摘要:

Many exotic organisms, particularly fishes and plants, have become a part of Florida's aquatic ecosystems. The majority of these organisms was introduced accidentally as a result of activities of professional aquarists, particularly through carelessness by tropical aquarium fish farm operations. One exotic fish species was established from the release of stocks imported for experimental purposes. Amateur aquarists and tourist attractions also have the potential for introducing exotic aquatic organisms. Future introductions can be reduced through better safeguards in respect to prevention of escape and more public education.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<1:EAOIFW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

This paper presents a synopsis of investigations concerned with culture of striped bass (Morone saxatilis, Walbaum) fingerlings. An historical review of significant events includes the development of hatcheries and rearing techniques. Changes in food habits and feeding behavior occur with early development of the fish. Early instars of copepods and cladocerans are preferred natural foods until the fish are about 10 mm in total length. The diet of fish in the 10–30 mm size group consists mainly of adult copepods supplemented with some cladocerans and insect larvae. Fish in the 30–80 mm size group utilize fewer copepods while cladocerans and insect larvae make up the major portion of the diet. Insect larvae are the most important foods of fish in the 80–100 mm size group.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<13:AEOSBF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Striped bass Morone saxatilis from the Upper Chesapeake Bay were studied to determine if discrete populations exist. Spawning fish and juveniles in five rivers, the Patuxent, Potomac, Choptank, Elk, and Nanticoke were sampled. Discontinuous polyacrylamide gel electrophoresis separated the serum proteins for population analysis. Five proteins, which were not related to the age, sex, or time of collection of striped bass, were used to discern populations. The Elk River striped bass are very distinct. Both the Choptank and Nanticoke are also distinct but show some connection with the Patuxent and Potomac striped bass. The Patuxent and the Potomac striped bass could not be distinguished from each other on the basis of the five proteins studied. The geologic evidence supports the theory of population formation for striped bass in the Chesapeake Bay. Management implications of the striped bass populations are also discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<21:EDOPOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The gut contents of rainbow trout (Salmo gairdneri), kokanee (Oncorhynchus nerka), and two salamanders (Ambystoma gracile and Taricha granulosa) from Marion Lake were compared. The species found in these four predators were very similar but each predator concentrated on different prey. The kokanee concentrated on species present at the surface or in the water column, and the trout on larger benthos. The salamanders also fed on benthos but usually chose smaller size classes. In comparing the effect of the four predators, the average volume of food present by weight in the gut was multiplied by a proportional converter for the rate of passage through the gut, the mean meal size, and by the number of individuals in the population. The results suggested that Salmo gairdneri ate over half by weight (56%) of all the food taken by the four predators combined; kokanee and Ambystoma gracile were less important and consumed 25% and 19% respectively; and Taricha granulosa because of its low number and slow growth was unimportant (1%).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<33:ACOTFO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

In Halawakee Creek, Percina nigrofasciata showed two distinct feeding peaks; one in the morning and a higher one in late afternoon. Immature forms of Diptera, Ephemeroptera, and Trichoptera were dominant in the diet over the 24-hour period. Although these organisms were most abundant in drift during the night, most were eaten during daylight. Daytime feeding peaks suggests that P. nigrofasciata are visual feeders. Daily ration varied from 2.6 to 4.9% of the body weight.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<48:FHAFCO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The paper brings together major inferences from: (1) classical limnology—lake and stream typology, the role of major abiotic variables; (2) fisheries limnology—Ryder's morphoedaphic index, Jenkins' reservoir findings, concepts of habitat niches; (3) studies of ecological structure of communities—succession, diversity, stability, variability, regulation; (4) recent developments concerning the effects of major cultural stresses on fish communities. A model is proposed to interrelate these and other concepts, and then relate them all to conventional fisheries practices and objectives. The model is directed at events and processes at the community level of organization and it is argued that much of fisheries theory and management practices of the future will perforce need to be directed at the community level.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<56:TABEMO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A pond located on the Texas A + M University range area, College Station, (1.78 surface ha, 40,427 m3) was treated with anhydrous ammonia in November 1968, for evaluation of this technique for simultaneous fish eradication, pond fertilization, and aquatic vegetation control. This paper reports the effect of such treatment on pond ecology.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<73:EOAAOA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Winter flounder with white spots on the eyed side were unusually common among fish of the 1959 year-class caught on north-central Georges Bank in 1964, 1965, and 1966. The water on eastern Georges Bank was considerably colder than normal in the spring of 1959 when young flounder were developing. A possible relationship between lowered development temperature and white-spotting is suggested.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<83:WSITYO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Several bioassay methods, responses, and end points were evaluated for use in determining the temperature requirements of northern pike embryos. Large differences in maximum embryo survival to hatch occurred among experiments that could not be attributed to effects of water temperature alone. Emphasis was placed on evaluating the relative effects of temperature on embryo survival by our correcting for differences in fertilization success among experiments. The most variable end point among experiments was the optimum temperature, while the most reproducible end point was the median tolerance limit (TL50). The lower and upper TL50s were 6.9 and 19.2 C for normal hatch and 6.3 and 19.9C for total hatch. The age of the embryo at the time of exposure had a great effect on these tolerance limits. Temperature shock, source of fish, and wet fertilization in hard and soft water had negligible effects on these tolerance limits. Recommendations were made for routine thermal bioassays for fish eggs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<89:TRFEAL>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Reproductive aspects of the horse mackerel in Chilean waters were determined from 309 specimens collected between January 1963 and April 1964 in three fishing locations. Changes in the gonadosomic indices, condition factors, and distribution curves of egg sizes indicated that horse mackerel spawned in December in Antofagasta and in February in Coquimbo and Valparaiso. Spawning lasts probably less than a month. Female horse mackerel may spawn for the first time in their third year of life (about 36 cm fork length and 600 grams body weight). Four-year-old females were, in general, adults. Large variation in the fecundities of fish of similar size and weight, respectively, was found. Five-year-old females contained an average of 639,105 yolked eggs. The average number of yolked eggs per gram of fish was greater in Coquimbo (590) than in Antofagasta (383) and Valparaiso (332).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<101:GMAFOH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor