Many populations of Sockeye Salmon Oncorhynchus nerka in the eastern North Pacific Ocean experienced significant productivity declines that began about 1990, but there is no consensus on the mechanisms responsible. To better understand Sockeye Salmon survival trends, we examined the 50-year time series for two age-classes of Sockeye Salmon smolts from Chilko Lake in central British Columbia. Arranging survival time series for both age-classes by ocean entry year and combining them, weighted by a proxy model of sampling variance, reduced the sampling variance in the original age-1 smolt survivals sufficiently to indicate a linear trend of increasing survival from 1960 to 1990 that suddenly changed at or near 1991 to a lower and declining trend from 1992 to 2008. Neither density nor mean length influenced smolt survival. Returns in a given year were not good predictors of siblings returning in subsequent years. Time spent at sea increased linearly beginning around 1970. Although smolt survivals differed between ecosystem regimes, there was only the one clear pattern break about 1991. To improve our understanding of mechanisms, survival trends were compared with environmental indices that included catches and hatchery releases of potentially competing salmon from around the North Pacific Ocean. Smolt survivals were more similar to abundance indices of Sockeye Salmon, Chum Salmon O. keta, and Pink Salmon O. gorbuscha than to indices of global, regional, or local ocean climate. Our results are consistent with the hypothesis that salmon productivity in the North Pacific declined soon after 1990. We present a simple model to illustrate how increased competition at sea, related to the release of large numbers of hatchery salmon, in conjunction with changes in ocean productivity, may have played a significant role in improving Sockeye Salmon survivals while reducing their growth before 1991. After 1991, these factors may have acted to reduce survivals while the growth of survivors showed no effect.Anadromous Pacific salmon Oncorhynchus spp. comprise a multispecies complex of varying productivities. Their recent abundance in the Pacific Ocean, as reflected by commercial catch, is as high as it has ever been (Irvine and Fukuwaka 2011). Global abundances are driven primarily by Pink Salmon O. gorbuscha and Chum Salmon O. keta, as well as, particularly in the eastern North Pacific Ocean, by Sockeye Salmon O. nerka (Eggers 2009;Ruggerone et al. 2010;Irvine and Fukuwaka 2011). The status of Sockeye Salmon populations varies among regions however, and in British Columbia's Fraser River, low Subject editor: Suam Kim, Pukyong National University, Busan, South Korea *Corresponding author: james.irvine@dfo-mpo.gc.ca Received February 8, 2013; accepted July 24, 2013 numbers of returning salmon in recent years are a major concern (Grant et al. 2011;Rand et al. 2012).The Fraser River watershed is one of the world's greatest salmon producers (Northcote and Larkin 1989), although numbers returning annually are highly variable...

The present study examines sources of the interannual variability in salinity on

Time series of temperature, salinity and ice area from the Newfoundland and Labrador Shelves during 1951-86 are examined to determine the temporal and spatial scales of variability outside of the annual band. Significant interannual (periods of 1.8-18 a) variability of temperature (root-mean-square amplitude 0.5°C) and salinity ( 0.1) is found at all depths and, for depths greater than about 100 m, is exceeded or matched only by the annual component. Vertical scales of the low-frequency variability for the depth range 0-75 m are estimated to be twice as large for salinity (60 m) as for temperature (30 m); whereas, for the depth range of 75-175 m, they are the same (90 m) and exceed the scales for the 0-75 m interval. The dominance of low-frequency energy and the size of the vertical scales at depths 100 m suggest that the irregular-temporal and widely spaced vertical sampling of the hydrographic time series would not affect a study of interannual variability in this region. The analysis also suggests that the subsurface low-frequency variability is correlated over horizontal distances of about 1000 km, though the time series are too short to establish statistical confidence. RÉSUMÉ On examine des séries chronologiques de données de température, de salinité et d'englacement pour les plates-formes de Terre-Neuve et du Labrador, portant sur la période 1951-1986, dans le but de déterminer les échelles temporelles et spatiales de variabilité hors de la bande annuelle. Une importante variabilité interannuelle (périodes de 1,8 à 18 a) des températures (amplitude moyenne quadratique 0,5°C) et de la salinité ( 0,1) est Temperature and Salinity Variability on the Eastern Newfoundland Shelf / 121observée à toutes les profondeurs; pour les profondeurs de plus d'environ 100 m, elle n 'est dépassée ou égalée que par la composante annuelle. On estime que les échelles verticales de variabilité aux basses fréquences, pour la fourchette de profondeurs 0-75 m, sont deux fois plus grandes pour la salinité (60 m) que pour la température (30 m), tandis que pour la fourchette de pronfondeurs 75-175 m, elles sont égales (90 m) et dépassent les échelles déterminées pour les profondeurs 0-75 m. La prédominance d'une énergie de basse fréquence et la grandeur des échelles verticales à des profondeurs 100 m indiquent que l'échantillonnage temporel irrégulier à grands intevalles de la série chronologique de données hydrographiques n 'influerait pas sur une étude de la variabilité interannuelle dans cette région. L'analyse révèle également que la variabilité aux basses fréquences sous la surface est corrélée sur des distances horizonatales de 1000 km environ, même si les séries chronologiques sont trop courtes pour établir une confiance statistique.

