Movements and behaviors of swordfish in the Atlantic and Pacific Oceans examined using pop‐up satellite archival tags

Swordfish are highly specialized top‐level predators that have been challenging to study. In this paper, data from 31 pop‐up satellite archival tags attached to swordfish from (i) the eastern Pacific, (ii) central Pacific, and (iii) western North Atlantic‐Caribbean were analyzed. Common across locations was a pronounced diel vertical pattern with daytime hours spent primarily below the thermocline and nighttime hours spent in warmer waters, close to the surface. One exception to this pattern was periodic daytime basking events which were most common in cooler waters off California. Maximum daytime depths were significantly correlated with light penetration as measured by the diffuse attenuation coefficient at 490 nm. Temperature did not appear to influence daytime depths, and swordfish tolerated both extremely low temperatures (4°C) and rapid and dramatic temperature changes (>20°C). Temperature did appear to influence the nighttime depths in the Pacific where fish typically remained in the surface mixed layer. In contrast, in the warm tropical Atlantic this was not the case, and nighttime depths were much deeper. In all areas, nighttime depth increased around the full moon. Given the parallels between the vertical movement patterns of swordfish and those of the deep sound scattering layer we suggest that swordfish vertical distribution patterns, especially during daytime, are influenced largely by resource availability. At night, when swordfish are typically targeted by fisheries, both ambient light and temperature influence movements. Understanding vertical movement patterns of swordfish can help evaluate gear vulnerability, improve population assessments, and potentially reduce fisheries bycatch.     

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.     

不同气候模态下西北太平洋柔鱼渔场环境特征分析

柔鱼冬春生群体广泛分布于西北太平洋,其种群分布与大小受气候变化和环境因子调控。本实验根据中国鱿钓组提供的1995—2011年渔业捕捞数据和海洋环境数据包括海表温度(SSTA)、海表面高度(SSHA)和混合层深度(MLDA)的距平值,分析不同气候模态下(PDO暖期和PDO冷期)柔鱼渔场环境的变化。结果显示,PDO暖期时,柔鱼CPUE高;PDO冷期时,CPUE变低。柔鱼渔场SSTA、SSHA和MLDA年间变化显著,各环境变量的时间变化与PDO冷暖相位对应。SSTA和SSHA与PDO指数负相关,滞后时间分别为–9~10月和–20~17月,且均在0月时相关系数最大;而MLDA与PDO指数呈正相关,滞后时间为–6~5月,在–1月相关系数最大。利用经验正交函数分析了SSTA、SSHA和MLDA时空变化的主要模态,前5个模态特征向量分别反映了西北太平洋柔鱼渔场SSTA、SSHA和MLDA分布场78.73%、32.82%和64.57%的信息。研究表明,气候模态变化驱动柔鱼渔场环境的变化,进而对西北太平洋柔鱼资源丰度产生显著影响。     

近30年渤海鱼类种群早期补充群体群聚特性和结构更替

基于30余年渤海鱼卵、仔稚鱼历史调查资料的整理分析并结合产卵场补充调查,以1982~1983年周年逐月调查资料为本底,采用多元统计学方法分析30余年渤海鱼类种群早期补充群体群聚特性(物种多样性和关键种群)的季节变化和年代际变化,并掌握结构更替过程中优势种和重要种协同消长规律。分析结果显示,渤海各调查季节(冬季除外)鱼卵、仔稚鱼种类数以及资源丰度指数呈先降后升变动趋势。当前鱼卵种类数仅为20世纪80年代1/2左右,资源丰度不足20世纪80年代的1/10;仔稚鱼种类数和资源丰度仅为20世纪80年代的3/4左右,但冬季仔稚鱼种类数和资源丰度指数呈现上升趋势。各调查时期相同季节鱼卵优势种变化不明显,但仔稚鱼优势种变化幅度超过鱼卵,底层重要经济种类早期补充群体优势度急剧下降;鱼卵和仔稚鱼物种多样性水平在升温季节较高而在降温季节较低,调查期内各季主要呈现先降后升变动趋势。鱼类早期补充群体种类更替现象明显,近年来种类更替率呈现明显加快趋势。各调查时期相同季节各适温类型产卵亲体种数均呈现先降后升变动趋势,但各适温类型种数所占比例和全年综合各适温类型种数所占比例基本稳定。各调查时期相同季节各主要栖所类型产卵亲体种类数也均呈现先降后升变动趋势,全年综合陆架浅水中上层鱼类种数所占比例升高,中底层和底层鱼类所占比例有所下降。近30年在多重外来干扰作用下,渤海鱼类早期补充过程各个关键环节已随其栖息地(产卵场)生境要素发生不可逆变化或变迁。渤海鱼类种群早期补充群体群聚特性和结构更替是环境-捕捞胁迫下鱼类群落内多重生态位的交替失调和渔业资源结构性衰退的具体表现。     

The Potential for the Restoration of Marine Ornamental Fish Populations Through Hatchery Releases

Populations of tropical and subtropical marine fish are being depleted worldwide to supply increasing demands of the aquarium industry and fresh seafood market. Overfishing and destructive harvest techniques have left some marine fish populations virtually extirpated in a number of primarily underdeveloped countries. In situations where only small remnant populations and significantly degraded habitat remain, population recovery even under the complete absence of collection will be slow, with the high potential for population loss due to natural environmental and recruitment variability. Stock enhancement, supplementing natural recruitment with hatchery produced fry, has the potential to significantly increase the rate of population recovery while maintaining population vigor.Stock enhancement research on Pacific threadfin has demonstrated measurable positive impacts on recreational and commercial fisheries for this species in experimental scale releases; similar successes can be expected for enhancement efforts directed toward species of ornamental value. The major technological barrier to ornamental fish enhancement, the development of appropriate culture capabilities, is being addressed in research directed to the commercial production of fish for the aquarium trade.     

Histopathology of Hematopoietic Tissue in Channel Catfish,Ictalurus punctatus,with Anemia

Outbreaks of anemia (CCA) in channel catfish, Ictalurirs punctatus, in Mississippi occur predominantly during spring and fall. Between October, 1990 and May, 1991, twenty-seven cases of CCA were submitted to the Mississippi Cooperative Extension Service-College of Veterinary Medicine Fish Diagnostic Laboratories. Histologic lesions were identified in the head and trunk kidneys of all affected fish. The head kidney contained less than 25% immature hematopoietic tissue in 3 of 22 cases (14%). 25-50% immature hematopoietic tissue in 7 of 22 cases (32%), and greater than 50% immature hematopoietic tissue in 12 of 22 cases (54%). The trunk kidney contained less than 25% immature hematopoietic tissue in 5 of 27 cases (18%), 25-50% immature hematopoietic tissue in 15 of 27 cases (56%), and greater than 50% immature hematopoietic tissue in 7 of 27 cases (26%). The histopathologic findings noted in cases of CCA from Mississippi affect primarily the hematopietic tissues of the head and trunk kidneys.     

Reviews

Books reviewed: H.W. Arndt and Hal Hill (eds), Southeast Asia’s economic crisis: Origins, lessons and the way forward William Cline, Trade and income distribution Morris Goldstein, The Asian financial crisis: Causes, curses and systemic implications Lamont Lindstrom and James Gwero (eds), Big Wok: Storian blong Wol Wo Tu long Vanuatu     

Interannual variation in the availability and utilization of euphausiids as prey for Pacific hake (Merluccius productus) along the south-west coast of Vancouver Island

The species and size composition of euphausiids consumed by Pacific hake ( Merluccius productus ) along the south-west coast of Vancouver Island were monitored during the 1989, 1990 and 1995–97 summer feeding seasons. Thysanoessa spinifera and Euphausia pacifica were the only euphausiid species eaten by hake. Hake persisted in selecting krill longer than 17 mm and consistently preferred T. spinifera, even though there was a substantial reduction in euphausiid abundance, a change in species composition and a shift in the size distribution to smaller individuals after the 1992–93 warm water years. The biomass of euphausiids available to hake after 1993 averaged 27% of that for 1991, the pre-ENSO year, and was 12% of the 1991 value in 1996. Hake predation was not responsible for the reduction in euphausiid abundance, as it was already low at euphausiid sizes smaller than those eaten by hake.     

Potential futures for road transportation CO2 emissions in the Asia Pacific

Abstract: Will future transportation carbon dioxide (CO₂) emissions per capita in Asia Pacific economies follow historical trends of the now developed world? Evidence to date is inconclusive. A comparison at similar income levels (purchasing power parity) between recent emissions in Asia Pacific countries and historical emissions in developed countries suggests diverging patterns. (A) High‐income Asia economies (Japan, Hong Kong and Singapore –‘low emitters’) exhibit lower emissions than a selected sample of seven developed countries (United States, Australia, France, the Netherlands, Italy, Sweden and United Kingdom). (B) Another set of Asian countries (South Korea and Taiwan –‘medium emitters’) follow the emissions trends of European countries, which are lower than those of Australia and the United States. (C) A third Asian group (Malaysia and Thailand –‘high emitters’) exhibit emission trends comparable to that of Australia. We describe these trends, examine their causes and extrapolate likely futures for emissions in low‐income Asia Pacific economies (China, Indonesia, Philippines and Vietnam). Although such predictions are speculative, the available evidence suggests that road CO₂ emissions for Indonesia, the Philippines and Vietnam will follow those of the third group (high emitters), while those for China may follow either Group B or Group C.     

Agroforestry in the management of sloping lands in Asia and the Pacific

Steeply sloping lands are widespread in the tropics. An estimated 500 million people practice subsistence agriculture in these marginal areas. Continued population growth has led to the intensified cultivation of large areas of the sloping lands, exacerbating the problem of soil erosion. Although research shows that alley cropping and other contour agroforestry systems can stabilize the sloping lands, these systems have not been widely adopted by farmers. The Framework for Evaluating Sustainable Land Management (FESLM) has been tested in sloping land areas in the Philippines. Sustainable land management must be productive, stable, viable, and acceptable to farmers, while protecting soil and water resources. Farms on which contour hedgerow intercropping has been adopted meet the multifaceted requirements of FESLM, whereas the farmers' current practice does not. Appropriate land management measures for particular locations depend on a complex suite of social, economic, and biophysical factors, and need to be developed in participation with farmers. The role of agroforestry in sustainable management of sloping lands is the subject of networks coordinated by the International Board for Soil Research and Management (IBSRAM) in seven countries in Asia (ASIALAND) and four countries in the Pacific (PACIFICLAND). We review selected outcomes from a wealth of network data. From these results the following conclusions about the sustainability of various agroforestry systems for sloping lands can be drawn: • In the Pacific, soil loss from sloping lands due to water erosion under farmers' current practices is episodic, unpredictable, and possibly not severe; • Agroforestry systems that utilize legume shrubs, fruit trees, coffee (Coffea spp.) or rubber (Hevea brasiliensis) provide useful economic returns, but are not an essential component in terms of soil protection because grass or pineapple (Ananas comosus) planted on the contour are equally effective in reducing erosion; • Agricultural intensification will lead to nutrient mining, reduction of aboveground biomass, declining yields, and less soil protection unless external sources of nutrients are used; • nitrogen can be effectively supplied using legumes; • Cash derived from hedgerow trees and/or shrubs may providean incentive for their adoption by farmers, as well as funds to purchase external inputs such as fertilizers; • Labor may be a major constraint to the adoption of complex agroforestry systems. We also discuss the information management systems required to effectively manage and utilize the extensive sets of experimental and indigenous data being accumulated. We believe such information systems can facilitate technology transfer across and between regions, and improve the efficiency of research into agroforestry and other land-management approaches. This revised version was published online in June 2006 with corrections to the Cover Date.