Model simulations to determine optimal fishing effort and season duration for a tropical shrimp fishery

Kuwait's shrimp fishery presents typical tropical shrimp fishery characteristics with highly variable recruitment, fast growth and strong seasonal patterns. Both the General Production Model and Age-structured Model were chosen to assess the stock status of the Kuwait's shrimp fishery. The estimated Maximum Sustainable Yield(MSY) was 2 518 metric ton(t) with a corresponding fishing eff orts( f MSY) 7 265 standard boat-days from the General Production Model. Similar results from the Age-structured Model were 1 936 t and 6 449 boat-days respectively. Comparing these results with the average annual shrimp landings(1 772 t) and average fishing eff ort(9 710 boat-days) in the past 10 years, we concluded that the fishery was overfished. Model simulations to show the changes of recruitment, biomass and possible catch under different fishing eff ort scenarios indicated possible stock collapse if the fishing eff ort continually increase. But both shrimp recruitment and biomass will increase if the current fishing eff ort is reduced. Model simulations also showed a possible increase of MSY by delaying the opening or by closing the season earlier. Based on these results, recommendations to improve the management of Kuwait's shrimp fishery are presented.

山东半岛南部海域鱼类群落生物量粒径谱季节变化

为了解山东半岛南部海域鱼类群落粒径结构特征,本文根据2016—2017年渔业资源底拖网季度调查数据,构建了山东半岛南部海域鱼类生物量粒径谱,分析了该海域鱼类群落的粒径结构特征及其季节变化。研究表明,山东半岛南部海域Sheldon型鱼类生物量粒径谱呈双峰模式,鱼类粒径范围为2~12粒径级,粒径分布相对均匀,出现波峰的粒径区间存在季节差异,春、夏季第一个波峰出现在3~4粒径级,主要由细纹狮子鱼(Liparis tanakae)、方氏云鳚(Pholis fangi)和大泷六线鱼(Hexagrammos otakii)等种类组成。秋、冬季第一个波峰出现在5~6粒径级,主要由小眼绿鳍鱼(Chelidonichthys spinosus)、长蛇鲻(Saurida elongata)和斑鰶(Konosirus punctatus)等种类组成。四个季节的第二个波峰均由细纹狮子鱼、黄鮟鱇(Lophius litulon)和大头鳕(Gadus macrocephalus)等鱼类个体组成。全部鱼类群落标准化生物量粒径谱的斜率和截距存在季节差异,其中夏季粒径谱陡峭,截距值显著高于其他季节,而冬季粒径谱最平缓,截距值最小,粒径谱斜率和截距的变化主要受当年生幼鱼群体的影响。在山东半岛南部海域,底层鱼类群落与全部鱼类群落的标准化生物量粒径谱的变化趋势相似。在同一季节,底层鱼类群落与全部鱼类群落的标准化生物量粒径谱斜率和截距之间无显著性差异(P>0.05),而暖温性鱼类群落与全部鱼类群落之间存在显著性差异(P<0.05)。山东半岛南部海域的全部鱼类群落粒径结构以小粒径鱼类为主,大型鱼种和大个体较少。鱼类的种类组成有明显的季节变化,当年生幼鱼及洄游性鱼类的个体数量变化是影响该海域鱼类群落粒径结构的主要因素。

基于改进YOLOv8的渔港船舶进出港目标检测与统计方法

为减轻渔港执法人员在渔船进出港统计工作中的压力,提出了一种基于改进YOLOv8模型的渔港船舶进出港目标检测与统计模型YOLOv8n-Bi-FPN-EMA,该模型采用加权双向特征金字塔网络结构(Bi-FPN),引入高效多尺度注意模块(EMA)以提高模型的目标检测准确性和稳定性,并结合BoT-SORT跟踪算法实现对不同类型船舶进出渔港的分类统计。结果表明:与YOLOv8n模型相比,YOLOv8n-Bi-FPN-EMA模型的准确率提高了5.0%,mAP@0.5提高了0.2%,对执法船、拖船和渔船的识别准确率分别提高了9.9%、4.9%、0.3%。其中,对渔船的识别准确率为99.1%,召回率为84.4%,mAP@0.5为97.8%。研究表明,YOLOv8n-Bi-FPN-EMA模型在渔船识别上有较好的表现,可用于渔船识别与进出港统计的辅助工作。

