Sources of variability and comparability between salmonid stomach contents and isotopic analyses: study design lessons and recommendations

2011 ◽  
Vol 68 (1) ◽  
pp. 137-151 ◽  
Author(s):  
Mark R. Vinson ◽  
Phaedra Budy
Keyword(s):  
Stable Isotope ◽  
Study Design ◽  
Stomach Content ◽  
Stomach Contents ◽  
Stomach Content Analysis ◽  
Diet Overlap ◽  
Target Species ◽  
Relative Information ◽  
Isotopic Analyses ◽  
Diet Analyses

We compared sources of variability and cost in paired stomach content and stable isotope samples from three salmonid species collected in September 2001–2005 and describe the relative information provided by each method in terms of measuring diet overlap and food web study design. Based on diet analyses, diet overlap among brown trout, rainbow trout, and mountain whitefish was high, and we observed little variation in diets among years. In contrast, for sample sizes n ≥ 25, 95% confidence interval (CI) around mean δ15Ν and δ13C for the three target species did not overlap, and species, year, and fish size effects were significantly different, implying that these species likely consumed similar prey but in different proportions. Stable isotope processing costs were US$12 per sample, while stomach content analysis costs averaged US$25.49 ± $2.91 (95% CI) and ranged from US$1.50 for an empty stomach to US$291.50 for a sample with 2330 items. Precision in both δ15Ν and δ13C and mean diet overlap values based on stomach contents increased considerably up to a sample size of n = 10 and plateaued around n = 25, with little further increase in precision.

Food sources of common dolphinfish (Coryphaena hippurus) based on stomach content and stable isotopes analyses

2014 ◽  
Vol 95 (3) ◽  
pp. 579-591 ◽  
Author(s):  
A. Tripp-Valdez ◽  
F. Galván-Magaña ◽  
S. Ortega-García
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Gulf Of California ◽  
Stomach Contents ◽  
Isotopic Analysis ◽  
Stomach Content Analysis ◽  
Food Sources ◽  
Important Prey ◽  
Opportunistic Predator ◽  
Ecological Importance

Dolphinfish (Mahimahi) are a high-demand resource for sport and coastal fisheries, mainly in the Pacific Ocean. Due to their economic and ecological importance, studies of their biology are very important to understand their function in ecosystems. We used stable isotope and stomach content analyses to determine the most important prey of the common dolphinfish, as well as the trophic level of this species in two areas of the southern Gulf of California. Stomach contents of 445 specimens were analysed. Using both techniques, we found that the most important prey for dolphinfish in the southern Gulf of California were three invertebrate species followed by fish. This contrasts with results from other authors who found that this species was mainly piscivorous in other locations. Stomach content analysis indicated differences in prey biomass by area, season and size class. The isotopic analysis did not show significant differences between seasons or sexes. Both stomach contents and stable isotope analyses showed that although this predator consumed a wide prey spectrum, only a few prey items made up the bulk of the diet, which resulted in a low SD in δ15N values and low Levin's index values. We conclude that this fish is an opportunistic predator that may consume a wide prey spectrum, but that it mainly consumes prey that are abundant in the area, such as crustaceans and cephalopods in the Gulf of California.

scholarly journals Diet of Leptobotia elongata revealed by stomach content analysis and inferred from stable isotope signatures

2015 ◽  
Vol 98 (8) ◽  
pp. 1965-1978 ◽  
Author(s):  
L. Li ◽  
Q. Wei Wei ◽  
J. Ming Wu ◽  
H. Zhang ◽  
Y. Liu ◽  
...  
Keyword(s):  
Content Analysis ◽  
Stable Isotope ◽  
Stomach Content ◽  
Stomach Content Analysis ◽  
Stable Isotope Signatures

Niche differentiation of bottlenose dolphin species in South Australia revealed by stable isotopes and stomach contents

2011 ◽  
Vol 38 (4) ◽  
pp. 261 ◽  
Author(s):  
Susan E. Gibbs ◽  
Robert G. Harcourt ◽  
Catherine M. Kemper
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Bottlenose Dolphin ◽  
South Australia ◽  
Stomach Contents ◽  
Primary Source ◽  
Niche Differentiation ◽  
Numerical Abundance ◽  
Significant Difference ◽  
Management And Conservation

Context Animal species with overlapping ranges are common worldwide, but how these species coexist is less obvious. Dolphins are protected in Australia and yet little information is available on their resource use which is essential for successful management and conservation. Aim The aim of this study was to determine the degree of overlap in diet and feeding ecology of the two Tursiops spp. that have overlapping ranges in South Australia. Methods Stomach content (91 Tursiops sp. and 14 T. truncatus) and stable isotope (δ13C, δ15N) analyses (39 Tursiops sp. and 14 T. truncatus) were conducted. Carcasses of dolphins were opportunistically collected between 1974 and 2005. Diet was quantified by frequency of occurrence (FOO) and numerical abundance (NA) of prey. Key results Delta13C from teeth revealed distinct differences in primary source of carbon, corresponding to coastal (Tursiops sp. n = 39,  = –12.24, s.d. = 1.32) and offshore habitats (T. truncatus n = 14,  = –14.21, s.d. = 0.55). Differences in δ15N revealed Tursiops sp. ( = 11.66, s.d. = 0.58) feeds at a lower trophic level than T. truncatus ( = 14.29, s.d. = 0.88). Stomach content analyses for Tursiops sp. corroborated stable isotope results. There was a significant difference between the diets of Tursiops sp. from north Spencer Gulf and south Spencer Gulf (ANOSIM R = 0.249, P = 0.001). Prey were generally demersal in habit with the most important from the cephalopod families Octopodidae, Sepiidae and Loliginidae and fish families Carangidae, Clupeidae, Terapontidae and Apogonidae. For T. truncatus there were insufficient stomach contents for assessment. Conclusions South Australian bottlenose dolphin species exhibit distinct niche differentiation with clear evidence of regional variation in the diet of Tursiops sp. Implications The between and within species diet differentiation demonstrated, highlights the importance of regional management. Such results are internationally significant as coastal and offshore forms of Tursiops spp. occur worldwide.

scholarly journals Seasonal Dynamics of Stomach Contents, Trophic Level, Length-Weight Relationship and Condition Factor of Mystus bleekeri (Day, 1877)

2021 ◽  
Vol 50 (4) ◽  
pp. 907-918
Author(s):  
Sabuj Kanti Mazumder ◽  
Mrityunjoy Kunda ◽  
Mohammed Mahbub Iqbal ◽  
Lipi Rani Basak ◽  
Simon Kumar Das
Keyword(s):  
Trophic Level ◽  
Stomach Content ◽  
Condition Factor ◽  
Stomach Contents ◽  
Stomach Content Analysis ◽  
K Value ◽  
Weight Relationship ◽  
Food Fish ◽  
The Mean ◽  
Asian Catfish

The Asian catfish Mystus bleekeri is a popular food fish along with favored as an ornamental fish in Bangladesh. Till now detailed report on stomach contents, trophic level, length-weight relationship and condition factor of this fish species in the agro-climatic context of Bangladesh is lacking. Hence, the aims of this study were to describe the stomach content, trophic level, length-weight relationship (LWR) and condition factors of Mystus bleekeri collected from Dekhar Haor, Sylhet, Bangladesh from July 2017 to June 2018. A total of 600 specimens ranging from 6.9-24.6 cm total length (TL) and 5.7-72.4 g body weight (BW) was analyzed in this study. Stomach content analysis showed that the fish fed mostly on Mollusca with a frequency of occurrence (fo: 25.36%) and worms (fo: 21.68%), followed by plant matters (fo: 3.32%), Cladocerana (fo: 1.18%), Copepoda (fo: 0.95%), and Teleostei (fo: 0.36%). The estimated mean trophic level (TROPH) ranged from 2.35±0.13 in December to 3.02±0.23 in August, indicating that they are opportunistic feeder. The LWR analysis showed negative allometric growth (b<3) throughout the year. The values of the exponent b in the LWR (W=aLb) vary between 1.474 and 2.490.The mean K value was significantly higher in October indicating the heavier weight and better condition of the fish (P<0.05). The data obtained from this study would be useful to introduce sustainable management of Mystus bleekeri not only in Dekhar Haor but also in other inland waters of Bangladesh.

Are you really what you eat? Stomach content analysis and stable isotope ratios do not uniformly estimate dietary niche characteristics in three marine predators

Oecologia ◽  
2020 ◽  
Vol 192 (4) ◽  
pp. 1111-1126 ◽  
Author(s):  
Julia C. Petta ◽  
Oliver N. Shipley ◽  
Sabine P. Wintner ◽  
Geremy Cliff ◽  
Matt L. Dicken ◽  
...  
Keyword(s):  
Content Analysis ◽  
Stable Isotope ◽  
Stomach Content ◽  
Isotope Ratios ◽  
Stomach Content Analysis ◽  
Stable Isotope Ratios ◽  
Marine Predators ◽  
Dietary Niche

Diet and isotopic niche of eastern sand darter (Ammocrypta pellucida) near the northern edge of its range: a test of niche specificity

2019 ◽  
Vol 97 (9) ◽  
pp. 763-772 ◽  
Author(s):  
Jacob Burbank ◽  
Mary Finch ◽  
D. Andrew R. Drake ◽  
Michael Power
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Stomach Content ◽  
Isotope Analysis ◽  
Resource Limitation ◽  
Niche Overlap ◽  
Stomach Content Analysis ◽  
Trophic Niche ◽  
Isotopic Niche ◽  
Population Declines

Niche specificity can predispose species to population declines during periods of resource limitation, yet trophic niche specificity is poorly known for many small-bodied freshwater fishes. Applying a two-tiered approach involving stomach content and stable isotope analyses, we examined the diet and trophic niche of the threatened eastern sand darter (Ammocrypta pellucida (Putnam, 1863)) and co-occurring fishes in the Thames River, Ontario, Canada. As with previous studies, stomach content analysis revealed that eastern sand darter consumed a variety of benthic organisms including Chironomidae, Cladocera, Ostracoda, Oligochaeta, and Ephemeroptera; however, proportional contributions of prey groups differed based on stable isotope analysis, highlighting the potential for seasonal variation in prey consumption. Despite evidence of a generalist strategy, stable isotope analysis indicated eastern sand darter exhibited a relatively narrow trophic niche relative to co-occurring fishes. Trophic niche overlap was relatively minor between eastern sand darter and drift-feeding fishes (spotfin shiner (Cyprinella spiloptera (Cope, 1867)), emerald shiner (Notropis atherinoides Rafinesque, 1818), and buffalo sp. (genus Ictiobus Rafinesque, 1820)), but was more evident between eastern sand darter and benthic and benthopelagic fishes (johnny darter (Etheostoma nigrum Rafinesque, 1820) and blackside darter (Percina maculata (Girard, 1859))), indicating that competition with these species may be more likely during periods of prey scarcity.

scholarly journals Feeding habits and population aspects of the spotted goatfish, Pseudupeneus maculatus (Perciformes: Mullidae), on the continental shelf of northeast Brazil

2020 ◽  
Vol 84 (2) ◽  
Author(s):  
Andrey Soares ◽  
Alex Souza Lira ◽  
Júlio Guazzelli Gonzalez ◽  
Leandro Nolé Eduardo ◽  
Flávia Lucena-Frédou ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Continental Shelf ◽  
Trophic Position ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Distribution Patterns ◽  
Isotope Ratios ◽  
Stomach Content Analysis ◽  
Stable Isotope Ratios ◽  
Weight Percentage

This study provides information about the feeding habits, population aspects and spatial distribution of the spot­ted goatfish, Pseudupeneus maculatus, along the coast of the tropical Brazilian continental shelf. Distribution patterns are described using length frequencies and catch rates. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N), along with stomach contents, were analysed to determine the diet of the spotted goatfish. Multivariate analysis and numerical indicators of the diet, such as numerical frequency, frequency of occurrence and weight percentage, were computed to evaluate the diet composition. The mean trophic position was defined using both stable isotope ratios and stomach content analysis. The length at first maturity for the species was determined as 13.7 cm. A slight pattern in size distribution was observed, with mean size increasing with depth along the shelf. The diet was mainly composed of crustaceans, teleosts and Polychaeta. No clear dietary difference was found between habitat types, water depth or latitude. Both trophic positions estimated by stable isotopes and stomach contents analysis ranged between levels 3 and 4. P. Maculatus was found to be feeding on many rare and infrequent prey items, classifying it as a generalist zoobenthivorous predator, probably due to its efficient search strategy.

scholarly journals Offshore wind farms and the attraction–production hypothesis: insights from a combination of stomach content and stable isotope analyses

Hydrobiologia ◽  
2021 ◽  
Author(s):  
Ninon Mavraki ◽  
Steven Degraer ◽  
Jan Vanaverbeke
Keyword(s):  
Stable Isotope ◽  
Stomach Content ◽  
Wind Farms ◽  
Offshore Wind ◽  
Artificial Reefs ◽  
Dietary Composition ◽  
Trachurus Trachurus ◽  
Offshore Wind Farms ◽  
Scomber Scombrus ◽  
Isotope Analyses

AbstractOffshore wind farms (OWFs) act as artificial reefs, attracting high abundances of fish, which could potentially increase their local production. This study investigates the feeding ecology of fish species that abundantly occur at artificial habitats, such as OWFs, by examining the short- and the long-term dietary composition of five species: the benthopelagic Gadus morhua and Trisopterus luscus, the pelagic Scomber scombrus and Trachurus trachurus, and the benthic Myoxocephalus scorpioides. We conducted combined stomach content and stable isotope analyses to examine the short- and the time-integrated dietary composition, respectively. Our results indicated that benthopelagic and benthic species utilize artificial reefs, such as OWFs, as feeding grounds for a prolonged period, since both analyses indicated that they exploit fouling organisms occurring exclusively on artificial hard substrates. Trachurus trachurus only occasionally uses artificial reefs as oases of highly abundant resources. Scomber scombrus does not feed on fouling fauna and therefore its augmented presence in OWFs is probably related to reasons other than the enhanced food availability. The long-termed feeding preferences of benthic and benthopelagic species contribute to the hypothesis that the artificial reefs of OWFs could potentially increase the fish production in the area. However, this was not supported for the pelagic species.

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