2009年葫芦岛附近海域鱼卵仔稚鱼种类组成与数量分布     

赵静  张秀梅  卞晓东  吴忠鑫  高天翔  张沛东 《中国海洋大学学报(自然科学版)》2011,41(11):34-42

2009年5、8、10和12月,利用浅水Ⅰ型浮游生物水平和垂直拖网对葫芦岛海域鱼卵、仔稚鱼种类组成与数量分布进行了4个季度的调查。调查结果表明:4个季度共采到鱼卵44粒,仔稚鱼79尾,共鉴定出13个种,隶属于6目10科11属,其中有2种舌鳎类的鱼卵未能鉴定到种。优势种为赤鼻棱鳀(Thrissa kammalensis)、沙氏下鱵鱼(Hyporhamphus sajo-ri)、绯(Callionymus beniteguri)。春季垂直拖网采集到5粒鱼卵、8尾仔稚鱼。鱼卵、仔稚鱼的出现频率分别为25%和33.33%,平均密度分别为24.272和38.835ind/100m3;夏季水平和垂直拖网分别采集31粒鱼卵、47尾仔稚鱼和5粒鱼卵、24尾仔稚鱼,鱼卵、仔稚鱼的出现频率分别为100%、66.67%和20%、73.33%,平均密度分别为4.463、6.767ind/100m2和17.934、86.083ind/100m3;秋季和冬季都仅在水平拖网采到鱼卵,出现频率分别为10%和25%,密度分别为0.259和0.324ind/100m2。分析结果表明:随着季节的变化,暖水种、暖温种、冷温种间出现交替。春、秋、冬季鱼卵、仔稚鱼群落Margalef丰富度指数(D)、Shannon-Wiener多样性指数(H′)和Pielou均匀度指数(J′)平均值均较低,且各值均低于夏季,说明夏季种类结构相对其余3季稳定,多样性指数高、种类组成复杂、种间分布较均匀。本研究结果与该海域1998年同期(5、8月)调查结果在数量分布上有明显差异,鱼卵、仔稚鱼的种类组成与数量分布发生了显著变化。  相似文献   

Comparative reproductive biology of two southwestern Atlantic populations of the hermit crab Pagurus exilis (Crustacea: Anomura: Paguridae)     

Mariana Terossi  Lucas S. Torati  Ivana Miranda  Marcelo A. Scelzo  Fernando L. Mantelatto 《Marine Ecology》2010,31(4):584-591

Pagurus exilis (Benedict, 1892) is an endemic South Atlantic hermit crab with a distribution ranging from Rio de Janeiro State, Brazil, to Buenos Aires Province, Argentina. The present study analyzed the reproduction of two populations at the extremes of this geographical distribution, and compared their reproductive period, fecundity, and changes in egg size and egg volume during the incubation period in order to assess the variability over this latitudinal range. Hermit crabs were collected monthly over a 2‐year period. In total, 108 females were analyzed for Brazil (44 non‐ovigerous and 64 ovigerous), and 141 for Argentina (87 non‐ovigerous and 54 ovigerous). Reproduction in Brazil occurs year‐round, with peaks in the fall and winter seasons; in Argentina reproduction occurs only in spring and summer. The Brazilian ovigerous females were significantly larger than the Argentina ones (Brazil: SL = 5.33 ± 1.45 mm; Argentina: SL = 4.15 ± 0.52 mm; P < 0.001). The fecundity was 1447 ± 831 eggs (317 to 2885) in Brazil and 987 ± 711 eggs (114 to 2665) in Argentina, with a trend towards higher fecundity in Brazil. Eggs in the Argentina population were larger than those in Brazil for all the three stages investigated, and no changes in egg volume were found during egg development for both populations. The reproductive traits of the two populations showed some important differences, which may reflect adaptations to local environmental conditions, demonstrating a high plasticity of reproductive features of the species in Brazilian and Argentine waters. The strategy adopted by the Argentina population involves a lower production of larger eggs compared to the population in Brazil; this lower production is associated with reproduction in cold‐water regions.  相似文献   

Aspects of the reproductive biology of skates (Chondrichthyes: Rajiformes: Rajoidei) from southern Africa     

Ebert  David A.; Compagno  Leonard J. V.; Cowley  Paul D. 《ICES Journal of Marine Science》2008,65(1):81-102

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福建太姥山晶洞碱长花岗岩地貌特征   总被引：2，自引：0，他引：2  

梁诗经  文斐成 《福建地质》2010,29(4):334-346

太姥山是东南沿海低山丘陵唯一的花岗岩峰丛-石蛋地貌,燕山晚期"A"型晶洞碱长花岗岩是太姥山造景岩石,北东东、北北西向断裂、裂隙及节理是控制山峰形态和规模的主要构造,风化剥蚀、降水侵蚀和重力崩塌是地貌形成的主要外动力作用,目前该地貌演化处于壮年早期阶段。其构造位置特殊、成景岩性独特,地貌类型丰富,是东南沿海晶洞花岗岩山岳地貌的典型代表和宝贵的地质遗迹。  相似文献   

Fecundity of chinook salmon (Oncorhynchus tshawytscha) from the Waitaki and Rakaia Rivers,New Zealand     

Thomas P. Quinn  Simon Bloomberg 《新西兰海洋与淡水研究杂志》2013,47(3-4):429-434

The fecundity of chinook salmon (Oncorhynchus tshawytscha) was estimated from maturing fish captured by anglers in the lower Waitaki River in 1985 and 1987–89, and from mature fish spawned at the Glenariffe Research Station on the Rakaia River in 1992. Fecundity was positively correlated with fork length (FL); estimated fecundities at 750 mm FL were 5024 eggs for Waitaki and 4829 eggs for Glenariffe salmon. The slopes of the regressions of fecundity on FL differed between the populations but the Glenariffe data did not differ from Rakaia River samples from 1967, 1973, and 1976. Significant inter‐annual variation in the FL‐fecundity relationship was detected in Waitaki River samples. Egg weights, taken from the Glenariffe samples, were positively correlated with length and averaged 0.17 g. However, salmon with high fecundity for their FL tended to have small eggs, and vice versa.  相似文献   

Small‐scale spatial variation in growth,size at maturity,and yield‐ and egg‐per‐recruit relations in the New Zealand abalone Haliotis iris     

Paul E. McShane  J. Reyn. Naylor 《新西兰海洋与淡水研究杂志》2013,47(4):603-612

Tag‐recapture studies revealed differences in the growth rate of Haliotis iris between headlands and bays separated by as little as 200 m. Individuals off headlands had a significantly higher incremental growth and reached a higher maximum size than those in bays. These results were consistent with observations of the size composition of H. iris which showed that few individuals of harvestable size (> 125 mm shell length) were found in bays. Differences in the growth rate of H. iris may account for the apparent differences in the size at onset of maturity: individuals off headlands, and from a fast‐growing population off Wellington, reached reproductive maturity at a smaller size compared with those in bays. Yield‐per‐recruit modelling showed greater yields from headlands than bays, but egg‐per‐recruit modelling revealed more egg production was conserved in bays than off headlands. Yields could be increased from bays by decreasing the minimum size to 110 mm. Egg‐ and yield‐per‐recruit models were sensitive to the natural mortality rate (M = 0.03, 0.05 and 0.10 compared). The results show that parameters important in the management of commercial fisheries for abalone can vary over small distances: such variation should be incorporated in management strategies for abalone fisheries.  相似文献   

Impact of minimum legal size increases on egg‐per‐recruit production,size structure,and ovigerous females in the American lobster (Homarus americanus) population off the Magdalen Islands (Quebec,Canada): A case study     

