比較三種泛線性模式標準化大西洋大目鮪族群豐度指標之適合度

Comparison of standardized abundance index of bigeye tuna (Thunnus obesus) in the Atlantic Ocean by three general linear models

羅壬廷(Jen-Ting Lo)

指導教授 ： 許建宗

國立臺灣大學/理學院/海洋研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.02057

摘要

大西洋大目鮪為大洋性中表層水域的高度迴游性熱帶鮪類，廣泛分佈於全球熱帶及亞熱帶水域，為全球性經濟魚種，其大西洋主要分佈範圍在北緯50度到南緯45度之間。台灣以鮪延繩釣在大西洋熱帶海域捕獲大目鮪，年產量自1970年攀升到8,500公噸，其後20年持續緩慢的下降。在1991年，產量突然攀升到13,850公噸，而且持續增加，一直到1996年達到高峰，總產量達21,850公噸。1998年之後因受漁獲限額年總產量16,500公噸所限，產量維持在此一限額上下波動。雖然受到漁獲限制，總大西洋大目鮪產量還是呈上升趨勢。此系群資源量逐年下滑是可以假設的趨勢。為有效達成資源狀態評估的目的，臺灣的標準化單位努力漁獲量和其它生物參數是重要的指標之一。緣以單位努力漁獲量容易受到環境因子及人為因子的影響，在引用到資源評估之前，必須先加以標準化。因此，本文利用三種最常使用在單位努力漁獲量標準化之泛線性模式、泛線性混合模式及泛線性加成模式來進行台灣鮪延繩釣在大西洋捕獲大目鮪之單位努力漁獲量標準化。再利用四種不同的統計值(AIC、AICC、BIC、cAIC)選擇最適合模式。結果顯示，經套適三種模式及檢視四種統計值後，所估得的時間序列標準化單位努力漁獲量，以泛線性加成模式為最適合標準化此一序列之模式。估得之大西洋大目鮪系群單位努力漁獲量呈現自1982年起逐年下降趨勢，在全部時序列中，1992年至1996年間有較高的水準，和在1998年為歷年來最低水準，後呈上升趨勢至2002年，再度下降。大致推斷，如所假設，本系群處在歷年來較低的資源水準。唯臺灣鮪延繩釣漁業時序列資源指標顯示，在受到嚴重漁獲努力量和高度的漁獲量下，有多年度的標準化單位努力漁獲量無法匹配，應該再予檢討。

關鍵字

大目鮪 ； 泛線性模式 ； 泛線性混合模式 ； 泛線性加成模式 ； AIC ； AICC ； BIC ； cAIC

並列摘要

The bigeye tuna （Thunnus obesus） is worldwide in tropical and subtropical waters of the Atlantic, Indian and Pacific oceans. It is distributed from 50 degree north to 45 degree south in Atlantic oceans, and Taiwanese fishery catch bigeye tunas which used longline in its tropical waters. The volume of catch rose to 8,500 t. in 1970, followed by a slow decline for 20 years. In 1991, the volume soared to 13,850 t., and reached the peak in 1996 (21,850 t.). After 1998, the volume is close to the restriction on an annual catch of 16,500 t. Though limited, the overall catches volume is still rising constantly. It is estimated that the resource of this species is going to dwindle by year. To effectively evaluate the resource status, the research has adopted important indicators, such as standardized catch per unit effort and other biomass index. However, fishing effort is easily affected by human and environmental factors. So the research will attempt to standardize fishing effort before adopting any resource assessment data. Thus, the research adopts three general types of statistic program: General linear model, General linear mixed model and General additive model, followed by utilizing several information criterions which were widely used as a criterion of model selection in fish population dynamics to determine the optimal method to standardize. The results of three different models have shown the same pattern, starting from 1982, the population of Atlantic bigeye tuna is gradually decreasing by year. The level was high during 1992 to 1996, and dropped to bottom in 1998. The level rose till 2002, then dropped again. If as presumed, the species is at the lowest level among all years. However, under heavy fishing effort and high catches, time series catch per unit effort by Taiwanese longline fishery still shows mismatch in standardized catch per unit effort. The indicator should be reevaluated.

並列關鍵字

Atlantic Bigeye tuna ； GLM ； GLMM ； GAM ； AIC ； AICC ； BIC ； cAIC

參考文獻

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