Marine fisheries in Kenya mainly comprise of the artisanal fishermen who use non-motorized boats. Competition of these dwindling resources has led to overfishing and degradation of coral reef ecosystems. One of the me...Marine fisheries in Kenya mainly comprise of the artisanal fishermen who use non-motorized boats. Competition of these dwindling resources has led to overfishing and degradation of coral reef ecosystems. One of the methods which have been used to enhance sustainable exploitation of fisheries resources is the use of Fish Aggregating Devices (FADs). The study was conducted in two areas along the Kenyan coast which are: Msambweni in the southern part and Kuruwitu (Vipingo) in the northern part of the Kenyan coast. A combination of systematic site surveys: structured and semi structured interviews with key informants (community leaders and resource users);participant observations;descriptions of daily and seasonal time use;and analyses of secondary sources, such as fisheries records, was used to gather information and triangulate results. The perception of the community about FADs was determined by conducting a socio-economic survey before and after deploying FADs. Colonization and biomass survey around the deployed FADs was undertaken and fish associated with FADs was recorded. Results indicate that nine families of fish aggregated around FADs and at different distances. Catch and effort at FADs have been evaluated by monitoring catch data from fishers on daily basis after deployments.展开更多
In the Indian Ocean, bigeye tuna supports one of the most important fisheries in the world. This fishery mainly consists of two components: longline and purse seine fisheries. Evidence of overfishing and stock depleti...In the Indian Ocean, bigeye tuna supports one of the most important fisheries in the world. This fishery mainly consists of two components: longline and purse seine fisheries. Evidence of overfishing and stock depletion of bigeye tuna calls for an evaluation of alternative management strategies. Using an age-structured operating model, parameterize dwith the results derived in a recent stock assessment,we evaluated the effectiveness of applying constant fishing mortality (CF) and quasi-constant fishing mortality (QCF) strategies to reduce fishing effort of purse seining with fish aggregating devices (FADs) at different rates. Three different levels of productivity accounted for the uncertainty in our understanding of stock productivity. The study shows that the results of CF and QCF are similar. Average SSB and catchduring simulation years would be higher if fishing mortality of FAD-associated purse seiningwas reduced rapidly. The banning or rapid reduction of purse seining with FAD resulted in a mean catch, and catch in the last simulation year, higher than that of the base case in which no change was made to the purse seine fishery. This could be caused by growth overfishing by purse seine fisheries with FADs according to the per-recruit analysis. These differences would be more obvious when stock productivity was low. Transferring efforts of FAD-associated purse seining to longline fisheries is also not feasible.Our study suggests that changes are necessary to improve the performance of the current management strategy.展开更多
A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high t...A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high tension mooring by fixed flotation. The analysis was performed by using a Morison equation type finite element model configured with truss elements. Input forcing parameters into the model consisted of both regular and irregular waves, with and without a steady current. Heave, surge and pitch dynamic calculations of the reef structure were made. Tension response results of the attached mooring line were also computed. Results were analyzed in both the time and frequency domain in which appropriate, linear transfer functions were calculated. The influence of the current was more evident in the tension and heave motion response data. This is most likely the result of the large buoyancy characteristics of the reef structure and the length of the mooting cable. Maximum mooting component tension was found to be 13.9 kN and occurred when the reef was subjected to irregular waves with a co-linear current of 1.0 m/s velocity. The results also showed that the system had little damping （in heave） with damped natural periods of 2.8 s. This combination of system characteristics promotes a possible resonating situation in typical open sea conditions with similar wave periods.展开更多
远洋捕捞国渔船能够通过租用、租赁的方式悬挂其他国家或捕鱼实体的旗帜,从而成为租赁船。为探究中西太平洋海域中国大陆金枪鱼围网租赁渔船的作业特征,通过分析2013—2016年中国大陆金枪鱼围网船队在中西太平洋的渔捞日志数据,对研究...远洋捕捞国渔船能够通过租用、租赁的方式悬挂其他国家或捕鱼实体的旗帜,从而成为租赁船。为探究中西太平洋海域中国大陆金枪鱼围网租赁渔船的作业特征,通过分析2013—2016年中国大陆金枪鱼围网船队在中西太平洋的渔捞日志数据,对研究期内各月份金枪鱼围网租赁船的数量、捕捞努力量及单位捕捞努力量渔获量(catch per unit effort,CPUE)等指标的时空变化趋势进行分析研究,结果表明:1)在研究期内,从2014年开始租赁船的绝对船数和船队占比都处于持续上升的过程;2)同一年中禁渔期和非禁渔期之间船队捕捞努力量的比值逐渐减小,禁渔期内船均捕捞努力量总体增加;3)不论在禁渔期还是全年,中国渔船租赁后的CPUE平均水平高于无租赁船的2013年水平;4)研究期内,非禁渔期的渔场分布相对均衡,而禁渔期的渔场分布具有年际变化,2015年的渔场重心向西偏移。这些结果表明中国大陆从2014年开始通过将围网渔船租赁给太平洋岛国在一定程度上减小了禁渔期对生产的影响。中国围网船队的发展模式仍需根据中西太平洋渔业委员会(Westernand Central Pacific Fisheries Commission,WCPFC)管理措施的变化作进一步的探索与调整。展开更多
Objective:To study the food habits of a sample of the dolphinfish (Coryphaena hippurus) around the Petrobrás PXIV oil platform located off Southern Brazil. Methods: We examined the stomach contents of 28 adult do...Objective:To study the food habits of a sample of the dolphinfish (Coryphaena hippurus) around the Petrobrás PXIV oil platform located off Southern Brazil. Methods: We examined the stomach contents of 28 adult dolphinfish caught around this platform between 2000 and 2001. Results: Results highlighted a diet consisting mainly of pelagic fish, although cephalopods and crustaceans are also present. A large amount of clupeids found in the stomachs could be due to baits used by fishermen that do fish around the platform. Conclusions:In this research we discuss the possibility of this occurrence being related to trophic opportunistic behavior. This could be a reason why adult dolphinfish are attracted by this platform since the whole structure does act as a fish aggregating device.展开更多
文摘Marine fisheries in Kenya mainly comprise of the artisanal fishermen who use non-motorized boats. Competition of these dwindling resources has led to overfishing and degradation of coral reef ecosystems. One of the methods which have been used to enhance sustainable exploitation of fisheries resources is the use of Fish Aggregating Devices (FADs). The study was conducted in two areas along the Kenyan coast which are: Msambweni in the southern part and Kuruwitu (Vipingo) in the northern part of the Kenyan coast. A combination of systematic site surveys: structured and semi structured interviews with key informants (community leaders and resource users);participant observations;descriptions of daily and seasonal time use;and analyses of secondary sources, such as fisheries records, was used to gather information and triangulate results. The perception of the community about FADs was determined by conducting a socio-economic survey before and after deploying FADs. Colonization and biomass survey around the deployed FADs was undertaken and fish associated with FADs was recorded. Results indicate that nine families of fish aggregated around FADs and at different distances. Catch and effort at FADs have been evaluated by monitoring catch data from fishers on daily basis after deployments.
基金Supported by the Shanghai Ocean University Graduate School (PhD Dissertation Grant)the Project of Shanghai Science and Technology Innovation(No.12231203900)+4 种基金the National Natural Science Foundation of China(No.NSFC41276156)the Industrialization Program of the National Development and Reform Commission(No.2159999)the Shanghai Leading Academic Discipline Projectthe National Distant-water Fisheries Engineering Research Center,the Scientific Observing and Experimental Station of Oceanic Fishery Resources,Ministry of Agriculture,China.Y.supported by the Shanghai Leading Teacher Program
文摘In the Indian Ocean, bigeye tuna supports one of the most important fisheries in the world. This fishery mainly consists of two components: longline and purse seine fisheries. Evidence of overfishing and stock depletion of bigeye tuna calls for an evaluation of alternative management strategies. Using an age-structured operating model, parameterize dwith the results derived in a recent stock assessment,we evaluated the effectiveness of applying constant fishing mortality (CF) and quasi-constant fishing mortality (QCF) strategies to reduce fishing effort of purse seining with fish aggregating devices (FADs) at different rates. Three different levels of productivity accounted for the uncertainty in our understanding of stock productivity. The study shows that the results of CF and QCF are similar. Average SSB and catchduring simulation years would be higher if fishing mortality of FAD-associated purse seiningwas reduced rapidly. The banning or rapid reduction of purse seining with FAD resulted in a mean catch, and catch in the last simulation year, higher than that of the base case in which no change was made to the purse seine fishery. This could be caused by growth overfishing by purse seine fisheries with FADs according to the per-recruit analysis. These differences would be more obvious when stock productivity was low. Transferring efforts of FAD-associated purse seining to longline fisheries is also not feasible.Our study suggests that changes are necessary to improve the performance of the current management strategy.
