Status of giant clam resources around Okinawa‐jima Island,Ryukyu Archipelago,Japan

1. Giant clams provide and support valuable functions to coral reefs, as well as represent a sustainable resource for traditional fisheries throughout the Indo‐Pacific region. The Ryukyu Archipelago (southern Japan) is known to be the northern latitudinal limits of giant clam distribution, but there is only limited information in the literature regarding species diversity, status, and distribution in this region.
2. In this study, we report findings from a rapid survey in 2016, the first of its kind for the Ryukyu Islands, to determine species distribution and abundance of giant clams (tridacnines) around Okinawa‐jima Island.
3. Results indicate the presence of four species with an overall density of 5.03 per 100 m², from most to least abundant: Tridacna crocea, Tridacna maxima, Tridacna squamosa, and Tridacna noae. The previously reported species Tridacna gigas and Hippopus hippopus were both absent from the surveys. The densities and distributions of tridacnines varied among species and sites, which are likely attributable to efforts in replenishing and protecting stocks of selected species.
4. The most abundant species, T. crocea, is an important fishery species in Okinawa, and has been widely cultured and restocked to augment depleted populations. In comparison, restocking efforts for less popular species, such as T. squamosa, have been limited, and their current sizes and numbers suggest recruitment constraints.
5. Given the importance of the giant clam fishery in this region and the current declines of various species (except T. crocea), further regulations should focus on the protection of larger and mature clams that function as broodstock necessary to maintain spawning and natural recruitment.

     

Using fishers’ ecological knowledge to assess the status and cultural importance of sawfish in Guinea‐Bissau

1. Sawfishes have declined dramatically in West Africa and may be extinct throughout much of their historical range. Guinea‐Bissau is considered to be one of the last remaining places in West Africa where sawfish persist.
2. Fishers’ ecological knowledge (FEK) can provide valuable baseline data, which can be used to direct scientific studies, in situations where information is scarce or lacking and can also provide insight into local attitudes towards species of interest. Interview surveys were used to collect FEK data on the past and current range of sawfishes within Guinea‐Bissau waters, perceived causes of the decline amongst fishermen, and the cultural importance of this species to Bissau‐Guineans.
3. Data were collected from 274 respondents, of whom 85% could identify a sawfish from an image. The majority of respondents reported to have last seen a sawfish in the 1980s, although this varied considerably by region, and 30% of respondents in the south had seen or captured sawfishes in the past decade up to and including 2012.
4. Overfishing or excessive fishing pressure was most frequently cited as a perceived cause for the decline in sawfish, followed by shark finning and overseas fishermen. The sawfish is primarily of cultural importance in the Bijagos Islands, where it is central to many traditional ceremonies.
5. This information provides valuable insight into the cultural importance of sawfish to Bissau‐Guineans and their concerns in relation to the sustainability of their local fishery resources. Information on recent catches will be useful for directing future work to locate and protect remaining sawfish in Guinea‐Bissau.

Copyright © 2013 John Wiley & Sons, Ltd.     

Pueruli of Panulirus longipes bispinosus (Crustacea, Decapoda, Palinuridae) stranded on the beach of Kuroshima Island, Ryukyu Archipelago, southern Japan

ABSTRACT: Stranded organisms were observed on the sandy beach of Kuroshima Island, Ryukyu Archipelago, in the early morning of 28 January 1993. Stranded organisms of 525 individuals were classified into 74 species. These organisms included 13 individuals of Panulirus pueruli, which were identical to P. longipes bispinosus. Kuroshima Island is located near Ishigakijima and Iriomote islands, Ryukyu Archipelago, where coral reefs develop. Coral reefs are common and develop in the Ryukyu Archipelago, southern Japan, with the exception of Yakushima and Tanegashima islands. Panulirus japonicus in Japanese waters has not been found in coral reef regions where P. longipes bispinosus are mainly found. The present study describes and identifies to species level puerulus specimens that were stranded on the beach of Kuroshima Island.     

舟山海岛野生观赏植物的应用

通过对舟山群岛植物资源的调查研究,分析了耐盐碱植物、耐干旱瘠薄的阳性植物、耐阴植物和彩叶植物等海岛野生观赏植物的资源种类和特点,论述它们在营建沙滩风景林、海岛植物群落及园林绿化中的应用前景和方法.针对目前舟山海岛野生观赏植物开发应用不足,缺乏地方特色等现状,提出了合理开发野生观赏植物,筛选沙滩风景林树种和规划营造海岛群落景观等方面的建议,特别强调应采用海岛特色植物以体现海岛城市风格.参10     

马鞍列岛海洋特别保护区斑头六线鱼的摄食习性

为了解马鞍列岛海洋特别保护区岩礁生境斑头六线鱼的摄食习性,基于2009年3月~2010年2月多网目组合刺网调查获取的252尾斑头六线鱼样本,研究了斑头六线鱼的饵料组成和摄食策略。结果表明斑头六线鱼主要摄食端足类的麦秆虫,是以麦秆虫为主食的狭食性鱼类。斑头六线鱼摄食种类随季节变化,春季、夏季和秋季主要摄食端足类,表现为狭食性的摄食特性,冬季主要摄食蟹类、腹足类和其他类,表现为广食性的摄食特性。     

舟山海岛普陀樟等3种特有树种种质资源清查

通过清查,发现普陀樟Cinnamomum japonicum var. chenii集中分布于舟山市普陀区所辖范围内的洛伽山、朱家尖岛以及以朱家尖、桃花、六横岛为中心的毗邻悬水小岛上,种质资源比较丰富,全市共有结果母树1.2万余株,大年种子产量有1500 kg左右。舟山新木姜子Neolitsea sericea分布在普陀区的朱家尖、桃花、普陀山和定海区的大猫岛,其分布特点是孤立,散生,且范围极小,无成片分布,共有结果母树300余株,种质资源较为贫乏,加之不合理的采种,迄今大年种子产量仅为100 kg。南京椴Tilia miqueliana分布范围更是有限,主要分布在桃花岛蚂蝗坑和定海区大猫岛茅草屋冷坑,呈群落分布,共有结果母树170余株,每年种子产量极少,能采到的种子只有0.25 kg左右。表3参12     

The conservation status of Townsend's shearwater Puffinus auricularis auricularis

Townsend's shearwater (Puffinus auricularis auricularis) is an endangered seabird endemic to the Revillagigedo Archipelago. It nested on Socorro, Clarion, and San Benedicto Islands. It was extirpated by the Barcena volcano on San Benedicto in 1952, and there are no recent indications of nesting. Introduced mammals—pigs and rabbits—preyed on them and destroyed habitat at Clarion; shearwaters were extirpated by 1988, and no breeding attempts have been reported since. Our results confirm that Socorro holds the last breeding grounds. We found breeding colonies above 800 m and a minimum population of 1100 individuals. This represents a significant reduction in distribution and population size. Intensive cat predation at Socorro could potentially kill ca. 350 females per season, and sheep progressively destroy nesting areas. Population projections suggest that demographic instability could occur in less than 100 years under severe predation and habitat degradation. Only low predation rates would allow population persistence for more than 150 years in spite of a declining population. Thus, the immediate eradication of all introduced mammals is necessary to prevent the extinction of this seabird.     

Comparisons of age,growth, and maturity between male and female,and diploid and triploid individuals in Carassius auratus from Okinawa‐jima Island,Japan

• 1. Carassius auratus, a primary freshwater fish with bisexual diploid and unisexual gynogenetic triploid lineages, is distributed widely in and around the Eurasian continent and is especially common in East Asia. East Asian C. auratus diverged genetically to form local endemic populations in different regions, and those distributed in the Ryukyu Archipelago form a local endemic population that can be regarded as an evolutionarily significant unit because of its high phylogenetic independence and evolutionary distinctiveness. Although the evolutionary uniqueness of this population should be conserved, its distribution area and population size are decreasing rapidly, and some island populations are currently considered endangered or already extinct.
• 2. To develop effective conservation measures to stop the current decline of Ryukyuan C. auratus, ecological data need to be collected. In this study, life history data for a C. auratus population distributed in the Hiji River system were collected by estimating age, growth, and spawning season.
• 3. The spawning season of C. auratus in the Hiji River extended from March to September, peaking during March–May. Females became sexually mature in their second year, but males reached maturity and were able to spawn as early as in the late spawning season of their year of hatching. Once having reached sexual maturity, males probably continuously stay ripe throughout their life.
• 4. Sagittal otoliths of C. auratus proved to be useful ageing structures because one annual increment is formed on the sagittal otolith before the spawning season in each year. The oldest fish observed were a 10‐year‐old female and an 11‐year‐old male. Females showed faster somatic growth and higher final standard length than males, and a sexual size dimorphism was observed.
• 5. The standard length at each age class did not differ between diploid and triploid C. auratus, suggesting that triploid growth rates were almost equal to those of diploids. Copyright © 2009 John Wiley & Sons, Ltd.

     

Chagos feels the pinch: assessment of holothurian (sea cucumber) abundance,illegal harvesting and conservation prospects in British Indian Ocean Territory

• 1. Data are analysed from visual censuses of shallow‐water holothurians (sea cucumbers) in 72 shallow water transects 100 m×2 m within four atolls of Chagos. Mean holothurian abundance in Diego Garcia, where harvesting is absent, was 18.5 individuals/transect (all transects) and 55.4 individuals/transect (only those containing holothurians). In the three exploited atolls, mean abundance did not exceed 3.5 and 5.2 individuals/transect, respectively.
• 2. Comparison with data collected during this study and an earlier investigation reveals a marked decline over four years in both mean and maximum density of commercially valuable Stichopus chloronotus and Holothuria atra in Salomon and Peros Banhos, both exploited atolls, and also for Holothuria nobilis in the latter.
• 3. Holothurian counts were also made along an extensive transect (21 km×4 m) encircling Salomon atoll. Abundance showed highly significant negative correlation with fishing pressure, the latter estimated using an ordinal (0–3) scale (R_s=?0.605, P?0.01). Harvesting effects were not discernible using data from 200 m² transects.
• 4. While recent studies have shown Chagos is virtually pristine regarding contaminant levels, its holothurian resources are under increasing pressure. Results from this study, and examination of Sri Lanka's fishing activity in distant waters, point to heavy and illegal harvesting.
• 5. Stronger measures are needed to control the illegal fishery, to prevent holothurian abundances falling to the non‐sustainable levels now prevalent across much of the Indo‐Pacific, and to ensure that Chagos remains a biodiversity hotspot and environment of international renown. Use of smaller surveillance vessels would facilitate this.Copyright © 2009 John Wiley & Sons, Ltd.

     

洞头县古树资源概况及保护复壮意见

洞头县现有古树81株，属热带、亚热带、暖温带树种，且以桑科植物数量多，其次是榆科、金缕梅科、杜英科植物。古树分布面广、数量少，久经风霜、病虫害、台风、雷击、雨雪、立地条件恶化及人为破坏等因素均加速古树的衰败，为此，提出严加保护、制订保护管理条例、修理美化、改良土壤等措施。