Quantifying the relative intensity of fishing on New Zealand seamounts

New Zealand seamounts support major fisheries for several deepwater fish species, including orange roughy (Hoplostethus atlanticus) and smooth oreo (Pseudocyttus maculatus). Although a high proportion of features in the depth range 500–1000 m have been fished, very little is known about the ecological impacts of bottom trawling on seamounts. The potential impact is likely to be influenced by the spatial extent and frequency of fishing. A new index is presented to assess the relative intensity of trawling on New Zealand seamounts. The fishing effects index (FEI) incorporates information on the density of fishing on the seamount as a proportion of the seabed area and also on tow direction. Detailed fisheries data from more than 250 000 tows were examined to calculate FEI for New Zealand seamounts. The most intensively fished seamounts were on the south Chatham Rise, an area characterised by a large number of relatively small features which were fished serially for orange roughy in the 1980s and 1990s. Other seamounts with high FEI were on the north Chatham Rise, Challenger Plateau, and off the east coast of the North Island. A range of sensitivity analyses indicated that the general rankings of seamounts were relatively robust to the choice of arbitrary thresholds used to assign tows to seamounts.     

生物技术清洁生产替代高污染化学法制备甲壳素的研究与应用

从虾壳中分离到一株乳杆菌BR-3,研究发现其最佳发酵起始pH为6.50,最佳培养温度为35℃,在此培养温度下达到对数生长期的时间为42h。采用乳杆菌发酵方法,进行了虾壳制备甲壳素的研究,比较了接种量、葡萄糖加入量、发酵时间等因素对产品质量的影响。结果表明,当接种量为10%、葡萄糖浓度为4.5%、固液比为1︰3、发酵温度为(35±2)℃、发酵时间为3—4d时,平均灰分去除率达95.67%,甲壳素产品灰分含量均小于6%,最低可达1%,产品质量等于或优于传统的酸碱生产方法。发酵液可部分或全部回收,洗涤废水可作下一轮发酵用水,生产废水接近零排放。虾壳乳酸发酵法生产甲壳素是一种清洁生产方法。BR-3培养时间短,培养条件粗放,温度和pH适应范围宽,产酸效率高,残糖少,适合于工业化生产。     

虾池小型底栖动物的数量研究

提出１９８７年５月至１０月在黄岛养虾池对虾生长周期内对小型底栖动物数量逐月调查。指出：小型底栖动物总平均密度为１０９２．４ｉｎｄｓ·１０ｃｍ－２，自由生活海洋线虫和底栖桡足类是主要类群，其总平均密度分别为４６６．９和４５７．９ｉｎｄｓ·１０ｃｍ－２。８９．７％的小型底栖动物分布在沉积物表层２ｃｍ内。结果指明小型底栖动物被对虾捕食，并提出了捕食模式。     

Trawling or Visual Censuses? Methodological Bias in the Assessment of Fish Populations in Seagrass Beds

Abstract. Fishes associated with the seagrass Posidonia oceanica were censused both by skid trawl and visual counts around Ischia Island, Italy. Both sampling procedures were performed during the day in summer and in winter at two sites. Significant differences in the number of species, number of individuals, biomass, and trophic structure of the fish assemblage were observed between sampling methods. Fewer fish species were recorded by visual counts than by trawling. More individuals and a greater biomass, however, were recorded from visual counts. The population of macrocarnivores (Scorpaenidae, Serranidae) were better estimated by trawling, as were canopy-dwellers (Syngnathidae; Symphodus rostratus) and benthic species (Gobiidae; Blenniidae; Bothidae). Conversely, good swimmers ( Sparidae; Coris julis, Symphodus spp.), and planktivorous fishes (Centracanthidae, Pomacentridae) mostly escaped the trawl and were better assessed by visual counts. The importance of methodological biases differed from one season to the other and was higher in summer than in winter. Particular attention should be paid to the biases induced by sampling techniques when interpreting data, and different sampling methods should be used to accurately study the fish assemblages of seagrass meadows.     

用于倍性检测的对虾样品的保存方法

采用9种保存方法分2个温度梯度,对待测倍性的日本对虾幼体样品进行处理,通过对利用流式细胞仪检测的不同样品直方图进行比较,筛选出一种较为理想的用于倍性检测的对虾样品的保存方法。结果表明：新鲜样品在分散液中捣碎,加入一定量的二甲基亚砜(DMSD)后可在-20℃下保存较长时间。     

酶法制备低盐虾酱的研究

为了解决传统的自然发酵工艺制备虾酱带来的种种弊端,本选用小型毛虾经蛋白酶水解,采用甲醛滴定法对不同加酶量、酶解时间、温度和用盐量对FAM值的影响进行了测定,确定了碱性蛋白酶和中性蛋白酶的最适反应条件均为加酶量0.5％,酶解温度55℃,加盐量18％,而最适酶解时间分别为2h和1h,最适pH为7.0。酶法制备低盐虾酱使产品低盐,适合大众消费;高温酶解,风味品质更好;生产周期短,降低所需成本。酶解后毛虾的产品质量符合国家卫生标准。     

Relative importance of dissolved and food pathways for lead contamination in shrimp

The relative importance of dissolved and food pathways and the influence of food type in the bioaccumulation and retention of lead in the shrimp Palaemonetes varians were examined using a radiotracer method. Shrimp were exposed to ²¹⁰Pb-labelled seawater or fed two types of ²¹⁰Pb-labelled food, viz. mussels or worms. The amount of radiotracer accumulated by shrimp was examined over a 7-day period, followed by a 1-month and a 7-day depuration period for the dissolved and food source, respectively. Steady state in the uptake was reached after 2 days exposure to dissolved lead, with a resultant estimated concentration factor of 98 ± 3. Transfer factors following ingestion of contaminated mussels and worms were lower than unity for both food types, with lead transfer from worms being significantly higher than that from mussels. Accumulation of dissolved Pb by shrimp was found to occur mainly through adsorption on the exoskeleton with a minor accumulation in the internal tissues probably resulting from the intake of seawater for osmoregulation. In contrast, lead taken up from contaminated food was readily absorbed and bound in the internal tissues of P. varians. Although the transfer of lead to P. varians through the ingestion of contaminated food was low (TF < 1%), it still represented 4 to 8% of the lead content in the prey which is a significant additional contribution of lead to the shrimp body burden. Independent of food type, following ingestion of contaminated food, approximately 23–27% of total lead accumulated in shrimp was located in the edible parts (e.g. muscle). Therefore, the food pathway is suggested to be a significant contributor to the lead transfer to humans through ingestion of contaminated shrimp. After exposure to contaminated food, lead loss kinetics were described by a two-component model, whereas Pb loss following direct uptake from seawater was best described by a three-component model. The additional compartment representing 64% of total Pb retained and characterized by a turnover < 10 min, corresponded to lead weakly adsorbed on the exoskeleton and incorporated in the hepatopancreas. Nevertheless, a significant fraction of lead accumulated from the dissolved (2%) and food (52–57%) pathways remained irreversibly retained in the tissues, suggesting that this organism could also serve as an effective long-term bioindicator of lead contamination in marine waters.     

Stock size matters more than vessel size: The fuel efficiency of Swedish demersal trawl fisheries 2002–2010

Fisheries management determines how much of each stock can be landed when, where and how fishing is permitted. It has been identified to strongly influence the environmental performance of the fishing industry, including fuel use. As fuel data for fisheries is scarce, especially on a detailed level, the aim of this study was to develop an approach for utilizing fleet-wide fuel data to estimate the fuel use of individual fisheries and mapping how fuel efficiency in Swedish fisheries is influenced by management. Swedish demersal trawl fisheries were studied between 2002 and 2010. Results show that the overall fuel efficiency has improved and interesting patterns between different fisheries and vessel sizes emerged. The difference in fuel efficiency per kilo landing between large and small trawlers was generally small, unless catch capacity was lowered e.g. by selective grids. Stock rebuilding was shown to be highly important for fuel efficiency, as fuel use was inversely correlated to the biomass of eastern Baltic cod. However, rebuilding can also lead to trade-offs e.g. in the case of selective trawling, where protection of depleted stocks comes at the cost of higher fuel intensity per landing. Finally, tax exemption of fuel use in fisheries was shown to maintain inefficient fisheries. These results could be used to reduce overall environmental impacts of fishing further by incorporating fuel use as an additional aspect into the fisheries management system.     

Tagging experiments on trawl‐caught trevally,Caranx georgianus,off north‐east New Zealand, 1973–79

A total of 2676 trevally, Caranx georgianus Cuvier, was tagged in the Hauraki Gulf and Bay of Plenty during 1973 and 1974. Fish were caught by research trawler, anaesthetised, and tagged with spaghetti tags. During the following 5 years, 130 tags (4.9%) were returned. Most recaptures came from set nets (42%), followed by commercial trawlers (22%), Danish seiners (11%), research trawl (9%), other methods (7%), and method unknown (9%). Excluding tagged fish taken by research trawl, 85% of tag returns were made by commercial fishermen and 15% by amateurs. Initial tagging mortality was low, but was probably significant over an extended period. Movements of trevally were limited; 88% moved less than 30 nautical miles (55 km) from the release site. However, there was sufficient movement to regard trevally from the Bay of Plenty and probably also the Hauraki Gulf as one stock.