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Research Says Fish Remember for Months

ISRAEL - An innovative method trains fish to come to an acoustic signal source in order to eat and thus be caught.

Innovative research by the Technion’s Faculty of Civil and Environmental Engineering, which was presented at the joint annual conference of the Israeli Society for Soil Sciences and the Israeli Society of Agricultural Engineers, lays to rest the opinion that fish have a short memory span of only three seconds and demonstrates that fish actually have a memory span that lasts four to five months.

Based on this, researchers are developing sophisticated, new technologies to raise fish in coastal areas which rely on training them to respond to audio signals.

Today, raising fish in the sea is done using cages placed in sheltered coastal areas. This method is widespread in the world and involves investing in cages and service rafts, as well as the manpower required for constant monitoring of the cages and feeding and collection of the fish.

This method is controversial because of the environmental pollution that arises from the release of nitrogen by the fish. In various regions of the world, raising fish in cages has been completely banned due to fear of harming environmental quality.

The aim of the research, which was carried out in the Institute of Agricultural Engineering in the Agricultural Research Organization, is to find a new technological possibility applicable to raising fish in the open sea but without harming the environment and while maintaining profitability for the ranchers.

The proposed method is based on training fish in captivity to collect in the direction of a loudspeaker broadcasting acoustic signals in the water and to connect this with food. Through the connection between the signal and feeding, the fish develop classical conditioned memory. After a month of training in a closed facility, the fish are released into their natural environment – the open sea. After that, connection with the free fish in the open sea is maintained by periodic broadcasting of the signals to which they have been accustomed in order to preserve conditioned memory. When they reach market size, the fish are “called” to the collection station using the signals they are familiar with and are caught.

The use of acoustic signals in the sea enables control over large areas and turns the coast region into a ranch for raising fish.

Boaz Zion, Ilan Karplus and Assaf Barki presented the research at the conference and said that “the method has many advantages. The fish grow in their natural environment without the use of cages and without environmental pollution. Feeding is more economical and is based mainly on food found naturally in the living area of the fish.”

The conference on the topic of “Soil, Environment and Agriculture” was a joint endeavor of the Israeli Society for Soil Sciences and the Israeli Society of Agricultural Engineers. Some 120 persons from all over the world took part. Some 30 new research papers were presented and in addition, 28 posters of students from the Technion, the Hebrew University (the Faculty of Agricultural, Food and Environmental Quality Sciences in Rehovot), Ben Gurion University, and Tel Hai College were displayed.

Prof. Avi Shaviv, head of the Division of Environmental, Water and Agricultural Engineering in the Faculty of Civil and Environmental Engineering at the Technion, welcomed those attending the conference and said that: “problems in agriculture, water and environment in Israel and the world over the past few years have become very relevant and only by intelligent integration of the engineering and scientific aspects can we ensure sustainable and responsible coping with these problems.” In addition, he noted that after a long period in which the prestige of agriculture and water declined among the young, there is now renewed interest in subjects connected to water, agriculture and the environment. This has led to almost a doubling in the number of those registering for these fields at the Technion and, as much as he knows, also at other institutions.

the Fish Site Editor

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