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Direct quantification of energy intake in an apex marine predator suggests physiology is a key driver of migrations.

Whitlock RE, Hazen EL, Walli A, Farwell C, Bograd SJ, Foley DG, Castleton M, Block BA - Sci Adv (2015)

Bottom Line: We quantified the energy intake of Pacific bluefin tuna in the California Current using a laboratory-validated model, the first such measurement in a wild marine predator.Movements were not always consistent with maximizing energy intake: the Pacific bluefin move out of energy rich waters both in late summer and winter, coincident with rising and falling water temperatures, respectively.We hypothesize that temperature-related physiological constraints drive migration and that Pacific bluefin tuna optimize energy intake within a range of optimal aerobic performance.

View Article: PubMed Central - PubMed

Affiliation: Tuna Research and Conservation Center, Stanford University, Hopkins Marine Station, Oceanview Boulevard, Pacific Grove, CA 93950, USA. ; Sveriges Lantbruksuniversitet, Sötvattenslaboratoriet, Stångholmsvägen 2, Drottningholm 178 93, Sweden.

ABSTRACT
Pacific bluefin tuna (Thunnus orientalis) are highly migratory apex marine predators that inhabit a broad thermal niche. The energy needed for migration must be garnered by foraging, but measuring energy intake in the marine environment is challenging. We quantified the energy intake of Pacific bluefin tuna in the California Current using a laboratory-validated model, the first such measurement in a wild marine predator. Mean daily energy intake was highest off the coast of Baja California, Mexico in summer (mean ± SD, 1034 ± 669 kcal), followed by autumn when Pacific bluefin achieve their northernmost range in waters off northern California (944 ± 579 kcal). Movements were not always consistent with maximizing energy intake: the Pacific bluefin move out of energy rich waters both in late summer and winter, coincident with rising and falling water temperatures, respectively. We hypothesize that temperature-related physiological constraints drive migration and that Pacific bluefin tuna optimize energy intake within a range of optimal aerobic performance.

No MeSH data available.


Related in: MedlinePlus

Correlates of average daily energy intake (kcal) in tagged Pacific bluefin tuna.Estimated response curves (smooth terms) and year effects from the final GAMM. (A to D) SST (A), length of the tagged tuna (B), chlorophyll-a concentration (C), and isothermal layer depth (D). Dashed lines represent 95% confidence limits. Vertical axes are partial responses (estimated, centered smooth functions) on the scale of the linear predictor.
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Figure 5: Correlates of average daily energy intake (kcal) in tagged Pacific bluefin tuna.Estimated response curves (smooth terms) and year effects from the final GAMM. (A to D) SST (A), length of the tagged tuna (B), chlorophyll-a concentration (C), and isothermal layer depth (D). Dashed lines represent 95% confidence limits. Vertical axes are partial responses (estimated, centered smooth functions) on the scale of the linear predictor.

Mentions: Environmental conditions, spatiotemporal information, and the length of the tagged fish explained a relatively large proportion of the variation in estimated energy intake (adjusted R2 of 34%) in a generalized additive mixed model (GAMM) (Figs. 4 and 5). Spatial patterns in model-predicted energy intake reflected patterns observed in the raw data (Figs. 1, 3, and 4). Over the year, predicted energy intake was highest in June and July and lowest in December (Fig. 4 and figs. S5 and S6). In autumn and winter (September to March), predicted energy intake increased with latitude, with the highest values predicted north of 32°N in waters off central and southern California (Fig. 4 and fig. S6). In contrast, predicted energy intake was highest at lower latitudes in summer (June and July) (Fig. 4).


Direct quantification of energy intake in an apex marine predator suggests physiology is a key driver of migrations.

Whitlock RE, Hazen EL, Walli A, Farwell C, Bograd SJ, Foley DG, Castleton M, Block BA - Sci Adv (2015)

Correlates of average daily energy intake (kcal) in tagged Pacific bluefin tuna.Estimated response curves (smooth terms) and year effects from the final GAMM. (A to D) SST (A), length of the tagged tuna (B), chlorophyll-a concentration (C), and isothermal layer depth (D). Dashed lines represent 95% confidence limits. Vertical axes are partial responses (estimated, centered smooth functions) on the scale of the linear predictor.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643779&req=5

Figure 5: Correlates of average daily energy intake (kcal) in tagged Pacific bluefin tuna.Estimated response curves (smooth terms) and year effects from the final GAMM. (A to D) SST (A), length of the tagged tuna (B), chlorophyll-a concentration (C), and isothermal layer depth (D). Dashed lines represent 95% confidence limits. Vertical axes are partial responses (estimated, centered smooth functions) on the scale of the linear predictor.
Mentions: Environmental conditions, spatiotemporal information, and the length of the tagged fish explained a relatively large proportion of the variation in estimated energy intake (adjusted R2 of 34%) in a generalized additive mixed model (GAMM) (Figs. 4 and 5). Spatial patterns in model-predicted energy intake reflected patterns observed in the raw data (Figs. 1, 3, and 4). Over the year, predicted energy intake was highest in June and July and lowest in December (Fig. 4 and figs. S5 and S6). In autumn and winter (September to March), predicted energy intake increased with latitude, with the highest values predicted north of 32°N in waters off central and southern California (Fig. 4 and fig. S6). In contrast, predicted energy intake was highest at lower latitudes in summer (June and July) (Fig. 4).

Bottom Line: We quantified the energy intake of Pacific bluefin tuna in the California Current using a laboratory-validated model, the first such measurement in a wild marine predator.Movements were not always consistent with maximizing energy intake: the Pacific bluefin move out of energy rich waters both in late summer and winter, coincident with rising and falling water temperatures, respectively.We hypothesize that temperature-related physiological constraints drive migration and that Pacific bluefin tuna optimize energy intake within a range of optimal aerobic performance.

View Article: PubMed Central - PubMed

Affiliation: Tuna Research and Conservation Center, Stanford University, Hopkins Marine Station, Oceanview Boulevard, Pacific Grove, CA 93950, USA. ; Sveriges Lantbruksuniversitet, Sötvattenslaboratoriet, Stångholmsvägen 2, Drottningholm 178 93, Sweden.

ABSTRACT
Pacific bluefin tuna (Thunnus orientalis) are highly migratory apex marine predators that inhabit a broad thermal niche. The energy needed for migration must be garnered by foraging, but measuring energy intake in the marine environment is challenging. We quantified the energy intake of Pacific bluefin tuna in the California Current using a laboratory-validated model, the first such measurement in a wild marine predator. Mean daily energy intake was highest off the coast of Baja California, Mexico in summer (mean ± SD, 1034 ± 669 kcal), followed by autumn when Pacific bluefin achieve their northernmost range in waters off northern California (944 ± 579 kcal). Movements were not always consistent with maximizing energy intake: the Pacific bluefin move out of energy rich waters both in late summer and winter, coincident with rising and falling water temperatures, respectively. We hypothesize that temperature-related physiological constraints drive migration and that Pacific bluefin tuna optimize energy intake within a range of optimal aerobic performance.

No MeSH data available.


Related in: MedlinePlus