H(Tue Mar 03 09:33:22 2009) From FISHERY MGMT final for posting.vmfe,Q AA$7L|~~~$$$$$$BDhd' ~ 0lL}} ?  [   O       $|  B|o$%9%,(]'<,/| 1| 4%  |<(<4$ |;(D874p3|>,K | NC0Gp|W$Ui$$Y w6#$\L| ^V9R?|?c il| laIe@|C$x ||L eR|H$~[|4$N^?|?e "L%,9|_$ f  (6  $f  Q|G,hV?|?j Nn2|=,].?P|=F  h|Y(*B?l}L=0 a"(%P,|:,"p"e|R,sB;k,,%s|O 1-h|S,:T <@ 5 |7(@(|n$F^1"|6$J0|m,PL$Al|T$V?, YU$u5|@$`\| c.>Fn|V hgS|I {1x?|?d <'|^(/L*|9$v'B@E/!|B5 K  |P z+A|`$ +K $B ] $0* 'MD@E d|CQ  A|?k +lJ|E$ = $7 Q+fzDc @ |M C|D,G?|?f '.s4|?,#:|B$$GB?|?g +RZx/$7:|9|A$C]W4|\,K59U.!,MRJ|a Ui\ @Xtb|] ak9V|J,j 9B @ r=@@D&|=8 z*u|Z,R |[,8|N  \ @|l$r$?@ACm|?U Y |b$}=@\|=K B?|?h   E ,J=?Vv|=X R?|?i ||iL(|z7$l,0?l? %@??- lL= R%>l, ;l,( IWY/ ,a@l %|+|/<;'}$(5wT($:-,B8j+$BB'$Il| K2,Q( S 5 _| (W{ [ A?3 eQY8M&,rL>@]L=* uj=@Xw=. xaBOt-$}.q~1,BF' , J5i w, U#CF A,PGXzD) e?NL=' | +bL$+ aL$+L$ ?+DW $0 &! }L$,B yL$| I UC A(6.3#L, ?FfH(L$Ip7L$ t ?@@L? ! KrL$*r L(6Z?L$Dc ?L? LFL U,dBL$b   L p;l?@@IL? x_ l  L  \yL,  {L,T 6t ??L=  | ?L? I .\ ?L=  A $V| L D $    P   $#  ` $ Ju o:8 8 A  d{ $e  pB ? |p F/ J)| $ V | $ O @R-| =  "] *g|  *g ?AMs| ?  = ?| = j= | ^B ? ?} ' kJ U t,. '; s,7 v ?+ L=p D Jbz y,J$ J  (U> O N+ q$^ Jl8 #<Y 8u f3  @]0 r n J {$s 6' ~ M   v  .  |, Jo: #SMOOTH#value of catch catch Cselling price of fish-$ -Yearcumulative value of catchcumulative income per unitcurrent income per unit -unitsnet growth of fish stockadditions deaths-t*"SWITCH ecosys affects additions on-off" -dmnl.effect of ecosystem degradation on additionsIF THEN ELSELK eco effect on additions*fraction of ecosystem capacity remainingactual recruits&SWITCH on off seasonal recruitmentexpected recruitment amountreleased recruitment2Ecosystem Capacity for Biomass of Unfished Stock.MAXIMUM ECOSYSTEM CAPACITY for this stock*fraction of additions from recruitmentSWITCH to use fixed fraction2current fraction of additions from recruitment.FIXED FRACTION ADDITIONS FROM RECRUITMENTPotential RecruitmentRATE OF INCREASE rCurrent Fish Biomass B*constant additions due to recruitment.max stock size where recruit relation exists"modified rate of rec increase.LK fraction of additions from recruitment"mean age of biomass in the stockZIDZBiomass Timeton years leavingbiomass outton years enteringmonth within year MODULOcurrent time in months -monthsmonths per yearJFRACTION OF MAX POSSIBLE STOCK SIZE AND WHERE RECRUIT RELATION CHANGES.SWITCH ON OFF constant recruitment optionRecent Typical Fish Priceschanging fish priceBASE PRICE OF FISHBLK relation of cpue ratio to its effect on vessel replacementrevised replacement rate&Expected Rate of Vessel Replacementsmooth of cpue ratioMINMAX PRICE*TIME NEEDED FOR PRICES TO BECOME TYPICAL"expected rate new vessel entry"effect of cpue on vessel entryMAX POSSIBLE NEW VESSELS:LK effect of recent realtive income on acceptable cpueeffect on acceptable cpue:SWITCH to turn on effect of income on acceptable cpuecurrent income ratio*effect of biomass on g rate of increaseSwitch to use ALT growth.Para effect of biomass on g rate of increase.effect of biomass on bh g rate of increaserecent past income per unitcpueSHORT TERM CPUE SMOOTH TIME SMOOTH"RECENT PAST INCOME SMOOTH TIME"income adjusted acceptable cpueUNDERLYING ACCEPTABLE CPUECATCH FOR PRICE SMOOTH TIME&ratio of current to recent catchesXIDZrecent catch levels.LK effect that size of catch has on price SMOOTHI&time over which recruitment occursMONTHS OF SPAWNINGspawning period k growth"Switch to use Asymtotic growth&effective biomass of unfished stock p growth&Switch to use Asymtotic recruitment.price and cost .outputSum of Catch.capacity utilcapacity utilization2SWITCH ON OFF cpue affects capacity utilizationBASE CAPACITY UTILIZATION.effect of cpue ratio on capacity utilization"short term smooth of cpue ratiocpue ratio2LK effect of cpue ratio on capacity utilization.old age in stock.fish popdelayed recruitmentgrowth additionsmodified rate of g increaseaverage rate of increase-1recruit additionsMAXPink NoiseDELAY FIXED&YEARS PRIOR TO ENTERING FISH STOCK2feedback effect of biomass on recruitment rate k recru p recrunormal death fraction.ratio of current biomass to unfished biomasscatch fractionmodified gear efficiencyeffective fishing unitsINITIAL BIOMASSFEEDBACK EFFECT ON GROWTH.Management efforts*managements proposed vessel entry rate6management's proposed adjustments to gear numbersactual vessel entry rate"industry's desired entry rate*realized strength of management views2ratio of vessel entry difference to fleet size Units of Fishing Gear E6biomass ratio when ecosystem changes are not knownchange in perception"difference in status perception"TIME NEEDED TO CHANGE PERCEPTION"new perception of stock status.Management's Perception of the Fish Stock6effect of differences on management acceptability"switch - lobbying feedback""LK lobbying effectiveness lookup2effect of perception on proposed gear numbers6LK perception of stock vs fishing gear change lookupEXPECTED IMPLEMENTATION TIME"LK stock vs perception lookupperceived stock ratioratio to use"STOCK ASSESSMENT INACCURACIES"switch - use which ratio?""STRENGTH OF MANAGEMENT MANDATE:effect of historical catch level on management mandate.effect on ecosystemeffect on recovery time*LK effect on recovery time multiplierrecovering capacitylosing capacityECOSYSTEM LOSS RATE PER UNITpossible recovery amountRECOVERY TIME.noise componentChange in Pink NoiseWhite NoiseCorrelation TimeMeanNoise Seed&Standard Deviation for pink noiseRANDOM UNIFORM.gear efficiency2SWITCH on off effect of cpue on gear improvementimplemented improvements"effect of cpue on improvements2BACKGROUND FRACTION OF IMPROVEMENTS IMPLEMENTEDpossible improvement*Typical Recent Fishing Gear Efficiency"changing typical gear efficiencyINITIAL GEAR EFFICIENCY qCPUE RATIO AVERAGING TIMErecent changes2TIME FOR FISHING GEAR CHANGES TO BECOME TYPICAL6LK effect of cpue on implementation of improvementsSmooth of Recent CPUE Ratios&new maximum possible gear efficiency&POTENTIAL GEAR IMPROVEMENT FRACTION.vessel entryCPUE SMOOTH TIMEexpectation smooth timenet change in unit numbersentering fleetactually retiring from fleeteffect of cpue on retirement:LK relationship of cpue to increasing vessel retirementnormally retiring from fleet:LK relation of cpue ratio to its effect on vessel entry SMOOTH3&AVERAGE VESSEL LIFE SPAN IN FLEET"INITIAL NUMBER OF FISHING UNITS .Control".catch effect on mgmt politics2Switch ON OFF historical catch effect on mgmt:LK historical catch ratio effect on management lookup&ratio of short to long term catchshort term smooth of catchSHORT TERM SMOOTH TIMElong term smooth of catchLONG TERM SMOOTH TIME.recruitment loop SMOOTHINST SMOOTHIINSTINI SMOOTH3INSTLV2DLLV12#Expected Rate of Vessel Replacement>SMOOTH3#oo6#Expected Rate of Vessel Replacement>SMOOTH3>LV2#xp2#Expected Rate of Vessel Replacement>SMOOTH3>DL#i6#Expected Rate of Vessel Replacement>SMOOTH3>LV1#(n&#recent past income per unit>SMOOTH#o"#recent catch levels>SMOOTHI#UE.#short term smooth of cpue ratio>SMOOTHI#is*#Smooth of Recent CPUE Ratios>SMOOTHI#(c&#short term smooth of catch>SMOOTH#&#long term smooth of catch>SMOOTH#TH()#(OTHI(cpueratio,CPUERATIOAVERAGINGTIME,1)#N(OTH(catchC,SHORTTERMSMOOTHTIME)#&(OTH(catchC,LONGTERMSMOOTHTIME)#".FISHERY MGMT final for posting\7L 7LXXU  LlLL \$L' +L/ 4L 9\>LBlFL JL O 7L7Ld |   <    < , ||  |  l |l\  |\      <\\|, | , < \ < , L <|l<, < ,  l \<\\| ,|, | |  ||\ ,|, | < , \ L\   l \ \|L <\ | <| <<\,LL  < | L    ,   ,\<  ,  |ll  , \\    \ L,   ,  ||  |Ll l   L <l|  l r$ UTimes New RomanMdTITLE PAGEZL$@ UTimes New Roman dGetting Startedd|$ UTimes New RomandModeling ConventionsZt$ UTimes New RomanvMODEL: Fish PopulationQ=$ UTimes New Roman.dMODEL: Feedback effects on additions$ UTimes New Roman8dMODEL OPTION: Spawning season?\$ UTimes New RomandMODEL OPTION: constant recruitment?D~ UTimes New Roman[dMODEL: Units of Fishing GearKH~ UTimes New RomandMODEL: capacity utilizationdDL~ UTimes New RomanKdMODEL: Prices, income and desired cpueU/P~ UTimes New Roman8dMODEL: gear efficiencyZ1T~ UTimes New RomanCdMODEL: fishing effect on ecosystemRX~ UTimes New Roman\dMODEL: Management RoleQ\~ UTimes New Roman"dMODEL: Political Willd,`~ UTimes New Roman)dMODEL: mean age of biomass[Ԅd~ UTimes New RomandMODEL: recruitment fractione h~ UTimes New RomanAdOUTPUT + MAIN CONTROLSZll~ UTimes New RomandOUTPUT ManagementdLp~ UTimes New Roman"dOUTPUT Fishing Unitsdt~ UTimes New RomandOUTPUT: effect of pricesdwx~ UTimes New RomandOUTPUT: Recruitment y|~ UTimes New RomandOUTPUT: Mean Biomass Aged~ UTimes New RomandOUTPUT: CPUE + Catch vs Biomassd<~ UTimes New RomandOUTPUT: Gear Efficiency~ UTimes New RomandOUTPUT: Gear, Environmental effect of d~ UTimes New Roman,dMODEL: noise componentd %T|=P@Qbq;qZeq}JVjy@_H7L nj ) To use navigation buttons: First lock sketch - icon at upper left (@A. The fish population portion of this model is based on the "Schaefer" biomass dynamic model and models the population in terms of biomass. A.The number of fishing gear units entering the fishery is determined by the recent catch per unit effort (cpue) from the fishery. 3D+1) Optional feedback from biomass to additions so that the additions fraction can decrease as biomass increases, J0 2) Optional partitioning of additions into additions due to growth, and additions due to (possibly delayed) addition of new fish (i.e. recruitment).ZV >l#3) Optional addition of random "pink noise" to recruitment.NL Z@C: Entry and exit of fishing units.vs #Gear efficiency can, optionally, be increased as cpue drops below the acceptable level. P0There is also an option to allow for adverse effects of fishing on the ability of the ecosystem to support the fish population.JG _h @F. Management of the fishery  3.Management attempts to adjust fishing effort up or down depending on the relative stock size. Management attempts to keep the stock size at 50 percent (default) of the virgin stock size.RO  @G. Lobbying by fishers can also occur.fa  =@H. Political desire for better management can also vary. *] n1Relative strength of management views will vary based on lobbying by fishers. If difference between industry's desired rate and management adjustments is high then lobbying will be stronger and will weaken management's suggestions.  ,!The political mandate for management is stronger when current catches are low compared to recent historical catch levels l*,ArialA Basis for Understanding Fishery Management ComplexitiesB@ ;l= Fish Population BiomassB> mF! Units of Fishing Gear:8 @?# Management RoleJG I# Strength of Management MandateFA AoB! Changing Gear EfficiencyJG oI" Effect of Fishing on Ecosystem><  Output and ControlsB= m  Modeling conventionsfd S(Comic Sans MSThis Version: October 2007 vRecruitment additions to the population biomass can optionally be formulated as a Beverton and Holt type recruitment function in which the asymtote and steepness of the lefthand side of the curve can be set.}  6Growth additions to the population biomass can, optionally, be changed from the Shaefer model default (growth directly proportional to stock biomass) to a function that allows a lower growth rate as biomass increases. A second alternative is the use of a Beverton-Holt type relationship whereby growth additions approach an asymptote as biomass increases.^Z }#A background gear efficiency improvement can also be implemented.vs :#Use of existing fishing capacity can, optionally, be influenced by catch per unit effort. <(Entrance of new, and use of existing, fishing gear is determined by catch per unit effort (cpue) compared to an "acceptable catch per unit effort". VQ }@D. Changes in efficiency of fishing gearRO t@E. Effects of fishing on the ecosystem g0The initial value of fishing gear efficiency is set by the user. This is equal to the fraction of the biomass caught by a single fishing gear unit. bAdditions flowing into a standard Schaefer modeled stock are a constant fraction of the existing biomass already in the stock. There are several reasons why this may not be appropriate.vr #This is formulated as an effect per veesel per year on K the ecosystem carrying capacity.fc #It can be viewed as, for example, the effects of trawls on bottom habitat.jf  $This is done by adjusting the number of vessels that can enter the fishery. 4*Acceptable catch per unit will decline as inome levels decline. This will, for example, lower the threshold cpue at which vessels will enter or remain in the fishery.>: ;= Prices and IncomeB@ = Use of Fishing Capacity  D(ArialThe purpose of this model is to provide a thinking tool for those who are interested in the management of fisheries and the factors that make management of even a simple fishery complicated. F ArialAs currently written, the model assumes some understanding of fishery management issues.nj huFollowing is a brief description of various aspects of the model.NI 2Keep in mind that a biomass dynamic model is NOT usually used to model fish numbers. It is used to model biomass. As normally used, a single inflow of additions to the stock combines both 1) growth of fish in the stock and 2) additions due to to the addition of young fish, often called "recruitment." zv S@B. Acceptable (minimum) Catch per Unit Effort (cpue), income, and fish pricesFB 2The possibility of using seasonal recruitment has been added. That is, rather than entering the fishery continuously, new fish biomass can enter during a restricted part of the year. This modification has been done in such a way as to maintain the basic functionality of a biomass dynamic model..)  .) } VQ Fish prices are influenced by the amount of fish caught.jh 4"Fish price and cpue determine income per unit which influences acceptable cpue..) 1 .) 8 .)  .)  .)   .) y  .) ]   Q3 This model was developed with Vensim Professional. It can also be used with the free Vensim model reader and with the free Vensim PLE. If using PLE the clickable links will not work. In that case use the navigation tool at the lower left..)  NL 7VO click to see this part of the model:7 n To Get Started.)  " <;@8 " </@} FB UI click to see this output " A>@  .) 1 .) 6 .)  .)  .) Q  .) 6 b] *Because of this the following options were added to the basic model: S The most important of these is the fact that, in the standard model, the mean age of biomass at equilibrium does not change as fishing effort changes.zx !&(ArialRichard G. Dudley richard.dudley@attglobal.net O"See: Dudley, R. G. 2007. A Basis for Understanding Fishery Management Dynamics. System Dynamics Review. 23(4) (winter 2007)4 (8If~H7L:7 ?@ First Test Run>; 4]Go to the Output and Controls page>< t Output and ControlsB= `g6"RETURN to Title Pagero ($aClick on the synthesim icon at the top center of the page (the running man with lines)^Y DfChange the slider under UNDERLYING ACCEPTABLE CPUE to 30 t/year.VQ Type any name for a new model run in the white box above>< zMove any sliders -- for example....RN )See Help\Vensim Manuals\Model Reader Notes ..... etc.vq nOView alternate outputs / controls with clickable links or using navigation at lower leftB= Click the stop icon to stop the run.< :`p*;KYt~ZkH7L,,AB= ! Standard Conventions~z )"Stocks (also called state variables or levels) are in boxes with the Initial Letters Capitalized 4"Rates or flows represent a change of the associated stock with respect to time, and are shown by pipes, arrows, and valves>< 9Stocks can only be changed by flowsfb S-All other model components have no associated shape and are in lowercase.FD ;Model constants are (usually) all UPPERCASE^Z Y*=Arrows connect one model component to another that it influences.FB Y7  Other "Conventions" Used ZX a Lookup functions are in red and start with "LK" R A "ghost" variable is indicated within < > and is a duplication of a model component which appears elsewhere in the model. dK*(Smooth and delay functions are placed in a colored box without a border (indicating that they are actually proxies for stocks).B? +;H Model: Fish Population>; ;C Model: Management 63 :6"Title Pageje T To use these buttons: First lock sketch - icon at upper left&! /number a&! 0number b.+ lv number a- number b" + " -  SAlthough all model components have associated equations, labels on arrows give the diagram more meaning. J=Herein a + sign signifies that a change in the first component will change the second component in the same direction... all else being equal. A minus sign - signifies that the change will be in the opposite direction.JH W:ENavigation buttons have been added at the upper left or on the left side of the sketch. These allow navigation among views both when viewing and running the model. Make sure the lock icon (upper left) is selected. Alternatively one can use the software's navigation selections bar at the lower left.B? m=] Output & Control: Mainfc + Orange Boxes are clickable links to Output / Control pages^Y a0 Blue boxes are clickable links to model diagramsro GC* Blue edged boxes are clickable links leading to associated model views YS(ArialTo use clickable links in Vensim the sketch must be locked using the lock icon in the upper left. These links will not work in Vensim PLE. Lock is automatic in Vensim Model Reader Y$ Boxes a pale green background provide additional information pertaining to the current view. pS (Navigation among views is also possible by using the page up and page down buttons on the computer keyboard.+ *<N^p"-4=HQZalw &/6ALS\enw~(9Kdox)9JZagmx~H7LB@ bMe) to recruitment fraction>9 r/ effect on growthFA {I to effect on recruitmentFD {=b7 to changing gear efficiency>; NHR$to noise componentFA [mIY to units of fishing gearNK ogw@  to effect of fishing on ecosystem*( |o@-  0 "  "  dQ  0 "  j " d   0" <  0 " g " d   0 "   " ,0(" !+@ " + " +W *( l<  S." +j% *( Q. " +&E "  @  \1*( j@ *( G* " #"@me *( ,Lj$*( |LF=  d@+" '+ " '+@. " "+F  ,zP" +'+K " + @1@  8 *( \"@ *( <<- $ 0.+ *( \@-  " .+b " G!+ 2@V*( k_G0 " 6-@  I*( .O *( ,O  <G" 9; @ " :; @  " 8+ " 8!+x  ;*" !@@F &@@>*( X< " C/@ " C.@W " /@$ .)  " G/@] >9 3?Output: ControlsB? B"Model: Fish Population63 zATitle Page>: < Model: Management>< IModel: Fishing GearB> ?# Model: Political WillB? -I Model: gear efficiencyFC nG Model: effect on ecosystemb` D. <Century GothicFish Population Biomass*( h#@ " R8@ " ;@4 " @ " @pM 62 cnL8 spawning " @W@q@b *( Zi* " Y"@_@b *( b " [+@c %@Ru@"@/*( T " _@ @  *( YX" " a@ @ FD a constant recruitment optionB> 89" Feedback on additions>9 0" Spawning Season?B> 9# constant recruitment?>9 L'! Mean Biomass Age cP^h!@h'@*( ^ k;@E*( |e! m'@% %a9*( fe-  *( <T(  *( ,]4  ro@(po@qo@ ->L\l~$/:@F`ipw  H7L)NK w@  to effect of fishing on ecosystem>9 u?Output: ControlsB? xB"Model: Fish Population63 n56"Title Page>: ux< Model: Management>< ~IModel: Fishing GearFB v?# Model: Management MandateB? ~I Model: gear efficiencyFC }<G Model: effect on ecosystemB> 0" Feedback on additions  *( Oh#@  3 "  @ "  @ *( |? "  @@ *( ,CZKK@"  @d *( U *( <{oQ " + n *( =r *( Y# @ @,fa \3 to population : growth/recruitment additions to biomass"  @A  ) )*( A\ *( ;5??@"  @ @@" @b @X3" @7 zw 0<ArialEffects of biomass on Growth and 'Recruitment' g{,Arial(recruitment = biomass of young fish entering the fished population)*( M*@@@*( s%\ *@k*@" )*@1  (.9?O`n~  '.6<BITZ`fq| H7L  no5 ,%h:@`*( P@ @E*( ,$ 1@>9 P?Output: ControlsB? SkB"Model: Fish Population63 T6BTitle Page>: Pc< Model: Management>< YIModel: Fishing GearFB R?# Model: Management MandateB? YI Model: gear efficiencyFC X'G Model: effect on ecosystemB> l0" Feedback on additions>9 )m0" Spawning Season?.* -P|0,Spawning_period63 ]`QG main model [q<  \vP: 0 Qd 0" 9( 0p d 0"*( G)( @\@SQ@*( |~.? *( ltD @p.  S&@w&*( o\\@)@%&# v;O444,,Graph~ v <ArialThis page for setting seasonal spawning -- if desired lM?2-&@#@j$@r LL?1@f-1@V*( v^ 4@v*( |~O: 6@OD Anu|/@N^nH7L  FF Some recent research has indicated that above some minimum stock size, the number of recruits produced is effected primarily by the environment and not by the spawning stock size. FX1 Consequentially the option is presented here to allow additions due to recruitment to be a constant affected only by a noise input.  ?] %N*( PP *( 5~v" @*( | @*( 0L  @+@t*( |!<  @ F5 Even with this scenario the currently selected stock recruit relationship is in effect below the cutoff stock size. A_<ArialOptional Selection of Constant Recruitment above a Selected Population Size>9 O?Output: ControlsB? B"Model: Fish Population63 6"Title Page>: < Model: Management>< IModel: Fishing GearFB ?# Model: Management MandateB? HI Model: gear efficiencyFC G Model: effect on ecosystemB> K9" Feedback on additions>9 0" Spawning Season?B> %9# constant recruitment?*( ^ @j `0 Note that it is most sensible to use this option when also using random fluctuations in recruitment. *<L_js~  +6<ENY`iry!1BP`p $*;Pi}H7LB? G5 price and desired cpue>; b9 to management viewFA ^: changing gear efficiency>; b: to Fish PopulationJE jS, Fishing Capacity Utilization*( i6 " 1- *( |X *( P: *( 0{   5 dw 0"*( L M(@ *( 0   ,d 0"*( < E(@ "  $+ @qh@*( S#@ *( NY@ " !- "  !+ R@*( L/P@ " Q+ @*( L$=@ *( 9@ I@Y" @ " + A<@*( E  | SK!" !+ A" ! +g  7*( |L!  4?-" %+Q  x ," &+1 *(  2 *@*( b,$ ,@ P" + Ma*( l Z " /1@  \ J," 1+ V*( |i4 3$@*( " " 5+ d" $- K>9 ?;?Output: ControlsB? BB"Model: Fish Population63 7j6"Title Page>: ?< Model: Management>< IIModel: Fishing GearB> @?# Model: Political WillB? I0I Model: gear efficiencyFC HqG Model: effect on ecosystem~| _!<ArialFlow of Fishing Vessels Into and Out of the Fishery*( L  *( < c  , UAC@5BC@<{*( \'H FQ@y63  Cap. util. <)JI@*( |:* KI@/B= +" price & desired cpueRN hUU balanced fishery - vessel replacementb_ dd more vessels decrease cpue decreasing entering vesselsNK TLL very low cpue increases retirments <P*( p[ *(    <K" T+e RT@" Q&+l@ " T&+ ST@ @ *17>GPYdju~ 1@ITZsH7L*( h 9 *( LL *(  F  | .@] c" @VH "  +v " +| *( QQ@ @KK*( 3?P "  += >9 ?Output: ControlsB? bB"Model: Fish Population63 6"Title Page>: Y< Model: Management>< IModel: Fishing GearFB ?# Model: Management MandateB? I Model: gear efficiencyFC G Model: effect on ecosystemvt ?wProportion of Currently Permitted Fishing Gear that is Actually Being Used B= X6 Capacity utilization:8 n R2 to fishing gear" -MB *( C&  @b] CJUU - decreasing cpue will decrease capacity utilizationB= _5 price & desired cpue #*5@KV]fou~%6HVenw &/Z!,28H7L>:8 ,]a fish population*( -4  |0#*( FI3 *( Z *( c?! *( WD-  lWO" +` " - @N" @$ " - *( ,T " + *( \< @ |e7!*( WII @>l>9 ?Output: ControlsB? `B"Model: Fish Population63 &CTitle Page>: e< Model: Management>< IModel: Fishing GearFB ?# Model: Management MandateB? I Model: gear efficiencyFC 'G Model: effect on ecosystem63 K Cap. util.:5 /d6 fishing gear" -Lu " ? B= ?3" price & desired cpueNK <0, Output & Control: Effects of Price*( " *( \ZH #$@$$@%*( ,SM '$@ZX sNN lower income will lower minimum acceptable cpue <4$#*@" *+  0(" *-+@ $-@"" -+@' *( lQ" " 1@ 0 Note: There seem to be two issues here. Lower incomes will neccessitate continuing to fish at lower cpue to make ends meet. >8 But lower prices would require a higher catch to compensate thus raising the minimum acceptable cpue to stay in the fishery.*( 0   0\O 9Y" 96DY  0Y! ;(9@:@!:@5:@@H[vr %.#<ArialRelationship of Catch, Prices, and Income K.;**( K>G BA@9 >F* 7; *( H *( $^-  ED@FE@|GE@e *1<GNW`gnw '0;DOXc/=M]nH7L7FC f/to numbers of fishing gear:6 n6to main model t?*( /L) *( \ K-  0 "  i "  d  0" l J(" + | *( ]$ "  -  B# L BS;" +@y " -r  , YJ" - *( < " @+   F" +" + ! " +  $B" + "  +r" -[" +@X *( VfK " +@ *( O " !@q *( 9 " #+| *( | %; .9, ArialNot included: Costs of implemented improvements and the effect of these costs on acceptable cpue ratio."  8i As cpue ratio drops fishers tend to implement strategies that improve the effectiveness of their gear. These improvements tend to be absorbed into what becomes normal gear efficiency. There is also the possibility of a baseline improvement rate. u)<ArialImprovements to Fishing Gear Efficiency are Dependent on Recent Changes in Catch per Fishing Unit" @_ >9 ~?Output: ControlsB? B"Model: Fish Population63 6"Title Page>: < Model: Management>< =IModel: Fishing GearB> 7?# Model: Political WillB? wI Model: gear efficiencyFC G Model: effect on ecosystem*( < :n " 2+P *( @@@ 4@E%@ Z Two types of improvements to fishing gear and are indicated here. One is an improvement that takes place when catch per-unit effort drops below acceptable levels and fishermen attempt to raise the catch per-unit effort by improving fishing techniques. Some of this improvement will be retained as standard fishing practice. The second type of improvement could be a constant background improvement in fishing techniques regardless of the cpue. %,28?FMS\cju| &18AJU^sbiou!H7L3B> y< go to Fish Population*( c5  0Qx ydy 0y " , R1( 0n  1"  d-  0" < &(*( xB+  \ zK" - "  + " + *( l )0 " -% *( L =R@ "  +u "  +-  6 The ecosystem loss rate is dependent on the number of fishing units. Note that if 1000 units fishing for one year destroy 10 percent of capacity then each unit destroys .0001 of the capacity  \" +J FD 0y< go to units of fishing gear*(  d/H"  $?"  @Qh " -  *( /< "  +Q .H&<ArialFishing activity can decrease the underlying productivity of the fishery ecosystem" @l[ >9 (@Output: ControlsB? *3B"Model: Fish Population63 *CTitle Page>: '+< Model: Management>< 0uIModel: Fishing GearFB (o?# Model: Management MandateB? 0I Model: gear efficiencyFC /G Model: effect on ecosystem @fd N The underlying "Schaefer model" employs the concept of carrying capacity K and this provides a convenient element in the model where the effects of fishing on the environment can be incorporated. It is well known that certain fishing techniques can alter the underlying capacity of the ecosystem to support fishes. @ Herein the exact nature of that effect is not specified. It is merely implemented in a way whereby each fishing unit causes small fractional damage to the supporting ecosystem in addition to its direct effect on the fish population. ~m^ IMPORTANTLY, the affect of ecosystem degradation in this model does not have much effect even when the stock size is large. This is because the role of K is limited to the effect on mortality and becomes greater as the stock size increases. In the case of overfishing, when the stock size is small, a decreased K has only a very limited effect ~E This would indicate that there needs to be some other mechanism in the model whereby ecosystem capacity affects the fish stock. This could be a more direct effect, a negative effect, on the growth coefficient as the ecosystem declines. 1Q-0 @J 0@=*( H  |5U(34@04 @o*( \;IEE 74@-4 @u0@M>9 ?Output: ControlsB? pB"Model: Fish Population63 %6"Title Page>: g< Model: Management>< IModel: Fishing GearB> ?# Model: Political WillB? I Model: gear efficiencyFC +G Model: effect on ecosystem4 ,=N`p{  )2;DOXcnw(fqx~#,2=CJS\e#)6<BH7L N ( Use a value of 1 if managers are aware of, and account for, variations in carrying capacity.B= 0nMD to ecosystem effectsB> q7 to management mandateFA t to Units of Fishing Gear>; "'ck to Fish Population*( lknq+@ *(  bJQB@  0S "  S@@ "  DS  0KS"*( Kz;(@ *( Q&@ "  +d@@ *( $< "  @ @ *( ?(@ "  -r @@ *( R@ " -@@ "  +@}@@ *( \ Sr@ *( l X " +< " + " @` " '+/*( | 8X$ " - *( Q#@ *( |CdG" 4 @ *( K " !@ *( W`# " +@t *( U " %+@ *( \@4Y3" '@w *( @H$  }3$*( C " * +j@ ( #@+`@ " +* @' v=.<Century GothicManagement Attempts to Adjust Fishing Gear Numbers to Obtain Desired Stock Size 2 Z Relative strength of management views will vary. If difference between industry's desired rate and management adjustments is high then lobbying will be stronger and will weaken management's suggestions.*( L D  , te-12@. $^!" 24@F " 4@  *( < ss:: 72@ 0 AL Note: This ratio if managers are not "aware" of decreases in unfished stock size caused by damage to the ecosystem caused by fishing.*( 0n:/ *( |? *( 6cb" " ;<+ " :<-L *( xCC@  P4" <@+@@ " @*+ A@ ?@@d*( f: D4@ |g&" %F+@ " 'F@x " F2@ )E Can this be added? : Alternate management based on desired catch rate calculated from stock size, desired stock size, units of gear and gear efficiency.>9 HOutput: ControlsB? 6B"Model: Fish Population63 BTitle Page>: 0G Model: Management>< wIModel: Fishing GearB> pG" Model: Political WillB? I Model: gear efficiencyFC G Model: effect on ecosystem" @ !F@72- .V@Mgmt@5*@&d ,f The management approach modeled here is based strictly on the management's perception of the fish stock in relation to the assumed maximum possible stock size. If the stock is in "good shape" then management will recommend more units of fishing gear. If the stock is in poor shape than management will recommend decreased fishing gear numbers. -=0 However, as modeled, managing cannot directly remove fishing units from the fishery but can only limit entry of fishing units.*( vBN Z'@d  +6ALW]ciry&4DTevH7L>; G! to fish population tl#*( *- *( < J *( L 95= *(  |G# *( , =  @k@x @O" @<  k  @f%"  @s "  @Q *( P " @  *( BB @>; ~#l  to management view" @W " @ |Yo4<ArialThe Political Will for Management is Dependent on Current Catches Compared to Historical Catch Levels>9 ?Output: ControlsB? B"Model: Fish Population63 6"Title Page>: < Model: Management>< aIModel: Fishing GearB> Z?# Model: Political WillB? I Model: gear efficiencyFC G Model: effect on ecosystem 5 This lookup may need to be made more effective..... the effect of low catches compared to large catches in the past may need to be stronger if this effect is to be used (060616)fa qbSS historically low catches will give management more powert !,2BSaq $/5;AOZ`~H7L 3 *( Y-  @*( <\(  @>9 a?Output: ControlsB? B"Model: Fish Population63 6"Title Page>: < Model: Management>< !IModel: Fishing GearFB ?# Model: Management MandateB? [I Model: gear efficiencyFC G Model: effect on ecosystem>9 '! Mean Biomass Age*( C,  0 id 0." .+( 0 dD 0n" n.(*( >J$ @_*( |G  @I @@q62 Z - 0,AGE_of_BIOMASS_Mean_TST*( lLA !@8vq [$<Century GothicCo-Flow to calculate mean age of biomass@m ^b. Remember that "age" refers to age of _biomass_ in the stock (excluding young fish that have not yet entered the stock).B= |!6 Recruitment FractionB= =( recruitment fraction'@@ &,29Dhou{&7GXH7L*( ,@" *( X'  <P+@B>@% L["*( ,== + What is the relationship between mean age of biomass and fraction of biomass due to recruitment? X @a @. @T>9 ?Output: ControlsB? [B"Model: Fish Population63 !ATitle Page>: R< Model: Management>< IModel: Fishing GearFB ?# Model: Management MandateB? I Model: gear efficiencyFC G Model: effect on ecosystemB> !Z9" Feedback on additions>9 Z0" Spawning Season?B> Z9# constant recruitment?>9 5Z'! Mean Biomass AgeB=  recruitment fractionFA C For the purposes of this model the relation between the mean age of biomass in the fraction of additions from recruitment is indicated in the lookup function. The analytical relationship between these two values is beyond the scope of this model, but it's an interesting subject.4 .GR]hs~ +6FYlBYx&BMo&1H7LC.) $ b^ b4 Century GothicAdditions from Growthb` v34 Century GothicFishery Characteristics*( pG *( ti *( qNg *( < tw *( Lrcz *( | q *( s *( L uw fc q|F4 Century GothicPopulation Characteristicsjg ,E4 Century GothicRandomizing Reproductive Inputvr 4 Century GothicAdditions from Reproduction (Recruitment)63 <Tm0,CATCH__BIOMASS__AND_CPUE*( <dK :8 Rc See NOTES belowB? +x= Model: Fish Population*( :4 >; y@ Model: Management JE {\ Output & Control: ManagementJH Z Output & Control: Fishing UnitsJF |X Output & Control: RecruitmentB? M{] Output & Control: MainJG vZ Output: CPUE, Catch vs Biomass63 6JCTitle Page*( @ *( 5 *(  2. hM  NoiseNJ V Output & Control: Gear EfficiencyRM v}Z Output & Control: Environment Effect2. Ck NOTES 0For a standard biomass dynamic (Schaefer) model set "switch to use BH recruitment", "Switch to use ALT growth", and "Switch to use BH growth" to zero.ZX V"To deactivate the fishery set "initial number of units" to zerozv c#For recruitment only (no growth component) set "fraction of additions from recruitment" to 1~z ,Effects on recruitment are operable only if "fraction of additions from recruitment" is non-zero.*( ,vUq *( lv *( U6 VS Dq#k determines the asymptote of the stock vs additions curveZW Lq#p determines the halfway point of the stock vs additions curve*( ,R *( b *( 9 *( 9 NK NZ Output & Control: Effects of Pricenj N to see additional detail, controls, and notes - click these boxes*( b  +Note that the effect of the ALT growth function requires a non-zero value for "feedbact effect on growth".fa _4ArialUse Seasonal Recruitment*(  >9 += spawning season?*(  *( , *( L? .) a je l==' Arial Rounded MT BoldFor testing, try this slider.) d  " :;@*I fb Bz% Arialsecondary characteristics*( < o *( P FA /}Y Output: Mean Biomass Age '2=HS^it -B[o}H7L>; B Management Factors63 ST 0,CATCH__BIOMASS__AND_CPUE*( ] *( <  *( |  *( y *( $ *(  *( | s& .+  0,Lobbying_on_MgmtB? = Model: Fish Population>; @ Model: Management JE `\ Output & Control: ManagementJH `Z Output & Control: Fishing UnitsJF X Output & Control: RecruitmentB? ] Output & Control: MainJG Z Output: CPUE, Catch vs Biomass63 CTitle Page2.    NoiseNJ V Output & Control: Gear EfficiencyRM Z Output & Control: Environment Effectb_ ` to see additional detail and notes - click these boxesNK Z Output & Control: Effects of Price63 4_ managementFA Y Output: Mean Biomass Age &,2@JWhx$/:EP[fq|H7L*( L L# *( < (?  , KU@u@xK63 U>@0,CHANGES_IN_FISHING_UNIT_&$ b O@2236,,Graph20 8 Q>?0,PROPOSED_ENTRY_RATES_B? .= Model: Fish Population>; [/@ Model: Management JE \ Output & Control: ManagementJH NZ Output & Control: Fishing UnitsJF oX Output & Control: RecruitmentB? 0] Output & Control: MainJG #NZ Output: CPUE, Catch vs Biomass63 6Title Page2. B  NoiseNJ oNV Output & Control: Gear EfficiencyRM #Z Output & Control: Environment Effect*( L+]h *( U *( +y *( ro *( j *( < \V *( \yF *( gv* *( Yhs# +NOTE Should acceptable cpue be based on recent cpue. What is the effect of doing this??!*(  2. j >E0,cpue_ratio_vs_enterB= -ai Model: Fishing UnitsFA Y Output: Mean Biomass Agex *=Pct ".:SH7LeB? /= Model: Fish Population>; (0@ Model: Management JE \ Output & Control: ManagementJH OZ Output & Control: Fishing UnitsJF <X Output & Control: RecruitmentB? ] Output & Control: MainJG OZ Output: CPUE, Catch vs Biomass63 CTitle Page2. D  NoiseNJ <OV Output & Control: Gear EfficiencyRM Z Output & Control: Environment EffectNK PZ Output & Control: Effects of Price63 j ;uI0,Catch_Effect_on_Price_anB? k_ price and desired cpue63 8 L"I0,Catch_and_Price_over_Tim*( ^# *( s# .) ?;wJ0,Income_vs_cpue.) b KJ0,Price_vs_Accepb_ g to see additional detail and notes - click these boxesFA Y Output: Mean Biomass AgeH  +6ARbuBMXlwH7L.+ j EXa0,BIOM_VS_RECRUITS*( a *( +- *(  *( i3  B? M= Model: Fish Population>; $N@ Model: Management JE ~2\ Output & Control: ManagementJH ~mZ Output & Control: Fishing UnitsJF 73X Output & Control: RecruitmentB? O] Output & Control: MainJG mZ Output: CPUE, Catch vs Biomass63 !6Title Page2. b  NoiseNJ 7mV Output & Control: Gear EfficiencyRM 4Z Output & Control: Environment Effect*( W-< *( lD B Note that asymtotic level of recruitment is equal to: 0.5 * r * k * Bm*(1+k) * fraction of additions from recruitment*( ,U *( <9+- NI  Random Variation in Recruitment?*( +r& JG  Alternate Recruitment FunctionJF . Use Alternate Growth Function*( D *( K4 *( NB4 B?  Use BH Growth FunctionFA 3Y Output: Mean Biomass AgeX *=PctH7LB? = Model: Fish Population>; @ Model: Management JE nt\ Output & Control: ManagementJH nZ Output & Control: Fishing UnitsJF 'uX Output & Control: RecruitmentB? ] Output & Control: MainJG Z Output: CPUE, Catch vs Biomass63 a6Title PageFA uY Output: Mean Biomass Age2.   NoiseNJ 'V Output & Control: Gear EfficiencyRM vZ Output & Control: Environment Effect2. * +.d%0,AGE_of_BIOMASS_Mean62 , /,|%0,AGE_of_BIOMASS_Mean_TST "->Nat5gH7L64 gBW-{0,BIOMASS_EFFECT_ON_VARIOUS*( a! *( <  B? @= Model: Fish Population>; @ Model: Management JE j\ Output & Control: ManagementJH Z Output & Control: Fishing UnitsJF kX Output & Control: RecruitmentB? c] Output & Control: MainJG Z Output: CPUE, Catch vs Biomass63 <Y6Title Page2. }  NoiseNJ V Output & Control: Gear EfficiencyRM lZ Output & Control: Environment Effect e Note: The 'potential gear improvement fraction' indicates the amount of gear improvement which would be possible if a 100% effort were made. Some of this improvement is implemented if catch rates drop below what is normally acceptable. JJ The second option 'background gear improvement rate' determines what fraction of the above potential will be implemented regardless of the catch rate. b]  Click here to see: Output & Control: Gear Efficiency \a,*( D,/ " @H *( { FA ElY Output: Mean Biomass Age *=Pct0H7LBB? = Model: Fish Population>; E@ Model: Management JE \ Output & Control: ManagementJH Z Output & Control: Fishing UnitsJF XX Output & Control: RecruitmentB? ] Output & Control: MainJG Z Output: CPUE, Catch vs Biomass63 6Title Page2.   NoiseNJ XV Output & Control: Gear EfficiencyRM Z Output & Control: Environment Effect*( OO *( < V( :6 R0,BIOMASS_EFFECT_ON_VARIOUS_0*( | %@ *( T 62 8 V&0,Fishing_Gear_Efficiency*( } B? w Model: Gear EfficiencyFA Y Output: Mean Biomass Age *=PctH7L*B? L= Model: Fish Population>; @ Model: Management JE (\ Output & Control: ManagementJH (Z Output & Control: Fishing UnitsJF X Output & Control: RecruitmentB? o] Output & Control: MainJG Z Output: CPUE, Catch vs Biomass63 Ho6Title Page2.   NoiseNJ V Output & Control: Gear EfficiencyRM Z Output & Control: Environment Effect*( L 0d *( l ] &# ^/508,,Graph 8<Century GothicThe effect that fishing activity (and/or natural ecosystem variation) has on the supporting ecosystemFA QY Output: Mean Biomass Age4 *18CNTZ`flrx *:M`sH7L$*( |6 *( 0S  *( y.  c*  "*( 4( *( Y@ d*A UR*( z!#  *( 97 @@ >< NpN (from Sterman 2001)*& . jdu<0,WHITE_NOISE*% VdLu<0,PINK_NOISE*'  Q>?<0,PINK_NOISE_2jg k.Arialchange to non-zero for "noise"nj ?<Arialclick here to return to main view*( \! &@4B? = Model: Fish Population>; & @ Model: Management JE \ Output & Control: ManagementJH )Z Output & Control: Fishing UnitsJF :X Output & Control: RecruitmentB?  ] Output & Control: MainJG )Z Output: CPUE, Catch vs Biomass63 6Title Page2.   NoiseNJ :)V Output & Control: Gear EfficiencyRM Z Output & Control: Environment Effect@{yjf S=Century GothicCreation of Pink Noise StreamFA Y Output: Mean Biomass Age*( Q* \\\ *( 4 H7LWW:,G?<:Đ%:0G:p GJ(<;$$,<*4 \?r<&4|00&\?H?L000&%|%|:_7\7'  h=0??>1!=]>=>02>=>I>? >?"?*?l9?8?Q?&J?e?qvk??{???bE700&,<LjKL=\G$%%l|Q/0 0-|%%|%%:]81<H*fL*n,v0 A?33s?-&?Q?V@1?@?K@>:A> A>B}D:0|:"% *+|j3tG$'%?lBD:,<0L@A:O1L%l,:X #<*b|?:j:%| *s:{h?G0@@>H?7>ԘH?U???sc?L? 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'<  l, &@ &&G$' &&G$' &&G$' &&G$' &&G$' &'@@ L H7L&Internally defined simulation time.The purpose of this model is to provide a thinking tool for those who are interested in the management of fisheries and the factors that make management of even a simple fishery complicated.Value of catch*total change in fish stock (for graphs)JSwitch to turn off the effect of the ecosystem on additions to the stockThe effect of ecological degradation on additions to the stock. This effect is additional to any effect on the biomass carrying capacity (k) of the ecosystem. That is, it is a special effect on the additions to the stock.2Fraction of ecosystem capacity still remaining6\!frac of ecosystem remaining\!effect on additionsAdditions due to recruitment if no stock vs recruitment relationship exists above a minimum stock level. Below that stock level the normal stock recruitment relationship (as currently selected) is in effect.The fraction of additions from recruitment can be estimated from the mean age of biomass in the stock. For example when the mean age is very low then most additions to the stock must come from recruitment rather than from growth of existing biomass.If used this value will determine the fraction of additions to the biomass that are from recruitment -- the addition of new biomass in the form of new fish.Switch to turn it on the use of a fixed fraction of editions from recruitment. Otherwise the fraction of editions from recruitment is determined by the mean age of biomass in the stock..