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Home , Cookeolus japonicus, Cutlassfish, Demersal fish, Malacocephalus laevis, Stomias affinis, Thyrsitops lepidopoides

MARINE ECOLOGY PROGRESS SERIES Vol. 108: 59-77,1994 Published May 12 Mar. Ecol. Prog. Ser. l

Demersal bony of the outer shelf and upper slope of the southern Brazil Subtropical Convergence Ecosystem

Manuel Haimovicil, Agnaldo Silva n art ins^, Jose Lima de ~igueiredo~, Pedro Castelli vieira1

Departamento de Oceanografia. Fundaglo Universidade do Rio Grande, Caixa Postal 474, 96201-900 Rio Grande. RS. Brazil Curso de Pos-Graduaqao em Oceanografia Biol6gica, Fundaqao Universidade do Rio Grande, Caixa Postal 474, 96201-900 Rio Grande. RS, Brazil Museu de Zoologia da Universidade de Sio Paulo. Caixa Postal 7172. 01064-980 Sao Paulo. Brazil

ABSTRACT. Ninety-three of bony were caught in 4 seasonal bottom-trawl surveys carried out between July 1986 and May 1987 on the outer shelf and upper slope (124 to 587 m depth) along the southern Brazilian coast (30°40' to 34"30' S). On the outer shelf (< 179 m), the demersal- pelagic species Trichiurus lepturus, lathami, Cynoscion guatucupa, japonicus, and predominated and also to a lesser degree the demersal benthonic Umbrina canosai and Mullus argentinae. Antiyonia capros and Priacanthus arenatus were found associated with the relic hard bottoms of the shelf break (180 to 249 m). Further offshore, the demersal-pelagic species Ariomma bondi and Zenopsis conchifera and the demersal benthonic species Polyprion ameri- canus and Helicolenus lahillei were abundant, both associated with rocky bottoms. The macrourids Coelorinchus marinii and occidentalis characterized deep-water hauls p450 m). Frequent and widespread, but less abundant in the catch, were Polymixia lowei, Urophycis mystacea and Merluccius hubbsi. Mean total catch (kg h-') decreased 6-fold and the number of species by more than half along the depth range, with a sharp step at 350 m. Both catch and number of species were slightly higher in the winter cruises. Most species occurred in both winter and summer-autumn cruises, but, with increasing depth, the relative abundance of species that occur year-round decreased, whereas fishes that occur mostly in winter increased. The catch of demersal- decreased sharply below 350 m and differed little among seasons; catches of demersal-benthonic fish were more evenly distributed across the depth range and were larger in winter and spring. The high number of species on the shelf break may be attributable to the higher variety of soft and consolidated substrates and the overlapping of different water masses along the . The north-south shift of the western boundary of the Subtropical Convergence appears to be mainly responsible for the seasonal changes in abundance of the species.

KEY WORDS: Subtropical Convergence . . Distribution . Southern Brazil . Outer shelf - Upper slope . Fish communities . Demersal survey

INTRODUCTION The marine fish fauna of the southwestern Atlantic, particularly the demersal fishes from the shelf break During 1986 and 1987,4 bottom trawl surveys on the and the upper slope of the coast of southern Brazil, has external shelf and upper slope off southern Brazil were scarcely been studied. Early Brazilian ichthyological carried out from the RV 'Atlantic0 Sul' to assess the surveys were conducted only to 200 m depth (Vazzoler potential of the area; this proved to be rather 1975, Benvegnu-Le 1978). In surveys performed by poor (Vooren et al. 1988, Haimovici & Perez 1991a) but research vessels of other nations, e.g. RV 'Calypso' in included more than 100 species, many of them com- 1961 (Roux 1973) and RV 'Walter Herwig' in 1966 mercially important in neighboring regions. (Yesaki 1973), only a few stations were in our

O Inter-Research 1994 Resale of full article not permitted Mar. Ecol. Prog. Ser. 108: 59-77, 1994

studied area. Thus, one of the objectives of this paper MATERIALSAND METHODS was to report the teleost fishes in the catches, their sizes and relative abundance over the depth range and Samples were obtained in 4 groundfish survey the cruises and to provide some information about the cruises of the RV 'Atldntico Sul' in July 1986 (winter), life history of better-represented species in the survey. September 1986 (late winter), March 1987 (late An analysis of trends in the relative abundance and summer), and May 1987 (autumn) over the outer shelf number of species in relation to depth, temperature, and upper slope between Chui (34" 30' S) and Cape of latitude, and seasons of the year is also presented. Santa Marta Grande, Brazil (28"40f S). Each cruise Some comments on the general composition of the fish covered approximately half of the area (Fig. 1). fauna of the region are included in the 'Discussion'. Sixty-five fish samples were collected using a bottom As this deeper area is scarcely fished as compared trawl net with a 23.4 m footrope geared with 40 cm to the (Vooren et al. 1988, Hairnovici diameter steel bobbins and a 50 mm stretch-mesh et al. 1989b), its fauna1 composition is probably in an end. The standard duration of the hauls was 60 min at almost natural undisturbed state, therefore the present a speed of 3.0 knots. After each haul bottom tem- study is a good referential base for temporal compar- peratures were recorded. All hauls were performed isons or for comparisons with other regions sampled between dawn and dusk. Tow depth ranged from 124 with equivalent gear. to 587 m: 30% of the hauls were conducted between 124 and 179 m, 21 % between 180 and 249 m, 21% between 250 and 349 m, 12 % between 350 and 449 m and 14% be- tween 450 and 587 m. Irregular hard bottoms are common in canyons in the shelf break, per- pendicular to the coastline from Albardao to Rio Grande, and there are no extensive areas for trawling in the study area (see Vooren et al. 1988). Temperature and salinity were measured with Nansen bottles at standard depths and along fixed transects at the be- ginning and end of each cruise and included in the survey final report by Caste110 (1991).When possible bottom temperature was recorded at the fishing sta- tions. At depths over 200 m mea- surements were imprecise due to strong currents, and for some fishing stations, bottom temper- atures were interpolated from transect and neighboring sta- tions. Temperature profiles are

1 shown in Fig. 2. CHUi After each tow the fishes JULY 1986 were classified, measured and SEPTEMBER 1986 weighed. For very large catches, 0 MARCH 1987 a random subsample of 30 kg 0 MAY 1987 34 of the smaller fishes was clas-

350 r1 sified. The number per hour, weight per hour and size FICJ 1. Study area of the bottom trawl survey by the RV 'Atlintico Sul' off southern Brazil in 1986 and 1987. Empty and full circles and squares ind~catefishing stations Lines and position of each species were letters indicate temperature profile transects calculated. Haimovici et al.: Demersal bony fish off southern Brazil

