Spatio‐temporal management of fisheries to reduce by‐catch and increase fishing selectivity

Time/area closures have been widely used in fisheries management to prevent overfishing and the destruction of marine biodiversity. To a lesser degree, such spatio‐temporal management measures have been used to reduce by‐catch of finfish or protected species. However, as ecosystem‐based management approaches are employed and more fisheries are managed through multispecies, multiobjective models, the management of by‐catch will likely become increasingly important. The elimination of by‐catch has become a primary goal of the fishing policies of many countries. It is particularly relevant in the United States, as the deadline for setting annual catch limits (ACLs) in all fisheries passes in 2011. This will result in a dramatic expansion of the number of catch and by‐catch quotas. Such catch measures may result in the early closure of otherwise sustainable fisheries when by‐catch quotas are exceeded. To prevent such closures and the consequent economic hardship to fishers and the economy, it is imperative that managers be given the tools necessary to reduce by‐catch and improve fishing selectivity. Targeted spatio‐temporal fishery closures are one solution open to managers. Here, we examine how the spatio‐temporal and oceanographic characteristics of by‐catch may be used by managers to design fishery closures, and place these methods within a decision tree to assist managers to identify appropriate management measures. We argue that the current movement towards marine spatial planning (MSP) presents an important impetus to examine how we manage fisheries spatially, and we offer a first step towards the objective participation of fisheries in the MSP process.     

闽南_台湾浅滩渔场六种主要中上层鱼类的生化组成检测分析

检测了闽南－台湾浅滩渔场六种主要中上层鱼类（蓝圆鱼参、金色小沙丁鱼、鲐鱼、颌圆鱼参、竹Ｊｉａ鱼、羽鳃鲐）鱼肌的生化组成,蛋白质含量为１６．９４％～１８．７７％,脂肪含量为２０．１２％～２５．１５％。随鱼体体长的增加,脂肪含量增长。鱼肌脂肪含量与繁殖活动存在密切相关的季节变动。鱼肌中均含１７种氨基酸,必需氨基酸占总氨基酸的４２．４５％～４９．３９％,极性氨基酸占４２．８２％～４５．１６％,非极性氨基酸占３９．２４％～４１．５９％,鲜味氨基酸占４２．５６％～４６．０２％。     

远洋渔业应立足于渔轮国造

从当前渔船业的现状出发,定性定量地分析了我国应建造大型远洋拖网渔船的原因与意义。并指出建造大型拖网渔船应有政府支持,政府支持不会增加政府负担;对大型拖网渔船建造计划的实施提出一些建议。     

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

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.     

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

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.

     

Spatial distribution and overlap between ichthyoplankton and pelagic fish and squids on the southern flank of Georges Bank

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.     

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

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.     

闽南、台湾浅滩渔场单拖渔业监测调查

本文根据2005年1~11月闽南、台湾浅滩渔场单拖渔业调查监测资料,分析和研究该海区单拖渔业利用状况、主要渔获物资源动态。结果表明:2005年渔获量平均密度指数(CPUE)3月最高,达134.41kg/h,随后迅速下降,9月为全年最低,仅34.75kg/h;渔获物组成以生命周期短、个体小、营养级较低的种类为主,二长棘鲷居绝对优势,占总渔获重量的38.8%;各主要种类渔业资源时空分布变化较为明显;近十年来,渔船功率和网具的日趋大型化,小型单拖渔船数量有所减少。通过监测调查为渔业管理部门制订科学的渔业资源养护措施、加强和完善渔业管理等提供科学依据。     

明治时期以来日本远洋渔船业发展变化分析

为探索我国远洋渔船业的发展及政策制定,借鉴日本的相关经验,利用日本史料数据对日本远洋渔船业发展进行定性分析、对其结构变化进行定量分析研究。研究归纳:1)历史上两次正面的成功转型升级经验。2)20世纪70年代至今衰退期的反面教材。论证日本远洋渔船业衰退不仅受国际环境变化的外部因素影响,更有其内在原因。日本政府实施的远洋鼓励政策失去了时效性,解决包括远洋渔业在内的整个渔业产业衰退的方法至今没有找到。厘清日本远洋渔船业转型升级路径,借鉴日本经验与教训对我国远洋渔船业发展提出如下建议:1)完善远洋渔业油价补贴政策。2)提供融资便利。3)推动鱼食文化改革。4)加快远洋企业自身能力建设。