Proceedings of the First International Snakehead Symposium

<em>Abstract.</em>—The nonnative Northern Snakehead <em>Channa argus </em>was first documented in the Potomac River system in 2004. Since then, their range in Virginia has expanded to include other rivers and numerous lakes as a result of dispersal and illegal introductions. Most Northern Snakehead lake populations were discovered after 2012. Through 2017, nearly 4,000 Northern Snakehead were collected via Virginia Department of Game and Inland Fisheries (VDGIF) electrofishing surveys, resulting in a robust dataset. These collections provided an opportunity to investigate food habits of Northern Snakehead in both lotic and lentic systems which may assist with management and a better understanding of potential community effects. Incidence of identifiable prey items (<em>n </em>= 677) was evaluated since 2004, however wet weights (<em>n </em>= 370) were not recorded until 2014. A total of 30 prey types were identified from Northern Snakehead stomachs taken from rivers, whereas 7 prey types were identified from lakes. Banded Killifish, Bluegill, and crayfish were the most abundant prey types (in order) based on frequency of occurrence for Northern Snakehead collected from rivers; whereas Bluegill, frogs, and Yellow Perch were most common in Northern Snakehead collected from lakes. Most important food types (in order) based on % wet weight for Northern Snakehead collected from rivers were Bluegill, Gizzard Shad, and Banded Killifish; whereas Bluegill, Yellow Perch, and frogs contributed the most mass for Northern Snakehead from lakes.

<em>Abstract.—</em>Yellow-phase American eels <em>Anguilla rostrata </em>migrate upstream extensively in Atlantic coastal river systems. However, few studies have focused on movements of large yellow American eels near dams in upper watersheds of Atlantic coastal rivers. We examined relationships between environmental variables (stream flow, water temperature, and lunar phase) and movements of radio-tagged yellow American eels (518–810 mm TL) near Millville hydroelectric dam in the lower Shenandoah River drainage of the upper watershed of the Potomac River system, West Virginia. Movements of yellow American eels differed seasonally. Water temperature and stream flow were associated with upstream migration during spring. Downstream movements during fall coincided with decreasing water temperatures and darker nights near the new moon. Eels overwintered in thermal refuge areas near tributary mouths. Localized irregular upstream and downstream movements during summer occurred near dusk and dawn and possibly reflected crepuscular foraging. Our study in the Potomac River drainage suggests the need for upstream eel passage at hydroelectric facilities when spring water temperatures exceed 15°C.


<em>Abstract</em>.—Extensive fish kills, primarily from dissolved oxygen depletion, were reported in rivers and associated backwaters throughout southern Mississippi following Hurricane Katrina. Of particular concern were fisheries associated with the Pascagoula River, the last physically unmodified large river system in the contiguous United States. Posthurricane stock assessments were conducted in 2006 to ascertain appropriate fisheries restoration actions for this internationally recognized natural resource. Emphasis focused on fishes that traditionally supported recreational, artisanal, and subsistence fisheries, primarily sunfish (Centrarchidae) and catfish (Ictaluridae). These fisheries were considered some of the more productive inland fisheries in the state prior to the storm.


2012 ◽  
Vol 21 (3) ◽  
pp. 443-452 ◽  
Author(s):  
Ryan K. Saylor ◽  
Nicolas W.R. Lapointe ◽  
Paul L. Angermeier
Keyword(s):  

1991 ◽  
Vol 69 (2) ◽  
pp. 456-461 ◽  
Author(s):  
Karl Schwalme ◽  
William C. Mackay

To identify the mechanisms that elevate the glucose concentration of muscle and liver in yellow perch after exercise–handling, we exercised–handled perch for 10 min and measured subsequent changes in the glucose, glycogen, lactate, and pyruvate content of liver and muscle. By 15 min after the start of exercise–handling, the average glucose concentration had increased from 40 to 200 mg/100 g in liver, from about 6 to 18 mg/100 g in muscle, and in one of two experiments the average liver glycogen level declined from 4.0 to 2.2% wet weight. The increases in liver and muscle glucose content within 15 min were too large to be accounted for by the disappearance of muscle lactate (via the Cori cycle) and likely resulted from glycogenolysis or gluconeogenesis (from nonlactate substrates) in the liver. However, the Cori cycle, gluconeogenesis from glycerol and amino acids, and inhibition of glucose catabolism by preferential oxidation of lactate could all have contributed to prolonging hyperglycemia in muscle and liver, which lasted more than 12 h. Perch excreted about 7% of the total muscle lactate burden produced during exercise–handling stress.


2013 ◽  
Vol 16 (4) ◽  
pp. 415-424 ◽  
Author(s):  
M. K. Das ◽  
A. P. Sharma ◽  
S. K. Sahu ◽  
P. K. Srivastava ◽  
A. Rej

Fishes ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 58
Author(s):  
Marco Ferreira ◽  
João Gago ◽  
Filipe Ribeiro

Biological invasions are considered to be one of the leading causes of biodiversity loss worldwide. Freshwater ecosystems are amongst the most biodiverse, containing about 50% of the world’s known fish species but, ironically, are the most invaded ecosystems. In Portuguese freshwaters, there are currently 20 identified non-native fishes, arriving at an unprecedented rate of a new species every two years. A recent non-native is the European catfish Silurus glanis, a top predator native to Central and Eastern Europe, that arrived at the Lower Tagus (Portugal) circa 2006. This study compares the dietary habits of this top predator in two different habitats of the Lower Tagus in order to evaluate its potential impact. The stomach contents of 96 individuals were analyzed, 61 from the lotic environment and 35 from the lentic systems. A total of 66 stomachs contained prey items, 38 from the lotic and 28 from the lentic. Diet varied considerably between habitats, with shrimp and crayfish being the most abundant prey items in the lentic systems and shrimp and fish the most abundant prey items in the lotic section. Tendency to piscivory was observed in large-sized individuals. Overall, the findings in this study provide the first evidence of the potential impacts of European catfish through predation on the fish communities.


2005 ◽  
Vol 134 (6) ◽  
pp. 1605-1609 ◽  
Author(s):  
John Odenkirk ◽  
Steve Owens
Keyword(s):  

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