A spatial- and age-structured assessment model to estimate the impact of illegal fishing and ecosystem change on the South African abalone Haliotis midae resource

The management of abalone stocks worldwide is complicated by factors such as illegal fishing combined with the difficulties of assessing a sedentary (but not immobile) resource that is often patchily distributed. The South African abalone Haliotis midae fishery is faced with an additional problem in the form of a relatively recent movement of rock lobsters Jasus lalandii into much of the range of the abalone. The lobsters have heavily reduced sea urchin Parechinus angulosus populations, thereby indirectly negatively impacting juvenile abalone which rely on the urchins for shelter. A model is developed for abalone that is an extension of more standard age-structured assessment models because it explicitly takes spatial effects into account, incorporates the ecosystem change effect described above and estimates the magnitude of substantial illegal (‘poached’) catches. The model is simultaneously fitted to catch per unit effort and Fishery-Independent Abalone Survey abundance data, as well as to several years of catch-at-age (cohort-sliced from catch-at-size) data for the various components of the fishery and different spatial strata. It constitutes the first quantitative approach applied to the management of this commercially valuable resource in South Africa and has provided a basis for management advice over recent years by projecting abundance trends under alternative future catch levels.     

Few data but many fish: marine small-scale fisheries catches for Mozambique and Tanzania

The fisheries data supplied to the Food and Agriculture Organization of the United Nations (FAO) by national agencies have served as the primary tool for many global and regional studies. However, it is recognised that these data are incomplete and often underestimate actual catches, particularly for small-scale fisheries. This study reconstructed total marine fisheries catches from 1950 to 2005 for Mozambique and the United Republic of Tanzania, by applying an established catch reconstruction approach utilising all available quantitative and qualitative data, combined with assumption-based estimations and interpolations. Since the 1950s, Mozambique has reported primarily industrial catches and has substantially under-reported the country's small-scale fishing sector due to lack of resources and civil war. In Tanzania, Zanzibar's recorded fisheries statistics prior to 2000 are absent from Tanzania's marine fisheries catches reported to FAO, and total mainland catches are at least one-third larger than officially reported. Based on our reconstruction, since 2000, Mozambique caught between 150 000 and 172 000 t y^?1, while the United Republic of Tanzania caught at least 95 000 t y^?1. For the period 1950–2005, reconstructed total marine catches were 6.2 and 1.7 times greater than data supplied to FAO by Mozambique and Tanzania respectively. The reliance on incomplete and substantially under-reported national data puts authorities under serious risk of over-licensing fishing access and mismanaging marine ecosystems and national food security.     

Investigations into the diet and feeding ecology of the bearded goby Sufflogobius bibarbatus off Namibia

The bearded goby Sufflogobius bibarbatus has come to replace sardine Sardinops sagax in the diets of many top predators within the marine environment off Namibia, and it is playing a key role within the region's foodweb. Previously published information on the diet of the bearded goby has been derived from small samples and has been contradictory. We investigated the gut contents of over 3 500 specimens of S. bibarbatus from two separate studies. The results indicate that the species has a fairly generalised diet, feeding mostly on benthic and pelagic animals (phytoplankton was rare), in a way that reflects ontogeny, habitat and likely prey availability. Smaller, more pelagic individuals included a substantial number of pelagic organisms in their diet and the proportion of benthic organisms increased with the size of the goby. Given the importance of this species in recycling benthic carbon through the foodweb of the northern Benguela ecosystem, there is a need to describe and quantify the benthic food environment.     

阿拉斯加北极地区的工程设计和施工经验及教训

阿拉斯加北极地区位于布鲁克斯山以北, 白令海峡以东的北坡地区, 属北极海洋性气候区. 区内寒冷( -10 ～ -6 ℃)、连续多年冻土厚度多在200～300 m, 局部达700 m. 地表湖塘和冰楔多边形广泛分布. 阿拉斯加北极地区的工程建筑活动主要为海军部和商业石油勘探、开发和运输服务. 从20世纪40年代以来, 尽管有不少的曲折和教训, 但成功和可以借鉴的经验很多. 最成功的例子当数普如道湾油气田开发、阿里亚斯卡输油管道工程及其相应的环境保护措施. 工程师为了成功和经济地在北极地区修筑和运行工程设施, 必须从"冷"处着想, 并付诸计划和行动. 设计和施工的工程师必须保持实事求是、不断创新精神, 而不拘泥于中纬度地区的教育、培训, 或行业传统. 从工程勘察、设计到施工阶段, 工程师和从事环境研究的科学家必须密切合作. 工程师需要知道环境参数, 制约因素和可利用的机会; 环境科学家需要知道工程师的施工设计和问题, 理解工程限制条件、设备工作能力, 以及备选方案的经济学问题. 这些相互理解只能在密切合作中形成, 并能创造工程经济效益和奇迹.     

