摘要:

Research results concerning nutrition of the freshwater prawnMacrobrachium rosenbergiiand applicability to the production of feed for intensive culture are presented. Future research approaches are recommended and comparisons to the nutrition of penaeid shrimp species are provided.

ISSN:1064-1262    

DOI:10.1080/10641269409388551

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Winterkill is a common phenomenon in many eutrophic lakes subject to prolonged ice and snow cover. These conditions can lead to greatly reduced oxygen absorption and generation under ice‐cover, compared with oxygen consumption, and to dissolved oxygen (DO) depletions below concentrations required for fish survival. DO requirements of fishes under ice‐cover are not well defined, but are much reduced compared with summer conditions, with many fishes surviving at DO concentrations <1.0 mg/1 at water temperatures of 0 to 4°C. A lower DO limit of 2 mg/1 for gamefish has been suggested. Typically, as under‐ice DO concentrations become progressively depleted, the more valued gamefish succumb first, leaving less desirable fishes; and, in extreme cases, no fish survive. Frequencies, causes, and preventions of winterkill have been most thoroughly studied in Michigan, Minnesota, Wisconsin, and the Great Plains region of the U.S. and Canada. Long‐term records from these areas indicate that winterkill frequency is related to duration and intensity of winter weather conditions; but some lakes experience winterkill almost every year regardless of the weather.

ISSN:1064-1262    

DOI:10.1080/10641269409388552

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Three types of tags, external, internal, and sonic, have been used to study migration of the American lobsterHomarus americanus. Tag loss and interpretation of returned tag data are serious problems associated with internal and external tags. Lobster tracking using sonic tags is still in the pilot stage. Lobster migration is redefined to include horizontal and vertical displacements. Depth of displacement is a more reasonable measurement of lobster migration than horizontal distance traveled. Two distinct lobster populations are discernable based on their ecological habitation and migratory behavior. Evidence in this review suggests that the deep‐sea lobster migrates, whereas the coastal lobster may move within a limited range.

ISSN:1064-1262    

DOI:10.1080/10641269409388553

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor