Short-term stress and mortality of juvenile school prawns, Metapenaeus macleayi, discarded from seines and trawls     

M. K. BROADHURST  S. S. UHLMANN 《Fisheries Management and Ecology》2007,14(5):353-363

Abstract  Two experiments were carried out to assess the short-term impacts to juvenile school prawns, Metapenaeus macleayi (Haswell) discarded from commercial seining and trawling in New South Wales, Australia, and the potential utility of modifications to operational and/or onboard handling practices designed to improve survival. For both gears, discards were handled according to two general categories of treatment (termed mild and extreme) chosen to represent the plausible limits of severity during existing commercial operations. A total of 600 trawled and 480 seined school prawns (from both treatments), along with appropriate numbers of controls (previously collected and housed in acclimation tanks), were placed into cages (in groups of 10). Subsets of each of these groups were then destructively sampled over periods of up to 5 days and examined for their mortality and physiological response (measured as levels of l -lactate in the haemolymph). In both experiments, the temporal mortalities in the treatment groups ranged between 0% and 15% and, for the most part, were not significantly different to controls. Prawns in the treatment groups had similar, significantly elevated levels of l -lactate approximately 40 min after being caught, but these returned to levels approaching baseline estimates within 48 h. Under the conditions examined, juvenile school prawns appear capable of withstanding a range of stressors associated with being discarded from active gears, and their fate is not greatly influenced by the duration of gear deployment and subsequent air exposure. However, further work is required to quantify other sources of unaccounted fishing mortality and, ultimately, the impacts that discarding has on stocks.  相似文献   

Migration of kawakawa Euthynnus affinis in the waters near Taiwan     

Wann-Duen  CHIOU  Liang-Kang  LEE 《Fisheries Science》2004,70(5):746-757

ABSTRACT:   Kawakawa Euthynnus affinis is the most abundant species among the small tuna in the coastal waters of Taiwan. The migration pattern of kawakawa to Taiwan was determined in the present study based on the species' feeding habits and reproductive biology and on temporal variation of catch for kawakawa and its prey fishes. Schools of this species successively migrate to Taiwan from September to May, and then move away in June. They travel to the waters off Taiwan with the warm Kuroshio current, migrate toward coastal waters for feeding and move away for spawning. It is suggested in the present study that the kawakawa spawning ground is in the waters of the northern Philippines. The migration of kawakawa exhibits size-segregating behavior. Schools of immature young fish first arrive in the coastal waters around Taiwan, followed by the adults.  相似文献   

慈竹制造Lyocell纤维可行性研究   总被引：1，自引：0，他引：1  

许炯  蒋应梯 《浙江林业科技》2005,25(4):18-20,23

通过研究慈竹的纤维素含量,尤其是研究和测试了影响纤维素分子量等各种因素,认为以慈竹为原料,制造Lyocell纤维是可行的,并用慈竹浆成功地纺制出了竹Lyocell纤维样品.  相似文献   

重庆缙云山慈竹种群年龄的初步研究   总被引：7，自引：0，他引：7  

苏智先 《竹子研究汇刊》1990,9(2):47-55

慈竹(Neosinocalamus affinis)系四川分布面积最大和用途最广的合轴型竹种。作者在重庆缙云山慈竹种群年龄研究过程中,发现慈竹种群之无性系个体的年龄与其个体生物量和各器官生物量相关密切,其器官数量也呈显著相关;慈竹秆的形态学特征与其个体的年龄,地下茎和地上茎(秆)的分枝级数与其年龄均呈直线相关。地下茎分枝级数(RSB_x)与其年龄(A_(rs))的回归模型:A_(rs)=(RSB_x_(max) 1)-RSB_x,相关系数Υ_(rs)=-1.0000,O_(x-1)=0;秆分枝级数(CB_x)与其年龄(A_c)之相关模型为A_c=CB_x,相关系数Υ_c=1.0000(一年生个体除外),O_(x-1)=0。  相似文献   

城市废水暴露对食蚊鱼肝脏EROD酶活性的影响   总被引：1，自引：1，他引：0  

陈文娟  谢勇平  张晓婵  赖静萍  金子越  方战强  方展强 《天津农业科学》2014,(2):54-59

采用动力学酶标荧光法,检测了东莞市数所污水处理厂、制药厂和电子厂废水对食蚊鱼(Gambusia affinis)肝组织中7-ethoxyresorufin o-deethylase(EROD)酶活性的影响,评价了运用EROD酶活性监测水环境污染物的生物效应的可行性。结果显示,食蚊鱼分别暴露于经稀释为20%,40%,60%,80%不同梯度的废水液72 h后,肝脏EROD酶的活性分别与受试城市污水处理厂、制药厂和电子厂的废水之间存在剂量效应关系,EROD酶活性随污水浓度的增加而提高。电子厂废水的最大诱导倍数与对照组的比值可达到5.26,这表明其水体中存在的有机污染物较多,污水处理厂次之,制药厂的出水中污染物最少。研究表明,食蚊鱼肝组织EROD酶活性可以作为监测城市废水污染的理想生物标记物,后续的研究工作应使之标准化。  相似文献   

