【作者】 林龙山；

【导师】 高天翔；

【作者基本信息】 中国海洋大学 ， 渔业资源， 2009， 博士

【摘要】 20世纪50年代至今,小黄鱼渔业经历兴盛期、衰退期、严重衰退期和恢复期,近十年来,全国渔业统计产量一直维持在历史高位。但与此同时,小黄鱼渔获物个体出现小型化、低龄化和性成熟提前等现象,资源处于生长型捕捞过度状态。为研究小黄鱼如何在捕捞过度状态中仍然维持较高的资源量水平,以及如何在当前的渔业资源状态下合理利用和管理小黄鱼渔业资源,本论文利用1999年4月～2008年9月黄海南部和东海渔业资源定点调查和常规监测调查资料以及历史资料,对小黄鱼渔业现状、种群动力学、空间分布和环境特征、产卵场分布及其环境特征、繁殖生物学、摄食生物学、渔业管理策略等进行了研究。黄海南部和东海小黄鱼渔业利用现状和资源现存状况研究结果表明,小黄鱼广泛分布于黄海南部和东海海域,在588种游泳动物中其渔获重量占17.01%,渔获尾数占14.17%,均仅次于带鱼,为重要优势种,在该海域中具有重要地位。种群动力学研究结果表明,小黄鱼渔获物个体小型化、低龄化现象非常明显;生长参数逐渐增大,而渐进体长逐渐变小;产卵亲体小型化和低龄化以及性成熟提前趋势加重的现象也非常明显。空间分布和环境特征与生长相关关系研究结果表明,黄海南部和东海小黄鱼资源密度指数分布除秋季外其他三个季节均无显著差异;水温是影响两个海域小黄鱼资源分布的主要环境因子;两个海域的小黄鱼在不同生长阶段的生长条件因子均表现为明显的月份变化,尚未性成熟小黄鱼的生长条件因子差异并不显著,已达到初次性成熟小黄鱼的生长条件因子差异则较为显著;东海的生长性能指数优于黄海南部。产卵场分布及其环境特征和繁殖力研究结果表明,目前小黄鱼产卵场范围较过去有所扩大,范围已经扩展到外海海域,黄海南部和东海的主要产卵场分布区具有不同的海洋环境特征;相对繁殖力较过去有显著提高,但卵径变小。摄食习性及其营养级研究结果表明,当前小黄鱼食物组成以甲壳类为主,其次为鱼类、头足类等,优势种类为糠虾、磷虾、七星底灯鱼、脊腹褐虾和鹰爪虾等,小黄鱼的营养级为2.72级,属于第三营养级中的低级肉食性动物。与过去相关研究结果相比,小黄鱼食物组成已经发生了较大变化。渔业管理策略研究结果结果表明,当前小黄鱼渔业资源利用状况不合理,现有捕捞规格有待进一步调整;目前资源状态下其最大持续产量(MSY)为12.62×104t,总允许渔获量TACMSY为9.52×104t,TAC0.1为7.98×104t,最小可捕标准为150mm。论文最后建议采取限制相关作业类型的网具网目尺寸、规定小黄鱼最小可捕标准为150mm、限定上市鱼低于最小可捕标准的比例不得高于20%、建立相互监督机制、在主要产卵场建立禁渔区、延长伏季休渔期为6月1日～10月1日、限制捕捞努力量、规定捕捞限额指标为8.0×104t和采取经济手段来调整渔业等相关措施优化小黄鱼渔业管理。更多还原

【Abstract】 Since the 1950s, the small yellow croaker (Larimichthys polyactis) fishery in the southern Yellow Sea and the East China Sea has undergone four phases: prosperity (1950-1960), decline (1961-1976), nearly collapse (1977-1989), and recovery (1990-2008). During the recent 10 years, the nation wide catch landing of small yellow croaker has been reaching a historical peak in China. On the other hand, some distinctive phenomena in their population biology have been observed, which are characterized with individual miniaturization, low age composition and advanced first maturity.In order to elucidate the mechanism underlying the chronological development of this fishery, especially why the fishery resources could remain at a relatively high level even under heavy fishing pressure, we employ population analysis to investigate the changes of the biology and ecology of this fish in the past 50 years, which include their population dynamics, spatial and temporal distribution patterns, reproductive biology, feeding, distribution and environmental characteristics of their spawning grounds, and fishery management strategy etc. The data used for this study are obtained from the fixed-point surveys of fishery resources (Apr., Jun., Sep., Dec.) and the annual monitoring surveys (every months), in the southern Yellow Sea and the East China Sea from April 1999 to September 2008 by East China Sea Fisheries Research Institute, Chinese Academy of Fisheries Research.Results indicate that the small yellow croaker is dominant species which is widely distributed in the southern Yellow Sea and the East China Sea. The catch accounted for 17.01% in weight and 14.17% in number of 588 species of nektons, second to hairtail (Trichiurus japonicus), the No. 1 fishery catch in the sea. In the past 50 years, population changes are characterized with individual miniaturization, domination of low age groups, increases in growth parameters but decreases in approximate length and weight. The parent stocks are characterized with obvious advances in age and size at first maturation.Based on the relationship between environmental factors and fish growth, it is concluded that there are no significant differences in stock-density index between the southern Yellow Sea and the East China Sea in either season except in autumn. Water temperature is the key factor influencing the small yellow croaker resources in these areas. Its growth condition factor varied monthly with growth stages. For the immature fish, it exhibits no significant difference between theses two regions, but the difference for the mature ones is statistically significant, with growth performance index in the East China Sea being superior to that in the southern Yellow Sea.It is found in this study that the spawning grounds of the small yellow croaker have obviously expanded from nearshore in the past to offshore at present. Moreover, the major spawning grounds in the southern Yellow Sea and the East China Sea had different ocean environmental characteristics. Although the relative fecundity has obviously increased compared to the past, their yolk diameter was getting smaller.Results show that the small yellow croaker mainly feed on crustaceans, followed by fishes and cephalopods. A total of food species have been identified in their stomach contents. Among them, the dominant species are Mysidacea sp., Euphausia sp., Benthosema pterotum, Crangon affinis and Trachypenaeus curvirostris. The average trophic level of small yellow croaker is 2.72. Compared to the results of previous studies, the diet composition of small yellow croaker has undergone great changes.Population dynamics and fishery management studies indicate that the size at fishing for small yellow croaker at present is not reasonable and should be modified. At the current resources status, the maximum sustainable yield (MSY), the total allowable catch (TACMSY) and the total allowable catch (TAC0.1) of small yellow croaker in this region are estimated about 12.62×104, 9.52×104 and 7.98×104 tons, respectively. The minimum size at fishing is limited to 150 mm in body length.As for fishery management, the following measurements are suggested: The net mesh size of relevant fishery gears should be restricted. The proportion of the market fish with the size lower than 150 mm in body length should not exceed 20%. Closed fishing grounds should be established in major spawning grounds. The summer closed fishing seasons should be prolonged to June 1-- October, 1. The fishing effort should be restricted with the defined catch quota limited to 8.00×104tons. In addition, economic means should also be implemented to adapt fishery-related measures to regulate small yellow croaker fishery in the southern Yellow Sea and the East China Sea.更多还原