摘要:

All the summer steelheads Salmo gairdneri from the Siletz, an Oregon coastal river in which Ceratomyxa shasta does not occur, died when they were exposed to waters containing the infectious stage of C. shasta. In contrast, three strains of summer steelhead from tributaries of the Columbia River where C. shasta is endemic were resistant to ceratomyxosis. These results, together with previous work on other species, indicate that salmonids from populations living in waters free of the infective stage of C. shasta should not be stocked in waters containing the pathogen. The resistance to this disease among strains of summer steelhead from the Columbia River is believed to be a result of natural selection.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<541:RSOFSO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Etomidate was tested as an anesthetic on channel catfish Ictalurus punctatus, golden shiners Notemigonus crysoleucas, and bluegills Lepomis macrochirus. The 24-hour median lethal concentration (LC50) at various temperatures was lowest for bluegills (0.61–0.68 mg/liter) and highest for golden shiners (1.87–2.73 mg/liter). Generally, etomidate was more toxic, and induction of anesthesia and recovery from anesthesia were slower, at 17 C than at 22 and 27 C. Water hardness and pH had no or only slight effect on the toxicity and efficacy of etomidate. All channel catfish in 8 mg/liter and all golden shiners in 10 mg/liter were anesthetized within 2 minutes at 22 ± 1 C (±range) and all survived if removed from the etomidate immediately after opercular movement stopped. Both channel catfish and golden shiners were anesthetized within 15 minutes by 3 mg/liter, and all of the fish survived at this concentration for 30 minutes. Concentrations of 0.2 and 0.4 mg/liter sedated channel catfish, and 0.4 and 0.6 mg/liter sedated golden shiners. The safety index LC50/EC50 (median effective concentration) for anesthesia of channel catfish and golden shiners at 22 ± 1 C decreased from 6.2 to 5.0 and 7.6 to 4.0, respectively, as exposure length increased from 10 to 80 minutes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<544:EAAAFF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

To assess the role that temperature may play in determining the life cycle of Mysis relicta, we cultured newly hatched juveniles at 4 C and 8 C in the presence of a surfeit of food. Mysids first reached sexual maturity after 8 months at 8 C after molting 12–13 times. Mysids cultured at 4 C molted four to five fewer times in the same 8 months, yet grew the same amount per molt as the mysids cultured at 8 C. We predict that mysids that live in water of at least 8 C during the summer of their first year will complete their life cycle in 1 year, whereas mysids growing in water colder than 4 C during their first summer will require 2 years to complete their life cycle.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<551:LCOTFM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Threadfin shad Dorosoma petenense were tested to determine if they would eat benthic organisms in both the presence and absence of zooplankton. They deliberately fed on chironomids in a sand substrate when no other food was available, but when offered a choice, selected Daphnia pulex over the chironomids. When the daphnids were all consumed, the fish resumed benthic foraging. Thus, threadfin shad can shift their diet to take advantage of other available foods when their primary food is lacking.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<554:DSTBFB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Ponds at Auburn University, Alabama, stocked with 10,600 channel catfish Ictalurus punctatus per hectare that were fed at rates up to 66 kg feed/hectare per day, received water exchanges totaling 0, 1, 2, or 4 pond volumes between July and September. Although feeding rate was high enough to impair water quality, concentrations of dissolved oxygen, total ammonia nitrogen, nitrite-nitrogen, and chemical oxygen demand did not differ (P > 0.05) among treatments, and fish production was not increased by water exchange (P > 0.05).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<557:EOTIOW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Methotrexate, kenalog, and cyclophosphamide were tested for immunosuppressive activity in steelheads Salmo gairdneri. Three 60-mg/kg injections of methotrexate prevented an increase in serum antibody titer in fish previously immunized with killed whole cells of Aeromonas salmonicida. No immunosuppression in previously immunized steelheads was observed following injections of kenalog and cyclophosphamide.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<561:EOMKAC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Tubercular lesions were found in striped bass Moroue saxatilis from four areas in northern California and Coos Bay, Oregon. The prevalence of infected striped bass ranged from 25% to 68% in California and was 46% in Oregon. This is the first report of tubercles caused by an acid-fast bacillus in wild populations of west coast striped bass.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<565:TLIPCP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Eleven of 42 adult striped bass collected from Coos Bay, Oregon, were possibly protandrous. The older hermaphrodites, ages 7 to 10 years, showed increasing signs of pathology associated with egg retention.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1983)112<567:PHISBF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1983.10493226

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor