台湾海峡中部近海虾类数量和优势种分布特征

Shrimp density and dominant species in onshore waters of the Central Taiwan Strait

采用2009年11、2010年4月和8月台湾海峡中部近海海域3个航次的渔业资源调查资料,结合该海域水文情况,研究台湾海峡中部近海虾类在春、夏和秋季的资源密度、平面分布和优势种。结果表明:虾类资源重量密度表现为秋季(135.45 kg/km2)>春季(96.77 kg/km2)>夏季(88.02 kg/km2),尾数密度表现为夏季(34.55×103 ind/km2)>秋季(33.65×103 ind/km2)>春季(18.95×103 ind/km2)。依据相对重要性指数(IRI),该海域虾类春秋季的优势种均为哈氏仿对虾(Parapenaeopsis hardwickii)和周氏新对虾(Metapenaeus joyneri),哈氏仿对虾的IRI值分别为6 733.05和10 552.82,周氏新对虾IRI值分别为10 536.11和5 981.94,夏季优势种为须赤虾(Metapenaeopsis barbata)(IRI=6 242.29)、哈氏仿对虾(IRI=4 236.10)和细巧仿对虾(Parapenaeopsis tenella)(IRI=1 999.67)。通过贡献率β值,调查海域虾类总密度变化与主要优势种虾类密度变化密切相关,春季优势种周氏新对虾对总重量和尾数的贡献率β值分别为1.11和0.84,秋季哈氏仿对虾的贡献率β值分别为0.74和0.78,各季节虾类总密度主要与优势种密度的平面分布规律一致。这是因为该海域虾类以广温广盐性种类为主,水团对总密度分布的影响不明显。调查海域夏秋季资源密度高于附近瓯江口海域资源密度。主要的经济种类为哈氏仿对虾、鹰爪虾和中华管鞭虾,因此台湾海峡中部虾类渔场具有一定的开发利用价值。

Based on the data from three oceanographic surveys in onshore waters of the Central Taiwan Strait during autumn 2009, spring and summer 2010, shrimp density, horizontal distribution, and dominant species were studied, along with hydrological features. The biomass of shrimp was greatest in autumn （135.45 kg/km2）, followed by spring （96.77 kg/km2）, and then summer （88.02 kg/km2）. By contrast, density was greatest in summer （34.55×103 ind/km2） and autumn （33.65×103 ind/km2）, and least in spring （18.95×103 ind/km2）. The dominant species, Parapenaeopsis hard-wickii and Metapenaeus joyneri, left their winter grounds in early May and migrated to offshore waters. The higher biomass when abundance was low was a result of greater individual weight. In summer, shrimp were mainly smaller individuals that grew rapidly, resulting in an escalating abundance and declining biomass. After feeding, individuals increased in biomass and the peak in abundance primarily consisted of the new generated groups. According to the in-dex of relative significance （IRI）, Parapenaeopsis hardwickii （IRI values of 6 733.05 and 10 552.82） and Metapenaeus joyneri （IRI values of 10 536.11 and 5 981.94） were the dominant species in spring and autumn. In summer, Metape-naeopsis barbata （IRI=6 242.29）, P. hardwickii （IRI=4 236.10） and P. tenella （IRI=1 999.67） were the dominant species. Based on theβvalue, M. joyneri, the main dominant species in autumn, contributed 1.11 and 0.84 to total biomass and individual density, respectively, and Parapenaeopsis hardwickii contributed 0.74 and 0.78 in autumn. The seasonal change of shrimp density was correlated with the dominant species, which also had the same horizontal distribution. The shrimp in this area were composed mainly of eurythermal and euryhaline species which were not affected by envi-ronmental changes. The shrimp fishery in the central Taiwan Strait has development potential because of the economi-cally valuable species Parapenaeopsis hardwickii, Trachypenaeus curvirostris, and Solenocera melantho.