The mission of the Tuna Research and Conservation Center (TRCC) is to advance the knowledge and understanding of tunas, through research, education, and conservation. This mission is accomplished with a joint program that combines the resources and personnel dedicated to this goal from Hopkins Marine Station of Stanford University and the Monterey Bay Aquarium. The TRCC program draws upon the strength and excellence of both institutions, thus creating a unique hybrid between a private academic institution and public aquarium. Researchers, ranging from senior personnel (Barbara Block, Charles Farwell, Tom Williams) to undergraduate, graduate, post-doctoral fellows, research associates, technical staff, aquarists, and visiting scholars are all part of the TRCC program. In addition, a large contingent of dedicated and experienced fishers, scientists and volunteers help to carry out the field activities. The TRCC program provides a successful model for future partnerships between academic researchers and aquaria, zoos or museum personnel attempting to bridge programs with an emphasis on science, conservation and outreach.

At the center of the TRCC program is a unique facility, established at Hopkins Marine Station in September of 1994 for the maintenance of captive tunas. The TRCC personnel, in collaboration with aquarium personnel, maintain two large populations of tunas, one in the TRCC facility and one on exhibit at the Monterey Bay Aquarium. Currently over 150 tunas representing four species (yellowfin, Pacific bluefin, and two species of skipjacks) are studied at both locations. In addition, the ectothermic cousins of the tunas (mackerels and bonitos) are also in captivity for comparative study. The Monterey Bay Aquarium’s outer Bay window displays links to the natural beauty and superlative form of a school of tunas. In addition, the TRCC serves as a research center for basic biology of this family of fishes, with an emphasis on the development of tagging technology, physiology, biomechanics and captive husbandry. Researchers and students from Stanford, the surrounding Monterey Bay Institutions, as well as the international community are involved with projects at the TRCC on tuna biology.

The TRCC has also established an open ocean research program, called Tag-A-Giant (TAG), aimed at deploying sophisticated tagging technology on wild Atlantic bluefin tunas (Block et al. 1988a,b). The major objective of the TAG research program over the past years has been to collaboratively develop archival and satellite technologies with engineers, and to tag bluefin tuna in the wild to obtain detailed information on their migration and biology. To date over 600 electronic tags have been deployed in the open ocean. Most of our tag deployments have been implantable archival tags. The tags are miniature computers which are inserted into the fish. The tag wakes up every two minutes and collects data from sensors that provide information on internal body temperature, ambient temperature, depth and light intensity. From light intensity and corresponding estimates of sunrise and sunset times, it is possible to determine the geolocation of fish between the time of release and recapture. Depth and temperature data allow us to monitor behavior in relation to oceanographic conditions.

The second type of tag being deployed is a pop-up satellite tag. Over 200 have been placed in bluefin tuna across the North Atlantic. Our goal with the TAG campaign, is to implant 700 electronic tags on western Atlantic bluefin tuna by the year 2003. The objective of our tagging campaign will be to provide international management with a large data set on the migratory habits, breeding grounds, and mixing rates of western Atlantic bluefin tuna. The objective of the TRCC TAG conservation program is to provide the scientific data required to make appropriate management decisions about the species. We believe the intensity of the tagging effort and the resulting data collection are imperative for developing an appropriate management strategy which can ensure the future survival of Atlantic bluefin tuna.

In addition to the TAG program, TRCC researchers have used acoustic tags to follow yellowfin and Pacific bluefin tuna. These studies provided baseline knowledge of the temperature and ecological preferences of the two species that are at the core of the captive population. Pop-up Satellite tags have also been placed on Pacific bluefin tuna and albacore tuna providing the extensive measurements of depth preferences, migratory movements and ambient temperature preferences of these fish in the eastern Pacific. Electronic tags are opening a new window of understanding in the pelagic environment and scientists at the TRCC are using the tags to study the behaviors of blue and striped marlin and lamnid sharks (white sharks, salmon sharks).

A major new initiative called the Tagging of Pacific Pelagics is currently being organized with the leadership of the TRCC staff, and collaborators from surrounding institutions (NMFS, UC Santa Cruz). This program which is a pilot project of the Census of Marine Life will begin in 2003 and will provide the opportunity to examine multiple species in the North Pacific.

At the core of the Tuna Research and Conservation Center is the captive tuna population. The TRCC is a unique facility designed for maintenance of tunas in captivity. The facility consists of a 7500 square foot building that houses three holding tanks, each with its own life-support system. Two tanks hold 30,000 gallons (109 m3) each and one holds 90,000 gallon (327 m3). All are served by pumps, high speed sand filters, aeration/degassing towers and protein fractionator towers that provide high quality sea water at a rate of 400 and 1200 GPM, respectively. The design supplies water to each tank at 100% oxygen saturation at a temperature ranging from 20-25oC, a pH range of 7.8-7.9, and unionized ammonia at less than 0.01 mg/l. In addition to the TRCC facility the Monterey Bay Aquarium maintains tunas on exhibit in a 1 million-gallon capacity tank. The largest and oldest tunas in our collection are in this facility and remain part of the active research program. Data on feeding, growth and behavior our obtained from this collection of fish. The TRCC program has established the capacity to keep yellowfin tuna in captivity for over seven years with low mortality. Currently, 55 yellowfin spanning 7 year classes (15-150 lbs) are maintained between all tanks. In 1998, we succeeded in collecting our first Pacific bluefin tuna.. This involved the development of a new technique (an open-ocean sea pen) for collection and transport of our captive tunas. The use of a sea pen-based collection technique also provided a means of maintaining an accessible captive population of bluefin tuna at sea for experimental releases with instruments. Over 60 bluefin tuna now reside in the captive populations of the TRCC and Monterey Bay Aquarium.

Physiology and Fish Husbandry at the TRCC

Among of the most successful accomplishments of the captive tuna program at the TRCC are a variety of new handling techniques (stretchers, vinyl slings and mats) that have evolved to reduce stress when tunas are captured for sampling. In particular, obtaining blood samples has become a routine and reliable means for assessing a variety of physiological parameters including oxygen capacity, ion concentration and enzymatic function.

Additional information has been revealed from assessments of red and white muscle fat, myoglobin and aerobic enzyme concentrations. Citrate synthase is a key regulatory enzyme of the citric acid cycle and therefore plays a major role the aerobic production of ATP through the electron transport chain. Baseline studies with wild yellowfin tunas have established values that are similar to yellowfin in the early days of captivity. Interestingly, there is a strong trend between duration in captivity and loss of aerobic capacity. This tendency indicatesthat myoglobin content of white muscle declines with captivity in yellowfin tunas. This may be due to the lack of sprint activity during captive swimming. At the Outer Bay Waters tank in the Monterey Bay Aquarium, preliminary studies indicate yellowfin tuna maintained on a similar diet regime as the TRCC tunas in a significantly larger volume do not show the captive aerobic capacity effects.

Our Funders

Support for the research program conducted at the TRCC has been garnered from federal funding agencies (NSF, NIH, NOAA NMFS, California Sea Grant ) as well as private foundations and societies (Packard, Pew, MacArthur, Prothro Foundations, Disney, National Geographic Society). Both the Monterey Bay Aquarium Foundation and Stanford University contribute generously to the operation and support of the facility and researchers.