Quantitative fatty acid signature analysis on New Zealand sea lions: model sensitivity and diet estimates

Meynier, Laureline; Morel, P. C. H.; Chilvers, B. Louise; Mackenzie, D. D. S.; Duignan, Pádraig J.

doi:10.1644/09-mamm-a-299.1

Cited by 46 publications

(55 citation statements)

References 51 publications

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“…Competition between sea lions and commercial fisheries may occur around the Auckland Islands (Meynier et al 2010) as reported for other large marine carni-vores interacting with fisheries (Alonzo et al 2003, Trites & Donnelly 2003, Drago et al 2009). However, the management of the Auckland Islands populations of New Zealand sea lions currently focuses on reducing the bycatch rate in squid fisheries but does not take into consideration the impact of resource competition with fisheries (Chilvers 2008).…”

Section: Fishing Competition: Impact On the Differences Observed And mentioning

confidence: 72%

“…Deaths of female New Zealand sea lions occur in commercial fisheries around the Auckland Islands and may contribute to this decline, alongside bacterial epizootics (Castinel et al 2007, Chilvers 2008. However, the cause of the decline is not well understood and potential competition for food resources with fisheries was recently revealed (Meynier et al 2010). Establishing if the remnant populations exploit marginal marine habitat may help increase the effectiveness of management measures for the remnant populations of this threatened species (Baker et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations

Augé¹,

Chilvers²,

Moore³

et al. 2011

Mar. Ecol. Prog. Ser.

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The New Zealand sea lion Phocarctos hookeri historically bred on the New Zealand mainland (South and North Islands). Subsistence hunting and later commercial sealing reduced its distribution to 3 breeding areas at the spatial edges of its historical distribution range, in the Auckland Islands (AI) and on Campbell Island. Here, we present foraging areas and foraging trips of female New Zealand sea lions from the Otago Peninsula, where a recolonising population has been found in the core of the historical range of the species. We compare the results with data from the AI in order to assess the theory that the spatial margin of a species' distribution represents the lower end of habitat suitability. Female New Zealand sea lions at Otago had significantly smaller foraging ranges than females at the AI (mean 65% Kernel ranges: 47 ± 25 km 2 versus 687 ± 109 km 2 ), made shorter foraging trips (mean 11.8 ± 2.3 h versus 66.2 ± 4.2 h), and spent 40% less time at sea overall. Juvenile females at Otago from age 2 onwards could access foraging grounds used by adult females nursing pups; this is unlikely to be the case at the AI due to the large distances and associated depths of foraging grounds. Our study illustrates the theory that spatial marginality is related to habitat marginality. Existing management measures to mitigate the impact of bycatch in fisheries on declining remnant colonies around the AI were modelled based on populations exploiting optimal habitat. They should now integrate this new information.

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Section: Fishing Competition: Impact On the Differences Observed And mentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations

Augé¹,

Chilvers²,

Moore³

et al. 2011

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…This is important given the not surprising observation that very high uncertainty in CCs in our study was associated with FAs in very low abundance in either predator or prey. Meynier et al (2010) similarly found that removal of FAs with relatively low mass improved the results of their QFASA diet predictions in New Zealand (NZ) fur seals Arctocephalus forsteri. Given that the choice of the FA set used can significantly affect diet estimates, subset selection should be thoroughly tested by the investigator.…”

Section: Importance Of Ccsmentioning

confidence: 87%

“…A mathematical model chooses the optimal proportion of prey that provides the 'best fit' (using Kulback-Liebler distances) to the predator's signature. QFASA has been applied to evaluate the prey of several marine homeotherms (Beck et al 2007, Thiemann et al 2007, Tucker et al 2009, Meynier et al 2010.…”

Section: Abstract: Fatty Acids · Quantitative Fatty Acid Signature Amentioning

confidence: 99%

“…Some studies are able to apply CCs derived from apparently closely related species (e.g. SSL for NZ sea lions; Meynier et al 2010), while others average a number of published CCs in an attempt to 'at least partially account for any uncertainty in this parameter' (Tucker et al 2009, p. 300). Others have had to make use of CCs derived from less clearly related species, such as substituting mink for polar bears (Thiemann et al 2007).…”

Section: Effect Of Predator Species On Ccsmentioning

confidence: 99%

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Effects of phylogeny and prey type on fatty acid calibration coefficients in three pinniped species: implications for the QFASA dietary quantification technique

Rosen¹,

Tollit²

2012

Mar. Ecol. Prog. Ser.

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Distance measures and optimization spaces in quantitative fatty acid signature analysis

Bromaghin

Rode

Budge

et al. 2015

Ecology and Evolution

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Quantitative fatty acid signature analysis has become an important method of diet estimation in ecology, especially marine ecology. Controlled feeding trials to validate the method and estimate the calibration coefficients necessary to account for differential metabolism of individual fatty acids have been conducted with several species from diverse taxa. However, research into potential refinements of the estimation method has been limited. We compared the performance of the original method of estimating diet composition with that of five variants based on different combinations of distance measures and calibration-coefficient transformations between prey and predator fatty acid signature spaces. Fatty acid signatures of pseudopredators were constructed using known diet mixtures of two prey data sets previously used to estimate the diets of polar bears Ursus maritimus and gray seals Halichoerus grypus, and their diets were then estimated using all six variants. In addition, previously published diets of Chukchi Sea polar bears were re-estimated using all six methods. Our findings reveal that the selection of an estimation method can meaningfully influence estimates of diet composition. Among the pseudopredator results, which allowed evaluation of bias and precision, differences in estimator performance were rarely large, and no one estimator was universally preferred, although estimators based on the Aitchison distance measure tended to have modestly superior properties compared to estimators based on the Kullback–Leibler distance measure. However, greater differences were observed among estimated polar bear diets, most likely due to differential estimator sensitivity to assumption violations. Our results, particularly the polar bear example, suggest that additional research into estimator performance and model diagnostics is warranted.

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Quantitative fatty acid signature analysis on New Zealand sea lions: model sensitivity and diet estimates

Cited by 46 publications

References 51 publications

Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations

Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations

Effects of phylogeny and prey type on fatty acid calibration coefficients in three pinniped species: implications for the QFASA dietary quantification technique

Distance measures and optimization spaces in quantitative fatty acid signature analysis

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