臺灣北部海域劍尖槍鎖管單位努力漁獲量標準化之探討

Abstract

本研究利用樣本船資料，進行劍尖槍鎖管 (Uroteuthis edulis) 單位努力漁獲量 (CPUE) 標準化，並區分在火誘網漁業中，劍尖槍鎖管漁場與鰹類漁場之不同，以更精確掌握劍尖槍鎖管資源之變動。結果顯示樣本船以鰹類為目標魚種的5至7月間，其作業地點非屬劍尖槍鎖管當時主要分布地點。鰹類之努力量排除前，劍尖槍鎖管名目CPUE之月別變化顯示每年有二個主要漁獲高峰，而排除後二個主要漁獲高峰現象消失。以泛線性模式 (GLM) 進行2009至2014年間名目CPUE之標準化，鰹類之漁獲努力量排除前，GLM依序將年別、漁區別、漁船別、月別及月別與漁區交感等因子納入模式，模式總解釋率為56.7%，其中以漁區別對CPUE的影響最大。排除鰹類之漁獲努力量後，GLM標準化分析則依序將年別、漁船別、漁區別、月別及月別與漁區交感等因子納入模式，模式總解釋率為47%，其中以漁船別對CPUE的影響最大。二種資料之標準化後CPUE年間變化趨勢相近，且均較名目CPUE平緩，其中2012年之資源豐度最低，2013年則為近6年之最高點。在計算劍尖槍鎖管CPUE時，為避免錯誤的漁獲努力量影響其CPUE之計算，區分鰹類之漁獲努力量有其必要。In this study, we used the logbook data from the sampling vessels of the torch light fishery to distinguish the fishing grounds of bonito and Uroteuthis edulis and to standardize the catch per unit effort (CPUE) of U. edulis. The results showed that the fishing grounds where the sampling vessels targeted bonito from May to July were not the main distribution locations of U. edulis at that time. The monthly nominal CPUE of U. edulis showed two peaks when the bonito fishing effort was included and one peak when the bonito fishing effort was excluded. A generalized linear model (GLM) was used to standardize the nominal CPUE from 2009 to 2014. The GLM, which included the effects of year, area, fishing vessel, and month, as well as the interaction between area and month, explained 56.7% of the variation in the CPUE when the bonito fishing effort was included. The area had the main effect on the CPUE standardization. When the bonito fishing effort was excluded, the GLM including the same effects explained 47.7% of the variation in the CPUE, but the main effect came from the fishing vessel. The standardized CPUE trends based on the two data sets were similar and smoother than the nominal CPUE. The CPUE series showed that the abundance of U. edulis was the lowest in 2012 and peaked in 2013. Because of the difference of bonito and U. edulis fishing grounds, it is necessary to distinguish bonito fishing effort when calculating the CPUE of U. edulis.