基于耳石微化学特征的鄱阳湖刀鲚永修群体的关键栖息地识别     

肖百义  杨健  姜涛  刘洪波  陈修报 《湖泊科学》2024,36(3):870-880

随着长江禁渔国策的持续实施,长江干流和沿线通江湖泊中刀鲚资源及其关键栖息地将有可能得到恢复。为了确证长江禁渔后的2020年在鄱阳湖永修瓢头水域所采集到21尾刀鲚的洄游履历和资源类型,本研究采用电子探针微区分析技术(EPMA)对其耳石元素锶(Sr)和钙(Ca)的微化学特征进行了测定和分析。结果显示,所有个体耳石的Sr/Ca值变化较为复杂。自耳石核心至边缘Sr/Ca值分别出现了对应淡水生境的低值(<3)和对应河口半咸水或海水生境的中高值(>3),最后边缘部分再次出现了对应洄游返回淡水生境的低Sr/Ca值(<3)。Sr含量面分析图中也呈现出了对应淡水—河口半咸水—海水—淡水的蓝色—黄绿色、红色—蓝色变化的图谱;证明上述个体均具有明显的江海洄游特征,为典型溯河洄游型刀鲚。鄱阳湖永修瓢头水域是一处尚未曾正式报道过的洄游型刀鲚分布区。根据性成熟度和摄食情况可将瓢头水域刀鲚分为产卵场群体和非产卵群体两类。通过与鄱阳湖其他水域刀鲚情况的比较分析可以推定,两类刀鲚可能起源于鄱阳湖内两个不同区域的产卵场。对于产卵场群体而言,瓢头水域可能更主要起到产卵场的作用;而对于非产卵群体来说,瓢头水...  相似文献   

基于深度学习和时空特征融合的海洋渔船密度预测方法          下载免费PDF全文

丁依婷  胡志远  董帝渤 《应用海洋学学报》2024,43(2):350-359

为了从海量渔船轨迹数据中挖掘隐含的信息和知识,进而为渔业行政主管部门的决策提供科学依据,本研究以AIS渔船轨迹数据为研究对象,提出了一种基于深度学习和面向时空特征融合的海洋渔船密度预测方法：首先,利用渔船轨迹数据集对渔船行驶区域进行网格划分;其次,筛选出渔船高密度区域进行研究,避免数据稀疏性问题;再次,根据渔船轨迹数据的时空分析,构建三维时空融合矩阵;最后,通过卷积循环神经网络模型捕获渔船分布的时间和空间特征,并利用卷积神经网络的堆叠加强对空间特征的学习。实验通过东海海域渔船真实轨迹数据进行具体测试,结果表明渔船密度预测值与真实值非常接近,平均绝对误差为4×10-4,模型较好地拟合了渔船密度分布特征,有效地提高了渔船捕捞热点预测的准确性和鲁棒性。  相似文献   

Participatory artisanal fisheries management in islands: Application to the Canary Islands (Spain)     

《Marine Policy》2017

Socio-economic development of small-island fishing communities is greatly dependent on local coastal and marine resources. However, illegal fishing and aggressive practices in insular ecosystems lead to over-exploitation and environmental deterioration. Moreover, a lack of scientific data increases uncertainty and prevents the adequate monitoring of marine resources. This paper focuses on the integration of local fishing communities into decision-making processes with the aim of promoting artisanal fishing on the Island of Tenerife (the Canary Islands), as a way to preserve the marine ecosystem and socio-economic development of traditional cofradias (fishers' organisations). A qualitative methodological framework, based on participatory problem-solution trees and focus groups, was used to identify the main factors impeding the sustainable development of the artisanal fishing sector on the island and to elaborate collective proposals with policy implications. The fishing community involved identified four main issues that are maintaining an unsustainable island fishery: 1) Over-exploitation; 2) Poor self-management of cofradias and commercialisation problems; 3) Fisher individualism and low co-management strategies, and 4) Illegal fishing increase vs. artisanal fishing decline. Results show the required policy enhancements to tackle them and the need to adapt regulations to the local situation.  相似文献   

中西太平洋金枪鱼围网高产渔区年间变化及其原因分析   总被引：1，自引：1，他引：0  

戴澍蔚  陈新军  张衡  周为峰  徐良琦  肖卫平 《海洋学报》2017,39(2):120-128

金枪鱼类是中西太平洋海域重要的经济鱼种,其中鲣产量约占到总产量的50%。本研究利用1995-2010年16年的中西太平洋（20°S~20°N,120°E~155°W）鲣围网生产统计数据和Niño3.4海区（5°S~5°N,120°~170°W）海表温度异常数据,对这16年鲣产量最高的十大渔区（5°×5°）进行时空格局分析,讨论渔场分布差异及CPUE与ENSO指数的关系。结果表明:16年间十大作业渔区主要分布在5°S~5°N、130°~175°E区域,这十大渔区产量占总产量的比重达47.5%,其中5°S~0°、155°~160°E,0°~5°N、130°~135°E,0°~5°N、135°~140°E及5°S~0°、160°~165°E等4个渔区产量占高产渔区产量的比重均超过10%,是中西太平洋重要的鲣产区。高产渔区的分布受海表温度影响较大,在厄尔尼诺时期,高产渔区分布明显偏东,主要分布在155°~180°E海域;在拉尼娜时期,高产渔区分布明显偏西,主要分布在130°~160°E海域。  相似文献   

ScotMap: Participatory mapping of inshore fishing activity to inform marine spatial planning in Scotland     

《Marine Policy》2017

A detailed understanding of fishing activity in Scottish waters is required to inform marine spatial planning. Larger fishing vessels are fitted with Vessel Monitoring Systems (VMS) offering spatial information on fishing activity. VMS does not cover smaller vessels (under 15 m), which fish predominantly in inshore waters where the competition for space is often greatest. To improve knowledge of the distribution of fishing activity and value of fisheries in Scotland's inshore waters, Marine Scotland conducted a participatory fisheries mapping project, known as ScotMap. The data were collected during face-to-face interviews with 1090 fishermen of Scottish registered commercial fishing vessels under 15 m in overall length and relate to fishing activity for the period 2007–2011. Interviewees were asked to identify the areas in which they fish, estimate the contribution these areas make to vessel earnings, and to provide associated information. The majority of interviews relate to creel fishing. The data collected were aggregated to provide mapped outputs of the monetary value, relative importance to fishermen and the usage of the seas around Scotland (number of fishing vessels and number of crew). ScotMap outputs provide information on the locations of inshore fishing activities and the economic importance of different sea areas at a much higher spatial resolution than was previously possible. Outputs have informed marine policy development, provide a valuable resource for marine spatial planning in Scotland and illustrate how participatory mapping can generate useful resources on the location and importance of inshore fishing areas.  相似文献   

Experimental Investigation and Numerical Analysis to Develop Low-Energy Large-Midwater Trawls     

Jihoon LEE  Taeho KIM  Chun-Woo LEE  Subong PARK 《海洋工程》2017,(6):700-708

Fuel consumption in fisheries is a primary concern because of its effects on the environment and the costs incurred by fishermen. Many studies have been conducted to reduce the fuel consumption in fishing operations. Fuel consumption due to fishing gear during a fishing operation is generally related to the hydrodynamic resistance on the gear. This means that fuel consumption is proportional to the drag created by the towing speed. Based on numerical methods, this study suggests a new approach to reduce fuel consumption in fisheries. The results of the simulation are in good agreement with those of model experiments. The total as well as partial resistance forces on the gear are calculated by simulation. The simulation results suggest improved materials and gear structure for reducing the hydrodynamic forces on the gear while maintaining gear performance. The method for assessing the gear performance involves measuring the height and width of the net mouth. Furthermore, this study investigates the efficiency of a low-energy trawl from an economic point of view. The findings of this study will be useful in reducing greenhouse gas (GHG) emissions in fishing operations, and thereby contribute toward lowering fishing costs by saving fuel.  相似文献   

Multi-stakeholder collaboration yields valuable data for cetacean conservation in Gamba,Gabon     

G Minton  JR Kema Kema  A Todd  L Korte  PB Maganga  JR Migoungui Mouelet 《African Journal of Marine Science》2017,39(4):423-433

Private industry, the Government of Gabon and two international NGOs collaborated to conduct marine surveys off the coast of Gabon, Central Africa. Surveys addressed multiple objectives of surveillance and monitoring, the documentation of the distribution of and threats to the marine megafauna, and capacity-building among government agents and local early-career scientists. During 22 days of survey effort over a two-year period, observers documented humpback whales Megaptera novaeangliae, bottlenose dolphins Tursiops truncatus, Atlantic humpback dolphins Sousa teuszii and common dolphins Delphinus delphis. Humpback whale presence was limited to the months of July to November. Bottlenose dolphins were present year-round and photo-identification of individuals indicated a closed, resident population, with an abundance estimate of 118 (CV = 21.6%, 95% CI 78–180). Small open-decked fishing vessels with gillnets were observed concentrated around river mouths within 2 km of shore, while commercial trawlers were at least 10 km offshore; all were confirmed to be registered and legal. Observations of marine turtles, flocks of marine birds, and floating logs and other debris were sparse. This multi-stakeholder collaboration to conduct a marine survey can serve as an effective model by which funding and logistic support from private industry paired with technical expertise from NGOs and academic institutions can benefit marine and coastal conservation.  相似文献   

Kelp Gulls (Larus dominicanus) killed and injured by discarded monofilament lines at a marine recreational fishery in northern Patagonia     

Pablo Yorio  Cristian Marinao  Nicolás Suárez 《Marine pollution bulletin》2014

Among marine debris, monofilament fishing lines often result in negative impacts on marine organisms. We characterized marine debris and incidence of lost and discarded monofilament lines along beaches used by recreational fishers, and report the impact of lines on Kelp Gulls (Larus dominicanus) at the Bahía San Blas protected area, site of one of the main shore-based recreational fisheries of the southwestern Atlantic. Over 55% of the marine debris recorded originated from recreational fishing activities. Balls of tangled monofilament lines were found at a rate of 40.5 items per km. A total of 27 adult Kelp Gulls were found entangled with monofilament. All individuals were tangled to vegetation within colony boundaries. Four of the gulls had a monofilament line protruding from the bill, showing that they may be also killed when trying to obtain bait. Our results indicate that lost or discarded monofilament lines in the Bahía San Blas recreational fishing area result in undesired impacts on coastal wildlife.  相似文献   

Assessing the ecosystem effects of the abalone Haliotis midae from its diet and foraging behaviour     

《African Journal of Marine Science》2013,35(2):205-214

The South African abalone Haliotis midae is commercially exploited and seriously threatened by overfishing. This not only affects the species itself but potentially the functioning of the ecosystem because of associated changes in community structure. The nature of effects that can follow the loss or reduction of a species depends in part on its position in the foodweb and its feeding behaviour. To assess the ecosystem effects of the adults and subadults of this previously abundant herbivore on the south-west coast of South Africa, we studied their diet and mode of food procurement by (a) in-field observations of adult and subadult abalone, (b) analysis of the gut contents of adults, (c) comparison of diet with the availability of algae, and (d) a mesocosm experiment on subadult feeding behaviour. Both field and dietary studies showed that adults subsist mainly by trapping drift kelp, but also occasionally graze on attached algae such as Plocamium spp., and feed in a manner that is highly selective, with drift kelp constituting 95–98% of the diet, and several species of common algae being avoided. In the mesocosm experiment, subadults preferentially fed on drift kelp, but emerged at night to a greater extent to graze on microflora if no drift material was available. Their propensity to emerge was, however, reduced if the rock lobster Jasus lalandii was present. Collectively, this evidence indicates that any ecosystem effects that subadults and adults of H. midae have as grazers will be weak because they feed mainly by trapping drift material, and the frequency of grazing and the incidence of consumption of attached algae are low.  相似文献   

From biomass mining to sustainable fishing — using abundance and size to define a spatial management framework for deep-water lobster     

《African Journal of Marine Science》2013,35(4):547-557

Based on the assumption that depleted stocks would have recovered during a six-year layoff from fishing, trapping for deep-water spiny lobster Palinurus delagoae and slipper lobster Scyllarides elisabethae off eastern South Africa resumed in 2004 until 2007. A generalised linear modelling approach was used to investigate the effects of year, sampling area, depth, month and trap soak-time on catch and lobster size, and to construct standardised abundance indices. The renewed trapping rapidly reversed partially restored nominal catch rates. Fishing strategy changed from targeting spiny lobsters during the first months of each fishing season to targeting slipper lobsters during later months. Small spiny lobsters were abundant in the southern area, identified as a recruitment hotspot. Spiny lobster abundance and size in this area increased over four years of fishing, but conversely, large adult spiny lobsters predominated in the central and northern areas, where trapping depleted their abundance over time. The adult populations in the central and northern areas are upstream from the recruitment hotspot, and are presumably a source of larvae. Slipper lobster abundance peaked in 2005, remained relatively constant across areas, and increased with depth. Trapping for deep-water lobster is unlikely to be sustainable in its present form. However, the clear gradients in spiny lobster size and abundance by sampling area and depth provide a good framework for spatial management planning.  相似文献