摘要:

ABSTRACTThe survival rates of salmon stocked as eyed ova and green eggs in an upland trout stream were compared by electrofishing a number of sites during their first summer and at the end of their first complete year. The results were compared with the survival rates in the naturally spawning trout population. It was found that the survival rates from eyed ova were considerably better than that from green eggs and the results were discussed in the context of environmental effects and territorial competition in emerging fry.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1981.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTRoach spawned on two sites whereFontinalis antipyretica(Hedw.) grew thickly on vertical pilings. The eggs were distributed throughout the fronds ofFontinalisbut were concentrated near the water surface. The fish spawned on those parts of the sites where the current adjacent to the weed was relatively fast. The sudden drop in water levels caused by weed cutting presents a potential threat to spawning success.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1981.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe efficiency of electric fishing for salmonids was found to decrease with increasing river width. The results demonstrated that mean efficiencies in excess of 50% could be obtained using two anodes up to a river width of about 6.5 m and using three anodes up to a river width of about 11 m. Yearling and older fish were captured more efficiently than fry at equivalent river widths and this was discussed in relation to differences in their behaviour.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1981.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe composition and abundance of Northern pike (Esox luciusL.) populations in four shallow waters was monitored during a 4–5 year period, using mark‐recapture methods. In general, the populations were sampled by using a combination of fishing gear but pike that completed their first growing season (0+ pike) are captured quantitatively by electrofishing (3 kw, DC) exclusively.Within the length range of 0–54 cm fork length, the biomasses of 0+ pike appeared to be negatively correlated with those of larger pike. It is suggested that intraspecific predation is mainly responsible for these relations. The standing stock of<54‐cm pike was found to be determined by the amount of aquatic vegetation and more especially so if the different habitat preference of 0+ pike, 0+

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1981.tb00011.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1981.tb00012.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Book reviewed in this articleForeign Investment in the U.S. Fishing Industry. By J. SULLIVAN and P. O. HEGGELUNDThe Management of Forest Streams. By D. H. MILLS.A River for All Seasons. By TOM WILLIAMS.World Fish Farming: Cultivation and Eeonomics. by E. EVAN BROWN.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1981.tb00013.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY