摘要:

Segmentation of the angler population by catch preference. experience, and participation can help fishery managers understand diversity in consumptive preferences and attitudes among recreational anglers. Estimates of the sire and number of angler groups can also provide an understanding of the relative demand for the different types of fishing experiences sought. These types of angler information are often collected with mailed surveys, but segments of the angler population may be underrepresented because of nonresponse bias. A 10-page mail questionnaire was sent to a stratified random sample of 9,981 Texas fishing license holders. Information was collected on fishing participation. fishing experience, club membership, tournament participation. activity-specific attitudes, and opinions on fishery management options. Response rate was 62% (exclusive of surveys that could not be delivered). Adjustments for nonresponse were made with response propensity stratification. Groups of anglers were formed by conducting four hierarchical cluster analyses of six specialization variables. Nonhierarchical cluster analysis was used to determine the size of the seven groups of anglers. Groups had diverse attitudes pertaining to the size of fish sought, number of fish sought, importance of keeping the catch, and importance of catching “something.” Participation and experience also varied among groups. Tournament participation and club membership were most prevalent among higher-specialization anglers. Opinions on management options were significantly different among groups and reflected diverse consumptive orientations. Results agree with previous findings that different anglers seek different fishing experiences.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0001:SOTAPB>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Optimal designs of recreational angler surveys may require complemented surveys, in which different contact methods are used to estimate effort and catch. All common methods of estimating catch involve on-site interviews that may either be based on access (complete trip) or roving (incomplete trip) interviews. In roving surveys, anglers to be interviewed on a given day are intercepted with a probability proportional to the length of their completed fishing trip, whereas in access surveys, anglers are intercepted as they leave the fishery and are intercepted with the same probability regardless of the length of their completed fishing trip. There are four complemented survey designs which use interviews at access points (mail–access, telephone–access, aerial–access, and roving–access); there are four corresponding designs which use roving interviews (mail–roving. telephone–roving, aerial–roving, and roving–roving). For all of these surveys, total catch is estimated as the product of total effort and catch rate. We show that, when access interviews are used, the appropriate catch rate estimator is the ratio of means estimator (i.e., mean catch from interviews divided by mean effort); whereas when roving interviews are used, the appropriate estimator is the mean of the individual ratios of catch divided by effort for each angler. In the roving method, it is necessary to ignore short trips of less than about 0.5 h duration when calculating the mean of the ratios. This stabilizes the variance of the estimates and does not appear to cause any appreciable bias. A bias occurs in the estimates of catch rate and total catch from roving interviews when anglers are subject to a bag limit. This bias can be substantial if the bag limit is effective in limiting the catch.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0011:CREFRA>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We developed habitat suitability criteria and tested their transferability for nine fishes inhabiting unregulated Piedmont and Coastal Plain streams in Alabama. Criteria for optimal habitat were defined as those ranges of depth, velocity, substrate type, and cover type for which a species' suitability index (proportional abundance divided by proportional habitat availability, scaled from 0 to I ) equalled or exceeded 0.4. We evaluated the transferability of criteria between study sites by testing the null hypothesis that species occurrence in a sample was independent of whether or not the sample was taken in optimal habitat. We also tested criteria transference to a large, flow-regulated river sampled during low-flow periods. Depth, velocity, and most substrate criteria developed for the bronze darterPercina palmarissuccessfully transferred between unregulated streams and to the flow-regulated river samples. All criteria developed for a pair of closely related, allopatric darter species. the newly described lipstick darterEtheostoma chuckwachatteand the greenbreast darterE. jordani, transferred successfully when applied between species (in the unregulated sites) and to the regulated river samples. In contrast, criteria for the Alabama shinerCyprinella callistiafailed nearly all tests of transferability. Criteria for the speckled darterE. stigmaeum, the blackbanded darterP. nigrofasciata, an undescribedPercinaspecies, and a pair of related, allopatricCyprinellaspecies transferred inconsistently. The species with good criteria transference had high suitability indices for the shallow depths. fast current velocities. and coarse substrates characteristic of riffle species. We suggest that microhabitat criteria for riffle fishes are more likely to provide a transferable measure of habitat quality than criteria for fishes that, although restricted to fluvial habitats, commonly occupy a variety of pool and riffle habitats.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0020:TOHSCF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Artificial swim bladder deflation was examined as a technique to increase postrelease survival of largemouth bassMicropterus salmoidescaught from deep water. Depressurization was simulated with a hyperbaric chamber. Largemouth bass showed clinical depressurization signs when depressurized from a simulated depth of 3.5 m and were unable to immediately submerge when depressurized from 8.4 m. When depressurized from a simulated depth of 10.5 m, largemouth bass experienced 0% mortality when subsequently held at 14°C but 78% mortality when held at 28°C. Survivors floated for more than 6 h, a response that could expose them to higher water temperatures in stratified lakes and to increased predation, illegal harvest, and injury. Depressurized largemouth bass that had their swim bladders deflated by being punctured with a hypodermic needle were able to submerge and experienced no mortality when transferred to 14°C or 28°C. The punctured swim bladders were functional immediately. Growth over 4 weeks did not differ significantly (P> 0.05) between largemouth bass with or without artificially deflated swim bladders, and no deaths occurred over this period. We recommend artificial swim bladder deflation for largemouth bass showing depressurization signs and caught from depths greater than 6 m.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0032:LEOASB>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Collection techniques were developed for monitoring populations of triploid grass carpCtenopharyngodon idellastocked into the Santee-Cooper reservoirs, South Carolina, to control hydrillaHydrilla verticillata. Skilled bowfishers, who were paid a bounty of US$50.00 per fish, collected 69, 125, and 160 triploid grass carp in 1992, 1993, and 1994, respectively. Fish were fully vulnerable to bowfishing by age 2. Examination of sectioned utricular otoliths (lapilli) revealed annual marks formed during May–June. Weight (W) increased linearly with age (t, years), for ages 1–6;W= –2,360 + 3,016t. Age-specific weights ranged from 0.39 kg to 15.68 kg for fish of ages 1–6. The weight to total length (TL, mm) relation varied little during the study and wasW= 0.00000425(TL)3.185. A von Bertalanffy growth equation was fitted to describe the relation between length and age. TLt= 1,044(1 –e–0.615(t– 0.590)). The annual rate of mortality was 22% in 1994. We estimate that 350,000 triploid grass carp, weighing about 2,000,000 kg, were present in the system as of August 1994; this represented approximately 17 grass carp, or 97 kg, per vegetated hectare. Collection and aging techniques developed in this study may have application in places where triploid grass carp are conservatively and incrementally stocked into large systems. In this regard, population density and growth can be monitored and future stockings adjusted accordingly.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0038:CAGAPA>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The relative weight (Wr) index of body condition provided insight into the stock dynamics of walleyeStizostedion vitreumin six reservoirs in the North Platte River drainage of Wyoming. The three most upstream reservoirs are managed as both walleye and trout (Oncorhynchusspp. andSalmospp.) fisheries; trout are stocked annually. The three downstream reservoirs are managed for coolwater and warmwater fishes, and walleye fry are stocked almost annually in two of the reservoirs. Positive relations between stocking densities of trout andWrof walleyes and between water levels andWrof walleyes were observed. Length-related trends inWrwithin walleye stocks over time were related to prey availability.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0044:TIRWOW>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We used an individual-based model of sympatric rainbow troutOncorhynchus mykissand brook troutSalvelinus fontinalisto evaluate management strategies for enhancing brook trout densities in southern Appalachian streams. Management strategies examined with 100-year simulations were (1) electrofishing removal of rainbow trout, (2) stocking of brook trout, (3) habitat alteration (changing mean size of pools in the stream), and (4) angler harvest of rainbow trout. Results indicated that realistic levels of electrofishing removal of rainbow trout and stocking of brook trout juveniles could lead to brook trout densities equivalent to those of allopatric populations, but that habitat alteration and angler harvest of rainbow trout would not significantly increase brook trout densities. Electrofishing and stocking results were robust because similar predictions were obtained under conditions that otherwise favored rainbow trout (invasion of rainbow trout adults, frequent year-class failures, reductions in spawning habitat). Ten to 20 years were required for allopatric-equivalent brook trout densities to be achieved. Management strategies that reduce interspecific competition in the age-0 life stages offer the most promise for restoring brook trout stocks in southern Appalachian streams.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0054:AIBMAO>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We assessed first winter habitat use by placing wild rainbow troutOncorhynchus mykiss(52–155 mm total length) in wire-mesh enclosures with different cover treatments and at varying fish densities. Cobble–boulders substrates (20–40 cm diameter) were arranged in four different configurations: (1) no cobble–boulders, (2) cobble–boulders present but not touching, (3) cobble–boulders touching in a single layer, and (4) cobble–boulders touching and stacked in two layers. As the configuration of rock substrate was changed to create more concealment cover, the number of fish remaining in the enclosures after 96 h increased significantly, even though the quantity of rock substrate did not change. The initial stocking density of fish had no overall significant effect on the number of fish remaining in enclosures after 96 h. However, analysis of each cover × density treatment showed that when the substrate arrangement created little concealment cover, the number of fish remaining in the enclosures did not increase with an increase in initial fish density, but when the substrate arrangement created relatively more concealment cover, more fish remained in the enclosures when the initial fish density was increased. In trials with rock cover present, fish emigrating from the enclosures were larger than those remaining in the enclosures. Our results demonstrate the importance of the configuration of cobble–boulders substrate in determining its suitability as winter cover for rainbow trout.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0077:EOCBSC>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We sampled 19 isolated headwater populations of westslope cutthroat troutOncorhynchus clarki lewisiin Montana to provide estimates of fecundity, longevity, sex ratio, and age at sexual maturity. Fecundity was estimated for 31 fish collected from two streams in the upper Missouri River drainage. Females smaller than 149 mm fork length (FL) were generally immature and their fecundities could not be estimated. Mean fecundities (SD) were 227 eggs (41.1) for 150–174-mm fish, 346 eggs (85.6) for 175–199-mm fish, and 459 eggs (150.8) for 200-mm and larger fish. A linear regression model (two stream samples combined) to predict fecundity (E) from fork length was developed (E= –494.9 + 4.4sFL;r2= 0.51,P< 0.001) for westslope cutthroat trout in the upper Missouri River drainage. Regression slopes of fecundity against fish length differed significantly (P< 0.01) between these and some of the previously studied populations. Steeper slopes were associated with lacustrine-adfluvial populations. The average sex ratio was 1.3 males per female across all sampled streams. Males began to mature sexually at age 2 and all were mature by age 4. Some females (27%) were sexually mature at age 3 and most of them (93%) were mature by age 5. Length was a better predictor of sexual maturity than age. Males matured at 110–160 mm and females at 150–180 mm FL. The maximum estimated age was 8 years based on otoliths from 475 fish collected from our 19 study streams and 14 additional streams.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0085:AASMSR>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We develop a model of the travel time of juvenile salmonids migrating through a river r each. The model is derived from an advection–diffusion equation with an absorbing boundary at the downstream collection site. The resulting travel time distribution is determined by two biologically meaningful parameters: migration rate and the rate of population spreading. The model is applied to travel time distributions for 46 cohorts of juvenile spring chinook salmonOncorhynchus tshawytschamigrating through the Lower Granite Pool (52 km in length) in the Snake River. Parameters are estimated using maximum likelihood. A PearsonX2goodness-of-fit test shows that the model is not rejected (∝ = 0.05) for the majority of cohorts.

ISSN:0275-5947    

DOI:10.1577/1548-8675(1997)017<0093:AMOTTT>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor