摘要:

A nonlethal morphometric method to assess smolt status of juvenile steelheadOncorhynchus mykisswas validated. Fish were collected from hatcheries before release and during their seaward migration in a large river system. Fifteen anatomical landmarks were digitized from photographs of each fish, resulting in 34 morphometric characters based on a truss network. Principal component and canonical discriminant function analyses were used to assess smolt status. A single canonical variate was significantly correlated with gill Na+,K+-ATPase activity, a commonly used measure of smolt status. This nonlethal method may be a useful measure of smolt status when sacrificing fish is not desirable or possible; it requires little training to perform, but it does require a larger sample size than some other methods.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1995)124<0764:ANMOSS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Mitochondrial DNA analysis of 16 walleyesStizostedion vitreumoriginating from Luxapalila Creek in northeastern Mississippi showed that they were genetically distinct (2.34% sequence variation) from walleyes collected from the Mississippi River basin and other northern drainages. There was no genetic variation among the 16 fish analyzed. This work confirms the existence of a unique genetic form of walleye in the Tombigbee River drainage, but further research is required to determine whether this distinct form occurs throughout the Gulf Coast drainages of Mississippi and Alabama. Because the genetic integrity of this southern walleye strain is threatened by stocking of northern walleye strains and by invasion of northern strains via the Tennessee–Tombigbee Waterway, a careful monitoring program with genetic markers should be implemented.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1995)124<0770:NMDACT>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The estimation of age of lake sturgeonAcipenser fulvescensby counting annuli in transverse sections of pectoral fin rays is validated through two methods: capture–recapture and examination of annuli laid down after injection of an oxytetracycline (OTC) marker. At first capture of each individual, the first ray of the right pectoral fin was removed. At recapture, 1–3 years later, the first ray of the left pectoral fin was removed. Differences between counts of annuli in rays collected at capture and at recapture were the same as the number of years that individual had been at large. At first capture lake sturgeons ranged in age and size from 4 years old and 43 cm fork length (FL) to 34 years and 115 cm FL. At recapture, they ranged from 6 years and 45 cm FL to 36 years and 122 cm FL. Fin ray sections of recaptured individuals previously injected with an OTC marker showed a discrete fluorescent band under ultraviolet light. The number of annuli outside this band corresponded to the number of years between OTC injection and recapture. This is the first validation of aging techniques in lake sturgeon. However, the close proximity of some annular rings can result in underestimation of true age if two rings are counted as one; thus, we urge care and caution when determining ages of lake sturgeon through enumeration of annuli in fin ray sections.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1995)124<0777:VOAEFT>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Juvenile coho salmonOncorhynchus kisutchand sockeye salmonO. nerkawere marked by jet injection to determine mark retention of three substances: Alcian Blue dye, black india ink, and acrylic paint (red, fluorescent yellow, and fluorescent orange). Fish were marked on the caudal fin and then held for 40 weeks in flow-through freshwater tanks. Coho and sockeye salmon both retained Alcian Blue and fluorescent orange marks best. The highest mark retention after 40 weeks was 73% for Alcian Blue marks on sockeye salmon. Overall mark retention was greater for orange-, yellow-, and black-marked coho salmon than for similarly marked sockeye salmon. Differences in growth rate—sockeye salmon grew about 7 mm more than coho salmon—probably contributed to the differences in mark retention between species. All colors appear suitable for short-term (<6 weeks) marks. For long-term (>6 weeks) marks, we recommend Alcian Blue dye or fluorescent orange or yellow acrylic paint for coho salmon and Alcian Blue dye for sockeye salmon.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1995)124<0782:ROJIMO>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659-124.5.786

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor