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Biological Control. Follow-Up Strategy for Further Studies of Beroe ovata Before Any Introduction Is Proposed

It is generally agreed that the most likely place to find a biological control species is in the home range of the pest. However, this may not be the safest procedure. FAO has recommended that a search for a control agent should first be done in the region of introduction for safety reasons. Experience in the Black Sea has shown that such control agents are not present there; therefore some thought it almost certain that endemic control agents will not be found in the Caspian Sea, while others disagreed.

A search for local control agents should be done. This research will be conducted in local laboratories. Experiments on the feeding on Mnemiopsis by Caspian predators is planned to be conducted in local scientific institutions.

At present, two non-native species have been identified as potential control agents: Beroe ovata and Peprilus triacanthus.

We regard Beroe ovata as the best potential biological control agent for short-term use. It is a highly specific predator of Mnemiopsis, and has been demonstrated to reduce Mnemiopsis populations in the Black Sea, after it was introduced there in ships’ ballast water. Research on Beroe should be directed to its ability to survive in the Caspian Sea. Since it is a specific feeder on gelatinous zooplankton, and there are no endemic gelatinous organisms in the Caspian Sea, it will probably have no direct effect on the endemic fauna. Some thought that possible effects on the endemic fauna could occur, although no specific examples were put forward. Research on possible effects of Beroe should go forward in scientific organizations in the Caspian countries.

Peprilus triacanthus has a great potential as a biological control agent as well, although this has not been proved as conclusively as in the case of Beroe. We regard Peprilus triacanthus to have one advantage over the use of Beroe, and that is that it will be useful economically (as a commercial object). Some doubted that it eats only gelatinous zooplankton. While Beroe reduces Mnemiopsis populations, it also creates a gelatinous food chain, with nothing of use to humans. The use of a fish holds the potential to convert some of this gelatinous material into usable food. The use of both Beroe and Peprilus would probably be even more advantageous, particularly if the fish eats Beroe, since Turkish investigators have found large blooms of Aurelia in the Sea of Marmora in the absence of Mnemiopsis.

Research Needs:

Experimental research on Beroe will be much less expensive than research on Peprilus. Work on Beroe can be carried out in small aquaria in most laboratories. This research will include:

  1. Ability to transport Beroe from the Azov Sea to the Caspian Sea,
  2. Ability to cultivate Beroe in Caspian water,
  3. Simulation of the entire range of Caspian environmental conditions in the laboratory,
  4. Interactions of Beroe with local plankton,
  5. Interactions of local fishes with Beroe,
  6. Interactions of Mnemiopsis and Beroe in Caspian water,
  7. Determination of optimal conditions for transport of Beroe to the Caspian region,
  8. Ability to cultivate large quantities of Beroe in the Caspian region.

As a result, the scientific justification for the introduction of Beroe into the Caspian Sea will be established. Introduction of the ctenophore into the Caspian Sea will follow a protocol that is agreed to by all the Caspian countries. Foreign funds may or may not be needed for this work. Experimental work on Peprilus will be much more expensive, and will require collaboration of foreign researchers. Thus, it will require both local and foreign funding. At this point, because of time constraints, our meeting was concluded, and there was no discussion of research needs for experimental work on Peprilus.

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