Feeding habits of the bullet tuna Auxis rochei in the southern Tyrrhenian Sea

Author(s):  
E. Mostarda ◽  
D. Campo ◽  
L. Castriota ◽  
V. Esposito ◽  
M.P. Scarabello ◽  
...  

A total of 235 bullet tunas (Auxis rochei) was caught off the north-eastern coast of Sicily between March 2003 and March 2004 for the purpose of studying their feeding habits. The fish were caught by means of an experimental surface gill-net during fishing surveys carried out on a monthly basis. The stomach contents were analysed and the prey identified, counted and weighed. The importance of the different prey types was assessed utilizing several feeding indices while possible size-related changes of the diet composition were highlighted by means of hierarchical cluster analysis, nMDS and SIMPER analysis. The results of this study showed that the bullet tuna is an epipelagic off-shore predator feeding on whatever abundant resource is available in the environment with a preference for planktonic crustaceans, small cephalopods and fish larvae. Among crustaceans, hyperiidean amphipods were the most important prey, with Anchylomera blossevillei as the dominant species, followed by the euphausiacean Stylocheiron maximum. Among cephalopods, Heteroteuthis dispar was recorded frequently while fish larvae showed high values of all indices. All prey were pelagic organisms. A size-related change in the diet composition was observed, even if it seemed related to the temporal fluctuations of the zooplanktonic assemblage in the environment. The average prey weight per stomach increased significantly in the larger predators which mostly fed on fish larvae belonging to several commercially important demersal and pelagic species.

Author(s):  
Marco Stagioni ◽  
Stefano Montanini ◽  
Maria Vallisneri

The stomach contents of 1096 specimens of Chelidonichthys lucerna were examined in order to analyse their diet composition according to fish size, sex, depth and season. Sampling was carried out from May 2005 to March 2007 during several bottom trawl surveys in the Adriatic Sea (north-east Mediterranean). Feeding activity was more intense in juveniles than in adults. The most important prey was Crustacea (mainly Decapoda: Brachyura, such as Goneplax rhomboides, Liocarcinus spp., Philocheras spp.) and Teleostei (mainly European anchovy Engraulis encrasicolus and black goby Gobius niger). There was no difference between male and female diet. Feeding habits varied with size, with fish dominating the stomach contents of larger specimens. Finally, fish increased in winter and crustaceans in summer. Chelidonichthys lucerna shows a generalist and opportunistic foraging behaviour, preying mainly epibenthic and nectobenthic organisms.


2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Santiago A. Barbini ◽  
Luis O. Lucifora

ABSTRACT The eyespot skate, Atlantoraja cyclophora, is an endemic species from the southwestern Atlantic, occurring from Rio de Janeiro, Brazil, to northern Patagonia, Argentina. The feeding habits of this species, from off Uruguay and north Argentina, were evaluated using a multiple hypothesis modelling approach. In general, the diet was composed mainly of decapod crustaceans, followed by teleost fishes. Molluscs, mysidaceans, amphipods, isopods, lancelets and elasmobranchs were consumed in lower proportion. The consumption of shrimps drecreased with increasing body size of A. cyclophora. On the other hand, the consumption of teleosts increased with body size. Mature individuals preyed more heavily on crabs than immature individuals. Teleosts were consumed more in the south region (34º - 38ºS) and crabs in the north region (38º - 41ºS). Shrimps were eaten more in the warm season than in the cold season. Prey size increased with increasing body size of A. cyclophora , but large individuals also consumed small teleosts and crabs. Atlantoraja cyclophora has demersal-benthic feeding habits, shifts its diet with increasing body size and in response to seasonal and regional changes in prey availability and distribution.


2015 ◽  
Vol 17 (1) ◽  
pp. 216 ◽  
Author(s):  
B. ZORICA ◽  
V. ČIKES KEČ ◽  
O. VIDJAK ◽  
I. MLADINEO ◽  
D. EZGETA BALIČ

We examined the stomach contents of two of the most economically and ecologically important small pelagic fish species, the sardine, Sardina pilchardus and the anchovy, Engraulis encrasicolus, obtained monthly from commercial purse-seine catches operating on Croatian fishing grounds during a one-year period (January–December, 2011). Both species generally showed a similar diet, with copepod and decapod larvae as dominant prey groups. The composition of anchovy and sardine stomach contents was not size- or sex-related, but throughout the year, a significant difference in diet composition was observed for each species as well as between species. Two gastrointerstinal helminths; the digenean Parahemiurus merus and nematode Hysterothylacium aduncum, were recorded during the stomach content analysis. Differences in population dynamics between the two parasites are congruent with differences in the prey composition of sardine and anchovy, reflecting fine-tuned interactions in the trophic web between parasites and intermediate or paratenic hosts included in the sardine and anchovy diet.


Author(s):  
M. Carolina Romero ◽  
Gustavo A. Lovrich ◽  
Federico Tapella ◽  
Sven Thatje

Munida subrugosa is the most abundant galatheid crab species in the Beagle Channel (55°S 68°W) off Tierra del Fuego, Argentina. Samples of crabs and the epibenthic community were taken on a monthly basis at two different depth strata (<40 m and >70 m), by means of epibenthic trawling from 1998 to 1999. Stomach contents from 1582 crabs were analysed, out of which only 2% had empty stomachs. The quantity of food in the stomach contents was clearly seasonal and similar at both depths. The organic matter varied throughout the year and between both depths, being significantly higher in summer/spring than in autumn/winter. Munida subrugosa shows two different and simultaneous feeding habits: (1) as a predator M. subrugosa feeds on crustaceans, algae, and polychaetes; and (2) as a deposit feeder M. subrugosa consumes particulate organic matter and organisms associated with the superficial layer of the sediment. The composition of the diet of Munida subrugosa was similar for both years, and independent of depth, sex or season. Munida subrugosa selected crustaceans only in autumn and winter, whereas most food items were found according to their availability in the habitat.


2017 ◽  
Vol 65 (4) ◽  
pp. 1231 ◽  
Author(s):  
Kevin Daniel Alvarez Soraca ◽  
Cesar Enrique Tamaris Turizo ◽  
Cristian José Guzmán Soto

The genera Leptonema and Smicridea belong to the family Hidropsychidae and constitute one of the most important groups in the nutrient dynamics in the tropical aquatic ecosystems, which diversity of microhabitats is exploited by their larvae. However, there is lack of information concerning the detailed and comparative descriptions of mouthparts between these two genera, and their possible relation with their diet. The aim of this paper was to describe the morphology of the mouthparts and the feeding habits of both genera, in the middle basin of the Gaira River (Sierra Nevada de Santa Marta, Colombia). The samples were collected on a monthly basis, with a surber net, between October and December of 2014, and May of 2015. A total of 15 larvae per genus were taken and the Blue Zen Software was used to determine the morphometric measurements of the cephalic pieces. Measurements were taken on photographs obtained from an AxioCam ERc5s camera adapted to a Nikon SMZ 745T stereoscope. To describe the mouthparts a M205A microscope-stereoscope Leica was used. The dietary habits of 15 individuals in total were evaluated by means of the analysis of stomach contents. A discriminant analysis of Hotelling was applied to the morphometric measurements. There were significant differences in head area (HA), head width (HW3), head length (HL2) and left mandible length (LML). In the morphological descriptions were found differences in: head, labrum and submentum. Dietaries profiles were performed to the stomach contents for both genera and the items with highest percentage for Leptonema was MOPG and MOPF with 38 % and 32 %, respectively, and for Smicridea MOPF (38 %) and MOPG (34 %) with significant differences (F = 8.8298, p < 0.05). This study indicated that the evaluated individuals consume a wide variety of resources and the difference of the diet of both genera can be related to the detected morphological differences.


2017 ◽  
Vol 9 (2) ◽  
pp. 9840 ◽  
Author(s):  
Ana Paula Madeira Di Beneditto ◽  
Clara Da Cruz Vidart Badia ◽  
Salvatore Siciliano

Along the north and central coast of Rio de Janeiro State (22025’S–23000’S), southeastern Brazil, the Guiana Dolphin Sotalia guianensis forages on neritic prey, mainly fish.  From the analysis of the dolphin’s stomach contents and the identification of partially digested prey, it was verified that the most frequent prey species were young specimens of Trichiurus lepturus.  Comparing our results with previous studies on the feeding habits of Guiana Dolphin in the same region, we noticed the maintenance of its feeding preferences during more than two decades, indicating little or no change in the use of prey by this top predator. 


Author(s):  
Laura Busin Campos ◽  
Xênia Moreira Lopes ◽  
Ednilson da Silva ◽  
Marcos César de Oliveira Santos

AbstractThis study evaluated the feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil. Stomach contents were collected from a total of 145 dead specimens found incidentally caught by fishing vessels or stranded between 2005 and 2015. Fish otoliths, cephalopod beaks and whole non-digested prey were used for prey species identification. A total of 9337 prey items were identified, including 26 species of teleost fishes and three species of cephalopods. The most important prey families were Sciaenidae among fish and Loliginidae among cephalopods. Franciscana dolphins tended to feed on small fish (mean = 5.25 cm) and cephalopods (mean = 8.57 cm). The index of relative importance (IRI) showed that Pellona harroweri and Doryteuthis plei were the most important prey for both males and females. The PERMANOVA test confirmed that there is no significant difference between the feeding habits of different sexes, but detected a significant difference among seasons. Overall, our results show that franciscana dolphins are predominantly ichthyophagous and non-selective in relation to the type of prey, feeding on pelagic, demersal and pelagic-demersal prey.


2005 ◽  
Vol 65 (3) ◽  
pp. 377-385 ◽  
Author(s):  
P. M. Andrade ◽  
F. M. S. Braga

We compare the classic model of feeding of tropical fish by means of six bimonthly samplings using gillnets of varying mesh sizes that were inspected every twelve hours throughout a forty-eight hour period. The stomachs of the fish caught were classified in three categories according to quantity of food found. The amount of fat in the visceral cavity with respect to the energetic reserve deposition was also studied. The relative frequencies of the different categories of stomach repletion and fat deposition were examined for patterns of feeding seasonality. The stomachs considered full were examined to record diet composition. To assess the relative importance of the different food resources, we applied Feeding Importance Degree (FID), which is a useful index when difficulties exist in determining a common basis for volume, number, or weight of a given food item in different species, a common problem when dealing with fish species having different feeding habits. The fish species whose stomach contents were analyzed using the FID index were Serrasalmus spilopleura (Characidae), L. prolixa (Loricaridae), Schizodon nasutus (Anostomidae), and Pimelodus maculatus (Pimelodidae). Our findings indicate some contrasting elements , in dietary composition in relation to the classic model for tropical rivers. These factors include the importance of aquatic macrophytes, the lack of piscivorous species, and a lesser presence of allochthonous vegetation in the diet of the species studied.


Sign in / Sign up

Export Citation Format

Share Document