ABSTRACT The biology and ecology of southwestern Atlantic loliginid squids have been intensively researched in the last few decades, mostly off the Brazilian southern coast. However, information gathered by scientific research cruisers, either past or recent, is limited. Three species of loliginid squids - the warm-tempered Doryteuthis sanpaulensis (Brakoniecki, 1984), plus the tropical D. pleii (Blainville, 1823) and Lolliguncula brevis (Blainville, 1823) - were sampled along 16 degrees of latitude on the southwestern Atlantic (22-38°S). The samples were obtained mostly from oceanographic surveys, but also included squids caught by commercial fisheries, and a few specimens from museum collections. Squid response to abiotic variables, morphological variation and circadian behaviour were surveyed in detail. Doryteuthis sanpaulensis can be divided into at least six distinguishable geographical groups, which do not form a cline. In contrast, D. pleii can be divided into only two morphological groups that are very similar. Doryteuthis spp. were heterogeneously distributed on the shelf, whereas L. brevis was confined nearshore. Our data extended the southernmost distribution range of D. pleii by at least nine degrees of latitude, owing to specimens obtained at ~38°S (Mar del Plata, Argentina). Small, immature D. sanpaulensis were sampled inside the Patos Lagoon estuary (~32°S). The morphologically similar Doryteuthis spp. apparently avoid direct competition by concentrating at different depths, displaying different thermal preferences, and inverse circadian levels of activity. The information reported herein may be regarded as a “snapshot” of the ecology of sympatric squids in a marine environment that has not been deeply affected by climate change.

Aspectos biológicos do peixe-galo-de-profundidade, Zenopsis conchifer, foram estudados a partir de 839 peixes amostrados na pesca comercial de arrasto de profundidade (até 526 m) no sul do Brasil entre 2002 e 2003. As amostras incluíram peixes entre 101 mm TL e 15 g até 640 mm TL e 2.952 g. A proporção sexual foi próxima à paridade na classe de tamanho de 150 mm TL e entre 300-350 mm TL, sendo que as fêmeas predominaram nas demais classes. A atividade reprodutiva apresentou um pico durante o inverno. O tamanho de primeira maturação (TL50) nas fêmeas foi de 311 mm TL. Os comprimentos corporais e a maturidade sexual aumentaram com a profundidade, sugerindo que os maiores exemplares se concentram águas profundas.

Biological aspects of sailfin dory, Zenopsis conchifer, were studied from 839 individuals obtained from deep-sea commercial bottom trawling off southern Brazil at depths up to 526 m in 2002 and 2003. Samples included fish from 101 mm Lt and 15 g up to 640 mm Lt and 2,9 g. The sex-ratio was 50% at 150 mm Lt and between 300-350 mm Lt, with females outnumbering males in the remaining size classes. Reproductive activity seems to peak between July and August (austral winter). Size at attainment of 50% maturity (Lt50) was 311 mm Lt in females. The mean length and maturity of the specimens increased with depth, suggesting that larger fish concentrate in deeper waters.

A carcass of a giant squid Architeuthis sp. was found afloat off Southern Brazil (28°05'S, 45°35'W) on 29 August 1999. The specimen was a mature female of 116 cm mantle length and had arms incomplete and tentacles missing. The specimen was morphologically similar to those previously described for the Southwest Atlantic, but a few peculiarities were found on the shape of the fins, head and the cross-section and length of ventral arms. Spermatophores were found embedded within the skin of the left ventral arm, at around 60 cm from the mouth, and could be traced to the core of the arm, radiating nearly four centimeters from the point of entry. This was the third record of Architeuthis in Brazilian waters and the eighth in Southwest Atlantic when the specimen was found.