Variability in the performance of juvenile Chinook salmon is explained primarily by when and where they resided in estuarine habitats

Estuarine habitats provide rearing opportunities for the juvenile life stage of anadromous fishes. Because survival is positively correlated with juvenile performance, these estuarine habitats play an important role in population abundance and productivity. To provide information for the recovery of several depressed stocks of Chinook salmon in the Columbia River Basin, we sought to identify the factors that explain variability in performance. Using otolith‐derived estimates of juvenile somatic growth rate as an index of recent performance, we observed a negative nonlinear relationship between growth rate and day of year, and a decreasing and increasing trend of growth rate over the 8 years of this study and distance from the river mouth respectively. Using a generalised linear modelling approach, we found that variability in juvenile somatic growth rate was best explained by where and when individuals were collected, their body size, contaminant loads, stock of origin, and whether a fish was hatchery produced or unmarked. Lastly, we argue that a considerable improvement to the growth rate of juveniles in estuarine habitats is physiologically possible. The results of this 8‐year study provide a baseline of the performance of juvenile Chinook salmon to evaluate habitat restoration programs and to compare against future anthropogenic conditions.     

Spatiotemporal patterns of mountain whitefish (Prosopium williamsoni) in response to a restoration of longitudinal connectivity

To examine the role of longitudinal connectivity on the spatial and temporal dynamics of mountain whitefish (Prosopium williamsoni), we quantified movement and population dynamics following installation of the Landsburg Dam fishway, Cedar River, WA, USA. Mountain whitefish is widely distributed, poorly studied and not the focus of restoration. Before the fishway, mountain whitefish were not observed above the dam. Here, we focus on snorkel counts collected at reach and mesohabitat (e.g. pools) scales over 11 summers on the 20‐km above‐dam segment following restoration. A camera within the ladder provided number, size and movement timing, thereby informing on behaviour and recolonisation. Segment‐scale abundance increased following fish passage reaching an asymptote in 7 years, and mountain whitefish were detected throughout the main stem in 10 years. Annual movement through the ladder increased over time and was positively correlated with instream abundance and discharge, but negatively correlated with water temperature. About 60% of fish movements occurred in spring and early summer, potentially for foraging opportunities. Reach‐scale abundance peaked between 7 and 10 km from the dam; deep, cool (~10.6 to 11.6°C) conditions characterised these reaches. At the mesohabitat scale, mountain whitefish detection increased with depth and velocity after accounting for distance from the dam. Our results show how restoring longitudinal connectivity allowed this nontarget species to colonise newly available habitat. Their response supports the critical roles of longitudinal connectivity and environmental conditions, that manifest at different spatial scales, in dictating how freshwater fish respond to habitat disturbance.     

猪断奶后多系统消耗性综合征及猪皮炎肾病综合征的防制措施

猪的猪断奶后多系统消耗性综合征(PMWS)及猪皮炎肾病综合征(PDVS)是两种衰弱性疾病.到目前为止治疗这两种疾病的努力均告失败.显然,卫生和管理是当前有助于控制这两种疾病的唯一措施.     

Induced Maturation and Spawning of the Chinese Catfish Clarias fuscus

Chinese catfish ( Clarias fuscus ) were successfully spawned in Hawaii using human chorionic gonadotropin (HCG) at dosage rates of two and four international units (IU) per gram body weight. Fish not injected with HCG did not produce viable eggs. Successful spawns with HCG occurred between May and October. Hatch rates of up to 80% were obtained during June, July, and August for those fish given either a 2 or 4 IU per gram body weight injection of HCG. Fish spawned in either May or October yielded significantly higher hatch rates when injected with 4 rather than 2 IU per gram body weight. Fish held at elevated temperatures (28 to 30 C) prior to the normal spawning season developed significantly larger oocyte diameters, 60 days earlier than fish held under ambient temperature conditions (21.5 to 24 C). Photoperiod manipulation at ambient temperature conditions was associated with earlier oocyte maturation, but photoperiod effects were much less important than temperature.     

