Nutrient digestibility of angling baits for carp, Cyprinus carpio, with implications for groundbait formulation and eutrophication control

Abstract  To evaluate the suitability of angling groundbaits as a fish feed and the potential for nutrient loss, the macronutrient digestibility of four groundbaits was investigated in carp, Cyprinus carpio L., using a sieving method of faeces collection and chromic oxide. Apparent digestibility coefficients (ADCs) of protein and lipids were >80% for all angling baits. ADCs of nitrogen-free extracts and phosphorus (P) differed significantly between the test diets, probably because of divergent feed compositions and ingredient treatments. The generally high digestibility estimates indicated that fish feeding on angling groundbait will benefit from this food source. The differences in nutrient digestibility suggested that type of groundbait and ingredient used will have a major effect on potential eutrophication and fish production caused by groundbaiting. The principle of groundbaits to protect the environment should be to minimise the P-content of the groundaits and maximising P-digestibility and P-retention efficiency.     

Relationships between catch and effort in Fijian multispecies reef fisheries subject to different levels of exploitation

Abstract The catch-per-unit-effort (CPUE) and value-of-catch-per-unit-effort (VPUE) of reef-associated fish species from six Fijian native fishing grounds ( qoliqoli ) subject to different fishing intensities were determined using records of fishing activity from a voluntary logbook scheme. Line and spear fishing techniques were used for more than half the total fishing time (h person^-1 d^-1) in all qoliqoli , and yet the favoured technique in a given qoliqoli was frequently less efficient (lower CPUE) than other techniques. The popularity of relatively ineffective fishing methods implies that fishermen did not always attempt to maximize their catch rates. To compare fishing effort in different qoliqoli , all effort was rescaled on the basis of its recorded efficiency (measured as multispecies CPUE) and expressed as hours equivalent to boat-based spear fishing over coral by day to catch fish for sale. Total fishing intensity in the six qoliqoli ranged from 72 to 4310 h km^-2 reef year^-1. The relationship between catch and effort was linear at all fishing intensities, suggesting that the qoliqoli were all fished on a sustainable basis. Furthermore, whilst there was a significant difference in CPUE and VPUE between the one or two qoliqoli with lowest fishing intensity and all the others, there were no significant differences between these other qoliqoli in terms of the VPUE of the saleable multispecies boat catch or the CPUE of species from piscivorous and carnivorous genera ( Epinephelus, Lethrinus and Plectropomus ) which the fishermen prefer to catch.     

2010—2019年江苏省渔业船舶水上安全事故分析及对策建议

依据中国渔政指挥系统江苏省渔业船舶水上安全事故的统计资料,对2010—2019年事故的发生时间、事故起数、死亡人数、事故类型和事故等级等方面进行了统计分析。结果表明,江苏省渔业船舶水上安全事故以一般等级事故居多,事故发生时间呈现一定规律性,渔船自身安全隐患突出,从业人员岗位技能不足,渔船安全管理责任不到位。基于分析结果,提出压降一般等级事故,遏制较大等级以上事故,提高风险管控和事故防范能力的对策建议。     

基于PLC的蟹笼渔船诱饵填盒与塞笼自动化流水线方案设计

蟹笼渔船诱捕饵料在使用过程需要经过破冰分离、切块、填盒、塞笼等工序,效率低、劳动强度大.为提升蟹笼渔船的生产效率,需要实现饵料使用自动化.提出了一种实现饵料使用自动化的流水线生产方案,并通过Pro/ENGINEER Wildfire 5.0进行流水线的结构设计建模与原理分析,采用GX works3基于三菱FX5U系列P...     

基于多元变量的南极磷虾拖网作业状态影响因素分析

拖网作业过程中的网位、网身状态、拖网整体状态是评价拖网性能优劣的重要指标。以南极磷虾拖网为例,通过测量拖网不同部位（上纲、第3~4节网身连接处和网囊口上部中点）深度,以部位间深度差表示拖网作业状态,分析捕捞操作、海洋环境和渔获量对拖网作业状态的影响,确定中层拖网作业过程中状态的变化趋势。结果表明：（1）上纲与第3~4节网身连接处深度差范围为-0.20~8.02 m,上纲与网囊口上部中点深度差范围为6.49~30.16 m;（2）曳纲长度、拖速、风速、150 m水层流速对磷虾拖网上纲深度影响显著（P< 0.05）;上纲深度与曳纲长度和150 m水层流速呈正相关关系,与拖速呈负相关关系,随风速增加,上纲深度先减小后增大;（3）拖速、200 m水层流速和浪高对上纲与第3~4节网身连接处深度差影响极显著（P< 0.05）;上纲与第3~4节网身连接处深度差具有随拖速和200 m水层流速的增加,先增大后减小的趋势;其中拖速2.6 kn和200 m水层流速0.3 kn时,上纲与网囊口上部中点深度差最大,2 m浪高时,深度差最小;（4）渔获量与上纲和网囊口上部中点深度差呈正相关关系;（5）曳纲长度是影响拖网作业状态的最重要因素,其次是拖网速度、风速、浪高和水流速度。     

海冰与风场对布兰斯菲尔德海峡磷虾渔场作业适宜性的影响

全球变暖越来越受到人们的关注,南极海冰和风场作为气候变化的关键因子,显著影响着渔船作业的安全及经济效率.相较于连续泵吸捕捞渔船,我国普遍采用传统渔船开展南极磷虾捕捞作业,该作业易受到外界环境的影响.本实验针对磷虾捕捞作业的适应性,基于1989—2020年美国国家冰雪中心海冰密集度数据及欧洲中期天气预报中心风场数据,获得...     

Interannual variability in stock abundance of the neon flying squid, Ommastrephes bartramii, in the North Pacific Ocean during 1979–1998: impact of driftnet fishing and oceanographic conditions

Variability in catch-per-unit-effort (CPUE) was examined for the autumn cohort of Ommastrephes bartramii collected with research driftnets during 1979–1998 along five longitudinal transects passing through the Subarctic, Transitional and Subtropical Domains in the North Pacific. CPUE was generally low during the period of intensive commercial driftnet fishing (1980–1992) and increased following the 1992 moratorium on the use of large-scale driftnets. However, CPUE levels were low for the cohorts hatched in 1992 and 1996 (captured in subsequent years owing to a one-year life of O. bartramii ) that experienced low sea surface temperatures from hatching to recruitment. Among similar-aged squid collected from 180° and 179°30'W in June, mantle lengths were significantly greater in 1997 than during 1995–96. These findings suggest that the driftnet fishery and sea surface temperatures from hatching to recruitment strongly affected stock abundance and possibly growth.     

大西洋南部金枪鱼渔场的生产调查报告

根据随船调查材料，对大西洋南部金枪鱼延绳钓渔业从捕捞技术，渔场环境因素，渔获物情况、初加工、销售等方面做出了总结。本文着重分析了各个作业渔场的渔获情况，判断出八个中心渔场的位置，并就大眼金枪鱼在这几个中心渔场的生物学特征做了统计分析，从而为用地理信息技术预报渔场提供了实施依据。     

Relationship between soak time and number of enmeshed animals in experimentally lost gill nets

In order to determine the effects of ghost fishing by lost gill nets, the relationship was examined between soak time and number of enmeshed animals in experimentally lost gill nets by using diving observations. Two experimental gill nets were set at 13 m depth in Tateyama Bay, Chiba Prefecture, Japan for approximately 200 days. One gill net was deployed in a small trough surrounded by artificial reefs, and the other was deployed on an adjacent open sandy bed. Twelve species of crustaceans, six species of gastropods, and five species of bony fish were enmeshed in the experimental gill nets. The number of enmeshed animals in the artificial reef gill net was substantially larger than that in the sandy bed gill net. The number of enmeshed animals in the experimental gill nets increased rapidly within one month after deployment, and then declined gradually showing fluctuations caused by the decrease in newly enmeshed animals, and the drop off from gill nets caused by the decomposition of dead animals. The decrease in the number of enmeshed animals was expressed by logarithmic equations, and based on these equations, the duration of capture function for the lost gill nets was calculated to be 284–561 days in the artificial reef gill net and 200 days in the sandy bed gill net. The duration of capture function for the lost gill nets for non-commercial by-catch species such as small crustaceans and gastropods was longer than for commercial species such as Japanese spiny lobster and bony fish.