摘要:

Bluegills (Lepomis macrochirus) were exposed to the propylene glycol butyl ether ester of 2,4-D in six ponds at Tishomingo, Oklahoma, one concentration per pond in five ponds, and a control pond. The fish and the pond environment were studied for five months to measure chronic effects on the fish and persistence of the herbicide in pond water, bottom sediments, and aquatic vegetation. Small quantities of 2,4-D were found in pond waters for six weeks after application. Residues of 2,4-D were found in vegetation and in bottom sediments in the highest-treated pond for six weeks. No 2,4-D was detected in fish after four days.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<1:SCEODO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Fathead minnows, Pimephales promelas, were exposed to endrin or DDT under static and dynamic conditions to evaluate whether the particular condition would appreciably change the apparent insecticide toxicity. Comparative 48- and 96-hour endrin exposure indicated a slightly higher LC50value during static tests as compared with dynamic tests. This may be due, in part, to the maintenance of endrin concentrations in the latter. Comparative 48-hour DDT bioassays indicated the static condition to be much more toxic than the dynamic. Because toxicity was higher in the static system, where DDT levels were decreasing rapidly, it may be reasonable to assume that decreasing oxygen concentrations and/or accumulating fish metabolites (ammonia, CO2, and others) may have enhanced the apparent toxicity of DDT during static exposure.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<13:DAEFTU>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Static acute bioassays were conducted to determine the relative susceptibility to insecticides of representatives of the families Ictaluridae, Cyprinidae, Centrarchidae, and Salmonidae. TL50values were predicted for twelve species of fish tested against nine insecticides. Species differences in susceptibility to the organochlorine insecticides DDT, toxaphene and lindane, and the phosphorothionate organophosphorus insecticides Bayrex(R)and methyl parathion were minimal. Relatively large differences in species susceptibility to the organophosphorus insecticides of the phosphorodithioate group (malathion and Guthion(R)were observed. Species differences in susceptibility to the carbamate insecticides, carbaryl and Zectran, were apparent. Susceptibility to the insecticides was, in general, similar within systematic groups, with the Ictaluridae and Cyprinidae being the least susceptible and the Salmonidae being the most susceptible of the families tested.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<20:ISOSCF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Growth in total body length and weight was described for lake whitefish, Coregonus clupeaformis (Mitchill), taken in the commercial fishery at Red Lakes, Minnesota. Growth was among the fastest when compared with that reported for other North American waters. Growth rates of males and females were similar until the end of the fourth year, but in the fifth and later years, females were slightly longer. Females reached a maximum age of 9 and males 8. Five-inch-mesh nets, fished in the fall, captured faster-growing members of age groups III and IV than the 3 1/2-inch-mesh nets fished in the summer. Fish taken in June were heavier (dressed weight) than fish of similar lengths in July and August. Records of catches and fishing effort of the fishery were described from 1917 to 1963. Great variability in age composition of commercial catches was associated with variability of strength of year classes. The 1954 year class was the major contributor in both numbers and weight to the fishery for 5 years, and was approximately 160 times stronger than the weakest year class. Strength of whitefish and walleye, Stizostedion vitreum vitreum (Mitchill), year classes were related, but no correlation of year class strength with various physical factors was found. The fishery contributed to a high annual total mortality of 70% for age II and III fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<28:LWITCF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The movement and distribution of smallmouth bass, Micropterus dolomieui, were studied in the Snake River, a large western river, prior to impoundment. A tag and recovery program was designed to assess interpool movement. Smallmouth bass were collected by angling and electrofishing. Primacord, a detonating fuse, was used to assess distribution during late fall and winter. Underwater observations were made with SCUBA apparatus. Bass behavior was studied in the laboratory and dealt principally with temperature effects, light intensity and substrate.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<44:MADOSB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

American eels, Anguilla rostrata (LeSueur), were collected from 8 New Jersey streams. Three areas on the Big Flatbrook were selected for intensive examination. Eels comprised 37% of the total weight and 20% of the total number of the 25 species of fishes collected on the Flatbrook. The weight of eels was exceeded only by the white sucker (Catostomus commersoni). Stomach content analysis of eels showed a gradual increase in size of food organisms taken with increase in size of eels. Ephemeroptera, Megaloptera, and Trichoptera were most prevalent in smaller eels (less than 40 cm) while fish and Crustacea were more frequently found in larger specimens (greater than 40 cm). Stomach contents reflected the relative abundance of organisms in bottom samples. Of the fish taken by eels as prey, bottom dwelling and sluggish species were most prevalent. Age determinations by otolith ring counts of 169 specimens showed a range of ages from 3 (less than 14.5 cm long) to 19 (approximately 85 cm long) years with a mean of 10 years.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<54:RAFHAA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A small-mesh midwater trawl was towed 83 times in Hawaiian waters during July-September 1967. Objectives were to develop techniques for collecting juveniles of skipjack tuna and other scombrids and to provide information on their distribution. A systematic trawling routine was followed in July and August off the island of Oahu. Deep. (100 m) tows were alternated with shallow (20 m) tows during the day (1200–1800 hours), night (2000–0200 hours), and morning (0400–1000 hours) for the first 57 stations. The last 26 stations included tows, primarily at shallow depth, off the islands of Molokai, Lanai, Hawaii, and Oahu. A total of 995 juvenile scombrids, representing six species, was collected. The catch included 578 skipjack tuna (Katsuwonus pelamis), 180 yellowfin tuna (Thunnus albacares), 133 frigate mackerel (Auxis sp.), 46 bigeye tuna (T. obesus), 25 kawakawa (Euthynnus affinis), and 7 albacore (T. alalunga). The largest catches of juvenile tunas were made in the offshore Oahu area about 56 km from shore in July and August and off Hawaii in September. Tows in these areas averaged about 18 tunas per tow. In contrast, tows in the inshore Oahu area about 7 km from shore averaged only three tunas per tow. Shallow tows at night tended to catch the most juvenile skipjack tuna and deep tows at night, the fewest. Catches during the morning were not significantly different from those at night, but shallow-morning tows tended to be less productive and deep-morning tows to be more productive than corresponding tows at night. Daytime catches were about the same in shallow and deep tows. The differences in the catch rates for skipjack tuna between shallow and deep tows at different times were assumed to be the result of diel vertical migration. Juvenile yellowfin and bigeye tunas either did not undertake did vertical migrations or their movements were not extensive. Almost all the bigeye and yellowfin tunas were taken in shallow tows. Skipjack tuna measured 7–47 mm standard length; most were 9–15 mm long. Skipjack tuna were significantly larger in deep tows (average 14.4 mm) than in shallow tows (average 11.1 mm) during all three towing periods. Although the apparent tendencies were not significant, night and morning tows at the deeper depth also tended to catch larger skipjack tuna than day tows. It was tentatively concluded that the smaller skipjack tuna live primarily in the upper isothermal layer, whereas the larger individuals tend to occur in deeper water.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<60:JTCBMT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Menidia audens were introduced into Upper and Lower Blue Lakes, and in Clear Lake, Lake County, during the fall of 1967, as a result of previous study indicating a high potential for this species as a biological control agent for aquatic midges, and as a forage species for game fishes. Although the species has not as yet been recovered from Upper Blue Lake, it is doing well in Lower Blue Lake, and has already become a predominant component of the fish fauna of Clear Lake.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<70:MSMAAE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Variations in the production of carp, Cyprinus carpio, were measured in four consecutive seasons in nine similar, contiguous ponds. These were believed to be the most extensive uniformity studies made of fish production in ponds. The fertility of the carp ponds varied from year to year partly due to fertilization; the means and coefficients of variation of net production in kg/ha in replicate ponds within years were, respectively: 285, 0.179; 196, 0.143; 140, 0.227; 427, 0.123. Variations in weight increments made by similar numbers of tilapia, Tilapia mossambica, were measured over 50-day periods in 10-foot diameter plastic pools having meticulously standardized soil substrates. These data suggest: 1) that carrying capacity in ponds is less stable than commonly believed, 2) that no environmental factor, such as basin fertility, maintained a dominant, continuous influence, and 3) that in each new season production was controlled by a new assortment or combination of factors.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<74:VICPIR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A surplus-yield model of fishery dynamics which assumes the Gompertz growth function is developed, resulting in an implied exponential relationship between catch per unit effort and fishing effort, and in an asymmetrical yield curve. A maximum sustainable yield, predicted by the exponential model, is obtained from a population size which is about 37% of the environmentally limited maximum size. Three methods for estimating the parameters of the exponential model, adapted from those used for the linear model of Schaefer (1954, 1957), are presented. The exponential model is compared with the linear model using examples of the fisheries for the California sardine, Sardinops caerulea (Girard), and yellowfin tuna, Thunnus albacares (Bonnaterre) of the eastern tropical Pacific and western Atlantic Oceans. Management implications are discussed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1970)99<80:AESMFO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor