Finfish spoke with Professor Chris Bridges, one of the researchers responsible for closing the lifecycle of Atlantic and Southern Bluefin Tuna that has received much prominence and excitement in the global aquaculture community over the past year.

Professor Bridges is Group leader : Ecophysiology / Fish physiology at the Institute for Zoophysiology Heinrich Heine University, Düsseldorf Germany.

Chris is a fish physiologist who has been looking at the reproductive biology of bluefin tuna for over 10 years. The basics interests of his research group are to look at the adaptations of specific species to environmental factors. 

The group has developed specific assays for reproductive biomarkers in large pelagic species together with an array of ELISA tests for steroid hormones and specific reproductive markers such as vitellogenin and Zona radiata protein.

They are supported by a well funded biological tool room. The tool room experts have designed and constructed many of the devices used for implanting and managing the brood stock. Their work has also included the use of data loggers in monitoring brood stock behaviour and environmental variables within grow out cages.

Here’s a transcript of our conversation.

Welcome to Finfish Chris.

Andrew:  Chris, what was the key step that unlocked the ability for you to achieve the Tuna spawning breakthrough?

Chris:  I think the design and use of the implant system which was further developed in the REPRODOTT project together with the knowledge we obtained as a group of European scientists on the Biology of the Reproduction of Bluefin Tuna were really the basis of the present success of both the REPRODOTT and ALLOTUNA projects.

This experience and technology was also made available to the Clean Seas operation in Port Lincoln Australia where they were the first to obtain fertilised eggs in a land based facility.

The use of GnRHa hormone implants pioneered by the Yoni Zohar and Dinos Mylonas in other fish species has made a major contribution to the sustainability of a number of aquaculture species. 

This was combined with the development of implant tags by our group which could be used underwater without  the need to handle large pelagic species.

These tags ensured that the implant was placed correctly within the muscle tissue, that it was anchored securely and at the same time gave a visual indication of the depth of implantation and the identification of each fish. Further developments are now going on using Titanium provided by Thyssen-Krupp for the implants.

Andrew:  how long ago did you define the problem and begin a concerted effort that led to the solution?

Chris:    This goes back to the initial work started by the European commission funded project DOTT in 2002 which backed onto a previously purely biological  EU project BFTMED  in which we were involved to look at wild tuna populations.

DOTT was conceived to bring together many European researchers to look at the problems involved in the domestication of Tuna.

Following this project the REPRODOTT study then started in 2002 -2005 which involved a whole consortium of European countries with specialists in all fields of reproduction.

The successful conclusion of REPRODOTT with the production of fertilised bluefin tuna eggs in captivity in Mazarron in Spain in July 2005 after hormonal induction was a major breakthrough. 

These results were greeted enthusiastically by the European Commission and our commercial partners Tuna Graso. So much so, in fact,  that in 2007 in an open call for sustainable aquaculture projects in our next project SELFDOTT was recommended for funding by the referees.

At the same time, parallel to this work, the region of Puglia had decided to support the aquaculture industry with structural funds from the European Union and the project ALLOTUNA was conceived under the coordination of the University of Bari.

The breakthrough results of obtaining over 20 million eggs in the tuna farm of Mare Nostro last week in Calabria was due again to an international consortium of European scientists providing their expertise and know-how.  This concerted effort by European scientists supported by the tuna farming industry in Spain, Malta and Italy together with the European commission has made  this success possible.

Andrew:    what is your vision for how you would like to see the knowledge that you have created used?

Chris:  We see the role of our group in the development of new tools and techniques for use in the fisheries and aquaculture industry. This can be done by combining with the industry (such as Tuna Graso) to solve some of the bottleneck problems within tuna aquaculture.  At the same time however the sustainability of the fishery and/or aquaculture are of paramount importance at an ecologically viable cost.

Andrew: are you continuing your research in related areas?  Where next?

Chris: As I said above, new projects SELFDOTT and ALLOTUNA will continue to the next two to three years. 

We plan to extend our suite of analytical tools for studying the reproductive behaviour of tuna.

We are also combining our skills in terms of muscle biopsy sampling from live fish for genetically  fingerprinting and sex determination of brood stock.

We will also shortly be delivering a sex determination system based on Zona radiata protein antibodies to helping in the work of CSIRO in monitoring the Indonesian southern bluefin tuna landings. 

First you can see we have plenty to keep us busy for the future.

Andrew:     To your mind, what is the largest challenge that stands in the way of achieving sustainable aquaculture production on a global basis?

Chris:     Two major challenges are  already present within the aquaculture sector.  The first is the lack of space within the marine environment, especially the coastal environment for fish farming.  One of the most exciting possibilities is a movement to offshore fish farming perhaps in collaboration with the offshore wind farms such as those being proposed by the Blue-H  group. 

The second challenge of an ecologically viable aquaculture revolves around the use of pelleted artificial feeds and this is  indeed part of the remit of the SELFDOTT and ALLOTUNA projects.

Andrew:      Thank you for sharing your insights with us Chris.  The Finfish community wishes you well with your research endeavours and we look forward to staying in touch with you and your work.