Evaluation of Corn Gluten Feed as a Dietary Ingredient for Pond-Raised Channel Catfish Ictalurus punctatus

Abstract.— This study was conducted to evaluate corn gluten feed as an alternative feedstuff in the diet of pond-raised channel catfish Ictalurus punctatus . Three 32%-protein diets containing 0%, 25%, or 50% corn gluten feed were tested. Channel catfish fingerlings (average weight: 57 g/fish) were stocked into 15 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed to satiation once daily for a 147-d growing period. No differences were observed in feed consumption, weight gain, feed conversion ratio, survival, or fillet protein concentration among fish fed the test diets. Fish fed diets containing 25% and 50% corn gluten feed exhibited a lower level of visceral fat and a higher carcass yield than fish fed the control diet without corn gluten feed. The diet containing 50% corn gluten feed resulted in a lower level of fillet fat and a higher level of moisture than the control diet. There were no visible differences in the coloration of skin or fillet of channel catfish fed diets with and without corn gluten feed. Results from this study indicated that channel catfish can efficiently utilize corn gluten feed at levels up to 50%n without adverse effect on feed palatability, weight gain, or feed efficiency. Corn gluten feed may be beneficial in reducing fattiness of channel catfish and improving carcass yield by reducing the digestible energy to protein ratio of the diet.     

0–7–21 Radiation Therapy for the Treatment of Canine Oral Melanoma

Eighteen dogs with malignant melanoma of the oral cavity were treated with high-dose per fraction (0–7–21) radiation therapy. Eight hundred cGy was administered on days 0, 7, and 21 for a total dose of 2,400 cGy in 3 weeks. Of 17 dogs evaluated, 9 (53%) had a complete remission and 5 (30%) achieved a partial remission with an overall response rate of 83%. Local failure occurred in 2 of the 9 dogs where a complete response was initially observed. One dog died of intercurrent disease, and one died of metastatic disease without evidence of local recurrence. Five dogs are alive and free of disease 9 to nineteen months from the initiation of therapy. The 0–7–21 protocol was well-tolerated, and acute radiation reactions were low-grade and limited to the skin. The results of this study demonstrate that oral melanomas in dogs are responsive to radiation. 0–7–21 radiation therapy offers a viable alternative to radical excision, especially when tumor volume or location would require cosmetically or functionally debilitating surgery.     

COLLAGENASE CHEMONUCLEOLYSIS—A LONG TERM RADIOGRAPHIC STUDY IN NORMAL DOGS

Five clinically normal five year old dogs were used in this study. From a randomised table inter ver tebral discs were each injected with either collagenase or calcium chloride diluent. The surgically exposed cervical discs were injected with 50 units whereas thoracic and lumbar discs were injected under fluoroscopic guidance with 100 units of the enzyme. Postinjection radiographs revealed significant (p ≤ .05) disc space narrowing in enzyme injected discs. The cervical discs had the highest frequency of radiographic narrowing (87%) followed by the thoracic (70%) and lumbar (53%) discs. Spondylosis deformans developed at the sites of cervical enzyme injections. None of the dogs had neurologic abnormalities one year postinjection.     

Particle Size Distribution in Two Lipid Emulsions Used for the Enrichment of Artemia nauplii as a Function of Their Preparation Method and Storage Time

The present study examined the distribution of particle sizes in two experimental standardized lipid emulsions (distributed by ICES, International Council for the Exploration of the Sea) as a function of the preparation method (hand shaking or ultrasonic blending) and as a function of storage time. A 24-h enrichment trial compared the incorporated HUFA levels in the nauplii of Artemia franciscana .
The emulsion droplets in the 50% HUFA emulsion (ICES 50, ethyl ester based) were much smaller than in the 30% HUFA emulsion (ICES 30, triacylglycerol-based) in which 90% of the droplets had a diameter below 12.3 μm as compared to 1.3 pn in ICES 50. The blending method highly affected particle sizes. High-shear blending instead of the classical hand shaking of the emulsion of both ICES 30 and 50 reduced the mean particle size from 5.06 to 1.07 μm and from 0.38 to 0.11 μm, respectively. The particle size distributions remained stable during the 1-wk storage, suggesting the absence of agglomeration or bacterial development. The fatty acid composition of 24-h enriched Artemia reflected differences in the HUFA profile of the emulsions, but was independent of observed differences in the size of the particles.