SUMMARYUsing implanted archival tags, we examined the effects of meal caloric value, food type (sardine or squid) and ambient temperature on the magnitude and duration of the heat increment of feeding in three captive juvenile Pacific bluefin tuna. The objective of our study was to develop a model that can be used to estimate energy intake in wild fish of similar body mass. Both the magnitude and duration of the heat increment of feeding (measured by visceral warming) showed a strong positive correlation with the caloric value of the ingested meal. Controlling for meal caloric value, the extent of visceral warming was significantly greater at lower ambient temperature. The extent of visceral warming was also significantly higher for squid meals compared with sardine meals. By using a hierarchical Bayesian model to analyze our data and treating individuals as random effects, we demonstrate how increases in visceral temperature can be used to estimate the energy intake of wild Pacific bluefin tuna of similar body mass to the individuals used in our study. Supplementary material available online at

SUMMARYThe bluefin tuna heart remains at ambient water temperature (T a ) but must supply blood to warm regions of the body served by countercurrent vascular heat exchangers. Despite this unusual physiology, inherent difficulties have precluded an understanding of the cardiovascular responses to T a in free-swimming bluefin tunas. We measured the heart rate (f H ) responses of two captive Pacific bluefin tunas (Thunnus orientalis; 9.7 and 13.3kg) over a cumulative period of 40days. Routine f H during fasting in the holding tank at a T a of 20°C was 45.1±8.0 and 40.7±6.5beatsmin −1 for Tuna 1 and Tuna 2, respectively. f H decreased in each fish with a Q 10 temperature coefficient of 2.6 (Tuna 1) and 3.1 (Tuna 2) as T a in the tank was slowly decreased to 15°C (~0.4°Ch Supplementary material available online at

Methods to produce fixation between the tunica albuginea (visceral tunica vaginalis) and surrounding structures were used in Sprague-Dawley rats as an experimental model of orchiopexy to prevent testicular torsion. Eversion of the parietal tunica vaginalis without suture, or with absorbable or nonabsorbable suture produced excellent scarification, as did the use of talc. Absorbable and nonabsorbable suture, when placed between the parietal tunica vaginalis and tunica albuginea (visceral tunica vaginalis), produced only minor degrees of inflammation. Tetracycline instillation similarly failed to produce a significant inflammatory response.

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