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RECA: Proximate Composition

ABL Home
Recruitment, Energetics, & Coastal Assessment
Recruitment Energetics:
Fish Processing and Food Habits
Proximate Composition
Coastal Assessment
Division Activities:
Data Sets
Pacific Herring (Clupea pallasi)
Pacific herring (Clupea pallasi).

Proximate analysis is used to estimate the relative amounts protein, lipid, water, ash and carbohydrate in an organism. Protein, lipid and carbohydrate each contribute to the total energy content of an organism while water and ash only contribute mass. Consequently, the total energy content of a specimen can be reconstructed from its proximate composition. Energy content is frequently used as an expression of a fish’s condition or health status. However, the relative contributions of lipid, protein and carbohydrate to a fish’s total energy vary in response to specific life history demands.

In our lab, we examine proximate composition of marine forage species to understand the interplay between the constraints imposed by the environment and life history strategy on observed energy flux.

Seasonal Lipid Content of Pacific Herring
Body composition of planktivorous forage species fluctuates significantly at high latitudes as a result of seasonal periods of food availability and spawning expenditures. Above, the seasonal whole-body lipid content of Pacific herring (Clupea pallasi) (mean ± 95% confidence interval) expressed on a wet-mass basis is depicted, where vertical dashed lines indicated spawning periods.

Graph displaying Seasonal Lipid Content of Pacific Herring
Seasonal Lipid Content of Pacific Herring
Analysis of Energy Content: Bomb Calorimetry vs. Calculation
Graphs displaying energy allomet of juvenile capelin life stages of capelin
Life stages of capelin (Mallotus vilosus).

Analysis of Energy Content: Bomb Calorimetry vs Calculation
Energy content determined directly from bomb calorimetry and indirectly calculated using calorific equivalents for protein and energy yield similar results. In our lab, we regularly estimate energy content via calculation because of the powerful information incorporated in proximate composition data.

Ron Heintz
Auke Bay Laboratories
Alaska Fisheries Science Center, NOAA Fisheries

Ted Stevens Marine Research Institute
17109 Pt Lena Loop Rd
Juneau AK 99801
(907) 789-6058

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