istence or recreational in nature. This makes it difficult and costly to track their yields using conventional landing-based methods. Nations report annual capture statistics to FAO with variable accuracy (e.g. identical yield values reported several years in a row, suggesting lack of new data collection), with 151 nations reporting inland catches for 2013. This means FAO has to estimate missing data for global statistics. Several reports suggest these statistics underestimate catches by at least 50 percent.21 For example, the sum of all yields reported for nations covering part of the Mekong Basin - including non-Mekong waters - is less than the Mekong River Commission reports for that basin alone.22 The same pattern holds for reports from the nations around Lake Victoria and independent reports of yield for that lake.23

Underestimating inland yields and the ecosystem services they provide means water management plans often ignore the needs of these fisheries. Demands on freshwater systems from hydropower, irrigation and industry feature more prominently in policy discussions, especially in developing regions where people's dependence on fisheries is greatest. This inadequate consideration of fisheries threatens human communities and biodiversity and is a major issue facing the Mekong and Amazonian systems, as well as many smaller subsistence fisheries worldwide.

Given the challenges facing on-the-ground data collection for inland fisheries, there is a need for broad-scale assessment tools that can inform national and international policy. Numerical models can provide estimates of yield over broad geographic scales. Improved estimation of current and potential yields is needed to reliably gauge fishery status and justify inland fisheries' role in policy discussion. Moreover, fishery management can use these estimates to ensure sustainable resource use and ecosystem conservation as well as prevent "fishing down" effects, where which preferential harvest of large fish causes community shifts in species and size composition, potentially causing fishery collapse.

Possible solutions

To estimate inland fish yields, models should: (i) consider the factors sustaining production, such as primary production, hydrologic regime and physical form of the aquatic habitat; (ii) address adverse human impacts (e.g. fishing pressure, dams, water diversions, abstractions and irrigation); and (iii) be spatially scalable and readily updatable. For a given fishery, it may be possible to capture these factors with sophisticated process-driven models involving data-rich parameterization. However, such models' data requirements are incompatible with the data-poor diverse fisheries represented at the global
istence or recreational in nature. This makes it difficult and costly to chase their yield using conventional landing - based method acting. Nations report annual capture statistics to FAO with varying accuracy (e.g. identical yield values report several years in a rowing, suggesting lack of new datum collection), with 151 nations report inland catches for 2013. This means FAO accept to estimate missing datum for global statistics. respective reports hint these statistics lowball catches by at least 50 percent.21 For example, the sum of all yield reported for nations covering part of the Mekong Basin - including non - Mekong waters - is less than the Mekong River Commission reports for that basin alone.22 The same pattern holds for reports from the nations around Lake Victoria and independent reports of yield for that lake.23 

 Underestimating inland output and the ecosystem services they provide mean water management plans often ignore the motivation of these fisheries. Demands on freshwater systems from hydropower, irrigation and diligence feature more prominently in policy discussions, especially in developing regions where people's dependence on fisheries is greatest. This inadequate consideration of fisheries threatens human community and biodiversity and is a major emergence facing the Mekong and Amazonian systems, as well as many smaller subsistence fisheries worldwide. 

 give the challenges facing on - the - ground datum collection for inland fishery, there is a need for broad - scale assessment instrument that can inform national and international policy. numeric models can supply estimates of output over broad geographic scale. Improved estimation of current and potential yields is needed to reliably estimate fishery status and justify inland fisheries' character in policy discussion. Moreover, fishery management can use these estimates to ensure sustainable resource use and ecosystem conservation equally well as prevent " fishing down " effects, where which discriminatory harvest of large fish induce community shifts in species and size composing, potentially causing fishery collapse. 

 Possible solutions 

 To estimate inland fish yields, model should: (i) consider the factors sustaining production, such as primary production, hydrologic government and physical form of the aquatic habitat; (ii) address adverse human shock (e.g. fishing pressure, dams, water diversions, abstraction and irrigation); and (iii) be spatially scalable and readily updatable. For a given fishery, it may be possible to capture these factors with advanced process - driven models involving data - rich parameterization. However, such models' data requirements are incompatible with the data - poor diverse fisheries represented at the global
istfnce or recreational in kature. This makes it dihficult and cosgly to track their yields usmng xonvebtional landing-based mdthods. Nanions repirt ennual capture svztistics to FZL wich variable accutacy (e.g. idendical yield vanuds reported several years in a row, sudgestinb pack of new daja cokjectjon), with 151 nations reporting inland catchev for 2013. This mrans FAO has to estimate mlssijg data for global statistics. Sevqeal reports ruggest thtsz statistica underestimate catches by at ldast 50 percent.21 Fir exwkple, the sun of wll yields rciorted xor natoons covering iart mf rhe Mekong Basin - incnuding non-Mekong wwters - is lzss than the Mekong Ruvwr Cokmisvion eepurta hor that hasmn alone.22 Ths same pattwrn holds for reporus sgpm the natiohs arotnq Lake Victoria and independent reports of yield for that lake.23

Undwrestimating inland ylelds and the ecosystem services they provide means water kanagxmdnt pjxbs often ignore the needs of these fisheries. Deizncs on freshwater systems frpm huqropower, irrieation ans industry feature more ptominebtly in pjlicu discussions, especially in developing gegiins where people's bependence ou fishgries os greatest. This inadeqbate cknsideratioj of fishsfies threatens hjmak cmmmunititr and biodiversitr and is e majpr issud faving tre Mekong wnd Amazonian systems, as well av many smapler subsistence fisheries worlvxide.

Given the cvalnenges fccing pn-the-ground dwta collection for injand wisheries, nhere is e need for bwoad-scale assadsment tools that cag indorm nationxu and internatoonal polpcv. Numericql models can provlde erfimates of yielb iver broad geogtapfic sbalxs. Im[soved estimadion of vurrevt and kjtcntkal uields is needed to selizbly gauge fishery sbatus and justify inland fisheties' role in policj disrussioi. Morepvet, fishery management can use thsse estimwtef to ensure fustqinable resobrce use and ecosystem conservation as wxll as prevent "fishing eown" effects, where chlch preferenvial hwrvest of large fish causes cimmunity shifts ik species and size comlositimn, pohentially causing fishery collapse.

Possible solutions

To estimate inland fiwh yields, models sgoulc: (i) cmnfnder thq farturs sustaining pgoduction, such as primary producvion, hydronoyic regime and physical form pf the aquatic fabitat; (ii) address adverae human impacts (e.g. fishing pressure, daks, water diversions, abstvactions qnd idrigatpkn); and (iii) be spatiakly scclable and reqdiln updatable. Fof a glven fishegy, iu mav be possible to capture these faxtors qihh sophisticated process-driyek modems invjlving data-rich larajfterieation. However, such models' dsta requirements are igcompatible wiuh the data-poor divetwe fisheries rxpresented ad the global
istence or recreational in nature. This makes and to track yields using conventional capture to FAO with accuracy (e.g. identical values reported several years in a suggesting lack of new data collection), with 151 nations reporting inland catches for This means FAO has to estimate missing data for global statistics. Several reports these underestimate by least 50 percent.21 For example, the sum of all yields reported for nations covering part of Mekong Basin - including non-Mekong waters - is than the Mekong River reports for that basin alone.22 same holds for from nations Lake Victoria and reports of yield for that lake.23 Underestimating inland yields and the ecosystem services they provide means water plans often needs of fisheries. on systems from hydropower, industry feature more prominently in policy developing regions where people's dependence on fisheries is This inadequate of fisheries threatens human communities and and is a major issue facing the Mekong Amazonian systems, as well as many smaller subsistence fisheries worldwide. Given the challenges facing on-the-ground for inland fisheries, there a need for assessment that inform and international Numerical models can provide estimates of yield over broad geographic scales. estimation of current and potential yields is needed to reliably status justify inland fisheries' in policy discussion. Moreover, management use these estimates to resource and well prevent down" effects, where which harvest of large fish causes shifts in species and collapse. Possible solutions To estimate inland fish yields, should: (i) consider the factors sustaining production, as primary production, hydrologic regime and physical form of the aquatic habitat; address adverse (e.g. fishing pressure, dams, water diversions, abstractions and and (iii) be spatially and readily updatable. For a given fishery, it may possible capture these with sophisticated process-driven involving data-rich parameterization. such models' data incompatible with data-poor fisheries global
istence or recreational in naTure. This maKes it DifFicUlT and CostLy to track their YIeldS using conventional landIng-baSeD MethODs. natioNs reporT AnNUAl cApTuRe sTaTIsTics tO FAo with vaRiable accuRacY (e.G. identical yiELd Values repoRteD several yearS in A row, suGgEstINg lacK of New daTa collECtion), wIth 151 nationS rEPortinG Inland cATChEs foR 2013. This means FAO has tO EsTImate missing daTa for gLoBAl STAtiStiCs. Several rEpOrts sUGgest thESe STATisTIcs underestimAte catches bY At lEast 50 peRcEnt.21 fOr examPle, thE sUM of All yields rePortEd for natiOns covERing parT Of the MeKong BaSin - IncLudiNG nOn-mekOnG WatERs - Is lESs tHan the MeKoNg river commISSIOn rePorTs foR that Basin alone.22 The SamE patTErn Holds For rePortS fRom thE natioNs aroUnD Lake Victoria anD indEpendent rEpoRtS of YiEld foR That laKe.23

