摘要:

Food of the pelagic young of walleye (Stizostedion vitreum vitreum), yellow perch (Perca flavescens), yellow and white bass (Morone spp.), black and white crappies (Pomoxis spp.), spottail shiner (Notropis hudsonius), and carp (Cyprinus carpio) captured concurrently in townet hauls in 1972 was compared with zooplankton samples. Each fish species differed slightly in food selection. Selective feeding by cohabiting pelagic larvae might have been a contributing factor to the strong walleye year class produced.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<77:FOTPYO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A study of the diel feeding cycle of 940 Mississippi silversides, Menidia audens Hay, in two 24-hour sampling periods in Clear Lake, California, showed a predominance of crustacean zooplankton in the diet. Ceriodaphnia sp., Daphnia pulex, and emerging dipterans were the most important food items. A pronounced morning feeding peak indicated visual feeding. Evidence of visual feeding is further given by statistically significant ingestion of larger food items at night and decreased feeding during the one moonless night. Occurrence of emerging midges in the diet during the second period indicates possible selective predation.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<84:DFCASE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Ivlev's electivity index (E) was used to assess selective feeding by the alewife (Alosa pseudoharengus) on crustacean zooplankton in southern Green Bay, Lake Michigan. Alewives positively selected larger species of Copepoda, especially Mesocyclops edax. Alewives appeared to negatively select all Cladocera. However, field data from Lake Michigan and other lakes containing abundant populations of alewives indicate positive selection may be occurring on Daphnia. Positive selection of Daphnia by alewives probably took place in southern Green Bay, although this was not indicated in electivity indices. Laboratory studies revealed that Daphnia were digested most rapidly by alewives and, therefore, were under-represented in stomach contents relative to other planktonic species. Consequently, it is suggested that differential digestion rates of prey organisms may also occur in alimentary tracts of other fish species. This could have an effect on interpretation of selective feeding data using Ivlev's electivity formula with other planktivorous fishes. The analysis of the composition of micro-crustacean cuticle as it relates to differential digestion of various planktonic species in fish stomachs is deserving of further research.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<89:TEODDR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The temperature tolerance and temperature preference of mature and young-of-year alewives from Lake Michigan were studied in the laboratory. Critical thermal maxima and incipient upper lethal temperatures increase with acclimation temperature for both mature and young-of-year fish. Critical thermal maxima at equivalent acclimation temperatures are unaffected by age of the fish. Incipient upper lethal limits for young-of-year fish exceed those for mature fish by 3 C to 6 C. The ultimate lower lethal temperature for mature alewives appears to exceed 3 C. Loss of heat tolerance following a 10 C decrease in temperature occurs at approximately one-half the rate of gain of heat tolerance following a comparable temperature increase.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<96:LAPTOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Ventilation and oxygen consumption rates of green sunfish exposed to bentonite clay suspensions were measured at 5, 15, 25, and 35 C. Ventilation rates were not affected by bentonite clay suspensions below 2,125 FTU (Formazin Turbidity Units) at 5 C, 1,012 FTU at 15 C, and 898 FTU at 25 C. At turbidity levels exceeding 1,012 FTU at 15 C and 898 FTU at 25 C ventilation rates increased 50-70%. Tests were inconclusive at 35 C due to high mortality. Oxygen consumption rates were not affected by turbid suspensions of up to 3,500 FTU at any of the four temperatures. Evidence suggests that increased ventilation rates under highly turbid conditions are a means of compensating for reduced respiratory efficiency and a strategy for maintaining a constant oxygen uptake. The costs of increased ventilation rates were probably met by a reduction in activity.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<107:EOTOVR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A high incidence of gas bubble disease was found among sahnonids and shad sampled from the air-supersaturated Columbia River. Post-capture eye damage to sockeye salmon also may be related to supersaturation of the river.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<114:OOGBDA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Gas supersaturation in aquaria can be relieved by treatment of inflowing water with suitable apparatus. Two devices have been developed for this purpose. The first uses controlled agitation of falling water to bring about equilibrium and operates at flow rates near 40 liters/min; the second agitates the seawater with compressed air and is useful in the flow rate range 0 to 3 liters/min. These designs are modifiable to other flow rates.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<116:TDFRSG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Activated carbon was effective in removing fish toxicants and anesthetics from water solutions. Its capacity to adsorb 3-trifluoromethyl-4-nitrophenol (TFM), antimycin, Noxfish(R)(5% rotenone), Dibrom(R), juglone, MS-222, and benzocaine ranged from 0.1 to 64 mg per gram of carbon. The adsorptive capacity (end point considered as a significant discharge) of activated carbon for removal of TFM was determined at column depths of 15, 30, and 60 cm; temperatures of 7, 12, 17, and 22 C; pH's of 6.5, 7.5, 8.5, and 9.5; and flow rates of 50, 78, 100, 200, and 940 ml/min. Adsorptive capacity increased when the contact time was increased by reducing the flow rate or increasing the column depth. The adsorptive capacity was not significantly influenced by temperature but was substantially higher at pH 6.5 than at the other pH's tested. A practical and efficient filter for purifying chemically treated water was developed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<119:ROTCFW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The fate of DDE and lindane added to the epilimnion of a thermally-stratified, flooded limestone quarry was followed for one year. DDE was distributed rapidly throughout the system, due to an influx of sediment generated by a rainstorm, while lindane persisted in the epilimnion until turnover. Concentration factors for zooplankton at equilibrium averaged 33 for lindane and 4.5 × 104for DDE, while the same values for bluegill were 768 and 1.1 × 105, respectively. Rainbow trout planted 134 days after treatment showed a concentration factor for DDE of 1.8 × 105within 108 days, even though less than 1 part per trillion of DDE remained in the water. The distributions of DDE and lindane in the system were controlled chiefly by sediment-water interactions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<124:DALIAL>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The catch efficiency q of two electric shrimp trawl systems, fishing two commercially important species of shrimp, was determined. The variables which determined the efficiency of electric shrimp trawls are identified and defined. The efficiency of the two electric shrimp trawl systems were predicted with a mathematical model. Field studies indicated that the predictive model for Penaeus duorarum and P. aztecus is accurate to within 5% of the measured catch efficiency values. The predicted average catch efficiency value for a 21-m electric shrimp trawl was q* = 39% of the shrimp within its path as compared to q = 35% actual efficiency measured in the field. The predicted average efficiency value for a 15-m electric shrimp trawl was q* = 54% as compared to q = 54% measured in situ.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1976)105<135:ESTCEF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor