摘要:

Abstract The movement of sea trout.Salmo truttaL., smolts through the estuary of the River Avon, southern England was studied using miniature 300 kHz acoustic transmitters and an array of strategically placed acoustic sonar buoys. Sea trout smolts were trapped 3.25 km above the head of tide as they moved downstream and the transmitters were surgically implanted into the peritoneal cavity of the fish. Subsequent movement of the smolts through the estuary was predominantly nocturnal and occurred mainly during an ebb tide or the period of slack water between two high waters. During the hours of darkness the ground speed of the smolts through the estuary was similar to that of passively drifting objects. However, where movement did occur during daylight hours ground speeds of smolts were significantly slower. Vertical salinity profile measurements of the estuary indicated that individual smolts may have experienced salinities ranging from fresh to 100% sea water during their migration. The behaviour of the smolts is discussed in relation to the possible environmental and physiological cues controlling the estuarine migratio

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract Stocking, transfer and introduction of fish are commonly used to mitigate loss of stocks, enhance recreational or commercial catches, restore fisheries or to create new fisheries. However, many stocking programmes are carried out without definition of objectives or evaluation of the potential or actual success of the exercise. This paper describes a strategic approach to stocking aimed at maximizing the potential benefits. A protocol is discussed which reviews factors such as source of fish, stocking density, age and size of fish at stocking, timing of stocking and mechanism of stocking. The potential genetic, ecological and environmental impacts of stocking are describe

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract The development of distant water fisheries at West Greenland and in the Northern Norwegian Sea during the 1960s and, more recently, in the Faroese zone, led to the establishment, in 1984, of the North Atlantic Salmon Conservation Organization (NASCO). This paper summarizes the progress made in the 10 years since this Organization was established towards achieving its goals of conservation, restoration, enhancement and rational management of salmon,Salmo salarL., stocks. Agreements on regulatory measures have reduced the proportion of the total catch taken by the distant water fisheries and, in the case of the West Greenland fishery, management is now firmly based on scientific advice. The stability created by these regulations has allowed NASCO to address the broader areas of conservation called for under the Convention and international action has been taken to address a number of threats to the resource, including the impacts of aquaculture, introductions and transfers, and fishing in international waters by non‐contracting parties. These actions are described and the paper concludes that NASCO has a significant role to play in the future, both through continued regulation of the fisheries and by promoting international cooperation to address these broader threats to the resou

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract Logistic curves of the average growth in length were elaborated for young‐of‐the‐year perch,Perca fluviatilisL., zander.Stizostedion lucioperca(L.), ruffe,Gymnocephalus cernua(L.), bream,Abramis brama(L.), and roach,Rutilus rutilus(L.), using data from 62 localities. Mean relative deviation from this average growth (MRDAG) is proposed as a simple and reliable indicator of growth rate. The MRDAG for perch, zander, bream and roach showed a significant negative linear relationship with the geographical l

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract In an experimental stream containing available refuge zones, moderate and instantaneous flow variations did not cause high mortality or substantial increase in downstream migration of 2‐month‐old grayling,Thymallus thymallusL. Fish were able to react rapidly to spate simulations by a change in space utilization determined by changes in water velocity patterns. Reaction of fish to these experimental flow variations corresponded to a refuge strategy, i.e. seeking shelter and minimizing the distance to fi

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract In total, 8211 1‐year‐old and 14839 2‐year‐old hatchery‐reared brown trout,Salmo truttaL., from 11 stocks were released at the mouth of the River Imsa, southwestern Norway. The recapture rates and total estimated yield were higher for 2‐ than 1‐year‐old trout, although recapture rates varied between years of release and stocks. The recapture rate increased with mean individual weight at time of release. Total estimated yield from the individual groups of 1+ trout ranged from 2 to 20 kg per 1000 trout released and for 2+ trout between 11 and 250 kg per 1000 fish released. In all cases, yields were lower than the economic break‐even yield. Most fish were recaptured the year of release (89.2% of 2+ and 76.2% of 1+ trout). Almost 31% of the recaptures were caught at sea and 69% in fresh water; 95.8% of the latter were taken in

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Book reviewed in this article:Bioeconomic Analysis of Fisheries. By R. Hannesson.Eutrophication: Research and Application to Water Supply. Edited by David W. Sutcliffe&J. Gwynfryn Jones

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1994.tb00166.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1970.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY