摘要:

SummaryLinear and multiple regression analysis was used to develop and improve models to forecast catches of two‐sea‐winter (2SW) Atlantic salmon (Salmo salar) from 43 Icelandic rivers. Catches of 2SW salmon in a given year were forecast based upon yields of grilse (fish that remain one year at sea) the previous year and upon three sea‐temperature variables from hydrographic stations in western and northern Iceland. Highly significant relations (P<0.01) were found between grilse and 2SW salmon catches for 12 of 21 western rivers and 18 of 22 northern rivers. Nine of the 22 northern rivers had at least 60% of their variation in 2SW salmon catches explained by grilse catches the previous year. Because of collinearity between sea températures and grilse catches, little benefit was derived by adding sea temperature to the models based on grilse and 2SW salmon; in few rivers did the sea températures explain significant additional variation

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00481.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryStudy on the reproductive cycle of the gudgeon, Gobio gobio L. Part 2Monthly samplings of male gudgeons,Gobio gobioL. reared in ponds were carried out to study the spermatogenesis of this cyprinid during an entire annual cycle. Together with macroscopic parameters (GSI, condition coefficients, K and K1, nuptial tubercles) the cytologic characteristics of the testis maturation were analysed. The relationship between environmental conditions and spermatogenesis was also examined. The spermatogenetic cycle of G.gobiowas divided in two separate periods: a) from October until March, during which only the spermatogonia (SgA and SgB) were present, and b) a stage of active transformation, from April until August, when all the 5 testicular cells (SgA, SgB,Scyt, Spd, Spz) were determined. Dynamic aspects of spermatogenesis were also investigated by an estimation of the proportion of each cellular stage. Spermiation, by abdominal pressure, occurred from mid‐April to end of Jul

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00482.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummarySnakehead rhabdovirus stored in cell culture medium was found to be relatively temperature resistant with ≥ 99.9% reduction in infectivity only occurring after 6 months at 15°C, 6 weeks at 25°C and 10 days at 35°C. At 25°C, virus stability was greatest in the range pH 5–7. Infectivity was less well retained at pH9 and rapidly lost at pH3 and pH11. Stability was poor in serum‐free media with a 99.9% reduction in infectivity occurring in less than 48 hours at 25°C in de‐ionized water, tap water, balanced salt solutions and artific

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00483.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe distributions of length frequencies subdivided by age of orange roughy (Hoplostethus atlanticus: Trachichthyidae) had the modal characteristics of K‐selected populations. Oceanographic data showed that the depth strata occupied by orange roughy have boundary characteristics which could lead to the development of non‐equilibrium dissipative thermodynamic structures and which would account for the K‐selection configuration of orange roughy s

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00484.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryDuring the 1987 cruise of F.S. Meteor in the Arabian Sea, respiration rates and effects of low oxygen saturation on behaviour and respiration have been investigated in two fish species.Cubiceps whiteleggiis an inhabitant of the partly oxygen‐depleted epipelagic zone. It is more tolerant to oxygen shortage than the second species,Coryphaena hippurus.At naturally occuring temperatures, first response to low oxygen was noted at values slightly below air saturation inC. hippurusand at 20–30% oxygen saturation inC. whiteleggi.After exposure to low oxygen saturation, the reaction patterns were completely different for the two species, reflecting the particular requirements of their living space. InC. hippuruslethal oxygen saturations seemed to be reached just below 60% oxygen saturation. InC. whiteleggifirst mortality occurred at 10% oxygen saturat

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00485.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryData on the distribution in 1986 of the parasitic nematode in the swimbladder of the European eel (Anguilla anguillaL.) in Flanders (Belgium) are reported. In stations where imported eels have been used for restocking, samplings generally show high infection rates thus enhancing the spread ofAnguillicola crassusin Flanders.

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00486.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe viability ofAnguillicola crassuslarvae was studied under various environmental conditions. High températures and nigh salt concentrations considerably shorten the lifetime of the larvae. This is possibly one of the reasons why infection does not occur as massively in marine biotopes as it usually does in fresh water

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1989.tb00487.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY