摘要:

The long-term effects of three levels of dissolved oxygen (100, 60 and 36% of air saturation) on channel catfish, Ictalurus punctatus, were evaluated under two feeding regimes—a constant rate of 3% of biomass daily and ad libitum. At ad libitum rates (6-week duration) average gains of 159, 124, and 65 g per fish were obtained in tanks containing oxygen at 100, 60 and 36% of saturation, respectively. In both experiments food consumption and efficiency were drastically reduced at 36% oxygen saturation. Survival rates were 100% in all groups, thus suggesting that disease and parasite problems were not enhanced by a hypoxic environment. In these studies catfish did not demonstrate a polycythemic response to hypoxic conditions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<835:TIODOO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Sublethal, incipient upper lethal, and total lethal temperatures were obtained for the duskystripe shiner, Notropis pilsbryi, and the bluegill, Lepomis macrochirus. Both species were exposed to a gradual temperature increase of 2 C per day and to sudden temperature increases after being acclimated to a temperature of 21.5 C. Results indicate that the incipient upper lethal temperature of the bluegill, with a 2 C rise in temperature per day, is 35.5 C and that of the duskystripe shiner is approximately 32.0 C. Resistance times of both species to a sudden temperature increase were also determined.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<838:NOTULT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A field technique is described for examining schools of fish by recording their times of capture during electrofishing. The technique is suitable for streams and rivers where the fish can be seen as they are caught. Analysis of the time intervals between minnow captures was carried out by fitting a mixture of gamma and exponential distributions. The results show that clusters of minnows were encountered at random during fishing. The clusters are considered equivalent to the schools in which minnows live in the wild, but the inadequacies of verbal recording preclude any biologically meaningful analysis of the within-cluster distributions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<840:SFMOMS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Silk snappers collected at mean depths of 81 to 378 m had fork lengths ranging from 18 to 67 cm. There was no significant variation in relative diurnal abundance and no significant variation in depth distribution over the mean range of 157 to 234 m. Variation in relative monthly abundance was slight. One distinct mode in the length frequency distribution was present between 30 to 49 cm. An approximate length-weight relationship was calculated.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<843:CTTBOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Three sets of twins hatched from 900 eggs of Porichthys notatus Girard. Two sets were immediately preserved. At no time during development did the third set differ significantly from nontwin larvae. Twinning probably occurred during cleavage.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<846:TIPNG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Immersion of swimmerets or nonplumose setae in hematoxylin is a successful field method for detection of residual egg cement on brushed lobsters.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<847:ATFDOB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<848:JYMFTB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1973.10492856

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1973.10492863

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor