc, CCAMLR Kock et al.

INTRODUCTION After having focused on South Georgia (Everson et al., 1991, 1992, 1994; Kock, 1978, 1979; Kock et Antarctic waters have been commercially al., 1994) and Elephant Island (Kock, 1982, 1986, exploited by trawl fishing since the second half of 1989a, 1998) from the late 1970s to the first half the 1960s, principally by fleets from the ex-Soviet of the 1990s, research was intensified again in the Union and other former Eastern Bloc countries. The southern Scotia Arc from 1996 onwards (Kock, fishery in the sector began on the 1998). A bottom trawl survey around Elephant stock of Notothenin rossii at South Georgia. The Island and the lower to stock was depleted within two seasons after about Low Island in the west was conducted in 1998. 500 000 tonnes had been taken (CCAMLR, 1990a). Thirty-seven hauls were carried out around After some years of low fishing effort, the fishery Elephant Island and 35 hauls around the South switched to the icefish Charnpsocephalus gunnari Shetland Islands (Jones et al., 1998a, 1998b), and later the nototheniid Patagonotothen gtintheri in addition to the 182 hauls conducted around around Shag Rocks, with some of the by-catch Elephant Island from 1978 to 1996 (Kock, 1998). In species, such as Gobionotothen gibberifions and 1999,64 hauls were used to study the distribution, Psezldochaenichthys geougianus, being taken in abundance and biological features of fish stocks substantial numbers in single years. The fishery around the South Orkney Islands in more detail was extended to the island shelves of the southern (Jones et al., 2000). In this study, the authors report Scotia Arc from 1977/78 onwards. Myctophids new findings on the biology of stocks (mostly Electrons carlsbergi) came into the fishery in the southern Scotia Arc. for some years in the late 1980s. Since the early 1990s, the fishery was almost exclusively a longline MATERIAL AND METHODS fishery which targeted Patagonian toothfish (Dissosticht~seleginoides). The South Orkney Islands, Elephant Island (and the much smaller Clarence, Elephant Island and the lower South Shetland Aspland, Eadie and O'Brien Islands) form the Islands were closed to commercial finfishing after northernmost part of the South Shetland Island the 1989/90 season (CCAMLR, 1990b). group. They are separated from the lower South Shetland Islands by a narrow trench which is Biological investigations of fish stocks in the in some places slightly more than 500 m deep. Atlantic Ocean sector of the The South Orkney Islands are located some concentrated mostly on commercially exploited 150 n miles to the east of Elephant Island. The shelf fish stocks around South Georgia (Subarea 48.3) areas of both island groups are separated by waters (Permitin and Silyanova, 1971; Permitin and 2 000-3 000 m deep. The study area is shown in Tarverdiyeva, 1972; Kock, 1986; Agnew and Figures la-lc. Moreno, 1992; Moreno et al., 1996; Agnew et al., 1998) and to some extent around Elephant Island This analysis was based on the catch composition (eastern part of Subarea 48.1) (Kock, 1986, 1989a, of 37 bottom trawl hauls from Elephant Island 1998). Information from other fishing grounds (Figure la) and 35 hauls from the South Shetland remained sparse (Sosinski, 1985; Kock, 1986; Islands, both conducted in March 1998 (Figure lb), Balguerias and Quintero, 1989; Balguerias, 1991) and 64 hauls from the South Orkney Islands despite substantial commercial activities in these (Figure 1c) carried out in March 1999. Details on areas from 1977/78 onwards. The South Sandwich the gear used, the distribution of hauls and the Islands (Subarea 48.4) have only been investigated sampling strategy were provided in Jones et al. scientifically by a limited number of bottom trawl (1998b) for Elephant Island and the South Shetland and bentho-pelagic trawl hauls in 1976 (Kock, Islands, and Jones et al. (2000) for the South Orkney Islands. Net selectivity was negligible due to the 1978), 1987 (Balguerias and Quintero, 1989) and use of small-meshed (20 mm) liners. All sampling some longlining in 1993 (Ashford et al., 1994). The stations (Figures la-lc) followed a stratified random South Orkney Islands (Subarea 48.2) were surveyed survey design. However, they were restricted by bottom trawl in 1985 (Kock, 1986), semi-pelagic to areas where trawling conditions seemed to trawl in 1987 (Balguerias and Quintero, 1989) and be moderate or good following acoustic bottom bottom trawl again in 1991 (Balguerias, 1991) after reconnaissance. Fishing was conducted only during some limited research had been initially conducted daylight hours (i.e. between 0600 and 1900 hours in 1976 and 1978 (Kock, 1978, 1979). The South local time). Shetland Islands (western part of Subarea 48.1) were studied incompletely by bottom trawl in 1976 Catches up to 500 kg were analysed in toto and (Kock, 1978) and in 1987 by a survey using a semi- sorted and identified to species level. A subsample pelagic trawl (Balguerias and Quintero, 1989). of at least 500 kg was taken from the comparatively Biological characteristics ofAntarctic fish stocks few larger samples of 0.6 to 2.5 tonnes. Total length cluster linkage methods revealed no significant of all individuals was measured to the nearest differences from the results of the methods used. centimetre below. Total weight was determined to The species mostly responsible for the observed the nearest 10 g in specimens of >l00 g and to patterns of classification were identified in a the nearest gram in individuals of

However, even more than 5O0/0 of the fish larger years. The area with the largest influence of than 4045 cm had gonads in resting stage in the water appeared to be the South months prior to spawning. Orkney Islands which host the largest proportion of high-Antarctic fish species both in terms of numbers of species and in terms of individuals. Gonad Cycle and Oocyte Diameter The benthic (= demersal) fish fauna of the shelf Gonad weights and oocyte diameters were and upper slope areas of the whole Scotia Arc, measured mostly around the South Orkney Islands including South Georgia and Shag Rocks, has been in March 1999 (Table 4). The material for the other extensively studied by trawl surveys since the mid- two areas was much scarcer due to the more limited 1960s. The fish fauna was well known in terms of time available for sampling. Oocyte diameter was its composition and a number of its biological determined in 19 specimens of 6 species from features around South Georgia and Elephant Elephant Island and the South Shetland Islands, Island (Kock, 1992, for review, 1998; Tiedtke and and in 124 specimens of 14 species from the South Kock, 1989) but less studied at the South Shetland Orkney Islands (Table 5). Islands and the South Orkney Islands.

Only two species (L. squa~nifronsand Trematomus The fauna was much less known hansoni) were spawning in March or were than the demersal ichthyofauna. It has been approaching the end of their spawning season intensively investigated around South Georgia by (T. lzansoni). Three other species (C. rastrospinosus, Russian researchers in the second half of the 1980s T. eulepidotus and probably L. nudifrons) were either (Frolkina et al., 1998). However, little seemed to close to spawning (Elephant Island, South Shetland have been published in addition to a range of papers Islands) or began to spawn within the next two to on biological aspects of some commercially four weeks (South Orkney Islands). All other interesting myctophids, such as E. carlsbevgi (Kozlov species were at least four to eight weeks (C. acevatus, et al., 1990; Mazhirina, 1990; Gerasimova, 1990; C. gunnari, P. georgianus, N. coriiceps and N. vossii) Filin et al., 1990). The pelagic fish fauna of the from spawning or were even several months southern Scotia Arc remained, with a few exceptions from spawning (Trematomus newnesi, L. larseni, among myctophids, poorly known. G. gibberifions and Trematomtis bernacchii). Although quantitative data were more limited from the The demersal fish fauna of the whole Scotia Elephant Island-lower South Shetland Islands Arc is predominated by lesser Antarctic or peri- region, spawning appeared to start there at least Antarctic species, sucl~as G. gibberzfrons, C. acevatus two to four weeks earlier than at the South Orkney or C. gunnari. The composition of the fish fauna Islands. The wider range of gonad weights in was similar in all shelf regions, although with some C. aceratus may indicate that the species spawned peculiarities in each of the areas. Due to the virtual over a range of two to three months. Other species, absence of high-Antarctic species at South Georgia, such as N. coriiceps, apparently have a more limited the fish fauna there was somewhat impoverished spawning season of only four to six weeks. compared to the southern Scotia Arc. This was particularly the case for species of the The range of egg diameters appeared to be low Trematomus (only 7'. hansoni present), the limited in most species with the exception of C. aceratus number of channichthyids present (only three and possibly C. gunnari (Table 5). This suggests species and a fourth, Champsocephnlus esox, De Witt that many species spawned within a comparatively et al., 1976, as a vagrant from the southern short period of four to six weeks. Patagonian shelf), and artedidraconids (one species) and bathydraconids (two species). Some Patagonian species which were absent from the more southerly DISCUSSION grounds, however, such as P. guntheri or C. esox were observed. A further peculiarity was the The southern Scotia Arc region is influenced by presence of the bathydraconid Psilodraco breviceps two hydrograplucal regimes: Antarctic Circumpolar and the artedidraconid Artedidraco mirus which Water in the north and water from the Weddell Sea were endemic to the shelf of South Georgia. in the south which mix in the area. The influence of Weddell Sea water decreases towards the north The southern Scotia Arc has a richer species although waters of Weddell Sea origin are still inventory than South Georgia due to the occurrence being found on the South Georgia shelf in some of a substantial number of high-Antarctic species. Kock et a1

These high-Antarctic species reach their northern- area from the late 1970s to the early 1980s. This most distribution in the southern Scotia Arc. This pattern of distribution along a vertical axis (depth) referred in particular to members of the genus appeared to be similar in some areas around the Trematomus, to channichthyids, and to members lower South Shetland lslands and the South of tl~eartedidraconid genus Pogonophryne. High- Orkney Islands. A detailed analysis of these fish Antarctic species were confined to the southern associations is still pending. Scotia Arc with a few exceptions, where single specimens of some high-Antarctic species had been Limited studies have so far been conducted in swept north on to the southernmost part of the waters of less than 50 m depth due to problems shelf of South Georgia (Kock and Stransky, 2000). encountered in trawling with larger vessels in High-Antarctic species made up a considerable these shallows. Everson (1970) found N. coriiceps proportion of the species inventory in the to be very abundant in shallow waters off southern Scotia Arc. However with the exception Signy Island (South Orkney Islands). Juveniles of of C. rastrospinosus, they contributed little to the G. gibberifvons belonging to age classes 0-2 (Figure 6) abundance of the demersal fish fauna. were caught in some numbers in waters of 20-30 m off the southwest coast of Elephant Island by a The composition of the demersal fish fauna was 3 m beam trawl. Early juveniles of other species, similar in all three shelf areas of the southern Scotia such as P. georgia~zus or C. rastrospinosus, were Arc. Causes for changes in the composition of the known to lead a pelagic mode of life, and were fish fauna between the three shelf regions were caught as single specimens, if at all, during bottom primarily due to: trawling. For a substantial number of species, in particular those living in high-Antarctic waters, (i) changes in the abundance of the most the early juvenile stages were still unknown. dominant lesser Antarctic species from one Studies at Admiralty Bay and Potter Cove (King shelf region to the other; George Island, South Shetland Islands) showed that N. coriiceps, N. rossii, G. gibberifrons and (ii) changes in the abundance of C. rastrospinosus Harpagifer antarcticz~s were abundant nearshore. (3.9% of the abundance of all species at Some information was made available on tissue Elephant Island, 8.3% at the South Shetland metabolism, and carbon dioxide levels Islands and 15.1°/0 at the South Orkney in Antarctic fish (Bacila et al., 1989; Fanta et al., Islands); and 1989) and the age, growth and feeding of some nototheniids from nearshore trammel net catches (iii) differences in the abundance of high-Antarctic (Barrera-Oroand Casaux, 1992,1996; Casaux et al., species which made up 3.6% of all species at 1990; Linkowski and Zukowski, 1980; Linkowski Elephant Island, 10.1% at the South Shetland et al., 1983; Fanta et al., 1994). However these Islands and 17.4O/0 at the South Orkney investigations still stemmed from very limited Islands. areas. Larger-scale studies on the distribution, abundance and biology of fish in inshore waters Some separation by depth was also apparent have yet to be conducted. between lesser Antarctic and high-Antarctic species. Most of the lesser Antarctic species had their The length-frequency distributions showed maximum abundance at less than 250 m. The that maximum length of the most abundant high-Antarctic species mostly occurred below species was lower on all three southerly grounds 250 m or even deeper (Tiedtke and Kock, 1989; compared to those from South Georgia prior Kock and Stransky, 2000). It is impossible to to commercial exploitation. Maximum observed conduct a detailed analysis of each demersal fish length in G. gibberifvons, C. aceratus and C. gunnari group (associations) on each of the shelf areas at South Georgia, for example, were 52, 75 and within the remit of this paper. A detailed description 62 cm while they were 47/70 and 58 cm further to of the different fish groups, their shifts in the south. The shape of the length compositions composition with depth, and their change in and the proportion of large (= old) specimens in the abundance with past fishing pressure has been catches suggested that no substantial illegal fishing provided only for Elephant Island down to 500 m had taken place since the closure of the areas for depth (Tiedtke and Kock, 1989; Kock and Stransky, finfishing in 1989/90 (CCAMLR, 1990b). 2000). Five fish groups, which overlapped to some extent in their bathymetric distribution, were Length-weight relationships were similar in present at Elephant Island. G. gibberifvons became all three areas. They were also not very different the most abundant fish species after C. gunlzari and between years as shown in comparison to data N. rossii had been depleted by intensive fishing the provided by Kock (1986), Kock et al., (1985) and Biological characteristics of Antarctic fish stocks

Balguerias and Quintero (1989). Such differences Length at sexual maturity and length at first as were observed in the length-weight relationships spawning were reached in males at a lower length were probably mostly due to differences in the than in females. However it was unclear from length range sampled in the three areas and to the growth studies in fish populations at South inhomogeneity of the sampling rather than a result Georgia if males generally remained smaller than of substantial differences between individual areas females. Possible differences in growth between themselves. However, more systematic sampling, females and males varied considerably between such as that conducted at the South Orkney Islands species. L, in males of N. rossii at South Georgia in March 1999, when five specimens per sex of each and Elephant Island and males of C. aceratus in the 1 cm length class were sampled over the whole Scotia Arc region was 10 and 17 cm lower than length range of a given species, will help us to in females respectively (Sherbich, 1976; Freytag, reveal in the future if actual differences in 1980; Gubsch, 1982; Jones et al., 199813). In contrast, length-weight relationships existed between areas. G. gibbevzfrons, L. larseni and L. sqt~awzzfronsappeared to have similar growth curves in males and females The only species spawning in March were (Shust and Pinskaya, 1978). L. squainifrons and T. haiisoizi. Two other species, C. rastvospinosus and T. eulepidotus, were close (two The attainment of length at sexual maturity and to four weeks) to spawning. Spawning in N. rossii of length at first spawning appeared to take place a and C. acevatus probably occurred about four to six year later in C. gunnavi in the southern Scotia Arc weeks later than at South Georgia. Spawning time than at South Georgia where the species was in C. and P. was apparently gunnavi geovgiantls already mature towards the end of its third year two to three months later than at South Georgia of life (Kock and Everson, 1997). Length at first and about one month later at the South Orkney spawning should be in the order of 32 to 34 cm at Islands than at Elephant Island. N. coriiceps spawns the South Orkney Islands, Elephant Island and the in May-June. Spawning of T. newnesi appeared to South Shetland Islands (Kock, 1989a). This was, take place in June-July. L. larseni and G. gibbevifrons however, not obvious from our data from the reproduced in July-September. Spawning in South Orkney Islands. The proportion of females G. gibberifuoizs, L. lavseni, L. squ~ainifroizs and caught in the critical length range of 27-32 cm, in N. coriiceps seemed to take place at approximately the same time in all three areas. which the first mature specimens are usually observed, was very small. This probably led to the Length at first spawning was apparently reached underestimate of-^^, of 29.5 cm. L,, is likely to within one season in females of G. gibbevifuoizs, change to 32-34 cm, similar to that in males, when L. lavseni, T. eulepidotus and C. rastvospinos~~s. more fish of this length range are studied on future Maturation may take a year in L. sqz~ainif?ons, cruises. P. geovgianus, C. guiznari and N. rossii. Females of C. aceratz~s may take more than a year from The proportion of C. gutznari individuals which attainment of sexual maturity to first spawning. were sexually mature but whose gonads were in the resting stage (stage 2) was almost 50% at Growth curves exist for a number of species at Elephant Island. The proportion was much smaller South Georgia (Sherbich, 1976; Shust and Pinskaya, in the other two areas, which suggested a much 1978; Freytag, 1980; Kock, 1981; Frolkina and higher proportion of fish spawning in these areas. Dorovskikh, 1989) and around Kerguelen (Duhamel, A substantial proportion of fish with resting 1987). However, growth studies from areas to gonads in the pre-spawning period is also well the south of South Georgia are scarce. The only known in the population at South Georgia, albeit published growth curves for the more southerly with large variations from year to year (Kock, grounds are for N. rossii, and compare the two 1989b; Everson et al., 1996). Previous investigations stocks at South Georgia and Elephant Island (Kock, 1981) suggested that the populations off (Freytag, 1980), N. coviiceps and N. rossii from Elephant Island and around the South Shetland Admiralty Bay and Potter Cove (King George Islands were separated from each other with Island) (Linkowski and Zukowski, 1980; Barrera- little (if any) exchange. However an alternative Oro and Casaux, 1992, 1996), and N. coriiceps at interpretation that could not be ruled out was that Signy Island (Everson, 1970). Growth of fish C. gunnavi in the Elephant Island-South Shetland species is apparently slower in the southern Scotia Islands area formed only one population with the Arc than at South Georgia and fish attain a lower sexually mature but non-spawning part of the L, than around South Georgia. More detailed population mostly present in the Elephant Island growth studies of different species from these areas area and the pre-spawning fish mostly found are urgently required. further to the southwest around the South Shetland Islands. Both areas are only separated by narrow from a bottom trawl haul in the Weddell Sea, channels of depths of more than 400 to 500 m, and assumed to be T. eulepidotus, was 4.4 mm which could probably be crossed by mobile fish (Riehl and Ekau, 1990). Surface structures compared species such as C. gunnari. A more integrated in eggs from the two areas were found to be survey spanning from Shag Rocks and South very similar. This suggests that the batch of eggs Georgia to the South Shetland Islands should help collected in the Weddell Sea did, in fact, stem from to clarify the problem of stock structure in C. gunnari T. eulepidotus. Fecundity in the Weddell Sea should in the future. be much lower, given the much larger size of eggs at spawning. Further studies on the fecundity of The gonadosomatic index (GSI) of all species T. eulepidotus will follow. investigated, except one, was likely to be at least 20-25 at spawning. The only exception appeared to be L. squamifvons (Silyanova, 1981): we found CONCLUSION either spent specimens in maturity stage 5/2 or specimens in stage 3, but no specimens in actual The two cruises in 1998 and 1999 have contributed spawning condition (stage4). The GSI in specimens considerably to improving our knowledge on basic of stage 3 was about 10. Egg size was 0.9-1.0 mm. biological parameters of demersal fish species in Given that egg size was about 1.2-1.4 mm at the southern Scotia Arc. This is particularly the spawning, it seems unlikely that the GSI would case with regard to aspects such as distribution, increase to more than about 15 during spawning. abundance, community structure and reproduction Spawning seemed to occur mostly in February- of the abundant fish stocks. However gaps in our March, which is later than indicated by Silyanova knowledge for some of the subareas are still (1981), who suggested that L. squamifuons spawned substantial. Age and growth studies remain a in spring-early summer. major gap in our knowledge. Furthermore, studies between late autumn and early spring are urgently Many notothenioids in the southern Scotia needed so that food and energy budgets for the Arc appear to spawn in autumn-winter (Kock entire year can be compiled. Emphasis should also and Kellermann, 1991). Only few species, such as be placed on studies on the macro-scale distribution, , T. hansoni and L. squamifuons, abundance and biology of inshore fish populations. spawn in late spring-summer. The range of egg diameters measured seems to be low in most species. This suggests that the spawning season ACKNOWLEDGEMENT is comparatively short in most species except in C. aceratus and C. gunnari. In 1986, for example, The authors are very much indebted to more than 85% of all females and 57% of the males of N. coriiceps had spawned around Elephant K. Dietrich, P. Kappes, D. Lombard, J. Popp Island between mid-May and mid-June (Kock, and D. Ramm for the extensive work which 1989a). they carried out during the two cruises. Prof. G. Duhamel's thorough review of the paper is Channichthyids with the exception of kindly acknowledged. Our thanks also go to the C. gunnari, have a rather limited range of egg master and the crew of RV Yuzhmorgeologiya for sizes: 4.4-5.3 mm. Egg sizes in C. gunnari are only their untiring support in the course of the cruises. 3.2-3.7 mm (Duhamel, 1987; Kock, 1989a). C. Stransky kindly provided the MDS plot. Nototheniids have a much wider range of egg sizes. N. rossii and N. coriiceps have egg sizes of 4.4 to 5.0 mm (Silyanova, 1981; Kock, 1989a). REFERENCES Members of the genus Trematomus, such as T. eulepidotus and T. hansoni, have egg sizes of Agnew, D.J. and C.A. Moreno. 1992. The 2.8-3.2 mm. Egg sizes of late winter spawners, 1991/92 fishery for Dissostichus eleginoides such as L. larseni and G. gibberifrons, hardly exceed in Subarea 48.3. In: Selected Scientific Papers, 1.8-2.0 mm (Silyanova, 1981; Kock, 1989a). 1992 (SC-CAMLR-SSP/9). CCAMLR, Hobart, Australia: 3148. Egg diameters seem to be similar over the distributional range of a species. A notable exception Agnew, D.J., I. Everson, G.P. Kirkwood and appears to be T. eulepidotus. Egg diameter at G.B. Parkes. 1998. Towards the development of spawning was about 2.8-3.2 mm both at Elephant a management plan for the Island and around the South Orkney Islands. (Champsocephalt~s gunnari) in Subarea 48.3. However egg diameter in a batch of eggs collected CCAMLR Science, 5: 63-77. Biological characteristics of Antarctic fish stocks

Ashford, J.R., J.P. Croxall, P.S. Rubilar and Clarke, K.R. 1993b. A method of linkmg multivariate C.A. Moreno. 1994. Seabird interactions with community structure to environmental variables. longlining operations for Dissostichus eleginoides Mar. Ecol. Prog. Ser., 92: 205-219. at the South Sandwich Islands and South Georgia. CCAMLR Science, 1: 143-153. Clarke, K.R. and R.M. Warwick. 1994. Changes in marine communities: an approach to statistical Bacila, M., R. Rosa, E. Rodrigues, P.H. Lucchiari analysis and interpretation. Plymouth, National and C.D. Rosa. 1989. Tissue metabolism of the Environmental Research Cotrncil, UK: 144 pp. icefish Chaenocephalus aceratus Lonnberg. Comp. Biochem. Physiol., 92B (2): 313-318. De Witt, H.H., J.D. McCleave and J.H. Dearborn. 1976. Ecological studies of and echino- Balguerias, E. 1991. Informe de la campaiia derms during ARA Islas Orcadas cruise 5. US Antarctic [ourn., 6: 49-53. espafiola de evaluacion de 10s stocks de peces de Orcadas del Sur ('Antartida 9101'). Document Duhamel, G. 1987. Ichthyofaune des secteurs indien WG-FSA-91/33. CCAMLR, Hobart, Australia: occidental et atlantique oriental de l'ockan 30 PP. Austral: biogeographie, cycles biologiques et dynamique des populations. Thilse de doctorat Balguerias, E. and M.E. Quintero. 1989. Informe d18tat, Universitk Pierre et Marie Curie, Paris de resultados 'Antartida 8611'. Pescas Cientificas. VI: 687 pp. Ministerio de Agricultura, Pesca y Alimentacion. Secretaria General de Pesca Maritima. lnstituto Everson, I. 1970. The population dynamics and Espaiiol de Oceanografia: 63 pp. energy budget of Notothenia neglecta Nybelin at Signy Island, South Orkney Islands. Br. Antarct. Barrera-Oro, E.R. and R.J. Casaux. 1992. Age Surv. Bull., 23: 23-50. determination of juvenile Notothenia rossii from Potter Cove, South Shetland Islands. Ant. Sci., 4 Everson, I. 1977. The living resources of the Southern (2): 131-136. Ocean. FAO GLO/SO/77/1, Rome: 156 pp.

Barrera-Oro, E.R. and R.J. Casaux. 1996. Validation Everson, I., G. Parkes, K.-H. Kock, S. Campbell, of age determination in Notothenia coriiceps, by Z. Cielniaszek and J. Szlakowski. 1991. Fish stock means of a tag-recapture experiment at Potter assessment survey in Subarea 48.3. In: Selected Cove, South Shetland Islands. Arch. Fish. Mar. Scientific Papers, 1991 (SC-CAMLR-SSPI8). Res., 43 (3): 205-216. CCAMLR, Hobart, Australia: 25-67.

Casaux, R.J., A.S. Mazotta and E.R. Barrera-Oro. Everson, I, G. Parkes, S. Campbell, K.-H. Kock, 1990. Seasonal aspects of the biology and diet J. Szlakowski, D. Cielniaszek, C. Goss and of nearshore nototheniid fish at potter Cove, S. Wilhelms. 1992. Fish stock assessment survey South Shetland Islands, Antartica. Polar Biol., 11 in Subarea 48.3. Document WG-FSA-92/17. (1): 63-72. CCAMLR, Hobart, Australia: 40 pp.

CCAMLR. 1990a. Statistical Bulletin, Vol. 1 (1970- Everson, I., G. Parkes, K.-H. Kock, C. Goss, D. Cielniaszek, J. Szlakowski, H. Daly, 1979). CCAMLR, Hobart, Australia. L. Allcock and G. Pilling. 1994. Fish stock assessment survey in Subarea 48.3. Document CCAMLR. 1990b. Report ofthe Ninth Meeting of the WG-FSA-94/18. CCAMLR, Hobart, Australia: Commission (CCAMLR-IX). CCAMLR, Hobart, Australia: 123 pp. 34 PP. Everson, I., K.-H. Kock and G. Parkes. 1996. Chiu, T.S. and D.F. Markle. 1990. Muraenolepidae. Ovarian development associated with first In: Gon, 0. and P.S. Heemstra (Eds). Fishes maturity in three Antarctic channichthyid of the Southeriz Ocean. J.L.B. Smith Institute species. J. Fish Biol., 49 (5): 1019-1026. of , Grahamstown, South Africa: 179-182. Fanta, E., P.H. Lucchiari and M. Bacila. 1989. Effects of environmental oxygen and carbon Clarke, K.R. 1993a. Non-parametric multivariate dioxide levels on the tissue oxygenation and the analysis of changes in community structure. behaviour of Antarctic fish. Comp. Biochem. Aust. J. Ecol., 18: 117-143. Physiol., 93A (4): 819-831. Kock et al.

Fanta, E., A.A. Meyer, S.R. Grotzner and 1998 US AMLR bottom trawl survey. Document M. Luvizotto. 1994. Comparative study on WC-FSA-98/17. CCAMLR, Hobart, Australia: feeding strategy and activity patterns of two 14 PP. Antarctic fish: Trematolnus newnesi Boulenger 1902 and Gobionotothelz gibberifvons (Lonnberg, Jones, C.D., K.-H. Kock and S. Wilhelms. 1998b. 1905) (Pisces, ) under different Results from the 1998 bottom trawl survey light conditions. Antarctic Rec., 38 (1): 13-29. of Elephant Island and the lower South Shetland Islands (Subarea 48.1). Document Field, J.G., K.R. Clarke and R.M. Warwick. 1982. A WG-FSA-98/15. CCAMLR, Hobart, Australia: practical strategy for analysing multispecies 31 PP. distribution patterns. Mar. Ecol. Prog. Ser., 8: 37-52. Jones, C.D., K.-H. Kock and E. Balguerias. 2000. Changes in biomass of eight species of finfish Filin, A.A., K.V. Gorchinsky and V.M. Kiseleva. around the South Orkney Islands (Subarea 48.2) 1990. Biomass of myctophids in the Atlantic from three bottom trawl surveys. CCAMLR sector of the Southern Ocean as estimated by Science, 7: 53-74. acoustic surveys. In: Selected Scientific Papers, 1990 (SC-CAMLR-SSPP). CCAMLR, Hobart, Kock, K.-H. 1978. Fischereibiologische Unter- Australia: 417431. suchungen. In: Sahrhage, D., W. Schreiber, R. Steinberg, G. Hempel (Eds). Antarktis- Freytag, G. 1980. Length, age and growth of Expedition 1975/76 der Bundesrepublik Deutsch- Notothelzia rossii marmorata Fischer 1885 in the land. Auch. FischWiss., 29 (1): 41-57. West Antarctic waters. Arch. FischWiss., 30 (1): Kock, K.-H. 1979. Fischereibiologische Unter- 39-68. suchungen an Fischen. In: Hempel, G., D. Sahrhage, W. Schreiber, R. Steinberg (Eds). Frolkina, G.A. and R.S. Dorovskikh. 1989. On Antarktis-Expedition 1977/78 der Bundesrepublik assessment of Bertalanffy growth equation . Arch. FischWiss., 30 (1): 71-84. parameters and instantaneous natural mortality rate of South Georga mackerel icefish. Ln: Selected Kock, K.-H. 1981. Fischereibiologische Unter- Scientific Papers, 1989 (SC-CAMLR-SSP/6). suchungen an drei antarktischen Fischarten: CCAMLR, Hobart, Australia: 29-36. Champsocephalus gz~nnari (Lonnberg, 1905), Ckaenocepkalus aceratus (Lonnberg, 1906) und Frolkina, G.A., M.P. Konstantinova and I.A. Trunov. Pseudochaenichthys georgianus Norman, 1937 1998. Composition and characteristics of ich- (, ). Mitt. Inst. thyofauna in pelagic waters of South Georgia Seefisch. Harnbtlrg, 32: 1-226. (Subarea 48.3). CCAMLR Science, 5: 125-164. Kock, K.-H. 1982. Fischereibiologische Unter- Gerasimova, O.V. 1990. Feeding and food in suchungen bei Elephant Island im Marz 1981. take of Electrons carlsbergi (Thing, 1932), Arch. FischWiss., 33 (1): 127-142. Myctophidae. In: Selected Scientific Papers, 1990 (SC-CAMLR-SSP/7). CCAMLR, Hobart, Kock, K.-H. 1986. The state of exploited Antarctic Australia: 411416. fish stocks in the region during SIBEX (1983-1985). Arch. FischWiss., 37 (1): 129-186. Greenstreet, S.P.R. and S.J. Hall. 1996. Fishing and the groundfish assemblage structure in the Kock, K.-H. 1989a. Reproduction in fish around north-west North Sea: an analysis of long-term Elephant Island. Arch. FischWiss., 39 (1): 171-210. and spatial trends. J. Anim. Ecol., 65: 577-598. Kock, K.-H. 1989b. Reproduction of the mackerel Gubsch, G. 1982. Zur Verbreitung und zur Biologie icefish (Champsocephalus gt~nnari) and its der Eisfische (Chaenichthyidae) im atlantischen implications for fisheries management in Sektor der Antarktis. Fischerei-Forsch., 20 (2): the Atlantic Ocean sector of the Southern 39-47. Ocean. In: Selected Scientific Papers, 1989 (SC-CAMLR-SSPI6). CCAMLR, Hobart, Jones, C.D., K.-H. Kock and S. Wilhelms. 199%. Australia: 51-68. Standing stock biomass of eight species of finfish around Elephant Island and the lower Kock, K.-H. 1992. Antarctic Fish and Fisheries. South Shetland Islands (Subarea 48.1) from the Cambridge University Press, Cambridge: 359 pp. Biological characteristics of Antarctic fish stocks

Kock, K.-H. 1998. Changes in the fish biomass Moreno, C.A., P.S. Rubilar, E. Marschoff and around Elephant Island (Subarea 48.1) from L. Benzaquen. 1996. Factors affecting the 1976 to 1996. CCAMLR Science, 5: 165-189. incidental mortality of seabirds in the Dissos- tichus eleginoides fishery in the southwest Kock, K.-H. and A. Kellermann. 1991. Reproduction Atlantic (Subarea 48.3,1995 season). CCAMLX in Antarctic notothenioid fish: a review. Ant. Science, 3: 79-91. Sci., 3 (2): 125-150.

Kock, K.-H. and I. Everson. 1997. Biology and Ni, J.-H. and E.J. Sandeman. 1984. Size at maturity ecology of mackerel icefish, Champsocephalus for northwest Atlantic redfishes (Sebastes). Can. gunnari: an Antarctic fish lacking haemoglobin. J. Fish. Aquat. Sci., 41: 1753-1762. Comp. Biochem. Physiol., 118A (4): 1067-1077. Permitin, Y.Y. and Z.S. Silyanova. 1971. New data Kock, K.-H. and C. Stransky. 2000. The composition on the reproductive biology and fecundity of of the coastal fish fauna around Elephant Island fishes of the genus Notothenia (Richardson) in (South Shetland Islands). Polar Biol., (in press). the Scotia Sea (). Vopr. Ikthiol., 11 (5): 806-819 (in Russian). Transl. as J. Ichthyol., 11 Kock, K.-H., G. Duhamel and J.-C. Hureau. 1985. (5): 693-705. Biology and status of exploited Antarctic fish stocks: a review. BIOMASS Sci. Ser., 6: 1-143. Permitin, Y.Y. and M.I. Tarverdiyeva. 1972. The Kock, K.-H., S. Wilhelms, I. Everson and J. Groger. food of some Antarctic fish in the South 1994. Variations in the diet composition and Georgia area. Vopr. Ikthiol., 12 (1): 120-132 (in feeding intensity of mackerel icefish (Champso- Russian). Translated as J. Ichthyol., 12 (1): cephalus gunnari) at South Georgia (Antarctic). 104-114. Mar. Ecol. Prog. Ser., 108 (1-2): 43-57. Riehl, R. and W. Ekau. 1990. Identification of Kompowski, A. and C. Rojas. 1993. On some Antarctic fish eggs by surface structure as shown diagnostic features of Muraenolepis sp. (eel-cod) by the eggs of Trematomus eulepidotus (Teleostei, from the South Georgia shelf. Acta Ichthyol. Nototheniidae). Polar Biol., 11: 27-31. Piscat., 23 (1): 89-98. Sherbich, L.V. 1976. Length-age composition and Kozlov, A.N., K.V. Shust and A.V. Zemsky. 1990. growth in Notothenia rossii marmorata. Trudy Seasonal and interannual variation in the distribution of Electrona carlsbergi in the southern AtlantNIRO, 65: 151-159 (in Russian). polar front area (the area to the north of South Georgia is used as an example). In: Selected Shust, K.V. and I.A. Pinskaya. 1978. Age and rate Scientific Papers, 1990 (SC-CAMLX-SSP/7). of growth of six species of nototheniid fishes CCAMLR, Hobart, Australia: 337-367. (family Nototheniidae). Vopr. Ikthiol., 18 (5): 837-843 (in Russian). Translated as J. Ichthyol., Lmkowslu, T. and C. Zukowski. 1980. Observations 18 (5): 743-749. on the growth of Notothenia neglecta Nybelin and Notothenia rossii marmorata Fischer in Silyanova, Z.S. 1981. Oogenesis and stages of Admiralty Bay (King George Island, South maturity of fishes of the family Nototheniidae. Shetland Islands). Pol. Polar Res., 1(2-3): 155-162. J. Ichthyol., 21 (4): 81-89.

Linkowski, T., P. Presler and C. Zukowski. 1983. Sosinski, J. 1985. Some data on and Food habits of nototheniid fishes (Nototheniidae) biology of Antarctic icefish Champsocepkalus in Admiralty Bay (King George Island, South Shetland Islands). Pol. Polar Res., 4 (14): 79-95. gunnari Lonnberg 1905. Acta Ichthyol. Piscat., 15: 3-54. Mazhirina, G.P. 1990. On reproduction of Electrona carlsbergi (Thing). In: Selected Scientific Papers, Tiedtke, J.E. and K.-H. Kock. 1989. Structure and 1990 (SC-CAMLR-SSPI7). CCAMLR, Hobart, composition of the demersal fish fauna around Australia: 397409. Elephant Island. Arch. FischWiss., 39 (1): 143-169. Kock et al.

Table 1: Number of species and their proportion in the catch in the Southern Scotia Arc in 1998 and 1999. (NB: data from the South Shetland Islands and Ele hant Island were available in 100 m steps, while those for the South Orkney Islands were only avaiible at 50-150.151-250 and 251-500 m intervals).

Species Elephant Island Lower South Shetlands South Orkney Islands n = 37 n = 35 n = 64 Total Weight % Total Total % Total Total % Total (kg) Weight (kg) Weight (kg) Demersal species Artedidraconidae Arfedidraco skoftsbergi 0.01 0.00 Dolloidraco longedorsalis 0.02 0.00 Pogonophryne spp! 0.95 0.03 15.54 0.10 Bathydraconidae Bathydraco ~narri 0.05 0.00 Gerlachea ausfralis 0.04 0.00 Gymizodraco acuficeps

Psetidochaenichfhys georgiant~s Nototheniidae Dissosfichtis masosoni Gobiorzototlzen gibberifrons Lepidonotofhen larseni Lepidonofotlzen nudifrons Lepidonotothen squairzifvons Nofothenia coriiceps Nofofhenia rossii Pagofhenia borchgvevinki Pleuragramnza antarcficuin Tremafonzt~sbernacclzii Tvematomus eulepidotz~s Tremafoinus hansoni Tren~atonzusnezunesi Trelnatomus nicolai Trematomus pennellii Trematonzus tokarevi

Microstomatidae Nansenia anfarcfica Biological characteristics of Antarctic fish stocks

Table l (continued)

Species Elephant Island Lower South Shetlands South Orkney Islands n = 37 n = 35 n = 64 Total Weight % Total Total % Total Total % Total (kg) Weight (kg) Weight (kg) Gynlnoscopelus braueri 0.04 0.00 0.07 0.00 1.04 0.00 Gyirrnoscopelus nickolsi 15.40 0.21 108.26 3.46 28.49 0.18 Gymnoscopelus opisthopterus 0.33 0.00 0.04 0.00 Gyinnoscopelus s p 0.14 0.00 Krqfliicktkys aii&r;soni 0.01 0.00 0.01 0.00 Protomyctophuin bolini 0.02 0.00 Notosudidae Scopelosat~rus kainiltoni 0.05 0.00 Paralepididae Magnisudis prionosa 0.46 0.00 Notolepis coatsi 0.01 0.00 Scopelarchidae Benthalbella elongata 0.08 0.00 Total 7 420.15 100 3 130.94 100 16 167.53 100

A study of members of the genus Pogonophvyne is currently under way. The taxonomy of the genus Muraenolepis is unclear (Chiu and Markle, 1990; Kompowski and Rojas, 1993). Kock et al.

Table 2: Parameters of the allometric relationship of length and weight for channichth ids, nototheniids and myctophids in the southern Scotia Arc region. E - Elephand Island, SO - SoutK Orkney Islands, SS - South Shetland Islands.

Nototheniidae Gobionotothen Biological characteristics of Antarctic fish stocks

Table 3: Estimates of length (cm) at which 50% of the population has developed beyond the immature stage (L50) and the mature stage (L,,SO),for fish collected around Elephant Island and the lower South Shetland Islands in 1998 and around the South Orkney Islands in 1999.

Species Sex South Orkney Islands Elephant Island South Shetland Islands

n h0 L1?~50 T2 L5~ LnS~ 72 L50 L~f!50 Chaelzocephalus aceratus F 1290 49.0 57.6 172 49.5 57.2 193 47.7 58.3 M 895 36.1 44.0 108 39.5 44.6 202 38.2 46.9 Chaenocephalus acevatus F 473 48.4 - 3 300 45.6 57.1 (Kock, 1986, 1989a) M 425 40.5 - 1 358 41.1 45.7 - Champsocephalus gunnnri F 360 29.5 35.3 910 31.4 44.8 777 31.3 37.7 M 452 33.8 39.1 728 32.0 46.2 770 32.1 35.6 Chionodracorastrospinost~s F 1458 34.0 36.7 177 34.9 39.6 182 34.4 38.9 M 1836 32.9 35.6 66 36.5 37.6 206 34.4 36.4 Chioizodraco rastrospinnsus F 466 31.3 36.7 - (Kock, 1989a) M 487 32.7 33.3 - Pseudochaenichthys F 935 38.4 45.6 - geovgianus M 974 38.1 45.1 - Gobior~otothengibberifrons F 7 730 32.0 34.6 2 943 36.0 39.5 717 33.4 39.0 M 7 152 30.0 33.0 4 404 30.1 36.4 740 30.7 33.7 Gobiotzotothen gibberifrons F - 12 646 36.4 38.6 - (Kock, 1989a) M - 13 564 35.4 35.9 - Lepidoizotothen larseizi F 511 14.4 16.9 - M 219 17.3 22.5 - Lepidonotothen squaiizifrons F 3 172 32.6 36.8 - 251 30.5 32.4 M 2 588 34.8 209 29.4 - Notothelzia rossii F 66 47.6 51.9 - M 86 - 42.5 - Notothenin rossii F 140 49.9 52.6 - (Kock, 1989a) M 872 42.2 45.2 - Trenzatoinz~seulepidotus F 111 27.5 27.8 - M 101 22.4 22.4 - Kock et al.

Table 4: Mean gonadosomatic index, minimum, maximum and variance of females and males of several channichthyids, nototheniids and Muraenolepis microps in the southern Scotia Arc region in March 1998 and March 1999. E - Elephand Island, SO - South Orkney Islands, SS - South Shetland Islands.

Species Area Sex n Mean Min. Max. Variance Channichthyidae Chaenocephalus aceratus SS F 2 15.02 10.26 14.87 SO F 71 14.3 2.06 25.35 20.93 M 17 1.93 0.84 2.70 0.23 Champsocephalus gunnari SS F 6 15.02 9.74 22.27 4.79 SO F 224 6.52 0.93 11.29 3.91 M 212 2.29 0.28 6.45 0.45 Chionodraco rastrospinosus SS F 10 24.66 20.96 28.64 3.29 SO F 70 20.22 11.76 25.94 9.59 M 8 3.96 1.67 16.00 24.00 Nototheniidae Gobionotothen gibberifvons SO F 2 7.48 5.97 8.99 4.56 Lepidonatothen larseni SO F 4 7.26 5.13 11.54 8.48 Lepidonotothen nudfrons SS F 2 17.19 15.38 20.00 SO F 6 17.15 10.87 23.81 35.62 Lepidonotothen squamifrons SO F 1 8.20 Notothenia coriiceps SS F 2 10.11 9.22 11.02 SO F 7 9.38 6.95 13.05 2.20 M 14 9.22 2.58 14.26 3.15 Notothenia rossii SO F 9 12.50 4.22 19.38 26.65 M 17 9.06 2.21 22.55 37.62 Pseudochaenichthys georgianus SO F 3 8 8.12 4.07 18.56 7.09 M 23 1.26 0.53 2.00 0.09 Trematomus bernacchii SO F 2 3.90 3.21 4.59 0.95 Trematomus eulepidotus SO F 36 18.84 10.00 27.78 17.40 M 29 6.14 3.70 10.56 2.41 Trematomus hansoni SO F 6 9.65 2.20 24.88 108.66 Trematomt~snezunesi SO F 6 11.25 9.09 14.00 5.41 Muraenolepidae Muraenolepis microps SS F 1 8.55 SO F 1 10.13 Biological characteristics of Antarctic fish stocks

Table 5: Egg diameter (fresh), gonadosomatic index and estimated time of spawnin in 14 species of Antarctic nototheniids and channichihyids fomd at the South Orkney Islands. S0 - &uth Orkney Islands, SS - South Shetland Islands.

Nototheniidae Gobionotothen

Nototlzenia rossii

* Measured from a few residual eggs. Kock et a1

Figure la: Location of fishing stations around Elephant Island in March 1998.

Figure 1b: Location of fishing stations around the South Shetland Islands in March 1998. Biological characteristics of Antarctic fish stocks

Longitude

Figure lc: Location of fishing stations around the South Orkney Islands in March 1999.

Elephant Island

A South Shetland Islands

South Orkney Islands

Dimension 1

Figure 2: MDS plot of species similarities in the three study areas. Kock et al.

14 7 G. gibberifrons n G. gibberifrons S. Orkney Is, I S. Shetland Is, n = 2 288

18 7 L. squamifrons [ L. squamifrons 1 16 fa Elephant 1, n = 488 14 1 n l I S. Shetland Is, n=493 1

7 C. aceratus 1 S. reS

Length (cm) Length (cm)

Figure3a: Length-frequency histograms for Gobionotothen gibberifrons, Lepidonotothen sqtiamifvons and Chaenocephalus aceratus collected at Elephant Island, the lower South Shetland Islands and the South Orkney Islands. Biological characteristics of Antarctic fish stocks

l4 I C. rasfrospinosus ,, Elephant 1, n = 243 n n 'L I D S. Shetland Is, n = 388 I II II I

20

South Shetland Is 15 combined, n = 48 8 W X l0

u3 S! LL 5

0 23 27 31 35 39 43 47 23 27 31 35 39 43 47 51 55 59 63

Length (cm) Length (cm)

Figure 3b: Length-frequency histograms for Chionodraco rastrospinosus, Charnpsocephalus gunnari and Notothenia rossii collected at Elephant Island, the lower South Shetland Islands and the South Orkney Islands. Kock et a1

30 25 L. larseni I L. larseni 1

Elephant 1, n = 493

25 14 D. mawsoni 1 N. coriiceps Elephant I and Elephant I, n = 86 20 S. Shetland Is U S. Shetland Is, n=705 combined, n = 32

15

10

5

0 14 22 30 38 46 54 62 70 78 86 94

Length (cm) Length (cm)

Figure 3c: Length-frequency histograms for Lepidonotothen larseni and Gyn~noscopelus nicholsi collected at Elephant Island, the lower South Shetland Islands and the South Orkney Islands, and Dissostichus mazusoni and Notothenia coriiceps collected at Elephant Island and the lower South Shetland Islands. Biological characteristics of Antarctic fish stocks

E. antarctica S. Orkney Is, n = 995

20 S. Orkney Is, n = 371

15

S X 10 a, U a, LL 5

0 20 22 24 26 28 30 32 34 36 38 40 42 44 46 15 17 19 21 23 25

Length (cm) Length (cm)

Figure 3d: Length-frequency histograms for selected species collected at the South Orkney Islands. Kock et al.

1600 1600 - G. gibberifrons G. gibberifrons (n= 368) 1400 I4O0 S. Shetland Is (n= 160) W=0.0021 L3 4353 S. Orkney Is W=0.0008L37025

1200 A Elephant I (n= 203) W=0.0022L34389

1000 U) 800 .- S 600

400

200

1800 1800 L. squamifrons L. squamifrons (n= 339) 1600 1600 S. Shetland Is (n= 11 6) W=0.0023L3 4444 S. Orkney Is W=0.0033L33Q6 1400 I Elephant I (n= 94) W=0.0023L34586 I I 1400

Length (cm) Length (cm)

Figure 4a: Length-weight relationships for Gobionotothen gibberifrons, Lepidonotothen squamifrons and Chaenocephalus aceratus collected at the South Shetland Islands, Elephant Island and the South Orkney Islands. Biological characteristics of Antarctic fish stocks

C. gunnari C. gunnari (n= 530) S. Shetland Is (n= 166) W=0.006L3 S. Orkney Is W=0.0017L34a1 A Elephant I (n= 309) W=0.0008L3.581

1400 1400 C. rastrospinosus C. rastrospinosus (n= 321) $200 - S. Shetland Is (n=346) W=0.0004L3.8557 A 1200 S. Orkney Is W=0.00077L3.68221 Elephanl

3500 3500 - N. coriiceps N. coriiceps (n= 32)

S. Shetland Is (n= 156) W=0.0075L3 2374 S. Orkney Is W= 0.01 9327L2 y8645 3000 A 3000 A Elephant I (n= 107) W=0.0358L281y6

2500 2500 -m 2000 .-g, 3 /. . . 15001000 15001000

500 500 30 35 40 45 50 55 30 35 40 45 50 55

Length (cm) Length (cm)

Figure 4b: Length-weight relationships for Champsocephalus gtinnari, Chionodraco rastrospinosus and Nototlzenia coriiceps collected at the South Shetland Islands, Elephant Island and the South Orkney Islands. Kock et a1

P. georgianus (n= 64) P. georgianus (n= 21 2) S. Shetland Is W= 0.0012L35685 S. Orkney is W= 0.00052L37y"4

120 N. rossii (n= 147) L. larseni (n= 222)

S. Orkney Is W= 0.00819L3 1603' 5000 I 100 S. Orkney Is W= 0.004171 L3240563

70 C. antarcticus (n= 181 ) S. Orkney Is S. Orkney Is W= 0.00061 8L35z3y 60

E. antarctica (n= 199) W= 0.20425L1 y6179

Length (cm) Length (cm)

Figure 4c: Length-weight relationships for Pseudochaenichthys georgianus collected at the South Shetland Islands and the South Orkney Islands, and Notothenia rossii, Lepidonotothen larseni, , Electrons antarctin and Gymnoscopelus nicholsi collected at the South Orkney Islands. Biological characteristics of Antarctic fish stocks

700 - 1800 . T. eulepidofus (n = 146) T. hansoni (n = 51) I6O0 600 S. Orkney Is W= 0.002087L3.582865 S. Orkney Is W= 0.001380L363149 1400 500 1200

400 1000

300 800 600 200 400 100 200

0 0 10 15 20 25 30 35 40 10 15 20 25 30 35 40 45

Length (cm) 225 T. newnesi (n = 24) *0° S. Orkney Is W= 0.0001 18L4.048450 .

Length (cm)

Figure 4d: Length-weight relationships for Trematomus eulepidotus, Trematomus hansoni and Trematomus newnesi collected at the South Orkney Islands. Kock et al.

Length (cm) Length (cm)

Figure 5a: Proportion of fish at length at which gonads are developing and maturing: Gobionotothen gibberifvons from Elephant Island, the lower South Shetland Islands and the South Orkney Islands. Dashed lines position L5" and Llrd0estimates. Biological characteristics of Antarctic fish stocks

25 30 35 40 45 50 35 40

Length (cm) Length (cm)

Figure 5b: Proportion of fish at length at which gonads are developing and maturing: Chionodraco rastrospinosus from Elephant Island, the lower South Shetland Islands and the South Orkney Islands. Dashed lines position L50 and Lm50 estimates. Kock et a1

C. aceratus - male

C. aceratus- male

Length (cm) Length (cm)

Figure 5c: Proportion of fish at length at which gonads are developing and maturing: Chaenocephalus aceratus from Elephant Island, the lower South Shetland Islands and the South Orkney Islands. Dashed lines position L50 and L,,r50estimates. Biological characteristics of Antarctic fish stocks

O C. gnnari-em 7- C gunnari- male 0.9 Elephant l g. / Elephant I

0.8 g Stages 2-5 0 Stages 3-5 0.7

a, 0.7 d... 0.6

.-5 0.5 r eg 0.4 a 0.3

Length (cm) Length (cm)

Figure 5d: Proportion of fish at length at which gonads are developing and maturing: Cha~npsocephalt~sgz~nnavi from Elephant Island, the lower South Shetland Islands and the South Orkney Islands. Dashed lines position L5" and Lvn50 estimates. Kock et al.

Length (cm) Length (cm)

Figure 5e: Proportion of fish at length at which gonads are developing and maturing: Lepidonotothen squarnifvons from the lower South Shetland Islands and South Orkney Islands, and Pseudochaenichtkys georgianus from the South Orkney Islands. Dashed lines position L50 and Lm50 estimates. Biological characteristics of Antarctic fish stocks

Length (cm) Length (cm)

Figure 5f: Proportion of fish at length at which gonads are developing and maturing: Lepidonotothen larseni, Tvematonzus eulepidotus and Notothenia rossii from the South Orkney Islands. Dashed lines position LS0and L,>150estimates. Kock et al.

'O 1 December l987

Length (cm)

Figure 6: Length composition of Gobionotothen gibberifions caught in 3 m beam trawls at 20-30 m depth off the southwest coast of Elephant Island. Biological characteristics of Antarctic fish stocks

Liste des tableaux

Tableau 1: Nombre d'especes et leur proportion dans la capture effectuee dans la region de l'arc Scotia du Sud en 1998 et 1999. (N. B. : les donnees provenant des iles Shetland du Sud et de l'ile Elephant etaient disponibles par intervalles de 100 m, alors que celles des iles Orcades du Sud ne l'etaient qu'a 50-150, 151-250 et 251-500 m d'intervalle).

Tableau 2: Parametres du rapport allometrique entre la longueur et le poids chez les Channichthyides, les Nototheniides et les Myctophides dans la region de l'arc Scotia du Sud. E - ile ~le~hant,SO - iles Orcades du Sud, SS - iles Shetland du Sud.

Tableau 3: Estimation de la longueur (cm) a laquelle 50% de la population s'est developpee au dela du stade immature (L50)et du stade mature (Ln,50), chez des poissons collectPs autour de l'ile Elephant et au sud des iles Shetland du Sud en 1998 et autour des iles Orcades du Sud en 1999.

Tableau 4: Indice gonadosomatique moyen, minimum, maximum et variance des femelles et des mdles de divers Channichthyides, Nototheniides et de Muraenolepis microps dans la region de l'arc Scotia du Sud en mars 1998 et en mars 1999. E - ile Elephant, SO - iles Orcades du Sud, SS - iles Shetland du Sud.

Tableau 5: Diametre des ceufs (a la ponte), indice gonadosomatique et epoque estimee de la reproduction chez 14 especes de Nototheniides et de Channichthyides antarctiques trouvees aux iles Orcades du Sud. SO - iles Orcades du Sud, SS - iles Shetland du Sud.

Liste des figures

Figure la: Emplacement des stations de peche autour de l'ile Elephant en mars 1998.

Figure lb: Emplacement des stations de p@cheautour des iles Shetland du Sud en mars 1998.

Figure lc: Emplacement des stations de p@cheautour des iles Orcades du Sud en mars 1999.

Figure 2: Representation graphique de la moyenne discriminante des similarites des especes dans les trois zones d'etude.

Figure 3a: Histogramme des frequences des longueurs de Gobionotothen gibberifrons, Lepidonotothen squamifrons et Chaenocephalus aceratus collectees a Hle aephant, au sud des iles Shetland du Sud et aux iles Orcades du Sud.

Figure 3b: Histogramme des frequences des longueurs de Chionodraco rastrospinosus, Champsocephalus gunnari et Notothenia rossii collectees a l'ile Elephant, au sud des iles Shetland du Sud et aux iles Orcades du Sud.

Figure 3c: Histogramme des frequences des longueurs de Lepidonotothen Iarseni et Gymnoscopelus nicholsi collectPes 5 l'ile Elephant, au sud des iles Shetland du Sud et aux iles Orcades du Sud, et de Dissostichus mawsoni et Notothenia coriiceps collectees a l'ile ~lephantet au sud des iles Shetland du Sud.

Figure 3d: Histogramme des frequences des longueurs d'especes choisies, collectees aux iles Orcades du Sud.

Figure 4a: Rapports longueur-poids de Gobionotothen gibberifrons, Lepidonotothen squamifvons et Chaenocephalus aceratus collectes aux iles Shetland du Sud, 5 I'ile Elephant et aux iles Orcades du Sud.

Figure 4b: Rapports longueur-poids de Champsocephalus gunnari, Chionodraco rastrospinosus et Notothenia coriiceps collectes aux iles Shetland du Sud, B l'ile Elephant et aux iles Orcades du Sud.

Figure 4c: Rapports longueur-poids de Pseudochaenichthys georgianus collect6s aux iles Shetland du Sud et aux iles Orcades du Sud, et de Notothenia rossii, Lepidonotothen larseni, Cryodraco antarcticus, Electrona antarctica et Gymnoscopelus nicholsi collectes aux iles Orcades du Sud.

Figure4d: Rapports longueur-poids de Trematomus eulepidotus, Trematomus hansoni et Trematomus newnesi collectes aux iles Orcades du Sud. Kock et al.

Figure 5a: Proportion de poissons de longueur telle que les gonades sont en plein developpement et maturation : Gobionotothen gibberlfvons de l'ile ~lbphant,du sud des iles Shetland du Sud et des iles Orcades du S~td. Les pointilles illustrent les estimations de et L,,,5o.

Figure 5b: Proportion de poissons de longueur telle que les gonades sont en plein developpement et maturation : Clzionodraco rastrospinosus de l'ile Elephant, du sud des iles Shetland du Sud et des iles Orcades du Sud. Les pointillbs illustrent les estimations de LS0et L,,,5o.

Figure 5c: Proportion de poissons de longueur telle que les gonades sont en plein developpement et maturation : Chaenocephaltls aceratus de l'ile Elephant, du sud des iles Shetland du Sud et des iles Orcades du Sud. Les pointilles illustrent les estimations de LS0et L,,,,,.

Figure 5d: Proportion de poissons de longueur telle que les gonades sont en plein dbveloppement et maturation : Chainpsocephalus gunnari de l'ile ~lephant,du sud des iles Shetland du Sud et des iles Orcades du Sud. Les pointilles illustrent les estimations de et Lj),qO.

Figure 5e: Proportion de poissons de longueur telle que les gonades sont en plein developpement et maturation : Lepidonatothen squarnifions du sud des iles Shetland du Sud et des iles Orcades du Sud, et Psez~dochaenichthysgeorgianus des iles Orcades du Sud. Les pointillPs illustrent les estimations de L,, et L,,,:,).

Figure 5f: Proportion de poissons de longueur telle que les gonades sont en plein developpement et maturation : Lepidonotothen larseni, Treinatoinus eulepidotus et Notothenia rossii des iles Orcades du Sud. Les pointilles illustrent les estimations de L50 et LlriS~.

Figure 6: Composition en longueurs de Gobionotothen gibbevifvons capture dans des chaluts a perche de 3 m, B 20-30 m de profondeur au large de la cbte sud-ouest de l'ile hephant.

TaGn. 1: Y~cnoBHAOB ct HX AOnR B YnOBaX, IIOJIyVeHHblX B IOXCH0fi YaCTH AYrM CKOTHXB 1998 H 1999 rr. (NB: naHHbIe H0 K)XH~IM~~T~~H~cKHM 0-BaM H 0-By ~JI~@~HTHMenaCb no ~~O-M~T~OB~IM HHTepBanaM, a AaHHbIe no K)XH~IMOPKH~~~CKMM 0-BaM - II0 HHTepBanaM 50-150, 151-250 H 25 1-500 M).

TaGn. 2: napaMeTpb1 aJIJlObleTpHVeCKHXOTHO~I~HH~~ AnHHbI H BeCa AnX ~~~OK~OBH~IXpb16, HOTOTeHWeBbIX M MHKTO@OB~~XB WXHOW YaCTH AyrH CKOTMX.E - 0-B 3JIe@aHT, SO - WXCHble OptiHefiCKHe 0-Ba, SS - K)m~breLLIe~na~nc~cle 0-~a.

Tao'n. 3: O~~HKHnn~~br (CM), np~ ~o~opofi 50% nonynx~u~sbrruno s3 ~enono~o3penofiCT~AMM (L5"), M B CTaAHH nOJIOBO3peJIOCTH (L,,,SO),QnX pb16, ~O~~M~HH~IXy 0-Ba ~JI~@~HT H HMXH~~~ YaCTH K)XH~IX ~~T~~HACKHX0-BOB B 1998 r. H B0Kpyr K)XH~IXO~KH~~~CKHX 0-BOB B 1999 r.

TaGn. 4: CpenHHfi ~OH~~OCOM~TH~~CKM~~HHAetiC, MHHMMYM, MaKCHMyM H AHCIIePCHR AJIR CaMlJOB H CaMOK HeCKOnbKHX ~'~~OK~OBH~IXpb16, HOTOTeHHeBbIX H Muraenolepis n~icl"0psB IOXCH0fi WlCTM AyrH CKOTMRB MapTe 1998 r. Pi MapTe 1999 r. E - 0-B 3JIe@aHT, SO - mlKMb1e Op~Hefic~He0-Ba, SS - K)m~b~e~~TJX~H~CKH~ 0-Ba.

TaGn. 5: &laMeTp HKPbl (CBemefi), ~OH~~~OCOM~THY~CKH~~HHAeKC H OqeHKa BpeMeHM HepeCTa 14 BHAOB aHTaPKTHqeCKHX HOTOTeHBeBbIX H G~~OK~OBH~IXpb16, O~H~PYX~HH~IXY WXH~IX OPKH~~~CKCIX 0-BOB. SO - WXH~I~OpKHefiCKMe 0-Ba, SS - K)XHble meTna~nC~Hf20-Ba.

Pctc. la: Mec~asene~~~l npo~b~cna, 0-B 3ne@a~~, ~ap~ 1998 r.

Pac. Ib: Mec~ase~e~1.r~ npo~brcna, K)m~bre LUe~na~nc~~e 0-sa, ~ap~ 1998 r.

Pm. Ic: Mec~aBeAeHMR IlpOMbICJIa, K)XCHble Op~HefiCKlle0-Ba, MapT 1999 I?. Biological characteristics of Antarctic fish stocks

Pac. 2:

PHC.3a: rac~orpa~~b~YacToT AnaH Gobionototherz gibberifrons, Lepidonotothen squamifrons H Chaenocephalus aceratus 113 pagoao~0-sa 3ne@a~~,HHXH~~ YacTn WXH~IXme~na~~c~rnx o-BOB H ?dk~bIx OPKH~~CKBX0-BOB.

~HCTO~~~MM~IYacTOT AnHH Chionodraco rastrospinosus, Clzampsocephalus gunnari H Notothenia rossii a3 pafioao~o-sa 3ne@a~~,HLIXH~~~ YacTa K)XH~IX~U~T~~HACK~IX o-BOBH WXH~IX O~KH~~~CKHX0-BOB.

~UCTO~P~MM~IYacToT nnaa Lepidonotothen larseni H Gymaoscopelzis nicholsi a3 pafiowos o-sa 3ne@aHT, HHXH~~~YaCTH K)XH~IX~~TJI~HACK~X 0-BOB H K)XH~IX O~KH~~~CKETX 0-BOB, a TaKXe Dissostichus mawsoni H Notothenia coriiceps 113 paiio~oso-sa 3ne@aa~H ~ax~efi yaCTH K)XH~IX ~~T~~HACKHX0-BOB.

O~~orue~~e~nma-sec Aria Gobionotothen gibberifrons, Lepidonotothen squamifrons a Chaenocephalus aceratus, nofi~a~~brxy WXH~IX UIe~na~nc~~lx o-BOB,o-sa 3ne@a~~H K)XH~IX OPKH~~~CKHX0-BOB.

O~~ome~kienna~a-sec Ana Champsocephalus gunnari, Chionodraco rastrospinosus H Notothenia coriiceps, IIO~~M~HH~IXy K)XH~IX ~~T~~HQCKHX 0-BOB, 0-Ba ~JI~@~HTH K)XH~IX O~KH~~~CKMX 0-BOB.

O~HomeHlle~n~~a-Bec nnn Pseudochaenichthys georgianus, nofi~a~~b1xy K)XH~IX me~na~~c~ax n ~OXH~IXOPKH~~~CKAX 0-BOB,a TaKme Notothenia rossii, Lepidonotothen larseni, Cryodraco antarcticus, Electrona antarctica a Gymnoscopelus nicholsi, nofi~a~~brxB paiio~e K)m~blx O~KH~~~CKHX0-BOB.

O~~orue~aennaaa-~ec Aria Trematomus eulepidotus, Trematomus hansoai H Trematomus newnesi, ~O~M~HH~IXB pafi0He K)XH~IXO~KH~~~CKHX 0-BOB.

Aona p616 c Ana~oii,npH ~o~opofiP~~BHB~~TCII H cospesam~ roHanb1: Gobionotothen gibberifrons H3 ~~~OHOB0-Ba ~JI~@~HT, HHXH~~ YaCTH K)XH~IX~~T~~HACKHX 0-BOB H WXH~IXOPKH~~~CKMX 0-BOB. IIYHKTMPOMno~a3a~b1 oqeHKH H L!n50

Aona pb16 C nnn~ofi,npH ~o~opofi~~SBMB~IOTC~ H cospesam~ roHaAb1: Chionodraco rastrospinosus H3 pafi0~0B0-Ba ~A~@HT,HMXH~~~ YaCTEl K)XH~IX~~T~~HACKHX 0-BOB H K)XHMXOPKH~~~CKAX 0-BOB. ~YHKT~~POMHOKa3aHbI 04eHKM LsOH

Aona p616 C flJIHHofi, npH KOTO~O~~pa3BHBaK)TCII H C03peBaH)T rOHaAb1: Chaenocephalus aceratus M3 ~~~OHOB0-Ba 3ne@aHT, HMXH~~~YaCTH K)XHMX~~T~~H~cKHx 0-BOB I4 K)XH~IX O~KH~~~CKHX 0-BOB. ~YHKTMPOMIIOKa3aHbl OUeHKH H LaisO.

Aona p616 C gn~~ofi,npH KOTOPO~~P~~BHB~~TCR H co3peBamT roHaAbI: Champsocephalus gunnari a3 pafi0~0B0-Ba 3JIe@aHT, HEIXH~~~4aCTII K)XiHblX ~~TJI~HACKHX0-BOB H K)XH~IXO~KH~~~~CKHX 0-BOB. ~YHKTHPOMIIOKa3aHbI OUeHKH L50 H Lni5@

AO~Rpb16 C ,qnn~oii,npH KOTO~O~~~~~BHB~~TCR H c03pe~am~ roHaAbI: Lepidonototherz squamifrons H3 ~~BOHOBHLIXH~~~ YaCTII K)XH~IXmeTnaHflCKUX 0-BOB H K)-n

Aonn pb16 C nna~oii,npH KOTO~OG~~~BHB~IOTCII a co3pesa10~ roaagbl: Lepidonotothen larseni, Trematomus eulepidotus H Notothenia rossii paiio~aK)XH~IX OPKH~WCKHX 0-BOB. ~YHKTHPOM nOKa3aHbI OqeHKH L50 H LniSO.

Pac. 6: Pa3~epfibliiCOCTaB Gobionotothen gibberifrons, n0fi~aHHblx~-M~TPOB~IMII 6HM-TpaJIaMa y mro- sana~~oro6epera o-sa 3ne@a~~~a rny6~ae 20-30 M. Kock et al.

Lista de las tablas

Tabla 1: Numero de especies y su proporcion en la captura realizada en el sur del arco de Escocia en 1998 y 1999. (NB: 10s datos de las islas Shetland del Sur y Elefante provienen de estratos de 100 m de profundidad, mientras que 10s de las islas Orcadas del Sur provinieron de 10s siguientes estratos: 50-150,151-250 y 251-500 m).

Tabla 2: Parametros de la relacion alometrica talla/peso obtenidos para caenictidos, nototenidos y mictofidos en la region del sur del arco de Escocia. E - isla Elefante, SO - islas Orcadas del Sur, SS - islas Shetland del Sur.

Tabla 3: Estimaciones de la talla (cm) alcanzada cuando 50% de la poblacion se ha desarrollado mis alla del estadio de inmadurez (Ls0)y de madurez para 10s peces capturados en el Brea de isla Elefante y las islas australes de Shetland del Sur en 1998 y alrededor de Orcadas del Sur en 1999.

Tabla 4: Minimo, maximo, promedio y variancia del indice gonadosom&ticode hembras y machos de varios caenictidos, nototenidos y Mz~raenolepisrnicrops en la region sur del arco de Escocia en marzo de 1998 y marzo de 1999. E - Isla Elefante, SO - islas Orcadas del Sur, SS - islas Shetland del Sur.

Tabla 5: Diimetro del huevo (fresco), indice gonadosomatico y estimacion de la epoca de desove para 14 especies de nototenidos y caenictidos capturados en Orcadas del Sur. SO - islas Orcadas del Sur, SS - islas Shetland del Sur.

Lista de las figuras

Figura la: Estaciones de pesca realizadas en el area de isla Elefante en marzo de 1998.

Figura lb: Estaciones de pesca realizadas en el area de Shetland del Sur en marzo de 1998.

Figura lc: Estaciones de pesca realizadas en el Brea de Orcadas del Sur en marzo de 1999.

Figura 2: Grsfico de 10s resultados discriminantes minimos de las similitudes de las especies en las tres areas de estudio.

Figura 3a: Histogramas de la frecuencia de tallas de Gobionotothen gibberifrons, Lepidonotothen sqzlamifrons y Clzaenocephalus aceratus capturados en isla Elefante, las islas australes de Shetland del Sur y en las islas Orcadas del Sur.

Figura 3b: Histogramas de la frecuencia de tallas de Chionodraco rastrospinosus, Champsocephalus guntzari y Nototheilia rossii capturados en isla Elefante, las islas australes de Shetland del Sur y en las islas Orcadas del Sur.

Figura 3c: Histogramas de la frecuencia de tallas de Lepidonotothen larser~iy Gymnoscopelus nicholsi capturados en isla Elefante, las islas australes de Shetland del Sur y en las islas Orcadas del Sur, y Dissostichz~smawsoni y Notothenia coriiceps capturados en isla Elefante y en las islas australes de Shetland del Sur.

Figura 3d: Histogramas de la frecuencia de tallas de una selection de especies capturadas en las islas Orcadas del Sur.

Figura 4a: Relacion talla/peso de Gobionotothen gibberifrons, Lepidonotothen squalnzfrons y Ckaenocephalus aceratus capturados en las islas Shetland del Sur, Elefante y Orcadas del Sur.

Figura 4b: Relacion talla/peso de Champsocephalus gunnari, Chionodraco rastrospinosus y Notothenia coriiceps capturados en las islas Shetland del Sur, Elefante y Orcadas del Sur.

Figura 4c: Relacion talla/peso de Pseudochaenichthys georgianus capturado en las islas Shetland del Sur y Orcadas del Sur, y Notothenia rossii, Lepidonotothen larseni, Cryodraco antarcticus, Electrona antarctica y Gyrnnoscopelus nicholsi capturado en las islas Orcadas del Sur. Biological characteristics of Antarctic fish stocks

Figura 4d: Relacion talla/peso de Tveinatolnus eulepidotus, Tvematomus Izansoni y Tre?natomusnewnesi capturado en las islas Orcadas del Sur.

Figura 5a: Proporcion de peces de talla correspondiente a1 desarrollo y maduracion de las gonadas: Gobionotothen gibberifruns de isla Elefante, las islas australes de Shetland del Sur y las Orcadas del Sur. Las lineas entrecortadas indican las estimaciones de LsOy L,,,so.

Figura 5b: Proporcion de peces de talla correspondiente a1 desarrollo y maduracion de las gonadas: Chionodvaco vastrospinosus de isla Elefante, las islas australes de Shetland del Sur y las Orcadas del Sur. Las lineas entrecortadas indican las estimaciones de Lsa y L,,sc

Figura 5c: Proporcion de peces de talla correspondiente a1 desarrollo y maduracion de las gonadas: Chaenocephalus acevatus de isla Elefante, las islas australes de las Shetland del Sur y las Orcadas del Sur. Las lineas entrecortadas indican las estimaciones de L50 y LniSO.

Figura 5d: Proporcion de peces de talla correspondiente a1 desarrollo y maduracion de las gonadas: Champsoceplzalus gunnavi de isla Elefante, las islas australes de Shetland del Sur y las Orcadas del Sur. Las lineas entrecortadas indican las estimaciones de L50 y L,,,sO

Figura 5e: Proporcion de peces de talla correspondiente a1 desarrollo y maduracion de las gonadas: Lepidonotothen squanzifrons de las islas australes de Shetland del Sur y las Orcadas del Sur, y Pseudochaeizichthys geovgianus de las islas Orcadas del Sur. Las lineas entrecortadas indican las estimaciones de LS0 y L,,,50.

Figura 5f: Proporcion de peces de talla correspondiente a1 desarrollo y maduracion de las gonadas: Lepidonotothen lavseni, Tvematomus eulepidotzis y Notothenia vossii de las islas Orcadas del Sur. Las lineas entrecortadas indican las estimaciones de L50 y L,,)SO.

Figura 6: Cornposicion por tallas de Gobionotothen gibbevifvons capturado en arrastreros de vara de 3 m a 20-30 m de profundidad frente a la costa suroeste de la isla Elefante.