Louise Gendron 《新西兰海洋与淡水研究杂志》2013,47(3):661-674

In the mid 1990s, American lobster (Homarus americanus) from Canadian waters was considered overfished based on estimated levels of egg‐per‐recruit production (EPR). In 1997, the Department of Fisheries Oceans responded by adopting a goal of doubling the level of EPR from its 1996 level. In the Magdalen Islands (Quebec), results from a simulation model indicated that doubling EPR could be reached by increasing the minimum legal size (MLS) from 76 mm to 83 mm carapace length. This was done at a pace of 1 mm per year from 1997 to 2003. Following the increase of MLS, the size structure, mean size, and the abundance of ovigerous females improved significantly in the catches. However, levels of fishing effort are still very high. This could cause undesirable effects such as altering sex ratios and size structure of males, which could lead to sperm limitation, and reducing the contribution of multiple spawners to egg production, which could become an issue if egg quality is important. Consideration of these issues leads to the recommendation of a multidimensional approach to lobster conservation.  相似文献   

Trap‐based indicators of egg production following increases in minimum legal size in Homarus americanus fisheries     

M. John Tremblay  Marc Lanteigne 《新西兰海洋与淡水研究杂志》2013,47(3):775-783

Minimum legal size (MLS) is an important conservation measure in trap fisheries for Homarus americanus. MLS has increased in several management areas in the Canadian Maritimes since 1987. A key conservation objective has been to increase egg production, with predictions of the effects of MLS increase based on egg‐per‐recruit models. We evaluated whether expectations of increases in ovigerous females (OF) were realised when MLS was increased. Data were examined from at‐sea samples of the commercial trap catch from 11 ports from 1986 to 2003. OF indicators were developed based on the OF catch‐per‐unit‐effort (CPUE) of different sizes, and on the percentage (PCT) of females that were ovigerous. Because there were within‐season increases in CPUE and PCT, annual indicators were based on regressions of CPUE on day in the season. There was considerable variability in all the time series of OF annual indicators and any effects of smaller MLS increases could not be detected. Increases in OF indicators were evident in areas that undertook the largest MLS increases (6–6.5 mm CL).  相似文献   

Protecting window‐size female American lobster,Homarus americanus,to increase egg production     

Robert MacMillan  Michel Comeau  Manon Mallet 《新西兰海洋与淡水研究杂志》2013,47(1):525-536

A new conservation measure aimed at protecting the larger broodstock (females with a carapace length between 115 and 129 mm, i.e., window‐size females, WSF) to enhance egg production was implemented in 2003 for the American lobster (Homarus americanus) fishery in the southern Gulf of St. Lawrence, Canada. To assess the effectiveness of this new measure, a tagging project was carried out between 2004 and 2007 in the Hillsborough Bay area with the collaboration of local harvesters. Based on a single mark‐recapture Petersen model, the estimated catch rates of WSF not carrying eggs under the abdomen in the study area varied between 40% and 53%. The catch‐per‐unit‐effort (animals per 100 traps) of both berried (egg‐bearing) and non‐berried WSF increased from 0.2 to 0.8 and 1.0 to 1.6, respectively, between 2004 and 2007. Based on the estimated number of non‐berried WSF in the population observed during the spring fishery between 2004 and 2007, the potential total egg production for WSF was estimated at 1.1 billion in the study area. From this total, 515 million eggs would have been produced by WSF directly protected by the conservation measure, i.e., females that would have been harvested if not for the new regulation. Finally, the contribution of berried WSF to the annual egg production in the study area increased from 4% to 23% between 2003 and 2007 based on the at‐sea sampling programme and the fecundity curve. WSF that represented 10% of the total berried female population in 2007 contributed 23% of the annual egg production. Hence, the protection of WSF seems to be an effective conservation measure to increase egg production based on the catch‐per‐unit‐effort and egg production.  相似文献   

Observations of temperatures in some Rotorua district lakes     

J. Irwin 《新西兰海洋与淡水研究杂志》2013,47(4):591-605

A preliminary study has been made of temperatures in some of the lakes of the Rotorua district, in the North Island of New Zealand. Seasonal and diurnal variations are discussed. Two main thermal structure types are present. One, in which stratification is irregular or absent, is present in lakes that are relatively shallow and large in area, and the other, in which there is thermal Stratification from early summer to early winter, is present in lakes that are comparatively deep and large in area or else of medium depth and size.  相似文献