Zeros as a result in diet studies, is this really bad? Rhinoptera steindachneri as a case study

2019 ◽  
Vol 99 (7) ◽  
pp. 1661-1666 ◽  
Author(s):  
N. R. Ehemann ◽  
L. A. Abitia-Cardenas ◽  
A. F. Navia ◽  
P. A. Mejía-Falla ◽  
V. H. Cruz-Escalona
Keyword(s):  
Eating Habits ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Geographic Location ◽  
La Paz ◽  
Important Species ◽  
Mexican Pacific ◽  
Important Prey ◽  
Commercially Important ◽  
Prey Handling

AbstractRhinoptera steindachneri is a commercially important, medium-sized, pelagic migratory batoid fish with benthic feeding habits. It has been considered a specialized predator that feeds on molluscs as well as benthic ophiurids and arthropods off the Mexican Pacific coast. Most biological aspects of this species in La Paz Bay are unknown, despite its being a commercially important species of conservation interest. Therefore, the aim of this study was to characterize the feeding habits of R. steindachneri based on specimens caught in artisanal fisheries. The stomach contents of 310 specimens (146 females and 164 males) were analysed, all captured from 2013 to 2015. The vacuity index was 97.1%, and the most important prey species were Mysidium spp. and Cylichna spp. Because of the high frequency of empty stomachs recorded, it was not possible to describe with precision the general diet of the species. Three hypotheses were developed to try to explain why this characteristic occurred in this species, ranging from eating habits to physiology and prey digestion and geographic location of the study. However, considering the mechanical process of prey handling of R. steindachneri, several hypotheses were formulated, with the hour of capture, chemical processes and physiology and prey digestion being the most probable to explain this high vacuity index reported in this study.

Trophic spectrum of the sailfish Istiophorus platypterus caught off Acapulco in the southern Mexican Pacific

2012 ◽  
Vol 93 (4) ◽  
pp. 1097-1104 ◽  
Author(s):  
Sandra Berenice Hernández-Aguilar ◽  
Leonardo Andrés Abitia-Cárdenas ◽  
Xchel Gabriel Moreno-Sánchez ◽  
Marcial Arellano-Martínez ◽  
Eduardo González-Rodríguez
Keyword(s):  
Prey Species ◽  
Feeding Habits ◽  
Coastal Region ◽  
Important Species ◽  
Mexican Pacific ◽  
Istiophorus Platypterus ◽  
Important Prey ◽  
Males And Females ◽  
Index Of Relative Importance ◽  
Size Interval

The sailfish Istiophorus platypterus is one of the most common billfish species in the Mexican Pacific. Information about its feeding habits in the coastal region of Acapulco, Guerrero is extremely limited. In the present study we quantified the diet of sailfish, based on captures made from March 2008 to December 2009 by the sport fishing fleet of Acapulco. We analysed a total of 561 stomachs, of which 254 contained food (45%). The size interval of examined specimens was between 101 and 212 cm postorbital length and between 15 and 47 kg total weight. In general, teleosts were the most important prey, followed by cephalopods. According to index of relative importance, the most important species in the diet were the fish Auxis thazard (63.04%) and Fistularia commersonii (6.62%), followed by the cephalopod Octopus spp. (4.58%). There were no significant differences in the diet by sex (males and females), sexual maturity (immature and mature), or by season (warm and cold seasons). In all cases the most important prey species was A. thazard. We conclude that the sailfish I. platypterus off Acapulco behaves as a specialist predator because, despite the consumption of a high number of prey items, it feeds preferentially on a reduced number of prey species that form schools, and are available and abundant in the ocean.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Stable Isotope ◽  
Isotope Composition ◽  
Feeding Habits ◽  
Important Species ◽  
Isotopic Signatures ◽  
Ecological Changes ◽  
Varied Diet ◽  
Commercially Important ◽  
C And N

Abstract.—Spiny dogfish <em>Squalus acanthias </em>are an abundant and commercially important species of fish off both the Atlantic and Pacific coasts of North America. They are opportunistic feeders and have a varied diet that can include many fish species, especially small forage fish such as herring, capelin, and sand lance as well as crustaceans, worms, euphausiids, gelatinous zooplankton, and cephalopods. The purpose of our present study is to investigate the utility of the second dorsal spine in providing multiyear information on the feeding habits of dogfish using stable isotope (C and N) analysis. The outer dentine and enamel layers of a spine from three dogfish (caught off the coast of British Columbia) were analyzed to obtain their stable nitrogen and carbon isotope composition (δ<sup>15</sup>N and δ<sup>13</sup>C, respectively). Each sample had annuli from multiple years, allowing possible seasonal migrations to be averaged over samples. The δ<sup>15</sup>N ranged from a low of 11.6‰ to a high of 14.9‰ over the three spines and δ<sup>13</sup>C ranged from –11.5‰ to –18.4‰. The variable isotopic signatures along the spine indicate that the method may be used to assess ecological changes. Stable isotope measurements of dogfish spines could be a valuable means of determining long-term changes in habitat usage and feeding ecology.

scholarly journals Feeding habits of the franciscana dolphin (Pontoporia blainvillei) in south-eastern Brazil

2020 ◽  
Vol 100 (2) ◽  
pp. 301-313
Author(s):  
Laura Busin Campos ◽  
Xênia Moreira Lopes ◽  
Ednilson da Silva ◽  
Marcos César de Oliveira Santos
Keyword(s):  
Feeding Habits ◽  
Stomach Contents ◽  
Small Fish ◽  
South Eastern ◽  
Important Prey ◽  
Fishing Vessels ◽  
Eastern Brazil ◽  
Significant Difference ◽  
Pontoporia Blainvillei ◽  
Franciscana Dolphin

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.

Feeding of tub gurnard Chelidonichthys lucerna (Scorpaeniformes: Triglidae) in the north-east Mediterranean

2011 ◽  
Vol 92 (3) ◽  
pp. 605-612 ◽  
Author(s):  
Marco Stagioni ◽  
Stefano Montanini ◽  
Maria Vallisneri
Keyword(s):  
Diet Composition ◽  
Foraging Behaviour ◽  
Adriatic Sea ◽  
Feeding Habits ◽  
Feeding Activity ◽  
Stomach Contents ◽  
East Mediterranean ◽  
North East ◽  
The North ◽  
Important Prey

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.

scholarly journals Feeding habits of some demersal fish on the Charleston Bump off the southeastern United States

2010 ◽  
Vol 68 (2) ◽  
pp. 390-398 ◽  
Author(s):  
Sarah F. Goldman ◽  
George R. Sedberry
Keyword(s):  
United States ◽  
Feeding Habits ◽  
Southeastern United States ◽  
Stomach Contents ◽  
Demersal Fish ◽  
Trophic Relationships ◽  
Food Sources ◽  
Mesopelagic Fish ◽  
Important Species ◽  
Charleston Bump

Abstract Goldman, S. F. and Sedberry, G. R. 2011. Feeding habits of some demersal fish on the Charleston Bump off the southeastern United States. – ICES Journal of Marine Science, 68: 390–398. The feeding habits of several demersal fish on the upper continental slope were investigated to determine the trophic relationships of these ecologically dominant and commercially important species, and to determine food sources for slope fish off the southeastern United States. Stomach contents were examined from 534 fish, including wreckfish (Polyprion americanus), barrelfish (Hyperoglyphe perciformis), and red bream (Beryx decadactylus). Fish fed on 46 prey taxa, and there were dietary differences among predators. Wreckfish predominantly consumed teleost fish and squid; barrelfish had a diet dominated by pelagic tunicates and some mesopelagic fish and squid; red bream consumed mainly fish, squid, and crustaceans. Seasonal shifts in diet were observed in all three species. Many of the prey items encountered were vertically migrating organisms, which are a critical link between surface waters and the slope ecosystem.

Feeding ecology of little tunny Euthynnus alletteratus in the central Mediterranean Sea

2007 ◽  
Vol 87 (4) ◽  
pp. 999-1005 ◽  
Author(s):  
Manuela Falautano ◽  
Luca Castriota ◽  
Maria Grazia Finoia ◽  
Franco Andaloro
Keyword(s):  
Mediterranean Sea ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Prey Abundance ◽  
Central Mediterranean ◽  
Size Classes ◽  
Larval Stages ◽  
Important Prey ◽  
Predator Size ◽  
Central Mediterranean Sea

The feeding habits of Euthynnus alletteratus and its variations compared to predator size in the central Mediterranean Sea were investigated. The stomach contents of 187 specimens were analysed, ranging from 26.8 to 50.3 cm total length, caught by authorized experimental drift-nets. The difference in food items found in the stomachs was evaluated by occurrence of prey frequency, prey weight, and prey abundance; these criteria were used to calculate an index of relative importance. Fish were the dominant food detected according to all numerical indicators examined and were mainly represented by Maurolicus muelleri and larval stages of teleosts. Hyperiid amphipods, dominated by Anchylomera blossevillei and Phrosina semilunata, were well represented in terms of frequency of occurrence. Variations in the diet composition compared to fish size were observed. Comparative analysis performed on prey abundance highlighted a trend of increasing predator size-classes among prey items. The specimens of the smallest sizes ate mainly adult clupeiforms and larvae or other juvenile teleosts. As fish grew, there were increased amounts of adult teleosts, crustaceans (hyperiids and isopods) and cephalopods. Maurolicus muelleri was the most important prey for the largest specimens analysed. Significant differences among size-classes, both in prey abundance and in prey weight, were confirmed by non-parametric multivariate analysis of variance (NP-MANOVA).

