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1.
Data on production of fingerling striped bass, Morone saxatilis, in 103 ponds at 17 hatcheries in 1988 were related to information on management practices and water qualities. Production was highly variable, with a median of 50,000/ha. No survival was evident in 12% of ponds; numbers harvested exceeded 250,000/ ha in 5% of ponds. Best survival resulted when larvae were stocked within 2 days after pond filling was started and at hatcheries with relatively low application rates of fertilizers during the prestocking interval. No survival was evident in ponds with pH >9.0 in the week after stocking. High pH's and probably toxic concentrations of un-ionized ammonia were related to water being in ponds for too long prior to stocking and to high applications of fertilizers. Examination of samples of larvae collected at stocking and the week after stocking documented a problem with swim bladder inflation. When larvae were stocked at D5 or D6 (Dl is day of hatch), inflation success averaged 91%: when stocked at ≥D7. inflation success averaged 60%. Measures proposed to improve production include: (1) Stock larvae prior to the critical period of swim bladder inflation(D4-D5). (2) Start filling ponds as close to stocking as is feasible (filling can be completed after stocking). (3) If the concentration of available nitrogen is low, apply no more than 300 µg/L of nitrogen in the prestocking interval. (4) Add phosphorus as needed, but avoid pH>8.5 until larvae are D14.  相似文献   

2.
This volume is a collection of papers that present some strategies and tactics that can be used to improve production and efficiency in the propagation of fingerlings in fertilized hatchery ponds. Species of fish in these papers include: paddlefish, Polyodon spathula; grass carp, Ctenopharygoden idella; silver carp, Hypopthalmichthys molitrix; bighead carp, H. nobilis; walleye, Stizostedion vitreum; saugeye, S. canadense ♀ x S. vitreum ♂ largemouth bass, Micropterus salmoides; striped bass, Morone saxatilis; hybrid striped bass, M. saxatilis ♀ x M. chrysops♂. In addition, there is a paper discussing the culture of penacid shrimp. It is proposed to designate the age of fish as: Dl = the day of hatch; D2 = the next day starting at midnight of D1; etc. It is also proposed to present fertilization amounts of nitrogen (N) and phosphorus (P) as µ/L or mg/L Economic and ecological considerations lead to the recommendation that pond filling should be initiated as close to stocking as feasible and that the pond be filled after stocking. Water quality requirements of larvae vary with developmental stages and species. Excessive fertilization may cause elevated pH and toxic concentrations of unionized ammonia. Best results should be expected from fertilization on a pond-by-pond basis with plant meals or chemical fertilizers applied at appropriate concentrations of available N and P to achieve the desired responses.  相似文献   

3.
Bioassays in static water (mean ± SD; temperature, 20–22 C; pH, 8.2–8.4; alkalinity, 205 ± 10 mg/L CaCO3; total hardness, 220 ± 10 mg/L CaCO3) were used to determine median lethal concentrations (LC50) of un-ionized ammonia (NH3-N) for striped bass Moronc saxatilis and hybrid striped bass M. saxatilis × M. chrysops. The 96 h LC50 for striped bass was 1.01 ± 0.24 mg/L NH3-N3 and was significantly higher than the LC50 for hybrid striped bass (0.64 ± 0.05 mg/L NH3-N). The effects of sublethal ammonia were evaluated after fish were exposed for 96 h to 0.0, 0.25, or 0.5 mg/L NH3-N or to additional exposure to oxygen depleted water (about 2.0 mg O2/L). Plasma ammonia of striped hass did not change as sublethal ammonia increased, but exposure to oxygen depletion caused a decrease in plasma ammonia. In contrast, plasma ammonia of hybrid striped bass increased as environmental ammonia increased, and increased further after exposure to oxygen depletion. Plasma cortisol levels of striped bass were significantly higher and more variable than cortisol levels of hybrid striped bass; additional exposure to oxygen depletion increased this variability, but these responses may be due to the stress of handling and confinement. Mean differences also existed between species for hemoglobin and hematocrit, while differences in variability occurred for osmolality and oxygen depletion rates. Striped bass tolerated ammonia better than hybrid striped bass but were more susceptible than hybrid striped bass to the additional stress of oxygen depletion. Most changes in physiological characteristics were relatively independent of environmental ammonia, but they were affected by oxygen depletion challenge.  相似文献   

4.
吴晗  白俊杰  姜鹏 《海洋渔业》2013,35(1):54-58
水体中氨氮是影响鱼类生存的重要环境胁迫因子。利用静水法测定水体中非离子态氨对转红色荧光蛋白基因唐鱼(Tanichthys albonubes)和野生唐鱼的急性毒性和慢性效应。急性毒性实验结果显示,转基因唐鱼的非离子态氨24、48、72、96 h半数致死浓度(LC50)(2.43、2.12、1.82、1.72 mg·L-1)分别比野生唐鱼相应时间的半数致死浓度(LC50)(2.40、2.10、1.76、1.67 mg·L-1)略高,但无显著性差异;慢性毒性实验结果显示,在不同浓度非离子态氨(0.02、0.18、0.35、0.53、0.70 mg·L-1)胁迫下,转基因唐鱼和野生唐鱼的死亡率无显著差异。研究结果可为评价转红色荧光蛋白基因唐鱼潜在生态风险提供参考依据。  相似文献   

5.
An experiment using differently marked larval striped bass, Morone saxatilis (Walbaum). and its hybrid (M. saxatilis x M. chrysops (Rafinesque)) was performed in two grow-out ponds. Larval striped bass were immersed in oxytetracycline solution to mark their otoliths; hybrids received no treatment. Larvae from both groups were mixed and stocked at 8 days post hatch into the ponds. Striped bass and hybrid larvae grew to a significantly larger size at 35 days in one pond. In both ponds, hybrid lengths at 35 days after hatch were significantly greater than striped bass lengths. However, the magnitude of the size difference between hybrids and striped bass was twofold greater (10%) in one pond than in the other (5%). The proportion of striped bass juveniles at 35 days differed from the initial stocking proportion (0.53) only in one pond, where hybrids showed 12% greater survival than striped bass. Results suggested that the relative survival of hybrids was influenced by growth conditions in the ponds. Based on the ease of protocol and analysis of the marking experiment, we recommend its use to (1) investigate relative performance between genetic groups of young fish in common environments; and (2) predict the effects of introductions of genetically altered fishes.  相似文献   

6.
Immediate and delayed (96 h) mortality, descaling, and injury rates of striped bass Morone sax-atilis and rainbow trout Oncorhynchus mykiss that were inserted into the entrance (suction side) of a Hidrostal pump were compared to those of control fish that were inserted at the exit (pressure side). Comparisons were made in 158-paired trials of striped bass and 86 trials with rainbow trout. The Hidrostal pump had no significant effect on immediate or delayed (96 h) mortality. Immediate mortality for striped bass and rainbow trout averaged 0.1 and 0%, respectively, and delayed mortality averaged 2.9 and 0.1%, respectively. Mean scale loss after passage for striped bass and rainbow trout was low (0.2 and 1.0%, respectively). Frequency of injury to the head, eyes, skin, and tins of pumped striped bass averaged 1.9, 2.8, 1.9, and 18.7%, respectively, and those of rainbow trout averaged 2.3, 0, 2.4, and 3.1%. No significant relationships were detected between fish mortality and pump speed, injected fish density, and debris load. Results suggest that large Hidrostal pumps have the capacity to transport live striped bass and rainbow trout at high density (1-6 fish/L) with little mortality and body injury.  相似文献   

7.
Abstract

Recent interest in the culture of black sea bass, Centropristis striata, has led to questions regarding the environmental requirements of this species for economically-viable production. Here, we present the results of short-term laboratory studies on ammonia toxicity, nitrite toxicity and oxygen consumption rates. Fifty percent of the juveniles died when exposed to 0.7-0.8 mg/L un-ionized ammonia-N for 24 hours (25°C, 23 g/L salinity). All exposed fish survived exposure to ≤ 0.6 mg/L un-ionized ammonia-N for 10 days. Black sea bass juveniles survived 24-hours exposure to 250 mg/L nitrite-N when exposed in 12 or 20 g/L salinity. Fish exposed for 24 hours to nitrite in 35 g/L salinity died when exposed to 250 mg/L nitrite-N, but survived exposure to 100 g/L nitrite-N. All fish exposed to 50 mg/L nitrite-N for 10 days survived (salinities of 12, 20 and 35 g/L). Mean oxygen consumption rate was 0.09 mg/hour/g (25°C). Fish weight significantly affected oxygen consumption rate with larger fish consuming less oxygen per unit time on a weight-specific basis. No treatment effect was observed due to salinity or dissolved oxygen concentration. The information reported here in combination with previous reports provides insight into the environmental requirements of black sea bass culture.  相似文献   

8.
The small‐scale distribution and retention mechanisms of white perch (Morone americana) and striped bass (M. saxatilis) early‐life stages were investigated in the upper Chesapeake Bay estuarine turbidity maximum (ETM). Physical measurements and biological collections were made at fixed‐location stations within the ETM during three research cruises in 1998 and two in 1999. Results were compared with mapping surveys of physical properties and organism distributions above, within, and below the ETM. Physical conditions at the fixed stations differed markedly among cruises and between years due to differences in freshwater flow and wind. In each year, striped bass and white perch larval concentrations were highest in waters of salinity 1–4. Larvae were more abundant in the ETM region in 1998, a high‐flow year, suggesting that the ETM provides favorable nursery habitat when low salinity waters and the ETM coincide in high freshwater‐flow conditions. In 1998, the earliest pelagic life stages of fish larvae (eggs, yolk‐sac larvae) and the copepod Eurytemora affinis, an important prey of feeding larvae, apparently were retained in deep, landward‐flowing water within the salt front and ETM region. Statistical analyses indicated that distributions of white perch and striped bass post‐yolk‐sac larvae were associated with E. affinis distributions and suggested that retention of larval fish could result from tracking prey. Comparing fixed‐station and mapping approaches demonstrates the importance of sampling at different spatial scales within the ETM region and suggests that larvae are faced with trade‐offs between selecting zones of high retention or high visual‐feeding success.  相似文献   

9.
The emergence of a new sublineage of viral hemorrhagic septicemia virus (VHSV) within the Laurentian Great Lakes has caused concern for aquaculture in the United States. Because of the occurrence of VHSV in a new geographic location, new host species have been identified and the complete host range has not been determined. This study confirmed the high resistance of rainbow trout, Oncorhynchus mykiss, to VHSV type IVb infection. In addition, the experimental susceptibility of hybrid striped bass, Morone chrysops ♂ × Morone saxatilis ♀, to VHSV type IVb infection was examined but determined to be highly dependent on age of fish and exposure temperature. No mortality was observed in adult fish infected via intraperitoneal (IP) injection at 15 C, whereas yearling fish infected via IP injection under the same conditions experienced 20.8% mortality. Among yearling fish infected via IP injection, mortality increased to 100% when exposure to VHSV occurred at 10 C. An LD50 for yearling hybrid striped bass exposed to VHSV at 10 C by IP injection was determined to be 1.4 × 104 pfu (SE = 2.1). Thus, at 10 C, yearling hybrid striped bass experience a high mortality when exposed to VHSV IVb by IP injection.  相似文献   

10.
Catch‐and‐release fishing has increased in many fisheries, but its contribution to fishing mortality is rarely estimated. This study estimated catch and release mortality rates of striped bass, Morone saxatilis (Walbaum), for the spring recreational fishery in the Hudson River. Treatment fish (caught with live bait on spinning gear) and control fish (captured by electric fishing) were placed in in situ holding pens for 5 days. Mortality rates were estimated using conditional instantaneous mortality rates and additive finite mortality rates. Influences of variables (playing and handling time, hook location, degree of bleeding and fish length) on hooking mortality rates were examined by logistic regression. Conditional instantaneous mortality rates and additive finite mortality rates were 31 and 28%, respectively. Hook location significantly affected the survival of striped bass. Angling catch, effort, and release rates must be integrated with associated hooking mortality rates before this component of overall population mortality can be incorporated into management decisions.  相似文献   

11.
It has been reported that metabolic rates of striped bass Morone saxatilis and hybrid striped bass M. chrysops♀ x M. saxatilis♂ are different. A series of experiments were conducted to further characterize oxygen consumption and metabolism of striped bass and its hybrid, the sunshine bass. Oxygen consumption was measured to determine standard and routine metabolic rates of striped bass and hybrid striped bass in a freshwater, flow‐through tank system. Additionally, blood chemistry stress indicators of the two bass groups were compared in both fresh and brackish water. Hematocrit (% PCV) and hemoglobin were measured in order to compare oxidative efficiencies of the bass. Plasma glucose, chlorides, and cortisol levels were measured to compare the relative stress status of the two bass types reared under experimental conditions. No significant differences were found in average daily oxygen consumption between striped bass and sunshine bass for either standard metabolism (P= 0.92), or routine metabolism (P = 0.86). Standard metabolic rates of oxygen consumption were 69 ± 4.1 and 68 ± 3.5 mg 02/kg3/4 bw/h for sunshine bass and striped bass respectively. Routine metabolic rates were 132 ± 30 and 125 ± 30 mg O2/kg3/4 bw/h for sunshine bass and striped bass respectively. While there were no significant differences in oxygen consumption between species, normal feeding activity generally resulted in increased oxygen consumption by the fish. Striped bass had significantly lower hematocrit values (P= 0.0001), but significantly higher hemoglobin concentrations than sunshine bass maintained in freshwater (P= 0.0001). Striped bass had significantly higher (P= 0.0001) levels of plasma glucose compared to sunshine bass (176 ± 8.6 vs. 103 ± 5.6 mg/dL respectively). Plasma chloride levels for striped bass (123 ± 1.9 mEq/L) were significantly higher (P= 0.041) than plasma chloride levels of sunshine bass (117 ± 1.7 mEq/L). Plasma cortisol levels were significantly higher (P= 0.0081) for striped bass (147 ± 8.4 ng/mL) compared to sunshine bass (119 ± 5.6 ng/ mL) when reared in freshwater. When maintained in brackish water, sunshine bass had significantly higher hematocrit values (P= 0.0001), and hemoglobin concentrations (P= 0.0012) when compared to striped bass. However, sunshine bass had significantly higher hemoglobin concentrations (P= 0.0012) when compared to striped bass. In addition, plasma glucose levels were significantly lower (P = 0.0079) for sunshine bass (79 ± 4.1 g/dL) when compared to striped bass (115 ± 11 g/dL). There were no significant differences between the bass in levels of chlorides or cortisol. No differences were detected in oxygen consumption. However, hybrid striped bass may have more efficient oxidative metabolism due to elevated hemoglobin concentrations. While striped bass hemoglobin values tended to be higher in brackish water than in freshwater, sunshine bass hematocrit or hemoglobin values generally were significantly higher than striped bass in both fresh and brackish water. Based on these results, hybrid striped bass may be capable of directing more energy towards growth than striped bass due to more efficient oxidative metabolism and lower losses of energy related to increased stress.  相似文献   

12.
Acceptance and Consumption of Food by Striped Bass and Hybrid Larvae   总被引：1，自引：0，他引：1  
Food acceptance, consumption and weaning times were investigated for striped bass ( Morone saxatilis ) and hybrid striped bass ( M. saxatilis × M. chrysops ) larvae. Experimental treatments consisted of: control groups of striped bass (SC) and hybrids (HC) fed Artemia nauplii; hybrids fed formula food (HF); and hybrids weaned from Artemia nauplii to formula food at 11–15 days (HF1), and 18–22 days (HF2) posthatch. The formula diet did not support growth and resulted in total mortality of the HF hybrids by the third week posthatch. HF1 fish had significantly slower growth and lower survival than HF2 of HC. The HF2, HC and SC groups had similar growth and survival, which indicated no heterosis in hybrids. There were no differences in Artemia nauplii consumption by the SC and HC groups. Daily consumption increased exponentially for both groups (0.8 to 50–60 cal/day/larva between 7 and 30 days posthatch). Weight specific consumption (WSC) decreased initially and then increased for both groups. A mean WSC of 58% (range of 24–83%) was found for the combined SC and HC groups. Food conversion ratio, growth efficiency, caloric efficiency, and productive protein values were similar for striped bass and hybrid larvae.  相似文献   

13.
The effects of feeding different sources of brine shrimp nauplii with different fatty acid compositions on growth, survival, and fatty acid composition of striped bass, Morone saxarilis and palmetto bass (M. saxatilis x M. chrysops) were determined. The sources of brine shrimp were Chinese (CH), with a high percentage of 20:5(n-3), eicosapentaenoic acid (EPA), and Colombian (COL), San Francisco Bay (SFB), and Great Salt Lake (GSL), with low percentages of EPA but high percentages of 18:3(n-3), linoienic acid. None of the brine shrimp sources contained a measurable amount of 22:6(n-3), docosahexaenoic acid (DHA). After enrichment with menhaden oil to increase the content of EPA and DHA, the GSL brine shrimp nauplii were also fed to hybrid striped bass.Growth and survival of fish larvae fed brine shrimp nauplii with high percentages of EPA and DHA (CH and GSLE) were higher (P < 0.05) than those of fish fed brine shrimp with a low percentage of EPA (COL, SFB, and GSL). The ratio of 20:3(n-9) eicosatrienoic acid (ETA), to DHA in polar lipids (phospholipids) of fish, traditionally used as an indicator of essential fatty acid (EFA) sufficiency of the diet, was not a reliable indicator of essential fatty acid sufficiency of diets for larval striped bass and hybrid striped bass. However, the ratio of ETA to EPA appears to be an appropriate indicator. An ETA-to-EPA ratio in phospholipids of less than 0.10 is consistent with an EFA sufficient diet.  相似文献   