Bony fishes were identified on board using the analysis program [DECORANA described in Gauch fish catalogs (identification guides) of Figueiredo & (1982)) for the natural logarithm of the numerical Menezes (1978, 1980), Fischer (1978), Menezes & abundance plus one [ln(x+l)]was run to investigate Figueiredo (1980, 1985) and Menni et al. (1984). the distribution patterns of the bony fishes in winter The fishes were classified as 'demersal-benthonic', and summer-autumn. Only species caught more than species that feed mostly on or near the bottom, or twice were included in the analysis. 'demersal-pelagic', that feed mainly in the water column (Angelescu & Prenski 1987). Some meso- pelagic species were also caught. The classification SURVEYAREA criterion was based on observation of the functional morphology, unpublished data on stomach contents Bottom topography and morphology. The external and literature information on the species, genera or shelf has a declivity of around O.lO,becoming about 1" family. in the upper slope. The shelf break is between 150 and For each cruise and depth range the total number 185 m and is not abrupt. Between Chui and Rio Grande and mean number of species per tow and the mean (34'20' to 32'00' S) the shelf is 140 to 180 km wide, total catch (in kg h-') of demersal-benthonic, demersal- becoming narrower to the north, with a minimum of pelagic and mesopelagic species were calculated. 90 km at the Cape of Santa Marta Grande (28'40' S). Several sources of bias are involved in abundance The morphology and of the continental shelf comparisons, as species and sizes are not equally of Rio Grande do Sul were summarized by Martins et accessible and vulnerable to bottom trawls. This is a al. (1975). The inner shelf is dominated by sandy bot- limitation of the exploratory fishing survey method that toms, but biodetrital shell banks exist parallel to the must be borne in mind. A reciprocate correspondence coast off Patos and Mirim . Sandy mud and

. :'c . . . . A: l9 . . .. . b19. . .

300-

TORRES September 1986

0 - 0

-100

200- -200

300- -300

'a - 400 SOLID~O May 1987 500

Fig. 2. Temperature profiles In the bottom trawl survey by the RV 'Atlbntico Sul' off southern Brazil in 1986 and 1987. Letters indicate the transects in Fig. 1 Mar. Ecol. Prog. Ser. 108: 59-77, 1994

muddy sand are dominant in the middle shelf, while Subtropical Water (SW), also called South Atlantic mud rich in silts, clay and biodetrital sediments are Central Water, with temperatures ranging from 10 to found in the outer shelf. Relic coral hard bottoms are 20°C and salinities from 34.3 to 35.9 ppt, is found found along the shelf break. Mud is dominant in the below the Brazil Current. It results from the mixing slope but irregular hard bottoms are common of TW and Subantarctic Water (SAW) in the Sub- in canyons perpendicular to the coast off Albardao tropical Convergence zone, which fluctuates season- (33" 20' S) and north of Rio Grande (32" 10' S). ally between 35 and 45" S (Legekis & Gordon 1982, Benthic and demersal macrofauna. The macroepi- Olson et al. 1988). This water may upwell seasonally benthonic fauna of the area was studied off northern Rio Grande do Sul, Santa Catanna and by Capitoli & Bonilha (1991) and D'Incao & Ruffino Cabo Frio or follow the meander-like pattern of the (1991). In the soft bottoms of the external shelf and Brazil Current. SAW, derived from a coastal branch upper slope of silty clay sediments the of the Malvinas/Falkland Current, extends up to Diopatra tnden tata and Onuphis tenuis were com- 32" S but may reach further north in winter. Usually mon and the small Chasmocarcinus typicus was it penetrates beneath the Coastal Water between the dominant. Skeletons and living hermatypic 50 and 100 m isobaths. Its temperature off Chui is Cladocora debilis and Rhizopsammia manuelensis 10 to 12°C and can approach 14 to 16°C off Rio and gorgonians of the Primnoella were domi- Grande; salinity ranges from 33.7 to 34.15 ppt. Along nant on biodetrital sediments found extensively in its eastern boundary a strong thermal gradient, clas- the external shelf to the north of Rio Grande and all sified by Miranda et al. (1973) as Slope Water, with along the break of the slope. From 300 to 500 m intermediate temperature and salinity, separates it patches of consolidate sedimentary rocks are com- from the Brazil Current. processes occur mon where the Eunice frauenfeldi and along the shelf break year-round but with higher hermatypic corals were found. The more frequent intensity in summer (Lima 1992). Intermediate and widespread macrocrustaceans were the demer- Antarctic Water (IAW) originating at the Antarctic sal Peneaopsis serrata, Parapenaeus ameri- Convergence may be recognized by its lower salinity canus and Parapandulus sp., the brachiurid crab Por- at depths between 700 and 1100 m (Thomsen 1962). tunus spinicarpus and several anomurans of the Along the continental slope this water may reach up genus Munida, the latter frequently preyed upon by to 400 m with salinities between 34.26 and 34.41 ppt several of the fish species sampled. In the outer shelf and temperature under 10°C in winter at the latitude and break, the stomatopod Squilla brasiliensis and of Rio Grande. the small Speocarcinus sp. and C. typicus were Bottom morphology contributes to explaining the also common, and in deeper waters the large crab behavior of the water masses: in winter, SAW of the Chaceon notialis, this last species offering some inner branch of the MalvinadFalkland Current pene- fishing potential (Lima & Lima 1991). trates onto the wide shelf from the south and reaches at Thirty species of elasmobranch fish were collected in most up to Conceiqdo (31'40' S).To the north the shelf the same survey (Vooren 1991), and 24 of them were is narrower and the influence of the Brazil Current is also found in shelf surveys. Among the most frequent more evident, particularly in the warm seasons, while were the Galeorhinus and Mustelus in the cold season STW may partially upwell on the schmitti in winter, and 2 species of Squatina and Raja shelf near the coast. cyclophora year-round. Six species were found exclu- Temperature and salinity profiles at the beginning sively at depths > 400 m. and end of each cruise showed that a mixture of SAW Thirteen species of cephalopods were found in the and STW dominated the external shelf and upper area, most of the catch being represented by Loligo slope, and below it IAW was found (Fig. 2). Bottom sanpaulensis and L. plei on the outer shelf, and Illex temperature ranged from 16.6 to 19.0°C (at 100 m) argentinus on the slope (Haimovici & Perez 1991a). during winter and 14.0 to 16.0°C (at 200 m) during Benthic and sepioids are scarce in the region summer-autumn surveys. Thermoclines were observed (Haimovici & Perez 1991b). between TW and SWin the upper 200 m layer. Below Hydrography. Several water masses can be identi- 200 m depth, the measurement of temperature was fied over the external continental shelf and upper imprecise, but temperature decreased gradually to slope off southern Brazil (Emilsson 1961, Miranda et under 10°C at 400 m and 6.2"C at 500 m. Bottom al. 1973, Castello & Moller 1977, Hubold 1980a, b, temperature in July 1986 in the southern external part Matsuura 1986). Tropical Water (TW) of the Brazil of shelf was found to be 2.5"C warmer than usual Current (temperature > 20 "C, salinity > 36.0 ppt) flows for the winter, probably due to a milder Malvinas/ over the slope and, due to eddies and meander Falkland Current influence in that year (Castello structures, occasionally reaches the continental shelf. 1991). Hain~ovic~et al.: Demersalbony fish off southernBrazil 63

RESULTS This survey yielded a number of species rarely caught or otherwise recorded for the first time in Brazilian Species composition waters: Dysomminia rugosa, Polymetme corythaeola, Stomlas affinis, Melanostornias niger, efful- The families, genera and species of teleost caught are gens, Gymnoscopeluspiabilis, Symbolophorus barnardi, listed in Table 1. A total of 93 species of 55 families and Neocopelus nlacrolepidotus, A4acruronus magellanlcus, 86 genera were identified. The families with the highest Benthocometes robustus, Malacocephalus laevis, Plala- numbers of species present were Serranidae (with cocephalus occiden talis, Ventrifossa ori, Beryx splen - 6 species) followed by (5), Myctophidae dens, Xenolepidichtys dalgleishi, Prometichtl~ys pro- (4),Sciaenidae (4). Trichiuridae (4). (3),Trigli- metheus, elongatus and sp. dae (3), Scorpaenidae (3),and (3). (see Nakamura & Parin 1993 for species identity). The frequency of occurrence, mean catch, mean Additional information on the distribution, sizes and weight, total length range, depth of catch and bottom life history of some species follows. temperature for each species are listed in Table 2. The Merluccius hubbsi. This is found from the coast relative abundance in different seasons (cruises) and of Rio de Janeiro State to the southern tip of South depth ranges for individual species were calculated as Anlenca (Angelescu & Prenski 1987, Fagundes & percentage of the total catch in weight and included in Gaelzer 1991). It was the most frequent teleost, occur- Table 2. ring in 37 hauls but representing only 1.18 % of total Mean weight ranged from 1 g for Maurolicus muel- bony fishes caught (Table 2). This species was taken in leri to 40 kg for Mola mola, both pelagic species. a wide range of depths and bottom temperatures, from Among those species present in more than 3 tows, only 120 to 490 m and from 6.8 to 17 'C. Total length ranged Polyprion americanus had a mean weight over 9 kg, from 8 to 48 cm; most specimens over 40 cm were and 3 species (Genypterus brasiliensis, Lophjus gastro- caught in the south and in winter (Fig. 3A), juveniles physus and PI-iacanthus arenatus) over 1 kg. under 30 cm being more abundant between the 60 and On the outer shelf, the den~ersal-pelagic species 180 m isobaths. Mature females were found only in lepturus, , Cynoscion winter. On the shelf, juveniles fed mostly on zoo- guatucupa, Scomber japonicus and Thyrsitops lepi- , and adults on fish (Engraulis anchoita, Tra- dopoides predominated and also to a lesser degree churus lathami and M. hubbsi) and (Illex the demersal-benthonic species Umbrina canosai and argen tin us and Loligo sanpaulensis). Commercial Mullus argentinae; all of them were more abundant in catches of M. hubbsi are not common in the area and shallower watel- Antigonia capros and Priacanthus are restricted to the winter season (Haimovici et al. arenatus were found associated with the relic coral 1989b). Recent studies show that the southern hard bottoms of the shelf break. Further offshore, the Brazilian coast is mainly a nursery ground for the same abundant species were the demersal-pelagic Ariomma population unit that spawns in winter off and bondi and Zenopsis conchifera, and the demersal- northern (Haimovici et al. 1993). ben thic Polyprion american us and Helicolen us lahillei, Zenopsis conchifera. The buckler dory is a species both associated with rocky bottoms, and Coelorinchus widely distributed in the Atlantic . It occurred in marinii and Malacocephalus occidentalis in deeper 34 hauls, and its length ranged from 5 to 56 cm. Larger water. Widespread, but less abundant in the catch, specimens were more frequent in the 250 to 349 m were Polymixia lowei, Urophycis mystacea and Mer- range (Fig. 3B). Yesaki et al. (1976) suggested that luccius hubbsi. there was some potential for the buckler dory, Large ichthyophagous demersal bony fishes such as but this did not appear evident with our gear; a mid- Epinephelus flavolim ba tus, Lophola thilus villarii, Gen- water trawl would probably work out better. Females ypterus brasiliensis, Pseudopercis sp. and Lophius over 35 cm were found maturing in autumn and ripe gastrophysus were rarely caught and did not occur in in winter. Z. conchifera preys mainly on Maurolicus water deeper than 350 m. m uelleri, Diaph us dumerilii and Eupha usia similis. On the winter cruises, Polypnon americanus, Scomber Macpherson (1983) found this species feeding mainly japonicus, Trichiurus lepturus, Trachurus lathami, on fishes off South Africa. Umbrina canosai and Helicolenus lahillei were the most Synagrops spinosus. Widely distributed in the west- abundant . The most frequently occurring ern Atlantic Ocean, this small fish occurred in 33 hauls, species on summer-autumn cruises were Cynoscion mainly in the southern portion of the survey area at guatucupa, Antigonia capros and Priacanthus arenatus depths greater than 350 m. Undersampled because of in the south and 7: lathami, Thyrsitops lepidopoides, its small size, but probably abundant in the region, it T lepturus, U. canosai and Zenopsis conchifera in was caught in a wide range of depths and tempera- the north. tures. It is commonly preyed upon by Pagrus pagrus 64 Mar. Ecol. Prog. Ser. 108: 59-77, 1994

Table 1 Teleost species caught In a bottom trawl survey off southern Brazil by the RV 'Atldntico Sul' in 1986 and 1987. Families are arranged in systematic order according to Nelson (1984)

Spec~es

Muraenidae Triglidae Gymnothorax ocellatus Agassiz. 1831 Bellator brachychir (Regan, 1914) Synaphobranchidae Prionotus nudigula Ginsburg, 1950 Dysommina rugosa G~nsburg,1951 Prionotus punctatus (Bloch, 1797) Congridae Polyprlonidae Conger orblgnyanus Valenciennes, 1847 Polypnon amencanus (Schnelder. 1801) Engraulididae Serran~dae Engraulis anchoita Hubbs & Marlnl, 1935 Dules aunga Cuvier, 1829 ~rgentinidae Eprnephelus tlavolimbatus Poey, 1865 Argentina strfata Goode & Bean. 1896 Holanthjas rnartinicensis (Guichenot, 1868) Sternoptychldae Prkea rosa (Gunther, 1880) Maurolicus rnuellen (Gmelin, 1788) Serranus atrobranchus (Cuvier. 1829) Phothichthyidae Polymetme corylhaeola (Alcock. 1898) japonicus (Cuvier, 1829) Storniidae PriacanLhus arenatus Cuvier, 1829 affinlsGiinter, 1887 Acropornatidae Melanostorniidae Synagrops bellus (Coode & Bean. 1896) Melanostomjas niger Gilchnst & \Ion Bonde, 1924 Synagrops spinosus (Schultz, 1940) Synodontldae Branch~ostegldae Saurida carjbbaea Breder, 1927 Caulolatrlus chrysops (Valenciennes, 1833) Chlorophthalmidae LopholaC~/us vrllarii Ribeiro. 1915 Chlorophthalmus agasslzl Bonaparte, 1840 Pornatorntdae Parasudis truculenta (Goode & Bean, 1896) Pomatomus saltatriu (Linnaeus, 1766) Neoscopelidae Carangidae Neoscopelus macrolepidotus Johnson. 1863 Decapterus tab1 Berry, 1968 Myctophidae Naucrates ductor (Linnaeus, 1758) Diaphus dumerilri (Bleeker, 1856) Trachurus lathami Nichols, 1920 Diaphus effulgens (Goode & Bean. 1896) Bramidae Gymnoscopeltrs piabibs (Whitley. 193 1) Brama brama Bonnalerre, 1788 Symbolophorus bamard~(Tanlng, 1932) Lutjanldae Bregmacerotldae Pr~stlpornordes freeman; Anderson, 1966 Bregmaceros atlanticus Goode & Bean, 1886 Sparidae Gadldae Pagrus pagrus (Linnaeus, 1758) Urophycis brasrllensis (Kdup, 1858) Sclaenldae Urophycis mystacea Ribeiro. 1903 Cynosaon guatucupa (Cuvier, 1830) Merluccidae Cynosclon jamaicensis (Vaillant & Bocourt, 1883) Merluccius hubbsr Marin1.1933 Mlcropogonias furnreri (Desmasrest, 1823) Macruronus magellanicus Lonnberg. 1907 Umbrina canosai Berg. 1895 Macrouridae Mullidae Coelorinchus rnarinii Hubbs, 1934 Mullus argentinae Hubbs & Marini. 1935 Malacocephalus laevis (Lowe. 1843) Cheilodactllydae Malacocephalus occrdental~sGoode & Bean, 1885 Sclaenoides bergi Norman, 1937 Ventrifossa on (Smith, 1968) Percophldae Ophldlidae Bembrops heterurus (Ribelro, 1903) Benthocornetes robustus (Goode & Bean, 1886) Percophis braslliensis Quoy & Gaimard. 1824 Genypterus brasiliensrs (Regan. 1903) Pingu~pedidae Pseudopercls spp. Porichthys porosissimus (Valenciennes. 1837) Callionymidae Lophiidae Slmchiropus agassizlr (Goode & Bean, 1888) Lophius gastrophysus Ribeiro, 1915 Trachichthyidae Prometlchthys prometheus (Cuvier. 1832) Hoplostethus occrdentabs Woods. 1973 Thyrsitops lepidopoides [Cuvier. 1831) Berycidae Trichiuridae Beryx splendens Lowe, 1834 Benthodesmus elongatus (Clarke, 1879) Polymixl~dae taeniatus Poey. 1863 Polymixia lowei Gunter, 1859 Leprdopus sp (see Nakarnura & Parin 1993) Ze~dae Tr~chluruslepturus Linnaeus, 1758 Zenopsis conchifera (Lowe. 1850) Scornbndae Gramm~colepididae Auxls thazdrd (Lacepede, 1800) Xenoleprdrchthys dalgle~shiGilchnst, 1922 Sarda sarda (Bloch. 1793) Caproidae Scornberjaponicus Houttuyn. 1782 Antigonla capros Lowe, 1843 Centrolophidae Macroramphosldae Centroloph us sp. lMacroramphosus scolopax (Linnaeus, 1758) Ariommatidae ~\~otopogonfernandezianus (Delfin, 1899) Ariomma bondr Fowler, 1930 Dactylopteridae Strornateidae Vactylopterus volilans (Llnnaeus, 1758) Peprrlus paru (Llnnaeus, 1758) Scorpaenidae Bothidae Hellcolenus lah~lleiNorman. 1937 Cithanchthys cornutus (Gunther, 1880) Pont~nusrathbuni Goode & Bean, 1896 Etropus longlrnanus Norman. 1933 Setarches guenthen Johnson. 1862 Parallchthys rsosceles Jordan, 1890 Penstedildae Paralichthys patagonicus Jordan. 1889 Peristedron altiprnne Regan. 1903 Molidae Peristedlon sp Mola mola (Llnnaeus. 1758) Table 2. Absolute frequency of occurrence (AFO), slzes, bottom temperature and depth ranges of occurrence and relative abundance per depth of all identified bony fishes caught in 4 bottom cruises by the RV 'Atldntico Sul' in 1986 and 1987. Cruises: WS, winter-south 1986; LN. late winter-north 1986; SS, late summer-south 1987; AN, autumn-north 1987. Habitat: b, demersal-benthonic;d, demersal-pelagic; m, pelagic and mesopelagic

Species AFO Mean Mean Length Depth Bottom temp. Percentage of catch by weight Percentage of catch Habitat catch weight range (cm) range (m) range ("C) for depth range: by weight for cruises: (kg h-') (g) Min. Max. Min. Max. Min. Max. 120- 180- 250- 350- 450- WS LN SS AN

Merluccius hubbsi 37 1.045 78 8 48 120 490 6.8 17.0 12 31 33 17 7 50 13 31 6 d l Zenopsis conchifera 34 1.894 150 5 56 120 334 10.1 17.0 12 13 74 22 27 16 35 d Synagrops spinosus 33 0.062 15 6 14 129 401 6.8 17.0 31 30 26 12 67 7 21 5 d Polyrn~xlalowei 29 1.468 50 7 23 152 490 - 16.6

(Table continued on next page) Table 2 (continued)

Mean Mean Lenglh Depth Bottom lemp Percentage of catch by weight Percentage of catch Hab~tal catch weight range (cm) range (m) range ("C) for depth range: by welyht for crulses: (kg h-') (g) Min. Max Min. Max. Mm Max. 120- 180- 250- 350- 450- WS LN SS AN - -- Nolopogon fernandezianus 13 87 Pontinus rathbunr 64 36 Priacanlhus arenatus 1 99 < 1 Lophola lil~rsvilladi 33 20 47 Pnstipomoides freeman; 70 30 Decaplerus tab1 24 76 Hoploslelhus occidentalis 92 8 Synchiropus agassizii 13 87 Setarches guentheri 7 14 79 Prionolus punctatus 100 Pikea rosa 86 14 Mola mola 4 1 59 Pseudopercis spp. 100 Sardasarda 100 Caulolatilus chrysops 81 19 Cookeolus japonic~~s 100 Symbolophorus barnardi 2 98 Naucrates ductor 58 4 2 Chlorophthalm~rsagassizi 27 73 Stomias affinis 100 Diaphus effulgens 100 Bregmaceros atlanticus 4 6 54 Epinephelus fla volim batus 100 Paralichthys patagonicus 100 < 1 Gymnoscopelus piabjlis 100 Auxis thazard 100 Centrolophus sp. 100 Micropogonias furnieri 100 Percophis brasiliensis 100 Peprilus paru 100 Beryx splendens 100 Holanthias martrnicensis 100 Macruronus magellanlcus 100 Pomalomus sallatrix 100 Conger orbign yanus 100 Promelichthys promelhe~rs 100 Dactyloplerus volllans 100 Cynoscion jamarcensis 100 Perisledion altrplnnis 100 Dules aunga 100 Dysommina rugosa 100 Benlhocometes robustus 100 Melanoslomias niger 100 Malacocephalus laevis 100 Bellalor brachychrr 100 Neoscopelus macrolepidotus Etropus longimanus Ventrifossa on Brama brama

68 Mar. Ecol. Prog. Ser

at 50 to 120 m depth (Capitoli & Haimovici 1993).The below 214 m depth. Total length ranged from 20 to congeneric species Synagrops bellus occurred 16 37 cm (Fig. 3H). On the shelf coastal waters it feeds on times, in the same depth and temperature ranges as shrimps, crabs and to a lesser degree on fish. S. spinosus, but was more abundant in deeper waters. Helicolenus lahillei. This species is known to occur Their size distributions did not overlap in the samples from the coast of Santa Catarina State to northeastern (Fig. 3C). Argentina. Most of the specimens were juveniles, those Trichiurus lepturus. Distributed worldwide in tropical over 23 cm long were caught mainly in winter and some and warm-temperate waters, the cutlassfish was found of the females were ripe (Fig. 31). Seldom caught on the mainly on the outer shelf. Mean weight was 375 g and shelf, this is one of the most abundant demersal species total length varied between 27 and 143 cm but most on the break and upper slope. It is rather abundant in fishes were longer than 70 cm (Fig. 3D). Caught in all the Rio de la Plata Front over 100 m deep (Otero et al. cruises, the cutlassfish was more abundant in the south, 1982) where the larger specimens prey upon small and during the summer. Large adults caught on the benthic and fishes (Migliore 1988). In the outer shelf fed mostly on Maurolicus muellen and study area it feeds mostly on myctophid fishes, euphausiids. Spawning specimens were found during and anomuran (Munida spp.). May and September cruises, when specimens from the Scomber japonicus. Chub is a cosmopoli- shelf were still maturing (Martins 1992). tan species, inhabiting warm and temperate waters. It Polymixia lowei. The beardfish is distributed in the was mainly caught in the south in winter below 180 m western Atlantic from Uruguay to New Jersey, USA. It depth. The total length ranged from 17 to 23 cm in occurred throughout the surveyed area, but was more winter, with a mode of 20 cm. In summer, its size common in the northern region. In the warm season ranged from 12 to 26 cm, the mode being 16 cm cruises 2 modal groups, l l cm and 17 cm long, were (Fig. 35). This mackerel feeds on euphausiids and observed (Fig. 3E). No ripe or maturing specimens (Schwingel 1991). A single migratory stock were found. P lowei feeds mainly on small demersal living between Rio de Janeiro and Argentina was fishes such as Bregmaceros atlanticus and benthic proposed by Seckendorff & Zavala-Camin (1985) but decapod crustaceans. morphometric differences were found by Perrota et myrsitops lepidopoides. This gempylid fish is limited al. (1990) when comparing fishes from southern Brazil to the Atlantic and Pacific coasts of southern South and the Mar del Plata region. America. More frequent in the north, it presented 2 Sciaenoides bergi. This species is known to occur modal groups of 23 and 28 cm long in winter and from Rio de Janeiro to Argentina, being more frequent summer, respectively (Fig. 3F). In winter and spring it in the south. This is a temperate-water benthic inverte- was found to feed on young Engraulis anchoita and brate feeding species common on the Argentinean and euphausiids on the shelf (Schwingel 1991, based on 11 Uruguayan shelf (Fernandez & Norbis 1986). examples 72 to 248 mm long). Ripe females over 21 cm Coelorinchus marinii. This macrourid occurs in the were observed in November and March. southwestern Atlantic from southern Brazil to Antarc- Trachurus lathami. This jack mackerel ranges from tica (Cohen et al. 1990). It was frequent below 350 m the Gulf of to Argentina. Rather abundant and depth in winter in the entire area studied. Mean occasionally landed by or mackerel purse- weight was 58 g and total length ranged from 12 to seiners along the coast of southern and southeastern 34 cm (Fig. 3K). Some mature females over 250 mm Brazil, it was caught at 19 stations up to 180 m deep, were taken in all cruises. Its diet includes benthic representing 21.03 % of the catch and being more com- crustaceans and polychaetes. mon towards the north. Length ranged from 9 to 20 cm Paralichthys isosceles. This occurs from Rio (Fig. 3G). In winter and spring it preys mainly upon de Janeiro to northern Patagonia. This species is typi- euphausiids and copepods (Schwingel 1991). cal of the outer shelf in the region throughout the year. Urophycis mystacea. This is a type of hake confined Specimens smaller than 18 cm were found only in to the waters from Argentina to Rio de Janeiro. It was autumn (Fig. 3L). It preys upon small fishes, benthic more frequent in the south in both winter and summer- crustaceans and cephalopods. Spawning seems to autumn cruises. Most of the fish caught were immature occur on the outer shelf in summer. specimens, a few maturing females over 30 cm long Polyprion americanus. The wreckfish is found in being observed in May and July. Its food consists of the Atlantic, Mediterranean and Indian , and benthic crabs and shrimps but also small demersal- waters around New Zealand. This is the only commer- pelagic fishes and cephalopods. The congeneric spe- cially fished teleost on the upper slope in the study cies Urophycis brasiliensis has the same geographical area, where it is fished with a hand l~neon rocky distribution, being more abundant in shallower waters, bottoms (Wahlrich & Peres 1990). This large fish had a where it is fished by trawlers. It occurred in 8 hauls mean weight of 9.4 kg, and its total length ranged from rlaimovici et al.: Demerse11 bony fish off southern Brazil 65

56 to 113 cm (Fig. 3M). It occurred at all fished depths temperatures over 15.8'C. Sizes ranged from 11 to in temperatures varying from 6 to 16.2"C. Reproduc- 50 cm (Fig. 3Q). Most specimens taken were juveniles tion seems to occur in the cold season. l? americanus but some adults were caught in the winter. feeds on fishes such as Merluccius hubbsj, Helicolenus Umbrina canosai. A migratory species between lahillei and Urophycis mystacea, the crab Cheaceon Argentina and southern Brazil, where it is intensively notialis and the squid Illex argentinus. fished by trawlers, this sciaenid is found in small quan- Genypterus brasiliensis. Known to occur from Rio tities up to Rio de Janeiro. In the survey it was caught de Janeiro to Argentina, this fish was confused with below 165 m depth and at temperatures over 15.2"C. G. blacodes, found from Uruguay to the southern tip of Sizes ranged between 10 and 40 cm (Fig. 3R). It was South America. This highly appreciated gadiform was more frequent in both northern-area cruises in May caught in small numbers between 128 and 334 m deep, and September. Adult spawners were observed in the presenting a mean weight of 1.402 kg and a total winter cruise at 130 m depth at 31's. Specimens over length from 37 to 80 cm. Specimens smaller than 60 cm 25 cm were not common at depths over 75 m but some were found only in summer. It was more abundant in commercial catches of larger specimens have been winter and in the south. Only immature specimens reported (Haimovici 1982). U. canosai is a long-living were caught. The few stomachs observed contained and slow-growing species that spawns in spring and benthic macrocrustaceans and unidentified fishes. feeds on benthic invertebrates (Haimovici & Reis 1984, Lophius gastrophysus. The blackfin goosefish lives Haimovici & Cousin 1989, Hairnovici et al. 1989a). in waters between Rio de Janeiro and Argentina. A Pagrus pagrus. The is an Atlantic and few specimens measuring 23 to 64 cm and with a mean Mediterranean species (Manooch & Hassler 1978). A weight of 1.183 kg were caught in 13 tows, from 180 to few specimens measuring from 11 to 50 cm total length 300 m deep and from 11.5 to 17.0 'C. and 705 g mean weight occurred in 6 hauls at depths Malacocephalus occidentalis. This is a benthic < 185 m and bottom temperatures from 15 to 17 "C. It macrourid species found along the slope of both migrates to southern Brazil in winter together with cold margins of the South Atlantic (Cohen et al. 1990). It waters on the mid-shelf (Yesaki & Barcellos 1974, was caught mostly at depths >350 m. Total length Haimovici 1991). P pagrus feeds on a wide variety of ranged from 15 to 39 cm (Fig. 3N). M. occidentalis was benthic and and invertebrates (Capitoli more abundant in the north. Ripe females over 35 cm & Haimovici 1993). long were found in July. It feeds on benthic macro- Porichth ys porossissimus. Known to occur from crustaceans, myctophid fishes and cephalopods. Argentina to Rio de Janeiro, the midshipman was Ariomma bondi. The silver-rag lives in the Atlantic taken between 130 and 212 m deep. It was relatively Ocean, ranging from Maine to Uruguay in the western abundant in only 2 hauls, one in winter at 178 m and Atlantic. It occurs in large schools on mud or sand the other in summer at 134 m. bottoms of the outer shelf, and feeds on small benthic- Diaphus dumerilii. A common and abundant meso- dwelling , mainly crustaceans (Fischer 1978). It pelagic tropical species widely distributed in the was present in 24 hauls, from 129 to 380 m, but abun- Atlantic Ocean, it probably consists of a number of dant only in 1 at 250 m depth near the Cape of Santa populations. In the southwestern Atlantic adults not Marta Grande. Its mean weight was 49 g and total yet sexually mature occurred near the continent in length ranged from 6 to 19 cm (Fig. 30). Larger speci- relatively cold waters under steep thermoclines and mens were taken in spring and maturing females over were considered an 'expatriate population' (Hulley 15 cm in winter. 1981). It measured 4 to 13 cm long with a mean weight Mullus argentinae. The goatfish is known to occur of 3 g. It was the most frequent myctophid in the from Rio de Janeiro to Mar del Plata. It was caught on survey, occurring in 15 hauls from 197 to 587 m deep the outer shelf and was more common in the northern and from 4 to 15.7 "C. Undersampled by our gear, it winter cruise. The mean weight was 65 g and total was found in the stomach contents of several fishes and length varied from 11 to 22 cm (Fig. 3P). It feeds on seems to be very abundant and important in the benthic invertebrates. trophic relations on the slope. Catches up to 15 t haul-' Cynoscion guatucupa syn. Cynoscion striatus. This were recorded off Uruguay and northern Argentina weakfish (for taxonomic status see Figueiredo 1992) (Hulley 1981). The congeneric species D. effulgens occurs from Rio de Janeiro to Argentina, and is an im- was caught in only 2 hauls below 458 m depth. portant commercial species in the coastal trawl fishery Argentina striata. Found along the western Atlantic of southern Brazil, Uruguay and Argentina (Haimovici from Nova Scotia to Uruguay, this studied argentine et al. 1989b, Vieira 1990). It is a shelf species which was was taken in small numbers between 150 and 450 m relatively abundant in many of the hauls < 165 m depth, depth, but more frequently up to 250 m deep in the and occurs mainly in winter in the south and at bottom northern region. 70 Mar. Ecol. Prog. Ser. 108: 59-77, 1994

Antigonia capros. The boarfish is a cosmopolitan tom temperature and latitude with the scores of the species in temperate and tropical waters, except in the hauls along the 4 axes are shown in Table 3. Depth and eastern Pacific. In winter only juveniles were taken, temperature were strongly correlated with Axis 1 in npe females over 15 cm having been caught in March. both seasons and to a lesser degree with Axis 2 in Boarf~sh occurred more frequently at temperatures summer-autumn. Latitude only correlated with Axis 4 over 12.5 "C and depths up to 250 m. It feeds mostly on in winter-spring. Species and stations simultaneously hypenid amphipods, euphausiids and small squid. ordered following DCA Axis 1 in both seasons are Most catches occurred in the northern spring and shown in Table 4. A more-or-less continuous sub- southern summer cruises. stitution of species was observed both in winter and Benthodesmus elongatus. The frostfish is found in summer-autumn with increasing depth and decreasing subtropical and temperate waters of the southern bottom temperature, probably due to the lack of dis- hemisphere. Frostfish were more abundant in July in continuities in the bottom topography and morphology the north and in summer in the south, where larger in the trawling areas. specimens were more frequent. A few examined stom- Depth ranges. Total teleost mean catch decreased ach contents contained euphausiids and myctophids. 6-fold along the depth gradient, from 170.9 (120 to Priacanthus arenatus. The bigeye is known to occur 179 m) to 26.3 kg h-' (450 to 587 m). The number of from Canada to northern Argentina. It was caught in species decreased from 61 to 27 in the same depth 4 hauls from 176 to 587 m deep, and from 4 to 16.3 "C. range. Demersal-pelagic catches decreased sharply Its mean weight was 1.586 kg and total length ranged below 180 m depth with a partial recovery due to a from 21 to 53 cm. Most were caught in a summer haul large single catch of Ariomma bondi between 250 and at 188 m depth and 16.3 'C at 31" 09' S. 349 m. The demersal-benthonic catches decreased Maurolicus muelleri. This small mesopelagic fish is little with depth, ranging between 29.4 and 21.4 kg h-'. common along the continental slope of all oceans up The total number of species decreased slowly from to the 400 m isobath (Weitzman 1986). It was found at 61 to 45 down to 350 m depth and to 26 and 27 in the only 8 stations and measured from 4 to 5 cm, but was last 2 depth ranges, showing a similar pattern for frequent in the stomach contents of several demersal- demersal-pelagic and demersal-benthic species. The pelagic fish caught and appears an important species in mean number of species per haul decreased more the food chains in the study area. The species spawns in gently, from over 14 (to 250 m deep) to 8.1 (below midwater on the shelf break, mainly from autumn to 350 m) (Table 5). spring, eggs and larvae being retained in the front be- Latitudes and seasons. Mean total catches ranged tween tropical waters of the Brazil Current and colder from 74.4 to 97.5 kg h-', and total number of species and less saline coastal waters, and carried over the shelf varied from 53 to 67 per cruise, both values being by the partial upwelling of subtropical waters (Weiss et higher in winter cruises (Table 5). Mean number of al. 1988).Frequent and abundant in plankton samples. species ranged from 10.8 to 14.2. The catches of its stock size was estimated from egg counts as being demersal-pelagic bony fishes differed little between over 1600 t (Weiss et al. 1988). It feeds on planktonic seasons, ranging from 54.4 to 66.8 kg h-', being crustaceans such as copepods and hyperiid amphipods. slightly higher in both northern cruises; the number of species was lower, 19 compared to 23 and 24, in the southern cruises. Demersal benthlc fish catches in win- Distribution pattern, relative abundance and ter and spring (38.5 to 36.9 kg h-') were more than number of species 2-fold the catch in summer and early autumn (11.8 to 16.0 kg h-') but the number of species was sinular, Eigenvalues of Axes 1 to 4 in seasonal DECORANA ranging from 28 to 32. The difference was due mostly runs and correlation coefficients between depth, bot- to some deep-water species such as Polyprion ameri-

Table 3. Eigenvalues of Axes 1 to 4 in a detrended correspondence analysjs (DCA) and correlation coefficients between depth, bottom temperature and latitude with the scores of fishery hauls on Axes 1 to 4 ('significant at 5 % probability level)

Winter and spring cruises Summer and autumn cruises Axis 1 Axis 2 Axis 3 Axis 4 Axis 1 Ads 2 Axis 3 Axis 4

Eigenvalues 0.66 0.35 0.19 0.13 Depth 0.89' 0.02 0 09 0.07 Bottom temperature 0.84 ' 0.01 <0.01 0.08 Latitude 0.09 'US8C 3 - 3 i" 3 . c 300'8>'U OOP c c + Do0'8 > 'U0Sp -NN- m3N3 -m-- N- ~.~'~>'uIcP- NNN-~+~--N---+m c 300'8>'U 11s 3 NcN er e N- 3,0'8 > 'W 09P + -+m - c 3.0'8 > 'U 06P m - m 7 .-. V, 4 U) 9a S a, .- U 2 U m a 2 2 m z 2 F .S 5' 3 m 3 7: g E c 5 D aI Q

L. a P 5 CV, W 2

er N 488 m, 4.8"C c. er C+ r 452 m. 6.5 "C r rr rh)r 587 m.4.0°C rr rcr h) r 422 m, 8.5 "C r r h) 348 m, 8.0°C + r r~ rr 479 m, 4.9"C r r rN 450 m, 6.0 "C r h) rrW 304 m, 10.O°C rr r - r r 401 m, 6.8"C r 188 m, 16.3 "C CH h) CL r 334 m,12.0°C C 196 m, 15.7 "C CL rr r CL C 301 m,10.1 "C r Wr rrrrw r ww r rrr~N 214 m. 15.0°C r r rr+ CL c. rNNrrN wr 186 m, 16.3"C r N +W r r rr N W r 291 m, 14.0°C er r r r N N 3 - r C 233 m, 13.0°C r r ~r c. c. r WN rh) 197 m, 15.7 "C

r r C N rrrr N r r h, r 183 m, 16.3"C - r r CL r N rrr r C W 285 m, 14.5"C

W r rr mr r r r CL 229 m, 15.5"C

J r h) r rrr r +C W 200 m. 15.7 "C

ra h)rr r a CC rh) h)N h) 130 m, 17.0°C

C rr CL rrN h) r 164 m, 15.7"C

rN r W r r r r rr 128 m, 17.O0C

N r r r rrr r N p3 150 m, 16.5"C

rw W rwrr N rr c. r 144 m, 17.0°C

WNrNW NW- rNr rN r rN r 134 m, 16.0°C

N VI + h) H r 140 m, 15.8"C Haimovici et al.: Demersal bony fish off southern Brazil

Table 5. Catch (kg h-') and number of teleost species per cruise and depth range in a bottom trawl survey off southern Brazil during 1986 and 1987

Cruise Depth range (m) Ju11986 Sep1986 Mar 1987 May1987 120-179 180-249 250-349 350-449 450-587 Winter Spring Summer Autumn South North South North

No. of hauls Total bony fish catches Mesopelagic species Demersal-pelag~cspecies Demersal-benthon~cspecies Total no. of species Mesopelagic species Demersal-pelagic species Demersal-benthonic species Mean no. of specles per haul

20 canus, Helicolenus lahillei and Coelorinchus marinii. Few mesopelagic species were caught, mainly myc- 18 n tophids, and were more abundant in both southern cruises. Most species occurred in both winter and summer- autumn cruises (Table 2) but, because the study area is in the western boundary of the Subtropical Conver- gence, some seasonal pattern in the bony fish fauna is expected to occur. To investigate this possibility, the species were classified according to their relative abundance in the winter and summer-autumn cruises (Fig. 4). Species were grouped into: 'cold season species', those in more than 75 % of the catches in the winter-spring cruises; and 'warm season species', those in more than 75 % of the catches in summer-autumn cruises; the rest were included in a 'resident species' group. Overall, 42.5% of the catches were composed of 42 cold season species, and 19 warm season species amounted to 1.8% of the catch. A total of 32 resident species represented 55.7%. To account for bottom depth, species were arranged in 3 groups: (1) those found above 250 m depth, (2) those found below 350 m depth, and (3) those caught at intermediate depths or over a wider depth range. Warm season species were of little importance in all 3 ranges (2.4, 3.3 and 3.3% of the catch) and were more numerous on the outer shelf. Resident species were more abundant and numerous at <250 m (69.9%), second in intermediate depth (42.1 %) and scarce at >350 m (4.2%). The opposite Depth ronpes was observed for the cold season species (27.7%, 54.6% and 95.0% respectively in each depth range) Cold seoson 'ypsih;i Worm season species species which were almost as numerous on the outer shelf as at greater depth. With increasing depth, the relative abundance of species that occur year-round decreases, Fig. 4. Catches and number of teleost species per depth range meanwhile it was higher for fishes that occur mostly in classified according to their relative abundance in the winter- spring (cold) and summer-autumn (warm) cruises (for further winter, the warm season species having little quantita- details on the classification see text) tive importance in the catches. 74 Mar. Ecol. Prog. Ser. 108: 59-77, 1994

DISCUSSION is probably caused by the stronger convergence shift phenomena near the bottom than the surface, as the The southern Brazilian coast is on the boundary Brazil Current runs southward all year in the upper between subtropical and warm temperate regions. layers (Fig. 2). Figueiredo (1981), studying the continental shelf fish Depth as the main ordination factor of marine fish fauna, set the limits of the transitional zoogeographic assemblages is well documented (Lleonart & Roe1 Argentinean Province at Cabo Frio (21" S) and Valdes 1984, Longhurst & Pauly 1987, Bianchi 1991, 1992). Peninsula (42" S), between the Caribbean and Pata- Physical characteristics of the water masses (tempera- gonian provinces (Palacio 1982). The Argentinean ture, oxygen, salinity) as well as other factors such as Province has a low proportion of endemic fish species, bottom type, light intensity, and pressure are mostly ca 10%, characterized by high tolerance to tempera- related to depth (Bianchi 1991, 1992), but the way in ture and salinity variations (Figueiredo 1981) as a con- which these factors affect the fish distribution pattern, sequence of the influence of the seasonal shift of the and the intensity of their effects, are difficult to assess Subtropical Front and the (seasonal) upwelling of cold and our data do not support further analysis. waters off southeastern Brazil (Matsuura 1986). Catches and species numbers in the 2 southern In this survey, species endemic to the Argentine cruises were compared with catches in 2 surveys on Province, e.g. Umbrina canosai, Urophycis brasiliensis, the inner shelf between 10 and 120 m in the same Mullus argentinae, Paralichthys isosceles, and Cynos- seasons in April 1983 and August 1983 (unpubl. data). cion guatucupa, were found mostly on the outer shelf, Catches from the shelf were divided by 2 as the net and were more abundant in shallower waters. Many used on the shelf had a footrope of 52.9 m, approxi- species with a wide Western Atlantic distnbution, mately twice the length of the one in the present study stretching from northern Argentina to the northern (Fig. 5). In winter greater catches were observed on the hemisphere, in some cases up to Canada, are found shelf between 40 and 60 m, in the core of the inner along the upper slope, e.g. Trachurus lathami, Scomber branch of the Malvinas/Falkland Current. Demersal- japonicus, Anomma bondi, Polymixia lowei, and pelagic species were more abundant and therefore Polyprion americanus. In deeper waters species with a associated with the higher winter pelagic . wider geographic distribution, even cosmopolitans, are A second, much smaller, peak was found on the upper found, e.g. the benthic and demersal macrourids, trichi- slope between 250 and 350 m, mostly composed of urids, mesopelagic myctophids, Maurolicus muelleri Polyprion americanus and Ariomma bondi. The high- and Zenopsis conchifera. Species from cold temperate est mean number of species per trawl was found in the waters abundant in southern Argentina were scarce in shelf break and included both resident and northward this survey; only Merluccius hubbsi was numerically winter immigrant species of the shelf and slope. In abundant. Except for some demersal-benthonic species summer, the shelf peak was lower, in the 20 to 60 m on the outer shelf, most abundant species were demer- depth range, and a there was a shelf break peak com- sal-pelagic or hard bottom species. posed mainly of Trichiurus lepturus and Trachurus Our results show a weak latitudinal gradient in the lathami. This shelf break peak is probably associated composition of fish fauna. This is expected as there are with the vortices and the partial upwelling of sub- no geographic or hydrographic barriers and the ampli- tropical waters (Podesta 1990, Lima 1992). Many of the tude in the bottom temperatures between north and demersal-pelagic species of wide geographic distribu- south extremes of the study area in each season was tion represented by adults in the survey were sexually small. Instead, the north-south shift of the western mature. Egg and larval survival of these species may boundary of the Subtropical Convergence appears as be favored by the upwelling and transport from the the main factor responsible for seasonal changes in slope to more productive waters of the shelf, as sug- species abundance. Variation in demersal-pelagic gested for Maurolicus muellen by Weiss et al. (1988). species abundance was small, as at these latitudes the Despite the lower catches compared to the inner Brazil Current is present along the slope year-round shelf, the number of species was high on the shelf and water temperature varies little. Colder water break (Fig. 5). This may be due to a higher variety of demersal-benthonic slope species were more affected, soft and consolidated substrates and the overlapping probably moving southward or to deeper waters in the of different water masses along the water column. A warm season when the Convergence is further south. sharp decrease in the number of species was observed With increasing depth, the demersal-benthonic bony at depths greater than 350 m and may be associated fishes that move northward are more abundant in with the generally poor benthic invertebrate fauna of winter, while no seasonal fluctuation was observed for the slope found by Capitoli & Bonilha (1991). the demersal-pelagic fauna, which was more abundant Catches of demersal-pelagic species under the core on the outer shelf compared to offshore. This situation of the Brazil Current in the upper slope were very low Haimovici et al.. Demersal bony fish off southern Brazil 75

Winter-spring cruises

Coastal Inner shelf Shelf break Upper slop , , ., .. ... ; *. Numberof leleost .'*../ species

Midpoint depth ranges (m)

Summer-autumn cruises 700 60 Coaslal Inner shelf Shelf break Upper slope 600 - 50 Number of leleosl - .,.'*,~... species -- 500- .,' .. .-YICJ !c -40 2 00 ...... _...__; 400- 4 U VI r; Dememl pelagic U . .. ,' , -30 4 z m- ... catches L c- c m -20 g 200- . ....-' Fig. 5. Relative abundance (kg :. ....-.'.' 5 h-') and number of teleost spe- benlhic calcher -10 cies per depth range In the cold and warm season cruises 0 off southern Brazil (see text for 10 30 50 70 100 150 200 300 400 520 details) Midpoint deprh ranges (m)

and, at least in winter and spring, the short fin squid Acknowledgements. The authors thank C. Borzone for his Illex argentinus was rather abundant (Haimovici & help with the multivariate analysis and J. P. Castello for his Perez 1991a). Ommastrephid squids may be an impor- comments on the hydrographic description. B. A. G. Lourerio drew the figures. The research was funded by the Banco do tant part of the demersal-pelagic nectOn of the upper Brasil Research Fund (FIPEC) and grants to M.H. from the slope. Amaratunga (1983) and Santos (1992) showed Brazilian Research Council (C~pq). the importance of I. argentinus in the food chains of that region. The only bottom fish resources of the shelf break and LITERATURE CITED upper slope are the migratory school Galeorhi- Amaratunga, T (1983). The role of Cephalopoda in the nus galeus in winter and Polypnon americanus (Vooren . In: Caddy, J. F. (ed.) Advances in et al. 1988), both more efficiently fished with bottom assessment of world cephalopod resources. FAO Fish. longline, the king crab Chaceon notialis (syn. Geryon tech. Pap. 231: 379-415 quinquedens) (Lima & Lima 1991) and the short fin Angelescu, V., Prenski, L. B. (1987). Ecologia trofica de la squid Illex argentinus (Haimovici & Perez 1991a). Bony merluza comun del Mar Argentino (Merlucciidae, Mer- luccius rnerluccius hubbsj]. Parte 2. Serie Contribuciones fish from the shelf break and upper slope do not No. 561. INIDEP. Mar del Plata appear to sustaln a large commercial bottom trawl Benvegnu-Le, G. Q (1978) Distnbulqdo dos pelxes teleosteos fishery but the catches of demersal-~elaaic. " small bonv marinhos demersais na plataforma continental do Rio fish, e.g. Anomma bondi,Trachurus lathami, Scomber Grande do Sul. Ph.D. thesis, Universidade de SBo Paulo Blanchi, G. (1991). Demersal assemblages of the continental japonicus, and Trichiurus lepturus, all feeding mainly shelf and slope edge between the Gulf of Tehuantepec on , were considerable in some hauls. (Mexico) and Gulf of Papagayo (Costa Rica). Mar. Ecol. Their midwater trawl-fishing potential is still unknown. Prog. Ser. 73: 121-140 7 6 Mar. Ecol. Prog. Ser. 108: 59-77, 1994

Bianchi, G. (1992). Study of the demersal assemblages of the cion de la merluza Merluccius hubbs~en el sur de Brasil continental shelf and upper slope off Congo and Gabon, Frente Marltimo, Montevideo 14- 33-40 based on the trawl surveys of the RV 'Dr Fndtjof Nansen' Haimovici, M, Pereira, S. D, Vieira, P. C (1989b). La pesca Mar Ecol. Prog Ser 85: 9-23 demersal en el sur de Brasil en el penodo 1975-1985. Capitoll, R., Bonilha, L. E. (1991). Comunidades bentonicas. Frente Maritimo, Montevideo 5. 151-163 In. Vooren, C. M. (ed ) Projeto Talude. FIPEC Flnal Report, Halmovici, M., Perez, J. A A. (1991a) A pesca de cefalopodes FURG, hoGrande, p. 79-92 em quatro cruzeiros de prospeqao pesquelra demersal na Capitoli, R , Halmovicl, M. (1993). Dieta alimenticla del plataforma externa e talude continental do sul do Brasil besugo Pagrus pagrus en el extremo sur de Brasll. Frente entre Chui (34"30' S) e o Cabo de Santa Marta Grande Mantimo, Montevideo 14. 81-86 (28O40'S). 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This article was submitted to the edltor Manuscript first received: October 15, 1993 Revised version accepted: February 2, 1994