摘要:

A mathematical model of trout-stream fisheries was developed that can be used to evaluate a variety of fishing regulations. Density-dependent mortality was found in the first 2 years of life for each of the two brook trout (Salvelinus fontinalis) and three brown trout (Salmo trutta) populations studied in Michigan. Regression equations were used to describe the density-dependent relationships for modeling purposes. Equations were developed that used mortality, growth, and length-frequency information to calculate the number of fish in a population, number caught and harvested, number caught and released, number of deaths due to hooking mortality, number of natural deaths, and number recruited for any time period and age-group. Also, addition of a length-weight regression allowed equations to be developed for calculating yield in weight harvested, yield in weight caught and released, and gross biomass production for any time period and age-group. Effects of imposing different types of length limits, including minimum, inverted, or slot limits, can be analyzed with this mathematical technique. Fishing mortality and hooking mortality can be adjusted to simulate values typical for different gear types. In addition, consequences of seasonal fluctuations in growth and fishing mortality, including shifts in length of fishing season or time frame, can be assessed. The equations were incorporated into a computer simulator, TROUT.DYNAMICS, and the brown trout fishery in a section of the Au Sable River, Michigan, was simulated for a period in the past and a period in the future to demonstrate applications of the model.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<587:MDOTF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Brook trout (Salvelinus fontinalis) at age 5 weighed from 65 g to 1,751 g in 23 mountain lakes located in Banff, Jasper, and Waterton Lakes national parks in Alberta. Lake area ranged from 2.2 hectares to 2,065 hectares, maximum depths from 2 m to 96 m, and elevation from 1,019 m to 2,347 m above sea level. For the 23 lakes, there were significant positive correlations between the weight of age-5 fish and the natural logarithm of amphipod densities (r = 0.73), the specific conductance of the waters (r = 0.63), and the midsummer water temperature (r = 0.55). There was a significant negative correlation between fish weight and lake elevation (r = −0.63). Analyses of brook trout stomach contents from 18 lakes indicated a cause-and-effect relationship between fish growth and amphipod abundance. A stepwise multiple regression analysis attributed 54% of the lake-to-lake variation in brook trout growth to amphipod density, 11% to maximum depth, and 7% to specific conductance. From regression analyses, several models were developed to predict the growth of brook trout. Test results indicated that the models are useful for predicting the potentials for slow, intermediate, or superior brook trout growth in mountain lakes of western Alberta.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<603:CBBTGA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Seasonal changes in dry body weight and caloric and lipid contents were studied in ages 0 and I and ages I and II gizzard shad (Dorosoma cepedianum) in 1973 and 1974, respectively. Dry body weight increases were best described by second and third order polynomial equations, with maximum values occurring in late autumn. Data on body caloric and lipid contents indicated a period of rapid storage in late summer and early autumn. Declines in average dry body weight, body calories, and body lipids occurred during the winter months. The intensity of the fattening process was greater in age-I fish than in ages 0 and II fish. The highest values of body lipids (30% of dry weight) and calories (6,909 cal/g ash-free dry weight) were observed in age-I fish on 16 November and 20 November 1973, respectively. Lipid reserves were mobilized during over-wintering and, in age-II fish, during the reproductive cycle. Energy reserves may also be utilized for body maintenance and growth when reductions occur in the availability or quality of the food supply.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<611:ESAUPO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The long-term effects (November 1977-October 1978) of elevated temperature on smallmouth bass, Micropterus dolomieui (age 0+ at stocking) were evaluated in outdoor channels located on the Tennessee River in Alabama, the southern limit of the native range of this species. Temperature treatments, with three channels per treatment, were at the ambient regime of the Tennessee River and 3, 6, and 9 C above ambient. Actual temperatures ranged from 1 to 30 C in the ambient channels and from 10 to 38 C in the +9 C channels. Under extreme summer conditions there was a 10% (by volume) refuge zone of 35 C water in the +9 C channels. Mean annual survival rates ranged from 84% in the +3 C regime to 92% in the +6 C regime; survival was 87% in both the ambient and +9 C treatments. Substantial growth occurred throughout the range 20 to 32 C. After 322 days, net biomasses of smallmouth bass in the four thermal regimes were not significantly different (range, 85–105 kg/hectare). Reproduction at age I occurred in all four regimes. The broad thermal requirements for growth and survival of smallmouth bass in this study were characteristic of warmwater species. To protect smallmouth bass from elevated temperature, the following numerical temperature criteria were derived: (1) a mean weekly average temperature of 32–33 C in the mixed water body would permit satisfactory growth; and (2) a maximum temperature of 35 C for short-term exposure during the summer growth period would avoid potential lethal effects.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<617:EOETOG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Freshly fertilized eggs of brook trout, Salvelinus fontinalis, were cold-shocked, after 1 minute of water hardening, in a 5% glycerol solution at −1.5 C for 2 hours. Egg mortality was significantly increased by this process. A chromosome analysis indicated that 33% of the brook trout hatched from cold-shocked eggs from females induced to spawn were mosaic polyploids, compared with 12% of the fry from noninduced females. No exclusively triploid brook trout were found by chromosome analysis. Frequency distributions of erythrocyte nuclear volumes indicated a higher incidence of mosaic polyploidy among fish than did chromosome counts for the same specimens. The reasons for this inconsistency are not known.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<626:PIIBTB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Critical thermal maxima (CTM) and responses to fluctuating thermal regimes indicate that adult rainbow (Salmo gairdneri), brown (Salmo trutta), and brook (Salvelinus fontinalis) trout species, introduced into the southwestern United States, are as well adapted to elevated water temperature as adult Gila (Salmo gilae) and Arizona (Salmo apache) trout, which are native to that region.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<632:CTMOFT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Concentrations of lead, zinc, nickel, and cadmium were low in streamwater samples obtained quarterly over 1 year at three sites adjacent to highways of low to moderate traffic volumes (<50, 6,550, and 15,000 vehicles per day). Sediment concentrations of lead, nickel, and zinc were highly correlated with traffic density. Stream sediments appeared to serve as the storage reservoir and primary source for bioconcentration of heavy metals. Whole body (dry weight) concentrations of heavy metals in benthic insects and fish were generally comparable to literature values for animals from contaminated waters. Lead concentrations in members of three benthic insect families were significantly correlated with traffic density, as were lead and zinc concentrations in three fish species. Two of the fish species also showed progressive increases in nickel and cadmium with traffic density. Seasonal variation in heavy metal content was evident only in sediment, with highest values during the spring period of maximum runoff.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<636:HMIASE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

This paper reports an approach for predicting general marine fishing locations and distances traveled offshore for fishing from boat equipment data. Discriminant analysis indicated that bay and offshore fishing boats could be distinguished with 80% classification accuracy from horse-power, fuel capacity, and boat length. Multiple regression analyses verified that fuel capacity and presence of radios and long range navigation (LORAN) were significant predictors of offshore fishing distances.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<644:PMRFPF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A bow-mounted pushnet designed to sample near-surface young-of-the-year pelagic fishes had a significantly higher catch rate than a stern trawl previously used. The ratio of catches (numbers of fish) for simultaneous sampling with the pushnet and two identical trawls was 23:3:1. Both gear sampled the same population with respect to fish length. The pushnet requires a crew of only two, can be operated in shoal water, and multiple net installation is possible. The outboard vessel-pushnet unit is highly mobile because the frame is readily raised for cruising and swung aft, but not detached, for trailering.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<649:DAREOA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Hydrolysis-resistant organic matter (HROM; chiefly cellulose and chitin) was not assimilated by rainbow trout (Salmo gairdneri) or by three species of tilapia (Tilapia aurea, T. mossambica, T. nilotica). Dietary ash was absorbed. For studies of digestive efficiency, HROM is a more efficient reference material than chromic oxide, and a more accurate one than ash.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<653:HOMAAR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor