Broadbill swordfish: status of established fisheries and lessons for developing fisheries     

P. Ward  J.M. Porter  & S. Elscot 《Fish and Fisheries》2000,1(4):317-336

Guidelines for the assessment and management of developing swordfish fisheries are derived through an examination of five swordfish fisheries. As they develop, swordfish fisheries may be inclined to local depletion around underwater features, such as seamounts and banks. Few nations have applied the precautionary approach in managing their developing swordfish fisheries. Without controls, swordfish fisheries expand geographically and fishing effort increases, often overshooting optimum levels. However, it is difficult to distinguish clear evidence of fishery collapse; modern longliners harvest widely distributed tuna and swordfish and they are able to relocate to distant areas or switch between target species in response to fluctuations in species abundance and price. Furthermore, the wide distribution of swordfish combined with year‐round spawning and high growth rates amongst juveniles probably contribute to the apparent resilience of swordfish stocks to intensive harvesting. Over half the world’s swordfish catch is taken as an incidental catch of longliners fishing for tuna. In several areas, such as the North Atlantic, catch quotas have sometimes caused tuna longline fishers to discard swordfish. Minimum size limits have also resulted in discarding of swordfish in tuna fisheries and in dedicated swordfish fisheries. In addition to weakening the effectiveness of those management measures, bycatch and discarding add to the complexities of managing swordfish fisheries and to uncertainties in assessing the stocks. Longliners that target swordfish often fish at high latitudes where interactions with marine wildlife, such as seabird, are generally more frequent than at low latitudes. Concern over incidental catches of marine wildlife and other species is becoming a driving force in the management of several swordfish fisheries. Fishery management organisations will need to implement management measures to protect non‐target species and gather reliable data and information on the situation by placing observers on boats fishing for swordfish.  相似文献   

Covariation in shape and foraging behaviour in lateral plate morphs in the three‐spined stickleback     

O. Bjærke  K. Østbye  H. M. Lampe  L. A. Vøllestad 《Ecology of Freshwater Fish》2010,19(2):249-256

Bjærke O, Østbye K, Lampe HM, Vøllestad LA. Covariation in shape and foraging behaviour in lateral plate morphs in the three‐spined stickleback. Ecology of Freshwater Fish 2010: 19: 249–256. © 2010 John Wiley & Sons A/S Abstract – In three‐spined stickleback (Gasterosteus aculeatus) colonisation of freshwater has led to rapid evolution in various morphological and behavioural traits. Examples are reduction in lateral plate number and increased benthic foraging. These changes are believed to result from natural selection, but the evolutionary mechanisms driving behavioural changes and how such changes are associated with phenotypes, are poorly understood. Here, we study three different lateral plate morphs from a brackish water lake and one morph from a river upstream. We investigate if the lateral plate morphs differ in overall body shape and then experimentally test how foraging behaviour differ among morphs and with body shape. Foraging behaviour is measured as the consumption efficiency of benthic and pelagic prey types. The results show that lateral plate morphs differ in overall body shape and that body shape significantly co‐varies with foraging behaviour.  相似文献   

Composition of piscine prey in the diet of large pelagic fish in the eastern tropical Pacific Ocean   总被引：1，自引：1，他引：1  

Masato Moteki  Masumi Arai  Kotaro Tsuchiya  Hiroaki Okamoto 《Fisheries Science》2001,67(6):1063-1074

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A direct multiplex loop-mediated isothermal amplification method to detect three CITES-listed shark species     

Tzu-Chun Lin  Wanchien Victoria Hsiao  Shang-Jung Han  Shoou-Jeng Joung  Jen-Chieh Shiao 《水产资源保护:海洋与淡水生态系统》2021,31(8):2193-2203

1. Species identification of sharks under catch or trade regulations is important for law enforcement and species conservation. Rapid detection of Convention on the International Trade in Endangered Species (CITES)-listed species is needed for on-site screening.
2. Species-specific primers were designed to target three mitochondrial genes (ND2, COI, and CytB) in both the simplex and multiplex loop-mediated isothermal amplification (LAMP) assay for the pelagic thresher shark (Alopias pelagicus), the bigeye thresher shark (Alopias superciliosus), and the scalloped hammerhead shark (Sphyrna lewini), respectively. Another primer set designed to target S. lewini was used for detection-limit testing of the LAMP assay.
3. The refined direct multiplex LAMP was used to detect the three CITES-listed shark species and omitted the lengthy DNA extraction process. A homogenizer was used to release the DNA from the shark tissues, and a simplex or multiplex LAMP reaction was conducted for 30 min in an incubator at 65°C using species-specific primer sets.
4. Positive LAMP reactions showed a colour change from pink to yellow, whereas negative reactions showed no colour change. Multiplex LAMP assays were performed using 84 samples, which successfully identified the target and non-target species and provided a fast (<1 h), simple, and reliable method to distinguish three CITES-listed shark species from the other non-target species, for either fresh or dry fin products.
5. Results of this study and the method developed will play a critical role in assisting fishery agencies and customs officials in identifying the illegal catch and trade of CITES-listed shark species.

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Forage and migration habitat of loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) sea turtles in the central North Pacific Ocean   总被引：1，自引：0，他引：1  

Jeffrey J. Polovina  George H. Balazs  Evan A. Howell  Denise M. Parker  Michael P. Seki  Peter H. Dutton 《Fisheries Oceanography》2004,13(1):36-51

Satellite telemetry from 26 loggerhead (Caretta caretta) and 10 olive ridley (Lepidochelys olivacea) sea turtles captured and released from pelagic longline fishing gear provided information on the turtles’ position and movement in the central North Pacific. These data together with environmental data from satellite remote sensing are used to describe the oceanic habitat used by these turtles. The results indicate that loggerheads travel westward, move seasonally north and south primarily through the region 28–40°N, and occupy sea surface temperatures (SST) of 15–25°C. Their dive depth distribution indicated that they spend 40% of their time at the surface and 90% of their time at depths <40 m. Loggerheads are found in association with fronts, eddies, and geostrophic currents. Specifically, the Transition Zone Chlorophyll Front (TZCF) and the southern edge of the Kuroshio Extension Current (KEC) appear to be important forage and migration habitats for loggerheads. In contrast, olive ridleys were found primarily south of loggerhead habitat in the region 8–31°N latitude, occupying warmer water with SSTs of 23–28°C. They have a deeper dive pattern than loggerheads, spending only 20% of their time at the surface and 60% shallower than 40 m. However, the three olive ridleys identified from genetics to be of western Pacific origin spent some time associated with major ocean currents, specifically the southern edge of the KEC, the North Equatorial Current (NEC), and the Equatorial Counter Current (ECC). These habitats were not used by any olive ridleys of eastern Pacific origin suggesting that olive ridleys from different populations may occupy different oceanic habitats.  相似文献   

Spatial distribution and overlap between ichthyoplankton and pelagic fish and squids on the southern flank of Georges Bank   总被引：3，自引：0，他引：3  

Lance P. Garrison  William Michaels  Jason S. Link  Michael J. Fogarty 《Fisheries Oceanography》2002,11(5):267-285

We conducted larval and adult fish surveys on the southern flank of Georges Bank during the spring of two years (1990 and 1995) with contrasting physical conditions. We employed canonical correspondence analysis (CCA) to examine the relationships between physical variables and the spatial distribution of pelagic fish and ichthyoplankton. Surface temperature bottom temperature, and vertical stratification were significant factors affecting larval fish distributions, and there were groups of species with similar responses to these variables. There were also consistent relationships between physical variables and pelagic fish and squid abundances and spatial distributions. Pelagic fish and ichthyoplankton with similar responses to hydrographic variables had high spatial overlap, and variation in hydrographic regimes modulated the strength of this interaction. Pelagic fish and squids are potentially important predators of both larval and juvenile fish on Georges Bank. Hydrographic structure modulates the degree of spatial overlap and therefore likely influences the strength of predator–prey interactions.  相似文献   

