ALBERT

Notes: SUMMARY— The velocities of falling films of water on a stainless steel plate (8 by 1.5 ft) with No. 4 surface finish were measured by the salt conductivity method for flows varying from 50 to 250 Ib/min. The downflow times between 2 fixed electrodes, 6 feet apart on the plate, were measured by a Solu-Bridge flow timer. The film velocity measurements were made with the plate vertical and inclined 30 degrees from vertical, with water at 70 and 140°F. Another setup with a smaller plate (4 by 1.5 ft) and a constant flow of 45 lb/min was used to study the characteristics of falling films of water on Teflon, glass and stainless steel surfaces. The plates could be positioned at any positive or negative angle. The effects on wave structures were recorded photographically. The results showed highest velocities when the plates were vertical. Velocities increased with flow rate and temperature. At a given slope, film velocities were higher for the flow clinging to the underside of the surface than for the flow down the upper side of the surface.

Notes: The principal focus of this study was an examination of the relationship between diallelic variation at the MEP-2* locus and growth and survival in Atlantic salmon parr. In addition, patterns of growth and survival among genotypes at the AAT-I*, IDDH-I* and ZDHP-2* loci were also examined. Significant differences in growth were found among MEP-2* genotypes, with *100/ 100 homozygotes largest in one of two independent comparisons and the *125/I25 homozygotes largest in the other. No growth differences were observed among genotypes at any other locus. Although no significant differences were found in survival among genotypes at any locus, results of joint analysis of the patterns of growth and survival among MEP-2* genotypes were consistent with a model of positive size-selective mortality. The demonstration of growth differences among MEP-2* genotypes in parr and smolts may indicate an association between selection on this locus in fresh water and previously reported differences in sea-age at maturity among MEP-2* genotypes in Atlantic salmon.

Notes: Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, 〉350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in 〉200 river systems across the species’ distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine 〈40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species’ modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time.

Notes: The effect of natural selection on the mMEP-2* locus on measures of genetic divergence among Atlantic salmon populations was investigated by examining the pattern of change in the level of genetic differentiation (FST) averaged over loci when data on the mMEP-2* locus were either included or excluded. The level of FST among populations at various geographic scales was estimated from allele frequencies at up to four loci (sAAT-4*, IDDH-1*, IDHP-3*, and mMEP-2*). At smaller geographic scales (within river systems or limited geographic regions) levels of variance in mMEP-2* allele frequencies were reduced relative to mean levels. At larger geographic scales (across continents or the species range) variation in mMEP-2* allele frequencies was greater than mean levels. These results suggest an a priori hypothesis for the effect of selection on the mMEP-2* locus which may be applied in future studies on variation in protein coding or other (e.g. mini- and microsatellite) loci in the Atlantic salmon. It is recommended that estimates of gene flow among populations of the Atlantic salmon based on mean FST estimates which include data on the mMEP-2* locus should be viewed with caution.

Notes: Spatial variation at the diallelic Me-2 locus in the Atlantic salmon, Salmo salar L., was analysed using data from 95 river basins. Gene diversity was apportioned as follows: 63% within samples, 20% between North America and Europe, 14% between regions within continents and 3% within and among rivers within regions. On both continents the variation between rivers was clinal with latitude and highly correlated with summer temperatures. The correlation was detectable within and between rivers. These correlations strongly suggest that variation at the locus is subject to the direct or indirect effects of natural selection, and that caution is required when interpreting between-location differentiation at the locus as evidence for distinct stocks.