摘要:

In Ichkeul Lagoon there are 24 fish species belonging to 15 families. These fish were obtained from the commercial fishing fleet and from scientific collections made during experimental, fishery independent sampling. Most species are of marine origins and enter the Lagoon to feed. Among residential forms, there are two species of freshwater fishes(Barbus callensisandAphanius fasciatus).However, future plans to modify the water flow constitute problems for the Parc National de líIchkeul. Disturbance in the hydrological regime will inevitably have some repercussions on the fish biology and their population dynamics. The closing of the lock, installed on the Oued Tinja, may compromise the entering of migratory fish which will result in a total halt to fishing activity.

ISSN:1125-0003    

DOI:10.1080/11250009809386837

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A set of 410 river sections were studied to assess Corsican freshwater fish communities affinities with insular characteristics. Coastal rivers in the French Mediterranean region served as a mainland reference. On a large geographic scale Corsican communities show a species impoverishment of about 52% with the lack of all primary freshwater species such as cyprinids in the native community. The number of species in the watershed surface waters is not significantly different from the mainland, however, the low intercept of the relationship species/area relationship is indicative of differences observed between mainland and Corsica. On a local scale, the upstream Corsican community appears similar to the mainland community. But, as distance from the source grows, the presence of euryhaline species become more important in Corsica. These species, coming from the sea compensate the rarity of primary freshwater species. On the aspect of habitat extension, because of the absence of competitors on the island, troutSalmo truttahas clearly enlarged its downstream habitatniche.

ISSN:1125-0003    

DOI:10.1080/11250009809386838

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In the Inner Delta of the River Niger fish lateral migration from the river toward the plain was monitored at the beginning of the flood during 1991 and 1994, two hydrologically different years. Fish sampling was performed with a fyke‐net (mesh‐bar 8 mm) set in a small channel linking river to plain. This first step of the migration is generally less studied but yet very important for optimal colonization and natural fish farming of the food resources on the floodplain. The adults and/or the juveniles of more than thirty fish species representing thirteen families migrate yearly at the beginning of the flood from the river toward the plain. The species diversity (Shannon index) was similar for the two years (2.72 in 1991 and 2.44 in 1994). On the whole the migration into the plain was more important (+24% in number) in 1994, a high flood year. The relationships between the different migrating fish species and the water discharge, temperature and conductivity are evaluated. The between year variation of migratory behaviour was investigated. These results on the migratory behaviour could be used in the conservation and improvement of fisheries and in the development of fish farming in this area of Mali.

ISSN:1125-0003    

DOI:10.1080/11250009809386839

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A survey of the fish fauna of the Chindwin headwaters in Manipur, India (comprising of the rivers, viz., Manipur, Chingai, Chatrickong, Maklang, Lokchao and their tributaries) has been undertaken. A total of 117 species belonging to 65 genera and 25 families has been recorded. The fauna is a mixture of endemic hill stream, Burmese, Indochinese and widely distributed forms. Except a few species, most are medium to fast running torrential forms. The evolution of the diverse groups and endemic species in relation to geological history is discussed.

ISSN:1125-0003    

DOI:10.1080/11250009809386840

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The diversity of fish species in an transition zone between the River Paranapanema and the head mouth of the Jurumirim Reservoir was evaluated. Fish samples were collected from October 1995 to September 1996, by experimental fishing (gill‐nets and sieve), in three marginal shallow lagoons and two channel river zones. Gill‐net collections resulted in 21 taxons of native fishes. Detritivorous Characiformes such asSteindachnerina insculptawere predominant. Sieve collections resulted in 31 taxa and the Tetragonopterinae subfamily was the/most representative group, which included small species asCheirodon stenodon.The equi‐tability index characterized the high heterogeneity of fish numeric abundance, reflecting the dominance of a few groups. A significant relationship between biotic and abiotic variables was indicated by the first canonical function. In comparison with other regions of the drainage basin, the ecotone zone studied indicated a higher species richness and, in the case of some species, fishes in all stages of development. This study demonstrated the necessity to preserve the ecological zone for the fishing and fishery management in the reservoir.

ISSN:1125-0003    

DOI:10.1080/11250009809386841

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Carp, common bream, white bream, wild goldfish and roach are the most common large‐sized cyprinids in the littoral zone of Lake Balaton. Their cumulative average contribution to the littoral fish fauna is between 65.0% and 86.2% by weight but the relative abundance of each species differs by habitat. The diet of four of these five cyprinids significantly differed within and between all the three habitats examined The highest food‐niche overlap was detected between carp and white bream along the stony shoreline and in the reed grass stands (Horn's Index). However, high food‐niche overlaps were common in the open water areas, where all these species compete for similar food types. According to our results, the interspecific competition among cyprinids is expected to increase with the implementation of shoreline regulations and the destruction of the reed‐grass habitat.

ISSN:1125-0003    

DOI:10.1080/11250009809386842

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The braided hydrosystem of the Szigetköz floodplain played a prominent part in the structure of the fish communities in the upper section of the middle river Danube Regulations and flood control measures have modified the natural resources of the area since the 19thcentury. At the end of 1992, the River Danube was diverted to the by‐pass canal of the Gabcikovo Hydroelectric Power Plant and most of the small tributaries to the river became dry in the floodplain. The juvenile fish assemblages have been monitored since the completion of the Dam of the River Gabcikovo. The monitoring results of parapotamic and plesiopotamic backwaters demonstrate the importance of hydrological connectivity of the floodplain tributaries.

ISSN:1125-0003    

DOI:10.1080/11250009809386843

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A total of 44 species belonging to 20 families, representing a broad diversity of marine fishes, were identified and examined from Tunisian inshore fisheries sampling efforts. A parasitological study of these fish species revealed a great diversity of their parasitic copepoda. About 53% of examined species were infected by at least one species of parasitic copepod. We report 38 parasite species belonging to seven families of which 17 are new record for Tunisia. Moreover, the diversity of the copepods parasite varied with host characteristics. The specificity of the copepods varied widely as well.

ISSN:1125-0003    

DOI:10.1080/11250009809386844

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The challenges of conserving freshwater fish species are daunting. Aquatic ecosystems are poorly understood, relatively unmanageable, shared by multiple users and highly vulnerable to human interventions. The ‘cocktail of threats’ to freshwater fish includes, dams, pollution, interbasin transfers, alien introductions, all mainly due to a burgeoning global human population. Worldwide, freshwater fish species (which make up 25% of the world's vertebrates whilst occurring in only 0.01% of the Blue Planet's water) are being threatened. High extinction rates are forecast and yet even in educated circles there is a “So what?”; attitude to this crisis. In this paper we discuss what is happening to the freshwater fish faunas of the globe and why, but more importantly what should be done and how. There are several options including a cyberspace route. For surely it is time for the global village to focus on fresh water‐the reason our planet is habitable.

ISSN:1125-0003    

DOI:10.1080/11250009809386845

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The fishes of the Laurentian Great Lakes have been studied and managed with various philosophies involving single species, groups of species, and ecosystems. Only recently has the emphasis shifted to a concern for biodiversity. Biodiversity has been strongly effected by habitat change, loss of indigenous species, introductions, contaminants, and changes in societal attitudes to ‘conservation’ and resource partitioning. At present there are approximately 153 established species in the lakes (not the basin). Of that total, 124 are indigenous, and 30 are naturalized. The number of species now known to have been introduced into the lakes is 57. Introductions result from authorized and unauthorized vectors. Introductions serve to indicate only one of the many impacts. In 1955 the binational Great Lakes Fishery Commission established a three‐year study entitled ‘The Role of Biodiversity in the Management of the Fishes of the Great Lakes’. The objectives of the study were the elucidation, for fishes, of the historical changes in diversity and zoogeography, food webs and ecological relationships, and human attitudes in regard to sustainability and utilization. The ultimate goal of the study was a set of recommendations to the resource managers that incorporate a concern for the maintenance of biodiversity in the goal of sustainable, consumptive and non‐consumptive, use of the resource.

ISSN:1125-0003    

DOI:10.1080/11250009809386846

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor