National Marine Fisheries Service

About: National Marine Fisheries Service is a government organization based out in Silver Spring, Maryland, United States. It is known for research contribution in the topics: Population & Fisheries management. The organization has 3949 authors who have published 7053 publications receiving 305073 citations. The organization is also known as: NOAA Fisheries & NOAA National Marine Fisheries Service.

Post-Hydropower System Delayed Mortality of Transported Snake River Stream-Type Chinook Salmon: Unraveling the Mystery

Abstract: Past research indicates that on an annual basis, smolts of stream-type Chinook salmon Oncorhynchus tshawytscha collected at Snake River dams and transported by barge to below Bonneville Dam have greater post-hydropower system mortality than smolts that migrate in-river. To date, this difference has most commonly been attributed to stress from collection and transportation, leading to decreased disease resistance or predator avoidance ability. Using both hatchery and wild passive integrated transponder (PIT) tagged Chinook salmon, we explored two mechanisms that either separately or jointly contributed to an alternative explanation: Altered timing of ocean entry and lost growth opportunity leading to size-selective predation. Based on weekly estimates of in-river survival and adult return rates of smolts that were transported or that migrated in-river between Lower Granite and Bonneville dams, we found greater post-hydropower system mortality for smolts transported early in the season but greater ...

Interacting effects of density and temperature on body size in multiple populations of Chinook salmon.

Abstract: 1. The size individuals attain reflects complex interactions between food availability and quality, environmental conditions and ecological interactions. A statistical interaction between temperature and the density of conspecifics is expected to arise from various ecological dynamics, including bioenergetic constraints, if population density affects mean consumption rate or activity level. Density effects on behaviour or size-selective predation could also generate this pattern. This interaction plays an important role in bioenergetic models, in particular, and yet has not been documented in natural populations. 2. The lengths of 131 286 juvenile wild Chinook salmon (Oncorhynchus tshawytscha) across 13 populations spread throughout the Salmon River Basin, Idaho, USA over 15 years were compared to test whether juvenile density alters the relationship between body size and temperature. 3. Strong evidence for a negative interaction between mean summer temperature and density emerged, despite the relatively cool temperatures in this high elevation habitat. Growth correlated positively with temperature at lower densities, but the correlation was negative at the highest densities. 4. This is the first study to document this interaction at such a large spatial and temporal scale, and suggests that warmer temperatures might intensify some density-dependent processes. How climate change will affect individual growth rates in these populations will depend intimately on ecological conditions, particularly food availability and population dynamics. More broadly, the conditions that led to the interactions observed in our study - limited food availability and temperatures that ranged above those optimal for growth - likely exist for many other natural populations, and warrant broader exploration.

Pollutants and fish predator/prey behavior: A review of laboratory and field approaches

Abstract: Fish behavior can be altered by contaminants. There is an extensive literature on laboratory behavioral assays, with many chemicals impairing feeding or predator avoidance. However, there is not extensive work on fishes that live in contami- nated environments. Therefore, we then review our recent research on feeding and trophic relations of populations from contami- nated estuaries compared with relatively unpolluted sites. The mummichog Fundulus heteroclitus, is a non-migratory fish; those from more contaminated areas are poor predators and slower to capture active prey (grass shrimp, Palaemonetes pugio). In the field, they consume much detritus and sediment, which is not nutritious. They are less active than fish from cleaner sites and more vulnerable to predation. They have altered thyroid glands and neurotransmitter levels, which may underlie altered behaviors. Fish from the reference site kept in tanks with sediment and food from the polluted site showed bioaccumulation and reduced prey capture after two months, although fish from the polluted site did not show significant improvement when maintained in a clean environment. Poor nutrition and predator avoidance may be responsible for their being smaller and having a shorter life span than reference fish. Bluefish Pomatomus saltatrix, are a marine species in which the young-of-the-year spend their first summer in es- tuaries. We found bioaccumulation of contaminants and reduced activity, schooling, and feeding in young-of-the-year bluefish from a relatively unpolluted site that were fed prey fish from a contaminated site. They also had altered thyroid glands and neuro- transmitter levels. Many field-caught specimens had empty stomachs, which is rare in this species. In the fall, when they migrate back out to the ocean, they are smaller, slower, and more likely to starve or to be eaten than those that spent their summer in cleaner estuaries (Current Zoology 58 (1): 9−20, 2012).

Identifying the contribution of wild and hatchery Chinook salmon (Oncorhynchus tshawytscha) to the ocean fishery using otolith microstructure as natural tags

Abstract: Quantifying the contribution of wild (naturally spawned) and hatchery Chinook salmon (Oncorhynchus tshawytscha) to the mixed-stock ocean fishery is critical to understanding their relative importance to the persistence of salmon stocks. The inability to distinguish hatchery and wild salmon has inhibited the detection of declines or recover- ies for many wild populations. By using Chinook salmon of known hatchery and wild origin, we established a baseline for separating these two sources using otolith microstructure. Otoliths of wild salmon contained a distinct exogenous feeding check likely reflecting an abrupt transition in food resources from maternal yolk not experienced by fish reared in hatcheries. Daily growth increments in otoliths from hatchery salmon immediately after the onset of exogenous feed- ing were wider and more uniform in width than those in wild fish. The discriminant function that we used to distin- guish individuals reared in hatcheries or in the wild was robust between years (1999 and 2002), life history stages (juveniles and adults), and geographic regions (California, British Columbia, and Alaska) and classified fish with ~91% accuracy. Results from our mixed-stock model estimated that the contribution of wild fish was 10% ± 6%, indicating hatchery supplementation may be playing a larger role in supporting the central California coastal fishery than previ- ously assumed. Resume : La mesure des contributions des saumons chinook (Oncorhynchus tshawytscha) reproduits en nature (sauva- ges) et en pisciculture a la peche commerciale marine de stock mixte est essentielle pour comprendre leur importance relative dans la persistance des stocks de saumons. L'impossibilite de distinguer entre les saumons de pisciculture et les saumons sauvages a empeche la detection des declins et des recuperations chez de nombreuses populations sauvages. En utilisant des saumons chinook d'origine connue en nature ou en pisciculture, nous avons etabli des criteres de base pour separer les deux sources d'apres la microstructure des otolithes. Les otolithes des saumons sauvages portent une marque distincte exogene d'alimentation qui reflete sans doute une transition abrupte dans les ressources alimentaires apres l'epuisement du jaune d'oeuf maternel, ce qui ne survient pas chez les poissons eleves en pisciculture. Les zones de croissance journaliere dans les otolithes des saumons de pisciculture immediatement apres le debut de l'alimentation exogene sont plus larges et d'epaisseur plus uniforme que celles des poissons sauvages. La fonction discriminante que nous utilisons pour distinguer les individus eleves en pisciculture et en nature est robuste en fonction des annees (1999 et 2002), des stades du cycle biologique (jeunes et adultes) et des regions geographiques (Californie, Colombie-