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

2007 ◽  
Vol 87 (4) ◽  
pp. 1007-1012 ◽  
Author(s):  
E. Mostarda ◽  
D. Campo ◽  
L. Castriota ◽  
V. Esposito ◽  
M.P. Scarabello ◽  
...  
Keyword(s):  
Diet Composition ◽  
Fish Larvae ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Hierarchical Cluster ◽  
Eastern Coast ◽  
Tyrrhenian Sea ◽  
Monthly Basis ◽  
The North ◽  
Important Prey

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.

scholarly journals THE FEEDING HABITS OF JUVENILE SCALLOPED HAMMERHEAD SHARKS (SPHYRNA LEWINI) CAUGHT IN THE GULF OF NICOYA, COSTA RICA

2016 ◽  
Vol 39 (2) ◽  
Author(s):  
Ilena Zanella Cesarotto ◽  
Andrés López Garro ◽  
Randall Arauz Vargas
Keyword(s):  
Teleost Fish ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Geographic Location ◽  
Niche Separation ◽  
Sphyrna Lewini ◽  
Scalloped Hammerhead ◽  
Importance Index ◽  
Hammerhead Sharks ◽  
Gulf Of Nicoya

Sharks present strong intraspecific changes in feeding habits, which may vary according to size, geographic location and season. This study analyzed the stomach contents of 52 juvenile scalloped hammerhead sharks (25 females and 27 males) caught by artisanal vessels in the Gulf of Nicoya. Regarding the organisms found in the stomachs, 41.07 % were teleost fish, 30.36 % mollusks and 28.57 % crustaceans. Mollusks presented  the  highest  Relative Importance Index  (RII) (43.05  %), followed by teleost fish (41.37 %) and crustaceans (15.58 %). Squids (Loliginidae) were the items with the greatest RII (32.57 %). By means of the Pianka index, a relatively low overlap between sexes was identified, suggesting a  spatial sexual segregation and, in consequence, an ecological niche separation between male and female hammerhead sharks.

Examination of the stomach contents from a Mediterranean sperm whale found south of Crete, Greece

2003 ◽  
Vol 83 (3) ◽  
pp. 667-670 ◽  
Author(s):  
Stephen M. Roberts
Keyword(s):  
Eastern Mediterranean ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Premature Death ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Rigid Plastic ◽  
Important Species ◽  
Normal Feeding ◽  
Insight Into

The stomach contents from a male sperm whale, Physeter macrocephalus, first located floating a short distance off the south coast of Crete were examined. The remains within the stomach consisted almost exclusively of cephalopod mandibles, or beaks, though other material was found including a piece of rigid plastic mesh. Of the beaks found, 1714 were upper beaks and 2178 were lower beaks, that were used to identify the species. A total of seven species was identified, all of which have been previously recorded in the eastern Mediterranean though are rarely caught by man. Of these Histioteuthis bonnellii was found to be the most important species in terms of both weight and numbers. Although it must be borne in mind that the whale may not have followed its normal feeding habits prior to its premature death, an important insight into its prey items can be revealed. This is the first documented account of the stomach contents of a sperm whale from the Mediterranean, and helps to complete a global record of sperm whale diets.

Seasonal changes in depth distribution of salmon sharks (Lamna ditropis) in Alaskan waters: implications for foraging ecology

2011 ◽  
Vol 68 (11) ◽  
pp. 1905-1921 ◽  
Author(s):  
Aaron B. Carlisle ◽  
Christopher R. Perle ◽  
Kenneth J. Goldman ◽  
Barbara A. Block
Keyword(s):  
Seasonal Changes ◽  
Depth Distribution ◽  
Prey Species ◽  
Foraging Ecology ◽  
Gulf Of Alaska ◽  
Apex Predator ◽  
Important Species ◽  
Important Prey ◽  
Commercially Important ◽  
High Degree

The salmon shark, Lamna ditropis, is an endothermic, apex predator in the productive waters of the Gulf of Alaska (GOA). To understand their role in these productive habitats and to identify and better understand their interactions with commercially important species and fisheries, detailed information regarding the distribution of the salmon shark is required. Archival data records from eight recovered pop-up archival transmitting (PAT) tags were analyzed to examine the geographic and vertical distribution of female salmon sharks and elucidate how their distribution changes in relation to the biotic and abiotic environment. Tagged sharks used the neritic habitats of the GOA for the duration of the PAT deployments. Sharks exhibited a diel periodicity in their dive behavior. Salmon sharks exhibited three different patterns of depth distribution (behavioral modes) that occurred during distinct oceanographic seasons, likely reflecting changes in their foraging ecology in response to seasonal changes in the distribution and availability of important prey. The distribution of salmon sharks in the GOA appears to follow consistent patterns and has a high degree of geographical and vertical overlap with commercially important prey species. This information increases our understanding of interactions between salmon sharks and commercial fisheries and may assist in fostering responsible management for this species.

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