摘要:

Weight and length data collected during the summers from 1984 through 1994 were used to examine the seasonal life history strategy of Arctic ciscoesCoregonus autumnaliscollected from Prudhoe Bay, Alaska. Differences in observed and predicted weight were used to determine if condition increases during the summer feeding season when energy reserves are accumulated and decreases during winter when energy reserves are depleted. Data from proximate body analyses of lipid and protein content collected from 1991 to 1993 also were examined. Condition was indexed as residual values generated from a whole population least-squares regression of loge-transformed weight and length data. For data pooled by individual year-classes, we tested the conceptual hypothesis that mean residual value, mean lipid content, and mean protein content increased during summer and decreased during winter. For the 12 year-classes examined, concurrent mean residual values supported our conceptual hypothesis in 61 of 76 instances (P< 3.0 E-7), but for mean lipid content and mean protein content, our hypothesis was supported in only 13 of 21 cases (P= 0.14) and had to be rejected. However, 6 of the 8 failures in lipid change and 7 of 13 failures in residual change were associated with summer 1991. Data suggested that Arctic ciscoes did not accumulate lipid reserves during summer 1991 and that relative condition analysis detected this anomaly in nearly every year-class examined. Results were therefore consistent with a strategy of accumulating energy reserves in summer and depleting those reserves to survive the Arctic winter.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1996)125<0600:IAIVIT>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Tropical streams on high oceanic islands are characterized by populations of amphidromous gobioid fishes. Adult fish live and breed in freshwater and many spawn at high (>300 m) elevations. Newly hatched fry are swept down to the sea where they develop for a period of time before recruiting to a stream. In analogous habitats in other geographic areas, amphidromous populations have further evolved into landlocked forms (i.e., populations that spend their entire life cycle in freshwater). We analyzed depositional patterns of trace elements in the otoliths of adultLentipes concolor, an amphidromous goby endemic to Hawaii, to determine whether landlocked forms occurred. Otoliths were obtained from fish collected from the Hawaiian stream habitats most likely to harbor landlocked populations—upper elevations of interrupted streams and sections of streams above high waterfalls. A transition from a marine phase to freshwater existence was demonstrated as a decrease from high to low strontium : calcium ratios in the otolith with increasing distance from the otolith's core. In every case, otoliths from these gobies showed evidence of a marine planktonic larval stage, suggesting that even in habitats physically isolated from the sea, these freshwater fish require a marine larval phase.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1996)125<0613:EOAMLS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We used daily air and water temperatures from 14 lakes in Ontario to develop and test a simple method for constructing lake-specific empirical models for predicting daily littoral water temperatures. Data requirements for prediction are modest (average air temperature, day of the year) and the method is robust and practical, requiring only a few (15–20) well-spaced water temperature observations to construct a single-year model that can generate reasonably accurate predictions for an entire ice-free season. The ability of a singe-lake model to predict several years of temperature data is significantly improved by explicitly including information on ice-out date in the model. Our multiyear model for Lake Opeongo described most (18 of 22) years well. Years that were not well described were usually coincident with El Nino Southern Oscillation events. Used with caution, the method can be an effective tool for supplementing direct monitoring of littoral water temperatures and for generating historical water temperature estimates when direct estimates are lacking. These capabilities should be of particular use to fisheries biologists studying or managing populations of fish species with critical life stages that are affected by littoral water temperatures.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1996)125<0622:NAEMFT>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The distribution of juvenile bull troutSalvelinus confluentuswas observed on three nights (0000–0200 hours) during July 24–28, 1992, in a large plunge pool in Granite Creek, a direct tributary to Lake Pend Oreille in northern Idaho. The pool contained a strong side-to-side thermal gradient (8–15°C) created by the confluence of Granite Creek (water temperature 15°C) with Sullivan Springs, a much colder (8°C) stream of comparable discharge. Juvenile bull trout chose the coldest water available (8–9°C). Distribution of bull trout within the plunge pool could not be attributed to differences in water depth, substrate, velocity, overhanging cover, or interactions with other fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1996)125<0628:DOJBTI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659-125.4.631

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor