A taste for squid: the diet of sperm whales stranded in Greece, Eastern Mediterranean

Foskolos, Ilias; Koutouzi, Niki; Polychronidis, Lysimachos; Alexiadou, Paraskevi; Frantzis, Alexandros

doi:10.1016/j.dsr.2019.103164

Cited by 16 publications

(15 citation statements)

References 61 publications

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“…Most of the bony fishes known to be consumed by S. coeruleoalba and T. truncatus are widely distributed in the gulf and Ionian area [43,59]. Despite the lack of local diet information on cetaceans representing a critical gap to be better filled by future studies, the analysis highlights the availability of important food resources that fit the trophic needs of the resident odontocete populations, in line with observations reported in other locations, especially the Aegean Sea, even though these displayed different levels of abundance [72,78], and the Ligurian Sea [76,77]. This evidence supports the robustness of the here applied modelling approach.…”

Section: Discussionsupporting

confidence: 72%

“…In particular, 8 domains were defined: Planktonic groups (Plank), Pelagics of shelf (PEL-SH), Pelagics of slope (PEL-SL), Demersals of shelf (DEM-SH), Demersals of slope (DEM-SL), Benthopelagic groups of shelf (BP-SH), Benthopelagic groups of slope (BP-SL) and Discards (Table 2). Concerning cetaceans' trophic traits, feeding habits were described by means of quantitave information (expressed as % weight) derived from stomach content analysis carried out in several Mediterranean areas, such as the North Aegean Sea [72], Western Mediterranean areas [73,74], Ionian Sea [75], Ligurian Sea [76,77], and Greek seas [78]. These different pieces of information were aggregated providing an average diet for each cetacean species [35].…”

Section: Data Analysis and Ecological Indicatorsmentioning

confidence: 99%

“…Prey consumed by odontocetes (Pm = P. macrocephalus; Gg = G. griseus; Sc = S. coeruleoalba; Tt = T. truncatus) obtained from the literature (Ref. ):[72][73][74][75][76][77][78]97,124,125]. The prey biomass values (B kg km −2 ; %) refer to those sampled in the Gulf of Taranto by means of MEDITS experimental hauls during the period 1995-2018.…”

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confidence: 99%

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Addressing Cetacean–Fishery Interactions to Inform a Deep-Sea Ecosystem-Based Management in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

Ricci

Manea

Cipriano

et al. 2021

JMSE

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Understanding of cetaceans’ trophic role and the quantification of their impacts on the food web is a critical task, especially when data on their prey are linked to deep-sea ecosystems, which are often exposed to excessive exploitation of fishery resources due to poor management. This aspect represents one of the major issues in marine resource management, and trade-offs are needed to simultaneously support the conservation of cetaceans and their irreplaceable ecological role, together with sustainable fishing yield. In that regard, food web models can represent useful tools to support decision-making processes according to an ecosystem-based management (EBM) approach. This study provides a focus on the feeding activity occurrence and the trophic interactions between odontocetes and the fishery in the marine food web of the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea), by zooming in on cetaceans’ prey of commercial interest. In particular, the quantification of trophic impacts is estimated using a food web mass-balance model that integrates information on the bathymetric displacement of both cetaceans’ prey and fishing activity. The results are discussed from a management perspective to guide future research and knowledge enhancement activities as well as support the implementation of an EBM approach.

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Section: Discussionsupporting

confidence: 72%

Section: Data Analysis and Ecological Indicatorsmentioning

confidence: 99%

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Addressing Cetacean–Fishery Interactions to Inform a Deep-Sea Ecosystem-Based Management in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

Ricci

Manea

Cipriano

et al. 2021

JMSE

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“…Drawing from other areas of the Mediterranean Sea, the preferred habitat of sperm whales is the continental slope [24,60,61], where the interaction between currents and bathymetry results in increased productivity and spatial aggregation of sperm whales' prey. The only study on the species' ecology in the Aegean Sea has focused on the analysis of stomach contents from four stranded sperm whales [62]. The most important preys were small individuals of three deepwater squids that are not currently targeted by fisheries [62].…”

mentioning

confidence: 99%

“…The only study on the species' ecology in the Aegean Sea has focused on the analysis of stomach contents from four stranded sperm whales [62]. The most important preys were small individuals of three deepwater squids that are not currently targeted by fisheries [62].…”

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confidence: 99%

Current State of Knowledge and Conservation Perspectives on the Cetaceans of the Aegean Sea

Foskolos

Gkikopoulou

Frantzis³

2020

The Handbook of Environmental Chemistry

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The underwater habitat complexity of the Aegean Sea renders it home to a diversity of cetacean species. From shallow-diving piscivores to teuthophagous deep divers, this sea hosts seven regular cetacean species (Delphinidae, Phocoenidae, Physeteridae, and Ziphiidae), while five more species have been reported as visitors. Despite this high biodiversity, little is known about this taxon, with most available information referring only to presence data. Due to an ever-increasing human development in the area, seven threats can be identified so far: interactions with

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Bioenergetic modelling of a marine top predator's responses to changes in prey structure

Silva,

Oliveira,

Prieto

et al. 2024

Ecology and Evolution

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Determining how animals allocate energy, and how external factors influence this allocation, is crucial to understand species' life history requirements and response to disturbance. This response is driven in part by individuals' energy balance, prey characteristics, foraging behaviour and energy required for essential functions. We developed a bioenergetic model to estimate minimum foraging success rate (FSR), that is, the lowest possible prey capture rate for individuals to obtain the minimum energy intake needed to meet daily metabolic requirements, for female sperm whale (Physeter macrocephalus). The model was based on whales' theoretical energetic requirements using foraging and prey characteristics from animal‐borne tags and stomach contents, respectively. We used this model to simulate two prey structure change scenarios: (1) decrease in mean prey size, thus lower prey energy content and (2) decrease in prey size variability, reducing the variability in prey energy content. We estimate the whales need minimum of ~14% FSR to meet their energetic requirements, and energy intake is more sensitive to energy content changes than a decrease in energy variability. To estimate vulnerability to prey structure changes, we evaluated the compensation level required to meet bioenergetic demands. Considering a minimum 14% FSR, whales would need to increase energy intake by 21% (5–35%) and 49% (27–67%) to compensate for a 15% and 30% decrease in energy content, respectively. For a 30% and 50% decrease in energy variability, whales would need to increase energy intake by 13% (0–23%) and 24% (10–35%) to meet energetic demands, respectively. Our model demonstrates how foraging and prey characteristics can be used to estimate impact of changing prey structure in top predator energetics, which can help inform bottom‐up effects on marine ecosystems. We showed the importance of considering different FSR in bioenergetics models, as it can have decisive implications on estimates of energy acquired and affect the conclusions about top predator's vulnerability to possible environmental fluctuations.

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A taste for squid: the diet of sperm whales stranded in Greece, Eastern Mediterranean

Cited by 16 publications

References 61 publications

Addressing Cetacean–Fishery Interactions to Inform a Deep-Sea Ecosystem-Based Management in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

Addressing Cetacean–Fishery Interactions to Inform a Deep-Sea Ecosystem-Based Management in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

Current State of Knowledge and Conservation Perspectives on the Cetaceans of the Aegean Sea

Bioenergetic modelling of a marine top predator's responses to changes in prey structure

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