Links between North Atlantic sardine recruitment and its environment

The year class strength of the Iberian sardine is regulated by hydroclimatic conditions in the North Atlantic. The low recruitment values of recent years have been caused by reduction of the reproductive stock. The reproductive strategy of the sardine,with autumn and spring spawning seasons, produces two recruitment periods each year. This reproductive strategy is adapted to the oceanographic regime in the area, with coastal upwelling between April and September, and a northerly surface coastal current in winter. Variations in the intensity and timing of the winter current affect the success of the autumn spawning and can lead to recruitment failure at the end of spring. Variations in the intensity and timing of the northerly wind component, which generates upwelling, control the success of spring spawning. On the basis of oceanographic data and yearly recruitment from 1975 to 1997, we try to analyze the recruitment variability induced by the marine climate to the Iberian sardine stock

Meso- and Bathypelagic Fish Interactions with Seamounts and Mid-Ocean Ridges

The World Ocean\u27s midwaters contain the vast majority of Earth\u27s vertebrates in the form of mesoand bathypelagic (\u27deep-pelagic,\u27 in the combined sense) fishes. Understanding the ecology and variability of deep-pelagic ecosystems has increased substantially in the past few decades due to advances in sampling/observation technology. Researchers have discovered that the deep sea hosts a complex assemblage of organisms adapted to a “harsh” environment by terrestrial standards (i.e., dark, cold, high pressure). We have learned that despite the lack of physical barriers, the deep-sea realm is not a homogeneous ecosystem, but is spatially and temporally variable on multiple scales. While there is a well-documented reduction of biomass as a function of depth (and thus distance from the sun, ergo primary production) in the open ocean, recent surveys have shown that pelagic fish abundance and biomass can \u27peak\u27 deep in the water column in association with abrupt topographic features such as seamounts and mid-ocean ridges. We review the current knowledge on deep-pelagic fish interactions with these features, as well as effects of these interactions on ecosystem functioning. We highlight the recent discoveries from the Mid-Atlantic Ridge (via the Census of Marine Life field project MAR-ECO) that were presented at the international symposium “Into the Unknown, Researching Mysterious Deep-Sea Animals,” hosted by the Okinawa Churaumi Aquarium, Okinawa, Japan, Feb 2007

Acoustic abundance estimation of pilchard (Sardina pilchardus Walb.) in Galician and Cantabric waters. August 1983

Results of the acoustic survey "Saracus-83" are reported in this paper. This cruise was carried out on board the research vessel "Cornide de Saavedra", in august 1983 off the Cantabric and Galician coasts in the north of Spain. The main objective of the survey was to estimate the abundance by age groups of pilchard (Sardina pilchardus Walb.) present in the area, being this population apart of the stock wich is considered to exist in the ICES divisions VIIlc and IXa. The total estimated biomass for pilchard was 697000 tons. The area of higher abundance was northern Galicia, between Ribadeo and Finisterre, that coincides with the upwelling area described.On presente ici les resultats de la campagne acoustique realisée par le B/R "Cornide de Saavedra" dans Aout 1983 au large des côtes Cantabrique et Galicienne du N et NW espagnol. Le but de cette campagne a été l'estimation de l'abondance par classe d'age de la sardine (Sardina pilchardus Walb.) dans l'aire prospectée qui appartient aux divisions VIIIc et IXa du ICES. La plus grande abondance a été la partie nord de la Galicie, entre Ribadeo et Finisterre, qui coincide avec la zone de "upwel1ing" deja signalée

Deep-Pelagic Fishes and the Mid-Atlantic Ridge: Interactions and Vectoring of Gelatinous Carbon to Higher Trophic Levels?

The assemblage structure and vertical distribution of deep-pelagic fishes relative to a mid-ocean ridge system is described from an acoustic and discrete-depth trawling survey conducted as part of the international Census of Marine Life field project MAR-ECO. A survey along the Mid-Atlantic Ridge (MAR), covering the full depth range (0 to \u3e3000 m) with a combination of gear types, was conducted to understand the role of the pelagic fauna in ecosystem dynamics. A total of 205 fish species were collected by midwater sampling. Depth was by far the primary assemblage composition determinant, with ridge section secondary. The dominant ichthyofaunal component was a widespread assemblage of fishes between 750-3000 m, from Iceland to the Azores. Some zonation was apparent in the northern and southern ends of this large depth stratum, with six smaller assemblages of fishes exhibiting limited distributions. Biomass per volume reached a water column maximum in the bathypelagic zone between 1500-2300 m. This stands in stark contrast to the general “open ocean” paradigm that biomass decreases exponentially from the surface downwards. As much of the summit of the MAR extends into this depth layer, a likely explanation for this midwater maximum is ridge association. Fish density within the benthic boundary layer (within 200 m of the ridge) was nearly double that of the water column and biomass was approximately 50% higher. Of the ‘ridge-associating’ species, two species known to consume gelata, Bathylagus euryops and Scopelogadus beanii, contributed over half of the fish biomass of this layer. These data suggest that a pelagic fish-gelata trophic linkage may be a key element of benthic-pelagic coupling over mid-ocean ridges, thus supporting enhanced nekton biomass over ridges in the absence of terrigenous nutrient input. Ongoing research to better understand this trophic linkage will be presented

The stock of Atlanto-Iberian sardine: possible causes of variability

Fluctuations in the Iberian stock in the period 1980-1989 have been examined, taking into account what is known of the biology of the species, oceanic and atmospheric parameters, and the fishing effort directed at this stock. During this period, there have been significant changes in recruitment, which was good in 1983 and 1987 and poor in 1982, 1985, 1986, and 1988. Some links between recruitment anomalies and environmental parameters (surface temperatures, prevailing winds, sea level) have been identified. Variations in recruitment can be explained on the basis of fluctuations in “environmental windows" during the periods of spawning and larval drift. The success of spawning is controlled by the existence of a favourable environment during larval drift into areas with weak upwelling and abundant food.Versión del edito

Space Shuttle ice suppression system validation, volume 3

The influence of nozzle size without wind, on wind penetration, the influence of nozzle pressure on wind penetration, wind velocity effects, nozzle pressure effects, nominal velocity, wind velocity effects on wind penetration, and nozzle azimuth angle effects are plotted

Space Shuttle ice suppression system validation, volume 1

Preliminary analytical considerations and the experimental investigation of the flow field for the desired configurations in the absence of wind effects are discussed. A wind tunnel test program to determine the effect of different wind conditions on ice suppression system (ISS) performance is also discussed

Some observations on the biology of sardine (Sardina pilchardus Walb.) off Galicia NW Spain

6392 specimen of sardines were sampled during the period 1980-1984. The spawning season was ca1culated from the monthly percentages of mature individuals, gonadosomatic index, condition factor and viscera1 fat. The size and age at first maturation and the size/weight ratio were calculated.Pendant la periode 1980-1984 des echantillonages biologiques regulieres sur la sardine ont ete realises et 6932 exemplaires ont été examinées. On determine la saison de ponte a partir de l'evolution mensuelle du pourcentage des individus mûrs et de la variation du l'indice gonadosomatique, le facteur de condition et la graisse viscerale. On calcule aussi la taille et l'age de premiere maturation et les equations taille/poid vive et poid eviscere