1、RemotelysensedspatialdynamicsoftheIllexargentinesfishery,SouthwestAtlantic西南大西洋遙測阿根廷魷漁業時空動態之研究Claire M. Waluda , Huw J. Griffiths, Paul G. RodhouseFisheries Research 91 (2008) 196-202Reporter:凌子雅AbstractIllexargentinus,theArgentineshort-finnedsquid,isanimportantspecieswithinthePatagonianshelfecosyst
2、em,whereitsupportsamajor multi-nationalfishery.Thefishingfleetoperatinginthisregioniscomprisedofjiggingvesselswhichattractsquidusingpowerfulincandescent lights.Thesefishinglightsaredetectableinremotelysensedsatelliteimagerywhichmakesthefisheryunusuallyamenabletoalarge-scaleanalysisofitsspatialdynami
3、cs.Inthispaper,long-terminter-annualvariabilityinfleetdistributionandextentisexaminedusingimageryfromtheDefence MeteorologicalSatelliteProgram-OperationalLinescanSystem(DMSP-OLS)fortheperiod1993-2005.Thefisherywasfoundtooccupyawide areaacrosstheshelfandslope,withregionsofconsistentfishingactivityobs
4、ervedonthehighseas(45-47S)andtothenorthoftheFalkland Islands(Malvinas).Distributionofthefisheryoverthe13-yearstudyperiodwasvariable,with28%ofthefishedareaoccupiedin1-2years,and7%oftheareaoccupiedin12-13years.Annualcatchlevelswerepositivelyassociatedwiththeextentoftheareaoccupiedbythefleet.Higher cat
5、chescorrespondedtothefisheryoccupyingawidelatitudinalrange,whereaslowercatcheswereobservedduring2004and2005correspondingtoacontractionofthefisheryawayfromthesouthofitsrange.Inyearsofveryhighcatches,fishingtookplacealongalmosttheentirelatitudinal rangeofthespecies.Duetotheintensityoffishing,changesin
6、thedistributionofthefleetcanreflectshiftsinthedistributionofI.argentinus;thishaspotentialforthelong-termmonitoringofthishighlyvariablesquidfishery.摘要阿根廷魷為巴塔哥尼亞陸棚生態系中重要之物種，亦為許多國家主要之漁獲魚種。在此區作業之漁船包含魷釣船，為一種利用強力白光吸引魷魚之漁業。而衛星遙測可以測得此種漁業之燈光影像，使我們可以利用此影像來大規模之分析阿根廷魷漁業之時空動態。本篇研究利用國防氣象衛星系統所測得之影像，檢視19932005 年期間，
7、魷釣船年間分布之長期變化。阿根廷魷漁業遍及巴塔哥尼亞陸棚以及斜坡區，而在公海(4547 S)以及福克蘭群島 (馬爾維納斯群島)北方之區域，每年均有此種漁業在此作業。在這13年研究期間，阿根廷魷漁業之分布是多變的，在只出現12年之 作業區域就佔了全部作業區之 28%，而1213年均有出現 之作業區域則佔了全部作業區之 7%。年間之漁獲量與漁船分布之區域範圍呈正相關。 阿根廷魷漁業高漁獲量分布之緯度範圍廣泛，但在2004與2005年期間，觀察到漁業自南部開始縮減之現象 。 在漁獲量極高之年份中，阿根廷魷漁業沿著幾乎整個魷魚分布之緯度範圍進行作業 。隨著不同之漁業捕撈強度，漁船分布之改變反映出阿根廷
8、魷分布之逐年變動，正因如此，我們有必要長期監控此種高度變動性之魷魚漁業。Fig.1.DistributionoffishinglightstargetingIllexargentinusonthePatagonian Shelf,SouthwestAtlantic,obtainedfromtheDefenceMeteorologicalSatellite Program-OperationalLinescanSystem(DMSP-OLS)fortheperiod1993-2005. Legendindicatesthenumberofyearsinwhichfishingtookplacei
9、neach2.7km gridsquare,withredareasindicatingregionsinwhichfishingoccurredinall13 yearsofthestudyperiod.Greylinesindicate200and1000mdepthcontours. Blacklinesindicateterritorialboundaries(Highseas,ArgentineanEEZ(ExclusiveEconomicZone),FICZ:FalklandIslands(150mile)InterimConservation Zone(FICZ),Falklan
10、dIslands(200mile)OuterConservationZone(FOCZ).Fig.2.Frequencyofoccupation(numberofyearsthatfishingoccurredineach gridcellbasedon27by27kmgridcells)ofthePatagonianshelfregionbytheI.argentinuslight-fishingfleet,1993-2005.Fig.3.Percentageinter-annualBray-Curtissimilarityofthegeographicdistributionoffishi
11、nglightsoftheI.argentinusfleetonthePatagonianshelf,1993-2005.Fig. 4. Inter-annual variability in the latitudinal extent of the I.argentinus fishing fleet on the Patagonian shelf (calculated as the proportion of the maximum lit area for each 27 km latitude band; n= 90). Legend shows the percentage oc
12、cupation of each latitudinal band by the fleet in each year, 1993-2005.Fig. 5. (a) Annual variability in catch (log tonnes; open circles, dashed line) and area fished (km2; closed circles, solid line) for the period 1993-2005. (b) The area occupied by the fishery (km2) vs. the total catch (log tonnes) for the corresponding year. () Regression line (R2 = 0.62); (- -) 95% confidence intervals. (Regression equation: log catch = 4.02 + 0.000159area fished (km2).
