Physiologic Responses to Stress and Changes in Atlantic Bluefin Tuna (T. thynnus) Meat Color During Trap Fisheries Capture and Processing in Sardinia (W. Mediterranean)

Abstract

This study investigated plasma cortisol, lactate, and glucose as descriptors of hematological stressors; while the RGB color model using the percentage of monochromatic channels Red (R_p), Green (G_p), and Blue (B_p) was used for the analysis of muscular tissue of the Atlantic bluefin tuna, Thunnus thynnus. The experimental design provided a comparison of stressors and color channels Before and After the stress state and the analysis of variability of monochromatic channels for Fresh and Frozen specimens collected at three time intervals. Results showed a rapid accumulation of cortisol levels (from 73.3 ± 9.5 to 148.0 ± 21.2 ng/mL), lactate (from 5.7 ± 2.9 to 17.0 ± 2.2 μmol/mL), and glucose (from 83.5 ± 8.0 to 128.6 ± 19.3 mg/dL; p < 0.05). The colorimetric analysis highlighted that this accumulation did not in fact affect the color variability of muscle. Analysis of variance carried out to test the effects of color variability in Fresh samples showed significant differences for R_p, G_p, and B_p channels (p < 0.05), whereas no differences were found in Frozen samples. Highly significant differences (p < 0.001) were found comparing Fresh and Frozen for R_p and B_p, indicating a drop of these channels under diverse treatments.

Keywords:

• Atlantic bluefin tuna
• stress response
• meat color
• trap fishery
• Mediterranean Sea

Acknowledgments

A special thank you to Mr. Giuliano Greco and to all the Greco family for their welcome and logistic support at the Tonnara dell'Isola Piana (Ligure Sarda S.p.a.). We wish to express our gratitude to the staff of the Carloforte Tonnare diving center for their precious support during samplings in the trap chambers and also to Dr. Manca for blood and tissue analysis. Simon Lander revised the English version of the article. This work was supported financially by academic funds of the University of Cagliari (2010), project “Studio delle risposte fisiologiche primarie e secondarie del tonno rosso, Thunnus thynnus, causate dallo stress di cattura nelle tonnare sarde.”