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Although the importance of diversity to maintaining metapopulation stability is widely recognized, the ecological characteristics that lead to synchronous dynamics within population aggregates are often unclear. We used a constrained dynamic factor analysis to explore patterns of covariance in productivity among 16 Fraser River sockeye salmon (Oncorhynchus nerka) conservation units (CUs). Specifically, we tested whether coherent trends in productivity covaried with five distinct ecological attributes: physical characteristics of nursery lakes, large-scale management interventions, genetic similarity, adult migration phenology, or juvenile migratory traits. The top-ranked model had two trends based on nursery lake characteristics and juvenile migratory traits. One trend represented the dynamics of CUs that rear in nursery lakes prior to ocean entry and undergo relatively rapid marine migrations. The second included a sea-type CU, Harrison River, which enters the marine environment without rearing in a nursery lake and migrates more slowly. The uniform response of lake-type CUs, as well as Harrison River CU's unique life history, suggests that coherent trends are structured by traits that covary with broad life history type, rather than fine-scale characteristics. Furthermore, we document substantial temporal variability in the strength of synchronous dynamics among Fraser River CUs. Greater synchrony in recent years suggests that the importance of shared regional drivers, relative to local processes, may have increased. S'il est generalement reconnu que la diversite est importante pour le maintien de la stabilite des metapopulations, les caracteristiques ecologiques qui menent a une dynamique synchrone au sein de groupes de populations demeurent souvent mal comprises. Nous avons utilise l'analyse des facteurs dynamiques avec contraintes pour examiner les motifs de covariance de la productivite entre 16 unites de conservation (UC) de saumons sockeyes (Oncorhynchus nerka) du fleuve Fraser. Nous avons plus particulierement verifie s'il y a covariance entre des tendances coherentes de la productivite et cinq attributs ecologiques distincts, a savoir : les caracteristiques physiques du lac de sejour, les interventions de gestion a grande echelle, la similitude genetique, la phenologie de la migration des adultes et les caracteres migratoires des juveniles. Le modele le mieux cote comptait deux tendances basees sur les caracteristiques du lac de sejour et les caracteres migratoires des juveniles. Une tendance representait la dynamique d'UC elevees dans des lacs de sejour avant l'entree en mer et caracterisees par des migrations marines relativement rapides. La seconde comprenait une UC de type marin, de la riviere Harrison, qui entre dans le milieu marin sans elevage dans un lac de sejour et migre plus lentement. La reaction uniforme des UC de type lacustre ainsi que le cycle biologique singulier de l'UC de la riviere Harrison donnent a penser que les tendances coherentes sont structurees par des caracteres qui presentent une covariance avec le type de cycle biologique general, plutot qu'avec des caracteristiques a echelle fine. Nous documentons en outre une variabilite temporelle considerable de la force de la dynamique synchrone entre les UC du fleuve Fraser. Un plus grand synchronisme ces dernieres annees indiquerait que l'importance de facteurs regionaux communs pourrait avoir augmente par rapport a celle de processus locaux. [Traduit par la Redaction], Introduction Diversity tends to stabilize systems across ecological scales (McCann 2000). For example, asynchronous dynamics among multiple subpopulations can reduce the temporal variability of metapopulations (Schindler et al. 2010). As [...]

Objective: To examine the relationship between family meals and nutrition behaviors of adolescents. Design: Secondary analysis of Youth'07, a nationally representative survey. Setting: Secondary schools in New Zealand. Participants: Randomly selected adolescents (aged 13-17 years, n = 9,107) completed a multimedia and anonymous survey about their health. Variables Measured: Body mass index and eating behaviors. Analysis: Multiple logistic regression equations were used to determine the associations between family meals and body size and dietary behaviors, controlling for demographic variables. Results: Nearly 60% of young people shared a meal with their families 5 or more times in the previous week. Frequent family meals were associated with greater consumption of fruits and vegetables (P less than 0.001), and breakfast (P less than 0.001). Adolescents who frequently shared family meals were also more likely to report that what they ate in the past week was healthy than adolescents who did not (P less than 0.001). There was no relationship between frequency of family meals and body mass index (P = 0.60). Conclusions and Implications: Data from the current study suggest that family meals cannot be used as a single strategy for obesity prevention, but they may provide an important opportunity for young people to consume healthy food. (Contains 3 tables.)

The revised Fisheries Act requires that Limit Reference Points (LRPs) be identifed for all major fsh stocks. For Pacifc salmon, major fsh stocks are represented by stock management units (SMUs). An SMU is composed of one or more salmon conservation units (CUs), which are the assessment units under the Wild Salmon Policy, WSP. We introduce methods to estimate LRPs at the SMU level that integrate statuses derived under the WSP at the CU level. We demonstrate and evaluate the LRPs for three case study SMUs: Interior Fraser Coho (Oncorhynchus kisutch), West Coast Vancouver Island (WCVI) Chinook (O. tshawytscha), and Inside South Coast Chum (O. keta) - excluding Fraser River. Methods are divided into two categories: CU status-based LRPs and aggregate abundance LRPs. CU status-based LRPs are recommended as the default method, and are based on the proportion of CUs above levels associated with increased risk of extinction (above 'Red' status) under the WSP. Aggregate abundance methods may be used supplementally to meet specifc fsheries management requirements. Aggregate abundance LRPs are subdivided into logistic regression LRPs and projection LRPs. Both types of aggregate abundance LRPs are defned at the SMU-level abundances associated with a desired probabilty of all component CUs being above Red status, but they differ in that logistic regression LRPs are determined directly from historical data while projection LRPs are determined from projections of CU-level population dynamics. We discuss suitability and requirements for the application of the various LRP estimation methods, drawing from the range of data and information availability among the case studies. In general, the application of aggregate abundance LRPs may be limited to SMUs where the CU-level populations covary, as demonstrated for the Interior Fraser Coho case study, and where covariance has not changed over time or, for projection LRPs, those changes can be parameterized. [ABSTRACT FROM AUTHOR]

Limit reference points, LRPs, defne the stock status below which serious harm is expected to occur to a stock. LRPs are required for major fsh stocks, or Stock Management Units (SMUs) that are prescribed by regulation under amendments to the Canadian Fisheries Act (2019). Pacifc salmon are unique among marine fsh stocks due to their high levels of intraspecifc diversity which gives rise to a large range in data availability, considerations, and approaches for assessments and LRP development. In this paper, we identify six principles for developing LRPs for Pacifc salmon that are adapted from principles used more broadly among marine species. One principle unique to Pacifc salmon is that LRPs should be aligned with Canada's Wild Salmon Policy (WSP) objective of preserving biodiversity of salmon at the scale of Conservation Units (CUs), which are nested within SMUs. We developed methods for calculating LRPs, and established guidelines on how to implement them including under which conditions they should or should not be applied. We propose that LRPs be identifed from the proportion of CUs that have status above the Red zone for WSP status assessments, as a default approach. This provides some consistency with status assessments already produced under the WSP, and can inform management decisions for harvest, habitat and hatcheries that often occur at fner, CU scales. To supplement the default approach, we provide LRPs based on metrics of aggregate abundances for the entire SMU, which may be required for fsheries management purposes in some cases. These latter LRPs are derived to have a desired probability of all component CUs being above Red status given an assumed relationship between aggregate abundance and the probability that all CUs will be above Red status. We identify uncertainties associated with each approach, and describe how they can be applied across a range of data types, qualities and quantities. Analyses to support our development of guidelines has been informed by three cases studies: Interior Fraser Coho Salmon Oncorhynchus kisutch, West Coast Vancouver Island Chinook Salmon, O. tshawytscha, and Inside South Coast Chum Salmon, O. keta, excluding the Fraser River. [ABSTRACT FROM AUTHOR]