摘要:

The literature was reviewed to determine the number of fertile, interspecific fish hybrids produced naturally and artificially. A total of 130 interspecific, natural crosses resulted in fertile F1hybrids, and 150 artificially produced interspecific crosses produced fertile F1hybrids. The validity of species concepts with reproductive isolation in their definition is questioned. The presence of fertile hybrids in 45 intergeneric crosses makes their current classification questionable.

ISSN:1064-1262    

DOI:10.1080/10641269908951360

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Chinook salmon (Oncorhynchus tshawytscha) formerly occurred in great abundance within the California Central Valley drainage and were a correspondingly important part of the subsistence economics and cultures of the indigenous peoples of that region. Salmon and other fishery resources on the Central Valley floor were part of a resource base that enabled resident Native American groups to attain some of the highest population densities to occur among the non-agricultural native societies of North America. Indirect estimates of aboriginal harvests prior to Euro-American settlement of the region indicate that the native fishers may have exploited the Central Valley salmon resource on a level comparable to that later attained by the immigrant Euro-American fishers of the late ninteenth century commercial fishery. The salmon resource also figured, to varying degrees, in native interactions— from trade item tocausa belli. Among the last intact native groups in California reliant on a salmon-based subsistence economy were the McCloud River Wintu—a people who were instrumental in the successful operation of the U.S. Fish Commission egg-collecting station on the lower McCloud River that supplied salmon eggs for shipments to U.S. Eastern states and overseas countries.

ISSN:1064-1262    

DOI:10.1080/10641269908951361

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The culture of live microalgae to feed larvae and spat is one of the major bottlenecks in bivalve culture. Consequently, there is a strong need for alternative diets to replace live microalgae as food for bivalves in commercial and research hatcheries. This article initially reviews the literature on the nutritional requirements of bivalves and continues with a review of the development of alternative and artificial diets for bivalves. Although a limited number of such diets have been assessed experimentally, their nutritional value is currently limited by a general lack of knowledge of the nutritional requirements of bivalves. The importance of the development of artificial diets, whose nutritional composition can be precisely manipulated, in order to study bivalve nutrition is emphasized. In the absence of clearly defined artificial diets, dietary vehicles such as microcapsules and spray-dried microalgae are currently the most promising tools to study the nutritional requirements of bivalves.

ISSN:1064-1262    

DOI:10.1080/10641269908951362

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The ‘Code of Conduct for Responsible Fisheries’ adopted by the Food and Agriculture Organization (FAO) of the United Nations (UN) in 1995 (FAO, 1995) is discussed. Implementation of this Code in the tuna fisheries is highlighted because compliance with this Code is the fundamental condition for tuna fishing nations to be able to continue to fish and to sustain tuna fisheries. Four important subjects in the Code are discussed extensively: resource analyses, mitigation of bycatch, strategies for management and stock propagation. The current situation regarding adherence to the Code is reviewed. Then problems and difficulties with implementation are summarized and some potential approaches, ideas and ongoing attempts are introduced and discussed. Throughout, it is realized that mitigation of bycatch is the most serious task for responsible and sustainable tuna fisheries. Several successful attempts have been made to mitigate bycatch of some species. It is likely to be possible to solve bycatch problems for other species in the near future because of significant efforts by tuna fishing nations toward this goal. In addition, it is realized that data collection systems and tuna resources analyses are improving, management strategies are evolving, and stock propagation is promising.

ISSN:1064-1262    

DOI:10.1080/10641269908951363

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor