Match!

Foraging ecology of silky sharks, Carcharhinus falciformis , captured by the tuna purse-seine fishery in the eastern Pacific Ocean

Published on Mar 1, 2015in Marine Biology2.134
· DOI :10.1007/s00227-014-2606-4
Leanne M. Duffy8
Estimated H-index: 8
(Inter-American Tropical Tuna Commission),
Robert J. Olson19
Estimated H-index: 19
(Inter-American Tropical Tuna Commission)
+ 3 AuthorsPetra M. Kuhnert20
Estimated H-index: 20
(CSIRO: Commonwealth Scientific and Industrial Research Organisation)
Sources
Abstract
Diet studies are an essential component of ecosystem-based approaches to fisheries management. In the eastern Pacific Ocean (EPO), the silky shark (Carcharhinus falciformis) is the most common species of shark in the bycatch of the tuna purse-seine fishery. A rare, comprehensive dataset of stomach contents of 786 silky sharks sampled in mostly tropical regions of the EPO (25°N–15°S; 79°W–162°W) during 1992–1994 and 2003–2005 was analyzed via classification tree and quantile regression methodologies to gain insight into its ecosystem role. Results suggest that the silky shark is an opportunistic predator that forages on a variety of prey. Broad-scale spatial and shark size covariates explained the feeding habits of silky sharks captured in sets on floating objects, primarily drifting fish-aggregating devices (FADs). A strong spatial shift in diet was identified by the tree analysis, with different foraging patterns in the eastern (inshore) and western (offshore) regions. Greater proportions of FAD-associated prey than non-FAD-associated prey were observed in the diet throughout the EPO, with the greatest proportion in the offshore region. Thus, silky sharks appear to take advantage of the associative behavior of prey fishes to increase their probability of encountering and capturing prey. Evaluation of prey–predator size relationships showed that maximum prey size increased with increasing silky shark size, but minimum prey size remained relatively constant across the range of shark sizes. Results such as these from spatially oriented analyses of predator feeding habits are essential for populating ecosystem models with space-based food webs, which otherwise suffer from generic representations of food webs.
  • References (98)
  • Citations (12)
📖 Papers frequently viewed together
15 Citations
1 Citations
119 Citations
78% of Scinapse members use related papers. After signing in, all features are FREE.
References98
Newest
299 Citations
Inference in quantile analysis has received considerable attention in the recent years. Linear quantile mixed models (Geraci and Bottai 2014) represent a flexible statistical tool to analyze data from sampling designs such as multilevel, spatial, panel or longitudinal, which induce some form of clustering. In this paper, I will show how to estimate conditional quantile functions with random effects using the R package lqmm. Modeling, estimation and inference are discussed in detail using a real ...
66 CitationsSource
#1Marco Geraci (UCL: University College London)H-Index: 19
#2Matteo Bottai (KI: Karolinska Institutet)H-Index: 49
Dependent data arise in many studies. Frequently adopted sampling designs, such as cluster, multilevel, spatial, and repeated measures, may induce this dependence, which the analysis of the data needs to take into due account. In a previous publication (Geraci and Bottai in Biostatistics 8:140–154, 2007), we proposed a conditional quantile regression model for continuous responses where subject-specific random intercepts were included to account for within-subject dependence in the context of lo...
109 CitationsSource
40 CitationsSource
The decline of predators in a variety of ecosystems has transformed community struc- ture through mesopredator release and trophic cascades. Elasmobranch fishes, one of the earth's most ubiquitous and diverse clade of predatory species, provide a model group for defining mar- ine predator roles. We consider whether the ecological predatory role of sharks is adequately defined by terrestrial-derived notions of apex- and mesopredation. Indeterminate growth and ontogenetic diet shifts may mean spec...
81 CitationsSource
126k Citations
#1Laurent DagornH-Index: 2
#2Nicolas BezH-Index: 15
Last. Emily WalkerH-Index: 4
view all 4 authors...
Natural floating objects (e.g., logs) have always been a component of the habitat of tropical tunas. However, the introduction of fish aggregating devices (FADs) modifies this environment. To assess the changes due to the deployment of FADs, we compared the spatial distribution of natural and artificial floating objects (FADs), using data from observers onboard tuna purse seine vessels in the Indian Ocean from December 2006 to December 2008. Although natural objects occur more commonly in waters...
14 CitationsSource
#1Jorge I. Figueroa-Zuñiga (UdeC: University of Concepción)H-Index: 2
#2Reinaldo B. Arellano-Valle (UC: Pontifical Catholic University of Chile)H-Index: 25
Last. Silvia L. P. Ferrari (USP: University of São Paulo)H-Index: 19
view all 3 authors...
This paper builds on recent research that focuses on regression modeling of continuous bounded data, such as proportions measured on a continuous scale. Specifically, it deals with beta regression models with mixed effects from a Bayesian approach. We use a suitable parameterization of the beta law in terms of its mean and a precision parameter, and allow both parameters to be modeled through regression structures that may involve fixed and random effects. Specification of prior distributions is...
40 CitationsSource
#1David A. Caron (SC: University of Southern California)H-Index: 64
#2David A. Hutchins (SC: University of Southern California)H-Index: 64
Microzooplankton dominate trophic interactions and biogeochemical processes at the base of pelagic marine food webs and so their responses to a changing ocean environment have potentially large implications for ocean ecosystem functioning. This diverse array of mostly protistan species constitutes an important source of phytoplankton and bacterial mortality, and contributes significantly to the food available to higher trophic levels by packaging minute prey into larger particle sizes that can b...
67 CitationsSource
Abstract Satellite remotely-sensed sea surface temperature (SST) and surface chlorophyll were used to estimate median phytoplankton cell size at monthly and 11 km2 resolution over the global ocean, 1998–2007. The temporal dynamics of median phytoplankton cell size were examined for the Pacific equatorial upwelling region and the subtropical oceans. For the equatorial upwelling region, cell size varied coherently with the El Nino Southern Oscillation with smaller (larger) median cell size during ...
40 CitationsSource
Cited By12
Newest
Source
Aspects of the reproductive biology of Argonauta nouryi Lorois, 1852 from the coast of Oaxaca, Mexico, were analysed. A total of 54 specimens with dorsal mantle length (ML) ranging from 6.2 to 41.1...
Source
#1Marco Geraci (USC: University of South Carolina)H-Index: 19
#2Alessio Farcomeni (University of Rome Tor Vergata)H-Index: 32
We propose a new family of linear mixed-effects models based on the generalized Laplace distribution. Special cases include the classical normal mixed-effects model, models with Laplace random effe...
Source
#1Michael I. Grant (JCU: James Cook University)H-Index: 1
#2Jonathan J. SmartH-Index: 7
Last. Colin A. Simpfendorfer (JCU: James Cook University)H-Index: 50
view all 7 authors...
The silky shark (Carcharhinus falciformis) is one of the most heavily fished tropical shark species globally, and currently there is increasing concern for its conservation status. However, large differences and ambiguity in life history parameter estimates among regions complicates its conservation and fisheries management. Using a Leslie matrix model that incorporated stochastic effects, we analysed the intraspecific demography of C. falciformis using available life history data from seven reg...
Source
#1Marco Geraci (USC: University of South Carolina)H-Index: 19
Abstract In regression applications, the presence of nonlinearity and correlation among observations offer computational challenges not only in traditional settings such as least squares regression, but also (and especially) when the objective function is nonsmooth as in the case of quantile regression. Methods are developed for the modelling and estimation of nonlinear conditional quantile functions when data are clustered within two-level nested designs. The proposed estimation algorithm is a ...
1 CitationsSource
#2Daniel M. CoffeyH-Index: 5
Last. Johanna L. K. Wren (Joint Institute for Marine and Atmospheric Research)H-Index: 6
view all 9 authors...
Abstract Understanding the habitat use and behavior of commercially exploited species throughout ontogeny is useful for devising effective management and conservation strategies. Differences in habitat use can often be exploited to separate target and non-target species, and determinations of home range size can inform the proper scale of conservation actions. In tropical tuna purse seine fisheries in the Pacific Ocean, juvenile silky sharks, Carcharhinus falciformis , comprise a large proportio...
Source
#1Diego Páez-Rosas (USFQ: Universidad San Francisco de Quito)H-Index: 7
#2Paul Insuasti-Zarate (University of Guayaquil)H-Index: 1
Last. Felipe Galván-Magaña (IPN: Instituto Politécnico Nacional)H-Index: 27
view all 4 authors...
: There is great concern about the future of sharks in Ecuador because of the lack of biological knowledge of most species that inhabit the region. This paper analyzes the feeding behavior of the pelagic thresher shark (Alopias pelagicus), the blue shark (Prionace glauca) and the silky shark (Carcharhinus falciformis) through the use of stable isotopes of carbon and nitrogen (δ13C and δ15N), with the aim of determining the degree of interaction between these species in the Galapagos Marine Reser...
2 CitationsSource
#1Nerea Lezama-OchoaH-Index: 5
#2Hilario MuruaH-Index: 22
Last. Igor SancristobalH-Index: 5
view all 8 authors...
This study examined diversity and habitat characteristics for bycatch assemblages in two different types of fishing (drifting fish aggregating devices sets and sets made on school of tunas) in the eastern Pacific Ocean (20oS-30oN and 70o-150oW) between 2005 and 2011 using biodiversity metrics and Generalized Additive Models. Bycatch information was based on data collected by onboard observers covering more than 80% of the purse seine fishing trips. Our results suggest that diversity and habitat ...
4 CitationsSource
#1Leanne M. Duffy (Inter-American Tropical Tuna Commission)H-Index: 8
#2Petra M. Kuhnert (CSIRO: Commonwealth Scientific and Industrial Research Organisation)H-Index: 20
Last. Frédéric Ménard (AMU: Aix-Marseille University)H-Index: 20
view all 17 authors...
Abstract Predator-prey interactions for three commercially valuable tuna species: yellowfin (Thunnus albacares), bigeye (T. obesus), and albacore (T. alalunga), collected over a 40-year period from the Pacific, Indian, and Atlantic Oceans, were used to quantitatively assess broad, macro-scale trophic patterns in pelagic ecosystems. Analysis of over 14,000 tuna stomachs, using a modified classification tree approach, revealed for the first time the global expanse of pelagic predatory fish diet an...
13 CitationsSource
#1Hayden T. Schilling (UNSW: University of New South Wales)H-Index: 4
#2Julian M. HughesH-Index: 10
Last. Iain M. Suthers (UNSW: University of New South Wales)H-Index: 36
view all 6 authors...
Pelagic mesopredators are abundant in many marine ecosystems and exert strong top-down influence on food webs. We explored the dietary niche of Pomatomus saltatrix in eastern Australia, using a classification tree analysis to identify key factors driving diet variation. P. saltatrix was shown to be an opportunistic generalist predator which exhibited increased baitfish consumption, and decreased crustacean consumption, with increasing size. The classification tree analysis showed that body size ...
4 CitationsSource