Original publication: April 2015
Authors: PROBITEC, Spain: Luis Ambrosio, Pablo Xandri
Short link to this post: http://bit.ly/2HnaRCK
The traditional fishing method called almadraba is one of the oldest recorded fishing systems, and is currently the object of study by anthropologists, sociologists and economist as a clear example of human activity developed to follow recurring migration cycles – specifically those of the Atlantic bluefin tuna (Thunnus thynnus). The almadrabas catch tuna as they swim across the Gibraltar strait, the Atlantic Ocean and the Mediterranean Sea when they go to spawn, and until recently, on their return (“al revés”) journey when they return to the Atlantic Ocean. Besides this species, they also catch bullet tuna (Auxis rochei), little tunny (Euthynnus alletteratus), Atlantic bonito (Sarda sarda), bigeye tuna (Thunnus obesus) and swordfish (Xiphias gladius). The almadrabas that are used to catch tunas during their seasonal migration from the Atlantic Ocean to the Mediterranean Sea are called “di corsa” in Italian and “al derecho” or “de paso” (all these words translate to mean ‘forward’ in English) in Spanish. In Italian these are called “di ritorno” and “retorno” or “revés” (‘going back’, ‘the return’ in English). These traps catch the tuna when they are moving towards the Atlantic Ocean (trophic migration), with the outside net orientated towards the east (levante). The basis of this fishing method is that the schools of tuna, upon encountering the nets (called “raberas”), do not try to go through them, but instead they follow them, enter inside the labyrinth of nets and continue through the diverse chambers of nets, finally trapping themselves inside the final chamber, called the “buche”. The fishing season for the “paso” almadraba traps begins in the spring and ends at the start of summer, and the season for the “retorno” almadrabas begins at the end of summer and ends in the autumn.
The long story of the almadraba traps has given us a series of data that is of important scientific value. These days, by performing a multivariable analysis, it is possible to specify how different factors have influenced the fishing of tuna. At this time, environmental factors could have a greater influence on the population than the fishing catches themselves. The almadraba technique used for Atlantic bluefin tuna fishing is respectful to the environment and to resources, due to several characteristical factors of this fishing system including: seasonality, location, structure, low energy consumption because of its working system, lack of waste generation, there is a limited stay time for the tuna within the structure of the almadraba, it creates a very reduced “bycatch”, because the structure uses large mesh nets, and the small percentage of caught tuna correspond to adult specimens that have already bred and have spawned on several occasions, and the size and flexibility of the nets mean that there is no damage to the cetacean or dolphin populations and it doesn’t have any influence on the local hydrological dynamics.
Nowadays there are 4 countries that practice fishing using the almadraba technique: Spain, Italy, Morocco and Portugal. The working system in all countries is similar. The number of jobs per almadraba is an average of 43 people, compared to 10 jobs on a purse-seiner dedicated to the fishing of bluefin tuna in the Mediterranean Sea, 10 jobs on a surface longliner fishing in international waters, or just 6 jobs on other longliners.
Almadrabas don’t have great significance on the Spanish fishing sector. In the province of Cádiz there are currently four almadrabas dedicated to the fishery of Atlantic bluefin tuna. From these, the four of them (Tarifa, Conil, Zahara de los Atunes and Barbate) are on “de paso”, and until very recently the almadraba in Barbate “de retorno”. During 2013 in Spain 1,369.98t of tuna were caught using almadraba, which means an increase of 67% against the 819.76t in 2006. This increase is due to the purchase of quota from other sectors of fleet, as this has been kept fixed at 657t. It is one of the few fishing systems that generates stable employment, regulated by a labour agreement.
Currently there are three licenses for the almadraba fishing method in Sardinia: Isola Piana, Portoscuso and traps Porto Paglia. But due to the small quota, only two of these are set up, and it creates employment for 105 people. The break-even point estimated for each almadraba is 100,000 kg per season/almadraba, and now there is a quota of 165t for all the Italian almadraba traps, which catch 222t (2013). In 2010 approximately 40% of the production of the almadrabas in Sardinia was designated for the local market, 30% was for the European market, 20% for canning products and only 10% was exported to Japan.
Currently there are 3 almadraba traps in Portugal, located in the Algarve region, mainly focused on catching Atlantic bluefin tuna. The only legally allowed technique in Portugal for the fishing of bluefin tuna is the almadraba, and using this technique the catches generated 233.19t of fish in 2013. There is the possibility, with the supervision of the fishing administration, of using them for tuna fattening.
In 2013 there were 10 almadraba traps installed in Morocco, all of them in the Atlantic Ocean waters, and these caught 960.47 t (2013). The period of activity has generally been from April to July, but with the reduction of quotas, the period of activity has been mainly confined to May.
Consultations with companies in this sector show that staff costs in Morocco are 20% lower than in Spain, which as consequence has meant that European companies have chosen to base themselves in this country.
The trend is to organise into cooperatives and to vertically integrate the almadraba traps concession holders, in order to improve the appreciation of fishing products, and to establish a unit of industrial processing to decrease the amount of tuna exports in a raw state, taking better advantage of the periods when the tuna catches take place, as well as in looking for mechanisms like the sustainability certification of the fishery to provide the products with greater added value.
The results highlight that the almadraba traps provide valuable scientific information about the population of bluefin tuna across time, and the scientific community agrees to use them as observation points of bluefin tuna populations. After the last CCAT meeting held in Genoa, increments of 20% to the annual quota until 2017, were passed, leaving the possibility open for upward revisions. The catches reflect an increase in volume and average weight. The sector of almadrabas suffered greatly from the reduction in quotas in 2008 and expects to get compensation for that effort, as well as to avoid mistakes in the future that were made in the past.
“Almadraba” must be considered as a useful tool for the management of the BFT fishery. Some of the best EBFT size/age-at-catch historical datasets are to be found in the archives of coastal Mediterranean trap set-net. No other fishing gear in the history of mankind has proven itself to be as sound, efficient, selective and yet so sustainable and environmental-friendly; moreover and for the purpose of this study, so well documented and almost fully traceable. Also, the “almadrabas” have remained for the past four centuries and still today, an invaluable ‘data gold mine’, while, on the other hand, fishing mortality due to them remains low and the sizes of EBFT caught by such traps is close to the optimum, in terms of yield per recruit.
The data of the traps provides high-quality age-specific biometrics of stock biomass, for both the sedentary and migrating fraction of the EBFT stock, as well as a wide range of biological data that constitutes an invaluable component in the EBFT stock assessment models.
In reference to stock status, the analysis on the status of EBFT populations carried out by the ICCAT-SCRS in 2006 and 2009 (ICCAT, 2007; SCRS, 2009) pointed out to a rapid deterioration of the Eastern Atlantic stock.
Because of this situation, was established a EBFT Recovery-Plan (enacted by ICCAT Recommendations: 06-05-BFT to 13-07-BFT), which evolved around a number of stringent management measures: Fishing-fleet reduction, the banning of aerial tuna-spotting, real-time reporting, the BCD scheme, onboard observers, the contraction of fishing seasons, quotaslashes, fisheries policing both at port and at fishing grounds, war against IUU EBFT trade, etc.
After this and according to ICCAT-SCRS latest 2014 updated EBFT stock assessment, results indicated that the spawning stock biomass (SSB) showed clear signs of sharp increase in all the runs that have been investigated by the SCRS-ICCAT accepted a general scientific precautionary approach to sound fisheries management that would rely on trustworthy accurate and comprehensive EBFT size/age-at-catch historical datasets.
Link to the full study: http://bit.ly/540-367
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