大西洋金枪鱼延绳钓主要渔获种类及其分布

根据收集的有关文献和海上调查资料，分析了大西洋金枪鱼延绳钓生产的主要渔获品种的生物学特性、捕捞生产情况及管理措施等。此外，还根据FAO建立的金枪鱼生产数据库，采用GIS软件制作了大西洋金枪鱼延绳钓主要渔获种类捕捞产量的地理空间分布图。并分析了其资源的空间分布特征。     

The changes in proximate compositions and glycogen contents in the dorsal ordinary muscles of the full-cycle cultured Pacific bluefin tuna Thunnus orientalis occurring with growth

ABSTRACT:   Using full-cycle cultured (FC) Pacific bluefin tuna (body length [BL], 42.6–66.4 cm; body weight [BW], 1.66–7.40 kg, n  = 15), the changes in chemical compositions and histological structure of the cephalal parts of the dorsal ordinary muscles (DOM) occurring with growth were investigated. A positive correlation ( r  = 0.9644, P  < 0.05) was observed between BL and BW with growth. The protein, lipid and ash contents of DOM and condition factor did not change with growth. However, the glycogen content of DOM increased ( P  < 0.05) from approximately 55 cm (BL) in this study. Using optical microscopic photographs, the various shapes of muscle fibers were observed and it was noted that the muscle fiber diameter increased ( P  < 0.05) with growth. Using transmission electron microscopic observation, many glycogen granules were observed in muscle fibers (especially, side of connective tissue) of DOM throughout the growth stage in this study. These results indicate that the glycogen content of DOM of FC Pacific bluefin tuna increases before the lipid with growth.     

应用栖息地指数对印度洋大眼金枪鱼分布模式研究

运用分位数回归方法对温度、温差、氧差与印度洋大眼金枪鱼延绳钓钓获率进行二次回归分析,找出最佳上界方程,以最佳上界方程拟合的数值来建立栖息地指数(HSI)模型,从而揭示印度洋大眼金枪鱼栖息地的分布模式。研究表明,温度、温差、氧差与印度洋大眼金枪鱼延绳钓钓获率的最佳上界分位数回归方程分别为HR_(T0.9)=-44.803 7.685T_(0.9)-0.255T_(0.9)~2,HR_(dT_(0.9))=6.234 0.953dT_(0.9)-0.026dT_(0.9)~2和HR_(dO_(0.88))=7.422 4.25dO_(0.88)-0.727dO_(0.88)~2。10°N～10°S间印度洋海域大眼金抢鱼HSI指数达到0.9以上;10°N以北的波斯湾及10°S～15°S海域的HSI指数为0.8～0.9;15°S～40°S之间海域HSI指数介于0.7～0.8,其中50°E～90°E、15°S～25°S间存在一片季节性HSI指数<0.7的区域;40°S以南的海域HSI指数<0.6。     

东南太平洋智利竹(竹夹)鱼渔业生物学的初步调查研究

根据在东南太平洋的探捕调查 ,对所渔获的智利竹鱼 (Trachurus murphyi)群体的构成、叉长与体重的关系 ,年龄与生长的关系和性腺发育等基本生物学特征进行了初步探讨。结果显示 ,渔获智利竹鱼的叉长范围为 1 45～ 61 0 mm,体重范围为 42～ 1 95 0 g,年龄组成为 2～ 1 3龄 ,3～ 4龄鱼为优势群体 ,初次性成熟年龄为 3龄 ,不同年龄个体性腺成熟的节律差异明显     

Stable isotope variations in otoliths of Pacific halibut (Hippoglossus stenolepis) and indications of the possible 1990 regime shift

Stable oxygen and carbon isotope ratios (δ¹⁸O and δ¹³C) from archived otoliths of Pacific halibut, Hippoglossus stenolepis, were measured to examine the most recent regime shifts in British Columbia and the Gulf of Alaska. δ¹⁸O values of these otoliths ranged from −1.5 to +2.8‰ VPDB, and were consistent with the life stages and migration behavior of halibut. δ¹³C varied from −3.3 to +0.9‰ VPDB, but did not show a transition from the juvenile to the adult stage as does δ¹⁸O. Evaluation of δ¹⁸O and δ¹³C values of mature halibut (ages 8–12) indicated that the 1977 regime shift might have a warming impact on the northeast Pacific fish stocks. In contrast, a possible regime shift around 1990 with a bottom seawater temperature decrease of about 2 °C might have occurred in both the areas. The connection between stable isotope variations in otoliths and the climate regime shifts is thus potentially useful in studying the population dynamics of Pacific halibut, and decadal scale (e.g., the last 20–30 years) ocean environmental changes.     

Pacific sand lance of the Port Moller estuary, southeastern Bering Sea: an estuarine^dependent early life history

Three waves of spawning Pacific sand lance (Ammo-dytes hexapterus) entered the Port Moller estuary from mid-January to late May 1990. Each wave laid its eggs on sand in lower Moller Bay with the center of egg distribution about 14 km inside the estuary. After incubation for 45 to 94 d, each cohort of eggs hatched out over a 41- to 63-d period. Larvae moved at a rate of 0.21 knvd“¹ toward a deep fjordlike basin at the head of Herendeen Bay inside the estuary about 20 km southwest of the center of hatch. The basin has the lowest flushing rate of the estuary, and unlike the rest of Port Moller, it is vertically stratified, which allows the development of a spring-summer zooplankton community with greater biomass than any other location in the estuary. Larvae may have moved to the basin to enhance growth or to avoid offshore transport to areas of low food abundance, but we cannot demonstrate a direct link between growth and habitat. We conclude that the Port Moller sand lance stock has an estuarine early life history that evolved in response to the unique physical conditions of the Port Moller estuary–a shallow, well-mixed site with sandy substrate that is suitable for incubation of demersal eggs next to a deep, vertically stratified fjord with a rich zooplankton community that is suitable for rearing of larvae.     

Considerations of stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean based on fishery data

Yellowfin stock structure in the Indian Ocean was studied by using industrial tuna longline fishery data. Three types of test variables were used to detect stock structure, i.e., CPUE, age-specific CPUE, and coefficient of variation for size. Time-series data of test variables were compiled for six sub-areas that were arranged by dividing the whole region systematically along longitude lines every 20 degrees. Then time-series data were smoothed by moving averages, and regressed by simple models. Patterns of time-series trends were graphically and statistically compared to classify homogeneous sub-area groups. Two assumptions were (a) that homogeneous stocks exist longitudinally and overlap in adjacent waters, and (b) that test variables within homogeneous sub-area groups are equally affected, and hence patterns of the time-series trends are similar. After graphical screening for significant sub-area groups, analysis of covariance was applied to test homogeneity of regression parameters representing patterns of the time-series trends. By classifying homogeneous sub-area groups, stock structures were determined at the P <0.05 and P <0.50 levels. The P<0.50 level was recognized as a useful criterion for ‘weak’ test variables since masked or vague structures at the P <0.05 level were likely cleared at this level in many cases. Results of this study and past stock structure studies were reviewed and compared. It was concluded that there are two major and two minor stocks of yellowfin tuna. The two major stocks (the western and the eastern) are located at 40^o-90^oE and 70^o-130^oE respectively. The minor stocks are the far western and the far eastern stocks (the latter possibly being a part of the Pacific stock), which are located westward of 40^oE and eastward of 110^oE respectively. Neighboring stocks are intermingled in adjacent waters.