|Document Type:||Journal Article|
|Title:||Estuarine habitat and demographic factors affect juvenile Chinook (Oncorhynchus tshawytscha) growth variability in a large freshwater tidal estuary|
|Author:||Pascale A. L. Goertler, Charles A. Simenstad, Daniel L. Bottom, L Stamatiou, Susan A. Hinton|
|Journal:||Estuaries and Coasts|
|Keywords:||Freshwater tidal estuary,juvenile Chinook salmon,growth,diet,genetic stock of origin|
Estuarine rearing has been shown to enhance within watershed biocomplexity and support growth and survival for juvenile salmon (Oncorhynchus spp.). However, less is known about how growth varies across different types of wetland habitats and what explains this variability in growth. We focused on the estuarine habitat use of Columbia River Chinook salmon (Oncorhynchus tshawytscha), which is listed under the Endangered Species Act. We employed a generalized linear model (GLM) to test three hypotheses: ( 1) juvenile Chinook growth was best explained by temporal factors, (2) habitat, or (3) demographic characteristics, such as stock of origin. This study examined estuarine growth rate, incorporating otolith microstructure, individual assignment to stock of origin, GIS habitat mapping and diet composition along ~130 km of the upper Columbia River estuary. Juvenile Chinook grew on average 0.23 mm/d in the freshwater tidal estuary. When compared to other studies in the basin our growth estimates from the freshwater tidal estuary were similar to estimates in the brackish estuary, but ~4 times slower than those in the plume and upstream reservoirs. However, previous survival studies elucidated a possible tradeoff between growth and survival in the Columbia River basin. Our GLM analysis found that variation in growth was best explained by habitat and an interaction between fork length and month of capture. Juvenile Chinook salmon captured in backwater channel habitats and later in the summer (mid-summer and late summer/fall subyearlings) grew faster than salmon from other habitats and time periods. These findings present a unique example of the complexity of understanding the influences of the many processes that generate variation in growth rate for juvenile anadromous fish inhabiting estuaries.
We examined the growth of juvenile Chinook salmon over a range of wetland habitats along ~130 km of the freshwater tidal Columbia River estuary. We employed a generalized linear model (GLM) to test three hypotheses: (1) juvenile Chinook growth was best explained by temporal factors; (2) estuarine habitat use; or (3) demographic characteristics, such as stock of origin or the timing of seaward migration. We found that variation in growth was best explained by habitat and an interaction between fork length and month of capture. Genetic stock of origin was not an important driver in the variability of estuarine growth rate; possibly divergent stock performance may be homogenized in this system. The size and timing in the estuary is an indication of one juvenile life history transition for Chinook salmon, and in our study estuarine growth rate was more strongly linked to this life history characteristic than genetic groups.
|Notes:||ISSN: 1559-2723 (Print) 1559-2731 (Online)|
|Theme:||Habitats to Support Sustainable Fisheries and Recovered Populations|
Develop effective and efficient habitat restoration and conservation techniques.
Characterize relationships between habitat and ecosystem processes, climate variation, and the viability of organisms.