摘要:

This paper reviews the application of several sensory signals for their possible use in the control and modification of fish behavior but emphasizes the use of sound. Basic principles of underwater acoustics are introduced, followed by an overview of the structures and function of the fish ear and lateral line. Sounds in the sonic, infrasonic, and ultrasonic ranges are potentially useful for controlling fish behavior. However, most experiments testing the usefulness of such sounds have given ambiguous results except when ultrasound has been used to control some clupeid species. Very little is known about the potential usefulness of chemical and electric signals (other than electric shocks) for behavioral control. A substantial literature on the use of light to attract or repel fish offers encouraging possibilities for this control medium in some circumstances. We conclude that too little is actually known about the suitability of various signals for control of fish behavior. Many variables, such as time of day and age of the fish, affect the effectiveness even of signals that seem to “work.” These variables can influence the success or failure of a technique and need to be considered in the evaluation of any stimulus considered for the control fish behavior. Moreover, it is increasingly apparent that flow field has a powerful effect on the local success of one stimulus or another. We suggest that sound and light be further explored for control of fish behavior, particularly in combination. This work cannot be done with only field studies or only laboratory studies or by only applied biologists or only basic scientists; all methods and expertise are needed. Finally, no behavioral control method will work unless the behavior of the subject species is thoroughly understood in each place of application.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0673:AOSAOS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Researchers have often suggested that abiotic conditions influence interactions among salmonids in general and between brook troutSalvelinus fontinalisand rainbow troutOncorhynchus mykissin particular with brook trout having an advantage at lower temperatures and slower, deeper habitats (i.e., pools). In artificial stream channels, we tested whether temperature (13°C and 18°C) and macrohabitat (riffle and pool) affected aggressive interactions, foraging success, and growth rates of interspecific pairs of juvenile brook trout and rainbow trout. Brook trout were significantly more aggressive, captured significantly more prey, and had significantly greater growth rates than rainbow trout at both 13°C and 18°C. The differential effect of temperature on aggressive interactions between the species was significant; a greater difference was found at 13°C than at 18°C. However, this did not lead to a temperature-based shift in behavioral dominance because brook trout dominated rainbow trout at both temperatures. Overall, we recorded significantly greater growth rates and significantly fewer aggressive interactions and prey captures at 13°C than at 18°C. Macrohabitat did not significantly affect aggressive interactions or foraging success, but growth rates were significantly greater in riffles than in pools for both species. Macrohabitat had no differential effect on brook trout and rainbow trout. Our results suggest that differential effects of temperature and macrohabitat are not sufficient explanations of observed brook trout and rainbow trout distributions in streams.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0708:EOTAMO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Growth rates of age-0 brown troutSalmo truttaduring the growing period (May–September) were estimated in nine consecutive year-classes in three sites of Arroyo Chabatchos (Esva River basin, northern Spain). Observed growth rates were highly correlated with average water temperature, which explained 48, 68 (90% excluding the severe drought of 1989), and 89% of the interannual variation in respective growth rates at the three sites studied. Observed growth rates varied from those predicted by a model by Elliott and others, which predicted higher-than-observed growth rates in winter and negligible growth in summer. Observed growth rates were consistently higher than those predicted in two sites, and the only four instances (out of 27 possible) of lower-than-predicted growth rates occurred in fish at the site at which observed growth was slowest. As expected from the model, the predicted growth rates were also correlated with water temperature, but the slopes of the observed and predicted regressions differed significantly. The faster growth at higher temperatures exhibited by Chabatchos brown trout may be a local adaptation of the thermal regulation of growth. This adaptation does not seem to have induced a shift to a higher optimal growth temperature but only a slower reduction of growth rates with increasing water temperature. This allows Chabatchos brown trout to maintain growth that is greater than other brown trout at comparable temperatures, enabling these fish to achieve larger sizes in most growing seasons.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0718:FAOTIO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Naturally occurring stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) can be used to differentiate pelagic and benthic prey items and to characterize the trophic position of aquatic organisms. The isotopic signatures of age-0 smallmouth bassMicropterus dolomieufrom six broods in Lake Opeongo, Ontario, were tracked between June 18 and July 24, 1995. Posthatch embryos (4–5 mm in total length) had elevated δ15N values (9‰) that were attributed to the parental origin of their nitrogen pool. The δ15N decreased rapidly, approaching 2‰ for 15-mm smallmouth bass; this complete dilution of the parentally derived δ15N pool corresponded with metamorphosis from larvae into juveniles. The dramatic decline in δ15N provided an opportunity to model the relative importance of somatic growth and tissue turnover in isotopic shifts; tissue accumulation (from exogenous feeding) accounted for 86% of the observed decline in δ15N. Nitrogen isotopes indicated a dietary shift and an increase in trophic position between 17 and 46 mm. By the final sampling date (July 24), body size of age-0 fish ranged from 38 to 46 mm; a positive relationship between δ15N and body size suggested that intrapopulation trophic differences may be responsible for the observed variation in body size. The δ13C values of premetamorphosis (<15-mm) smallmouth bass (−23.2‰ to −26.1‰) were generally higher than adult δ13C values (−25.0‰ to −28.4‰). The δ13C of juvenile smallmouth bass increased with body size (from −24‰ to −21‰), indicating a dietary shift from a mix of benthic and pelagic prey towards reliance on benthic food items.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0729:AOSITT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We tested bioenergetics model predictions of fish growth and food consumption under feeding regimes that elicited compensatory growth (CG) responses and for control fish fed ad libitum daily. Three treatment groups of seven juvenile hybrid sunfish (F1hybrid of female green sunfishLepomis cyanellus× male bluegillL. macrochirus) received repeating cycles of no feeding and refeeding; fixed no-feed periods of either 2, 4, or 14 d distinguished the treatment groups. The no-feed periods induced CG and were immediately followed by days of ad libitum refeeding. The refeeding periods for each treatment group were continued until the group's mean daily consumption no longer exceeded that of the controls, after which another no-feed period began. Bioenergetics model predictions of cumulative consumption and fish weight in 105-d experiments were not significantly different from observed values in the control group (2–3% model error). However, the model underestimated cumulative consumption (18–25%) and overestimated fish weight (24–37%) in each of the treatment groups. Compensatory growth has considerable potential in aquaculture, and our findings show that bioenergetics models will require modification to account for the effect of feeding history on fish growth and consumption before such models can be used to predict CG responses in aquaculture. The extent to which CG occurs in noncaptive fishes is uncertain, although developing evidence suggests that it may be common. The presence of CG in noncaptive fishes could result in significant errors in model estimates of their food consumption and growth.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0740:TBMUFR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Broodfish of Atlantic salmonSalmo salarwere fed either thiamin-deficient diets fortified with 0.05% and 0.1% amprolium chloride (Amp, a thiamin antagonist) or thiamin-sufficient diets (0% Amp and ASD2-30, a U.S. Fish and Wildlife Service open-formula feed) for 6 months before spawning. We observed Cayuga syndrome (CS) only in the fry produced from broodfish fed the amprolium diets. The percent fry mortality due to CS was less than 1% in the 0.05% Amp group and was more than 3% in the 0.1% Amp group. Free thiamin was the predominant form of thiamin in the eggs of all broodfish; concentrations were two orders of magnitude greater than that of thiamin pyrophosphate (TPP) and thiamin monophosphate (TMP). Free thiamin was greatest in eggs of broodfish fed the thiamin-sufficient diets. Total thiamin and TMP in red blood cells (RBCs) of broodfish fed the thiamin-deficient diets were reduced to the initial levels by the end of the study. Levels of free thiamin in RBCs were similar in all treatment groups at spawning, as were levels of TPP. Amprolium feeding significantly reduced total thiamin levels in heart, liver, and muscle but not in kidney. Except for thiamin found in eggs, TPP was the predominant form of thiamin in all the other tissues, whereas free thiamin was the least predominant. The data support the hypothesis that thiamin deficiency may cause Cayuga syndrome in Atlantic salmon sac fry. The low incidence of the syndrome in this study may be due to the short duration of the feeding trial or to the low levels of amprolium added to the diets.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0747:EODAOT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Egg sampling confirmed that Suwannee River Gulf sturgeonAcipenser oxyrinchus desotoi, a subspecies of Atlantic sturgeonA. o. oxyrinchususe the same spawning site at river kilometer (rkm) 215 from the mouth of the river each year. Forty-nine eggs were recorded in 1995, and 368 were recorded in 1996. Spawning began 4–7 d after the March new moon in both years and lasted 10–11 d; in 1996, a second 10-d spawning round began on the April new moon. Developmental synchrony among eggs recovered suggested several discrete spawning events in both years. Total eggs deposited for three 1996 sampling days was estimated as 405,600–711,000/d, approximating the fecundity range of a large female Gulf sturgeon. Eggs were found only in the southern half of the river, an area with surface currents of 0.5–1.5 m/s and numerous eddies producing reverse bottom currents of 0.1–0.5 m/s. Egg substrate consisted of bedrock limestone thinly overlain by fine sand and densely distributed elliptical gravel 2–10 cm in diameter. Eggs were found predominantly in depths of 2–4 m at water temperatures of 17–21°C, conductivities of 50–100 μS, and dissolved oxygen levels exceeding 5.0 mg/L. The Cody Scarp, 15 rkm above the spawning ground, may mark the upstream limit of spawning areas in the river. Three 2–4-month-old riverine juveniles (82–115 mm total length, TL) collected are the smallest yet captured from any river. Data for 18 riverine age-0 juveniles (to 350 mm TL) suggest that this stage lasts 6–10 months, terminating with migration of fish to the river mouth in January–February. Less than 2% of 461 juveniles captured at the estuarine river mouth (1990–1993) were under 350 mm TL. Riverine age-0 fish were collected over long shallow stretches (typically <4 m deep) of relatively barren sand (rkm 12–238).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0758:ELHSOG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We investigated longitudinal distributions, nearshore movements, and drift of larval native fishes (humpback chubGila cypha, speckled daceRhinichthys osculus, bluehead suckerCatostomus discobolus, and flannelmouth suckerCatostomus latipinnis) in the Little Colorado River, a tributary to the regulated Colorado River in Grand Canyon, Arizona, to determine spawning sites, larval dispersal patterns, and amount of drift into the mainstem Colorado River. Larval distributions and drift indicated native fishes spawned throughout the terminal 14.2 km of the Little Colorado River. In addition, distribution, drift, and trap data suggest an active component to dispersal for all four native species. Drift of larval native fish was greater near shore than midchannel, and except for speckled dace larvae, which were prone to drift at night, larval native fish did not exhibit diel periodicity in drift. During a 46-d period in 1993, we estimated that over 370,000 native fish larvae drifted out of the Little Colorado River into the Colorado River. Regulated discharge from Glen Canyon Dam has all but eliminated spring–summer ponding of tributary mouths that occurred when ascending flows in the Colorado River coincided with descending and base flows in tributaries; thus, drifting larvae are allowed to pass directly into the Colorado River. Survival of larvae now transported into the Colorado River is probably poor because of perennially cold water temperatures and instability of nearshore habitats.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0772:DOLFIA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A comprehensive aging study of vermilion snapper,Rhomboplites aurorubens, was conducted, using 1,465 otoliths collected between 1991 and 1995 from the commercial and headboat fisheries from North Carolina through the Florida Keys. An additional 19 otoliths came from fishery-independent samples from the South Atlantic Bight for fish smaller than 254 mm total length (TL), which is the legal size limit. Marginal increment analysis revealed that rings on the otoliths were deposited annually. This observation is further substantiated by the increasing modal radius of each age ring corresponding to the increasing modal size of the fish at age. Observed ages ranged from age 1 (202 mm mean TL) to age 14 (535 mm TL). The largest fish was 600 mm TL and was estimated to be age 13. The weight–length relationship was described by the equation:W= 9.55 × 10−9(L)3.04, whereW= whole weight in kilograms andL= total length in millimeters. The von Bertalanffy equation was estimated using the inverse, weighted, back-calculated lengths at the last annulus. The equation wasLt= 650 (1−e−0.144(t+0.238)), wheretis age in years.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0787:AAGOVS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Shredded scrap tires were leached in a modified toxicity characteristic leaching procedure (TCLP) extraction method in synthetic saltwater solutions for three sequential 7-d periods. Test salinities were 5, 15, and 25‰. Acute toxicity tests were conducted with larval sheepshead minnowsCyprinodon variegatusand daggerblade grass shrimpPalaemonetes pugio.Mortality decreased following multiple sequential leaching periods. Toxicity decreased with increasing salinity. The fish were more sensitive than the grass shrimp. Dilution series toxicity bioassays were performed with fish and grass shrimp at 5‰ salinity and at 15‰ with fish only. The 96-h LC50s (lethal concentration for half of the test animals) for fish were 10% leachate at 5‰ and 26% at 15‰. The 96-h LC50 for grass shrimp at 5‰ was 63%. The 96-h lowest observed effect concentrations (LOEC) for fish survival were 12.5% at 5‰ and 25% at 15‰. The 96-h LOEC for grass shrimp survival was 50% at 5‰. Growth LOEC values were 12.5% at both salinities for fish and 50% for grass shrimp at 5‰. Chemical analyses revealed no specific components as the cause of observed toxicity. Antagonism between sea salt and toxic chemicals is hypothesized to cause differential toxicity at varying salinities, as opposed to differential solubility of the toxicants. Extrapolation of laboratory results indicates that proposed tire reefs should not pose a serious threat to water quality in Chesapeake Bay. No observed effects concentrations (NOEC) were an order of magnitude or greater above field concentrations calculated from simplified methods. Toxic substances appear to leach from the surface of the tires not from the tire matrix. The use of tires in higher salinity environments appears to pose little direct toxicological risk to resident organisms. However, because unknown toxic chemicals were present in leachates at all test salinities, no assessment can be made regarding persistence, fate, transport, or possible bioaccumulative effects.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1998)127<0796:TOSTLI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor