MEPS 251:233-243 (2003)  -  doi:10.3354/meps251233

Effects of food consumption and temperature on growth rate and biochemical-based indicators of growth in early juvenile Atlantic cod Gadus morhua and haddock Melanogrammus aeglefinus

Myron A. Peck1,5,*, Lawrence J. Buckley2, Elaine M. Caldarone3, David A. Bengtson4

1Graduate School of Oceanography, University of Rhode Island, South Ferry Road, Narragansett, Rhode Island 02882, USA
2URI/NOAA CMER Program, Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, USA
3National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Narragansett Laboratory, 28 Tarzwell Drive, Narragansett, Rhode Island 02882, USA
4Department of Fisheries, Animal, and Veterinary Science, University of Rhode Island, Kingston, Rhode Island 02881, USA
5Present address: Institute of Hydrobiology and Fisheries Research, University of Hamburg, Olbersweg 24, 22767 Hamburg, Germany

ABSTRACT: The relationship between the somatic growth rate (G) and feeding level (unfed, intermediate, and maximum rations) of age-0 juvenile cod Gadus morhua and haddock Melanogrammus aeglefinus was quantified at different temperatures. Laboratory trials were conducted using 2 size-classes of cod (3.6 to 5.6 cm standard length [SL], and 8.1 to 12.4 cm SL) at 5, 8, 12, and 15°C, and 1 size-class of haddock (6.0 to 9.6 cm SL) at 8 and 12°C. The shape of the growth-feeding relationship was well described by a 3-parameter asymptotic function for cod and by a linear function for haddock (R2 range = 0.837 to 0.966). The growth rate and scope for growth were maximum at 12°C, whereas growth efficiency was greatest (26.0 to 32.2%) at temperatures between 5 and 8°C. Juvenile cod held at 15°C exhibited reduced rates and efficiencies of somatic growth compared to fish at other temperatures. Biochemical-based growth indicators for age-0 juveniles were calibrated from measurements of the amounts of RNA, DNA, and protein in white muscle samples. A multiple linear regression using RNA:DNA and temperature as independent variables explained a significant portion of the variability observed in G of juvenile cod (R2 = 0.716) and haddock (R2 = 0.637). This relationship may be useful in estimating recent growth of age-0 juvenile cod and haddock in the field.

KEY WORDS: Age-0 juvenile · Cod · Haddock · Feeding · Growth · RNA:DNA

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