摘要:

Channel catfish (Ictalurus punctatus) farming is the most economically valuable aquaculture industry in the U.S., with over 200,000 t of fish processed in 1994. Over 70% of the fish were grown in earthen ponds in the Yazoo‐Mississippi River floodplain of northwest Mississippi ("the Delta"). Elements of the physical geography of northwest Mississippi that contribute to the success of channel catfish farming are described in this review. Culture methods and water‐use practices are summarized to provide a framework for a review of the biological and chemical environment of catfish ponds in the Delta. Emphasis is placed on factors of practical importance, including the dynamics of the pond phytoplankton community and the central role of phytoplankton metabolism in pond ecology. The characteristics of pond bottom soils and the nature of catfish pond effluents are also described.

ISSN:1064-1262    

DOI:10.1080/10641269609388577

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Fisheries managers often assess fish populations using catch per unit effort (CPUE), size and age structure, growth, and condition. For many freshwater fishes and common sampling gears, CPUE, size and age structure, and condition are highest in the spring and fall, while growth commonly is fastest during the summer growing season. However, there are exceptions to these general trends, especially in populations with erratic recruitment, growth, or mortality. At the least, CPUE, size and age structure, growth, and condition of fish should be expected to change with season, given the effects of variable recruitment, growth, and mortality. However, if recruitment, growth, and mortality are relatively stable, seasonal changes in sampling data occur due to changes in fish behavior caused by many factors (e.g., changes in temperature, turbidity, food availability, photoperiod, etc.). However, these patterns of change through the seasons should not necessarily be assumed to be the same for all fish species or for species in all habitats or geographic regions. Thus, managers and researchers need to consider the seasonal patterns in sampling data for a particular species within a certain habitat in their geographic region when collecting standardized data sets, and when assessing populations and communities.

ISSN:1064-1262    

DOI:10.1080/10641269609388578

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Information concerning mineral nutrition of fish and marine crustaceans is rather limited compared to that available for terrestrial animals; however, significant advances have been made in recent years. This article summarizes pertinent information about mineral nutrition of fish and marine crustaceans, including classification and general functions of the minerals; dietary essentiality and/or quantitative requirements; bioavailability and dietary interactions; and general recommendations for dietary supplementation. Dietary requirements for approximately ten minerals (calcium, copper, iodine, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc) have been identified for fish, and seven minerals (calcium, copper, phosphorus, potassium, magnesium, selenium, and zinc) have been recommended for inclusion in penaeid shrimp and lobster feeds. Based on current literature, it is clear that when evaluating the dietary essentiality of a mineral, not only growth must be evaluated, but also tissue stores, biochemical indicators (e.g., enzyme reaction rates), and effects on the general development of the animal should be assessed. Due to limited studies concerning dietary mineral requirements of marine fish and crustaceans, methodologies and requirement estimates for other species are recommended as guides for research with marine fish and crustaceans.

ISSN:1064-1262    

DOI:10.1080/10641269609388579

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor