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Martin Arostegui

Postdoctoral Scholar




B.S. Biology, Stanford University, 2014

Ph.D. Aquatic and Fishery Sciences, University of Washington, 2019

Martin Arostegui's Website



2000-present and while at APL-UW

Spatiotemporal segregation of ocean sunfish species (Molidae) in the eastern North Pacific

Arostegui, M.C., C.D. Braun, P.A. Woodworth-Jefcoats, D.R. Kobayashi, and P. Gaube, "Spatiotemporal segregation of ocean sunfish species (Molidae) in the eastern North Pacific," Mar. Ecol. Prog. Ser., 654, 109-125, doi:10.3354/meps13514, 2020.

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12 Nov 2020

Ocean sunfishes or molas (Molidae) are difficult to study as a result of their extensive movements and low densities in remote waters. In particular, little is known of the environmental niche separation and differences in the reproductive or movement ecology of molids in sympatry. We investigated spatiotemporal dynamics in the distribution of the common mola Mola mola, sharptail mola Masturus lanceolatus, and slender mola Ranzania laevis in the eastern North Pacific. We used observer data from a commercial fishery consisting of 85000+ longline sets spanning 24 yr, >50° in longitude, and >45° in latitude. Satellite altimetry analysis, species distribution modeling, and multivariate ordination revealed thermal niche separation, spatiotemporal segregation, and distinct community associations of the 3 molid species. Our quantitative findings suggest that the common mola is a more temperate species, while slender and sharptail mola are more (sub)tropical species, and that slender (and possibly also sharptail) mola undergo spawning migrations to the region around the Hawaiian Islands. In addition, we identified potential effects of fishing gear type on molid catch probability, an increasing trend in catch probability of a vulnerable species perhaps related to a shift in the distribution of fishing effort, and the possible presence in the fishery of a fourth molid species being misidentified as a congener, all of which are important conservation considerations for these enigmatic fishes.

Does lipid-correction introduce biases into isotopic mixing models? Implications for diet reconstruction studies

Arostegui, M.C., D.E. Schindler, and G.W. Holtgrieve, "Does lipid-correction introduce biases into isotopic mixing models? Implications for diet reconstruction studies," Oecologia, 191, 745-755, doi:10.1007/s00442-019-04525-7, 2019.

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30 Oct 2019

Carbon isotopes are commonly used in trophic ecology to estimate consumer diet composition. This estimation is complicated by the fact that lipids exhibit a more depleted carbon signature (δ13C) than other macromolecules, and are often found at different concentrations among individual organisms. Some researchers argue that lipids bias diet reconstructions using stable isotopes and should be accounted for prior to analysis in food web mixing models, whereas others contend that removing lipids may result in erroneous interpretations of the trophic interactions under study. To highlight this disagreement on best practices for applying δ13C in food web studies, we sampled the recent literature to determine the frequency and method of lipid-correction. We then quantified the potential magnitude and source of bias in mixing model results from a theoretical example and case study of diet reconstruction. The literature was split nearly evenly as to whether lipid-correction was applied to δ13C data in mixing model estimates of diet composition. Comparative mixing model scenarios demonstrated that lipid-correction can substantially alter the estimated diet composition and interpretation of consumer foraging habits. Given the lack of consensus on whether or not to lipid-correct prey and/or consumers, and the associated variation in mixing model results, we call for the establishment of a unified framework that will guide diet reconstruction in stable isotope ecology. Uncertainty in the prevalence of direct routing versus de novo synthesis of lipids across ecosystems, taxa, and trophic levels must be resolved to better guide treatment of lipids in isotope studies using carbon.

Movement ecology and stenothermy of satellite-tagged shortbill spearfish (Tetrapturus angustirostris)

Arostegui, M.C., P. Gaube, and C.D. Braun, "Movement ecology and stenothermy of satellite-tagged shortbill spearfish (Tetrapturus angustirostris)," Fish. Res., 215, 21-25, doi:10.1016/j.fishres.2019.03.005, 2019.

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1 Jul 2019

The shortbill spearfish (Tetrapturus angustirostris) is an understudied, istiophorid billfish primarily encountered as bycatch in pelagic commercial fisheries of the Indo-Pacific. The species is listed as data-deficient, and little is known of its biology, ecology, and population structure or status. We assessed the species' movement ecology and thermal niche with telemetry data from the first shortbill spearfishes ever outfitted with pop-up satellite archival transmitting tags (n = 3 with successfully transmitted data). Short (4–15 day) deployments offshore of the Island of Hawai'i revealed that spearfish primarily occupied the mixed layer, spending >90% of each 24-hr period between the surface and 100 m in water temperatures between 24–26°C. These individuals consistently exhibited vertical activity at night regardless of the prevailing lunar phase. Nocturnal movements throughout the mixed layer may enable shortbill spearfish to forage on mesopelagic species undergoing diel vertical migration and reduce trophic niche overlap with primarily diurnal, pelagic species. The narrow thermal distribution of shortbill spearfish in this study, almost exclusively within 2°C of sea surface temperature, suggests that they are more stenothermal than extra-generic istiophorid species.

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In The News

Spearfish insights from the IGFA great marlin race

HOT Bluewater Magazine

A recent article in HOT Bluewater Magazine highlighted the research programs on spearfish and the work being done by Dr. Arostegui who is also an IGFA Representative. To date, there have only been three published studies on spearfish with Dr. Arostegui publishing two of the three on Mediterranean spearfish and shortbill spearfish using IGMR satellite tag data.

1 Nov 2020

The rainbows of Bristol Bay

Cool Green Science, The Nature Conservancy, Matthew Miller

Bristol Bay is famous for sockeye Salmon. But APL-UW postdoctoral scholar Martin Arostegui studies the life histories of rainbow trout in streams and lakes of the Bristol Bay drainage. Rainbow trout diversity shows the interplay between habitat and genetics. “If you remove habitat diversity, you reduce life history diversity and thus the overall stability of the ecosystem,” says Arostegui.

9 Sep 2020

Billfish expedition to the Red Sea

Sport Fishing, Martin Arostegui

This was not a vacation trip but rather a research fishing expedition with the express goal of outfitting swordfish and other large pelagic fish in the Red Sea with satellite tags to study their movement behavior.

4 Feb 2020

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Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center