A 36-year time series from an oceanographic station, Sta. 27, located off St John's, Newfoundland, has been used to derive the amplitudes and phases of the annual harmonics of temperature and salinity at fixed depths from 0 to 175 m. The analysis has been also carried out for the Newfoundland and Labrador Shelf, divided into about 40 areas, using monthly mean values from the available literature. At the surface, temperature (salinity) amplitudes are about 5°C (0.5-1.0) decreasing to <1°C (0.1) at 150 m. The surface temperature (salinity) amplitude is generally lower (higher) in the north. The phase of the annual harmonic increases almost linearly with depth at least for the upper 75 m in most regions and to the bottom at Sta. 27. Surface temperature amplitudes are nearly in phase (±6 d) throughout the region. On the other hand, the surface salinities in the north generally lead those in the south. Simple kinematic models that incorporate vertical diffusion and horizontal advection are developed in order to interpret the observations. The results indicate that vertical mixing in the region could be parametrized by a diffusion coefficient of about 10 -4 m 2 s -1 and that horizontal currents of about 0.2 m s -1 (0.1 m s -1 ) are representative of the upper 50 m (50-100 m). Other processes such as the annual ice cycle and runoff from the land are identified as important. RÉSUMÉ On a utilisé une série chonologique de 36 années à partir des données de la station océanique « STA 27 », au large de St John's (Terre-Neuve), pour dériver l'ampleur et la phase des harmoniques annuelles de température et salinité à des profondeurs fixes de 0 à 175 m. On a aussi étudié les plates-formes continentales du Labrador et de Terre-Neuve, divisées en près de 40 zones, à l'aide de données mensuelles moyennes disponibles. En surface, l'amplitude de la température (salinité) est de 5°C (0,5-1,0) diminuant à <1°C (0.1) à 150 m. L'amplitude de la température (salinité) en surface est généralement plus (1) 1991, 14-36 0705-5900/91/0000-0014S01.25/0 Annual Harmonics of T and 5 on the Eastern Newfoundland Shelf / 15 basse (élevée) au nord. La phase de l'harmonique annuelle augmente presque linéairement avec la profondeur dans au moins les 75 premiers mètres dans la plupart des zones et jusqu'au fond à la STA 27. Les amplitudes de la température en surface sont presque en phase (±6 d) dans toute la région. Cependant, au nord, la salinité en surface est est en avance de celle au sud. On a élaboré des modèles cinématiques simples qui incluent la diffusion verticale et l'advection horizontale afin d'étudier les observations. Il en résulte que l'on pourrait paramétriser le mélange vertical dans la région avec un coefficient de diffusion d'environ 10 -4 m 2 s -1 et que les courants horizontaux de près de 0,2 m s -1 (0,1 m s -1 ) représentent les 50 premiers mètres (50-100 m). On considère que le cycle annuel des glaces et le ruissellement sont aussi importants.