仿生机器鱼步态控制及闭环运动控制方法综述

鱼类所具有的推进效率高、机动性强、环境扰动小等优点引发了国内外学者对仿生机器鱼的研究。底层步态控制方法和闭环运动控制方法是当前机器鱼控制研究的两大热点。按照推进模式的分类方法概述各类机器鱼的样机研制情况以及其性能优劣,介绍机器鱼的推进机理及其水动力学研究进展,进而重点探讨轨迹逼近方法和中枢模式发生器这2种底层步态控制思路,综述机器鱼的典型闭环运动控制方法。中枢模式发生器具有更强的灵活性、稳定性和可操作性,易于引入反馈项而实现闭环控制,在机器鱼底层步态控制中占主导地位。针对机器鱼的显著特点改进后的基于学习的控制方法与多种方法相结合后的混合控制方法具有更为广阔的发展前景,符合仿生机器鱼智能化的发展方向。根据工作条件和运动要求建立合理的步态控制系统以及准确高效的闭环运动控制系统可提高机器鱼的整体性能。

论销售在禁渔区或禁渔期非法捕捞渔获物的法律责任

由于现行《中华人民共和国渔业法》第三十八条第二款关于处罚销售在禁渔区或禁渔期非法捕捞的渔获物行为的罚则缺失,导致这种行为没有很好地受到法律规制,严重破坏了渔业资源的可持续发展。文章通过阐述销售禁渔区或禁渔期非法捕捞的渔获物行为的相关概念和危害,分析《渔业法》完善罚则的必要性,并提出法律责任的构成要素和立法建议。

影响大型溞繁殖的多因素分析

为研究不同环境因素对大型溞生长、繁殖情况的影响,依据经济合作与发展组织(OECD)化学品测试方法No.211大型溞(Daphnia magna)繁殖试验对大型溞繁殖情况进行了测试。经过研究发现:第4季度较其他季度,大型溞繁殖量最低,初次产溞时间最晚,固有增长率最低;经单因素方差分析得出,第4季度的大型溞繁殖量、初次产溞时间、固有增长率均与其他季度存在显著性差异(p<0.05)。此外,密闭环境与非密闭环境相比,密闭环境下的亲溞繁殖量更少;经单因素方差分析得出,密闭环境与非密闭环境下亲溞的繁殖量存在显著性差异(p<0.05)。结果表明,即使在实验室稳定控制的环境条件下,季节性变化、密闭/非密闭环境依然对大型溞产生了一定的影响。

Wave and Current Effects on Floating Fish Farms

The paper is partly a review on hydrodynamic and structural aspects of fish farms. In addition, new numerical results are presented on the stochastic behavior of bending stresses in the floater of a realistic net cage in extreme wave conditions. The behavior of traditional-type fish farms with net cages and closed fish farms in waves and currents is discussed. Hydroelasticity can play a significant role for net cages and closed membrane-type fish farms. The many meshes in a net cage make CFD and complete structural modeling impracticable. As an example, a hydrodynamic screen model and structural truss elements are instead used to represent the hydrodynamic loading and the structural deformation of the net. In addition, the wake inside the net due to current plays an important role. The described simplified numerical method has been validated by comparing with model tests of mooring loads on a single net cage with two circular elastic floaters and bottom weight ring in waves and currents. It is discussed which parts of the complete system play the most important roles in accurately determining the mooring loads. Many realizations of a sea state are needed to obtain reliable estimates of extreme values in a stochastic sea. In reality, many net cages operate in close vicinity, which raises questions about spatial variations of the current and wave environment as well as hydrodynamic interaction between the net cages. Live fish touching the netting can have a non-negligible influence on the mooring loads. It is demonstrated by numerical calculations in waves and currents that a well boat at a net cage can have a significant influence on the mooring loads and the bending stresses in the floater. The latter results provide a rational way to obtain operational limits for a well boat at a fish farm. Sloshing has to be accounted for in describing the behavior of a closed fish farm when important wave frequencies are in the vicinity of natural sloshing frequencies. The structural flexibility has to be considered in determining the natural sloshing frequencies for a membrane-type closed fish farm. Free-surface non-linearities can matter for sloshing and can, for instance,result in swirling in a certain frequency domain for a closed cage with a vertical symmetry axis.

Evaluating impacts of pulse fishing on the effectiveness of seasonal closure

Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.

The effects of season on fatty acid composition and ω3/ω6 ratios of northern pike(Esox lucius L.,1758) muscle lipids

In the present study, the effects of season on fatty acid composition, total lipids, and ω3/ω6 ratios of northern pike muscle lipids in Klzlhrmak River （Klrlkkale, Turkey） were investigated. A total of 35 different fatty acids were determined in gas chromatography. Among these, palmitic, oleic, and palmitoleic acids had the highest proportion. The main polyunsaturated fatty acids （PUFAs） were found to be docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid. There were more PUFAs than monounsaturated fatty acids （MUFA） in all seasons. Similarly, the percentages of ω3 fatty acids were higher than those of total ω6 fatty acids in the fatty acid composition. ω3/ω6 ratios were calculated as 1.53, 1.32, 1.97, and 1.71 in spring, summer, autumn and winter, respectively. Overall, we found that the fatty acid composition and ω3/ω6 fatty acid ratio in the muscle of northern pike were significantly influenced by season.

Clupeid fish hosts a Peniculus sp.(Pennellidae,Siphonostomatoida, Copepoda)—First report on new host and season dependent prevalence

Pennellid copepod Peniculus fistula fistula(Nordmann, 1832)(Synonym: Peniculus fistula Nordmann, 1832,Aphia ID: 745880), a worldwide distributed species, has been recovered from at least 19 teleost families. The present paper reports for the first time from the Malabar coast(South India), not only the existence of a new host family, Clupeidae, hosting this parasitic copepod species(P. fistula fistula) but also their season dependent hosting. A total of 123 marine fish species, belonging to 77 genera and 38 families surveyed along the Malabar coast, only the clupeid, Anadontostoma chacunda(Hamilton, 1822) was shown to be infected by this copepod species;all the recovered(copepod) parasites were invariably found attached at the mid portion of the caudal fin lobes and lying parallel to the host body, indicating the strict site-specific parasitisation. There is a discrete seasonality in the prevalence(P<0.05) as the sign of infection was noticed during the period from September to May with relatively high prevalence during winter months(November–January). During the monsoon months(June–August), the host fish was found completely free from Peniculus infection. Interestingly, all the 229 recovered specimens(P. fistula fistula) were gravid females having paired uniserrate egg sacs with the length more than its own body length.

Diet of fish populations in posidonia oceanica meadows off the Island of Ischia (Gulf of Naples, Italy):

The gut contents of fish in three Posidonia oceanica meadows off the island of Ischia (Bay of Naples, Italy) were investigated. A total of 926 individual fish belonging to 28 species was sampled by bottom trawl in the leaf canopy. Labridae, Pomacentridae, Scorpaenidae, and Serranidae were the best represented families (41%, 38%, 8% and 6% of the total number of individuals, respectively). Of the 94 taxa detected in the gut contents, 42 were identified to the species level. The most common food items were decapod crustaceans (15% of the gut contents, on average), copepods (13%), amphipods (14%), brown fragments of P. oceanica (6%), and ostracods (6%). The most abundant species of labridae, Symphodus ocellatus and S. rostratus, showed a broad spectrum of prey. This generalist feeding may positively influence their numerical abundance. Seasonal variations in the diets of fish, also at prey-species level, were demonstrated. The fish taxon plays essentially a macro-carnivore trophic role. In the investigated seagrass meadows the main trophic fluxes start from plant detritus, macrophyta, and microphyta (as primary producers) towards crustacean decapods, copepods, ostracods, and gammarid amphipods (as secondary producers) to fish. A low recycling rate (4%) within the fish community was observed. Larger fish predators (e.g., Sparidae), swimming over the leaf canopy, are the main exporters to adjacent coastal systems.

Diversity and Influence of Environmental Factors on the Spatio-Temporal Distribution of the Ichthyofauna of Malonda Lagoon (Congo Brazzaville)

This study was initiated with the aim of studying the diversity and spatio-temporal distribution of fish in the Malonda lagoon, one of the coastal ecosystems of the Base Guinea in the Republic of Congo. The fish were sampled over a period of two years in three zones each including three stations known as: Mangrove, Grass and Full water. One station upstream towards the freshwater zone, one station downstream towards the mouth and one station in the containment zone. The catches were made using monofilament gillnets of 8, 10, 20 and 30 mm mesh size. During the rainy season, 1516 specimens belonging to 29 species, 17 families and 12 orders were collected. In the dry season, 768 specimens belonging to 20 species, 11 families and 8 orders were collected. For both seasons, the family Cichlidae is the most diversified. The marine forms are the most represented compared to the continental forms. Redundancy Analysis with forward selection coupled with Monte Carlo permutation tests showed that in the rainy season four variables influenced the distribution of species (Depth: 48%, Vase: 16%, Nitrogen: 10% and Transparency: 10%);in the dry season three variables influenced the distribution of species (Vase: 38%, Nitrogen: 14% and Oxygen: 11%). Ecological indices showed that the Malonda lagoon is already undergoing either anthropic or natural impacts, its state of ecological integrity is disturbed, the values of Shannon diversity and Equitability indices are not close to maximum values. The results of this study will serve as an ecological database for the proper management of these ecosystems.

辽东湾鱼类群落结构的季节变化特征

为探究辽东湾鱼类群落结构的季节变化特征,于2020年5月(春季)、8月(夏季)和10月(秋季)在该海域进行了3个航次的底拖网调查,据此分析辽东湾鱼类种类组成、优势种、多样性和群落空间结构随季节变化的情况,并计算群落季节更替与迁移指数,建立鱼类群落丰度-生物量比较曲线。调查结果显示:辽东湾春、夏、秋3个季节共捕获鱼类58种,其中春季34种、夏季49种、秋季46种;优势种春季为短吻红舌鳎、黄鲫和皮氏叫姑鱼,夏季为矛尾虾虎鱼、短吻红舌鳎、白姑鱼、皮氏叫姑鱼和斑鱼祭,秋季为矛尾虾虎鱼、短吻红舌鳎、六丝钝尾虾虎鱼、黄鲫和皮氏叫姑鱼;鱼类群落的多样性指数为1.34~1.63,丰富度指数为1.44~1.68,均匀度指数为0.60~0.64;辽东湾鱼类可分为3个群落类型,靠近湾顶的北部近岸浅滩水域群落、辽东湾中南部深水区群落和辽东湾湾口深水区群落,其中春季和夏季可分为3个群落组,秋季分为2个群落组;鱼类群落的空间分布在春、夏季与底层温度相关性系数最高(春季R=0.270、夏季R=0.408),在秋季与水深相关系数最高(秋季R=0.376);丰度-生物量比较曲线结果显示,辽东湾鱼类丰度优势度曲线均位于生物量曲线之上,表明该海域鱼类群落处于受严重干扰状态。

外伶仃海洋牧场附近海域渔业资源季节动态变化分析

珠江口外伶仃海域是重要的传统渔场和渔业资源洄游通道,近年来在人类活动和气候变化的双重压力下生境发生了巨大变化。为深入了解渔业资源的季节变动规律,根据珠江口外伶仃海洋牧场附近海域2020和2021年的调查数据,采用空间分析方法,探究了不同渔获种类的季节动态变化和特征分布,并对渔场重心进行分析归纳。结果表明,总体资源密度春季高于秋季,呈斑点状分布,春季渔场重心分布集中于南部海域,秋季渔场重心向西北方向移动;鱼类资源密度分布与总资源密度相似,春季鱼类资源重心位于西南方向,秋季向西北方向移动;蟹类春季资源密度整体分布均匀,秋季资源密度有所提高,高密度海域有所增加,呈片状分布,资源重心由西部向东北方向移动;虾类春季资源密度低于秋季,资源重心向东北方向移动;虾蛄类整体资源密度较低,资源重心春季位于西部海域,秋季向东北方向移动;头足类春季资源密度高于秋季,均呈片状分布,资源重心从东向西移动。

渔民对伏季休渔政策的满意度研究——基于黄、渤海渔村问卷调查的分析

我国伏季休渔期政策自实施以来,其休渔范围、时间和类型不断扩大和完善,政策的落地和执行对我国渔业资源可持续发展做出了重要贡献。渔民作为休渔期政策实施的核心载体,他们对休渔期政策的满意度是我国持续推行伏季休渔政策的关键。文章以辽宁省大连市541位渔民的调研数据为基础,运用logistic模型对伏季休渔政策满意度进行了研究,结果表明:(1)渔民对伏季休渔政策总体满意度比较高,77.4%的渔民持有满意态度;(2)健康状况不佳的渔民对伏季休渔政策满意度较低;(3)渔业收入占比高的渔民对伏季休渔政策满意度较低;(4)对政府部门工作的满意度与伏季休渔政策满意度呈明显正相关关系。基于上述研究结果,对伏季休渔制度提出相应的政策建议。