桁杆虾拖网捕捞脊腹褐虾网囊网目选择性试验   总被引：3，自引：3，他引：0  

徐宝生  陈雪忠  汤振明  黄洪亮  郁岳峰  张勋  冯春雷 《海洋渔业》2008,30(3)

采用套网试验法在长江口渔场对25 mm桁杆虾拖网网囊网目的选择性进行了试验。结果表明:当网囊网目内径为25 mm时,网囊与套网内脊腹褐虾的体长范围在30~80 mm之间,其中网囊内虾的优势体长在46~70 mm之间,套网内虾的优势体长在41~60 mm之间;50%选择体长L0.5为50.53 mm,选择范围SR为9.86 mm;逃逸虾的平均存活率为96.25%。  相似文献   

沙栖新对虾繁殖和幼体发育的初步研究     

纪成林  黄瑞 《上海海洋大学学报》1996,(3):170-176

沙栖新对虾Ｍｅｔａｐｅｎａｅｕｓ ｍａｏｙｅｂｉ ｋｉｓｈｉｎｏｕｙｅ广泛分布于印度－西太平洋地区，我国分布于福建、台湾、广东、海南和广西沿海，为我国东南沿海常见虾类之一，一般体长５５－９０毫米，其中雄性以６０－６５毫米、雌性以７０－８５毫米的体长出现频率最高，该虾群体中性成熟比例随体长增加而增大，在繁殖季节内体长在８０毫米以上的个体性腺多已成熟。沙栖新个体虽小，但生长发育很快，对环境的适应，尤其  相似文献   

食蚊鱼对水生昆虫的捕食选择性研究     

刘丽娟  童晓立 《华南农业大学学报》2012,33(1):44-47

为了解食蚊鱼Gambusia affinis对华南地区水生昆虫多样性的影响,在实验室条件下,以食蚊鱼栖境中有代表性的3种水生昆虫为猎物,研究食蚊鱼的捕食选择性.结果表明,在单捕食者-多种猎物作用系统中,当猎物密度较低时,食蚊鱼对不同猎物的捕食选择性差异不显著.但随猎物密度的增加,食蚊鱼对白纹伊蚊Aedes albopictus幼虫和蛹的捕食量明显增加,对摇蚊Chironomus kiiensis幼虫和蜉蝣Cloeon bengalense稚虫的捕食量下降.在单捕食者-2种猎物的作用系统中,在猎物比例相同的情况下,食蚊鱼更喜欢捕食白纹伊蚊幼虫;但是在猎物总数不变的情况下,改变猎物比例,对食蚊鱼总的捕食量影响不大.说明食蚊鱼喜欢捕食漂浮于水面上、会动的活体猎物,对死的或不动的猎物不敏感,且对蚊子幼虫具有明显的嗜好性.  相似文献   

料慈竹施肥制度的研究   总被引：4，自引：0，他引：4  

吴炳生  张家贤 《竹子研究汇刊》1998,17(3):21-28

1993—1997年在赤水市复兴镇对新造料慈竹进行施肥试验研究。采用正交设计和定株（丛）观测与标准竹解析的方法,以竿材产量为指标,应用数理统计分析尿素 过磷酸钙 氯化钾的混合用量与配比;合理的施肥时期与方法。为科学合理的施肥提供依据。  相似文献   

料慈竹种群结构与产量的研究   总被引：3，自引：0，他引：3  

吴炳生  张家贤 《竹子研究汇刊》1998,17(4):13-18

本文以料慈竹的竹丛生长变化为研究对象,在相同林分内按设计设置固定样丛,试验期间逐年结构调整。每年调查新竹生长量并号竹,进而统计分析。结果表明,竹丛内保留1～3年生竹的新竹产量高,竹丛内各龄竹株百分率基本相近的新竹产量大,采伐强度以每年各龄竹按20％～40％采伐为宜;丛间密度以每亩42～74丛为好,丛内立竹密度以保留26～35株／丛则有利于产量的提高。  相似文献