\!mean age of biomass\!est frac from recrtA fraction of the maximum possible stock size above which there is recruitment affected only by environmental conditions and not by stock size.The stock size above which there is no defined relation between new fish coming into the population (recruits) and the existing stock size. Below this value stock size is the primary influence on the biomass of recruited fish.fSwitch to turn on ( =1) or off (=0) the option for constant recruitment above a certain stock size.A graphical function which takes as x the cpue ratio and produces as y the effect on gear entry into the fishery.\!cpue ratio ...... is equal to .... current cpue / acceptable cpue\!effect on vessel entry dmnl.At low cpue the replacement rate declineszFish prices are limited if they rise above this value. For example due to the availability of other similar products.^New rate of vessel entry.... including the effect of current catch per unit effort (cpue).~effect of recent income levels on required cpue\!current compared to recent past income\!effect on minimum desireable cpue^The effect that immediate relative income level has on the lower range of acceptable cpue.Result of switch for selecting the appropriate feedback from biomass to growth. 1 selects the alternate feedback, 0 selects the BH style IF it is turned on with the other switch.FA comparison of recent past income levels to current income levelNOn off switch to turn on the alternated growth function. Default = 0 - offfThe lowest catch per unit effort that is sufficient to make participation in the fishery worthwhile.6ratio of catch to catches in the very recent past.:\!ratio of catch level to recent levels\!effect on priceZSwitch to turn on the effect of income on the acceptable cpue level. Default is on (=1)vswitch to turn on (=1) and off (=0) seasonality of recruitment (addition of new fish to the stock). DEFAULT is offBIf the switch is selected then the asyptotic function is used.JOn off switch to turn on Beverton Holt type recruitment function. 1=on.JOn off switch to turn on Beverton Holt type recruitment function. 1=on:Accumulation of catch over the course of the simulation.~if switch is on then capacity utilization is determined by cpue ratio. Other wise 100% use of existing capacity is assumed.RThe normal rate of use of fishing gear and vessels.... The default is 100% or 1.fSwitch to turn on and off the effect of cpue on fishing capacity utilization. Default is on (=1).NThe recent cpue ratio which affects how much fishing capacity will be used.jThe effect that recent catch per unit effort has on the actual use of fishing vessels in the fishery.A function describing how capacity utilization of vessels and gear will change as catch per unit effort changes. \!cpue ratio\!effect on capacity utilization6Amount of biomass added to the population each year.NAdditions to the population biomass due to growth of existing fish biomassThe average rate of increase of the population (which is also the basis of the average rate of population decrease without fishing and other influences)NExpected additions to the population biomass due the the entry of new fish.Expected additions to the population biomass taking into account random influences on "recruitment" (that is, the addition of new young fish to the stock). Alternative is the constant recruitment scenario with random fluctuations. Max functions ensure recruitment, with variations, is not below zero.RThe effective rate of increase of growth additions to the population biomass.BBiomass of young fish ("recruits") entering the fish populationjThe feedback effect of increasing stock biomass on the ability of the stock to produce new recruits. As the stock size increases the effect of increasing biomass becomes less. (When these calculations are carried forward and multiplied by the rate of increase and the current biomass then the result is identical to a Beverton - Holt type recruitment curve).6This is the normal death fraction if the current fish biomass is equal to the biomass of the unfished stock. In the standard case it is the same as the rate of increase r. In the cases when there is a feedback effect of biomass on growth and/ or recruitment, then the normal death fraction is also modified.Constant determining how fast recruitment will rise toward the asyemtotic value as the fish population biomass increases. (Is equal to the fraction of virgin stock at which recruitment = 0.5*r*virgin stock).ZThe effective fractional rate of recruitment additions to the biomass of the population.VThe effect of current fish biomass on the death fraction is the ratio of the current fish biomass to the biomass of the stock of fish if no fishing takes place (normall this is the original fish stock also called the "virgin biomass"). However, herein it it the maximum biomass that could be supported by the current habitat conditions.JFraction of the current fish biomass caught by all fishing gear units.Fraction of max biomass determining the stock size which determins asemtote for recruitment (in conjunction with r and the fraction of additions from recruitment).Fish biomass being caught.FThe current biomass of catchable size fish in the fish population.*Biomass of fish dying of natural causes.*Initial biomass of the fish population*The intrinsic rate of growth in biomass.bThis is the catch obtained by each unit of fishing gear... called catch per unit effort or CPUE.>This represents a straight line of B/k (x) on Effect (y) where the point 0.5,1 is the default value (effect is one at B/k=0.5). Thus the effect is 1 at B/k=.5 and increases to 1 plus max effect as B/k declines from the .5 to zero. Effect decreases below 1 as B/k increases. MAX is used incase B exceeds k.Maximum mutiplier that will increase rate of growth increase at lower population levels and lower it at high population levels. Perhaps in the range of .1 to .5VThe time it takes for young fish to grow large enough to enter the fishable stock.zThe number of new fishing vessels proposed by management, accounting for expected replacement of retiring old vesselsThis is the weighted mean of the two proposed entry rates where weighting is based on the strength of managments view. If the industry rate is lower than the negotiated rate then the industry rate is used .... i.e. management can't force vessels to enter the fishery.The difference between industry's proposed entry rate and that of management expressed as fraction of the fishing gear currently in the fishery.This is the biomass ratio comparing the current fish biomass to the original unfished biomass. If managers are unaware of damage to fish habitat then they will continue to use this value in determining the stock status.&Changing perception of the fisheryVThe difference between the current perception of the fishery and the new perception.The effect that the size of the differences in the proposed entry rates proposed by management and industry will have on the overall effectiveness of management... if lobbying is in effect. Larger differences will increase cause lobbying to be more effective.nThe effect that the management entity's perception has on their recommendation for fishing gear numbers.>Expected time needed to make changes in fishing gear numbersA graphical function describing how ( depending on the strength of lobbying) large differences between management's and industry's desired vessel entry rate can have an effect on the strength of management. If industry's desired entry rate is very high compared to that of management and send the management mandate will be decreased. \!difference in new vessels over current number in fleet\!effect on strength of management's views.:A switch to turn the lobbying effect on or off (off=0).JThe currently held perception of the fishery by the management entity.JThe change in fishing gear numbers proposed by the management entity.bThe management entity's perception of fishery status as based on the perceived biomass ratio.BThe stock comparison (current to max possible) used by managers.A graphical function describing the relationship between the current perception of the fishery and the effect on fishing gear numbers.\!\! Perception\!effect on fishing gear numbersDefault is the second option. .. the original value of unfished biomass. If managers regularly refit the model to the fishery data then the other option is likely to be more realistic.Management views are fully implemented if this value is 1. The strength of management's MANDATE is affected by differences between fishers and management regarding fishing gear levels, and by the effect of historical catch rates.^Has values from 0 to 1. A value of one means that management's efforts are fully accepted.Multiplier changing the perceived stock ratio due to stock assessment inaccuracies or biases. Default is 1 = no effect. This was included for testing ideas.A graphical lookup function describing the relationship between biomass ratio and perception of fishery status.\!Biomass Ratio B/K\!perception of resource^The time needed for the management entity to change its perception of the fishery status.A switch to determine which measure of max biomass managers are using. The default is that they assume the actual virgin biomass is the maximum possible. The alternative (=1) assumes that managers use analysis based on current observable stock size and that their estimate of max possible stock size is closer to the actual value as influenced by fishing activity effects on the eco-system and possible variations in natural productivity.fThe recovery time becomes longer if the ecosystem capacity falls well below the maximum capacity.:Current capacity of ecosystem to support the fish stockjFractional rate at which ecosystem capacity is lost for each effective amount of fishing gear per year.Equlibrium biomass of stock if no fishing takes place... but taking into account any damage done to the ecosystem by fishing activity.A graphical function showing the relationship between the capacity ratio and the effect on recovery time.\!\! Capacity Ratio\!Effect on recovery time dmnl:The loss of ecosystem capacity to support the fishery.JMaximum ecosystem capacity in the absence of fishing (or other) damage:Amount of capacity that is still available for recovery.FRecovery of the ecosystem's ability to support the fish population.>Time needed for ecosystem to recover from existing damage.~Change in the pink noise value; Pink noise is a first order exponential smoothing delay of the white noise input.6The correlation time constant for the pink noise.&The mean of the pink noise process.The noise seed determines which sequence of realizations for the random process are used. Simulations with the same noise seed will yield the same sequence, so different simulations can be compared. Changing the see changes the realizations.BPink Noise is first-order autocorrelated noise. Pink noise provides a realistic noise input tomodels in which the next random shock depends in part on the previous shocks. The user can specify the correlation time. The mean and standard deviation are specified by the user. (based on information from Sterman 2000)6The standard deviation of the pink noise process.White noise input to the pink noise process. The user specified the mean, standard deviation, and noise seed. The white noise input is drawn from a uniform distrib ution, then scaled to yield the correct standard deviation for the pink noise.Switch to turn off the effect of cpue on gear imporvement. Normall is on (=1), and cpue will effect how much possible improvement is implemented. When turned off (=0) the effect is influenced only by the "background gear improvement rate.">improvements incorpoarated into fishing gear effectivenessFraction of possible improvements that are incorporated into fishing gear efficiency regardless of CPUE or other influences. Default is zero.Typical gear efficiency incorporating changes in the recent past. The fraction of the fish stock caught by one unit of gear in one year (other things being equal).2The time over which cpue ratios are smoothed..changing efficiency of typical fishing gear.A graphical dfunction describing the effect that changes in cpue will have on the incorporation of fishing gear improvements. \!cpue ratio\!effect on implementation of improvements DmnlAs catch per unit effort drops below some accetable level fishermen are forced to make whatever additional improvements they can to their fishing techniques. These improvements are in addition to any baseline improvements that might also affect fishing gear effectiveness.JFraction of the current fish biomass caught by each fishing gear unit.2New maximum efficiency of fishing gear possible.Efficiency of a single unit of fishing gear. This is the fraction of the fish biomass that can be caught by a single unit of fishing gear in a year.At any given time there is a technical potential for gear improvement. This is indicated as a fraction of the existing gear efficience. Thus .05 would mean that current gear efficiency could be improved by 5% if a full effort was made..recent changes to fishing gear efficiency.>The amount of possible improvement to current fishing gear.jA smooth of recent cpue (catch per unit effort) ratios comparing the desired cpue to the current cpue.rThe time needed for changes in the efficiency of fishing gear to become incorporated into normal fishing gear.JThe desired number of new vessels on the part of the fishing industry:The ratio of the current cpue to the acceptable cpue.*The physical maximum number of new vessels that can be purchased or transferred into the fishery (i.e. limited by construction or other constraints). This value is important in determining how many vessels can enter when fishing is good. This includes vessels transfering from other fisheries.Ncpue ratio perceived by fishers is a view accumulated over a period of timeFsmooth time determining replacement fishing gear entry into fishery&Net change in fishing gear numbersThe the number of years taken into account when fishers are deciding if fishing has been good enough to convince them to enter the fishery.vThe effect that different catch rates (cpue) have on the rate of vessel (fishing gear) retirement from the fishery.bThe number of fishing gear units in use adjusted by the capacity utilization (if implemented)A graphical relationship describing the effect that cpue has on vessel retirement. As cpue ratio drops below 1 the retirement rate of vessels increases\!smooth of cpue ratio\!effect on retirment of vesselsfnumber of vessels (or gear units) entering the fishery. Can be negative in extreme circumstances..Number of vessels retiring from the fishery.*The effect that the cpue ratio has on the entry of gear units into the fishery. When this ratio is 1 there is a neutral effect on vessel entry. New vessels are more likely to enter the fishery when cpue is higher than normal. When cpue is very high all available vessels will join the fishery.jThe rate at which units of fishing gear enter the fishery when the fishery is in approximate equlibrium.vThis is the approximate minimum acceptable, or minimum target, CPUE of each fishing gear unit (e.g. a fishing boat).RLife-time of vessels in the fishery (not necessarily the life of the vessel).bThe number of fishing gear units (e,g, vessels) in the fishery at the start of the simulation.6Number of vessels normally retiring from the fisheryA graphical function which takes as x the cpue ratio and produces as y the effect on gear entry into the fishery.\!cpue ratio ...... is equal to .... current cpue / acceptable cpue\!fraction of vessels which will enter dmnl2Number of units of fishing gear in the fishery." Simulation Control Paramaters&The final time for the simulation.&The initial time for the simulation..The frequency with which output is stored.&The time step for the simulation.fA switch to turn off (=0) and on (=1) the effect of historical catch levels on management's mandate.zThe effect that historical changes in fish catches will have on management. (Only in effect if switch is turned on).NA measure of catch levels (perceived by management) over the past few years.A graphical description of the relationship between recent catches compared to historical catches and the effect of this on management's mandate. \!historical catch ratio .... is .... short term / long term catch \!effect on management mandateJA measure of catch levels (perceived by management) over the long term.Jlength of time over which long term perception of catches is determinedBRatio of short-term to long term perceptions of catch levels.Jlength of time over which short term perception of catches is determinedd AL=?zD???@@8@?>@E?Go:AD??AC;EPG@@A@??=L>@ A>@???????@@@= B? @) ;5> >GNCU^ Dgp y2A ? B =< 7L  >]>>=>??*?8?&J?qvk??1!==02>I> >"?l9?Q?e??{??8q>X>>>)\?9 ?N5?cJ?E`???1x? k?W?T:@?^>s>\S>=w=L>>>???s??u<?,?L?^??x?a??T>->7??s?@>P?0?{]??j??Z=d>쾋>F>"S?1?fff?? 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Y J>J?W?f1@ A///---\\\ :GRAPH CATCH__BIOMASS__AND_CPUE :TITLE Catch, Biomass, CPUE, & Fishing Units :WIDTH 9 :HEIGHT 6 :SCALE :VAR catch C :Y-MIN 0 :Y-MAX 20000 :LINE-WIDTH 3 :SCALE :VAR Current Fish Biomass B :Y-MIN 0 :Y-MAX 100000 :LINE-WIDTH 3 :SCALE :VAR cpue :Y-MIN 0 :Y-MAX 200 :LINE-STYLE DASH :SCALE :VAR Units Of Fishing Gear E :Y-MIN 0 :Y-MAX 400 :LINE-WIDTH 3 :GRAPH WHITE_NOISE :TITLE WHITE_NOISE :X-MIN 2010 :X-MAX 2020 :SCALE :VAR White Noise :GRAPH PINK_NOISE :TITLE PINK_NOISE :X-MIN 2010 :X-MAX 2020 :SCALE :VAR Pink Noise :GRAPH PINK_NOISE_2 :TITLE PINK_NOISE_2 :X-MIN 2010 :X-MAX 2020 :SCALE :VAR Pink Noise :GRAPH CHANGES_IN_FISHING_UNIT_ :TITLE Changes in fishing unit numbers :SCALE :VAR net change in unit numbers :Y-MIN -50 :Y-MAX 50 :LINE-WIDTH 3 :VAR actually retiring from fleet :Y-MIN -50 :Y-MAX 50 :LINE-WIDTH 1 :VAR entering fleet :LINE-WIDTH 2 :GRAPH BIOM_VS_RECRUITS :TITLE Effect of Biomass on Recruit and Growth Additions :X-AXIS Current Fish Biomass B :X-DIV 12 :X-MIN 0 :X-MAX 120000 :DOTS :SCALE :VAR delayed recruitment :Y-MIN 0 :VAR growth additions :VAR additions :GRAPH XX_VESSEL_ENTRY_STUFF :TITLE XX_VESSEL_ENTRY_STUFF :SCALE :VAR normally retiring from fleet :VAR expected rate of vessel entry :TABLE TABLE_-_CATCH__BIOMASS__AND_CPUE :TITLE Catch, Biomass, CPUE, & Fishing Units :PRETTYNUM :PRINT-EVERY 1 :X-MIN 0 :X-MAX 100 :TIME-DOWN :FIRST-CELLWIDTH 30 :CELLWIDTH 14 :FONT Times New Roman|12||0-0-0 :VAR catch C :VAR Current Fish Biomass B :VAR cpue :VAR Units Of Fishing Gear E :GRAPH PROPOSED_ENTRY_RATES_ :TITLE Proposed entry rates :SCALE :VAR managements proposed vessel entry rate :Y-MIN 0 :LINE-WIDTH 2 :VAR industry's desired entry rate :LINE-WIDTH 2 :VAR actual vessel entry rate :LINE-WIDTH 4 :GRAPH BIOMASS_EFFECT_ON_VARIOUS :TITLE Relation of Stock Biomass to CPUE, Catch and Units of Fishing Gear :X-AXIS Current Fish Biomass B :X-MIN 0 :X-MAX 100000 :WIDTH 9 :HEIGHT 6 :DOTS :SCALE :VAR cpue :Y-MIN 0 :SCALE :VAR catch c :Y-MIN 0 :SCALE :VAR Units Of Fishing Gear E :GRAPH Lobbying_on_Mgmt :TITLE Lobbying Effect on Strength of Management :Y-DIV 15 :SCALE :VAR ratio of vessel entry difference to fleet size :Y-MIN 0 :Y-MAX 1.5 :LINE-WIDTH 1 :VAR realized strength of management views :LINE-WIDTH 3 :VAR STRENGTH OF MANAGEMENT MANDATE :LINE-WIDTH 1 :VAR effect of historical catch level on management mandate :LINE-WIDTH 1 :GRAPH Fishing_Gear_Efficiency :TITLE Fishing Gear Efficiency :SCALE :VAR Typical Recent Fishing Gear Efficiency :VAR modified gear efficiency :GRAPH BIOMASS_EFFECT_ON_VARIOUS_0 :TITLE Relation of Stock Biomass to CPUE, Catch and Units of Fishing Gear :X-AXIS Current Fish Biomass B :Y-DIV 4 :X-MIN 0 :X-MAX 100000 :SCALE :VAR cpue :UNITS t/y*u :Y-MIN 0 :SCALE :VAR catch c :UNITS t/y :Y-MIN 0 :SCALE :VAR Units Of Fishing Gear E :UNITS u :GRAPH Additions :TITLE Additions :STACK-FILL 0 :SCALE :VAR delayed recruitment :VAR growth additions :GRAPH Additions/biomass :TITLE Additions vs Stock Biomass :X-AXIS Current Fish Biomass B :X-MIN 0 :SCALE :VAR recruit additions :VAR growth additions :VAR additions :VAR delayed recruitment :GRAPH Additions_B/k :TITLE Additions vs Biomass Ratio :X-AXIS ratio of current biomass to unfished biomass :X-MIN 0 :X-MAX 1 :SCALE :VAR recruit additions :VAR growth additions :VAR additions :VAR delayed recruitment :GRAPH Feedback_effect_of_bioma :TITLE Feedback effect of biomass on recruitment :X-AXIS Current Fish Biomass B :X-MIN 0 :X-MAX 120000 :SCALE :VAR feedback effect of biomass on recruitment rate :Y-MIN 0 :LINE-WIDTH 3 :GRAPH Spawning_period :TITLE Spawning period :X-MIN 2030 :X-MAX 2040 :STACK-FILL 0 :SCALE :VAR spawning period :GRAPH Seasonal_Recruitment :TITLE Seasonal Recruitment :X-MIN 30 :X-MAX 40 :SCALE :VAR pre recruits :VAR pre recruits :DATASET *2 :GRAPH Equilibrium_Ages_of__Bio :TITLE Equilibrium Ages of _Biomass_ in the Stock :Y-DIV 10 :SCALE :VAR est typical old 99 :Y-MIN 0 :VAR est typical old 95 :VAR est typical mean age :VAR mean age of biomass in the stock :VAR age of oldest 95pct :VAR age of oldest 99pct :GRAPH Catch_Effect_on_Price_an :TITLE Catch Effect on Price :X-AXIS catch C :X-LABEL Catch (t) :SCALE :VAR selling price of fish :GRAPH Price_vs_Accep :TITLE Fish Price vs Acceptable CPUE :X-AXIS selling price of fish :SCALE :VAR income adjusted acceptable cpue :GRAPH Catch_and_Price_over_Tim :TITLE Catch and Price over Time :SCALE :VAR catch C :SCALE :VAR selling price of fish :GRAPH Income_vs_cpue :TITLE Income vs Acceptable cpue :X-AXIS current income per unit :SCALE :VAR income adjusted acceptable cpue :GRAPH Income_R_vs_cpue :TITLE Income Ratio Effect on Acceptable cpue :X-AXIS recent income ratio :SCALE :VAR income adjusted acceptable cpue :GRAPH cpue_ratio_vs_enter :TITLE CPUE Ratio vs Entering Fleet :X-AXIS cpue ratio :SCALE :VAR entering fleet :GRAPH BIOM_VS_RECR_SEA :TITLE Effect of Biomass on Recruit and Growth Additions - SEASONAL :X-AXIS Current Fish Biomass B :X-DIV 12 :X-MIN 0 :X-MAX 120000 :DOTS :SCALE :VAR season corrected delayed recruitment :Y-MIN 0 :VAR growth additions :VAR additions :GRAPH AGE_of_BIOMASS :TITLE Age of Biomass in the Stock :SCALE :VAR age of oldest 99pct :Y-MIN 0 :VAR age of oldest 95pct :VAR mean age of biomass in the stock :GRAPH AGE_of_BIOMASS_Mean :TITLE Mean Age of Biomass in the Stock :SCALE :VAR mean age of biomass in the stock :Y-MIN 0 :LINE-WIDTH 3 :SCALE :VAR Current Fish Biomass B :Y-MIN 0 :LINE-WIDTH 3 :SCALE :VAR catch C :Y-MIN 0 :VAR deaths :Y-MIN 0 :VAR delayed recruitment :Y-MIN 0 :LINE-WIDTH 2 :VAR growth additions :LINE-WIDTH 2 :GRAPH AGE_of_BIOMASS_Mean_TST :TITLE Mean Age of Biomass in the Stock :WIDTH 9 :HEIGHT 6 :SCALE :VAR mean age of biomass in the stock :Y-MIN 0 :Y-MAX 8 :LINE-WIDTH 3 :SCALE :VAR fraction of additions from recruitment :Y-MIN 0 :GRAPH Ef_Biom_Rate_of_Inc :TITLE Effect of Biomass on Rate of Increase, Additions, Deaths and Net Additions :X-AXIS Current Fish Biomass B :X-MIN 0 :X-MAX 100000 :WIDTH 9 :HEIGHT 6 :SCALE :VAR additions :Y-MIN 0 :LINE-WIDTH 3 :VAR deaths :Y-MIN 0 :LINE-WIDTH 3 :VAR catch :Y-MIN 0 :LINE-WIDTH 3 :SCALE :VAR modified rate of g increase :Y-MIN 0 :LINE-WIDTH 3 :SCALE :VAR net growth of fish stock :GRAPH Biom_vs_Rate_of_Inc_etc :TITLE Effect of Biomass on Rate of Increase, Additions, Deaths and Net Additions :X-AXIS Current Fish Biomass B :X-MIN 0 :X-MAX 100000 :WIDTH 9 :HEIGHT 6 :SCALE :VAR growth additions :Y-MIN 0 :LINE-WIDTH 3 :VAR recruit additions :Y-MIN 0 :LINE-WIDTH 3 :VAR deaths :Y-MIN 0 :LINE-WIDTH 3 :VAR additions :Y-MIN 0 :LINE-WIDTH 3 :SCALE :VAR modified rate of rec increase :LINE-WIDTH 3 :SCALE :VAR net growth of fish stock :LINE-WIDTH 3 :GRAPH Changes_in_Ecosystem_Cap :TITLE Changes in Ecosystem Capacity Caused by Fishing :Y-DIV 5 :WIDTH 9 :HEIGHT 6 :NO-LEGEND 1 :SCALE :VAR Ecosystem Capacity for Biomass of Unfished Stock :Y-MIN 50000 :Y-MAX 100000 :SCALE :VAR effect of ecosystem degradation on additions :Y-MIN 0.5 :Y-MAX 1 :L<%^E!@ 1:xxx.vdf 9:xxx 23:0 15:0,0,0,0,0,0 19:90,0 27:2, 34:0, 4:Time 5:cpue ratio 24:2000 25:2100 26:2100