稻鱼共作模式下头季稻施氮量对全年水稻产量的影响

【目的】明确稻渔综合种养模式优质稻的适宜施氮量,为进一步优化“优质稻+再生稻+鱼”优质高效配套技术体系提供参考。【方法】以“壮香优1205”为试验品种,设置N 0 kg/hm^(2)、N 90 kg/hm^(2)、N 120 kg/hm^(2)、N 150 kg/hm^(2)和N 180 kg/hm^(2)5个不同施氮组,进行稻鱼共作模式“优质稻+再生稻+鱼”头季稻不同施肥量的对比试验,对头季稻、再生稻的生长情况和产量进行观察记载、分析研究。【结果】结果表明:肥料的投入跟产出并非直线关系,当肥料的用量超过一定范围时,效益反而递减,以施N 150 kg/hm^(2)、N∶P_(2)O_(5)∶K_(2)O=1.0∶0.4∶1.0的处理组产量最高,为8404.2 kg/hm^(2),增产率高达21.0%,其纯收益亦最高,每公顷为20960.1元,施肥效果最佳。【结论】在稻渔综合种养模式优质稻生产上应适当减少氮肥施用,合理搭配磷肥、钾肥,以节本增效和降低对水土的污染。在本试验条件下,以施N 150 kg/hm^(2)、N∶P_(2)O_(5)∶K_(2)O=1∶0.4∶1为“优质稻+再生稻+鱼”种养模式的最优方案。

一种四川酸菜鱼面调料的研制

以酸菜、鱼肉和泡小米辣为主要原料,研制一种酸菜鱼面调料。在单因素实验和正交试验的基础上,结合正交趋势及方差分析,优化调料配方为:酸菜泥210 g、鱼泥100 g、小米辣泥18 g、油180 g、泡萝卜泥50 g、泡姜泥10 g、生姜泥25 g、大蒜泥15 g、番茄酱20 g、泡豇豆50 g、酸菜丁100 g、泡红辣椒15 g、精盐5 g、胡椒粉4 g、花椒油8 g、饮用水170 g。该配方对企业开发、生产相关产品具有一定的参考价值。

稻鱼共作头季稻栽植密度及留桩高度对水稻产量的影响

通过开展稻鱼共作头季稻不同栽植密度及留桩高度小区对比试验,为进一步优化稻鱼共作“优质稻+再生稻”绿色轻简高效配套技术体系提供科学依据。试验设置6个栽植密度(15万~27万穴·hm^(-2))和5个留桩高度(0~30 cm),对头季稻及再生稻进行了观察记载、分析研究。水稻全年产量以种植密度C处理(21万穴·hm^(-2))最高(9628.50 kg·hm^(-2)),B处理(18万穴·hm^(-2))次之(9614.3 kg·hm^(-2)),处理D (24万穴·hm^(-2))再次之(9555.0 kg·hm^(-2));随着留桩高度的增加,再生稻产量随之增加,以留桩高度25 cm处理产量最高(1988.8 kg·hm^(-2))。在水稻产量构成因素中,对产量的贡献自高至低依次为每公顷有效穗数>每穗实粒数>千粒重;随着留桩高度的降低,水稻齐穗期亦相应推迟(2~9 d);在本试验条件下,留桩高度在20 cm以上的3个处理均能正常灌浆结实。稻鱼共作头季稻栽植密度以18万~21万穴·hm^(-2)为适宜;为了确保水稻能安全避过寒露风并获得高产,留桩高度以20~25 cm为适宜。

海洋来源产蛋白酶Bacillus zhangzhouensis sp.在速酿鱼露中的应用

文章从海洋来源的8株芽孢杆菌中筛选到了1株碱性蛋白酶活力最好的漳州芽孢杆菌,将其应用到鱼露发酵过程中,利用响应面法优化最佳发酵条件为接种量4.15%、pH 9.13、温度36.3℃。在此最佳发酵条件下,分别将鱼露发酵15 h、3 d、7 d、15 d和30 d,结果表明,在发酵第7天时,鱼露的氨基酸态氮和总氮含量较高,对鱼露调味品市场的开发具有重大意义。

预制黑鱼产品开发及其工艺研究

烤黑鱼产品属于预制菜品,该产品主要包括烤制黑鱼和调味料包。烤制黑鱼以新鲜黑鱼为原料,通过探究腌制、烤制、冷却、包装、速冻等加工要点,对比不同烤制温度和时间下烤鱼的质构和色度区别,结合感官评价,确定最佳烤制温度为280℃,最佳烤制时间为15 min。调味料包以花椒、干辣椒、豆瓣酱、郫县豆瓣酱4个关键因素进行正交实验,得出烤鱼调料包中最佳配料的比例为花椒8 g,干辣椒25 g,豆瓣酱20 g,郫县豆瓣酱100 g。