厄尔尼诺现象对闽南-台湾浅滩渔场灯光围网渔业影响的研究   总被引：2，自引：0，他引：2  

颜尤明 《福建水产》2006,(4):11-16

本文通过对1993-2003年的Nino3、Nino3.4区的海水表层温度(SST)和闽南-台湾浅滩渔场灯光围网作业的中上层鱼类年总产量和年平均单位产量,进行线性回归分析并经F检验,得出它们在α=0.05的水平上回归效果显著的结论(F＞Fα=0.05).其中,Nino3的海水表层温度与闽南-台湾浅滩渔场灯光围网作业中上层鱼类年总产量的相关关系R=0.7225,Nino3.4区的海水表层温度与闽南-台湾浅滩渔场灯光围网作业中上层鱼类年总产量的相关关系R=0.6685;Nino3的海水表层温度与闽南-台湾浅滩渔场灯光围网作业中上层鱼类年平均单位产量的相关关系R=0.6319,Nino3.4区的海水表层温度与闽南-台湾浅滩渔场灯光围网作业中上层鱼类年平均单位产量的相关关系R=0.6541.这种关系的找出,今后可以通过美国国家海洋和大气局(NOAA)提前一年预测的NINO区海表温度数据,为闽南-台湾浅滩渔场灯光围网作业渔情预报建立简便可靠的新方法.  相似文献   

黄海北部仿刺参浮游幼体发生与附着习性的初步研究   总被引：3，自引：0，他引：3  

周玮  王志松  王军 《大连水产学院学报》2001,16(3):228-232

于1997－1998年对黄海北部大长山岛自然海区仿刺参（Apostichopus japonicus）浮游幼体的发生与习性进行了研究。用浮游生物拖网在海上定期、定点进行刺参浮游幼体调查，发现浮游幼体出现时间为7月15日－9月31日，幼体高峰出现时间为8月1日，最大资源生物量为70只／m^3。通过检查不同水层刺参浮游幼体的附苗效果，发现3m水层的附苗量最多。另外，通过海上试验和室内试验还对刺参幼体对附着基材料的选择性进行了试验。结果表明，在常用的几种采苗附着基中，幼体对棕绳、聚乙烯网片选择性最好，其次为锚流网衣和波纹板，对贝壳和胶带选择性最差。  相似文献   

闽南、台湾浅滩渔场中上层鱼类资源监测   总被引：4，自引：1，他引：4  

汪伟洋  张壮丽 《海洋渔业》1997,19(3):113-117

本文根据闽南、台浅渔场1987～1995年间灯围渔业逐年各月生产统计资料,以及渔获物组成、生殖群体结构和幼鱼发生量对中上层鱼类进行监测和研究。结果表明,80年代末期以来,福建闽南地区灯围作业船组不断减少,但平均单产逐年上升,从而保持了渔业质量在下降中相对稳定。中上层鱼类种群结构非常稳定,蓝圆鲹和金色小沙丁鱼一直是最重要的渔获对象,占灯围产量约2/3。其生殖群体几乎是一成不变,该两个鱼种叉长优势组均为180～200mm,各占60～80％,1龄鱼补充群体数量雄厚,且其幼鱼发生量连年增长,闽中、闽东沿海小型灯围和夏缯等作业夏汛产量逐年迅速上升,由此认为,90年代以来,闽南、台浅渔场中上层鱼类资源利用不足,建议扶持灯围作业,加大对中上层鱼类资源的开发力度。  相似文献   

New branch line weighting regimes to reduce the risk of seabird mortality in pelagic longline fisheries without affecting fish catch     

Graham Robertson  Steven G. Candy  Steve Hall 《水产资源保护:海洋与淡水生态系统》2013,23(6):885-900