Stomach Flushing: Effectiveness and Influence on Survival and Condition of Juvenile Salmonids

1978 ◽  
Vol 35 (10) ◽  
pp. 1359-1363 ◽  
Author(s):  
William R. Meehan ◽  
Richard A. Miller
Keyword(s):  
Coho Salmon ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Wild Fish ◽  
Key Words Stomach ◽  
Hatchery Fish ◽  
Juvenile Salmonids ◽  
Significant Difference ◽  
Change In Mean

Hydraulic stomach flushing was an effective method to analyze relative food consumption and feeding habits of young salmonids. Coho salmon (Oncorhynchus kisutch) stomachs were most effectively flushed — 99% of invertebrate organisms (96% of weight of stomach contents); 92% of organisms (83% of weight) were flushed from cutthroat trout (Salmo clarki) stomachs, 90% of organisms (77% of weight) were flushed from rainbow trout (S. gairdneri) stomachs. Stomach flushing did not affect survival of juvenile coho salmon. A significant difference in change in mean condition factor between wild and hatchery fish was found after 30 d (greater change in wild fish), and a significant change was observed between the mean condition factors of control and treated hatchery fish. No difference was found between control and treated wild fish. Key words: stomach flushing, juvenile salmonids, survival, condition, food habits

Effects of Early Rearing Environment on Stress Response, Immune Function, and Disease Resistance in Juvenile Coho (Oncorhynchus kisutch) and Chinook Salmon (O.tshawytscha)

1993 ◽  
Vol 50 (4) ◽  
pp. 759-766 ◽  
Author(s):  
Kira Salonius ◽  
George K. Iwama
Keyword(s):  
Disease Resistance ◽  
Chinook Salmon ◽  
Coho Salmon ◽  
Vibrio Anguillarum ◽  
Oncorhynchus Kisutch ◽  
Significant Rise ◽  
Wild Fish ◽  
Handling Stress ◽  
Hatchery Fish ◽  
Natural Water Body

Coho (Oncorhynchus kisutch) and chinook salmon (0. tshawytscha) from aquaculture and wild environments were subjected to handling (30–60 s of netting and aerial emersion) and disease challenges. Plasma cortisol concentrations ([cortisol]pl) in both coho and chinook salmon from wild environments were significantly elevated 4 h after handling. Colonized coho salmon (hatchery-reared fish, transported into a natural water body as fry) responded in a similar fashion to wild fish, while those reared entirely in the hatchery showed no significant rise in [cortisol]pl. The responses to handling stress were retained in wild and colonized coho salmon after 7 mo of hatchery rearing. A transient increase in the leukocyte to red blood cell ratio in both wild and hatchery-reared chinook salmon occurred 4 h after handling. Handling signficantly decreased the antibody-producing cell (APC) number in wild fish and elevated their [cortisol]plrelative to hatchery fish. Wild fish had the highest APC number among the three groups before the handling. No difference in resistance to Vibrio anguillarum was apparent in coho and chinook salmon among the different rearing environments, although chinook salmon were generally more susceptible; disease resistance was reduced in wild coho salmon after 7 mo of rearing in a hatchery.

scholarly journals FEEDING HABITS AND HELMINTH PARASITES OF SARDINE (S. PILCHARDUS) AND ANCHOVY (E. ENCRASICOLUS) IN THE ADRIATIC SEA

2015 ◽  
Vol 17 (1) ◽  
pp. 216 ◽  
Author(s):  
B. ZORICA ◽  
V. ČIKES KEČ ◽  
O. VIDJAK ◽  
I. MLADINEO ◽  
D. EZGETA BALIČ
Keyword(s):  
Diet Composition ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Stomach Content Analysis ◽  
Helminth Parasites ◽  
Significant Difference ◽  
Prey Composition ◽  
One Year ◽  
Paratenic Hosts ◽  
Hysterothylacium Aduncum

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.

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.

The Foods and Feeding Habits of Subadult Crocodylus Porosus Schneider in Northern Australia.

1979 ◽  
Vol 6 (3) ◽  
pp. 347 ◽  
Author(s):  
JA Taylor
Keyword(s):  
Feeding Habits ◽  
Stomach Contents ◽  
Northern Territory ◽  
Northern Australia ◽  
Wet Season ◽  
Flood Plains ◽  
Significant Difference ◽  
Arnhem Land ◽  
Crocodylus Porosus ◽  
Slow Moving

Stomach contents were studied for 289 live young crocodiles (Crocodylus porosus) less than 180 cm long, collected from coast, river and swamp of Arnhem Land, Melville Island and Grant Island, Northern Territory, Australia; the crocodiles were then released. Tables give orders and families and some generic and specific names for prey or carrion eaten and for 3 parasites on the crocodiles, for a dry and a wet season in 1975-76. Between crocodiles 50 to 120 cm long and those smaller or larger there was no significant difference in the proportion of crocodiles having eaten crabs, shrimps, fish or insects or with empty stomachs, but only the larger crocodiles ate mammals or birds. Frequency of different foods eaten differed significantly with type of habitat or with salinity. Weight of food or incidence of empty stomachs did not differ between seasons, habitats or salinities. Condition of the crocodiles was significantly poorer for those from freshwater swamps than for those from lower mangrove or flood plains, and highest for those from upper mangrove. Main foods in both seasons were crustaceans, mainly crabs of subfamily Sesarminae and shrimps of genus Macrobrachium. The only fish eaten regularly was Pseudogobius sp., a slow-moving fish found by the water's edge. Amphibians were not found in the stomach.

Terrestrial invertebrates as salmonid prey and nitrogen sources in streams: contrasting old-growth and young-growth riparian forests in southeastern Alaska, U.S.A.

1997 ◽  
Vol 54 (6) ◽  
pp. 1259-1269 ◽  
Author(s):  
Mark S Wipfli
Keyword(s):  
Statistical Power ◽  
Coho Salmon ◽  
Fork Length ◽  
Cutthroat Trout ◽  
Timber Harvesting ◽  
Trophic Levels ◽  
Old Growth ◽  
Nitrogen Inputs ◽  
Significant Difference ◽  
Young Growth

Terrestrial-derived invertebrate (TI) inputs into streams and predation on them by salmonids (40-180 mm fork length) were measured in six coastal Alaska stream reaches from April through October 1993-1994; riparian habitat of three stream reaches contained conifer-dominated old-growth (no timber harvesting) and three were alder-dominated young-growth (31 years postclearcutting). Data from pan-traps placed on stream surfaces showed that TI biomass and nitrogen inputs averaged up to 66 and 6 mg ·m-2 ·day-1, respectively, with no significant difference between habitats. Stomach contents from coho salmon (Oncorhynchus kisutch), cutthroat trout (O. clarki), and Dolly Varden (Salvelinus malma) revealed that TI and aquatic-derived invertebrates (AI) were equally important prey. Additionally, salmonids from young-growth systems ingested a greater TI proportion than those from old-growth systems. There were trends but no significant differences between habitats of TI and AI biomass ingested; however, statistical power was <0.30. These results showed that TI were important juvenile salmonid prey and that a riparian overstory with more alder and denser shrub understory may increase their abundance. Riparian vegetation management will likely have important consequences on trophic levels supporting predators, including but not limited to fishes.

Apparent predation of juvenile coho salmon (Oncorhynchus kisutch) by prickly sculpins (Cottus asper) is an artefact of trapping methodology

2006 ◽  
Vol 57 (5) ◽  
pp. 513 ◽  
Author(s):  
Londi M. Tomaro
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Stomach Contents ◽  
Early Life History ◽  
Boreal Summer ◽  
Life Stages ◽  
Life History Stages ◽  
Juvenile Salmonids ◽  
Freshwater Sculpin ◽  
Trap Bias

Freshwater sculpins often inhabit the same waterways as juvenile salmonids and may impact the survival of juvenile salmonids through predation on early life-history stages. In the present study, the stomach contents of 2302 individual Cottus asper, a freshwater sculpin, collected from Auke Lake, Alaska, were examined during the boreal summer of 2000 to determine if C. asper are important natural predators of juvenile coho salmon (Oncorhynchus kisutch), and to explore possible trap bias of gear used in preliminary diet studies. The diet of sculpins collected in confining traps was compared with the diet of sculpins collected in nets. Significant predation on pre-smolt coho salmon by trapped sculpins, but none by netted sculpins, was observed. This result provides strong evidence of trap bias in the observed diet of C. asper. The remainder of the diet of trapped sculpins also differed significantly from that of netted sculpins. Significantly more trapped sculpins had eaten plant material and fish, whereas significantly more netted sculpins had consumed molluscs. Finally, sculpin diet was correlated with sculpin size, which may influence predation on other salmonid life-stages. These results expand our understanding of prickly sculpin diet and show that they are not important predators of juvenile coho salmon. These findings also demonstrate the importance of assessing the potential bias of collection gear and sampling techniques.

scholarly journals Seasonal analysis of food items and feeding habits of endangered riverine catfish Rita rita (Hamilton, 1822)

2022 ◽  
Vol 82 ◽  
Author(s):  
M. A. Haque ◽  
S. Paul ◽  
M. A. S. Jewel ◽  
U. Atique ◽  
A. K. Paul ◽  
...  
Keyword(s):  
Feeding Habits ◽  
Close Association ◽  
Feeding Activity ◽  
Stomach Contents ◽  
Food Items ◽  
Significant Difference ◽  
Mouth Size ◽  
Size Groups ◽  
Food And Feeding ◽  
Seasonal Analysis

Abstract This investigation presents the food and feeding activity of and endangered riverine catfish Rita rita, during February 2017-January 2018. A total of 225 fish individuals was analyzed for stomach contents by characterizing the dominant food items and morphometric features. The results divulged ten major food items consumed, preferably fish scales and eggs, teleost fishes, copepods, cladocerans, rotifers, and mollusks. Total length and body weight of fish varied between 9-34 cm (20.53 ± 6.90 cm) and 10-400 g (9125.94 ± 102.07 g), respectively. The index of relative importance (IRI%) showed the importance of rotifers over the other food items. Morisita’s index of diet overlap indicated seasonal variations in catfish diets with summer and monsoon displaying the least overlap, while maximum overlap during monsoon and winter seasons. The non-metric multidimensional scaling (nMDS) indicated the close association between the food items available during summer and winter seasons with a significant difference among the seasons (ANOSIM, R = 0.638, P = 0.013). Levin’s niche breadth index arranged in the order of 0.88>0.81>0.78>0.63>0.43 for the size classes of V, IV, III, II and I, respectively. The PCA explained 95.39% of the total variance among the food items and fish size groups. Small-sized fish individuals displayed a greater correlation with food items suitable for their mouth size. In conclusion, the variety and frequency of food items recorded indicated considerable feeding plasticity and opportunistic feeding behavior with a shift from carnivorous to omnivorous feeding nature. This study could render useful information on the food and feeding habits of R. rita and provide background for preparing its diet for future aquaculture practices.

Changes in Cortisol Dynamics in Wild and Hatchery-Reared Juvenile Coho Salmon (Oncorhynchus kisutch) During Smoltification

1994 ◽  
Vol 51 (10) ◽  
pp. 2179-2187 ◽  
Author(s):  
J. Mark Shrimpton ◽  
Nicholas J. Bernier ◽  
David J. Randall
Keyword(s):  
Atpase Activity ◽  
Plasma Cortisol ◽  
Coho Salmon ◽  
Gradual Increase ◽  
Oncorhynchus Kisutch ◽  
Cortisol Concentration ◽  
Wild Fish ◽  
Hatchery Fish ◽  
Corticosteroid Receptor ◽  
Cr Concentration

Cortisol dynamics were examined in hatchery and wild juvenile coho salmon (Oncorhynchus kisutch) over the spring of 1991 and 1992 when the fish were smolting. Wild fish were caught in the upper Quinsam River, British Columbia and at the downstream enumeration fence when they started to migrate. Two groups of hatchery fish were from the top and bottom ends of an earthen rearing channel. Plasma cortisol levels increased during the spring in all groups, but were significantly greater in wild than in hatchery smolts. The half-life of plasma cortisol decreased as fish smolted; however, there was no difference among the groups. Corticosteroid receptor (CR) concentration and affinity decreased during the spring. Wild fish consistently possessed the greatest gill concentration of CR. The change in dissociation constant (kD) was similar for hatchery and wild fish during spring 1991. In 1992, hatchery fish showed a similar gradual increase. In contrast, wild fish did not show an increase in kD until May. The changes in cortisol concentration in the plasma and the CR kD occurred synchronously with the increase in Na+K+ATPase activity in wild fish, which showed the greatest increase in kD, plasma cortisol, and Na+K+ATPase activity.

Feeding habits of the swimming blue crab Portunus segnis (Forskål, 1775) (Brachyura: Portunidae) in the Mediterranean

2019 ◽  
Vol 99 (06) ◽  
pp. 1343-1351
Author(s):  
Olfa Ben Abdallah-Ben Hadj Hamida ◽  
Nader Ben Hadj Hamida ◽  
Rihab Ammar ◽  
Houda Chaouch ◽  
Hechmi Missaoui
Keyword(s):  
Blue Crab ◽  
Feeding Habits ◽  
Carapace Width ◽  
Stomach Contents ◽  
Food Groups ◽  
Significant Difference ◽  
Southern Mediterranean ◽  
Animal Material ◽  
Maturity Degree ◽  
Portunus Segnis

AbstractThe alien blue swimming crab, Portunus segnis (Forskål, 1775), an Indo-Pacific species, has been recorded in the southern Mediterranean Sea for decades, and its occurrence along the southern Tunisian coasts has been recorded since 2014. The feeding habits of P. segnis were studied in the Gulf of Gabes from October 2015 to September 2016. The stomach contents of 3061 crabs, ranging from 50 to 168 mm carapace width, were analysed. The stomach contents appeared to consist mainly of large quantities of crustaceans, fish and molluscs, and small quantities of echinoderms, annelids, tunicates, cnidarians, plants, unidentifiable matter and debris. The major food groups observed were crustaceans throughout the year with fish and molluscs secondly. In juvenile, sub-adult and adult crabs, crustaceans constituted the dominant food source and these were present in more than 65% of the stomachs analysed. Ingestion of fish increases as the crab matures. A significant difference (P &lt; 0.05) was observed in the quantity of the food consumed by the two sexes. The diet also increased with increasing ovary maturity degree, while the percentage of empty stomachs in ovigerous and non-ovigerous females did not show any difference. The vacuity index varied significantly in both sex (P &lt; 0.0001), among size (P &lt; 0.0001) and seasons (P &lt; 0.0001). This study shows that, despite the diversity in blue crab diets and feeding habits, it is omnivorous with a preference for animal material.

The Effect of Short-duration Seawater Exposure on the Swimming Performance of Wild and Hatchery-reared Juvenile Coho Salmon (Oncorhynchus kisutch) during Smoltification

1994 ◽  
Vol 51 (10) ◽  
pp. 2188-2194 ◽  
Author(s):  
C. J. Brauner ◽  
G. K. Iwama ◽  
D. J. Randall
Keyword(s):  
Fresh Water ◽  
Coho Salmon ◽  
Swimming Performance ◽  
Oncorhynchus Kisutch ◽  
Aerobic Metabolism ◽  
Wild Fish ◽  
Swimming Velocity ◽  
Hatchery Fish ◽  
Oxygen Carrying Capacity ◽  
Seawater Challenge

The critical swimming velocity (Ucrit) and haematology of wild and hatchery-reared coho salmon (Oncorhynchus kisutch) juveniles were examined in either fresh water or seawater following a 24-h seawater challenge, at the time of smoltification. In fresh water, wild smolts swam faster than hatchery-reared fish but this could largely be accounted for by scaling for body size. Transfer to seawater significantly elevated resting plasma [Na+] and reduced subsequent Ucrit in hatchery fish (by 12%) relative to that determined in fresh water but had no significant effect on resting plasma [Na+] and Ucrit in wild fish. Swimming the fish a second time in seawater after the initial 2-h exercise period resulted in a significant reduction in Ucrit relative to that in fresh water in both wild fish (16%) and hatchery fish (a further 14%); this relatively greater impairment in Ucrit in hatchery fish was due to a reduced hypo-osmoregulatory ability following seawater transfer that impairs conditions for muscle contractility and aerobic metabolism. Aerobic metabolism in seawater-exposed fish was affected in part through a reduction in haematocrit and an increase in plasma volume, reducing oxygen carrying capacity of the blood relative to conditions in fresh water.

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