Evaluating fish diet analysis methods by individual-based modelling

2012 ◽  
Vol 69 (7) ◽  
pp. 1184-1201 ◽  
Author(s):  
Ida Ahlbeck ◽  
Sture Hansson ◽  
Olle Hjerne
Keyword(s):  
Diet Composition ◽  
Prey Size ◽  
Diet Analysis ◽  
Fish Diet ◽  
Relative Importance ◽  
Fish Prey ◽  
Analysis Methods ◽  
Composite Indices ◽  
Index Of Relative Importance ◽  
Better Than

Knowledge of diet compositions is important in ecological research. There are many methods available and numerous aspects of diet composition. Here we used modelling to evaluate how well different diet analysis methods describe the “true” diet of fish, expressed in mass percentages. The methods studied were both basic methods (frequency of occurrence, dominance, numeric, mass, points) and composite indices (Index of Relative Importance, Comparative Feeding Index). Analyses were based on both averaged stomach content of individual fish and on pooled content from several fish. Prey preference, prey size, and evacuation rate influenced the performance of the diet analysis methods. The basic methods performed better than composite indices. Mass and points methods produced diet compositions most similar to the true diet and were also most robust, indicating that these methods should be used to describe energetic–nutritional sources of fish.

Prey selection by harbour seals, Phoca vitulina, in relation to variations in prey abundance

1997 ◽  
Vol 75 (9) ◽  
pp. 1508-1518 ◽  
Author(s):  
Dominic J. Tollit ◽  
Paul M. Thompson ◽  
Simon P. R. Greenstreet
Keyword(s):  
Diet Composition ◽  
Prey Size ◽  
Prey Selection ◽  
Phoca Vitulina ◽  
Correction Factors ◽  
Fish Prey ◽  
Size Selection ◽  
Harbour Seals ◽  
Moray Firth ◽  
Time Periods

This study compared the composition of the diet of harbour seals (Phoca vitulina) feeding in the Moray Firth, Scotland, with the abundance of their fish prey estimated from dedicated fishery surveys in January 1992 and 1994 and June 1992. Prey-size selection was also examined in these three time periods and in January 1991. In each period, the most abundant fish species contributed most to the diet. However, the relative abundances of the remaining species in the sea showed little similarity to their contribution to the seals' diet. Diet composition was almost totally dominated by either pelagic species or species dwelling on or strongly associated with the seabed, depending upon the relative abundance of pelagic schooling prey. Most fish consumed were 10–16 cm in length, although larger cod and herring were taken. With the exception of cod, the extent of size selection was dependent upon the use of correction factors that accounted for otolith erosion due to digestion.

scholarly journals The use of premaxillary bones of six fish species in giant otter (Pteronura brasiliensis) diet analysis

2015 ◽  
Vol 10 (2) ◽  
pp. 131-142
Author(s):  
Maria del Pilar Becerra Cardona ◽  
Heiddy Asunción Mallea Cardenas ◽  
Paul André Van Damme
Keyword(s):  
Fish Species ◽  
Standard Length ◽  
Prey Size ◽  
Morphological Characteristics ◽  
Diet Analysis ◽  
Regression Equations ◽  
Fish Prey ◽  
Important Prey ◽  
Bolivian Amazon ◽  
Pteronura Brasiliensis

The premaxillary bones of fish are considered key bones due to their highly differentiated features, allowing the identification to species level. When these bones are present in the latrines of giant otter (Pteronura brasiliensis), they can be used to identify fish species and estimate the size of prey consumed. We briefly describe the differentiable morphological characteristics of premaxillary bones,useful for the successful identification of six fish species which are important prey for giant otter in the Paraguá river (Bolivian Amazon): Hoplias malabaricus (family Erithrynidae), Serrasalmus rhombeus, Pygocentrus nattereri (family Characidae), Chaetobranchus flavescens, Satanoperca pappaterra and Astronotus crassipinnis (family Cichlidae). We also present the linear regression equations which can be used to estimate the standard length ofthese fish species based on their bone measurements. Overall, 19 latrine samples were analyzed, which contained 109 premaxillarybones of these six species. Of the bones collected, 53% allowed successful estimation of the standard length of the fish consumed. The use of premaxillary bones in diet studies has a high potential as it permits the identification and estimation of prey size for the majority of species consumed. This method is important for studying the size of the giant otter’s fish prey.

Swordfish Xiphias gladius diet in the Florida Straits

2020 ◽  
Vol 96 (4) ◽  
pp. 695-706
Author(s):  
Amy M Heemsoth ◽  
Amy C Hirons ◽  
Caroline M Collatos ◽  
David W Kerstetter
Keyword(s):  
Diet Composition ◽  
Stomach Contents ◽  
Relative Importance ◽  
Crustacean Species ◽  
Index Of Relative Importance ◽  
Xiphias Gladius ◽  
Florida Straits ◽  
Prey Length ◽  
Positive Significant Correlation

Swordfish Xiphias gladius inhabit the Florida Straits year-round and provide a significant role in the food web as top-level predators. However, little is known about the diet composition and thus ecological role of swordfish in Florida. This study investigated swordfish diet by analyzing stomach contents of 131 swordfish in the Florida Straits from April 2007 to December 2008. Identifiable species included 13 teleost species, 3 cephalopod species, and 1 crustacean species. Cephalopods dominated the swordfish diet by weight (72.4%) and number (69.9%), and ranked highest in importance in the diet by the index of relative importance (IRI; 81.5%). Teleosts occurred the most (99.1%) but represented the second highest importance in diet by weight (25.2%), number (26.3%), and IRI (17.6%). Illex sp. was the prey with the greatest dietary importance, followed by unidentifiable ommastrephid squids. Stomach fullness index values ranged from 0 (empty) to 8.98 (mean = 0.37). A positive significant correlation between swordfish length and prey length was found (r2 = 0.104, P = 0.037), and no significant correlations were found between swordfish weight and prey weight (r2 = –0.075, P = 0.065). This is the first study to report a comprehensive diet of swordfish inhabiting waters in the Florida Straits region and suggests swordfish may be opportunistic feeders, altering their diet when abundance or presence of prey changes.

Diet of Antarctic toothfish (Dissostichus mawsoni) from the continental slope and oceanic features of the Ross Sea region, Antarctica

2014 ◽  
Vol 26 (5) ◽  
pp. 502-512 ◽  
Author(s):  
Darren W. Stevens ◽  
Matthew R. Dunn ◽  
Matthew H. Pinkerton ◽  
Jeff S. Forman
Keyword(s):  
Continental Slope ◽  
Diet Composition ◽  
Ross Sea ◽  
Fish Diet ◽  
Antarctic Toothfish ◽  
Fish Prey ◽  
Dissostichus Mawsoni ◽  
Antimora Rostrata ◽  
Benthic Fishes ◽  
Important Fish

AbstractThe diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined during 2003, 2005 and 2010. The diet of sub-adult toothfish was similar to adult toothfish, comprising mainly benthic fishes and cephalopods. Sub-adult toothfish ate a greater variety of smaller prey than adults, including smaller fish and prawns. Grenadiers (Macrourus spp.) were the most important fish and overall prey species. On the continental slope, icefish (Channichthyidae) and eel cods (Muraenolepididae) were also important fish prey, while Psychroteuthis glacialis was the most important cephalopod prey. On oceanic features, toothfish fed mainly on Macrourus spp. but also fed on Antimora rostrata, cephalopods and the occasional mesopelagic to epipelagic fish. Diet varied significantly with toothfish size and location on northern parts of the Mawson and Iselin banks of the Ross Sea continental slope. There was no significant temporal change in diet composition.

scholarly journals Diet and feeding habits of Saurida tumbil (Bloch, 1795) from northern Kerala, South-west coast of India

2016 ◽  
Vol 63 (4) ◽  
Author(s):  
P. P. Manojkumar ◽  
P. P. Pavithran
Keyword(s):  
West Coast ◽  
Prey Size ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Relative Importance ◽  
West Coast Of India ◽  
South West ◽  
South West Coast ◽  
Index Of Relative Importance ◽  
Maximum Similarity

Composition of the diet of greater lizardfish Saurida tumbil (Bloch, 1795), caught from northern Kerala, south-west coast of India was studied and described. The stomachs of 1981 specimens were collected between January, 2012 and June, 2014. Analysis of stomach contents based on index of relative importance (IRI) revealed that this species is exclusively piscivorous. Contrary to other benthic predators of the study area, it mainly feeds on pelagic and demersal fishes(IRI = 63.2), molluscs (IRI = 17.86), crustaceans (IRI = 18.33) and other miscellaneous items (IRI = 2.54). The diet of S. tumbil were found to be related to the seasonal availability of resources, occurrence of juveniles of certain species and on the migration of fishes from nearby places to the study area. Significant changes in prey items were observed between predator length groups, but a positive, significant relationship was recorded between prey size and predator size (p<0.05). Statistical analysis indicated a uniform representation of different diets in the stomach. Maximum similarity in diet between different food items was found in April and November.

Explaining diet composition of North Sea cod (Gadus morhua): prey size preference vs. prey availability

2003 ◽  
Vol 60 (2) ◽  
pp. 140-150 ◽  
Author(s):  
Jens Floeter ◽  
Axel Temming
Keyword(s):  
North Sea ◽  
Diet Composition ◽  
Gadus Morhua ◽  
Prey Size ◽  
Prey Availability ◽  
Weight Ratio ◽  
Fish Prey ◽  
Gear Efficiency ◽  
Species Specific ◽  
Size Preference

The nature and significance of size preference for fish prey in the diet selection of North Sea cod (Gadus morhua L.) was analysed. The analysis combined information on size-specific abundance derived from bottom trawl surveys with prey size frequencies in cod stomachs from the International North Sea Stomach Database. To estimate the abundance of all potential fish prey in the sea, a length-based number spectrum was calculated, corrected for gear efficiency by the application of a species-specific correction factor, and weighted by local predator abundance to take the spatial–temporal overlap between cod and its prey into consideration. A prey size preference model for cod feeding on fish is presented. Results showed that the preferred predator-to-prey weight ratio is an exponentially increasing function of predator size and an exponentially decreasing function of the slope of the number spectrum. More than 75% of fish found in the stomachs of North Sea cod originated from the least preferred quartile of the prey size range, indicating that prey abundance is the main determinant of the diet composition.

scholarly journals Diet and Feeding Habits of the Javelin Grunt Pomadasys kaakan (Cuvier, 1830) in Pabean Bay West Java

2018 ◽  
Vol 20 (1) ◽  
pp. 31
Author(s):  
Chilmia Ayu Annisa ◽  
M Fadjar Raharjo ◽  
Ahmad Zahid ◽  
Charles P.H Simanjuntak ◽  
Aries Asriansyah ◽  
...  
Keyword(s):  
Niche Breadth ◽  
Feeding Habits ◽  
Feeding Habit ◽  
Fish Diet ◽  
Relative Importance ◽  
Importance Value ◽  
West Java ◽  
Size Groups ◽  
Index Of Relative Importance

The Pabean Bay is an estuary area that inhabited by many fish species such as javelin grunt (Pomadasys kaakan Cuvier, 1830). The purposes of this study were to identify food item and determine the feeding habit of the javelin grunt in The Pabean Bay, West Java. Fishes were collected monthly from June to December 2016 using gill nets and trap nets. Observation food is in vitro by conducting an examination of the stomach and the intestines of an example and refer on the books of the identification by Carpenter and Niem. Analysis of fish diet includes index of relative importance, niche breadth, and niche overlap. Fishes were grouped into three groups based on the size length. The result showed that the javelin grunt was crustacivore. Generally, the diet of javelin grunt consists of Acetes sp., Penaeus sp., Portunus sp., Clupeid, Ambassid, Sciaenid, Gobiid, Sillaginid, and unidentified organisms. Penaeus sp. was the main food and could be found on each size of group in monthly observation. The proportion of index of relative importance value was changed in regard of length size groups of A (41-85 mm: 12.105), B (86-130 mm: 13.804), and C (131-175 mm: 7.561). The niche breadth of javelin fish was higher in the larger ones and a high diet overlap among size groups was found. According to prey item and feeding habit, the javelin grunt can be classified as benthic crustacean feeder.

scholarly journals Diet Composition and Trophic Level of Greater Forkbeard Phycis blennoides (Gadiform: Phycidae) from the Algerian Coast

2018 ◽  
Vol 76 (4) ◽  
pp. 135-144
Author(s):  
Zakia Alioua ◽  
Soumia Amira ◽  
Farid Derbal ◽  
Mounira Rachedi ◽  
Lamia Bahbah ◽  
...  
Keyword(s):  
Trophic Level ◽  
Diet Composition ◽  
Feeding Habits ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Relative Importance ◽  
Diverse Range ◽  
Qualitative And Quantitative ◽  
Algerian Coast ◽  
Index Of Relative Importance

Abstract The diet of the greater forkbeard Phycis blennoides (Brünnich, 1768) of the Algerian coast was studied between December 2013 and June 2015, providing information on its ecology for a better understanding of the feeding strategy. A total of 956 individuals, whose total length (TL) varied between 9.7 and 54.5 cm and weight (W) between 2.80 and 1334.11 g, were examined. The index of relative importance (%IRI), combining the three main descriptors of the presence of different ingested prey (%F, %N, %W), was used to characterize the relative importance of different food taxa. Qualitative and quantitative variations in diet were studied according to sex, size and seasons. The average annual digestive vacuity index (%V) was 5.51. It did not vary between seasons (x2cal = 5.43, x2th = 7.82, α = 5%) and size (x2cal = 2.08, x2th = 5.99, α = 5%), but was different between male (%V = 4.94) and female (%V= 12.78). Qualitative analysis of stomach contents reveals a fairly diverse range of predation with 1342 preys counted for a total weight of 462.84 g, which corresponds to an average number (AN) and weight (AW) of 3.03 and 1.04 g, respectively. This species feeds on benthic preys, composed mainly of natantia crustaceans (%IRI = 44.84) and teleost fish (%IRI = 2.61) with intraspecific preys (%IRI = 6.15). This cannibalism was frequent in specimens with a TL that exceeds 20 cm; it was even more frequent in females as well as in winter. Significant differences in feeding habits of P. blennoides occurred according to sex, fish size and between seasons. The trophic level (TROPH) was high (3.66 < TROPH < 3.97), corresponding to carnivorous character.

The role of fish in the diet of swordfish (Xiphias gladius) in the Strait of Gibraltar

2017 ◽  
Vol 98 (4) ◽  
pp. 895-907 ◽  
Author(s):  
Noureddine Abid ◽  
Amin Laglaoui ◽  
Abdelhay Arakrak ◽  
Mohammed Bakkali
Keyword(s):  
Diet Composition ◽  
Prey Size ◽  
The Body ◽  
Trachurus Trachurus ◽  
Strait Of Gibraltar ◽  
Important Prey ◽  
Index Of Relative Importance ◽  
Xiphias Gladius ◽  
Diet Preferences

To study the diet of the swordfish (Xiphias gladius) in the Strait of Gibraltar, a total of 176 stomachs were examined from the Moroccan artisanal fishery targeting this species, from April to September 2015. The frequency of occurrence (FO), percentage in number and in weight of prey as well as the per cent index of relative importance of prey (%IRI) were calculated to assess the diet preferences of swordfish in relation to its body size, sex and month. Our findings confirm the opportunistic feeding behaviour of swordfish. The prey items consist primarily of fish (54.6% in number and 82.7% in weight), followed by cephalopod (43.36% in number and 17.25% in weight). The Atlantic horse mackerel (Trachurus trachurus) and the southern shortfin squid (Illex coindetii) are the most important prey, with a % IRI of 47.54 and 35.04%, respectively. The results revealed that there are no significant differences in the diet preferences among sexes and size classes. However, diet composition varied significantly among months. A significant correlation was found between the body length of predator and prey size. The remarkable decrease in the fullness index (fi) from June to August suggests that swordfish were in a spawning condition, with reduced feeding.

scholarly journals Diet composition and feeding habits of the eyespot skate, Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae), off Uruguay and northern Argentina

2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Santiago A. Barbini ◽  
Luis O. Lucifora
Keyword(s):  
Body Size ◽  
Diet Composition ◽  
Prey Size ◽  
Prey Availability ◽  
Feeding Habits ◽  
Warm Season ◽  
Cold Season ◽  
The North ◽  
Multiple Hypothesis ◽  
Modelling Approach

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.

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