Catálogo de publicaciones - libros

A brief description is made of the Atlantic bluefin tuna, (L.), from the point of view of its biology, geographic distribution and population dynamic. With the Strait of Gibraltar traps as a reference and providing a vision from ancient times to the present, scientific activities on this fishing gear are reviewed in an attempt to explain the reasons behind the crisis of the catches in this fishery, which began at the beginning of the 1960s and which has been extended until recent times. In order to do so and based on a recent publication on the issue, the Bay of Biscay fishery is presented as a fishery with a long tradition on which numerous scientific studies have been carried out and whose data are of great importance in the ABFT assessment group of SCRS (ICCAT’s scientific committee). Traditionally, the catches of this fishery have been made up of juvenile specimens (<40 kg) making up more than 97% in number of fishes according to a 62 year series studied (1949–2010). From an analysis of the population it has been shown that the impact of massive fishing of juveniles in this fishery between 1949 and 1962, together with that of juveniles in Morocco (the Atlantic part) possibly caused the decline of the traditional traps fishery of spawners in the Strait of Gibraltar and the collapse of the spawner fisheries in the north of Europe from the 1960s. This situation continued until 2007, the year from which a Pluri-Annual Recovery Plan (PARP) was adopted by ICCAT for the eastern stock. Since the PARP was implemented juvenile catches have disappeared from almost all the fisheries, a scenario that coincides with a considerable recovery of the spawning stock biomass in the eastern eastern Atlantic and Mediterranean, according to the results of the latest SCRS assessments.

Some characteristics of bluefin tuna are described relating to its biology (growth, reproduction, migrations and ethology), physiology, geographical distribution and fishing. Regarding the latter, the evolution of bluefin tuna fisheries over the last seven decades is analyzed, with descriptions of the various fleets working in different regions over this period.

The management of bluefin tuna resources within ICCAT is based on the consideration of two distinct stocks. A definition is provided of what a stock is from the point of view of a species subjected to fishing exploitation and the basic criterion by which the separation of bluefin tuna into western and eastern stocks was adopted.

Taking bluefin tuna in the Strait of Gibraltar as a reference, a description is made of the fishing methods used in its capture from the ancient populations of hominids to the present day. To do so, and based on recent paleoanthropological studies, the hypothetical way in which this fish would have been caught by the neanderthals is described (over 30,000 years ago); based on an extensive bibliography on the subject, the way fishing would have taken place in the Roman city of (200 B.C.) is described; and how it was during the Modern Age and is nowadays. Information is given on the fishing statistics from three Spanish traps between 1525 and 1756, upon which different scientists have pronounced in recent publications, and emphasis is placed on the overfishing that has taken place since the middle of the 20th century, its consequences, and how these have been overcome.

The Strait of Gibraltar is defined as one of the most emblematic places in bluefin tuna biology, and the traps installed therein are platforms without equal in the study of this species. The enormous literature available on his fishing gear makes it impossible to make a full description from the historical point of view in the present study; however, some of the scientific activities and scientific committees of the last century are cited, followed by a list of the most recent research projects on the species. Two symposia, held in 2008 and 2011, dealing with bluefin tuna biology and fishing are reported, the latter of which was exclusively dedicated to the traps fishery and the research carried out at these fishing installations.

The traditional fishing method for catching bluefin tuna in the Bay of Biscay used to be trolling, but in 1949 rod and live bait (bait boat) was introduced, which meant a great leap forward in the catches of this species. The different phases of fishing with this new system are briefly described as well how the fleet developed from the middle of the 20th century and the fishing seasons and type of fishes caught in this fishery.

This chapter reviews the research made on bluefin tuna in the Bay of Biscay fishery from a historical point of view. The subjects dealt with range from geographical origin, migrations from this area, conventional and electronic tagging, growth, and a compendium of studies on this fishery, are discussed. The ICCAT official statistics corresponding to landings, biological samplings (before and after the implementation of the PARP), the demographic structure of catches, and the abundance index of juvenile fishes are also considered.

Up until now we have seen the contribution of the ABFT Bay of Biscay fishery to the eastern stock from 1949 to the present highlighting that there is a before and an after of the PRPA. We shall proceed to look at how this fishery has influenced the remaining eastern Atlantic fisheries.

The traps that catch bluefin tuna in the Strait of Gibraltar have provided work, wealth and food for thousands of years, and are additionally a bottomless source of information for historians, scientists and the public in general. Fishing for this species both in the Atlantic and the Mediterranean has always been sustainable, no written testimony ever having certified that human intervention had affected the overexploitation of the species. But that all changed at the end of the 1940s following the Second World War when new fisheries began to develop in the Atlantic. The main ones were those of northern Europe, mainly in Norway, with the introduction of purse seine, in which spawners were caught, and in the Bay of Biscay mainly targeting juveniles. In 1958 purse seine fishing for juveniles began in Morocco (the Atlantic part).