264 resultados para Southern Brazilian shelf
Resumo:
This contribution summarizes knowledge on the biology (population dynamics, reproduction, ecology) of 25 fish species from the Lower Amazon, Brazil, based on data from a Brazilian-German field project (IARA) and a review of the literature.
Resumo:
Water currents are vertically structured in many marine systems and as a result, vertical movements by fish larvae and zooplankton affect horizontal transport (Power, 1984). In estuaries, the vertical movements of larvae with tidal periods can result in their retention or ingress (Fortier and Leggett, 1983; Rijnsdorp et al., 1985; Cronin and Forward, 1986; Forward et al., 1999). On the continental shelf, the vertical movements of organisms interact daily and ontogenetically with depth-varying currents to affect horizontal transport (Pillar et al., 1989; Barange and Pillar, 1992; Cowen et al., 1993, 2000; Batchelder et al., 2002).
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Seasonal and cross-shelf patterns were investigated in larval fish assemblages on the continental shelf off the coast of Georgia. The influence of environmental factors on larval distributions also was examined, and larval transport processes on the shelf were considered. Ichthyoplankton and environmental data were collected approximately every other month from spring 2000 to winter 2002. Ten stations were repeatedly sampled along a 110-km cross-shelf transect, including four stations in the vicinity of Gray’s Reef National Marine Sanctuary. Correspondence analysis (CA) on untransformed community data identified two seasonal (warm weather [spring, summer, and fall] and winter) and three cross-shelf larval assemblages (inner-, mid-, and outer-shelf ). Five environmental factors (temperature, salinity, density, depth of the water column, and stratification) were related to larval cross-shelf distribution. Specifically, increased water column stratification was associated with the outer-shelf assemblage in spring, summer, and fall. The inner shelf assemblage was associated with generally lower temperatures and lower salinities in the spring and summer and higher salinities in the winter. The three cross-shelf regions indicated by the three assemblages coincided with the location of three primary water masses on the shelf. However, taxa occurring together within an assemblage were transported to different parts of the shelf; thus, transport across the continental shelf off the coast of Georgia cannot be explained solely by twodimensional physical factors.
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The Argentine sandperch Pseudopercis semifasciata (Pinguipedidae) sustains an important commercial and recreational fishery in the northern Patagonian gulfs of Argentina. We describe the morphological features of larvae and posttransition juveniles of P. semifasciata and analyze the abundance and distribution of early life-history stages obtained from 19 research cruises conducted on the Argentine shelf between 1978 and 2001. Pseudopercis semifasciata larvae were distinguished from other larvae by the modal number of myomeres (between 36 and 38), their elongated body, the size of their gut, and by osteological features of the neuro- and branchiocranium. Pseudopercis semifasciata and Pinguipes brasilianus (the other sympatric species of pinguipedid fishes) posttransition juveniles were distinguished by their head shape, pigmentation pattern, and by the number of spines of the dorsal fin (five in P. semifasciata and seven in P. brasilianus). The abundance and distribution of P. semifasciata at early stages indicate the existence of at least three offshore reproductive grounds between 42−43°S, 43−44°S, and 44−45°S, and a delayed spawning pulse in the southern stocks.
Resumo:
Through most of their annual migration, gray whales, Eschrichtius robustus, remain within 10 km of shore, but in the Southern California Bight many individuals migrate much farther from shore. This paper summarizes aerial survey and photogrammetric efforts to determine body lengths and temporal and spatial distributions of migratory gray whales in the southern portion of the Southern California Bight. Aerial surveys were flown along 13 east–west transects between lat. 32°35′N and 33°30′N during the southbound gray whale migratory seasons of 1988–90 in the Southern California Bight. Photogrammetry was used to obtain body length estimates of animals during some of the surveys. A total of 1,878 whales in 675 groups were sighted along 25,440 km of transect distance flown and 217 body lengths were measured. Using position and heading data, three major migratory pathways or corridors in the southern portion of the bight are defined. Those migrating offshore were split almost evenly between two corridors along the west sides of Santa Catalina and San Clemente Islands. These corridors converge on the mainland coast between San Diego and the United States–Mexico border. No whales larger than 11.5 m were photographed within 30 km of the mainland coast, suggesting that smaller, and presumably younger, whales use the coastal migratory corridor through the California Bight.
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From 1947 to 1973, the U.S.S.R. conducted a huge campaign of illegal whaling worldwide. We review Soviet catches of humpback whales, Megaptera novaeangliae, in the Southern Ocean during this period, with an emphasis on the International Whaling Commission’s Antarctic Management Areas IV, V, and VI (the principal regions of illegal Soviet whaling on this species, south of Australia and western Oceania). Where possible, we summarize legal and illegal Soviet catches by year, Management Area, and factory fleet, and also include information on takes by other nations. Soviet humpback catches between 1947 and 1973 totaled 48,702 and break down as follows: 649 (Area I), 1,412 (Area II), 921 (Area III), 8,779 (Area IV), 22,569 (Area V), and 7,195 (Area VI), with 7,177 catches not currently assignable to area. In all, at least 72,542 humpback whales were killed by all operations (Soviet plus other nations) after World War II in Areas IV (27,201), V (38,146), and VI (7,195). More than one-third of these (25,474 whales, of which 25,192 came from Areas V and VI) were taken in just two seasons, 1959–60 and 1960–61. The impact of these takes, and of those from Area IV in the late 1950’s, is evident in the sometimes dramatic declines in catches at shore stations in Australia, New Zealand, and at Norfolk Island. When compared to recent estimates of abundance and initial population size, the large removals from Areas IV and V indicate that the populations in these regions remain well below pre-exploitation levels despite reported strong growth rates off eastern and western Australia. Populations in many areas of Oceania continue to be small, indicating that the catches from Area VI and eastern Area V had long-term impacts on recovery.
Resumo:
Between 1889 and 1916, the U. S. Fish Commission steamer Albatross made numerous trips to waters off southern California, particularly in and near San Diego Bay. The typical pattern for many years was to conduct cruises in waters off the Pacific Northwest or Alaska in summer months and waters off southern California in winter months. The Albatross conducted the first depth soundings and benthic profiles for southern California waters and secured the first samples of many endemic marine animals of this region. Albatross collections formed the basis for numerous definitive monographs of invertebrates and vertebrates that were published in subsequent years. The Albatross anchored in San Diego Bay in 1894, conducting the first biological investigations of the bay, and returned to sample again in many subsequent years. The ship and its crew also examined Cortez and Tanner banks for exploitation potential and conducted the first biological investigations of southern California’s tuna stocks in 1915 and 1916.
Resumo:
Basking sharks, Cetorhinus maximus, are frequently observed along the central and northwestern southern California coast during the winter and spring months. These large plankton feeding elasmobranchs, second in size only to the whale shark, Rhineodon typus, had been the subject of a small commercial fishery off California in the late 1940's and early 1950's for their liver oil, rich in vitamin A, and in later years for reduction into fish meal and oil (Roedel and Ripley, 1950). These fisheries were sporadic and did not take basking sharks in large numbers.
Resumo:
This is the report from the Southern Area Fisheries Advisory Committee meeting, which was held on the 14th January, 1981. It covers information on the review of fisheries byelaws and the proposal of having a separate coarse fish licences. It also includes the report by the area fisheries officer on fisheries activities. This comments on river conditions and fishing and an update on Hollingworth and Pilot hatchery. Finally the report adds about fish mortalities, and lists of stockings carried out for non migratory trout and coarse fish by the North West Water Authority and Angling Associations which gives the size of the fish, the source from which they came from and the receiving water. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the report from the Southern Area Fisheries Advisory Committee meeting, which was held on the 8th April, 1981. It includes the report by the area fisheries officer on fisheries activities between December 1980 to February, 1981. This comments on river conditions and fishing, and an update on Hollingworth and the pilot hatchery, salmon cages in Dalton-in-Furness, and Langcliffe hatchery. Finally the report adds about stockings of coarse fish and non migratory trout added by the Angling Associations, fish mortalities and fish disease. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the report from the Southern Area Fisheries Advisory Committee meeting, which was held on the 9th September, 1981. It covers information including the consultation paper on the review of Inland and Coastal fisheries in England and Wales, and a paper on 'A National Salmon Policy'. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the report from the Southern Area Fisheries Advisory Committee meeting, which was held on the 21st October, 1981. It includes the information on the recommendations of the Area Fisheries Advisory Committees on the Review of Inland and Coastal Fisheries in England and Wales, and the restructuring of rod and line fishing licence duties. It also covers the report by the area fisheries officer on fisheries activities between March and August 1981. This comments on river conditions and fishing, and an update on Hollingworth and the Pilot Hatchery. Finally the report adds about stockings carried out by the Angling Associations, fish disease, fish mortality and management work. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.
Resumo:
This is the report from the Central and Southern Area Fisheries Advisory Committee meeting, which was held on the 18th January, 1982. It includes information on the restructuring of rod and line fishing licence duties, proposed introduction of fishery improvement grant and fishery equipment loan, schemes in 1983. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.