摘要:

AbstractThe catch‐per‐unit‐effort (CPUE) and value‐of‐catch‐per‐unit‐effort (VPUE) of reef‐associated fish species from six Fijian native fishing grounds (qoliqoli) subject to different fishing intensities were determined using records of fishing activity from a voluntary logbook scheme. Line and spear fishing techniques were used for more than half the total fishing time (h person‐1d‐1) in allqoliqoli, and yet the favoured technique in a givenqoliqoliwas frequently less efficient (lower CPUE) than other techniques. The popularity of relatively ineffective fishing methods implies that fishermen did not always attempt to maximize their catch rates. To compare fishing effort in differentqoliqoli, all effort was rescaled on the basis of its recorded efficiency (measured as multispecies CPUE) and expressed as hours equivalent to boat‐based spear fishing over coral by day to catch fish for sale. Total fishing intensity in the sixqoliqoliranged from 72 to 4310 h km‐2reef year‐1. The relationship between catch and effort was linear at all fishing intensities, suggesting that theqoliqoliwere all fished on a sustainable basis. Furthermore, whilst there was a significant difference in CPUE and VPUE between the one or twoqoliqoliwith lowest fishing intensity and all the others, there were no significant differences between these otherqoliqoliin terms of the VPUE of the saleable multispecies boat catch or the CPUE of species from piscivorous and carnivorous genera (Epinephelus, LethrinusandPlectropomus) which th

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00102.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe length distribution of adult sea trout,Salmo truttaL., from a commercial seine net fishery using a nominal minimum mesh size of 50 mm or 102 mm is described. The smaller mesh size captured sea trout larger than 210 mm whilst the larger mesh size caught sea trout mainly above 400 mm, with no fish below 320 mm. A sea trout length/ girth relationship is described, and coupled with biological data allowed the calculation of mesh sizes for the appropriate escapement of different sea ages of sea trout.

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00103.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe abundance of 0+ pikeperch,Stizostedion lucioperca(L.), in trawls was compared with water temperature, water level and commercial catches 6–9 years later. The abundance of juveniles in autumn was positively correlated with the water temperature but not with water level in May or in June. The sum of a year abundance of juveniles showed a strong correlation with the catch years later. This abundance and the cumulative water temperature between August and October inclusive in five consecutive years one year prior to recruitment into the commercial fishery explained 86% of the variation in catches. This empirical model indicates that catches of pikeperch depend on both juvenile abundance and water temperatur

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00104.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractLake‐to‐lake variation in brown trout,Salmo truttam.lacustrisL., yield from stocking was examined in 34 lakes in northern Finland. The trout were mainly stocked as 2–3‐year‐old fish. Catch statistics were compiled with information on water quality, water level fluctuations, fishing effort and lake geomorphology. Absolute brown trout yields (kgha‐1) increased with increasing stocking rate, but there was an indication of non‐linearity at higher stocking densities. Relative yields (kg per thousand trout released) were highest at low stocking rates. Stepwise multiple regression analysis was used to determine the best predictive model for lake‐to‐lake variability in brown trout yields. Seventeen measured regressands were used initially, and then replaced with scores obtained in a principal component analysis of highly correlated water quality variables and species‐specific fish yields. Three major determinants of brown trout yields in these lakes were found in both analyses: fish community, stocking rate and fishing effort. Brown trout yields from stocking were higher in lakes with proportionally high yields of vendace or vendace and whitefish and proportionally

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00105.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractRate of recapture (gill netting), habitat use, and diet of three strains of stocked brown trout,Salmo truttaL., were compared with resident brown trout in a Norwegian lake. The strains originated from an alpine lake, from a boreal lake, and from the native brown trout population in the lake. Overall recapture rate was 5–8% for all strains. The low recapture rate could be due to the relatively small size at stocking; mean fish length varied between 13.1 and 14.5 cm with strain and stocking method. Two years after release, the frequency of the different strains decreased from about 12% in the first year to stabilize at about 1%. The alpine strain showed the highest overall recapture rate, whereas the native strain was recaptured at an intermediate rate. The overall recapture rate of scatter‐planted brown trout was higher than that of spot‐planted brown trout. Immediately after being stocked, introduced fish ate less and had a less‐varied diet than resident trout; however, stocked fish adopted a natural diet within the first summer. The distribution of trout between the pelagic and the upper epibenthic habitat was similar for both the resident and the stocked brown trout. Results indicate that the habitat use of stocked brown trout is adaptive and becomes similar to that of indigeno

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00106.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractUsing catch data, changes in salmon,Salmo salarL., sea‐age and seasonal return time were compared between several Scottish east coast rivers over the last 150–200 years. Parallel long‐term trends were found, suggesting common influences affecting salmon at sea. Long‐term associations with marine environmental factors were investigated by literature review and comparisons with an index of Icelandic sea‐ice abundance. Apparent associations were shown to exist since about 1900, although the cause was not demonstrated. However, over a longer timescale, the same associations were not apparent. Unique gradual marine changes since 1900 may have resulted in perceptible associations with salmon data which may otherwise be imperceptible when short‐term marine environmental variability is greater than long‐term variability. Marine factors must affect salmon, but the complexity of the marine environment and controls on age at maturity and time of return mean that a retrospective analysis cannot be expected to identify the c

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00107.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0969-997X    

DOI:10.1111/j.1365-2400.1995.tb00108.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY