Spatiotemporal variability in bigeye vertical distribution in the Pacific Ocean

F. J. Abascal, T. Peatman, B. Leroy, S. Nicol, K. Schaefer, D. W. Fuller, J. Hampton

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Bigeye tuna are targeted by longliners and caught incidentally by purse seiners in the tropical Pacific. The spawning biomass has been reduced significantly from unexploited levels, necessitating management action in both the western and central Pacific and eastern Pacific. Stock assessments of bigeye tuna rely primarily on data from the fisheries; however, the vulnerability of the stock to these gears, and its spatiotemporal variability, remains poorly understood, requiring simplifying assumptions to be made in the stock assessments. We analyzed the vertical behavior of 65 bigeye tuna (estimated size range 48–130 cm fork length) tracked with archival tags in the equatorial Pacific Ocean and the Coral Sea, and found that fish depth shows a clear gradient with longitude, becoming progressively shallower from west to east. Additive mixed models were used to explore potential relationships of the depth behavior during both day and night to several life history and environmental variables. Swimming depths were most clearly related to the thermocline depth, the intensity of temperature stratification of the water column and fish size. The model predictions suggest strong relationships between fish depth and fisheries catch-per-unit-effort (CPUE) both spatially and temporally. In particular, we propose that El Niño-Southern Oscillation-driven changes in oceanography have a major influence on fish depth and longline CPUE, which could have substantial implications for stock assessments where longline CPUE is used as an index of abundance.

Original languageEnglish
Pages (from-to)371-379
Number of pages9
JournalFisheries Research
Volume204
DOIs
Publication statusPublished - 1 Aug 2018
Externally publishedYes

Fingerprint

Pacific Ocean
vertical distribution
Thunnus obesus
stock assessment
catch per unit effort
ocean
fish
fishery
fisheries
Coral Sea
Southern Oscillation
oceanography
longitude
bycatch
thermocline
temperature profiles
range size
oscillation
coral
vulnerability

Cite this

Abascal, F. J., Peatman, T., Leroy, B., Nicol, S., Schaefer, K., Fuller, D. W., & Hampton, J. (2018). Spatiotemporal variability in bigeye vertical distribution in the Pacific Ocean. Fisheries Research, 204, 371-379. https://doi.org/10.1016/j.fishres.2018.03.013
Abascal, F. J. ; Peatman, T. ; Leroy, B. ; Nicol, S. ; Schaefer, K. ; Fuller, D. W. ; Hampton, J. / Spatiotemporal variability in bigeye vertical distribution in the Pacific Ocean. In: Fisheries Research. 2018 ; Vol. 204. pp. 371-379.
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Abascal, FJ, Peatman, T, Leroy, B, Nicol, S, Schaefer, K, Fuller, DW & Hampton, J 2018, 'Spatiotemporal variability in bigeye vertical distribution in the Pacific Ocean', Fisheries Research, vol. 204, pp. 371-379. https://doi.org/10.1016/j.fishres.2018.03.013

Spatiotemporal variability in bigeye vertical distribution in the Pacific Ocean. / Abascal, F. J.; Peatman, T.; Leroy, B.; Nicol, S.; Schaefer, K.; Fuller, D. W.; Hampton, J.

In: Fisheries Research, Vol. 204, 01.08.2018, p. 371-379.

Research output: Contribution to journalArticle

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JF - Fisheries Research

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Abascal FJ, Peatman T, Leroy B, Nicol S, Schaefer K, Fuller DW et al. Spatiotemporal variability in bigeye vertical distribution in the Pacific Ocean. Fisheries Research. 2018 Aug 1;204:371-379. https://doi.org/10.1016/j.fishres.2018.03.013