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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

HIF in relation to SST, latitude, and chl-a.(A) Three-dimensional contour plot for observed daily energy intake in 2003 (interpolated and smoothed for visualization) against mean daily SST and latitude. (B) Latitudinal distribution of 144 tagged bluefin tuna in the California Current, 2002 to 2007. (Top) Date versus latitude with remotely sensed mean daily SST (°C) indicated by the color scale. (Center) Date versus latitude with median daily energy intake (kcal) indicated by the color scale. (Bottom) Date versus latitude with the logarithm of median daily chlorophyll-a concentration (mg m−3) indicated by the color scale. The solid black line in each panel denotes the median latitude of archival tagged tuna, whereas the dashed lines show the 2.5th and 97.5th percentiles for the latitudinal distribution.
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Figure 3: HIF in relation to SST, latitude, and chl-a.(A) Three-dimensional contour plot for observed daily energy intake in 2003 (interpolated and smoothed for visualization) against mean daily SST and latitude. (B) Latitudinal distribution of 144 tagged bluefin tuna in the California Current, 2002 to 2007. (Top) Date versus latitude with remotely sensed mean daily SST (°C) indicated by the color scale. (Center) Date versus latitude with median daily energy intake (kcal) indicated by the color scale. (Bottom) Date versus latitude with the logarithm of median daily chlorophyll-a concentration (mg m−3) indicated by the color scale. The solid black line in each panel denotes the median latitude of archival tagged tuna, whereas the dashed lines show the 2.5th and 97.5th percentiles for the latitudinal distribution.

Mentions: Wild juvenile Pacific bluefin tuna fed successfully on 91% of days (SE, 0.15%). HIF magnitude measured daily varied between 0 and 4106 kcal, with a median of 820 kcal (mean ± SD, 855 ± 540 kcal). The daily sea surface temperature (SST) in the CCLME as measured by archival tags varied from 11.0° to 26.7°C (mean ± SD, 17.2° ± 1.8°C) (Fig. 3). Mean thermal excess (the difference between peritoneal and ambient temperature) at the onset of feeding events was 3.7°C (± 2.3°C); the maximum 13.8°C. Energy intake and thermal excess were positively correlated with body size as measured by the curved fork length (CFL) of tagged tunas [Pearson correlation coefficients, ρ = 0.12 (HIF), ρ = 0.18 (thermal excess); both significantly different from 0 (P < 0.001)].


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)

HIF in relation to SST, latitude, and chl-a.(A) Three-dimensional contour plot for observed daily energy intake in 2003 (interpolated and smoothed for visualization) against mean daily SST and latitude. (B) Latitudinal distribution of 144 tagged bluefin tuna in the California Current, 2002 to 2007. (Top) Date versus latitude with remotely sensed mean daily SST (°C) indicated by the color scale. (Center) Date versus latitude with median daily energy intake (kcal) indicated by the color scale. (Bottom) Date versus latitude with the logarithm of median daily chlorophyll-a concentration (mg m−3) indicated by the color scale. The solid black line in each panel denotes the median latitude of archival tagged tuna, whereas the dashed lines show the 2.5th and 97.5th percentiles for the latitudinal distribution.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: HIF in relation to SST, latitude, and chl-a.(A) Three-dimensional contour plot for observed daily energy intake in 2003 (interpolated and smoothed for visualization) against mean daily SST and latitude. (B) Latitudinal distribution of 144 tagged bluefin tuna in the California Current, 2002 to 2007. (Top) Date versus latitude with remotely sensed mean daily SST (°C) indicated by the color scale. (Center) Date versus latitude with median daily energy intake (kcal) indicated by the color scale. (Bottom) Date versus latitude with the logarithm of median daily chlorophyll-a concentration (mg m−3) indicated by the color scale. The solid black line in each panel denotes the median latitude of archival tagged tuna, whereas the dashed lines show the 2.5th and 97.5th percentiles for the latitudinal distribution.
Mentions: Wild juvenile Pacific bluefin tuna fed successfully on 91% of days (SE, 0.15%). HIF magnitude measured daily varied between 0 and 4106 kcal, with a median of 820 kcal (mean ± SD, 855 ± 540 kcal). The daily sea surface temperature (SST) in the CCLME as measured by archival tags varied from 11.0° to 26.7°C (mean ± SD, 17.2° ± 1.8°C) (Fig. 3). Mean thermal excess (the difference between peritoneal and ambient temperature) at the onset of feeding events was 3.7°C (± 2.3°C); the maximum 13.8°C. Energy intake and thermal excess were positively correlated with body size as measured by the curved fork length (CFL) of tagged tunas [Pearson correlation coefficients, ρ = 0.12 (HIF), ρ = 0.18 (thermal excess); both significantly different from 0 (P < 0.001)].

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