Field report: Exploring the Doonerak fenster of the central Brooks Range,Alaska, USA

Arctic Alaska is a ‘suspect’ terrane that encompasses approximately 20% of Alaska, stretching from the southern Brooks Range all the way to the continental shelves of the Chukchi and Beaufort Seas. Although the origin and subsequent travels of this large crustal fragment are debated among geologists, most researchers agree upon its composite nature and exotic origin. To constrain the early geological history of this terrane, we describe a recent expedition to the Doonerak fenster of the central Brooks Range. This area has long been regarded as a key locality for understanding the structural evolution of the Mesozoic–Cenozoic Brooks Range orogen; however, our target was different: a unique sequence of volcanic and siliciclastic rocks (Apoon assemblage) exposed beneath a profound pre-Mississippian unconformity, which we argue is of key importance to understanding the early Paleozoic tectonic history of northern Alaska and the greater Arctic.     

High-Latitude Springtime Photochemistry. Part I: NOx, PAN and Ozone Relationships

Springtime measurements of NO_x, ozone, PAN,J(NO₂), and other compounds were made near Ny-Ålesund,Svalbard (78°54N, 11°53E), in 1994 and Poker Flat,Alaska (65°08N, 147°29W), in 1995. At Svalbard medianmixing ratios for PAN and NO_x of 237 and 23.7 pptv,respectively, were observed. The median mixing ratios at Poker Flat for PANand NO_x were 79.5 and 85.9 pptv, respectively. These data areused to estimate thermal PAN decomposition using several differentapproaches. At Svalbard PAN decomposition was very small, while at PokerFlat up to 30 pptv/h PAN decomposed. At both sites the NO_x/PANratio increased with temperature between –10 and 20°C implyingthat PAN decomposition is an important NO_x source. In-situozone production was calculated from the measured NO, NO₂,O₃, J(NO₂), and temperature data, using thesteady state assumption Median ozone production was 605 pptv/h at PokerFlat, and one order of magnitude smaller at Svalbard during the daytime.Only at Poker Flat could a direct influence on the diurnal ozone cycle beobserved from in-situ production. These results imply that PAN decompositionis a major source of NO_x in the high latitude troposphere, andthat this contributes to the observed spring maximum in surface ozone.     

Structure and dynamics of fisheries in Nigeria

The changes that have taken place in Nigerian fisheries are reviewed. Artisanal fishery has continued to dominate the fisheries,contributing over 85% of total fish production. The inland water and coastal seas are fully exploited and the increase in fishery production is not likely. Aquaculture potentials remain untapped as much as deep-sea fisheries. The combined potential of the fisheries resources-freshwater,marine and aquaculture can meet over 90% of the nation's demand for fish. Opportunities for invest-ments,therefore,exist in the various subsectors,especially in the areas of storage,processing and preservation for the capture fishery and fish seed multiplication for aquaculture.     

中国海洋渔业碳平衡状态及影响因素研究

低碳是海洋循环经济实现的重要途径,实现海洋渔业的碳平衡是海洋传统经济转变的重要发展方式。本文通过对2013—2022年全国及沿海9省(区)的海洋捕捞碳排放量与碳汇量测算,在此基础上分析了全国及沿海9省(区)的碳平衡状态,并利用灰色关联度分析碳平衡状态影响因素的关联度。结果表明除2020年-2022年山东省的碳平衡状态为盈余外,其他均为碳赤字状态。对于碳平衡状态的影响因素,总体来看全国与沿海9省(区)关联度较大的是海洋捕捞产量、捕捞人员数量和海水养殖面积。最后从加快渔船的升级改造与更新淘汰、调整捕捞的作业方式、提高海水养殖贝藻类的养殖规模以及加快渔业专业合作组织的建立和加速推广渔业碳汇交易提出相关对策建议,以期尽快地实现海洋渔业的碳平衡。     

产业链视角下中国海洋渔业高质量发展水平综合评价

产业链建设是产业高质量发展主阵地,提升海洋渔业产业链现代化水平是支撑海洋经济高质量发展的必要条件。为进一步提升海洋渔业区域产业链联动水平,深入推进海洋经济转型升级,本文基于产业链多维内涵,从创新链、价值链、供应链、空间链四个维度出发,构建海洋渔业高质量发展水平评价指标体系;运用逼近理想解排序法（TOPSIS）、对抗解释结构模型（AISM） 和障碍度模型,对2006－2020年中国沿海11个省（区、市） 海洋渔业高质量发展水平及其影响因素进行分析,并提出相应建议措施。结果表明：（1） 时间上,研究期内中国海洋渔业高质量发展水平逐年向好,各维度贴近度数值均呈现不同程度波动上升趋势,其中创新链维度贴近度数值较高且稳定增长,价值链和空间链维度贴近度数值增长较快,供应链维度贴近度数值还有较大提升空间。（2） 空间上,中国海洋渔业高质量发展水平区域差异较大,在四大维度中优势和劣势各不相同。（3） 优劣层级划分上,研究区海洋渔业高质量发展水平总体层级较为明显,其中山东表现最好,河北和海南较差,除江苏、上海、广西三个活动要素外,其他地区发展稳定,呈刚性结构。（4） 影响因素上,创新链水平对海洋渔业高质量发展阻碍最大,价值链水平和供应链水平也有一定影响,研究期内第一障碍因子分别是X1水产技术推广经费、X5水产技术推广机构技术成果数量和X3渔民技术培训期数。产业链视角下研究海洋渔业高质量发展可促进现代渔业体系向信息化、智慧化发展,助推经济、社会高质量发展。