Salmonid observations at a Klamath River thermal refuge under various hydrological and meteorological conditions

The Beaver Creek confluence with the main‐stem Klamath River was studied to assess salmonid use in a thermal mixing zone under various summer hydrological and meteorological conditions. Main‐stem flow releases from Iron Gate Dam ranged from 17 cms (615 cfs) to 37 cms (1320 cfs) during the study period and main‐stem water temperatures ranged from 19.5 to 26°C. A grid was constructed to define the thermal refuge as a system of cells. Temperatures were monitored using remote temperature loggers and fish counts were conducted using daytime snorkelling. Most juvenile salmonids were observed moving into the refuge when main‐stem temperatures exceeded 22–23°C. Salmonids in the thermal refuge did not necessarily seek the coolest water, but were generally located in habitats commensurate with species‐specific behavioural needs within their thermal tolerance range. Such ranges largely occurred within refuge areas. Variable meteorological conditions confounded observable biological thermal benefit to fish resulting from higher or lower main‐stem flows. Thermal regime dynamics indicated that under the hydrological and meteorological conditions observed, higher flows from Iron Gate Dam showed some ability to change the structure of the refuge area. It appeared that without the thermal refuge, main‐stem flows alone could not sustain the salmonid population because high water temperatures usually exceeded their published thermal tolerance limits. Copyright © 2007 John Wiley & Sons, Ltd.     

Juvenile coho salmon behavioural characteristics in Klamath river summer thermal refugia

During the summer in the main‐stem Klamath River, juvenile salmonids respond positively to cooler tributary temperatures by congregating in large schools at the mouths of these tributaries, referred to as thermal refugia. The purpose of this paper is to summarize results from coho salmon (Oncorhynchus kisutch) thermal refugia studies conducted since 2006 in the Klamath River. Results showed that juvenile coho salmon started using thermal refugia when the Klamath River main‐stem temperature approached approximately 19 °C. The majority of the juvenile coho salmon within the studied thermal refugia were found in the slower velocity habitat associated with cover. Juvenile coho salmon counts in the studied thermal refugia dramatically decreased at temperatures >22–23 °C, suggesting that this approximates their upper thermal tolerance level. Although some juvenile coho salmon were very mobile, others chose, until smoltification, to rear in the mouths and lower reaches of non‐natal tributaries where thermal refugia occurred, apparently because of suitable habitat conditions. Information gained from these investigations will improve our knowledge of the life history of coho salmon in the Klamath River drainage and how they use the main‐stem river. Copyright © 2010 John Wiley & Sons, Ltd.     

The effect of wood and temperature on juvenile coho salmon winter movement,growth, density and survival in side‐channels

In British Columbia, side‐channels have been built to compensate for lost salmonid habitat. Most are structurally simple with little in‐stream wood; however, they support high densities of juvenile coho salmon. We longitudinally divided in halves the top 100 m of two dead‐end artificial side‐channels, one side‐channel with low winter water temperatures (surface‐fed) and one with relatively higher water temperatures (groundwater‐fed), closed the downstream end of each side‐channel with two‐way traps, and treated only one half of each channel with bundles of wood. Trapped fish were marked daily and coho salmon movement, growth and smolt output were monitored for two years. Wood addition increased juvenile coho winter carrying capacity and spring smolt output only in the ‘colder’ surface‐fed side‐channel. In contrast, in the groundwater‐fed side‐channel, with relatively higher water temperatures, the wood treatment slightly reduced the channel's carrying capacity and the spring output of coho salmon smolts. Copyright © 2003 John Wiley & Sons, Ltd.     

Rehabilitation of bedrock stream channels: the effects of boulder weir placement on aquatic habitat and biota

The placement of boulder weirs is a popular method to improve fish habitat, though little is known about the effectiveness of these structures at increasing fish and biota abundance. We examined the effectiveness of boulder weir placement by comparing physical habitat, chemical and biotic metrics in 13 paired treatment (boulder weir placement) and control reaches in seven southwest Oregon watersheds in the summer of 2002 and 2003. Pool area, the number of boulders, total large woody debris (LWD) and LWD forming pools were all significantly higher in treatment than control reaches (p < 0.05). No differences in water chemistry (total N, total P, dissolved organic carbon) or macroinvertebrate metrics (richness, total abundance, benthic index of biotic integrity etc.) were detected. Abundance of juvenile coho salmon (Oncorhynchus kisutch) and trout (O. mykiss and O. clarki) were higher in treatment than control reaches (p < 0.05), while dace (Rhinichthys spp.; p < 0.09) were more abundant in control reaches and no significant difference was detected for young‐of‐year trout (p > 0.20). Both coho salmon and trout response to boulder weir placement were positively correlated with difference in pool area; p < 0.10), while dace and young‐of‐year trout response to boulder weir placement were negatively correlated with difference in LWD (p < 0.05). The placement of boulder weirs appears to be an effective technique for increasing local abundance of species that prefer pools (juvenile coho and trout >100 mm). Based on our results and previous studies on bedrock and incised channels, we suggest that the placement of boulder structures is a useful first step in attempting to restore these types of stream channels. Published in 2006 by John Wiley & Sons, Ltd.     

复合酸辣芥汁银鲑鱼产品的工艺研究

以传统调味技术为基础,对酸辣芥末复合味汁进行工业化设计,确定最佳的实验工艺和配方,开发出适合中国人的饮食习惯及口味的银鲑鱼产品,为冷水鱼的养殖和深加工提供一条可供参考的途径。     

Effect of chill storage under different icing conditions on sensory and physical properties of canned farmed salmon (Oncorhynchus kisutch)

This work focuses the sensory and physical properties of canned farmed coho salmon (Oncorhynchus kisutch); the effect of flake ice and slurry ice as previous slaughter and chilling conditions was studied. Hydrolytic chemical changes related to sensory and physical properties were also evaluated in canned salmon. Thermal treatment led to a canned muscle showing higher firmness, lower cohesivity and colour changes (higher L* and b* values; lower a* values); filling oils showed higher turbidity scores and lower L*, a* and b* values than starting oil. Additionally, oxidised and putrid odour development in canned muscle and filling oil was low. However, previous icing condition and time (up to 9 days) provided no changes in canned muscle and filling oil, except for an increasing oxidised odour and turbidity in filling oil with chilling time. Meantime, free fatty acid formation and K value were markedly affected by previous icing system and time.