14.
The diet of Chesapeake Bay striped bass in the late 1950s   总被引：1，自引：0，他引：1  
The diet of Chesapeake Bay striped bass, (Morone saxatilis) Walbaum, based on unpublished stomach content data from 916 fish collected between 1955 and 1959 was described. The diet in the late 1950s, quantified using an index of relative importance (IRI), was dominated by Atlantic menhaden, Brevoortia tyrannus Latrobe. Atlantic menhaden (66%) and bay anchovy, Anchoa mitchilli Valenciennes, (19%) had the highest IRI value overall. Small striped bass (<600 mm total length) ate predominantly bay anchovy (IRI = 67%). Large striped bass (≥ 600 mm total length) ate predominantly Atlantic menhaden (IRI = 93%). Since 1990 small striped bass rely more on invertebrate prey and larger fish now rely more on small pelagic prey, such as bay anchovy and 0‐age clupeids. Analysis of historical data using current techniques provided a valuable tool for comparison to help in understanding the current striped bass predator–prey relationship in Chesapeake Bay.  相似文献   

15.
Trophic dynamics and conceptual niche spaces of top piscivores were assessed using stable isotope analysis following the introduction of hybrid striped bass Morone saxatilis (Walbaum) × Morone chrysops (Rafinesque) into an established reservoir fishery devoid of gizzard shad, Dorosoma cepedianum (Lasueur). Hybrid striped bass were initially stocked into Three Mile Lake, Iowa as an attempt to biologically control pervasive yellow bass, Morone mississippiensis Jordan & Eigenmann, populations. From the analyses, it concluded that hybrid striped bass predominately targeted prey fish located in the littoral habitats of the reservoir and did not selectively consume yellow bass as intended. Bayesian isotope mixing models described the diets of hybrid striped bass to include a variety of prey fish, predominantly consisting of young bluegill Lepomis macrochirus and yellow bass. Food resource overlap among hybrid striped bass, largemouth bass, Micropterus salmoides Lacépède, and walleye, Sander vitreus (Mitchill), appeared substantial based on the isotopic niche overlap model. Results from this case study, in conjunction with the hindsight that yellow bass populations became prolific even with stockings of hybrid striped bass, suggest that their use to control yellow bass populations may not be a viable management strategy in southern Iowa.  相似文献   

16.
The recent increase in the Atlantic coast population of striped bass, Morone saxatilis (Walbaum), prompted managers to re‐evaluate their predatory impact. Published and unpublished diet data for striped bass on the Atlantic Coast of North America were examined for geographical, ontogenetic and seasonal patterns in the diet and to assess diet for this species. Diets of young‐of‐the‐year (YOY) striped bass were similar across the Upper Atlantic (UPATL), Chesapeake and Delaware Bays (CBDEL) and North Carolina (NCARO) areas of the Atlantic coast where either fish or mysid shrimp dominate the diet. For age one and older striped bass, cluster analysis partitioned diets based on predominance of either Atlantic menhaden, Brevoortia tyrannus (Latrobe), characteristic of striped bass from the CBDEL and NCARO regions, or non‐menhaden fishes or invertebrates, characteristic of fish from the UPATL, in the diet. The predominance of invertebrates in the diets of striped bass in the UPATL region can be attributed to the absence of several important species groups in Northern waters, particularly sciaenid fishes, and to the sporadic occurrences of Atlantic menhaden to UPATL waters. In all regions, across most seasons and in most size classes of striped bass, the clupeiod fishes; menhaden, anchovies (Anchoa spp.) and river herrings (Alosa spp,) and Atlantic herring, Clupea harengus L., dominated the diets of striped bass above the first year of life.  相似文献   

17.
The efficacy of short-term feed withdrawal as a method of reducing ammonia concentrations in catfish production ponds was investigated. Channel catfish, Ictalurus punctatus, fingerlings averaging 35 g were stocked at 9,880 fish/ha into six 0.04-ha ponds and fed twice daily to satiation for 131 days. For a 9-day period immediately prior to harvest (days 132-140), feeding of fish in three ponds was terminated, while feeding of fish in three other ponds was continued. Total ammonia-nitrogen concentrations were not significantly reduced (P > 0.05) in unfed ponds until 9 days after feeding was terminated. However, after 7 days without feed, un-ionized ammonia concentrations were significantly higher (P < 0.05) in ponds where fish were not fed, due to significantly higher (P < 0.05) pH levels. Short-term (9 days) feed withdrawal had little effect on lowering total ammonia and actually increased concentrations of toxic un-ionized ammonia in ponds.  相似文献   

18.
Several species of bacteria have been isolated from diseased striped bass, Morone saxatilis (Walbaum), in Chesapeake Bay. Mycobacteria species are of particular interest because of their association with chronic lesions in both fish and humans. The resulting disease in fish may be characterised by emaciation, inflammation of the skin, exophthalmia (pop‐eye), ascites (dropsy), open lesions, and ulceration. The prevalence of mycobacterial infection in 217 striped bass in the Maryland portion of Chesapeake Bay was determined to provide evidence of decreased overall condition of fish affected by these bacteria. The density of the granulomas was higher in the spleen and head kidney than either the heart or liver, and appeared to be most closely associated with the presence of an external lesion. Thirty‐eight per cent of the fish showed some sign of an external lesion. Granulomas appeared in at least one organ in 53% of the fish sampled regardless of the presence or absence of an external skin lesion. Condition factor was significantly higher for striped bass without external lesions (0.96) than those with lesions (0.82). Striped bass with no internal granulomas and no external lesion had the highest condition factor (0.99) and fish with granulomas and external lesions the lowest (0.81). Slopes of the regression loge weight (g) and loge length (mm) for striped bass with external lesions was significantly higher than those fish without external lesions and had a lower r2. The results suggest that striped bass that are infected with mycobacteria have decreased overall health.  相似文献   

19.
Whole-animal thyroxine (T4) and 3,5,3′-triiodothyronine (T3) levels were measured in larval and juvenile striped bass, Morone saxatilis, reared for 10 days at one of three levels of salinity (equivalent to fresh water (FW), one-third seawater (1/3 SW), and seawater (SW) and two temperatures (15°C and 20°C). The striped bass were pre-metamorphic larvae, metamorphic larvae or juveniles. The short-term effects of seawater on plasma T4 levels of juvenile striped bass were also measured. Higher salinities increased T4 levels in premetamorphic larvae. In metamorphic larvae, SW and 1/3 SW increased T4 levels and SW increased T3 levels at 20°C. This response was eliminated in those at 15°C. Whole-animal thyroid hormone content was unaffected by salinity or temperature in juvenile striped bass, although significant fluctuations in plasma T4 levels occurred in those transferred to 1/3 SW and SW. The thyroid axis of striped bass responds to salinity and temperature as early as in the pre-metamorphic stage. Thyroid hormones may mediate the beneficial effects of salinity on larval striped bass growth and survival.  相似文献   

20.
Between 1997 and 2000, an outbreak of skin lesions and observations of emaciated striped bass, Morone saxatilis (Walbaum), in upper Chesapeake Bay were attributed to a perceived shortage of its main prey, Atlantic menhaden, Brevoortia tyrannus Latrobe. Abundance estimates, Atlantic menhaden consumption per recruit analysis (modified yield‐per‐recruit), bioenergetics analysis and predator–prey theory were combined to explore whether an imbalance between striped bass and Atlantic menhaden in upper Chesapeake Bay was plausible. Reduced fishing mortality and higher size limits that underpinned the effort to restore striped bass during the 1980s and 1990s lead to more abundant and larger striped bass in upper Chesapeake Bay, increasing predatory demand for forage‐sized Atlantic menhaden, the abundance of which declined to a historic low. Nominal losses of age 0–2 Atlantic menhaden to harvest and potential striped bass predation exceeded supply after 1998. The outbreak of lesions in upper Chesapeake Bay striped bass coincided with increased variation in weight‐at‐length, decreased length‐at‐age, and decreased presence of Atlantic menhaden in diets. Decreased attack success, inferred from a 97% decline in ratios of forage‐sized Atlantic menhaden to striped bass between 1983 and 1998, would have expected to have been followed by a deterioration of striped bass nutritional state. Transmission of disease would have been aided by high density of striped bass in poor nutritional condition residing in degraded habitat (Chesapeake Bay was the most hypoxic estuary in the mid‐Atlantic region in the late 1990s). These problems suggest that striped bass exceeded their carrying capacity in Chesapeake Bay during the late 1990s.  相似文献   

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