We investigated the relationship between fat content and condition indices in Atlantic salmon Salmo salar parr sampled from a wild population on a seasonal basis. Condition of individual fish was indexed by residuals from the least-squares regressions of fat weight, dry weight, wet weight, and water weight (separately on fork length) as well as by relative condition factor, Fulton's condition factor, percent fat, and percent water. For all fish analyzed in the study (n = 284), residualized fat weight accounted for 81% of the variation in percent fat, for 58% of the variation in residualized dry weight, for 46% of the variation in residualized wet weight and relative condition factor, for 41% of the variation in Fulton's condition factor, for 35% of the variation in residualized water weight, and for 28% of the variation in percent water. All indices except Fulton's condition factor, residualized water weight, and percent water were significantly correlated with fat weight for all combinations of ...

Relationships among Fat Weight, Body Weight, Water Weight, and Condition Factors in Wild Atlantic Salmon Parr

Nutrient Partitioning and the Influence of Feed Composition on Body Composition

The effect of whole body lipid on early sexual maturation of 1+ age male chinook salmon (Oncorhynchus tshawytscha)

Traditional methods for determining the energy content of fish involve either chemical assays of lipid and protein levels (proximate analyses) or tissue combustion (bomb calorimetry). In studies of migrating Pacific salmon Oncorhynchus spp., entire fish need to be homogenized prior to analysis, as energy reserves are stored along a head-to-tail gradient and change along this gradient depending on the stage of upriver migration. The logistics and costs associated with transporting carcasses to the laboratory can be prohibitive. Also, many populations of Pacific salmon are at risk of extinction, so lethal sampling is often not an option. Few reliable and practical methods exist that enable rapid and nonlethal energy determinations of large fish in the field. We evaluated a handheld microwave energy meter as a means of estimating whole-body energy concentrations. In 2002 and 2003, we collected sockeye salmon O. nerka from several stocks during their coastal and upriver migration through the Fraser R...

A Nonlethal, Rapid Method for Assessing the Somatic Energy Content of Migrating Adult Pacific Salmon

Alternative reproductive tactics are commonly reported for salmonids (Pisces) and typically involve large migratory and small resident individuals. Variation in migratory tendency should reflect th ...

The role of the environment in partial migration : food availability affects the adoption of a migratory tactic in brown trout Salmo trutta

. A strong and significant positive correlation was observed between condition factor and total lipid content in immature Atlantic salmon, Salmo salar L., parr (0+) sampled at the same time. Condition factor can thus be used as a convenient non-lethal indicator of energy reserve status among immature salmonids.

G. W. Friars

Papers

Correlation between condition factor and total lipid content in Atlantic salmon, Salmo salar L., parr