Manuel Haimovici

Cephalopods in the diet of marine mammals stranded or incidentally caught along southeastern and southern Brazil (21–34°S)

Abstract Cephalopod remains found in 286 stomach contents of 13 species of odontocetes (Pontoporia blainvillei, Lagenodelphis hosei, Sotalia fluviatilis, Stenella frontalis, Steno bredanensis, Tursiops truncatus, Delphinus sp., Globicephala melas, Orcinus orca, Pseudorca crassidens, Kogia breviceps, K. sima and Physeter macrocephalus) four species of pinnipeds (Arctocephalus australis, A. gazella, A. tropicalis and Mirounga leonina) were identified and measured. The stomachs were collected from stranded or incidentally caught marine mammals from Rio de Janeiro to Parana states (21–26°S) and Rio Grande do Sul (29–34°S), between 1985 and 1998. Twenty-five species of 16 families of cephalopods were identified. Cephalopod prey were small to medium sized. The diversity of cephalopods as prey was lower for coastal marine mammals and increased in offshore species that fed on diverse oegopsin squids including both the fast moving muscular squids and the less mobile neutrally buoyant cephalopods. In common dolphins, ommastrephid and loliginid squids and the sepiolid Semirossia tenera, were all important in the diet. Loliginid squids were the most frequent cephalopod in the diet of six other species of dolphins and three species of fur seals. Loligo sanpaulensis was recorded in specimens from throughout the study area, whilst Loligo plei and Lolliguncula brevis were frequent in the northern area. Benthic octopuses were found only in the diet of bottlenose dolphin and franciscana. Pelagic octopuses, particularly Argonauta nodosa, were only relatively frequent in the stomach contents of franciscana. In the stomach contents of larger odontocetes, as well as in Southern elephant seals and SubAntarctic fur seals, squids of the families Ancistrocheiridae, Chiroteuthidae, Cranchiidae, Enoploteuthidae, Histioteuthidae, Lycoteuthidae, Octopoteuthidae, Onychoteuthidae and especially Ommastrephidae were found.

Diet and feeding of the cutlassfish Trichiurus lepturus in the Subtropical Convergence Ecosystem of southern Brazil

The diet and feeding of the cutlass¢sh Trichiurus lepturus were studied based on analyses of the stomach contents of larvae, juveniles, and adults collected along the continental shelf and shelf break oi southern Brazil, from the Cape of Santa Marta Grande (28836 0 S) to Chu|¤ (34845 0 S). The larvae and pre-juveniles with a total length of 55 cm were found to have fed almost exclusively on calanoid copepods, whereas juveniles (5 to 30 cm) fed on small zooplanktonic crustaceans such as Lucifer faxoni and Promysys atlantica. On the other hand, sub-adults (30 to 70 cm), fed on euphausiids, mainly Euphausia similis, and small ¢sh, mostly anchovy Engraulis anchoita. Adults (70 to 160 cm) fed on a wide range of larger prey, such as anchovy, sciaenid ¢sh, cephalopods and coastal shrimps, as well as euphausiids. The juveniles and sub-adults fed more intensively than adults during the warm-water season whereas adults fed more intensively during the cold-water season. Feeding activity was more intense at night, while cannibalism was more frequent during the warm season, when biological productivity was lower. Finally, diet diversity was higher in coastal waters, during the warm season. The abundance of cutlass¢sh oi southern Brazil may be explained by the fact that it is adapted to feed on a wide size-range of both pelagic and demersal prey.

Distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil subtropical convergence ecosystem

Abstract The distribution, abundance and biological interactions of the cutlassfish Trichiurus lepturus in the southern Brazil subtropical convergence ecosystem were studied from demersal trawl surveys conducted along the continental shelf and upper slope from Cape Santa Marta Grande (28 °36′S) to Chui (34 °45′S) between 1981 and 1987. Trichiurus lepturus was more abundant at bottom water temperatures of over 16 °C and in the 40–120 m depth range. From late spring to fall, juveniles of 5–30 cm total length ( TL ) were found in coastal waters, subadults ( TL 30–70 cm) mainly in inner shelf waters and adults ( TL > 70 cm) in coastal, inner and outer shelf waters. Higher catches of subadults and adults were found associated with thermal fronts in the western boundary of the Subtropical Convergence or with a shelf break upwelling observed in summer. The standing stock in a 58 000 km 2 shelf area estimated by the swept area method, ranged from 3066 t (±46% CI ) in September 1981 to 37814 t (±22% CI ) in January 1982. Correlation between occurrences of different size groups of cutlassfishes and other fishes caught in 250 bottom trawl hauls was analyzed. A positive correlation between cutlassfish and juvenile weakfish, Cynoscion guatucupa , was associated with similar spatial distribution but also indicated trophic competition.

Food and feeding of the short-finned squid Illex argentinus (Cephalopoda: Ommastrephidae) off southern Brazil

Abstract Diet and feeding habits of the short-finned squid Illex argentinus were studied from the analysis of 729 stomachs of juveniles, subadults and adults caught with trawls on the continental shelf and slope off southern Brazil (26 °35′S–34 °31′S) from 1981 to 1992. Food, in different degrees of digestion, was found in 363 stomachs (49.8%). Feeding activity occurred at day and night and seemed to be most intense at dusk and early night. The proportion of stomachs with food increased with size and sexual maturity. Fish occurred in 43.8%, cephalopods in 27.5% and crustaceans in 18.7% of the stomachs with food. Identified prey included the fish Diaphus dumerilii , Maurolicus muelleri and Merluccius hubbsi , the cephalopods I. argentinus , Loligo sanpaulensis , Spirula spirula , Semirossia tenera and Eledone gaucha and the crustaceans Oncaea media and Euphausia sp. The occurrence of fish increased with squid size, but both cephalopods and crustaceans were equally important for all sizes. Cannibalism was observed at all sizes. The overall low proportion of stomachs with food, the high rate of cannibalism and the low frequency of occurrence of crustaceans for the juveniles and subadults in all seasons, but particularly in the summer and autumn, may reflect a limited availability of food in the region. If this is true, the main nursery grounds for the spawners off southern Brazil are likely to be off the Rio de La Plata Front or in the offshore confluence between the Brazil and Malvinas Currents, where primary and secondary production is higher than off southern Brazil.

The Argentine short-finned squid Illex argentinus in the food webs of southern Brazil

Abstract Predation on Illex argentinus (Cephalopoda, Ommastrephidae) in southern Brazil (26°S to 34°S) was studied from its presence in contents of over 14 000 stomachs from 63 potential predator species including fishes, cephalopods, penguins and marine mammals. The size composition of I argentinus in the diet of their main predators was estimated using regression equations that relate mantle length and body weight to beak size. The short-finned squid was found in the diet of 32 species and appears to play an important role in the trophic relations along the upper slope and adjacent oceanic waters, where it was found in the diet of the swordfish Xiphias gladius, the tunas Thunnus obesus, T. alalunga and T. albacares, and the wreckfish Polyprion americanus. These five species stand for more than half of the landings from the upper slope demersal and oceanic pelagic fisheries in the region. On the shelf, where the dominant squid was Loligo sanpaulensis, Illex argentinus was only occasionally found in the diet of a few neritic predators. In southern Brazil, overall predation was more intense on subadults and adults of the winter-spring spawning group on the upper slope and oceanic adjacent waters, differently from its southern range along Uruguay and Argentina waters where the short-fmned squid is abundant on the shelf and is preyed upon mainly by the demersal fish assemblage.

Trophic relationships of the long-finned squid loligo Sanpaulensis on the southern Brazilian shelf

The diet and predators of Loligo sanpaulensis (Cephalopoda: Loliginidae) on the southern Brazilian shelf were studied by examining the stomach contents of 668 long-finned squid (12–184 mm mantle length) caught by bottom trawl and the stomach contents of 47 potential predators, including stranded penguins and marine mammals as well as fish and cephalopods caught with diverse fishing gears in the region. Of 313 long-finned squid stomachs containing food, fish occurred in 36.4% of stomachs, crustaceans in 23.3% and cephalopods in 6.4%. Identified prey included demersal fish, shrimps and conspecifics. Loligo sanpaulensis was preyed on by 31 of the 47 potential predatory species examined. The frequency of occurrence (FO) was high (>20%) in the stomach contents of La Plata dolphins Pontoporia blainvillei, penguins Spheniscus magellanicus, fur seals Arctocephalus spp., the benthic shark Mustelus canis and the benthic finfish Astroscopus sexpinosus and Percophis brasiliensis. It was less important (5–20% FO) for ...

