Standard Weight Equation for Lake Trout

Abstract

We developed a standard weight (W s ) equation for lake trout Salvelinus namaycush using the regression-line-percentile technique. Length and weight data from 58 populations of lake trout over most of the species* geographic range were used in development of the equations. In metric units (W St weight in grams; TL, total length in millimeters): logio^= -5.681 + 3.2462 logioTL. In English units (W s , pounds; TL, inches): logioW* = -3.778 + 3.2462 logi 0 TL. A systematic change in relative weight with increasing fish length was not evident.The use of condition indices in assessing the relative plumpness offish in a population is widespread in fisheries management. Recently, the concept of relative weight (W r ) has been applied frequently by fisheries managers (Wege and Anderson 1978) when standard weight (W s ) equations are available for target species (Murphy et al. 1991). Murphy et al. (1990) developed the regressionline-percentile (RLP) technique as a method for deriving standard-weight equations, and they recommended its use as a standardized approach for deriving W s equations. We used the RLP technique to develop a W s equation for lake trout Salvelinus namaycush. This is the first proposed W s equation for a salmonid species that has been developed using the RLP technique.The lake trout is native to North America, its range coinciding with the limits of Pleistocene glaciation (Scott and Crossman 1973). The lake trout is found throughout Canada, and in the United States it is native to several northerly states-Alaska,

Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator

“…Newly captured fish received a tag for future identification. Condition was estimated as a percentage of standard weight specific for lake trout (48). We identified 141 instances in which an individual fish was captured in consecutive years during the study period.…”

Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake

“…Cutthroat trout wet mass was calculated from TL using data from 19,213 cutthroat trout from Yellowstone Lake (Yellowstone National Park, unpublished data). Lake trout wet mass was estimated from TL using a published relationship predicting the 75th percentile of mass (Piccolo et al 1993). Dry mass of salmonids was calculated as 22% of wet mass (Cyr and Peters 1996).…”

Life history differences between fat and lean morphs of lake charr (Salvelinus namaycush) in Great Slave Lake, Northwest Territories, Canada

“…The onset of maturity in many lake charr populations is related to both body size and age Table 2 Slope of log 10 -transformed weight-length relationships (b), predicted weight of a 500-mm fish (W 500 = kg), annual survival (S), asymptotic length (L ? = mm), early growth rate (x = mm/year), length at 50% maturity (L50 = mm), and age at 50% maturity (A50 = years) for native lake trout populations from North America (mean, standard deviation = SD, coefficient of variation = CV, and number of populations = N; Dubois & Lageaux, 1968;Healey, 1978;Piccolo et al, 1993;Trippel, 1993;Martin & Olver, 1980;Shuter et al, 1998;Mills et al, 2002;McDermid et al, 2010;Hansen et al, 2012) and percentiles of each metric's cumulative North American distribution for lean and fat lake trout morphs captured in Great Slave Lake, Northwest Territories, Canada, during 1-3 August 2002, 6-11 August 2005, and 26 July-3 August 2010 (Table 1; (Martin & Olver, 1980). In Great Slave Lake, lean and fat morphs shift from benthic to pelagic feeding with increasing body size: small lake charr (\430 mm TL) are benthic feeders that overlap in depth distribution, but partition resources within depths, whereas large lake charr ([430 mm TL) are pelagic feeders that occupy shallow (lean) or deep (fat) depths, and partition resources in depths they inhabit (Zimmerman et al, 2009).…”