The Physiological Basis of Decompression. Undersea and Hyperbaric Medical Society. Consultado el 12 de marzo de Archivado desde el original el 21 de mayo de Relations of isobaric gas counterdiffusion and decompression gas lesion diseases. In Vann, RD. Retrieved 10 January Report to the Office of Naval Research. Annual Scientific Meeting held May 26—30, Archivado desde el original el 15 de marzo de Journal of Applied Physiology 94 6 : Consultado el 10 de enero de Neuman Bennett and Elliott's physiology and medicine of diving, 5th Rev ed.
United States: Saunders Ltd. Consultado el 21 de octubre de Silla, E. Hampel The Encyclopedia of the Chemical Elements. New York: Van Nostrand Reinhold. ISBN Consultado el 7 de mayo de Consultado el 13 de mayo de Consultado el 5 de abril de Proceedings of the 3rd annual Canadian Ocean Technology Congress. Toronto, Canada. Journal of the Undersea and Hyperbaric Medical Society.
Undersea and Hyperbaric Medicine, Inc. Lysaker, Norway: Standards Norway. Consultado el 27 de noviembre de Annual Scientific Meeting. Michigan Sea Grant College Program. Decompression—Decompression Sickness. Berlin New York: Springer-Verlag. Lang, and A. Trondheim: Norwegian University of Science and Technology.
Bubble Decompression Strategies. Immersed 3 3 : A thermodynamic approach arising from a study on Torres Strait diving techniques. Hvalradets Skrifter, Nr.
Journal of Hygiene 8 3 : Consultado el 30 de mayo de Bachrach A. Bethesda: Undersea Medical Society. Undersea Biomedical Research 2 4 : Sub-Aqua Association. Alert Diver. Diver Alert Network. Consultado el 3 de agosto de Archivado desde el original el 6 de septiembre de Consultado el 26 de septiembre de Bishop Museum. Consultado el 9 de septiembre de DAN Europe website.
DAN Europe. Sensitive zones In principle, all of the coastal area should be subject to strict monitoring to ensure it is in a good ecological state. Nevertheless, whilst the need to exploit all of their resources sustainably is understood, it is necessary to define the areas which due to their oceanographic and ecological characteristics are most sensitive to human pressure. In this sense, areas must be protected that are especially relevant because of the presence of marine species that are in regression or endangered. The same goes for zones of high productivity, zones for spawning, reproduction and breeding, zones that constitute migratory paths for birds and marine mammals, and fragile ecosystems corals, spermatophyte meadows, wetlands, etc.
It is necessary to gain more knowledge about these zones and to draw up schemes to manage them, so that their great ecological importance is guaranteed and we can thus ensure the sustainability of the marine ecosystems. Looking into the future Finally, it may be said that we are in time.
The future of our coasts and seas calls for collective awareness of the great ecological importance of these zones, and an understanding that some processes that are already occurring, such as climate change, which threaten life on the planet as we know it, depend on the health of these ecosystems. For this to come about, it is necessary for governments to allot more resources to environmental education.
This should start from a very early age, and particular activities that affect the common good should be chased up and corrected. In addition, it is important to keep improving knowledge of the processes that govern ecosystems.
Management policies for the environment and marine resources must be based on the best knowledge available. To do so, it is crucial to continue investing in training and research.
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If we do not wish to lose resources, ecosystems and biodiversity, it is necessary to build knowledge that enables us to understand and manage the complexity of nature. Spain is the seventh largest worldwide exporter of wild fish, with 0. In addition, it regularly exploits four of the ten species in most demand in the world Table 1. The ten most exploited species in the world in This gives an idea of the importance of our fleet, and Spain's responsibility in the face of fishing overexploitation.
The technical characteristics of the rest of the fleet are very diverse; in Cantabria and in the Basque Country steel vessels of great length predominate, 28 m on average dedicated to seine fishing, with reels of one and three wheels, in Andalusia and in Valencia polyester and wooden boats of medium length predominate, Therefore, the fleet is not very uniform, and is multi-specific and multi-professional. The Iberian peninsula is located in a geographically strategic situation, since at least three bio-geographical regions meet on its coasts: Lusitania, of temperate-cold character extending from the English Channel to the straits of Gibraltar , Mauritania, of warm character extending between Cape Verde and the straits of Gibraltar , and Mediterranean, of temperate character extending throughout the entire Mediterranean Sea basin.
This has favoured bio-geographical particularities as it is a transit zone between the Mediterranean Sea, the temperate-warm Atlantic and the cold Atlantic. Due to this unique situation on the Spanish coasts, a wide biodiversity exists that has encouraged particularly extensive fishing activity.
In fact, there are scientists such as Dr. Boris Worn and his colleagues who predict a total collapse in the world's fishing stocks around Even though other authors think that this prediction is exaggerated, it is evident that an international crisis in fishing productivity and its impact on ecosystems does exist; moreover, if extraction continues at current levels the stocks will continue to be irreversibly depleted until there is a total collapse.
There are many examples of species of economic importance that suffer overexploitation and this has repercussions on the local economy of many Spanish towns, like the hake Merluccius merluccius , the swordfish Xiphias gladius or the black-spot sea bream Pagellus bogaraveo , to mention a few. However, there are two species that support important industries, one in the north and the other in the south: the anchovy Engraulis encrasicolus and the red tuna Thunnus thynnus , which deserve special attention. The anchovy is a typical small pelagic species with a short life cycle maximum years , intense growth, early maturity and seasonal migratory reproduction.
LO MÁS VISTO
During these reproductive migrations, it concentrates in the Bay of Biscay in great shoals near the coast, when the opportunity to catch it is taken through the art of seine fishing. Up to the 19th century, fishing in the north of Spain had not varied much since the Middle Ages. It focused on the so-called deep sea species sea bream and tunas Thunnus sp. Nevertheless, a pickling and salting industry had grown which was used mainly for sardines, but with little success.
This was the panorama at the end of the decade of , when the enormous shoals of anchovy were hardly exploited, while its natural predators and competitors, tuna and sardine respectively, were being actively caught. In the Mediterranean, however, the anchovy had been exploited since the time of the Phoenicians 5th century BC , but it was during the economic growth of the reunified Italy when a modern and efficient cannery industry grew, although it lacked a product such as the anchovy.
Thus, during the s an anchovy preserving industry was established in the north of Spain, coinciding with an increase in the fleet of small fishing boats and steam launches. Moreover, in sea registrations had been abolished so there were no effective regulations over the number of craft and amount of unloading. In the first quarter of the 20th century an accelerated growth in anchovy exploitation flourished, but dropped sharply during the Spanish Civil War After the Protection and Renovation of the Fishing Fleet Act , the fleet of coastal fishing vessels was modernised and echo probes were introduced.
From this moment, anchovy captures reached a historical peak in the northern fishing grounds 81, metric tonnes in , becoming an extremely important socio-economic exploitation on the Cantabrian coastline. Figure 1. Development of anchovies unloaded in the fishing area 8 b, c Bay of Biscay from Since the historical peak, even though the effort has increased, the number of captures has reduced slowly with some variations as seen in Figure 1, until recently when, due to the alarming state of the stocks, the European Commission decided to stop the fishing July-September; between September-December the European Commission extended the fishing ban until 1st January ; on 20th July the Commission recommended a new ban.
These actions have caused a profound socio-economic crisis in the fishing and cannery sector in the north of Spain. It is a basic ingredient of sushi and sashimi, two traditional Japanese dishes. Although in daily meals fish of lower economic value is used, in special meals and banquets the maguzo red tuna in Japanese is served, as it is considered a delicacy.
The red tuna is a major pelagic predator which migrates to reproduce and feed. It is able to reach great speeds in propulsion, which allows it to exploit such diverse areas as the sub-arctic and the subtropical. It is restricted to the North and Central Atlantic Ocean. Another similar species is the red tuna of the south Thunnus maccoyii , found in the south Atlantic and Pacific, which doesn't acquire the reddish tones in its fat, compared to the former, which is so appreciated by the Japanese consumer.
The International Commission for the Conservation of Atlantic Tuna ICCAT is a regional fishing organisation with its headquarters in Madrid and is responsible for the management of red tuna populations and their fishing. Interestingly, red tuna fishing exploitation in the Mediterranean has been carried out since ancient times. Proof of this are the archaeological remains of the city of Baelo Claudia 2nd century AD, now Bolonia, Cadiz , whose principal industry was the production and exportation of garum, a type of fermented sauce made with tuna blood and fish remains which was very much sought after in Rome.
It is not known what technique was used to capture the tuna but, similarly to nowadays, it is believed that they waited for the tuna to pass through the straits, such as Gibraltar, or wherever it gathered in huge shoals for spawning. In contemporary times it has been fished using gillnets used since the Middle Ages, seine fishing, line fishing, surface longline fishing, driftnets now prohibited in the EU and live bait fishing.
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Apart from seine fishing, all the other techniques are passive, that is to say, they need the active participation of the animal in its capture, as opposed to this type, which actively hunts and captures great shoals where they gather during the spawning season. Although live bait fishing also searches for the shoals, in the end it requires the animal's own voracity to catch them. At the end of the 's, Spain constructed red tuna fish fattening farms for the first time on Mediterranean shores. These are based on maintaining and fattening wild tuna in captivity for a period of months.
This industry, as well as entailing a series of environmental problems dealt with in other chapters, has also meant a new impetus in the exploitation of red tuna in recent years. Thus, the fattened red tuna, in spite of being of medium quality, allows middle class Japanese families access to a very expensive product. This has extended the market and importation of red tuna in Japan, reaching an even greater volume than wild, un-fattened tuna, as can be seen in Figure 2 Japanese Importation of wild red tuna and of fattening farms, from the 5 principal exporting countries of the Mediterranean.
Source: Dr. Miyake data. The only fishing technique capable of transferring live fish to the fattening cages is the art of seine fishing. This itself raises other problems given the difficulty of controlling the numbers of fish per fleet, which tends to lead to a repeated problem of non-compliance with the total capture figure permitted by ICCAT.
Currently there are 12 countries on the shores of the Mediterranean with fattening farms, although Spain continues to be the main exporter. Due to the high financial profitability and major foreign investment in the poorer countries in the southern Mediterranean, there is strong political pressure to control the quotas assigned to each country and the total capture permitted by ICCAT.
This overexploitation results in low capture yields using traditional techniques, such as the hand line, the surface longline and even gillnets, which is affecting the traditional economy of many Spanish towns, mainly in Andalusia. What scientists are very clear about is that continued exploitation at current levels will lead to the west suffering a similar collapse in stocks as has occurred in the east.
When this happens, even heavy restrictions on fishing levels will not be sufficient to enable growth in the fish population. Other endangered fishing resources When speaking of fishing resources this usually refers, traditionally and erroneously, to only those biological fishing resources used by mankind.
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However, a broader and more correct definition would be: the biological resources, of commercial interest or not, which are used by or are profitable to man and which can be captured using any fishing technique, including all those species which may play an important role within the ecosystem. Therefore, any component of marine biodiversity susceptible to capture is a fishing resource in the strictest sense, since good conservation of an ecosystem's biodiversity favours fishing.