Michael Blenk Mexican bluefin tuna ranching. Ecological Aquaculture Studies Reviews. University of Rhode Island, Kingston, R.I.

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1 1 Michael Blenk Mexican bluefin tuna ranching. Ecological Aquaculture Studies Reviews. University of Rhode Island, Kingston, R.I. Abstract Capture-based aquaculture is being used to raise Pacific bluefin tuna (Thunnus orientalis) in net-pens off the coast of Baja California, Mexico at four farms, with more permits and farms coming. Purse-seines are used to capture wild juvenile bluefins to be raised in net-pens close to shore. Wild Pacific sardines (Sardinops sagax caeruler) are harvested from local Mexican waters and are fed fresh to the tuna giving them a high meat quality. Tuna ranching is creating good jobs for Mexican coastal communities and restoring jobs to sardine and tuna fleets. Japan plays a large role in the global tuna market and is the primary buyer of Mexican tuna. Bluefin tuna and Pacific sardine populations are under constant pressure and tuna ranching relies on natural populations to function. In the future Mexican tuna ranching may evolve into tuna farming with the closing of the bluefin lifecycle, but tuna ranching has a huge potential for growth in Mexico due to its relaxed laws, favorable environmental conditions, and easy access to wild stock and feed. Introduction Mexico has joined the exclusive group of tuna ranchers. Tuna ranching of wild caught tuna is among the fastest growing forms of aquaculture in the world. It is estimated that 80% of tuna will come from aquaculture in the future (Doumenge, 2001). Along with Japan, Australia, the Mediterranean, and Canada, Mexico is now contributing approximately 10% of the global tuna production (Zertuche, 2006). The fish Mexico has chosen is the Pacific bluefin tuna (Thunnus orientalis). The Pacific bluefin is a valuable fish with an already existing high market price, where $45 a pound at the Tsukiji Fish Market in Japan is not uncommon (Van Patten, 2006). Not only does tuna fetch a high price, but there is an accelerating demand. In 2005 Japan alone imported 35,000 tons of ranched tuna (La Madeleine, 2006). Japanese demand for bluefin tuna is at an all time high, and tuna is the second-most popular seafood in the United States (Van Patten, 2006). Mexican tuna ranching is not true aquaculture. A true aquaculture farm would raise tuna from egg to market without using wild tuna to stock their farms. Tuna ranching uses fishing boats with purse-seine nets to catch wild tuna that are roughly two years old as the schools reach Mexican waters. Fish are towed back to shore in the nets and transferred into large pens where they are fattened with locally caught sardines until they reach market size. Mexico has great potential to become the Mecca of tuna farming. Mexico has suitable water temperatures, naturally occurring tuna and feed stocks near shore, and relatively flexible laws that governing the development of nearshore aquaculture.

2 2 Tuna and the Community In the early 1900s white fleshed tuna began to be marketed as an alternative to chicken. San Diego and Baja California soon became hubs for tuna fishing and canning to support the new market. Rising labor costs and the development of tuna-industry dolphin-safe standards in the 1980s nearly halted the Mexican tuna fishery, sending boats to the far western Pacific waters of American Samoa and Guam (Hoffman, 2007). Due to the large bycatch of dolphins by purse seine net tuna fishermen, the United States placed an embargo on Mexican tuna. Thousands of Mexican fishermen lost their jobs and Mexico lost more than 44 million dollars from the export of about 30,000 tons of tuna (Buenrostro, 1999). The embargo was lifted in 1997, but the damage had already been done to the Mexican fishing fleet. The West coast of Mexico has a large yellowfin tuna fishery, as well as skipjack fishery. The yellowfin fill a crucial niche of providing tuna for the canned tuna market. However, when yellowfin can t reach quotas bluefin can be used to fill in the rest, adding to the bluefin deficit. (Doumenge, 2001) Many Mexican fishermen have turned to harvesting sardines for canneries, and tuna ranching creates a need for even more sardine fishing jobs (Sylvia, 2007). Tuna populations rely on sardine stocks. If sardines are not harvested in a sustainable manner, not only will there not be enough fish to economically feed penned tuna, but without sufficient sardine populations juvenile tuna may not even migrate to Baja California to be ranched and fattened. Tuna ranching is now a possibility for the people of Ensenada, and other Mexican coastal communities. But why would they want to participate in tuna ranching? Minimum wage in Baja California is pesos a day (CIA World Fact Book, 2006). An unskilled agricultural laborer will make minimum wage. An unskilled laborer working at a Mexican aquaculture facility receives 500 pesos a week. Technicians with a university degree receive 5,000 pesos, or $457 a month, while a biologist earns 20,000 pesos a month, which translates to about $1830 (DeWalt, 2002). While most employees would be at the lower end of the payroll, a job at an aquaculture facility is a better alternative to many of the low paying labor jobs of the region. As many Mexican fisheries collapsed, tuna ranching moved in and is giving the fishing community another chance to work the waters. Technical Aspects Mexican tuna aquaculture is different than the farming that takes place with many other species of fish. Ideally, the lifecycle of Thunnus thynnus will one day become closed and bluefin tuna will be raised from egg to market product in captivity, but as of now Mexico must capture its stock from the wild. Japan claims that it has facilities that have closed the lifecycle, but these practices can t economically compete with the capture-based market at this time (Sawada, 2005). Tuna ranching has taken off in Ensenada, Baja California. Enter Charat, a French-born Mexican citizen left a shrimping business on Mexico's Gulf Coast and began fishing tuna out of Ensenada in In 1997 Charat established Mariculture del Norte. Located in Bahia de Todos Santos, Mariculture del Norte was the first and most successful tuna

3 3 farm. Last winter Mariculture del Norte fattened more than 1,500 tons of fish in two dozen pens anchored in a hidden cove tucked around a point of land south of Ensenada harbor. With more than eight other permitted farms, Mexico produced 3800 MT of bluefin tuna in (Hoffman, 2007) The ranching process begins by leasing an area of ocean from the government that is protected from storms but still has a large tidal prism to disperse the wastes of the fish. Once a site is approved for aquaculture, there is a large amount of necessary equipment. Tuna farming requires boats, purse-seines, towing nets, holding nets, feed, divers, workers, tuna stock and more (Sylvia, 2007). Capturing Tuna Mexico relies on wild bluefin populations as stock for its tuna aquaculture. The typical catching season lasts from July to September, depending on when and how long the fish reside off the coast of Ensenada. Purse-seiners will travel 30-50km offshore to find schools of tuna. The largest schools are typically two year old kg tuna and are targeted for capture (Sylvia, 2007). Once a large school is found the boat will circle the fish laying out a purse-seine net that hangs in the water column from floats on the surface of the water. Once the net surrounds the fish the bottom is pulled closed and the fish are trapped in the net. The net and fish are then pulled up next to a towing cage used to transport the fish to the holding site.

4 4 Purse-seine capturing bluefin tuna (upper left). A tow-net(upper right) towing the tuna back to the growout site (below). Divers are used to manually open gates in the nets and herd the fish into the towing net. The school of fish is then slowly towed at 1-2 knots back as far as 50km to the growout site. From this moment on the tuna are treated very carefully to increase their value. Fattening Tuna At the growout site the tuna are herded into permanent holding cages where they will remain for 4-8 months or longer. Tuna are divided into many holding pens. The pens are circular with a 30-40m diameter of pontoon floats and 60-90mm mesh nets that are12-20m in depth hovering 5m from the bottom. Cages can be stocked with fish per cage (May,2002). Stocking must be done carefully to not overcrowd. Bluefin are adapted for high speed and must continuously swim. If a bluefin doesn t move its body

5 5 length every second it won t get enough oxygen and risks suffocation (May, 2002). An outer mm mesh predator net is placed around the inner net. The predator net acts as a barrier to keep sea lions, sharks, and other predators from eating and stressing the tuna. A freeboard net is used to prevent the powerful tuna from jumping out of the cage. Many cages also have a handrail 1m above the circumference of the cage making working around them easier. Each net must also have screw anchors placed into the sediment to hold the net in place. All together each cage will cost $80,000- $200,000.These cages provide huge amounts of volume and with stocking densities of 4kg/m³ some cages can hold over one thousand fish (Aquaculture SA, 2000). With water temperatures ranging from C, feed conversion ratios are about 12:1 (Sylvia, 2007). Mortalities have been reported to be 2% over 6 months (May, 2002). The object is to take an average wild tuna and turn it into a much larger tuna with a high fat and oil content. Mexican tuna ranching has two goals. Yes, it is important to grow the tuna to a larger size, but more important than size is meat quality and fat content in the flesh. The tuna are fed large amounts of sardines three times a day, six days a week. One day a week the fish aren t fed so that damage isn t done to their liver from overfeeding. A broadcast feeding technique is used where the sardines are thrown over the entire surface of the cage. The broadcast feeding technique is used to increase food availability over a large portion of the pen s surface to prevent tuna from injuring each other while fighting to feed, and to promote tuna to swim around and keep their muscles in good condition (Apple, 2006). Pacific Sardines Sardines, like the tuna, are wild caught. Pacific sardines (Sardinops sagax caeruler) are in the clupeid family and can be found off the Pacific coast of North America from southern Alaska down to Baja California. The highest abundance of Pacific sardines occur in the waters off of Ensenada and are heavily fed on by the migrating tuna (Baumgartner, 2000). Trawlers are sent out to collect fresh feed for the tuna. Mexican tuna farms have the ability to feed their tuna fresh sardines, anchovies, and other clupeids from wild populations that naturally occur off the coast of Mexico. By feeding the tuna fresh oily sardines without the tuna swimming for miles chasing its food, the tuna s meat becomes an oily, rosy red, marbled with fat, increasing its quality and making it worth more money. The key to Mexico's success lies in the abundant supply of sardines which entice both the relatively rare dark-meat bluefin to the more common white-meat albacore and yellowfin that fuel the canneries. Harvesting and Sale The final stage of Mexican tuna aquaculture is harvesting and selling the product. Unlike the tuna fishery that must sell its tuna catch once it reaches the dock, farmed tuna can be sold whenever the market is best to make the most profit. Tuna farmers carefully watch the Japanese tuna market. 95% of Mexican farmed tuna goes to Japan, with half of that going to the Tsukiji fish market. The other 5% of tuna goes to West coast United States restaurants, and is of significantly lower quality (Apple, 2006).

6 6 Tokyo-Tsukiji fish market Before harvesting a group of tuna, they are isolated into smaller groups of a dozen or so to lower the risk of fish injuring each other and degrading the meat. A net is brought up below the fish and divers grab individual tuna holding their tail and gills. The divers pass the fish to a barge where the fish is quickly killed with a spike through its head, similar to a beef slaughterhouse. The fish is bled by severing a main artery in the gills and a fine steel wire is run down the fish s spinal cord to paralyze it and prevent flopping. The gills are cut out and the carcass is dropped into a 0 C saline water solution. The entire harvest and slaughtering process is done extremely fast to keep the tuna meat in the best condition. If the fish become too stressed lactic acid will build up in their muscles and degrade the flavor. If the fish are allowed to flop around they can bruise their meat. If they swim strenuously they can burn their meat due to their rete mirabile circulatory system. Once the fish are cleaned, weighed, tagged, measured and cold-packed they are driven across the boarder to The Los Angeles International Airport and flown to Japan, arriving the next day. The Japanese refer to the tuna coming from Mexico as laxfish because they are flown out of LAX airport and are known to have high quality meat. Problems with Tuna Ranching Although bluefin tuna farming is very different from other forms of aquaculture, it still shares the same problems of disease, waste pollution, predation, etc, that cage culture entails. However, there are many concerns that are unique to Mexican tuna farms. Both a blessing and a curse, Mexico uses wild tuna and sardine stocks to make their tuna farming possible. This means they rely on two fluctuating, unreliable, and troubled fisheries. Variation from season to season from weather patterns and fish behavior comes with the territory, but a much more serious concern starts on the other side of the Pacific. Before the bluefin migrate to Mexico, they occupy the waters off the coast of Japan. Japan has an enormous appetite for tuna and has a large bluefin fleet, as well as extensive bluefin aquaculture. Japan already claims a large chunk of the Pacific bluefin populations for its own needs, it is not impossible that one day in the near future Japan s needs could grow to a level where only a few bluefin even reach Mexican waters. Any number of

7 7 other reasons could cause wild bluefin stocks to drop, with many people claiming wildcapture aquaculture itself hurts the bluefin population. It is unknown if wild-capture aquaculture hurts wild stocks. From one view you are taking juvenile bluefin which will deplete the stock further. From the other side it is clear that tuna aquaculture will relieve fishing pressure on the adults of the wild population because aquaculture is filling a portion of the market demand. Tuna stocks are not the only concern. Sardine populations are just as important. Tuna require large amounts of food, and even more if you want to grow them quickly. If anything were to happen to decrease the number of sardines off the coast of Baja, Mexico, not only would feed prices skyrocket and an alternate feed would need to be substituted, but the tuna would grow slower and lose their oil content and red color, causing a decrease in meat value and more money lost. Pollution and waste is very high on tuna facilities. High intensity feeding of sardines results in an excess of sardine flesh entering the environment. Birds eat a considerable amount of the sardines fed to the fish, but this only causes an alarming amount of bird feces entering the water. Fish wastes are also frightening. Tuna are large animals and produce lots of wastes. And remember, the emphasis of tuna ranching is not put on growing, but on the level of fat in the flesh, resulting in very low food conversion ratios. So this means that there is a lot of organic matter not used by the fish which is released to the environment. Opportunities for Tuna Ranching Mexican tuna farms are faced with some regulations. Mexico doesn t like to share its regulatory information with other countries, but ProPeninsula, an organization dedicated to conserving the ecosystem of Baja California, reports that new tuna farms are only permitted to have three 40-ton-per-annum cages, and expanding limitations are 50 hectares of surface area. However, Mexico can be quite liberal with their laws and fail to enforce them. There are tuna farms in Ensenada that already have up to 1,100 hectares and no regulatory quotas. In fact, many tuna farms have extra unclaimed net-pens folded up already in the water standing by in case there is a large tuna catch. It is Mexico s relaxed government and high profits due to wild-capture techniques that have allowed tuna ranching to flourish in Ensenada giving great potential for growth and expansion to the rest of the Mexican coast. Seaweeds and mussels should be used to deal with wastes, ammonia absorption, and filtration. Integrated multitrophic aquaculture practices are sustainable and ecologically friendly. Longlines of Laminaria or Porphyra could be placed in the nutrient shadow of the farm and could be sold with the tuna to Japan for nori. Both seaweeds and mussels will improved the water quality by taking up nutrients, and create a secondary source of income.

8 8 Concern has been raised claiming that ranching hurts tuna populations just as much as fishing. In the wild, mortality of Pacific Bluefin tuna is between 20% and 30%. In the farms the losses are 2% over 6 months; so ranching utilizes the tuna population better than fishing (May, 2002). Tuna farming is still a relatively new practice and the best methods are still being determined. Mexican tuna farms are turning huge profits by using wild-capture juvenile bluefins and feeding them wild-caught sardines, so it is unlikely they will change their practices if they can be continued. From an environmental view Mexico should try to adapt a true aquaculture approach and follow the Japanese methods and close the bluefin lifecycle by creating tuna hatcheries. By practicing true bluefin farming they would spare wild tuna from being harvested and preserve bluefin populations. A formulated feed for bluefin with a good food conversion ratio would help cut down the harvest of local sardines and prevent fishing down the food chain. But even with business as usual there is great potential to increase production at existing farms and expand with more farms in Mexico. "They said it could not be done in Mexico because the water was too cold, the area of the fish migration too big," said Charat. "Now it's by far the most active thing going on in the region as far as fishing goes." (Hoffman, 2007) References Apple, R.W. How to Grow a Giant Tuna Aquaculture SA, Farming of Southern Bluefin Tuna Baumgartner, Timothy. Scripps Institution of Oceanography and CICESE, San Diego Natural History Museum Buenrostro, Gustavo. ENSENADA: El Puerto del Atun CIA World Fact Book, 2006 DeWalt, Billie et al. Shrimp Aquaculture, The People and the Environment in Coastal Mexico. Island Press Doumenge Francois. Pacific Fishing, August 2001 Hoffman, Allison. Tuna Farms Reviving Fisheries. Associated Press. April 3, 2007 La Madeleine, Bonnie. Casting our nets too wide: should tuna farming practices be more strictly regulated?. Japan Inc. Feb May, Jackie. Feedlots of the Sea. Earthbeat 2002 Sawada,Yoshifumi et al. Completion of the Pacific bluefin tuna Thunnus orientalis life cycle. Aquaculture Research 36 (5), March 2005.

9 9 Sylvia, Paula. Current Status of Bluefin Tuna Farming in North America. World Aquaculture Society Van Patten, Peg. Cox, Monica. Say Hola to Tuna from Mexico! Wrack Lines 6: