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<br />and followiDg exposure for 60 sec to a field
<br />-.ith a streDgth of 38. 0 v/cm it was 10 %.
<br />Death from the effect of an alternating curreDt
<br />occurred ID the species of aquatic iDvertebrates
<br />investigated at electric field strengths of
<br />
<br />betweeD5. 2 aDd38 v/cm, which is 15-126times
<br />greater than the possible field strength of the
<br />electrified trawl.
<br />
<br />Submitted May 20, 1969
<br />
<br />LITERA TURE CITED
<br />
<br />Ki . henk M Ya V P Mikheyev and Ye. P. Shtern. 1963. The effect of an electric c~reDt
<br />rplCon D~~iss~na .l~v~ .and planktonic crustaceans following short expos~re. Tr. In:-ta blOl.
<br />vnutr. vod Akad. Nauk SSSR, No. 5(8) (Volume title: Collected matenals on the blOlogy
<br />and hydrology of the Volga reservoirs), Leningrad, Nauka. . .
<br />NuseDbaum, L. I. and T. I. Faleyeva. 1961. A study of the behavior of a. fish iD an electriC field.
<br />Izv Gos D -i in-ta ozern I rechn. rybn. kh-va, 52, No.1, Lemngrad.
<br />Sh ........ V.A' 1964 PresDo~odnyy elektrotralovyy lov ryby s primeneDiyem peremennog?
<br />eD'3_ov, .. . . t) M Pishchepromlzdat
<br />toka (Electric trawling in fresh water usiDg alternatmg cur~en. oscow,. . f he.
<br />Halsband, E. 1959. The effect of pulsating electric current on fish. Modern FIshmg Gear 0 t
<br />World. London. Fishing News (Books). .' . hen
<br />Kede! D 1955 Wer eiDe eventuelle BeeinflussuDg der y,schnahrtlere durch den elektnsc
<br />I Strdm unte~ besonderer BerUcksichtigung des elektrischen Fischfanges mittels fliesseDden
<br />GleichstromsZ. Fischerei. B. IV, N. F., H. 3/4. . . 1 d
<br />Vibert, R. 1967. General Report of the Working Party on t~e.Applications o~ E~ectnclty to In:
<br />Fishery Biology and Management. Fishing with ElectriCity. LondoD. Flshmg News (Boo ).
<br />
<br />Some Aspects of the Seasonal Distribution of Shelf
<br />Fishes in the New Zealand Area
<br />
<br />c .
<br />
<br />V. P. Shuntov
<br />Pacific Research InstitUte for Sea Fisheries and Oceanography (TINRO). Vladivostok
<br />
<br />Consideration is given In the paper to the results of the resea.rch of TINRO on the ~ew
<br />Zealand shelf In 1964-1968. Differences in the flpecies co~pr~sm~ the fish fauna iD dif-
<br />ferent areas of the shallows are connected with the zonal dlstnbutlon of water masses aDd
<br />te.mperature and with other hydrologic factors. Most of the fish species spawn. duriD~ the
<br />summer. In this connection the concentrations of shelf fi~hes teDd to ~e as~oclated With
<br />coastal waters and especially iDlets. Thermophillic species spawn maInly m subtropical
<br />waters A considerably smaller Dumber of species SpaWD in the mixed waters of the sub-
<br />tropicai convergeDce. At the eDd of the summer and iD~the first half of the autumn OD .
<br />completion of spawning many of the abundant species move to feed in the more .productlve
<br />waters of South Island. ID the second half of the autumn and throughout the. entire wmter
<br />departure of fishes into warmer Dorthern waters Is to be Doted. They contmue to move
<br />into greater depths within the shallo",:s and on the upper part of the continental slope.
<br />
<br />In 1964-1968 the Pacific Research Institute
<br />for Sea Fisheries and Oceanography organized
<br />and carried out for expeditions in the waters
<br />washing New Zealand." AttentioD was concen-
<br />trated in the work program of each .expedition
<br />
<br />on investigation of the shelf and slope using
<br />otter trawls (31. 0 and 31. 7 m). At the same
<br />time studies were made of the enviroDmental
<br />cODditions of fishes (temperature, saliDity,
<br />biogeDous elements, currents, plankton).
<br />Approximately 1300 trawliDg operatioDS were
<br />carried out on the shelf and slope down to a
<br />depth of 1000 m duriDg the work of all three
<br />expeditioDs between the northern tip of New
<br />Zealand and the sub-Antarctic Campbell Island
<br />in the South.
<br />
<br />.. The author of this paper was ID charge
<br />. of three expeditioDs on the vessels Akademik
<br />~, Seskar and Lira.
<br />
<br />372
<br />
<br />
<br />The investigations conformed the previously
<br />held opinion (Graham, 1953) that there are
<br />cODsiderable stocks of various fish species in
<br />the New Zealand area.
<br />
<br />The local marine fishing industry is poorly
<br />developed in New Zealand: the annual catch
<br />is DO more than 30 million kg of fish and in-
<br />vertebrates (Report on Fisheries for 1964,
<br />1965). In recent years, however, the Japanese,
<br />who began prospecting operations in this area
<br />long ago, have been developing fishing at a
<br />rapid rate.
<br />
<br />Composition of the Dominant Fish Species
<br />in Different Areas of the Shelf
<br />
<br />New Zealand lies in the path of two powerful
<br />currents: the warm Tasman Current (a con-
<br />tinuation of the East Australian CurreDt) and the
<br />cold West Wind Drift. These curreDts carry
<br />waters of two different structures: subtropical
<br />and sub-Antarctic. The boundary between
<br />them, the subtropical convergence, coincides
<br />with the 14.5'C surface isotherm in the sum-
<br />mer and with the 11.5'C surface isotherm in
<br />the Winter (Deacon, 1937) and with the 34.8 %.
<br />isohaline (Garner, 1959). The convergence
<br />extends in the area of the Chatham Rise, but
<br />it turns southward along the eastern coast of
<br />South Island. The result is that the islands
<br />lying south of New Zealand (Auckland, Bounty,
<br />the Antipodes and Campbell) are washed by
<br />sub-Antarctic waters, the whole of North
<br />Island and the northern part of South Island are
<br />washed by subtropical waters, and a consider-
<br />able part of the South Island shelf is iD the zone
<br />in which the water masses mix (Burling, 1961;
<br />Garner, 1962).
<br />
<br />The unequal environmental conditions in the
<br />areas occupied by the different water masses
<br />make the subtropical convergence an important
<br />biogeographical boundary.
<br />
<br />In cOlUlection with the zonal distribution of
<br />water masses and also with the significant dif-
<br />ferences in water temperature, which varies
<br />between the northern tip of New Zealand and
<br />the southern tip from 20-22' to 13'C in the
<br />summer and from 15' to 8-10'C in the winter,
<br />gradual depletion of the number of species in
<br />the fauna is to be noted on moving from North
<br />to South. We do not as yet have data on the
<br />distribution of all New Zealand fish speci(;>;,
<br />but analysis of their distribution in terms of
<br />frequency of occurrence in trawl catches in
<br />the period of our expeditions shows that only
<br />approximately a quarter of the shelf species
<br />have their southern limit in the area of North
<br />Island and the northern tip of South Island. A
<br />conSiderably larger group of species pene-
<br />trates into the zone of water mixing, but only
<br />a few species reach the lower tip of South
<br />
<br />Island." Such common thermophillic fishes as
<br />the golden jack (Caranx lutescens), (Pa~osomus
<br />auratus), the yellowtail (Seriola fgrandiS , the
<br />"hedgehog" (AllomycteruS}iCiiIi erus), the John
<br />dory (Zeus faber) and others tend to be ass.oci-
<br />ated in their distribution with subtropical water
<br />masses, i. e., to inhabit the waters of North
<br />Island and the northern tip of South Island. They
<br />do DOt extend or extend only iD the summer in
<br />very limited quantity southward into the zone of
<br />convergence.
<br />
<br />North of the zone of convergence lie the main
<br />conceDtration areas of the New Zealand jack
<br />(Trachurus declivis), the Australian salmon
<br />(Arripis trutta), (Chelidonichthys kumu) and
<br />(Anchenocerus punctatus). However, they are
<br />also comparatively common in the zone of
<br />water mixing.
<br />
<br />Subtropical waters and the mixing zone are
<br />inhabited by species in commerical abundance:
<br />the snoek (Thyrsites atun) , the sprat (Starffus
<br />antiradUm), the "red cod" (Physiculusbachus),
<br />the apuka (Polyprion oxygeneios), the riifflsh
<br />(Callorynhus milli), the spiny dogfish (Squalus
<br />kirki) and others. These species, with the
<br />exception of the spiny dogfish, are quite often
<br />also found off North Island, but the bulk of them
<br />are in the waters of South Island.
<br />
<br />Characteristic examples of the distribution
<br />ranges of species of each of the groups cited
<br />are given in Figs. 1 and 2.
<br />
<br />Finally, in addition to the foregOing species,
<br />whose concentrations are associated either with
<br />subtropical waters or with the mixed waters of
<br />the convergenoe, we must also mention the
<br />jackass fish (Nemadactylus maeropterus), the
<br />rock perch (Helicolenus papilosus), the sardine
<br />(Sardinops neoPITCiiiiTIliis), the anchovy (Engrau-
<br />lis australis), Seriolella brama and some others
<br />which are plentiful in subtropical waters and in
<br />the zone of convergence. In addition to the
<br />species already mentioned we should add to the
<br />list of abundant species of the New Zealand shelf
<br />soles, sharks, Pacific mackerel, billfish,
<br />Hemerocoetes ~ and others.
<br />
<br />Features of the Distribution and Behavior of
<br />Fishes in the Summer
<br />
<br />The outline of currents in the New Zealand
<br />area described above on the basis of the papers
<br />of Garner (1962) and Burling (1961) is in general
<br />characteristic of all seasons. Burling notes
<br />
<br />* The sardine has been recorded even in
<br />the subtropical waters around the Auckland
<br />Islands (Blackburn, 1960). However, such
<br />instances do Dot distort the general picture.
<br />
<br />373
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