摘要:

The long-term effect of lime neutralized suspended iron on fathead minnow (Pimephales promelas) survival, growth, and reproduction was assessed in a flow-through environment with a modified proportional diluter. Results of 12 months of testing reveal lower survival and declining growth of fathead minnows with an increase in lime neutralized suspended iron concentration. Hatchability and growth of fathead minnows were appreciably reduced in the lowest insoluble iron concentration tested, 1.5 mg Fe/liter. Reduced hatchability was attributed to the higher percentage of smaller particles in low lime neutralized iron concentrations. A comparison of data on survival, growth, and hatchability indicates that the safe level of suspended iron for fathead minnows presumably lies between the control and 1.5 mg Fe/liter.

ISSN:0706-652X    

DOI:10.1139/f73-185

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The following species of the genusLyrodiscusare recorded from Great Lakes fishes, and comparatively or originally described:Lyrodiscus rupestrisn.sp., fromAmbloplites rupestrisof lakes Ontario, Erie, and Huron:L.longibasusfromPomoxis nigromaculatusandP.annularisfrom lakes Erie and Ontario.Lyrodiscus seminolensisfromLepomis macrochirusof lakes Erie and Ontario, andL.minimusfromAmbloplites rupestrisof Lake Ontario. The genusLyrodiscusis emended.

ISSN:0706-652X    

DOI:10.1139/f73-186

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Dense schools of spottail shiners (Notropis hudsonius) are common in shallow water in Beaver Lake, generally 0.25–0.30 m below the surface, with smaller individuals more numerous towards the top. Position in the shcool is maintained by short radius behavior. The course of an individual is maintained by a beat of the tail, a glide, a hesitation, and a change of direction. Each glide path represents the chord of an arc of short radius about some neighbor. Shiners respond to disturbance by flash expansion of loose cruising association. Schooling is obligatory. The black caudal spot is probaly multifunctional as a recognition mark and releaser.Yellow perch (Perca flavescens) show an ontogeny of behavior through young-of-the-year, aggregation-sized perch (aggp), subadults, and adults. They behave as individuals or associate as streams. Disturbance will cause a group ofaggpto disperse or to stream. The adult manifestation of streaming is pack-hunting. The activity of one perch attracts the attention of others; this leads to streaming or pack-hunting. Pack-hunting improves the chance of some members of the pack, not necessarily the initiator, capturing active prey, by countering the allaesthetic protean escape reactions of organisms such as the spottail shiner. Large mixed aggregations of spottail shiners andaggpare fortuitous.Northern pike (Esox lucius) are lone, opportunistic predators whose hunting technique combines in sequence motionlessness, axial tracking, and lunging. Prey may be swallowed head- or tailfirst, or sideways.The species studied here show a range of gregariousness, from the solitary pike, through the facultative nonpolarized and polarized schools of perch, to obligate nonpolarized and polarized schools of shiners.

ISSN:0706-652X    

DOI:10.1139/f73-187

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

In a study of energy flow through the stickleback population of Ikroavik Lake, northern Alaska, oxygen consumption was related to weight and temperature by the equation Log Y = −2.795 +.823 W +.094 T where Y = μl∙min−1O2uptake; W = log weight, mg; and T = temperature. Growth was fairly rapid, with fish reaching about 21 mm at the end of the first year, 42 mm by the second, and 65 mm by the third. No older fish were found. Food was primarily chironomid larvae and zooplankton, especially copepods andDaphnia. Estimates of daily ration were calculated from growth and metabolic data (23.4 cal/day for a 30-mm fish at 10 C), gastric clearing rate determinations (12.2 cal/day at 15 C), and laboratory feeding experiments (24 cal/day at 10 C). Population distribution was uneven. Higher densities were reached in early summer, up to 74 g/m2in the marginal marsh areas. For specified days when temperatures were accurately known, an energy budget could be calculated for the population in given areas, including estimates of population biomass, respiration, growth, ration, and growth efficienc

ISSN:0706-652X    

DOI:10.1139/f73-188

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Specific growth rates were obtained for sockeye fry (Oncorhynchus nerka) acclimated to four temperatures and fed excess ration over a 36-day period, starting at an initial weight of 0.4 g. The rates were 2.2 (5 C), 5.1 (10 C), 6.5 (15 C), and 6.1 (20 C)% wet weight/day. Continuous feeding for 15 hr/day at 20 C produced a significantly greater growth rate than feeding to satiation three times daily (P < 0.05). The growth rates are compared to those obtained for larger sockeye, determined in earlier experiments.

ISSN:0706-652X    

DOI:10.1139/f73-189

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Most of the young fish of nine species that were entrained in the condenser cooling-water system of the Connecticut Yankee nuclear power plant were dead by the time they reached the lower end of the plant’s 1.83-km (1.14 mile) long discharge canal. Sampling during June and July, when 95% of the nonscreenable fish were abundant near the plant’s intake, showed that approximately 80% of the mortality in the canal was caused by mechanical damage and 20% was attributed to heat shock and prolonged exposure to temperatures elevated above 28 C. There was no measurable mortality due to the injection of sodium hypochlorite into the system as a biocide. The number of nonscreenable living fish entrained at the intake averaged about 4% (range, 1.7–5.8%) of those passing by the plant under conditions of unidirectional net tidal flow.

ISSN:0706-652X    

DOI:10.1139/f73-190

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Addition of formaldehyde to fresh cod muscle, to give concentrations of 10 to 200 ppm, brought about marked decreases in the extractable protein content during holding periods of 24 hr or less at 0 C. Similar levels of formaldehyde, produced during frozen storage of gadoid (Atlantic cod,Gadus morhua, pollock,Pollachius virens, cusk,Brosme brosme, and silver hake,Merluccius bilinearis), fillets at −5 C, brought about similar reductions in the extractable proteins. Comparative tests showed that, in the concentrations normally encountered in deteriorating frozen gadoid fillets, formaldehyde was a much more active protein-insolubilizing agent than free fatty acid. It is evident that in these protein changes more than one mechanism is involved. Observed species-differences in the extent to which fish proteins became insolubilized during storage appeared to be related to presence or absence of these different mechanisms. The more rapid and more extensive denaturation of most gadoid fillets in frozen storage than of fillets of nongadoid species appears to be directly related to the presence of muscle enzyme of the former group that is capable of producing formaldehyde from trimethylamine oxide, which is absent in the muscle of the nongadoid species so far tested.

ISSN:0706-652X    

DOI:10.1139/f73-191

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Two isolated populations of Arctic char (Salvelinus alpinus) in spring-fed tributaries of the Canning River, Alaska, had meristic characters that corresponded to those of the Western Arctic–Bering Sea form of Arctic char. The two populations demonstrated slight differences in growth rates, age at maturity, longevity, and food habits. The fish were characterized by small size (maximum 235 mm), low growth rates, low fecundities (maximum 199 eggs), and annual spawning after maturity. Mature fish were darkly pigmented and parr marks were retained throughout life. The spawning season appeared to be sometime in November, when the eggs of mature females averaged 3.8 mm in diameter.

ISSN:0706-652X    

DOI:10.1139/f73-192

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Growth of trout-perch (Percopsis omiscomaycus) in the first 2 years of life was somewhat slower in southeastern Lake Michigan (average length at end of second year, 83 mm) than in Lower Red Lake, Minnesota (90 mm), but considerably faster than in Lake Superior (58 mm); size differences in later years were slightly less pronounced. Young fish began growing earlier in the year (some before June 20) than older ones (as late as August). Females tended to live longer than males, as they do in Lower Red Lake and Lake Superior.Trout-perch spawned from late June or early July until late September, somewhat later than in Lower Red Lake (May to August) or Lake Erie (June to August). Fecundity was similar to that in Lake Erie; mature females 94–146 mm long contained from 126 to 1329 yolked eggs.

ISSN:0706-652X    

DOI:10.1139/f73-193

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Maximum growth rate of juvenile smallmouth bass (Micropterus dolomieui), grown at constant temperatures of 16, 23, 26, 29, 32, and 35 C, occurred at approximately 26 C. Fish held at 35 C demonstrated a negative growth rate. The average 96-hr low temperatureTL50 values (median tolerance limit) varied from 1.6 to 10.1 C for smallmouth bass acclimated to 15 and 26 C, respectively. Intermediate values were obtained for fish acclimated to 18 and 22 C. An important aspect of the study was the occurrence of a secondary fungous infection on the fish after 96-hr exposure to cold temperatures. In some cases the infection was severe enough to cause complete mortality within 7 days.

ISSN:0706-652X    

DOI:10.1139/f73-194

出版商:NRC Research Press    

年代:1973

数据来源: NRC