美洲大赤魷(Dosidicus gigas)為大體型之外洋表層魷類，主要分布於東太平洋水域。其為東太平洋海洋生態系之主要組成物種之一，於1970年代開始成為商業漁業之目標物種。 漁業壓力對美洲大赤魷族群生物量變動之影響，以及連帶之生態系效應，為漁業生態學家之關注焦點。臺灣美洲大赤魷之漁業規模雖然不大，但此漁業可為阿根廷魷添加量不足時之替補，且大赤魷目前為南太平洋區域漁業管理組織之管理目標物種，對其族群動態、海洋生態及漁業管理等有必要密切觀察。本研究應用臺灣美洲大赤魷漁業資料，探討族群資源量變動趨勢及環境因子效應。 美洲大赤魷空間分布以秘魯北部近岸水域較高。 近年之體型組成皆以大體型群為主。 由GAM分析顯示，時、空間變數對大赤魷資源量變異量之解釋能力較佳，可能反映大赤魷具相當的年間變異，及高度的近岸、遠岸洄游型態。由相對資源量指標顯示，自2005年以後逐漸降減。 以Depletion方法估算大赤魷期初資源量，在2002-2012年間平均比例逃逸量為52%，高於目前建議之魷類漁業管理目標(40%)。 近年漁船之空間分布樣式與早年(2007年前)不同，可能反映大赤魷族群空間分布樣式之改變，或潛在之環境狀態改變之影響。 後續研究應考慮規畫適當之生物標本採樣，及增加可能影響大赤魷資源量環境變數之討論。
魷釣船隊之過去(1986~ )作業之水域有四，即北太平洋之溫帶水域、南太平洋的紐西蘭週邊水域、西南大西洋之阿根廷及福克蘭附近水域，以及東南太平洋之秘魯及智利外海。 目前(2012)則僅有其三，規模依序為 －－ 西南大西洋、東南太平洋及西北太平洋(主要是秋刀魚)。 魷釣船隊之作業漁場，以西南大西洋漁場為主。 以近十年(2003~2012)的漁產量分析，遠洋魷魚之平均年產量為12.8萬公噸，其中西南大西洋漁場佔80.1 %；東南太平洋漁場產量約佔18.1 %。 本(2012)參與西南大西洋作業之船數為90艘，投下7,893 d-v 之努力量，單船之卸魚量(landing)較去年增至114 % (932 t v-1 vs. 819 t v-1)，顯示本年之到岸量有一些增長。
西南大西洋之作業，其總產量之變化約有3-8年之上下波動(fluctuation)週期。 前(2010)年漁況是最近週期之谷底，只有30,543 t，卻在去(2011)年反彈上來，達到69,577 t (228 %)。 今年更加強一些，達到83,949 t，為去(2011)年的121 %。 以165,000 t y-1為均衡產量而言，本年之產量為均衡值51 %。
西南大西洋之漁場利用情形有集中之傾向。 大部分漁船作業均集中在200 m等深線之向陸一側，而很少走向中陸棚區。 本(2012)年之漁獲量最高的方格發生區域在46.5 ~ 47.5oS之間及49 ~ 49.5oS附近接近200m等深綫處(約在61oW)。 這些位置每半度空間的年漁獲量都有5,000 t以上。 由作業現場溫度顯示，45.5 ~ 46.5間之水溫偏高，約在14~15 ℃，福島北方作業於適水溫(11 ℃左右)，而東北方水域作業則較適溫稍低(9 ~ 10 ℃)。
漁獲努力量經標準化後，單船之產量(Y, kg)大體上與標準漁獲努力量(X, v-d)成正相關之關係(Y = 6,679 X + 281,407)。 Ternary plot評估船隊成員的總漁獲量、總努力量及平均日漁獲量之相對百分率可見，本(2012)年相對努力量部分稍稍偏低，但漁獲量則全體性地偏低，漁獲率則維持平均水平。 總體較去年而言，算是稍佳。 體長頻度分布顯示：本(2012)年之體型較去年為小。 最後數個雙週之體型應是亞成熟的階段，但特別發現，第十個雙週，有兩個體型峰值，其均值約在10 cm 及29 cm，後者是BNPS之餘緒，前者則是表現新的添入(Recruitment)。
將西南大西洋的漁場，依政治管轄劃分為公海，阿根廷經濟水域、福克蘭外圍保育區及福克蘭過渡保育區，加以觀察漁獲的情形，發現本2012年最主要的魷魚生產區為福克蘭外圍區，共生產58,650 t (69.9 %)；次為公海的20,892 t (24.9 %)。 與去年相較，福克蘭外圍水域在2012年有較高的比重。
||Abstract of "Studies on squid and saury fish biology and stock dynamics":
1. "Fisheries oceanography and stock assessment of Dosidicus gigas in the Southeast Pacific" :
The jumbo (or Humboldt) squid, Dosidicus gigas, is a large pelagic ommastrephid squid which distributed in the Eastern Pacific Ocean (EPO). The jumbo squid is an important component of its ecosystem in the EPO and is the main target of squid fisheries in this region. The central challenge for fisheries ecology is to understand the abundance variations of resources under fishing pressure and its synergistic effects to the ecosystems. The jumbo squid fishery in Taiwan is not dominant in context of production or values, while it could act as a substitute for Illex argentious fishery. Also, jumbo squid has been a target species of SPRFMO which enter into force on 23 September 2012. Therefore, it is essential to understand its population dynamics, environmental influences and fisheries management. This study applied fisheries data of D. gigas fishery in Taiwan to explore the variation of stock abundance and the environmental influences. The distribution of D. gigas abundance was higher in the coastal waters off northern Peru. The size composition harvested by Taiwanese fleet was identified as large-size group in recent years. The results of GAM showed the temporal and spatial variables could explain higher variation of squid abundance than other variables. This may result from highly variable features of squid populations and high migration pattern of jumbo squid. A decreasing trend of squid abundance index was found since 2005 afterward. The average annual proportional escapement in 2002~2012, which estimated by depletion method, was 52% which higher than the management target (40%) suggested in the Illex fishery. The annual spatial patterns of fishery in recent years were different from the earlier years (before 2007) which may imply a change in migration pattern for the jumbo squid, or a potential change in the environmental conditions of habitat. Designing and collecting biological data, and including more environmental variables in models may improve our understanding to variability of abundance for jumbo squid in the EPO.
2. "Assessment of Argentine squid recruitment strength, and its abundance index in relations to marine condition and annual yield in Southwest Atlantic" :
Taiwanese jigging fleet explored 4 waters in the history (1986 ~ ); i.e., temperate Northwest (NW) Pacific, South Pacific around New Zealand, Southwest (SE) Atlantic and Southeast (SE) Pacific off Peru and Chile. In 2012, the production amounts of waters ranked In general, Taiwanese jiggers sought after Argentine flying squid and supplemented by saury fish. For the squid production in the last 10 year, the fleet fished 128 thousand tons in annual average, of which 80.1 % from SE Atlantic and 18.1 from the SE Pacific. In 2012, 90 vessels took parts in SE Atlantic fishing, threw 7,893 d-v fishing efforts, and resulted in 114 % outweighed the last year’s (932 t v-1 vs. 819 t v-1), signified increased landings per vessel.
The annual production in the SE Atlantic fluctuated in a cycle of 3 – 8 years. The year of 2010 hit the floor in the last cycle having a production of 30,543 t, however it bounced back at 2011 when 69,577 t (228 %) was produced. The current year produced 83,949 t, which is 121 % of the last (2011) year. Taken production of 165,000 t y-1 to be equilibrium, current fishing is simply 51 % to the equilibrium.
The fishing sites in the SW Atlantic tended to be congregated; most jiggers located at the shelf-side of the 200 m isobaths but very few moved onto the mid-shelf. In the current (2012) year, cells with higher catches (＞ 5,000 t v-d-1) is located in 46.5 ~ 47.5oS and 49 ~ 49.5oS closed to 200-m isobaths (ca. 61 oW). However, the in situ water temperature was relative high (14 ~ 15 oC) at 45.5 ~ 46.5. The waters in the far-north of the Falkland Islands was good for fishing at a temperature of 11 oC., but the temperature in the northeast Falkland Islands was a bit lower (9 ~ 10 oC).
Fishing efforts from vessels operated in the SE Atlantic are standardized to eliminate inter-vessel bias. The amount of production per vessel (Y) was found positively related to standardized fishing effort (X): i.e., Y = 6,679 X + 281,407。 Ternary plot rated that fishing effort threw by some vessel in 2012 was relatively low, production by vessel was low in general, and catch rate was remained to the level of average; all these sums to an ordinary fishing condition in 2012. Mantle length distribution exhibited that squid was caught at smaller size as compared to 2011. It is worth to note that in the 10th fortnight two groups of squid peaked at 10 and 29 cm were found, and the former may be new cohort recruited into the fishing ground in addition to the BNPS stock. The SW Atlantic production can be broken into 4 parts according to political regions; i.e., high sea 20,892 t (24.9 %), Falkland Outer Conservative Zone (FOCZ) 58,650 t (69.9 %) ), Falkland Interim Conservative Zone (FICZ) 4,171 t (5.0 %) and Argentine EEZ 240 t (0.3%).
3. "Stock assessment of Pacific saury for application of Taiwanese saury fishery to certification of the Marine Stewardship Council" :