Monitoring Energetic Status of Lake Michigan Chinook Salmon Using Water Content as a
By Amber K. Peters, Michael L. Jones, Dale C. Honeyfield, James R. Bence
Journal of Great Lakes Research, Volume 33, Issue 1, 2007, Pages 253-263, ISSN 0380-1330, DOI: 10.3394/0380-1330(2007)33[253:MESOLM]2.0.CO;2.
Monitoring health indicators of fish populations can be an expensive and time consuming process. This study analyzed energy dynamics of Lake Michigan Chinook salmon using proximate composition analysis with the goal of determining an efficient method for monitoring the nutritional status of the population. Condition factor performed poorly as an indicator of whole-fish lipids (r2 = 0.07). Water content in a dorsal muscle plug was found to be correlated with whole-fish lipids (r2 = 0.50) for all samples. For the subset of samples that included small fish collected in the spring, the strength of the relationship between water content in a dorsal muscle plug and whole-fish lipids increased (r2 = 0.70). The metric of water content in a dorsal muscle plug was determined to provide an adequate surrogate of whole-fish lipid content and, therefore, overall nutritional status. We propose a monitoring program that involves collecting small individuals in the spring and reporting the proportion of samples with over 78% water content in muscle tissue. Small individuals collected in the spring had the lowest whole-fish lipid levels of any segment of the population and would be the most prone to nutritional stress; therefore we recommend focusing on them for monitoring.
Keywords: Chinook salmon; lipids; proximate composition analysis