Gillnet fisheries as a major mortality factor of Magellanic penguins in wintering areas

The incidental capture in fisheries is probably the main conservation problem affecting seabirds. While the capture of albatrosses and petrels on longline hooks is well-known worldwide, the bycatch of diving seabirds in gillnets is an overlooked conservation problem. During a winter coastal fishing trip, the capture of Magellanic penguins (Spheniscus magellanicus) was recorded in driftnet and bottom setnet fisheries for the first time in southern Brazil. The highest captures rates were found in driftnets, from 146.5 to 545.5 penguins/km² of net and a total of 56 dead penguins were recorded. In the bottom gillnet, a total of 12 birds were killed and the capture rates varied from 41.7 to 125.0 penguins/km² of net. Although preliminary, the results presented in this paper were consistent between sets. If we consider the magnitude of driftnet and setnet fishing fleets, and that most dead penguins were adults, the impact upon Magellanic penguin populations is probably significant.

The Path towards Endangered Species: Prehistoric Fisheries in Southeastern Brazil.

Brazilian shellmounds are archaeological sites with a high concentration of marine faunal remains. There are more than 2000 sites along the coast of Brazil that range in age from 8,720 to 985 cal BP. Here, we studied the ichthyoarchaeological remains (i.e., cranial/postcranial bones, otoliths, and teeth, among others) at 13 shellmounds on the southern coast of the state of Rio de Janeiro, which are located in coastal landscapes, including a sandy plain with coastal lagoons, rocky islands, islets and rocky bays. We identified patterns of similarity between shellmounds based on fish diversity, the ages of the assemblages, littoral geomorphology and prehistoric fisheries. Our new radiocarbon dating, based on otolith samples, was used for fishery characterization over time. A taxonomical study of the ichthyoarchaeological remains includes a diversity of 97 marine species, representing 37% of all modern species (i.e., 265 spp.) that have been documented along the coast of Rio de Janeiro state. This high fish diversity recovered from the shellmounds is clear evidence of well-developed prehistoric fishery activity that targeted sharks, rays and finfishes in a productive area influenced by coastal marine upwelling. The presence of adult and neonate shark, especially oceanic species, is here interpreted as evidence of prehistoric fisheries capacity for exploitation and possibly overexploitation in nursery areas. Various tools and strategies were used to capture finfish in seasonal fisheries, over rocky reef bottoms and in sandy littoral environments. Massive catches of whitemouth croaker, main target dermersal species of South Atlantic coast, show evidence of a reduction in body size of approximately 28% compared with modern fisheries. Fishery activity involving vulnerable species, especially in nursery areas, could mark the beginning of fish depletion along the southeastern Brazilian coast and the collapse of natural fish populations.

New molecular phylogeny of the squids of the family Loliginidae with emphasis on the genus Doryteuthis Naef, 1912: Mitochondrial and nuclear sequences indicate the presence of cryptic species in the southern Atlantic Ocean

The family Loliginidae Lesueur, 1821, is currently considered to include seven genera and approximately 50 species of neritic and coastal squids. These commercially important species occur in tropical and temperate coastal waters around the world. The taxonomy of the family has been revised a number of times in recent years, focusing in particular on genera such as Doryteuthis, Sepioteuthis, Alloteuthis, and Uroteuthis, which are represented by populations in the New World, Oceania, Europe/Africa, and Asia. However, no detailed phylogenetic analysis is available for the loliginids of the southern Atlantic, in particular the genus Doryteuthis. The present molecular study analyzed 81 loliginid taxa from around the world. The partial sequencing of the mitochondrial 16S and Cytochrome Oxidase I genes, and the nuclear rhodopsin gene revealed a number of important patterns, recovering the monophyletic status of the majority of the genera and revealing possible cryptic species in Doryteuthis plei D. pealei, Uroteuthis duvauceli and Sepioteuthis lessoniana.

Mitochondrial DNA reveals population structuring in Macrodon atricauda (Perciformes: Sciaenidae): a study covering the whole geographic distribution of the species in the southwestern Atlantic.

Abstract We investigated the genetic structure and diversity of M. atricauda, based on 266 specimens collected off the coast of southern Brazil and Argentina at seven locations, covering the whole geographic distribution of this species. A DNA sequence alignment of 904 base pairs of the mitochondrial Control Region revealed a total of 85 haplotypes. FST analyses suggest that M. atricauda does not comprise a single demographic stock. Two different genetic units are identified, which possibly are related to ecological adaptations of the species within its range. Genetic diversity, Bayesian analysis of population structure, and significant negative results for the D and FS tests indicate that M. atricauda populations have undergone recent expansion. The spatial distribution of genetic variation seems to be related to historical colonization from south to north, followed by expansion.