FISH LOGISTICS: THE KEY TO SUCCESSFUL CLOSED CYCLE TUNA AQUACULTURE

Introduction

Next Tuna GmbH is planning, the first of its kind, production facility for Atlantic Bluefin Tuna (Thunnus thynnus) (ABT) at the shore of the Mediterranean Sea. (see as well https://www.nexttuna.com/)

Tuna in general and specially ABT is very sensitive to handling. In the early live stages, the small fish are nearly impossible to touch, and at later stages, the fish are simply too big to be handled in a meaningful way.

Thus, internal fish logistics in the Next Tuna juvenile production concept becomes the main challenge to successfully produce ABT juveniles to a size of 2-10kg where they can be supplied into the existing Tuna fattening industry (see Fig.1).

In this contribution we want to present and discuss two novel approaches to internal fish logistics for tuna:

1. Internal transport in the hatchery by moving the entire tank around with a portal crane.
2. The use of floating RAS to facilitate transfer of the fish to transport net-pens, departing to Next Tuna customers.

Solution

Hatchery internal transport by crane:

For its hatchery operation, Next Tuna decided for movable tanks. The weaning and pre-growing tanks of Next tuna are planned in a way, that the whole tanks can be moved using a 40-tone overhead crane (Fig. 2). The bottom of the tank is equipped with an over-dimensioned bottom outlet to slowly release the fish. This avoids physical handling of the fish and adds a lot of flexibility in regards to fish density control. Another benefit of multiple movable units is a modular approach that will make it easy to refurbish and improve the systems for the specific needs of this species.

Transport of ABT to customers:

The second challenge is the transfer of fish from the hatchery into the production unit and from there the delivery to customers. Here Next Tuna has identified floating RAS systems as the most suitable solution to overcome these logistic issues (see Fig. 3).

Floating RAS offer the advantage of land-based systems as long as they are connected to land, and in addition they offer the flexibility that they can be moved to the hatchery when loaded with juveniles, or joined with transport cages when fish are delivered to customers.

For fish delivery, the floating RAS is connected to the transport cages, comparable to the technology applied for fish transfer from one net-pen to another. Like this, the fish transfer from inside the RAS to the transport net-pen can be facilitate through a gate in the floating RAS side wall.

Discussion

Next Tuna wants to present these novel approaches to fish logistics to the audience and discuss the chosen solutions and their implications with the experts present at the conference.