基金supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD)(KRF-2007-313-F00073)Technology Development Program for Food,Agriculture,Forestry and Fisheries,Republic of Korea
文摘A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high tension mooring by fixed flotation. The analysis was performed by using a Morison equation type finite element model configured with truss elements. Input forcing parameters into the model consisted of both regular and irregular waves, with and without a steady current. Heave, surge and pitch dynamic calculations of the reef structure were made. Tension response results of the attached mooring line were also computed. Results were analyzed in both the time and frequency domain in which appropriate, linear transfer functions were calculated. The influence of the current was more evident in the tension and heave motion response data. This is most likely the result of the large buoyancy characteristics of the reef structure and the length of the mooting cable. Maximum mooting component tension was found to be 13.9 kN and occurred when the reef was subjected to irregular waves with a co-linear current of 1.0 m/s velocity. The results also showed that the system had little damping （in heave） with damped natural periods of 2.8 s. This combination of system characteristics promotes a possible resonating situation in typical open sea conditions with similar wave periods.
文摘远洋捕捞国渔船能够通过租用、租赁的方式悬挂其他国家或捕鱼实体的旗帜,从而成为租赁船。为探究中西太平洋海域中国大陆金枪鱼围网租赁渔船的作业特征,通过分析2013—2016年中国大陆金枪鱼围网船队在中西太平洋的渔捞日志数据,对研究期内各月份金枪鱼围网租赁船的数量、捕捞努力量及单位捕捞努力量渔获量(catch per unit effort,CPUE)等指标的时空变化趋势进行分析研究,结果表明:1)在研究期内,从2014年开始租赁船的绝对船数和船队占比都处于持续上升的过程;2)同一年中禁渔期和非禁渔期之间船队捕捞努力量的比值逐渐减小,禁渔期内船均捕捞努力量总体增加;3)不论在禁渔期还是全年,中国渔船租赁后的CPUE平均水平高于无租赁船的2013年水平;4)研究期内,非禁渔期的渔场分布相对均衡,而禁渔期的渔场分布具有年际变化,2015年的渔场重心向西偏移。这些结果表明中国大陆从2014年开始通过将围网渔船租赁给太平洋岛国在一定程度上减小了禁渔期对生产的影响。中国围网船队的发展模式仍需根据中西太平洋渔业委员会(Westernand Central Pacific Fisheries Commission,WCPFC)管理措施的变化作进一步的探索与调整。
基金Supported by Universidade do Vale do Itajaí’s Center for Marine Sciences,Fernando L.Diehl.Petrobrás-Petróleos do Brasil,S.A.(PB/2000/01/10).
文摘Objective:To study the food habits of a sample of the dolphinfish (Coryphaena hippurus) around the Petrobrás PXIV oil platform located off Southern Brazil. Methods: We examined the stomach contents of 28 adult dolphinfish caught around this platform between 2000 and 2001. Results: Results highlighted a diet consisting mainly of pelagic fish, although cephalopods and crustaceans are also present. A large amount of clupeids found in the stomachs could be due to baits used by fishermen that do fish around the platform. Conclusions:In this research we discuss the possibility of this occurrence being related to trophic opportunistic behavior. This could be a reason why adult dolphinfish are attracted by this platform since the whole structure does act as a fish aggregating device.
