东南太平洋公海水域智利竹鱼探捕及其商业开发前景探讨

报道了2000年4月以来我国大型拖网渔船在东南太平洋智利专属经济区外公海水域连续4年的探捕结果,以及2003年以后商业开发的基本情况,并对商业开发前景进行了探讨。并指出,探捕区域气象、海况条件良好,能常年作业;竹鱼资源状况稳定,可进行持续开发;从2003年以来,参与开发的中国渔船已进入盈利状态,今后还有一定的增产潜力。但现有渔船设备条件较差,成为进一步提高效益的“瓶颈”。文章最后指出,中国大洋性远洋渔业的持续发展,应兼顾国际渔业合作和国际渔业竞争的方针。     

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.     

Linking Northeast Pacific recruitment synchrony to environmental variability

We investigated the hypothesis that synchronous recruitment is due to a shared susceptibility to environmental processes using stock–recruitment residuals for 52 marine fish stocks within three Northeast Pacific large marine ecosystems: the Eastern Bering Sea and Aleutian Islands, Gulf of Alaska, and California Current. There was moderate coherence in exceptionally strong and weak year‐classes and correlations across stocks. Based on evidence of synchrony from these analyses, we used Bayesian hierarchical models to relate recruitment to environmental covariates for groups of stocks that may be similarly influenced by environmental processes based on their life histories. There were consistent relationships among stocks to the covariates, especially within the Gulf of Alaska and California Current. The best Gulf of Alaska model included Northeast Pacific sea surface height as a predictor of recruitment, and was particularly strong for stocks dependent on cross‐shelf transport during the larval phase for recruitment. In the California Current the best‐fit model included San Francisco coastal sea level height as a predictor, with higher recruitment for many stocks corresponding to anomalously high sea level the year before spawning and low sea level the year of spawning. The best Eastern Bering Sea and Aleutian Islands model included several environmental variables as covariates and there was some consistent response across stocks to these variables. Future research may be able to utilize these across‐stock environmental influences, in conjunction with an understanding of ecological processes important across early life history stages, to improve identification of environmental drivers of recruitment.     

Dual effects of reversed winter–spring temperatures on year‐to‐year variation in the recruitment of chub mackerel (Scomber japonicus)

To clarify the effects of temperature on the recruitment of chub mackerel (Scomber japonicus) in the North Pacific, we investigated the influence of winter surface temperature (WST) on spawners at the time of maturity around the spawning grounds and the influence of ambient spring temperature on larvae using estimated temperature (ET) obtained from particle tracking experiments. We found a significant positive correlation between ET approximately 10 days following hatching and the recruitment per spawning stock biomass (RPS) after 2000. The closer (more meandering) the Kuroshio Current (KC) axis was in relation to the spawning ground, the higher (lower) the spring surface temperature and the higher (lower) RPS was in the spawning ground. In contrast, WST inside KC near the maturity/spawning ground was significantly negatively correlated with RPS. A significant negative correlation between the temperatures in winter and spring was detected in the area after 2000, when the conditions of the Pacific decadal oscillation index and the stability of the Kuroshio Extension were synchronous, indicating that KC shifted northward during this time. The reversed temperature pattern was consistent with the winter–spring movement of KC axis in the offshore direction and was correlated with the winter–spring difference in the intensity of the Aleutian low. These results suggest that the annual variation in chub mackerel recruitment after 2000 was strongly affected by the combined effects of ambient temperature because of the reversal of conditions that occurred between winter and spring around the maturity/spawning ground, which was related to the KC path.     

太平洋牡蛎单体苗种生产及养殖技术的研究

本项研究采用先固着后脱基或肾上腺素（ＥＰＩ）诱导方法生产太平洋牡蛎（Ｃｒａｓｓｏｓｔｒｅａｇｉｇａｓ Ｔｈｕｎｂｅｒｇ）单体苗种获成功。选用价格低廉的聚丙烯扁条包装带作为固着基，待牡蛎苗生长至０．５ｃｍ以上时，来回弯曲进行剥离，可容易获得单体牡蛎。１９９２年在１２０ｍ＾３水体中获得平均壳高０．５ｃｍ单体牡蛎４０３６．７万粒，单位水体出苗量３３．６４万粒；使用肾上腺素诱导太平洋牡蛎眼点幼虫，最佳诱导     

不同方法制备的三倍体长牡蛎养殖效果的比较

比较了细胞松弛素B(CB)和6-二甲基氨基嘌呤(6-DMAP)通过抑制受精卵极体释放的方法批量诱导三倍体长牡蛎的养殖效果.长牡蛎卵子在25℃的海水中受精,20～30min后,开始用浓度为0.5mg@L-1的CB处理,持续18～22min,受精卵处理密度为4.0～4.5×107个@L-1,三倍体产率为65.2%～70.1%,面盘幼虫孵化率为12.3%～14.5%,诱导效率指数为0.09.6-DMAP的使用浓度为400～420μmol@L-1,受精卵处理密度为3.0～3.5×107个@L-1,授精水温、处理起始和持续时间等与CB方法相同,三倍体产率为58.7%～65.4%,面盘幼虫孵化率为52.1%～55.4%,诱导效率指数为0.32.两种方法的采苗率基本相同,采苗器为基质较硬的栉孔扇贝贝壳.海区养殖采用浮筏夹苗吊养技术,两种方法诱导的三倍体牡蛎养殖性状没有明显差别.通过比较CB和6-DMAP两种诱导方法及三倍体的养殖效果表明,后者具有更好的应用性.     

On-farm evaluation of three different hatchery sources of Pacific white shrimp (Litopenaeus vannamei) cultured in on-levee tanks in low-salinity waters of west Alabama

ABSTRACT

Shrimp farmers in Alabama who produce the Pacific white shrimp, Litopenaeus vannamei, have recently reported abnormally low survival at harvest. Farmers have hypothesized that this phenomenon may be due to disease, toxic algae, shrimp source, or reduced shrimp robustness in later stages of production. To compare performance of shrimp from different sources, postlarvae were obtained from three different hatcheries and stocked on the same day in on-levee tank systems (TS) on two farms (Farm 1-TS; Farm 2-TS1; Farm 2-TS2). Following 104 days of culture on Farm 2-TS1 and Farm 2-TS2, there were no differences in survival (72.8%–91.2%) or final weight (19.8–24.6 g). At Farm 1-TS following 107 days of culture, there were differences in survival from shrimp sourced from one hatchery (40.5%) compared to the other two hatcheries (61.0%–69.8%). Results demonstrated acceptable growth performance and survival from all hatchery sources.     

Effect of culture system on the nutrition and growth performance of Pacific white shrimp Litopenaeus vannamei (Boone) fed different diets

Two 8-week feeding trials were conducted with juvenile Pacific white shrimp, Litopenaeus vannamei (Boone) to compare the growth and performance of animals fed a series of experimental and commercial pelleted shrimp and fish feeds and dietary feeding regimes within an indoor running-water culture system and an outdoor zero-water-exchange culture system. The best overall shrimp growth performance was observed for animals fed the experimental shrimp diet and all-day feeding regime under outdoor zero-water-exchange culture conditions. Final body weight and average weekly growth rate under these conditions were 2.8 and 3.4 times greater, respectively, than animals of similar size fed with the same diet under indoor running-water culture conditions. Although direct comparison between indoor and outdoor culture systems is difficult because of the lower indoor water temperatures, and consequently lower mean daily feed intake of animals, it is believed that the higher growth and feed performance of animals reared under outdoor `green-water' culture conditions was primarily due to their ability to obtain additional nutrients from food organisms endogenously produced within the zero-water-exchange culture system. The most promising features of zero-water-exchange culture systems are that they offer increased biosecurity, reduced feed costs and water use for the farmer, and by doing so provide a potential avenue of moving the shrimp culture industry along a path of greater sustainability and environmental compatibility.