Koenings, ). P., H. ). Geiger, and 1. 1. Hasbrouck. 1993. Smolt-to-adult survival patterns of sockeye salmon (Oncorhynshus nerka): effects of smolt length and geographic latitude when entering the sea. Can. 1. Fish. Aquat. Sci. 50: 600-61 1. Variations in smolt-to-adult survival (SAS) of sockeye salmon (Oncorhynchus nerka) relative to smolt length and age and latitude of the nursery Bake outlet were explored for six stocks in Canada, Russia, and Alaska (W. E. Ricker. 1962. ). Fish. Res. Board Can. 19: 537-5601 and 12 Alaskan populations. SAS values ranged from <1 to 68% for age 1 ., 2., and 3. smolt populations of 54-200 mm in mean length. The common pattern underlying the SAS to smolt sine relationship, determined by nonparametric regression (loess), was nonlinear with f~snction-ally distinct zones. SAS of smaller smolts increased (0.3-0.5 (%) SAScmrn -') with size, but SAS of smolts >90-100 mm (6-8 g) did not. Variation in SAS was explained by srnolt sine (30%) and a south to north cline of nursery lakes (21 %j indexed by latitude. SAS of about 3 and 13% for threshold-sized age 1. smolts (60-65 mm) from southern and northern nursery lakes were consistent with sockeye biostandards for Canada (4.7%) and Alaska (1 2%1, respectively. The combined effects of latitude and smolt length on SAS resulted in larger smolts at higher (>60QN) latitudes having seven times the SAS sf smaller smolts at lower (<5%'N! latitudes. Chez six stocks trouvks au Canada, en Russie et en Alaska et qui ont dkja eke analyses par W. E. Ricker (1962. j. can. sci. halieut. aquat. 19 : 531-5630), ainsi que chez 12 populations d'Alaska, on a examine les variations de la survie du saumsneau a l'adulte ISSA) chez le saumon rouge (Oncorhynchus nerka) en fonctisn de la longueur et de I'2ge des saumoneaux, ainsi que de I'emplacenient de I'exutoire du lac d'alevinage. La SSA variait entre moires de 1 et 68 % dans les pop~slations de saumoneaux mesurant 54-200 mm de longueur moyenne et Ag6s de 1 ., 2. et 3. ares. Telle que deterrninke par une regression now parametrique (loess), I'allure commune de la relation entre la SSA et la taille des saumoneaux etait non lineaire et com~portait des zones fonctionnellement distinctes. La SSA des plus petits saumoneaux s'accroissait proportionnellement 2 la taille (0,3-0,5 (%) SSAamm-I), mais ce n16tait pas le cas de la SSA des saumoneaux de plus de 90-1 00 m m (6-8 g). bes variations de la SSA s'expliquaient par la ta~lle des saumoneaux (30 %) et I'existence d'un clivage, orient6 du sud au nord, des lacs d'alevindge (21 %) exprime en fonction de la latitude. La SSA d'environ 3 et 13 % chef les saumoneaux de taille minimale et 2gks de 1. an (60-65 mm) qui provenaient des lacs d'alevinage du sud et du nord etait conforme aux standards biollogiques du saumon rouge au Canada (4,7 %) et en Alaska (1 2 %), respsctivement. L'effet combink de la latitude et de la longueur des saumoneaux sur la SSA explique que les plus gsos saumoneaux des hautes latitudes (>60 "N) ont une SSA sept fois supkrieure A celle des petits sauni...

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ABSTRACT. The enzyme-linked immunosorbent assay (ELISA) and the fluorescent antibody test (FAT) were compared for their sensitivity in detection of Renibacterjum salmoninarum (Rs) in kidney tissues of Alaskan salmonids. The ELISA appeared to be more sensitive in detecting Rs infections. The FAT did not detect Rs in 80 % of the ELISA-positive samples but was positive for Rs in 28 'K, of the samples that were ELISA-negative. This contradiction may have been due to low-level washover of Rs cells from smears containing large numbers of Rs cells when slldes containing nlultiple samples were rinsed in d common vessel during the FAT procedures. The FAT routinely did not detect infections in Rs-positive fish the tissues of which produced a mean ELISA optical density value 50.173, and inconsistently detected infections in fish with ELISA values > 0.173 but < 0.978. The 0.978 optical density was the mean ELISA value at which the FAT routinely detected Rs-positive fish. Based on the ELlSA results, Rs occurred in only 9 % of the Alaskan Pacific salmon tested in both wild (85 "/U) and hatchery (81 %) stocks. The very high stock prevalences and levels of Rs antigen detected in wild trout Oncorhynch~~s spp., char Salvelinus spp., and grayling Thymallus arcticus having no clinical signs of bacterial kidney disease suggest these species may be somewhat resistant hosts and important freshwater reservoirs of Rs.

Kldney tissues from 5231 chinook salmon Oncorhynchus tshawytscha and 3793 coho salmon 0. kisutch adults used for spawnlng were examined for soluble antigen of Renibacterium salmo-11inarum (Rs) by the enzyme-linked lmmunosorbent assay (ELISA). The purpose of this study was to develop an extens~ve data base for establishing a negative-positive threshold optical density value for Rs-negative and-positive fish uslng commercially available ELISA reagents. Statistical evaluation of the estimated distribution of Rs-negative optical density values from coho a n d chinook salmon indicated the preliminary estimated negative-positive threshold value of 0.1 was not conservative enough. i.e. there was an unacceptably high probability that a large number of low-level Rs-positive fish were not identified. Consequently, a more conservative threshold value of 0.095 was chosen that erred in ~dentifying an acceptably low number of negative fish a s positive. At this threshold optical density value the ELISA could detect about 20 ng of Rs antigen ml-l of kidney homogenate.

Gulf menhaden (Brevoortia patronus) exhibited unprecedented juvenile recruitment in 2010 during the year of the Deepwater Horizon well blowout, exceeding the prior 39-year mean by more than four standard deviations near the Mississippi River. Abundance of that cohort remained exceptionally high for two subsequent years as recruits moved into older age classes. Such changes in this dominant forage fish population can be most parsimoniously explained as consequences of release from predation. Contact with crude oil induced high mortality of piscivorous seabirds, bottlenose dolphin (Tursiops truncatus), waders, and other fish-eating marsh birds, all of which are substantial consumers of Gulf menhaden. Diversions of fresh water from the Mississippi River to protect coastal marshes from oiling depressed salinities, impairing access to juvenile Gulf menhaden by aquatic predators that avoid low-salinity estuarine waters. These releases from predation led to an increase of Gulf menhaden biomass in 2011 to 2.4 million t, or more than twice the average biomass of 1.1 million t for the decade prior to 2010. Biomass increases of this magnitude in a major forage fish species suggest additional trophically linked effects at the population-, trophic-level and ecosystem scales, reflecting an heretofore little appreciated indirect effect that may be associated with major oil spills in highly productive marine waters.

This book that contains 38 research articles on marine ecology of Pacific salmon and steelhead trout, is dedicated to the International Year of the Salmon and is the first scientific publication that contributes to the library of the project.

To study family-specific variation in the survival of pink salmon Oncorhynchus gorbuscha, we partitioned family size into four life history divisions: (1) maternal fecundity, (2) deposition of fertilized eggs and egg loss from the redd, (3) freshwater survival (and male potency), and (4) marine survival. We directly measured the variability in fecundity and then measured the family-specific variability of freshwater survival in several Alaskan hatchery populations. Next, we measured freshwater survival in spatially clustered groups of wild pink salmon (not identified to a specific dam or sire) in Prince William Sound, Alaska. Drawing on estimates of the family-specific variation of marine survival in pink salmon from previous studies, we concluded that family-specific egg deposition processes and family-specific variability in the marine environment were the primary sources of the overall variability in pink salmon family size, at least in the populations studied. We hypothesize that the freshwater environment generally induces lower variability in family size than does the marine environment. If this is so, it appears that pink salmon populations are more finely adapted to the freshwater environment, presumably because this environment is more constant. Finally, we speculate that the marine environment is too unpredictable to permit the same level of adaptation of many traits closely linked to marine survival.

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