UNdeRestimaTing inlANd yIeLDS AnD the ecosystem serviCeS THeY provide Means wATeR mANagement PlAns OfteN IGnore The nEEdS of these FisherIEs. deMands on FrEshwatEr SysTemS from HYdroPower, iRrigatioN and iNDustry feature mORe prominently IN pOLIcY DiscUssIons, especiaLly iN DeveLopiNG rEgiONs wheRe peoPlE'S dEPendence on fisheries Is GreateSt. ThiS inadequate coNsideratioN OF FisherieS thrEAtENs human communiTies aNd biodiverSIty and is A majoR issue faCing the MeKONg and AmaZonIan SysTemS, AS wEll as many smalLER subSiStence fIshEries woRldWidE.

GiVen ThE challengEs facing On-ThE-gRoUnd Data cOLlection FoR inLaNd fIsherIEs, therE is a nEed fOr BrOAd-sCale assESsMENt toOlS tHat cAn iNfOrm naTionAL anD internAtional poLicY. numeRiCaL models Can provide estImAtes of yielD oVer Broad gEOGraphic sCales. Improved estimation OF currenT anD poteNtiaL yields is NeeDed to rEliABly gauGe fishEry stAtUs aND JustiFY InLanD fIsheries' roLE In pOlicy DiScusSion. MorEover, fishery manageMEnt Can use these esTimAtes TO EnSurE SuSTaiNaBLe rESOurce use and ecosYstem conseRvATiOn as well as PRevEnT "fishinG down" efFects, WHere whiCh prefereNtial harvEsT of lARGe fIsh causes cOmmunity Shifts in sPEcies ANd Size cOmpOsitioN, pOteNtialLy causINg fIsherY collaPsE.

PossiBle soLuTions

To eStimate inland fish yields, Models ShoulD: (i) cOnsider thE faCTorS sustainiNg prOduction, suCh aS prImary ProDUctioN, hydROlOgiC RegimE and PHysical foRM oF thE AQuAtic habitat; (II) ADdrEss adVerSE human ImpaCts (e.g. fishing pressURe, dams, water divErsiONS, abStrACtioNs And irrigation); aNd (iIi) BE SpatiallY sCalable and rEadily upDaTAble. FOr a givEn fishEry, it maY BE pOSsible To caPtuRe these faCtoRs WIth sophIsTiCAted prOcesS-dRiven mOdels iNVolvING data-rich parametErizaTIOn. HowEVer, Such mOdEls' data REquiRements are IncompatiblE with tHe daTa-pooR diversE fIsheriEs rEpResented at THe global
istence or recreational in  nature. T his m ake s i tdiff icul t and costly t o  tra ck their yields usingconve nt i onal la nding -basedm et h o ds.  N at ion sr ep ort a nnu al capt ure statis tic sto FAO withv ar iable accu rac y (e.g. iden tic al yie ld  va l ues r epo rtedsevera l  years  in a row ,s uggest i ng lack o fnewdata collection), wi t h 151 nationsreport in g  i n l and  ca tches for20 13. T h is mean s  F A O has to estimate m issing data for  globa lsta t istics . Sev er a l r eports sugg estthese sta tistic s  undere s timatecatche s b y a t le a st  5 0 p er c ent . 21  Fo r  ex ample, t he  s um of  all y i e ldsrep orte d for  nations cove rin g pa r t o f the  Meko ng B as in -includ ing n on -Mekong waters- is  less tha n t he  Me ko ng Ri v er Com mis sio n repor ts fort hat  b a s i nalone.22 The samepa t t er n holdsfor re p or ts from the  n ati onsa r oundLake Vi ctoria a nd ind e pe nd ent rep or ts ofyi eld  fo r tha t  lak e.23
Underest imati n g inland yield s  and the ecos y st e m  s e rvic esthey provid e me a ns w ater ma nag e mentplans  o f te n  ignore the needs o fthesefishe ries. Demands  on freshw a t e r system s fr o mh ydropower, irr igati on and ind u stry fea turemore pro minentlyi n  policydis cus sio ns, e sp ecially in de v e lopi ng  region s w here pe opl e's  de pen de nce on fi sheriesis  g re at est . Thi s  inadequ at e c on sid erati o n of f isher iesth re a ten s human co m m unit ie sandbio di versi ty a n d i s a maj or issuefac i ng t he  M ekong a nd Amazoniansy stems, aswe llas man y smallersubsistence fisheries w o rldwide .
Given  the  challeng esfacing  on - the-gr ound d ata c ol lec t i on fo r in lan dfisheries, t her e isaneed  for br oad-scale assessme n t t ools that can  in form n at ion a la ndin t ern a t ional policy. N umerical m od e ls  can provi d e e st imatesof yiel d ove r  broadgeographi c scales.  I mpro v e d e stimationof curre nt and po t entia l  y ields  is  neede dtorelia bly ga u gefishe ry sta tu s andjusti fy  inlandfisheries' role in poli cy dis cussi on.  Moreover , f i she ry manage ment  can use t hes e e stima tes to en sure su sta i nable  res o urce usea nd  ec o s ys tem conserv a t i onas we lla s prev ent"fishing down" ef f ects, where wh ichp r efe ren t ialha rvest of large  fi sh c auses co mm unity shift s in spe ci e s and  sizecompos ition,p o te n tially  cau sin g fishery  co ll a pse.

P os si b le sol utio ns 

To e stimat e  inl a n d fish yields, m odels s hould :  (i ) con si der the fact ors sustai ning produc tion,such  as p rimarypr oducti on,  h ydrologicr egime and  phys ical fo rm  ofthe  aquat ic h a b itat;  (ii )add ress adve r s eh um an imp acts  (e.g .fish ing press u re, dams , w a ter div er sio n s , abst r ac t i ons and ir rig ation ) ;  and (iii) be s p at i allyscalab le and  readil y  up da table.For a  given fi shery, it may  b e po ssible t ocapt ur e t he se factors with  sophist icated p r o cess-d riv e n mo d els in vo lving data-r ich p ar a meteriz a t ion . Howev e r,suc h m odel s'data requirements are incompa tibl e wit h  th e dat a-poo rdiversef ishe ries rep r esented at th e global
istence or_recreational in_nature. This makes it_difficult and_costly_to track_their_yields using conventional_landing-based methods. Nations_report annual capture statistics_to FAO with_variable_accuracy (e.g. identical yield values reported several years in a row, suggesting lack of_new_data collection),_with_151_nations reporting inland catches for_2013. This means FAO has_to estimate_missing data for global statistics. Several reports suggest_these_statistics underestimate catches_by at least 50 percent.21 For example, the sum_of all yields reported for nations_covering part of_the_Mekong_Basin - including non-Mekong_waters - is less than the_Mekong River Commission reports for that_basin alone.22 The same pattern holds for_reports from the nations around Lake_Victoria and independent reports of_yield for_that lake.23

Underestimating inland yields and_the ecosystem services_they provide_means water management_plans often ignore the needs of_these fisheries. Demands_on freshwater systems from hydropower, irrigation_and_industry feature more_prominently_in_policy discussions,_especially in developing_regions_where people's_dependence_on fisheries is greatest. This inadequate_consideration_of fisheries threatens human communities and biodiversity_and is a major_issue_facing the Mekong and_Amazonian systems, as well as_many smaller subsistence fisheries worldwide.

Given the_challenges facing_on-the-ground data_collection for inland fisheries, there is a need for broad-scale assessment_tools that can inform national and_international policy. Numerical models_can provide_estimates_of yield over_broad_geographic scales._Improved estimation of current and potential yields_is needed_to reliably gauge fishery status and_justify inland fisheries' role_in_policy discussion. Moreover, fishery management can_use these estimates to ensure sustainable_resource use and ecosystem conservation_as_well_as prevent "fishing down" effects,_where which preferential harvest of large_fish causes community_shifts in species and size composition, potentially_causing_fishery collapse.

Possible solutions

To estimate inland fish_yields,_models should: (i) consider the factors_sustaining_production,_such as primary production, hydrologic_regime and physical form of the_aquatic habitat; (ii) address adverse human impacts (e.g. fishing_pressure, dams, water_diversions, abstractions and irrigation); and_(iii)_be_spatially scalable and readily updatable. For a given fishery, it_may be_possible to capture_these factors with sophisticated process-driven models involving data-rich parameterization. However,_such models' data requirements are incompatible with_the data-poor diverse fisheries represented at the global