7132 ‎(2)‎

• UCREFRP Catalog Number: 7132
• Author: Jensen, B. L.
• Title: Culture Techniques for Selected Colorado River Imperiled Fishes.
• USFW Year: 1983.
• USFW - Doc Type: December 6-8, 1983.
• Copyright Material: YES

s
sprat at 10° is the same as in the Mediter- night in the surface zones of the water and
ranean sprat at 14-15°. does not feed during the day. The Falkland
sprat is a typical plankton eater and the main
3. The mean daily ration of the Falk- component of its food (80%) are large (10-
land sprat amounts to 6-8% of body weight. 18 mm) Euphausiacea.
The duration of the feeding of the sprat at
10° aunts to around 12 hours a day.
During the period of intensive fattening
(December-January) the sprat feeds at Submitted August 4, 1975
LITERATURE CITED
Barabanov, A. V. and L. V. Sherbich. 1975. Methods of determining age and natural mor-
tality of the Falkland sprat. Tr. Atlant. n. -i. in-ta morsk. rybn. kh-va i okeanogr. ,
27.
Borutskiy, Ye. V. 1974. Metodicheskoye posobiye po izucheniyu pitaniya f pishchevykh
otnosheniy ryb v yestestvennykh usloviyakh. (Systematic manual on a study of food and
food interrelations of fish under natural conditions). Moscow, Nauka Press.
Vinberg, G.G. 1956. Intensivnost' obmena i pishchevyye potrebnosti ryb. (Intensity of
metabolism and food requirements of fishes). Minsk, Belorussian Univ. Press. -1968.
Interrelationship of intensity of metabolism and rate of growth in animals. In:
Biologiya morya. (Biology of the seas), No. 15. Kiev, Naukova dumka Press.
Vinogradova, Z. A. 1967. Biokhimiya morskikh organizmov. (The biochemistry of sea
organisms). Kiev, Naukova dumka Press.
Kazanova, 1. 1. 1960. The biology and fishing of the sprat in the northern part of the Baltic
Sea. Tr. Vses. n. -i. in-ta morsk. rybn. kh-va i okeanogr. , 42.
Lipskaya, N. Ya. 1960. Daily and seasonal course of feeding of Mediterranean sprat
(S rattus sprattus phalericus). Tr. Sevastop. biol. st. , 13. -1967. On the assess-
menenergy expenditure on the formation of sexual products in fishes. Vopr.
fichtiol., 7, No. 6 (47).
Shkitskiy, V. A. and Yu. P. Nozdrin. 1969. On the question of daily vertical migrations of
the Baltic sprat S rp attus s rp attus balticus. Tr. Atlant. n. -1. in-ta morsk. rybn.
kh-va i okeanogr. , 21.
Peculiarities in the Manifestation of Certain
Defensive Reactions of Pelagic Fishes from
the Gulf of Mexico in the Area Fished
by an Electrified Bottom Trawl
Yu. M. Maksimov
Klaypeda Branch of the Special Experimental and Design Office of the Commercial
Fishing Fleet (SEKB)
The peculiarities in the manifestation of certain defensive behavioral reactions
of pelagic fishes (escape, optomotor reaction) when entering the electric field of
a trawl with parameters of a pulsed current f = 20 - 25 Hz; Ja = 4 - 6 kA; T = 1.6
msec are examined. An attempt Is made to explain some defensive reactions of
fish affected by an electrical field from the point of view of natural responses to
dangers encountered in nature. There is need to select such parameters for the
electric current and designs for the electrification of a trawl in order to neutra-
lize the manifestation of defensive reactions and increase the efficiency of
present trawling gear.
In a previous work (Maksimov, 1976) we
described the elements of the defensive be-
havior of pelagic fishes from the Gulf of
Mexico in the area of a non-electrified bot-
tom trawl. It was shown that the defensive
w behavioral reactions of fish are formed by
various stimuli, originating during the work
of the trawl, the principal ones of which
are: visual, hydrodynamic and acoustic.
It was established that as a result of the
action of this combination of stimuli a
school of pelagic fish perceive the trawl as
an orientational stimulus at the moment of.
entry and subsequently as a source of
danger. At the same time, in fish in the
zone of action of the trawl a combination of
behavioral defensive reactions are manifested
(escape, optomotor reaction, etc. ), causing
them to withdraw from the area or prevent-
ing them from being carried rapidly into
the codend of the trawl.
Now that electrotrawl fishing is being
developed, it becomes necessary to detect
defensive reactions under the action of an
additional stimulus, that of the pulsed elec-
tric current.
Works which are devoted to a study of the
behavior of fish in an ordinary trawl (Man-
teyfel' et al. , 1958; Vyskrebentsev, 1968,
1970; Ionas, 1960; Korotkov and Kuz'mina,
1972; Okonski, 1967) or which describe the
behavior and reactions of sea fishes in elec-
tric fields of laboratory aquaria (Danyulite,
1963, 1974; Danyulite and Prits, 1965;
Mal'kyavichus et al., 1968) have been pub-
lished. So far there are no works of a com-
posite nature, describing the defensive be-
havior and reaction of fish in an electrified
trawl. `
In the Klaypeda branch of SEKB of the
commercial fishing fleet, underwater obser-
vations were carried out during 1972-1974
on the work of electrified trawls. They made
it possible to select such parameters and de-
signs for the electrification of a trawl as
would ensure the neutralization of the above-
mentioned defensive reactions for 4-8 seconds
in almost all fish moving in the space between
electrodes. However, this represented a
considerable stage of research (1972-1973)
into the reactions and behavior of fish under
the influence of a pulsed current with a
304 305 ISSN0032-9452/77/0200-0305$07.50/0
© 1978 Scripts Publishing Co.