JELLYFISH, JELLYPRESS AND JELLYPERCEPTION

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1 JELLYFISH, JELLYPRESS AND JELLYPERCEPTION ILVO MEDEDELING nr 142 nvember 2013 S. Vandendriessche L. Vansteenbrugge K. Hstens H. Maelfait (1) (1) PAK (Prvinciaal Ankerpunt Kust)

2 Jellyfish, jellypress and jellyperceptin ILVO MEDEDELING nr 142 nvember 2013 ISSN Wettelijk Dept: D/2013/10.970/142 S. Vandendriessche L. Vansteenbrugge K. Hstens H. Maelfait (1) (1) PAK (Prvinciaal Ankerpunt Kust)

3 JELLYFISH, JELLYPRESS AND JELLYPERCEPTION Prject MEMO, activity 3 Final reprt Belgian case study Study cnducted within the framewrk f the Interreg IVa 2 Seas prject MEMO ( Mnemipsis eclgy and mdeling: Observatin f an invasive cmb jelly in the Nrth Sea )

4 Authrs: Sfie Vandendriessche, Lies Vansteenbrugge, Kris Hstens, and Hannelre Maelfait Cver: cpyright Merh Kiekebe album De Medusa Stichting T be cited as: Vandendriessche S., Vansteenbrugge L., Hstens K., Maelfait H. (2013) Jellyfish, jellypress and jellyperceptin. ILVO mededeling nr 142, ISSN , 21pp. 2

5 Cntents Abstract... 4 Intrductin... 5 Material and Methds... 6 Study area... 6 Media search... 6 Questinnaire survey... 6 Results... 7 Jellypress... 7 Jellyperceptin Discussin Jellyperceptin in the turism industry: cmparisn with ther studies Fisheries: interpretatin f anecdtes Jellypress versus jellyperceptin Relevance t integrated castal zne management and research Mnemipsis leidyi? References Annexes

6 Abstract During the last decades, the number f reprts n invasins and blms f jellyfish has increased, bth in scientific literature as in the general media. There is hwever n clarity abut a glbal rise f gelatinus zplanktn due t the lack f extended time series, and due t the fact that public perceptin is ptentially driven by the media. Hwever, public perceptin is a key driver in plicy decisins, including castal zne gvernance and research funding. Cnsequently, it is useful t investigate the variability within public perceptin and the relatinship between media and public perceptin in the light f plicy. This was investigated within a case study at the Belgian cast regarding the perceptin n jellyfish and the cnsequences f jellyfish blms, based n the results f a questinnaire survey and a media search. The results indicate that perceptin is nly partly driven by the press if it cmes t jellyfish. Persnal experience seems t be at least equally imprtant as driver. Additinally, the results indicate that there is a large variatin in perceptin n jellyfish, in this study illustrated by the differences in perceptin between beach turists and divers. The lack f knwledge abut differences between jellyfish species turns ut t be a key issue determining perceptin. Bth the variability in perceptin and the species issue are imprtant fr the incrpratin f the jellificatin prblem in integrated castal zne management. In first instance, it is imprtant t extend perceptin surveys t all grups directly and indirectly affected by jellyfish. By ding s, pprtunities may emerge fr cperatin between scientists, plicymakers and public parties in the frm f citizen science. Secndly, management actins cncerning jellyfish increases shuld include the prvisin f species-specific infrmatin, fr example by distributing leaflets and putting up warning bards n the beach. This wuld likely result in a higher acceptance f jellyfish, a better cmmunicatin between scientists and the public, and in a better quality f data in citizen science prgrams. 4

7 Intrductin During the last decades, the number f reprts n invasins and blms f jellyfish has increased, bth in scientific literature as in the general media (Cndn et al, 2012). Such invasins and blms can have a substantial impact n human activities, including the clgging f fishing nets and cling water intakes in pwer plants, an increase in stings amng turists, ecnmic lsses in the turism industry, and damage t aquaculture systems (Purcell et al, 2007; Ber, 2013). Given these smetimes dramatic cnsequences, the number f reprts has increased and the public, thrugh the media, became aware f the cean jellificatin prcess which is presumably driven by human impacts such as eutrphicatin, climate change, verfishing, hard substrate additin, aquaculture and transprt f nn-indigenus species (Richardsn et al, 2009; Purcell et al, 2007; Purcell, 2012). Hwever, histric data n jellyfish blms are very scarce, and althugh there is evidence f lcal and/r glbal jellificatin (Brdeur et al, 1999; Licandr et al, 2010; Brtz et al, 2012), Cndn et al (2012) have questined a glbal rise f gelatinus zplanktn based n the lack f extended time series, and n the fact that public perceptin is ptentially driven by the media. Studies n public perceptin regarding jellyfish have recently been carried ut in Germany (Baumann, 2009; Baumann & Schernewski, 2012), in Malta (Ciantar, 2012), in France (Bnnet, 2013) and in Califrnia (Kaneshiri-Pinheir, 2013), and were based n data f jellyfish abundances and results f surveys. The evlutin f the number f jellyfish articles in the general media was analyzed by Cndn et al (2012), in which the number f Ggle News articles was cmpared with the number f scientific papers in Web f Science in the perid In Germany, Baumann (2009) reprted n a similar analysis frm fur newspapers ver the last 30 years. Bth authrs fund an increase in the media reprts n jellyfish. The influence f the general media n public perceptin cncerning jellyfish, was hwever nt addressed in any f these studies. Hwever, public perceptin is a key driver in plicy decisins, including castal zne gvernance and research funding. Cnsequently, it is useful t investigate the variability within public perceptin and the relatinship between media and public perceptin in the light f plicy. This was investigated within a case study at the Belgian cast regarding the perceptin n jellyfish and the cnsequences f jellyfish blms. The study was triggered by the ccurrence f the nn-indigenus ctenphre Mnemipsis leidyi in Belgian waters (Van Ginderdeuren et al, 2012), and the subsequent threats t cmmercial activities such as fisheries and turism. The current study was designed t answer the fllwing research questins: 1/ What is the perceptin f peple frm the turism and fisheries industries n jellyfish and n the sci-ecnmic threats assciated with jellyfish blms? 2/ What are the main messages spread by the general media abut jellyfish and d these messages agree with the public knwledge and perceptin? The answers t these questins were discussed in the framewrk f integrated castal zne management. 5

8 Material and Methds Study area The study was carried ut at the Belgian cast. The Belgian part f the Nrth Sea (BPNS) is situated in the suthern bight f the Nrth Sea and is characterized by an intense explitatin f its natural resurces (e.g. fisheries, sand extractin, renewable energy) and a high level f disturbance (e.g. dredging, beam trawl activity, shipping, turism) (Maes et al, 2005). As such, it can be categrized as a regin with high human impact, where jellyfish culd prliferate and cause prblems (Purcell, 2012). Jellyfish blms f Chrysara hysscella, Aurelia aurita r Cyanea lamarckii have been reprted repeatedly in the general media, but the recent scientific interest in jellyfish was triggered by the bservatin f the nn-indigenus and ptentially invasive ctenphre Mnemipsis leidyi in Belgian waters (Van Ginderdeuren et al, 2012). The current analysis was carried ut as part f the internatinal prject MEMO, in which sci-ecnmic cnsequences f M. leidyi presence and abundance were investigated. Media search Using the digital press archive Mediargus ( all Flemish newspapers issued between January 1, 2000 and September 21, 2012 were searched fr articles featuring jellyfish. All results were entered in an Access database listing title, date, surce, species (if specified), regin (if specified), categry (health, science, cnsequences f blms, and drama) and key wrds (wrds that cnvey the cntent f the article, selected by the authr f this study). Every article was scanned fr mentins f causes and threats f, and slutins fr jellyfish blms. Fr the analysis, nly articles in which jellyfish were the key news item were retained. Mentins f jellyfish in travel reprts, in satiric clumns (in which jellyfish is mstly used as a reprach), advertising and sprts items were nt used. Questinnaire survey Fr the survey, three grups were targeted, i.e. the turism industry, pwer plants with cling water intakes and the fisheries industry. Fr each grup, a questinnaire was develped. Since nly few peple knw the differences between species, the survey was generalized t jellyfish, i.e. Scyphza, Hydrza and Ctenphra. The questinnaire fr the turism industry was adapted frm the ne develped within the GELAMED prject (Bnnet, 2013), while the pwer plant and fishermen surveys were develped within the MEMO prject (Schaafsma et al, 2013). In the turism industry questinnaire, the questins are all multiple-chice and clsed. They can be subdivided in (1) persnal infrmatin (gender, age, relatin t the cast), (2) persnal perceptin n jellyfish (experiences, emtins, bservatins) and (3) a persnal pinin n the imprtance f jellyfish increases and their cnsequences, n their causes and n plicy measures. The questinnaire features a general part fr all participants and specific parts nly filled ut by turists and recreants, prfessinals frm the turism industry r lcal fficials. These specific parts cnsider specificatins n turist activities (timing, type) and impact f jellyfish abundance n these activities, specificatins n prfessinal activities and perceived threats fr these activities, and perceived threats and pssible plicy measures, respectively. The fisheries and pwer plant surveys were less persnal, and cntained questins n bservatins f jellyfish, reactins f fishermen and industrials, and financial 6

9 # articles lsses. Stries, persnal experiences and remarks frm respndents were listed and used in the interpretatin f the results. The questinnaire survey was dne in summer Questinnaires were distributed bth physically (field survey at the beach and dike f Ostende) and digitally ( survey). At the time f the field survey, jellyfish (C. hysscella) were present in the water and n the beach. Their abundance was mderate, i.e. turists and recreants never saw mre than five individuals in the water r n the beach n the day f the survey. Results Jellypress In ttal, 140 articles were used in the analysis. Since 2000, the ttal number f articles has steadily increased twards a peak in 2010 (fig 1). Abut a quarter f the articles dealt with lcal jellyfish news n the Belgian part f the Nrth Sea (BPNS). Their number remained lw with a mderate peak in 2005 and increasing numbers since all lcal Figure 1. Evlutin f the number f articles featuring jellyfish in the Flemish general media since 2000 (all = general news; lcal = lcal news related t the Belgian Part f the Nrth Sea) In abut half f the articles, the jellyfish species was specified. The representatin f species differed substantially ver the years (fig. 2). The Nrth Sea jellyfish species were mentined mst and included Aurelia aurita, Chrysara hysscella, Cyanea lamarckii, Cyanea capillata and Rhizstma ctpus. Articles n Mnemipsis leidyi first appeared in 2000, reprting n its deleterius effects in the Caspian Sea. In 2010, the presence f this species in the Nrth Sea was first reprted in the press and kept getting press attentin in Reprts n ther species mstly riginated frm the Atlantic (UK and USA), the Mediterranean (especially Spain, which is a ppular hliday destinatin), and frm the Pacific (especially Australia and Japan)(fig. 3). 7

10 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% unspecified Turritpsis nutricla Tiburnia granrj Stmlphus nmurai Rhizstma ctpus Physalia physalis Carybdea marsupialis Pelagia nctiluca Mnemipsis leidyi Cyanea lamarckii Cyanea capillata Chrysara hysscella Chirnex fleckeri Carukia barnesi Aurelia aurita 0% Figure 2. Evlutin f featured jellyfish species in the Flemish general media since Percent f articles mentining specific regin/cuntries/bassins 0 general Belgium Nrth Sea Carribean UK US general Italy Jerusalem Sardinia Spain Japan Australia Thailand unspecified Atlantic Mediterranean Pacific Caspian Sea Indian cean Black Sea Figure 3. Gegraphic rigins f jellyfish news appearing in Flemish general media Mst articles reprt n the ccurrence and cnsequences f jellyfish blms (71% f all articles, 87% f the articles cncerning the BPNS). Scientific findings (e.g. Scientists make jellyfish frm a rat ) accunt fr 14%, and health related tpics (e.g. cures fr stings) fr 4% f all articles (10% and 3% f the BPNS articles, respectively). Reprts n dramatic encunters with jellyfish accunt fr 12% f all articles, while nt a single drama article was published abut the BPNS. The headlines f these articles are usually quite spectacular (e.g. Jellyfish kills wman in Sardinia ), and are predminantly abut encunters with Carukia barnesi and Chirnex fleckeri in Australia, r with Physalia physalis in suthern Eurpe. The tp 30 f key wrds reflects the general messages f the press releases. They mstly refer t (1) the causes and ecnmic cnsequences f jellyfish blms, and (2) the persnal risks invlved with (pisnus) jellyfish encunters. When nly cnsidering articles featuring M. leidyi, the key wrds are all abut the eclgical and ecnmic threats psed by this nn-indigenus species. 8

11 Table 1. Tp 30 f key wrds, subdivided in wrds referring t jellyfish blms and persnal risks. Bld red wrds represent the tp 2, bld black wrds represent the tp 10. jellyfish blms verfishing infestatin warmth glbal warming wind fisheries fd pllutin temperature catch climate change nets planktn study persnal risks washed ashre turist swim beach pisn children dead inncent lethal sea water summer small sting pain tentacles allergic In 47% f the articles, specific causes f jellyfish blms were mentined, the mst imprtant nes being natural causes such as weather, currents r ppulatin dynamics, the lack f natural predatrs due t verfishing, and glbal warming. Specific threats and impacts were mentined by 41% f the articles. Impacts n fisheries and aquaculture, and cnsequences fr turism were by far the mst imprtant (fig. 4b). Slutins were mentined in nly 14% f the articles, f which the remval f jellyfish (in sme cases fr cnsumptin), the installatin f beach fences and the (re)intrductin f predatrs such as turtles were the mst cmmn (fig. 4c). The relative imprtance f causes, threats and slutins were hwever nt mentined in any f the articles. A natural causes B cl water intake/pwer plant threats - impacts shipping/ ballastwater pllutin/ eutrphicatin verfishing/ lack f predatrs glbal warming/climate change impact n turism/clsed beach impact n fisheries, fish stcks & aquaculture % f causes mentined % f threats mentined C slutins - measures intrduce predatr stp verfishing fences ballast water treatment Figure 4. Relative imprtance f causes, impacts and slutins fr jellyfish blms, as derived frm articles in the Flemish general media. remval/cnsumptin % f slutins mentined 9

12 Jellyperceptin In ttal, 69 questinnaires were cmpleted fr the turism industry. Only three fishermen respnded, s these results will be presented as anecdtal infrmatin. There were n respnses f representatives frm pwer plants with cling water intakes (table 2). The gender and age distributin amng participants f the turism industry survey was balanced with 53% men and 47% wmen, and with 13% 18 t 29 year lds, 24 % 30 t 39 year lds, 25% 40 t 49 year lds, 19% 50 t 59 years lds and 19% ver 60. Mst respndents (65%) visited the Belgian cast year rund fr recreatinal purpses, and twenty percent f the respndents nly visited the cast during the summer mnths. Cmmercial activities carried ut by respndents, such as the explitatin f a surf club r a bar, cntinued year rund. Recreatinal activities carried ut by the respndents included running and walking (64% f respndents), swimming (32%), diving (41%), sunbathing (18%), sailing, surfing, shpping, eating, fishing, sleeping etc. Since the respnses by divers (32) were abundant cmpared t the ther respnses frm the turism industry (37), these grups were treated separately in the analyses. Table 2. Number f respnses and used medium per survey grup Grup # respnses Medium turists - recreants 25 field survey divers 32 turism prfessinals 5 field survey lcal fficials 7 fishermen 3 pwer plants representatives 0 Turism industry When asking respndents abut 5 wrds they assciate with jellyfish, the results are quite different fr divers and ther recreatinists (fig. 5): divers fcus n anatmic characteristics (including beauty), distinguish between species and mentin the need fr cautin, while ther recreatinists d nt distinguish between species and are almst cmpletely fcused n negative aspects such as stings, the smell, the feeling when yu step n a jellyfish, etc. Key wrds related t ecnmic and eclgical cnsequences f blms were virtually absent frm the list. 10

13 nettle cells beautiful tentacles slimy transparant elegant pain sting cautin diversity nuisance gelatinus sea ful abundant beach Prtugese man ' war underwater dangerus clurs key wrds divers sting ful slime nuisance danger sea tentacles pain transparant fear beautiful cautin beach different species jelly slippery itch elegant pisnus smell key wrds ther respndents Figure 5. Key wrds assciated with jellyfish, as derived frm surveys by divers (left) and frm ther respndents frm the turism industry (right) All divers and 86% f the ther respndents had seen jellyfish during the last five years, but the latter admitted they had paid little attentin t jellyfish presence. Seventeen percent f the respnding divers had the impressin that the number f jellyfish had increased, while this was nly 5% fr the ther respndents frm the turism industry. One beach turist remarked that he might have the wrng impressin since Flemish beaches are cleaned very ften. When persns wh perceived an increase were asked whether the number had increased with factr 2, 5, 10 r 100, mst admitted they had n idea r nuanced the questin based n interspecific r seasnal differences. An bserved increase f M. leidyi, fr example, was specifically mentined by tw divers. Respndents were asked a number f questins t establish their frame f mind during a (hypthetical) encunter with a number f jellyfish. Mst peple said they stay calm and certain, sme get nervus and tense r dwnright scared but cautin is the dminant emtin (fig. 6). During several interviews, it was stated that n risks are taken when children are invlved, especially since mst f the turists cannt tell the difference between stinging and harmless species. That is nt the case with divers, wh usually have a gd knwledge f species and are mre at ease during a jellyfish encunter. Glbal change and verfishing were indicated mst ften as causes f the cean jellificatin prcess (35 and 29% f the respndents, respectively)(fig. 7). Ballast water transprt and life cycle characteristics f jellyfish were each mentined by 15% f the respndents. During the field survey, mst peple expressed the understanding that all prcesses are linked and that multiple interacting factrs are at the base f lcal and/r glbal jellyfish increases. Sixty-five percent f all respndents felt that they d nt knw enugh abut the recent develpments in jellyfish and wuld like t receive mre infrmatin abut the matter (fig. 7). 11

14 glbal change cean acidificatin verfishing rareness f turtles pllutin ballast water transprt life cycle characteristics f jellyfish wants t be infrmed des nt want t be infrmed % f respndents calm certain at ease relaxed tense cautius scared nervus calm certain at ease relaxed tense cautius scared nervus jellyfish and state f mind 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% n mre r less yes divers ther turists Figure 6. Variatins in the frame f mind f divers and ther peple frm the turism industry during a (hypthetical) jellyfish encunter 70 Accrding t yu, what are the causes f cean jellyficatin? Wuld yu like t receive mre infrmatin? Figure 7. Perceived causes f jellificatin (blue) and the desire t receive mre infrmatin n the matter (green) by respndents frm the turism industry (including divers) 12

15 As fr persnal invlvement, mst peple felt that lcal and/r glbal jellyfish increases d cncern them but they als mentined that there is little they can persnally d abut it (fig. 8). Hwever, ptential increases f jellyfish are cnsidered as a majr issue. One respndent made the cmparisn with txic algal blms. Mst respndents indicated that the recent develpments are the result f a glbal prcess and that the prblem shuld be dealt with as such. it desn't cncern me it is my prblem it is a small prblem I can make a difference it is a glbal prblem it is an imprtant issue Figure 8. Clr chart representing persnal invlvement f respndents based n three statements, in a scale f 1 t 5 (light green t dark green) A multiple chice questin was used t find ut what industry the public perceives t becme mst affected by an increased prevalence f jellyfish. Mst respndents (58%) checked fishermen and aquaculture farmers, 34% checked turists and recreants, 18% checked the turism industry (restaurants, camp site wners, etc.), and 9% checked lcal inhabitants. Nne f the respndents checked the lcal gvernments. perceived sectrs affected lcal gvernments fisheries & aquaculture turist sectr turists & recreants inhabitants Figure 9. Sectrs mst affected by an increased prevalence f jellyfish, as derived frm survey results (turism industry) Tw respndents remarked that turists will nly limitedly be affected because they will simply g elsewhere. This was nt cnfirmed by the survey results: nly 27% f the turists and recreants (including divers) said they wuld chse anther destinatin if jellyfish shuld be abundant (> 10 jellyfish visible n the beach r in the water). Seventeen percent stated that they wuld, hwever, change their activity (e.g. give up swimming). If the jellyfish wuld appear t be harmless and peple wuld be infrmed abut it, then half f this seventeen percent wuld change their mind. Fr thers, nly seeing jellyfish is enugh t change their activity. The risk f jellyfish stings is the mst imprtant factr fr turists and recreants, including divers, t make this decisin. Mst respndents think that increasing jellyfish densities will result in a substantial increase f stings. The risk f a beach clsure by lcal gvernments and life guards is estimated t be lwer, althugh lcal fficials indicated beach clsures as prbable results f jellyfish blms. Respndents carrying ut cmmercial activities at the cast are mst cncerned abut an increase in jellyfish stings and a decrease in cmmercially imprtant fish, factrs that might negatively impact the returns frm 13

16 turism and fisheries and the reputatin f the castal regin. Answers f lcal fficials agree with these cncerns and add the pssibility f increasing preventin csts t the list f cncerns. All csts resulting frm jellyfish blms (jellyfish fences, clean-ups, damage, etc.) shuld be paid fr by sciety thrugh taxes, accrding t 89% f the respndents. A minrity thinks that the turism industry r the fisheries industry shuld carry the csts (6 and 13%, respectively). Mst respndents (52%) feel that a remedy fr jellyfish increases shuld aim at lng-term results and shuld deal with the underlying causes, such as verfishing and pllutin (fig. 10). Still, 29% f the respndents thinks it wuld be a gd idea t start fishing fr jellyfish and prcess them in fd, medicine and csmetics. Only 1% sees a slutin in fenced swim znes. As fr the initializatin f preventive and mitigating measures, initiatives shuld be taken n a natinal and glbal level accrding t lcal fficials. slutins - measures reduce pllutin fenced swim znes fish and cnsume jellyfish remedy verfishing Figure 10. Relative imprtance f pssible slutins, as derived frm the turism industry survey results Respnses by fishermen were very limited, but we believe the anecdtal infrmatin is still valuable given the perceived threats t the fisheries industry. One f the fishermen claimed that jellyfish are f n cncern fr him since the net he uses features large meshes in the tp panel, thrugh which jellyfish can easily escape. Anther fisherman reprted a Cyanea blm in the UK, mre precisely in the Liverpl Bay in May 1988, that resulted in a lt f jellyfish bycatch and a relcatin t ther fishing grunds, which in turn resulted in an additinal fuel cst. A castal fishermen reprted Rhizstma bycatch in September 2012 f an rder f magnitude that inhibited fishing. Nne f these fishermen were aware f ever having seen r caught the ctenphre M. leidyi. Discussin Jellyperceptin in the turism industry: cmparisn with ther studies The results f this study n public perceptin are based n a limited and gegraphically lcalized questinnaire survey. Althugh the number f respndents is small cmpared t the surveys carried ut in Germany (Baumann & Schernewski, 2012), Califrnia (Kaneshir Pinheir, 2013) and France (Bnnet, 2013), the main results are quite similar. In accrdance t the GELAMED survey (France) fr example, the image f jellyfish is rather negative and especially beach turists have little sympathy 14

17 fr the creatures. In the present study, it was clear that the perceptin f recreatinal divers is quite different and mre psitive in general. This indicates a substantial variatin in perceptin within the grup f recreants. Althugh recreants such as yachtsmen, recreatinal anglers, surfers and divers are vastly utnumbered by beach turists sensu strictu, we think it is wrthwhile t include them in surveys as this ne. Additinally, reginal differences (castal cities and regins) and scial differences (prfessinal status) such as the nes bserved in France (Bnnet, 2013) shuld be investigated in mre detail. Anther result that agrees with previus surveys is the request fr infrmatin abut jellyfish species, their eclgy and the prblems they can cause. Mst turists cannt tell the difference between jellyfish species (except fr divers) r between stinging and harmless types, and are thus cautius with all jellyfish. A number f turists wuld give up relcatin plans in case f high jellyfish abundances if they wuld be infrmed that the jellyfish were harmless. Additinally, the majrity f respndents feel that they knw t little abut recent jellyfish develpments t answer questins n causes, threats and slutins, and wuld like t receive mre infrmatin n the matter. Since Baumann and Schernewski (2012) prved that prviding infrmatin is effective t increase the beach users acceptance f jellyfish, beach management measures cping with jellyfish increases shuld therefre include different cmmunicatin tls fr a brad public and fr beach users such as warning flags, leaflets, infrmatin bards and frecasts. Fisheries: interpretatin f anecdtes A recent study in Slvenia by Nastav et al (2013) shwed that high jellyfish abundances can result in reduced fish catches, in deteriratin f the fish quality, and in increased csts due t increased fuel use, thereby reducing the incme f fishermen. The lw respnse rate f the survey distributed amng Belgian fishermen culd indicate that jellyfish are nt (yet) cnsidered a majr prblem in Belgian fisheries. Indeed, ne f the fishermen states that the mesh size f beam trawl nets allws jellyfish t escape. On the ther hand, increased fuel csts fllwing relcatin t jellyfish-free fishing grunds and clgging f nets were reprted. Additinally, Maes et al (2013) reprt n statements f Belgian fishermen abut reduced catch quality during spring blms, partly due t increased bycatch f sea gseberries (Pleurbrachia pileus) and ther jellyfish species. Especially the clgging by barrel jellyfish (Rhizstma ctpus) in the nearshre area (fig. 11) is imprtant in the light f integrated castal zne management, since these bservatins are directly linked t the quality f the swimming water and can be used as indicatins r warnings fr beach infestatins. 15

18 Figure 11. Catch n bard f a fishing vessel, featuring large barrel jellyfish (sept. 2012, cpyright Philippe Gdfrid) Jellypress versus jellyperceptin The secnd aim f this study was t identify the influence f the press n public jellyfish perceptin. The study results seem t indicate that perceptin is nly partly driven by the press if it cmes t jellyfish. Persnal experience seems t be at least equally imprtant as driver. Gershwin (2013) wrte that T mst peple, jellyfish prblems are abut stings. The public health aspects f jellyfish blms can be persnally stressful and can greatly impact turism.. This is cnfirmed by the results f ur survey, and especially by the analysis cncerning the frame f mind during a jellyfish encunter, and the key wrds given by turists. The latter were almst cmpletely fcused n negative aspects such as stings and the smell, while key wrds related t ecnmic and eclgical cnsequences f blms were virtually absent frm the list. On the ther hand, cnsequences f blms were the main tpic in 71% f the articles in the press. Articles describing dramatic encunters with jellyfish made up 12% f all jellyfish related publicatins in the general media, but nne f them described dramatic encunters alng the Belgian cast. Cndn et al (2012) already stated that the general media prbably raises the general apprehensin tward jellyfish by publishing these dramatic and newswrthy stries. On the ther hand, the survey results f Baumann and Schernewski (2012) in Germany shwed that the public was well-aware f the fact that there were n life-threatening jellyfish in the area. This is prbably als the case fr turists at the Belgian cast. Anther difference between press and public is the perceptin f an increase in the number f jellyfish (table 3). Mst articles in the Flemish, but als in the French general media (Bnnet, 2013) indicate a reginal and/r glbal jellyfish increase and the rise f slime is presented as a fact. In cntrast, the survey results shwed that nly 10% f the respndents perceived an increase in jellyfish, thereby relying n their persnal bservatins r admitting t their lack f attentin t trends in jellyfish numbers. This is similar t the results in Bnnet (2013), in which the majrity f respndents did nt perceive an increase. Anther emerging issue in the press vs. perceptin cmparisn is related t the identificatin f jellyfish species. While 50% f the media articles specifies ne r mre jellyfish species, differences between species are unknwn t mst respndents, especially t beach turists (table 3). Cnsequently, species-specific infrmatin prvided by the media is nt assimilated in the general knwledge abut jellyfish. Other infrmatin, such as causes, threats, cnsequences f and slutins 16

19 fr jellyfish prblems is similar in the Flemish media and in the survey results. Fr this type f infrmatin, the media des seem t have an influence n the public knwledge. This seems lgic, since this infrmatin can hardly be derived frm persnal experience, while the general media is used as the main surce f infrmatin by the majrity f the public. Table 3. Summary f the cmparisn between press infrmatin and public perceptin cncerning jellyfish and their blms jellypress jellyperceptin species species specific in abut 50% f articles general, except fr results f divers perceptin n jellyficatin increase nly 10% f respndents perceive increase key wrds tp 10 washed ashre, verfishing, pisn, beach, wind, sting, ful, slime, nuisance, danger, sea, glbal warming, warmth, swim, infestatin, turist tentacles, pain, transparent, fear mst imprtant causes Natural causes + glbal change & verfishing glbal change & verfishing mst imprtant threats fisheries & turism fisheries & turism best slutins jellyfish remval and cnsumptin stp verfishing and pllutin, jellyfish fishing Relevance t integrated castal zne management and research The cumulative impact f multiple human activities causing mre-frequent jellyfish blms is likely t require a multifaceted integrated management respnse (Richardsn et al, 2009), which shuld be based n quantitative data n the public perspective f jellyfish and hw jellyfish influence sciety (Kaneshir-Pinheir, 2013). In Eurpe, an integrated framewrk exists thrugh the prcess f Integrated Castal Zne Management (ICZM). Its implementatin is based n eight principles (2002/413/EC), f which especially the principle abut the invlvement f all parties cncerned is imprtant in the cntext f jellyfish and jellyperceptin. In this study, we fund that there is a large variatin amng surveyed grups in perceptin cncerning jellyfish presence, and in the reactins and emtins they evke. Cnsequently, it is imprtant t extend perceptin surveys t all grups directly and indirectly affected by jellyfish. By ding s, pprtunities may emerge fr cperatin between scientists, plicymakers and public parties. Ber (2013), fr example, described citizen science as an alternative methd t evaluate the presence and abundance f gelatinus zplanktn, with gd results in the Mediterranean (e.g. and Spt the jellyfish at Since the current study indicates that the public relies n persnal bservatins and experiences with jellyfish, these bservatins can be used as a mnitring tl r alert system fr jellyfish alng the Belgian cast as well (e.g. thrugh a smart phne app fr swimmers; Gershwin, 2013). Fr retrspective analyses, hwever, public memry has prven nt t be very useful, since peple s memries are highly influenced by their present perceptin. Mre specifically, Baumann et al (2012) fund that the answer t the questin f increase during the last five years was influenced by the amunt f jellyfish in the water at the time f the interview. Of curse, science based n citizen perceptin and knwledge is nt an ptin if participants are unfamiliar with jellyfish eclgy r differences between species. This is yet anther reasn why ne f the first management actins cncerning jellyfish increases shuld be the prvisin f species-specific infrmatin, fr example by distributing leaflets and putting up warning bards n the beach. This wuld likely result in a higher acceptance f jellyfish (Baumann & Schernewski, 2012), a better cmmunicatin between scientists and the public (Bnnet et al, 2013) and in a better quality f data in citizen science prgrams (Ber, 2013). 17

20 Cmmunicatin abut jellyfish is a cping strategy and can be rganized n a lcal r reginal level. Of curse, such cmmunicatin measures d nt reslve the jellificatin issue. Since there is a significant relatinship between jellyfish blms, human activities and envirnmental perturbatins (Brtz, 2011; Purcell, 2012), and since the Belgian part f the Nrth Sea is increasingly and intensively used fr many human activities, it is likely that jellyfish blms f lcal and nn-indigenus species will ccur even mre ften in the future. Cnsequently, drafting a management plan featuring mitigating strategies is a necessary next step, which, given the transbundary nature f the prblem, shuld be tackled n an internatinal level and shuld address all underlying causes, as was indicated by the survey results. Mnemipsis leidyi? Althugh this study was triggered by the presence f Mnemipsis leidyi in Belgian waters, the jellyperceptin survey was generalized t jellyfish fr practical reasns. Still, specific results n M. leidyi are wrth discussing as this cmb jelly species can pse a serius threat t the pelagic ecsystem and the anthrpgenic activities in the Belgian part f the Nrth Sea (Van Ginderdeuren et al, 2012). M. leidyi ften appeared in general media articles in Flanders in the past few years, but is still unknwn by the public because peple are unaware f any direct cntact. The species des nt sting, it is incnspicuus when washed ashre r caught in a net, and the chance f catching it in a fishing net is small due t its size and fragility. Hence, this species is nt likely t have a direct impact n beach turism r fisheries at sea, even when numbers wuld increase. Of curse, indirect effects n fisheries as a result f cmpetitin and predatin (Hamer et al, 2010), are still pssible. Additinally, unlike mst beach turists, divers d recgnize M. leidyi and they perceived an increase ver the last 5 years. Hence, the mnitring f the presence and abundance f this species, and f ther jellyfish (fig. 12), can be aided by gathering diver bservatins in a citizen science initiative (e.g. the Stichting Anemn initiative at Figure 12. Diver with Chrysara hysscella (cpyright Peter H. van Bragt) 18

21 References Baumann, S. (2009) Quallen an Deutschen Ostseeküsten Auftreten, Wahrnemung, Knsequenzen. IKZM-Oder Berichte 59. Universität Rstck ISSN Baumann, S.; Schernewski, G. (2012) Occurrence and public perceptin f jellyfish alng the German Baltic Castline. Jurnal f Castal Cnservatin, 16 (4): Ber, F. (2013) Review f jellyfish blms in the Mediterranean and Black Sea. Studies and reviews N 92. General Fisheries Cmmissin fr the Mediterranean. FAO. ISSN Bnnet, D. (2013) GELAMED Etude du Planktn Gelatineux sur la facade Mediteranéenne. Prgramme Liteau, Prgramme 189. Rapprt du synthèse. 106 pp + annexes Brdeur, R.D.; Mills, C.E.; Overland, J.E.; Walters, G.E.; Schumacher, J.D. (1999) Evidence fr a substantial increase in gelatinus zplanktn in the Bering Sea, with pssible links t climate change. Fisheries Oceangraphy 8 (4): Brtz, L.; Cheung, W.W.L.; Kleisner, K.; Pakhmv, E.; Pauly, D. (2012) Increasing jellyfish ppulatins: trends in large marine ecsystems. Hydrbilgia, 690 (1): 3-20 Ciantar, M. (2012) Investigating the sci-ecnmic impact f jellyfish utbreaks in small island states. MA dissertatin, University f Malta, 156pp. Cndn, R.H.; Graham, W.M.; Duarte, C.M.; Pitt, K.A.; Lucas, C.H.; Haddck, S.H.D.; Sutherland, K.R.; Rbinsn, K.L.; Dawsn, M.N.; Decker, M.; Mills, C.E.; Purcell, J.E.; Malej, A.; Mianzan, H.; Uye, S.; Gelcich, S.;madin, L.P. (2012) Questining the Rise f Gelatinus Zplanktn in the Wrld's Oceans. BiScience, 62 (2): Gershwin, L.A. (2013) Stung! On jellyfish blms and the future f the cean. University f Chicag Press. 456 pp. ISBN Hamer, H.; Malzahn, A.; Bersma, M. (2010) The invasive ctenphre Mnemipsis leidyi: a threat t fish recruitment in the Nrth Sea? Jurnal f Planktn Research, 33 (1): Kaneshir-Pineir M.Y. (2013) Jellyfish-human interactins in Nrth Carlina. PhD dissertatin. East Carlina University. 196 pp. Licandr, P.; Cnway, D.V.P.; Daly Yahia, M.N. ; Fernandez de Puelles, M.L. ; Gasparini, S. ; Hecq, J.H.; Tranter, P.; Kirby, R.R. (2010) A blming jellyfish in the nrtheast Atlantic and Mediterranean Bilgy letters, 6: Maes, F.; Schrijvers, J.; Vanhulle, A. (Ed.) (2005). Een zee van ruimte: naar een ruimtelijk structuurplan vr het duurzaam beheer van de Nrdzee (GAUFRE). Belgian Science Plicy: Brussel. 204 pp. Nastav, B.; Malej, M.; Malej, A. Jr; Malej, A. (2013) Is it pssible t determine the ecnmic impact f jellyfish utbreaks n fisheries? A case study Slvenia. Mediterranean Marine Science, 14(1): Purcell, J.E.; Uye S.; L, W.T. (2007) Anthrpgenic causes f jellyfish blms and direct cnsequences fr humans. Marine Eclgy Prgress Series, 350: Purcell, J.E. (2012) Jellyfish and ctenphre blms cincide with human prliferatins and envirnmental perturbatins. Annual Review f Marine Science, 4:

22 Richardsn, A.; Bakun, A.; Hays, G.; Gibbns, M. (2009) The jellyfish jyride: causes, cnsequences and management respnses t a mre gelatinus future. Trends in Eclgy & Evlutin, 24 (6): Schaafsma, M.; Luisetti, T.; Turner, R.K. (2013). Ptential ecnmic impacts f jellyfish invasins alng the English cast, with a special fcus n Mnemipsis leidyi. Prject MEMO, CEFAS reprt, 47pp. Van Ginderdeuren, K.; Hstens, K.; Hffman, S.; Vansteenbrugge, L.; Senen, K.; De Blauwe, H.; Rbbens, J.; Vincx, M. (2012) Distributin f the invasive ctenphre Mnemipsis leidyi in the Belgian part f the Nrth Sea. Aquatic Invasins, 7 (2):

23 Annexes 1/ turism industry survey 2/ fishermen survey 3/ pwer plant survey 4/ list f jellyfish articles in the Flemish general media 21

24 Interviewer: Plaats: Datum: Duur: KWALLEN: een sci-ecnmische studie Het Instituut vr Landbuw- en Visserijnderzek is cördinatr van het internatinale prject MEMO dat de verspreiding van kwallen en kwalachtigen bestudeert aan de Belgische, Franse en Engelse kusten. Om een inschatting te kunnen maken van de gevlgen van stijgende aantallen kwallen vr ecnmische en sciale activiteiten, vragen wij u m een aantal vragen te beantwrden. Uw gegevens en antwrden wrden vertruwelijk behandeld en blijven geheel anniem. Alvast bedankt vr de medewerking. 1/ Vreerst vragen wij enkele persnsgebnden gegevens ndig m uw antwrden te verwerken. Geslacht Man Vruw Leeftijd 18 tt tt tt tt Uw relatie met de kust:

25 beleid - bestuur cmmercieel Recreant/terist Uw berep (ptineel):.. VRAGEN VOOR ALLE DEELNEMERS 2/ Kan u vijf wrden pgeven die in u pkmen bij het hren van het begrip kwal / Heeft u de laatste vijf jaar kwallen gezien in zee f p het strand? Ja Nee Ik let daar niet p 4/ Heeft u de indruk dat er meer kwallen zijn dan vreger? Ja Nee Ik let daar niet p Indien psitief, he grt schat u die stijging in? Omcirkel. Verdubbeling x5 x10 x100 x geen idee 5/ Hiernder krijgt u een aantal stellingen. Antwrd met Ja, een beetje, nee : Wanneer ik een grte heveelheid kwallen (zu) zie(n), vel ik mij. Kalm Zelfzeker Gespannen Op mijn gemak Op mijn hede Angstig Nerveus ja Een beetje Nee

26 Ontspannen 6/ Bent u p de hgte van de rzaken van de stijging van het aantal kwallen? (kruis aan) JA De pwarming van de aarde/ klimaatsverandering. De verzuring van de ceanen De verbevissing van de natuurlijke vijanden van kwallen De zeldzaamheid van zeeschildpadden Vervuiling Transprt van kwallen via ballastwater van schepen De natuurlijke weerbaarheid van kwallen (snelle vrtplanting, pprtunisme in veding) NEE wenst u beter geïnfrmeerd te wrden? Omcirkel JA NEE 7/ Wanneer u nadenkt ver de kwallenprblematiek, dan vind u dat (mcirkel het best passende cijfer) U er niks mee te maken heeft alles van u afhangt Het alleen u aanbelangt het een wereldprbleem is Het een klein prbleem het van grt belang is 8/ Wie zal vlgens u het meest geraakt wrden dr een stijging van het aantal kwallen (slechts 1 antwrd mgelijk)? Omcirkel. 1. De teristische sectr (campinguitbaters, restauranthuders, ) 2. Inwners van kustgemeenten 3. Lkale verheden 4. De visserij- en aquacultuursectr 5. Teristen en recreanten 9/ Welke mgelijke plssing van het kwallenprbleem lijkt u de meest deltreffende?: Kwallen pvissen en verwerken (medicijnen, csmetica, veding,..) De verbevissing van bepaalde vissrten aanpakken Zwemznes afbakenen met kwallennetten De tever van vedingsstffen naar zee, waar kwallen van prfiteren, verminderen dr waterzuivering 10/ Wie met maatregelen tegen kwallenbleien financieren:

27 De verheid De visserijsectr De teristische sectr De maatschappij (via belastingen) GEDEELTE TOERISTEN EN RECREANTEN 11/ In welke peride is vakantie en recreatie aan zee vr u het belangrijkst? Gelijk het hele jaar dr Januari tt maart April tt juni Juli tt september Oktber tt december 12/ Welke activiteiten vert u vral uit aan zee en p het strand? Wandelen lpen Zwemmen Varen surfen Vissen Znnen Andere: 13/ Zu u uw activiteit aan het strand f p zee verderzetten indien er grte heveelheden kwallen zuden zijn (meer dan 10 kwallen zichtbaar)? Ja Misschien Nee BIJ NEE: 14/ Zu u uw activiteiten verderzetten indien u zu weten dat het m ngevaarlijke kwallen gaat? Ja Misschien Nee 15/ Zu de aanwezigheid van grte heveelheden kwallen een reden kunnen zijn m uw vakantiebestemming f vrijetijdsbesteding te wijzigen? Ja Misschien Nee 16/ Als er een stijging van het aantal kwallen zu zijn, he grt zuden nderstaande gevlgen vlgens u zijn? Omcirkel vr elk criterium het getal dat het best uw inschatting weergeeft.

28 Kwallenbeten bij baders en zwemmers Verwaarlsbaar belangrijk De sluiting van stranden en zwemwater vr teristen Verwaarlsbaar belangrijk GEDEELTE PROFESSIONELEN (COMMERCIEEL) 17/ In welke peride is uw prfessinele activiteit aan zee vr u het belangrijkst? Gelijk het hele jaar dr Januari tt maart April tt juni Juli tt september Oktber tt december 18/ Als er een stijging van het aantal kwallen zu zijn, he grt zuden nderstaande gevlgen vlgens u zijn? Omcirkel vr elk criterium het getal dat het best uw inschatting weergeeft. Kwallenbeten bij baders en zwemmers Verwaarlsbaar belangrijk Het verstppen van kelwaterinlaten van hydr-elektrische en nucleaire installaties Verwaarlsbaar belangrijk De beschadiging van visnetten Verwaarlsbaar belangrijk Sterfte van schelpdieren in aquacultuurinstallaties (esters, msselen) Verwaarlsbaar belangrijk Een daling in aantallen van cmmerciële vissrten Verwaarlsbaar belangrijk De sluiting van stranden en zwemwater vr teristen Verwaarlsbaar belangrijk 19/ Geef vr elk van nderstaande criteria aan he grt de risc s van stijgende kwallenaantallen zuden zijn vr verschillende sectren (mcirkel het cijfer dat best bij uw inschatting past):

29 Risic p een daling van de pbrengsten vr de visserij en de schelpdierenkweek Laag hg Risic p een daling van de pbrengsten van het kustterisme Laag hg Risic p de aantasting van het imag van de kustregi en de lkale prducten Laag hg Risic p materiële schade (vb schade aan visnetten) Laag hg GEDEELTE BELEID 20/ Als er een stijging van het aantal kwallen zu zijn, he grt zuden nderstaande gevlgen vlgens u zijn? Omcirkel vr elk criterium het getal dat het best uw inschatting weergeeft. Kwallenbeten bij baders en zwemmers Verwaarlsbaar belangrijk Het verstppen van kelwaterinlaten van hydr-elektrische en nucleaire installaties Verwaarlsbaar belangrijk De beschadiging van visnetten Verwaarlsbaar belangrijk Sterfte van schelpdieren in aquacultuurinstallaties (esters, msselen) Verwaarlsbaar belangrijk Een daling in aantallen van cmmerciële vissrten Verwaarlsbaar belangrijk De sluiting van stranden en zwemwater vr teristen Verwaarlsbaar belangrijk 21/ Op welk niveau denkt u dat een stijging van het aantal kwallen het meeste impact zal hebben? Omcirkel Persnlijk Lkaal Reginaal glbaal

30 22/ Geef vr elk van nderstaande criteria aan he grt vlgens u de gevlgen van stijgende kwallenaantallen zuden zijn (mcirkel het cijfer dat best bij uw inschatting past): Risic p een daling van de pbrengsten vr de visserij en de schelpdierenkweek Laag hg Risic p een daling van de pbrengsten van het kustterisme Laag hg Risic p preventieksten (vb waterzuivering, kwallennetten) Laag hg Risic p de aantasting van het imag van de kustregi en de lkale prducten Laag hg 23/ Op welk beleidsniveau met er vlgens u priritair actie wrden ndernmen m een stijging van het aantal kwallen tegen te gaan? (slechts één mgelijkheid aankruisen) Lkaal Reginaal Natinaal Glbaal Hartelijk bedankt vr uw medewerking. Indien dit nderwerp u interesseert, verwijs ik u graag naar de website van het prject

31 KWALLEN EN VISSERIJ: een risicanalyse Het Instituut vr Landbuw- en Visserijnderzek is cördinatr van het internatinale prject MEMO dat de verspreiding van gelatineus zplanktn bestudeert aan de Belgische, Franse en Engelse kusten. Om een inschatting te kunnen maken van de gevlgen van stijgende aantallen kwallen vr de visserij, vragen wij u m een 30-tal vragen te beantwrden. Dit zal ngeveer 15 minuten duren. U kan erp vertruwen dat uw antwrden vlledig anniem blijven en dat de gegevens p een vertruwelijke manier zullen wrden behandeld. Alvast bedankt vr de medewerking. Interviewer: Datum interview: Plaats interview: SECTIE 1: ACHTERGRONDINFORMATIE 1. In welke regi s vist u/uw vaartuig meestal? Vb. Ierse Zee, Keltische Zee., 2. Helang vist u reeds in die regi s? 3. Wat zijn uw delsrten (p jaarbasis bekeken)? 4. Met welk type vaartuig vist u (lengte & capaciteit)? Met welk vistuig vist u (evt. verschillend drheen het jaar)? 1

32 5. In welke perides vist u? Het hele jaar Specifieke maanden: SECTIE 2: ERVARING MET KWALLEN 6. Heeft u al een kwallenblei (grte cncentraties kwallen) meegemaakt? ja ga naar vraag 8 nee ga naar vraag 7 7. Heeft u al van cllega s gehrd dat ze een kwallenblei zagen? ja. Heeft u cntactgegevens van deze cllega s zdat wij hun deze vragenlijst kunnen vrleggen? Naam, telefn, Ga vervlgens naar sectie 3 rute A Nee Ga naar sectie 3 rute A 8. Vr elk cntact met een kwallenblei, kan u infrmatie geven ver a. Wanneer u die blei heeft waargenmen? b. Waar u die blei heeft waargenmen? c. He lang de blei duurde? d. Welke srten kwallen u heeft gezien? [zie ft s] Blei 1 Blei 2 Blei 3 Blei 4 peride Lcatie Duur srt 9. Heeft u it de Amerikaanse ribkwal (M.leidyi) gezien? [zie ft s] Ja Nee 2

33 10. Zijn er regi s die u in bepaalde perides vermijdt mwille van kwallen? Z ja, welke regi s en in welke perides? Ja Ik vermijd het gebied van Het gaat vral ver de peride Nee 11. Hebt u gedurende de laatste 10 jaar zelf een stijging in het aantal kwallen waargenmen? Ja ga naar vraag 12. Nee ga naar sectie 3 Rute B Of C 12. Kan u de verandering in kwallenaantal meer specifiek beschrijven? verandering in srten [zie ft s]: Meer individuen van vlgende srten: Nieuwe srten: nieuwe lcaties f perides: andere: Ga naar sectie 3 Rute B f C 3

34 SECTIE 3: DE INVLOED VAN KWALLEN OP DE VISSERIJ Vr de interviewer: vlg rute A, B f C A: het antwrd p vraag 7 was NEE : de persn in kwestie en zijn cllega s hebben geen ervaring met kwallenbleien B: het antwrd p vraag 7 was JA : de persn in kwestie heeft verhalen gehrd van cllega s ver kwallenbleien, maar heeft er zelf geen ervaring mee C: de persn in kwestie is reeds in aanraking gekmen met kwallenbleien A. Lees de vlgende tekst vr: Gedurende de laatste jaren zijn er een aantal meldingen geweest van kwallenbleien in Eurpese kustwateren, k in België. Klimaatsveranderingen kunnen leiden tt een stijging van de watertemperatuur, waardr kwallen meer kans hebben m nze wateren binnen te dringen en bleien te verrzaken. Zelfs als u ng niet in aanraking bent gekmen met dergelijke kwallenbleien, kan u ns helpen inschatten wat de gevlgen zuden kunnen zijn van dergelijke bleien p uw werk. Ga naar vraag 13 en stel de vlgende vragen in hypthetische vrm (wat als ). B. Stel vraag 13 en verder ver he de kwallen het werk van cllega s beïnvledden. C. Stel vraag 13 en verder ver eigen ervaringen met kwallenbleien: De vlgende vragen gaan ver de invled van kwallen p de visvangst en verwerking. 13. Wat waren de belangrijkste effecten van kwallen p het verlp van uw visserijactiviteiten (meerdere antwrden mgelijk) kleinere vangst dr veel kwallen in het net kleinere vangst dr minder vis in het gebied vissen werd nmgelijk wegtrekken naar een andere visgrnd bemanningsleden werden gestken dr kwallen het net werd beschadigd het srteren van de vangst duurdere langer andere (specifieer) 14. Welke maatregelen heeft u genmen m deze effecten te verminderen? 4