Cancerous Pike in Ireland

Cancerous Pike in IrelandAuthor(s): Maire F. Mulcahy and Fergus J. O'RourkeSource: The Irish Naturalists' Journal, Vol. 14, No. 12 (Oct., 1964), pp. 312-315Published by: Irish Naturalists' Journal Ltd.Stable URL: http://www.jstor.org/stable/25536906 .

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312

CANCEROUS PIKE IN IRELAND

By Maire F. Mulcahy and Fergus J. O'Rourke

During the past ten years an intensive pike eradication scheme has been in progress in Irish lakes and rivers under the auspices of the Inland Fisheries

Trust. Among the thousands of pike removed a number with noticeable tumours have been detected.

lJ\ /"c^^/rr^^n^T^Tn^t S^ ^^a^rs wkem cancerous Cm***A*~>

iyfj(iff/ f/jI i

fj^^ mi

pike, have been taken

y^^y_rm^^^^ 0.Anro5 of pike

eradication.

%$ Areas of pike eradication whore no

neoplastic pike, have been found.



313

In an effort to determine the incidence and distribution of cancerous pike in the Republic of Ireland, a questionnaire was sent out to the Area Superintendents of the Inland Fisheries Trust, in the main areas in which pike work is in progress. The pike eradication areas are located mainly in the south and west of the country, and the waters concerned are shown in the map. The information obtained from the questionnaire is summarized in the Table.

TABLE I

Approximate figures for cancerous pike in Ireland.

Minimum Cancerous Pike Total No. Cancerous Incidence

Area from of Pike Pike per thousand

CORK Lee river and 47,000 >100 2.10 reservoirs*

S. CO. MAYO L Mask 48,000 35-40 0.73 L. Cloon

L. Carra

L. Nafoey

R. Robe

R. Derrymore

N. CO. MAYO L. Conn 20,000 It 0.05

MID. CO. MAYO ? 6,000 ? ?

N. CO. GALWAY L. Corrib 27,000 >5 0.18

S. CO. GALWAY L. Corrib 9,000 2 0.22

E. CO. GALWAY R. Shiven 11,700 25-30 2.14 R. Bunowen

R. Suck

R. Castlegar R. Killeglan

W. CO. CLARE ?

6,000 ? ?

CO. ROSCOMMON L. Arrow 10,500 25-35 2.38 L. Gara

L. Cullentra

R. Arrow

R. Lung

CO. CAVAN L. Sheelin 50,000 130 2.60 R. Derrylea

N. WE3TMEATH L. Sheelin 60,000 >16 0.27 R. Inny

S. WESTMEATH L. Owel ? 20-30 ? L. Ennell

MIDLAND Little Brosna R. 30,000 35-45 1.17

*In both 1955 and 1958, two cancerous pike were taken from R. Sullane; and in 1958 one was taken from Blarney Lake.

tThis fish (C 10) will be fully described in a forthcoming paper,



314

The appearance, distribution in the body and histology of the lesions have been described in detail by Mulcahy (1963). The general appearance of an infected pike is shown in the figures.

Fig. 1?C 1: Growth from right side of lower jaw.

Fig. 2?C 2: Floor of Mouth.

Fig. 3?Roof of mouth of C 2 showing triple growth coalescing at anterior end.

Fig. 4?-C 3 showing areas of inflammation (within dotted lines), and growths.

It can be seen from the map that neoplastic growths in pike are found in most, but not all areas where eradication is being carried out. There is a wide variation in the incidence of the diseased pike, very many occurring in some areas, and few or none in others.

In all cases the number of cancerous pike is approximate as unfor tunately no systematic records of them were kept, and the replies to our

questionnaire were to a large extent from memory. The figures quoted are also subject to error; for instance in some cases injury marks may have been mistaken for tumours; furthermore pike having only small external tumours would in many cases not be recognised as diseased. The fish were only superficially examined so that pike having internal tumours only, would have been classed as non cancerous.

Where tumours were particularly looked for by observers the number that occurred was remarkably high. Thus of 120 pike which were caught in a pike fishing competition on the River Lee, County Cork, two had external tumours (16.6 per thousand). In Cavan, so many growths were noticed on the pike

during 1958 that two catches of pike were examined in more detail by Inland Fishery Trust workers. In one catch of 300 pike, one in eight had tumours (125 per thousand); and in a second lot of 999 pike, one fish in twelve was cancerous (83.3 per thousand). This indicates that the approximate incidence quoted in the Table for the various areas is probably far below the true figure.



315

In the areas where cancerous pike have been found the incidence varied from 0.05 per thousand in North Oounty Mayo, to 2.60 per thousand in County

Cavan, which County had the 12.5% incidence in 300 fish closely examined. The cancerous pike varied in weight from quarter of a pound to thirty

pounds with an average of five to seven pounds. The tumours were found either in the mouth or on the trunk or both; although in South Co. Galway trunk

growths only were noticed, and in Cavan the growths were found mainly in the mouth. Growths projecting from the nostrils have been found in one fish from the Sullane River and in two from the River Lee in County Cork. The condition of the cancerous pike varied greatly, some pike seemed unaffected by the presence of the tumours, whereas others, often with fewer tumours, were thin and in poor condition.

Inland Fisheries Trust workers found as a rule that the number of pike with tumours taken at the start of eradication operations in an area, was greater than during subsequent years, and that there was a gradual fall off in the incidence. On the other hand, 1953 was especially mentioned in two areas, Co. Cavan and South^Co. Mayo, as the year in which the greatest number of diseased

pike had been taken, although in each case clearing operations had been in progress for a number of years.

There is no major geological or geochemical difference between the areas in which cancerous pike have been taken and those in which they have not. No geological feature, common to all the other pike eradication areas, is absent from

West County Clare, and Central County Mayo. It is possible that detailed water analysis in the latter areas might reveal the presence or absence* of some trace element, not shown by the other areas, which might be associated with the

presence or absence of the neoplasms.

The areas in which no cancerous pike have been found are among those in which the smallest numbers of pike are removed during eradication each year.

This suggests the possibility that the occurrence of the neoplasms may be associated with high population densities of the pike.

We are very grateful to the many members of the staff of the Inland Fisheries Trust who have supplied us with specimens and information.

We would much appreciate further information on the distribution and incidence of this disease in pike.

Department of Zoology, University College, Cork.

REFERENCE

Mulcahy, M. F. (1963). Lymposarcoma in the Pike, Esox lucius LM (Pisces; Esocidae) in Ireland, Proc. Roy. Irish Acad. LXIII (B 7) 103-129.

ISCHNOPSYLLUS INTERMEDIUS (ROTHSCHILD), A BAT FLEA NEW TO CO. CORK

By Fergus J. O'Rourke

C. B. Moffat (1938) lists the Hairy-armed or Leister's bat, Nyctalus leisleri (Kuhl), as the third commonest of the seven species of bats found in Ireland.

He recorded it from 17 counties including Cork where the locality listed was Fermoy, H5, (EC). Leister's bat frequently enters my house at Rushbrooke OBC) and a number of specimens have been collected and kept in the laboratory. Fleas from these bats have been removed and examined and all have so far proved to toe females of the species Ischnopsyllus (Ischnopsyllus intermedius (Rothschild)) a flea hitherto recorded in Ireland only from Counties Down and Tyrone (Carlisle and Skillen 1960). Of the six (bats examined here there were fleas on

three which were collected on December 15th, 1961 (one flea), December 8th, 1963 (four specimens) and December 12th, 1963 (two (specimens).

In Britain /. intermedius has been found not only on Leister's bat but

also on the Serotine bat, Eptesicus serotinus (Schreber), and on the Noctule,



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Cancerous Pike in Ireland