Hydrographic Conditions on Flemish Cap in July 2001

Hydrographic conditions on Flemish Cap in July 2001 are described after a survey with 94 CTD stations. Current conditions over Flemish Cap are described and compared with those observed in previous years. The superficial water around the Cap at shallow depth is Labrador Water that advents favoured by the anticyclonic circulation over the cape. Since the middle-1990s temperatures have been increasing until 1999. In 2001 the superficial waters (<100 m) are warmer (+1ºC) and saltier (+0.5) that the mean of 25 past years. In depth, a well-developed layer with temperatures around 3.5ºC and salinity 34.85 was observed all around the Cap over 200 m depth

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

A possible relation between sardine fisheries and oceanographic conditions in NW Spanish coastal waters

The NW of more often the shelf sardine in Spain is influenced by episodic upwelling which occurs between March and October. The consequent enrichment of waters is the origin of a very important fishery for the area. Eggs and larval survival is directly related to the oceanograph¡c conditions between the date of birth and recruitment. Laryal survival seems to be related essentially to weak upwelling conditions since they favour the non-dispersion of eggs (larvae) and allow growth of medium sized phytoplankters as suitable food. On the other hand, strpng upwelling causes dispersion of eggs (larvae) and favours growth of very large phytoplankton specles, mainly diatoms, that are thought to be un-suitable food for larvae. However, strong upwelling conditions are favorable for sardine adults, since the large phytoplankters growing during these upwelling events were found to be the main food supply, as shown by the study of stomach contents

The effect of environmental changes in the Galician sardine fishery

Annex 6The highest catches of the Iberian sardine stock are taken from the southern part of Galician waters (NW corner of the Iberian Peninsula) and northern Portugal. Landings are mainly composed of younger fish, which reflects the proximity of the main recruitment area to the fishery grounds. Since 1978 there has been an improvement in the knowledge of the biology and stock dynamics of sardine around the Atlantic Iberian waters. In the last decade a consecutive years with poor recruitments result in a depletion of stock below limits previously recorded. The recruitment processes seem to be driven by oceanographic (local) and climatic (global) events, this dependence on both phenomena may explain the fluctuations on the landings in the sardine fisheries in Atlantic Iberian waters. Given the dependence of the fishery in this area on the strength of the recruitment, different relationship between biotic components (spawning stock size, recruitment, landings and recruitment landings) and abiotic: climatic indices (NAO-winter, Gulf Stream and AMO) and local oceanographic coastal events (upwelling and poleward current) were analysed. In the analysis of the abiotic series in the period (1978–2005), there appears to be a shift in the general trend in 1995. In addition at the end of the nineties several consecutive years with poor recruitment result in a depletion of the stock below limits previously recorded as well as changes in the distribution area. Before the shift was observed the recruitment variability could be explain by the environmental variables, but since then the correlation is poor

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

´Primary productivity in winter in the Ria of Pontevedra (NW of Spain) and the changes caused by the contamination

Spatial distribution in winter of the primary productivity in the Ria of Pontevedra (NW of Spain), is shown. It is proved that industrial and urban efluents have a negative effect on photosynthesis, especially on the surface of the water, and on the Northern Coast, which is in accordance with the dynamics of the RiaOn indique la distribution spatial d'hiver de la production primaire dans la Ria de Pontevedra (NO d'Espagne). Les debuts industrielles et urbains affectent negativement la photosynthése. Cette influence est plus noté dans la surface et spécialement dans la zone Nord de la Ria

Abundance estimation and distribution of sardine in Northern Spain (north of IXa and VIIIc divisions)

Since 1986, an acoustic survey programme have been carried out for assessment of sardine: stock in Atlantic waters of the Iberian Peninsula. Sardine abundance estimated by length and age groups and oceanographic conditions in Galician and Cantabrian waters from 1986 to 1993 were studied. The biomass decreased after 1986 despite the occurrence of two very good year classes 1983 (the strongest ever recorded since 1976) and in 1987. The 1991 recruiting year c1ass seems to be a good one in the 1993 survey.Depuis 1986, un programme de sondage acoustique a été fait pour l'evaluation du stock de sardines dans les eaux atlantiques de la Peninsule Iberique. L'abondance de sardines, estimée par des groupes de taille et d'age, et les conditions oceanographiques dans les eaux de la Galicie et de la mer Cantabrique a été étududiée depuis 1986 jusqu'à 1993. La biomasse a diminué après 1986, malgre la presence de deux bonnes années 1983 (la plus forte jamais registrée depuis 1976) et 1987

Winter distributions of Dinophysis populations: do they help to predict the onset of the bloom?

Blooms of diarrhetic shellfish toxin (DST) producers of the genus Dinophysis (D. acuminata, D. acuta) pose the main threat to the sustainable exploitation of cultivated mussels and other bivalves on the Atlantic coasts of Europe. Dinophysis species do not rely on cysts as a seeding strategy. Detection and evaluation of holoplanktonic populations surviving after bloom decline may be the key to predict the initiation of next year’s bloom. Three cruises were carried out on the NW Iberian shelf in February 2013 (DINVER 2013), January 2006 (DINVER 2006) and May-June 1993 (MORENA 93) to explore winter (D. acuminata) and pre-bloom (D. acuta) distributions of harmful microalgal species. Sampling protocols were adapted to be able to detect extremely low densities (1-5 cells l-1) of Dinophysis species. Potential inoculum populations in retention areas, as previously described for other species in upwelling regions, were not found on these cruises. Here we explore retrospectively data from these cruises, identify hydrodynamic patterns, and accompanying microplanktonic communities, in an attempt to untangle a crucial question in Dinophysis population dynamics: how to predict the initiation of the Dinophysis growth season.ISSHAEn prens

Improving the knowledge of sub-surface temperature, salinity and fluorescence variability patterns on the Southern Coast of Galicia

Since 2008, the Instituto Español de Oceanografía (IEO) keeps installed a thermosalinometer (TSG) on board of R/V J.M. Navaz that operates on Galician coastal waters. Weekly, it covers the area between Vigo and Muros in the framework of an harmful algal bloom monitoring. High resolution and quality coastal data are very important in order to develop accurate behavior models. The TSG continuously measures the sea subsurface salinity, temperature, and fluorescence along the ships tracks. The classical approach to distribution maps is performing objective analysis of the collected data and assumes errors associated to coastal features. Data-Interpolating Variational Analysis (DIVA) allows the spatial interpolation of data over an adaptable mesh grid, taking into account coastlines and inlets, but also advection constraints. Calculations are optimized and rely on a finite element resolution and the software allows optimizing the analysis parameters, checking for duplicates and performing quality controls. The results of performing and compare DIVA and objective analysis show slight differences that can be appreciated between the inner part of the inlets and the open sea areas. The relative length of the whole data set allows considering also monthly, seasonal and annual variability. These climatological results, that will be updated systematically, can be useful not only for scientific research but also for coastal management activities. All this products, together with quality check flags and metadata information, give added value to the original TSG measures and that will allow a future reuse of data