Early marine life history of juvenile Pacific salmon in two regions of Puget Sound

2005 ◽  
Vol 64 (1) ◽  
pp. 94-107 ◽  
Author(s):  
Elisabeth J. Duffy ◽  
David A. Beauchamp ◽  
Raymond M. Buckley
2016 ◽  
Vol 6 (1) ◽  
pp. 139-152
Author(s):  
Svetlana Naydenko ◽  
Olga Temnykh ◽  
Alexander Figurkin

2016 ◽  
Vol 6 (1) ◽  
pp. 139-152
Author(s):  
Svetlana Naydenko ◽  
Olga Temnykh ◽  
Alexander Figurkin

<em>Abstract.</em>—The Washington Department of Fish and Wildlife and Tribal co-managers are using the Ecosystem Diagnosis and Treatment (EDT) model to identify the spatial and temporal habitat limits of salmon populations and predict the effects of proposed habitat restoration projects for ESA-listed Chinook salmon <em>Oncorhynchus tshawytscha </em>in two Puget Sound watersheds. The collaborative, iterative process focused on habitat-based population models for the Dungeness and Dosewallips watersheds. Workshops were held to develop quantitative characteristics of current, historic, hypothetical properly functioning, and future habitat conditions. The model predicted salmon populations in the watersheds for each set of habitat conditions. Recovery targets were based on the predicted populations for historic and hypothetical properly functioning conditions. Future populations were modeled using projected habitat conditions with individual habitat restoration and protection actions already proposed and combinations of these actions. Populations resulting from further habitat degradation were estimated using the effects of projected human population growth on habitat.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Diego del Villar-Guerra ◽  
Martin H. Larsen ◽  
Henrik Baktoft ◽  
Anders Koed ◽  
Kim Aarestrup

Abstract Spring migrating sea trout juveniles can be classified as parr, pre-smolt or smolt based on body morphology and osmoregulatory capacity. In this respect, parr are assumed to be less prepared for a marine life and to have lower survival at sea than pre-smolts and smolts. However, the behaviour and survival of these trout phenotypes upon entering the sea is not well known. Using passive integrated transponder telemetry, this study found that the return rate from the sea to the natal river was higher for parr compared to pre-smolts and smolts. Additionally, trout classified as parr generally migrated earlier to the sea and a larger proportion returned to the river after less than one year at sea. The daily mortality rate at sea was comparable among the different phenotypes of trout, suggesting that the higher proportion of returning parr to the river was linked to their shorter duration at sea. These results provide evidence of different life-history strategies for seaward-migrating juvenile sea trout, ultimately affecting their return rate to the natal river. Investigations failing to consider downstream migrating parr and pre-smolts risks neglecting a large part of the anadromous population and may result in inaccurate assessments of sea trout stocks in rivers.


<em>Abstract.—</em>Salmon have complex life histories that have been extensively studied, particularly in freshwater, yet most salmon management relies on models that ignore much of salmon life history. For instance, calculation of optimal escapement for most Pacific salmon stocks summarizes their entire life history into a single relationship between spawners and subsequent recruits. Similarly, most analyses of salmon habitat have used models that fail to integrate the complex life history of salmon and have often considered only a single “limiting factor.” Computational methods and models are now being used to incorporate life history and habitat information directly into evaluations of both harvesting and habitat management policies. Challenges and opportunities in using life history models include (1) the need for better dynamic understanding of how habitat affects survival, (2) turning current “expert system” analysis into statistical estimation, (3) application of life history models to hatchery/wild interaction, (4) quantifying essential fish habitat using life history models, (5) using real data and modeling stock structure in evaluation of harvest strategies, and (6) use of such models to explore salmon/ocean interactions.


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