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. . -;. .. '.; ... . THIS PAPER NOT TO BE CITED WlTHOUT/PRIORREFERENCE TO THEAUTHORS :-1.. > • International' Councii for the ICES CM:i9Bl/K:12 Exploration of the sea Shcllfish Commlttee THE INCIDENCE OF THE DISEASE GAFFKAEMrA IN NATIVE () AND IMPORTED LOaSTERS (Homarus americanus) IN ENGLAND AND WALES E. Edwards;. P~ A. Ayres and Mary L. Cullum Mlnistry of Agrlculture, Fisheries and Food, Directorate of Fisheries Research, F!sheries Laboratory, Burnham-on-Crouch, Essex CMO BHA; England

ABSTRACT '" Outbreaks'of are rare in the U.K. flsherles; the few outbreakS which have 'been reported during the past 25 years being usualiy associated W!th the !mport"of' from other countries within • America~ Europe or from No Sampllng during the years 1979-19Bl has lndicated that asigriificant proportion'of' th~ imported H. amer!canus were irifected, .but no cases of Gaffkaerilia; were recorded in lob~ters' 'caught

around . England and Wales 0 "

RESUME-- -- Les ~ruptlons de la maladle Gaffkaemia sont rares dans les pacheries de homard due Royaume Uni: celles qUi ont ~t~ observ~es pendant les vingt cing derni~res ann~es provenaient de homards'lmport~s diautres pays d'Europe ou de l'Amerique du nord. Les pr~l~vements des'~nn~es 1979-1981 ont montr~ qu'une proportion importante de' H. americanus import~e ~tait 4It coritamin~e, mais cette maladie nia'jamais~t~'observ~e sur les homards captur~s autour de l'Arigleterre et du Pays de Galles.

INTRODUCTION Gaffkaemia is a bacterial disease of lobsters of the genus Homarus, which under'certain conditions may cause high mortality.lbe bacterium which causes the disease - vlridans - is found naturally and may cause mortality to lobsters in thc' wild. However, it is particularly infectious in storage units; where lobsters' are often held at high density and sometimes underunfavourable conditions.

1 Gaffkaemia is very common in N. America where the disease is amajor " ., .: : ..~ ) fJ, :-. -: J ~; C 't ') ~ , •••' 6 ~.~.~ ~"-1 ~'. i-; .. problem to lobster merchants. In Canada, high levels of the disease have

" "....,: • --<1 .•-~ ,.,1 : becn associated with the COInmon practice of storing H.' amer!canus for 'long .. ... ~ I. ~ ~ periods in coastal storage tanks. prior to 'shipment abroad (Stew;rt,'" 1980). " . I • '. {., ':': .:. ~.1;·!,:· To date the incidence of Gaffkaemia in the U.K. is low. The few smaH outbreaks (Ayres et al.~ in preparation), have~su'ally beert ,,:" ;::,

'. /'. " .' ~ •• . ':: ~. . '. '•• " ~ 1 ~" associated with the introduction of imported lobsters to holding units' in the country,. although a few European lobsters have been 'sh~wn to' 'ca~r'y, . '. A. viridans.; 'In recent years the good supply and competitive price of the American '. • I" . ' 10bste~··fr·Oin the eastern seaboards of Canada and the United States has encouraged their export to the U.K. and other European countries. U.K. importers ?ave.suffered various levels o~ mortality with imported H. americanus and tests have indicated the presence of Gaffkaem.1.a. :... , In, view of this potential hazardto the U.K. lobster. fishery - worth ~5 • over million per annum·- a programme was set up in 1979 to evaluate the . '.. levelof the disease in imported Canadian lobsters. At.the same time, . .. ~ .'" . tests were made onlocally-caugh~. lobsters held in.storage,units all round England and Wales. The sampling programme is being continued but the' preliminary results are presented here, together with some background to the microbiological tests for this disease. :.

. . . RESULTS .ln 1973, an .leES report was produced by this laboratory (Ayres.~ a1. , 1973) :as part of an agreed survey of. European lobster stocks to determine .the incidence of Gaffkaemia•.. lt was concluded .that .of the lobs­ ters examined i~ 1973 ~rom waters around England and Wales, 0.66% were carriers of A. viridans. • Since that time, mortalities of lobsters in lobster storage tanks in England and Wales have been monitored. Microscopic smear examinations of post mortem sampies of 11. gammarus s~nt,in by commerical ·lobster merchants were performed throughout the period 1973 to 1978 and no evidence of :' Gaffkaemia was found. However,. in September 1978 large losses occurred in . a s~orage pond in Wales; the problem was not reported'until most of the stock had been lo~t:or disposed.of·but· it·was. understood,that mortalities commenced with H. gammarus introduced from astorage pond in Ireland'- All post mortem sampIes revealed severe Gaffkaemia infection on microscopic examination. Later in the same year unusually high mortalities, also

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amongst H. gammarus,' occurred' in'a' storage pond in southern Englä~d~" Th~' merchant noted,:thatlösses',first appeared' in 'lobsteFs transferred fr~m' a " storage. pond in :Scotland. :', ExaminaÜon of 'post martern samples' confi~m:e:d' thatit wasthe Scottish 'lobsters which had' Gaffkaemia while'.'locaf;' ~ : c-" freshly caught ::stock,. had not." There was no conclusive evide~ce" to' 'stipporl the claim that .imported"lobsters, had ,not beeri held befote the 'lösses ':: .. :, occurred. Thus; although there is eviderice that natural stocks of

• I : ~ ," ~. .... ',. ~ : European lobsters around England and Wales may carry strains of A. viridans,"froin observation~ made for'at least 8 ycars, there'is tid ev:l­ dence that· the, 'level. of infectiön' is sufficient to 'cause deaths 'of iobs-':;

, . . • _,._ ~ .~,';. ) . .- t , ..... '. • ters held in storage uriits. Wherever Gaffkaemia' has occurred,. it has" , . .. . '. ~. • .' t ... \ ~ '. always been in ·imported. stocks or in European lobsters where there" i8' .. positive: or' circumstantial: evidence that they have been stored' in elose"';' • proxim1ty:,to .:imported 'stocks~ ','_: '.... ',: ..

In, 1979, one' of~, the maj or' Canadian· exporters . cf' H. american"Us to' the": I U.K. and Europe leased a large holding facility in.England' cind we '~~re;' "",; consulted.about:mortalities.wh1ch occu;~ed there. OUt of'the fir~t b~tch •..• _.•... ~ ..... _.0 .,' " ,.~ :~." ..', " ~ .' . .. . of 11, animals,examined; 6 were' found to have Gaffkaemia on' direct mlcro-

, " c. • • ,'-t ."' l, ," . ."'_: ': " .. :. " scopic examination and the remaining5 yielded presumptive strains of A. viridans 'on cuÜure~ 'Importers of· N. American 'lobsters from :tw other sources. in N.·America have.been· located but'the numbe~s of' lobsi::ers from . these sources are comparatively smal!. At the time'of ',wdting, 512 H. americanus .,from· these sources , have been examined since October 1979 (Table 1) •. : Eighty-five of these' (16 ~ 6%), most of which were' dead .. or dying, .·were diagnosed as having Gaffkaemia on the'evidenc~ of blood smears and a further 52 (10.2%) yielded cultures identified as A: viridarts according to thescheme: of Stewart (1972). The inajority 'of this latter group of· animals were alive and apparently healthywhen'examined although up . to 50%, of similar batches held in the laboratory'for a' periocl 'o'f two to three~ weeks at: 10-15°C 'havc ~ 'siJbsequently died 6:om Gaffkaemia~'· ; Add:ltion­ aliy, eultures of. A.'viridans from these lobsters were ShOwrl tö'be pathogenic to other lobsters;, In an effort to-try.to obtain awider estimate ~f the potential;" problem; similar sampiing'was'performed on'H. 'gammarus' from other'storage plants. Results of this sampling are shown in Table 2. It'was iritended that only freshly caught lobsters were to be sampled but in practiee most sampling was performed at storage sites and the origins of the animals may not have been where they were sampled. It is likely that same lobsters had been stored for varying periods and even elsewhere at other sites thus 3 " increasing ,the possibility that Gaffkaemia ,could :be identified;,A tota1~, • ',; ~ f ..:" ~.; • ..'• " • - • • • of 484 lobsters was sampled and 4 yielded cu1tures provisionally' 'J'.' f, " '. ~ • " .• identified ,as A. viridans •. No direct microscopic examinations, even of'·" dead animals showed any evldence of Gaffkaemia, suggesting that the1evel'; of infection is too 10w for the organism to be pathogenic; or that .' .' ,". ~ :: '. naturallY-.occur:,ring strains of. A. viridans are non-virulent•..

... .- , ,." ',- ~ ~ .'. . . .~ . DISCUSSION In a consideration of the resu1ts obtained it shou1d be emph~siz~d' : that, much of the, sampling. was incidenta1,. to coastal visits for other '/' .. " .' , , purposes, (i.e. lobster conservation programme). Additiona11y, many of the ~ , "-" animals. s~mpled, particu1ar1y H. americanus, were dead' or dying and so" a1though simi1ar numbers of each species have been examined they were not strict1y comparab1e in other respects. However, a number of points have' ~ eme~ged.~oth ;rom the Gaffkaemia studies and from information gathered within the lobster trade. " 1. The natural incidence of.A. viridans in native~Homarus gammarus ,', : stocks around England and Wales .appears to be verylow, and the organism.appears to be of 10w viru1ence. 2. O':!tbrE7aks of ,Gaffkaemia. in tank systems in theU.K. have been; associated with the introduction.of H. americanus, from;Canada . " \.. ~ and H. gammarus fromIreland and Scot1and. 3. S,amp1ing o~ live and dead stored lobsters revea1s that,there i8 a re1at~ye1y: high incidence of Gaffkaemia in imported .!!:.. ' americanus, though. this varies both seasona11y and inconsign~' ments. 4. Where outbreaks of Gaffkaemia have occurred they have been a~d • sporadic a1ways associatedwith lobsters which have been stored for considerable periods, oftenat more than one site and under poor conditions (high density, high ,temperature) •. Subse- .! :; • quent1y, stock stored for only a few days in the presence of infected lobsters has also become infected and died. 5. All infected H. americanus either showed damage to the integu­ .~ent"inc1uding 10ss of 1imbs and/or had c1aws immobilized with wooden pegs.

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'":' .~.~' . .', ~ 4 • 6. Freshly isolated strains.of ·from heavily infected lobsters have been shown to be pathogenic ~hen injected into healthy animals(both H. americanus and H. gammarus), in contrast to strains from natural stocks of H. gammarus which appear to. be of negligible pathogenicity. In conclusion, we have demonstrated that although there may be a low natural incidence of A. viridans in the natural stocks of the lobster H. gammarus, this has not caused outbreaks of Gaffkaemiaduring storage. On the other hand, infection and problems of mortality due to Gaffkaemia are significantly higher in imported H. americanus. We are therefore concerned that unrestricted introduction and storage of these imported lobsters may infect stored H. gammarus, causing mortality.

REFERENCES AYRES, P. A., HALLS, S. and EDWARDS, E., (1973) Incidence of Gaffkya homari in natural lobster stocks - preliminary results of a survey of the English and Welsh fisheri~s. ICES CM 1973/~:20,. 3 pp (mimeo). STEWART, J. E., (1972) The dete~tion.of Gaffkya homari, the bacterium ". pathogenic .to.lobsters (genus Homarus). Circ. Fish. Res. Bel Can., N.S. (Halifax Laboratory) (43) 5 pp~ STEWART, J. E., (1980) Diseases. pp. 301-342 In: The Biology and Management of Lobsters. I. Physiology and Behaviour (Eds. COBB, J.S. and PHILLIPS, B. F.). Academic Press, New York & London~

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l .. r '. Table 1 Sampling of Homarus americanus 1979-1981 and incidence of Gaffkaemia ,.

No examined No presumptive No positive Negative positive in direct blood broth culture smear

Source A 435 52 71 312 B 76 o 13 63 c 1 o 1 o

Totals 512 52 85 375

% 10.2 16.6 73.2

Table 2 'Sampling of Homarus gammarus 1979-1981 and incidence of • Gaffkaemia

Origin . No 'examined No presumptive No positive Negative positive in direct blood . broth culture smear

S. Wales 137 0 0' 137" . N. Wales 16 0 ,0 16 N.E. England .137 0 0 137 S. England 146 4 0 142 S.E. England 48 0 0 48

Totals 484 4 0 480

% 0!8 0 99.2 •