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.

Predicting climate effects on Pacific sardine

Abstract: For many marine species and habitats, climate change and overfishing present a double threat. To manage marine resources effectively, it is necessary to adapt management to changes in the physical environment. Simple relationships between environmental conditions and fish abundance have long been used in both fisheries and fishery management. In many cases, however, physical, biological, and human variables feed back on each other. For these systems, associations between variables can change as the system evolves in time. This can obscure relationships between population dynamics and environmental variability, undermining our ability to forecast changes in populations tied to physical processes. Here we present a methodology for identifying physical forcing variables based on nonlinear forecasting and show how the method provides a predictive understanding of the influence of physical forcing on Pacific sardine.

Potential impacts of climate change on Northeast Pacific marine foodwebs and fisheries

Abstract: Although there has been considerable research on the impacts of individual changes in water temperature, carbonate chemistry, and other variables on species, cumulative impacts of these effects have rarely been studied. Here, we simulate changes in (i) primary productivity, (ii) species range shifts, (iii) zooplankton community size structure, (iv) ocean acidification, and (v) ocean deoxygenation both individually and together using five Ecopath with Ecosim models of the northeast Pacific Ocean. We used a standardized method to represent climate effects that relied on time-series forcing functions: annual multipliers of species productivity. We focused on changes in fisheries landings, biomass, and ecosystem characteristics (diversity and trophic indices). Fisheries landings generally declined in response to cumulative effects and often to a greater degree than would have been predicted based on individual climate effects, indicating possible synergies. Total biomass of fished and unfished functional groups displayed a decline, though unfished groups were affected less negatively. Some functional groups (e.g. pelagic and demersal invertebrates) were predicted to respond favourably under cumulative effects in some regions. The challenge of predicting climate change impacts must be met if we are to adapt and manage rapidly changing marine ecosystems in the 21st century.

Twenty-Six Years of Green Turtle Nesting at Tortuguero, Costa Rica: An Encouraging Trend

Abstract: The green turtle (Chelonia mydas) population that nests at Tortuguero, Costa Rica, is the largest in the Atlantic by at least an order of magnitude. Surveys to monitor the nesting activity on the northern 18 km of the 36-km beach were initiated in 1971 and extended to the entire beach in 1986. From the survey data, we estimated the total number of nesting emergences on the northern 18 km for each year from 1971 through 1996. Evaluation of the trend in nesting emergences indicated a relatively consistent increase from 1971 to the mid-1980s, constant or perhaps decreasing nesting during the late 1980s, and then resumption of an upward trend in the 1990s. Evaluation of trends in sea turtle nesting populations requires many years of data because of the large degree of annual variation in nesting numbers. The trends reported in this study must be evaluated with caution for several reasons. First, if the mean number of nests deposited by each female each year (clutch frequency) varies significantly among years, changes in the number of nesting emergences among years could reflect changes in the number of nesting females, clutch frequency, or both. Second, we only assessed the trend in one segment of the population (mature females), which may or may not represent the trend of the entire green turtle population and which, because of late maturity, may not reflect changes in juvenile mortality for many years. Third, survey frequency, and thus confidence in annual estimates, varied among years. The upward population trend must be assessed from the perspective of the catastrophic decline that the Caribbean green turtle populations have experienced since the arrival of Europeans. If careful management is continued in Costa Rica and adopted throughout the region, the collapse of the Caribbean green turtle populations—which seemed imminent in the 1950s—can be avoided. La poblacion de tortuga verde (Chelonia mydas) que anida en Tortuguero, Costa Rica, es la mas grande del Atlantico en por lo menos un orden de magnitud. Muestreos para monitorear la actividad de nidada en 18 km al norte de un total de 36 km de la playa fueron iniciados en 1971 y extendidos para toda la playa en 1986. De los datos de muestreos estimamos que el numero total de salidas para anidar indican un incremento relativamente consistente de 1971 hasta mediados de los 1980s y la reaparicion de una tendencia de incremento en los 1990s. Evaluaciones de tendencias en poblaciones de tortugas anidando requieren de muchos anos de datos debido al alto grado de variacion anual en los numeros de nidaciones. Las tendencias reportadas en este estudio deben ser evaluadas con precaucion por diversas razones. Primero, si el promedio de nidos depositados por cada hembra cada ano ( frecuencia de nidada) varia significativamente entre anos, cambios en el numero de salidas para anidar entre anos pueden reflejar cambios en el numero de hembras anidando, en la frecuencia de nidada o ambos. Segundo, unicamente evaluamos las tendencias en un segmento de la poblacion y la cual, puede o no, representar las tendencias de toda la poblacion de tortuga verde, la cual a su vez, podria no reflejar cambios en la mortalidad de juveniles por muchos anos debido a una madurez tardia. Tercero, los muestreos de frecuencias y por lo tanto la confianza en las estimaciones anuales varian entre anos. La tendencia creciente de la poblacion debera ser evaluada desde la perspectiva de una disminucion catastrofica que las tortugas verdes del Caribe han experimentado desde el arribo de los Europeos. Si el manejo cuidadoso continua en Costa Rica y es adoptado en toda la region, el colapso de las poblaciones de tortuga verde del Caribe—que parecia inminente en los 1950s—puede ser evitado.

Is the collapse of shark populations in the Northwest Atlantic Ocean and Gulf of Mexico real

Abstract: Increasing fishing pressure on sharks stocks over recent decades has resulted in declines of many populations and led to increasing concerns for their conservation. The extent of these declines, however, has been highly variable—the result of the level of fishing, ocean conditions, and the life history of individual species. Two recent articles have described the collapse and possible extirpation of shark populations in the northwest Atlantic Ocean and Gulf of Mexico. Herein, we examine the results of these two papers commenting on the data sets used, comparing them to other available data sets, and critically evaluating the analyses and conclusions. We argue that these conclusions have been overstated because: (1) the analyses were based on a limited number of data sets, (2) the data sets themselves are inadequate to describe the status of all shark populations in the northwest Atlantic Ocean and Gulf of Mexico reported in these studies, (3) available data sets that could produce different concl...

The importance of edge for natant macrofauna in a created salt marsh

Abstract: The relationship between marsh edge and animal use was examined in a plantedSpartina alterniflora marsh located in the Galveston Bay system of Texas. A completely randomized block experimental design was used with each of four blocks containing a control and experimental sector. Marsh edge was increased through the construction of channels in experimental sectors. Channel construction had no detectable effect on marsh surface elevation. Effects of these simulated tidal creeks on habitat use were examined by sampling nekton at high tide with drop enclosures both on the marsh surface and within the channels. Crustaceans dominated the nekton, and use of the marsh surface in experimental sectors was significantly higher than in controls; densities of brown shrimpPenaeus aztecus, white shrimpP. setiferus, and daggerblade grass shrimpPalaemonetes pugio were 4.6 to 13 times higher near the channels. Polychaete densities in marsh sediments were also significantly higher near channels, and densities of decapod predators were positively correlated with densities of these infaunal prey. Thus, channel effects on natant decapods may have been related to the distribution of prey organisms. However, increased densities of natant fauna along the channel edge may simply reflect a requirement for departure from the marsh surface at low tide. Marshsurface densities of small bait fishes, bay anchovyAnchoa mitchilli and the inland silversideMenidia beryllina, also increased near channels, but highest densities of these fishes were in the creeks themselves. The abundance and distribution of juvenile blue crabsCallinectes sapidus and gulf marsh fiddler crabsUca longisignalis were not affected by the addition of experimental channels. Overall, the study results indicate that habitat value of created salt marshes can be enhanced by incorporating tidal creeks into the marsh design.