The ‘pole-hooking’ method: A novel and economical technique for in situ tagging small to medium-sized fishes

We describe a new manual procedure for catching and tagging fish underwater, the ‘pole-hooking’ method, and demonstrate and discuss its advantages over standard tagging techniques (i.e. hook-and-line fishing). The new technique was designed for tagging Acanthistius brasilianus [Cuvier, M., Valenciennes, L.B., 1828. Histoire Naturelle des Poissons. Museau de Histoire Naturelle, Paris], a small to medium-sized fish inhabiting rocky reefs of the Argentine coast. The pole-hooking method minimizes injuries, avoids fast depressurization of fish and allows registration of the precise location of capture and release. In addition, the equipment needed is very simple and economical. The mean number of fish tagged per minute using this methodology on shallow rocky reefs (up to 25-m depth) was similar to that obtained during hook-and-line fishing sessions (ca. one tagged fish every 3 min), given similar densities of A. brasilianus in the fished reefs.     

Classification of guppies’ (Poecilia reticulata) gender by computer vision

Labor costs of guppy growers and breeders are largely those of manual sorting (by strain, quality and gender) and counting fish. In most farms, female and male fish are grown together and sold either separately or together. Sorting fish according to gender is important for marketing as well as for breeding programs, so that a device for sorting and counting fish can potentially reduce production costs and improve quality.

A project aiming to develop sorting and counting technologies for ornamental fish growers included development and testing of image-processing algorithms for sorting guppy fish (Poecilia reticulata) by gender. The algorithms are derived from shape and color differences between female and male guppies. An algorithm for the determination of landmarks on fish contours was developed and found to be accurate in accordance with human judgment, enabling extraction of specific shape and color features of the tail and the body.

The algorithms were applied to three sets of images of guppies of the “Red-Blond” strain. Gender identification accuracy was approximately 90% using shape features, approximately 96% using color features and was slightly improved when both color and shape features were used.

Some of the components used are essential for future development of a computer vision based system for sorting and grading ornamental fish by strain and quality.     

Spatial integration of freshwater fish markets in the Northern Baltic Sea area

Freshwater fish species and Baltic salmon (Salmo salar) are important to small-scale fisheries in Finland and Sweden. The formerly local markets for these species have expanded as trade has been opened up to international competition. In this study we use cointegration analysis to test the spatial integration of freshwater fish markets in Finland and between Finland and Sweden. The analysed fish species are salmon, perch (Perca fluviatilis), pikeperch (Sander lucioperca), European whitefish (Goregonus lavaretus) and pike (Exos lucius), and the data covers ex-vessel prices from 1993 or 1995 to 2004. We found that the regional prices in Finland were cointegrated. This indicates that the prices are determined on a single market in Finland. Moreover, the study suggests that Finnish and Swedish markets in Baltic salmon, whitefish, pikeperch and perch were partially integrated, while integration of pike markets could not be found. The political implication is that an essential part of the local small-scale fisheries’ operational environment is determined outside the national borders.     

Allometric and ontogenetic patterns related to feeding of a neotropical fish, Satanoperca pappaterra (Perciformes, Cichlidae)

Abstract –  This study aims to analyse whether Satanoperca pappaterra changes its feeding habit throughout ontogenetic development, and whether morphological ontogenetic patterns are related to its feeding habit and food capture. We collected 258 individuals in the Cuiabá river basin (Brazil) for analyses. There was a weak relationship between diet and body size, as evidenced by size class and multivariate analyses, and niche breadth did not vary strongly during ontogenetic development. Eight morphometric variables were measured in each individual. We found an isometric relationship for mouth height and width, and for head length. We found positive allometry for snout length and body height in relation to body length, whereas this relationship for intestine length and eye diameter showed negative allometry. These results suggest that morphology and consequently diet vary weakly during ontogenetic development of S. pappaterra .     

Reproductive seasonality in a swamp-locked African cichlid

Abstract –  This study quantified the seasonal pattern of reproduction in a swamp-dwelling population of the African cichlid Pseudocrenilabrus multicolor victoriae. In the hypoxic waters of the Lwamunda Swamp, Uganda, P. multicolor was reproductively active throughout the year, even during the peak of the dry seasons. However, the degree of activity was seasonal, with rainfall providing a predictor of the percentage of ripe, mature females. There was no correlation between aquatic oxygen availability dissolved oxygen (DO) and either adjusted mean gonad mass or percentage of mature females, suggesting that DO is not limiting reproductive activity in this system. Reproductively mature females were larger during drier periods and may maximise their lifetime reproductive success by producing young throughout the year; but with a lower brooding efficiency. A comparison with Welcomme's (1969) study of a river-swamp system feeding Lake Victoria suggests that reproductive patterning is variable among populations of P. multicolor and may reflect adaptive response to chronically hypoxic conditions in the Lwamunda Swamp.     

Effects of an extreme flash flood on the native fish assemblages across a Mediterranean catchment

Abstract  The effects of an extreme flash flood on the native fish assemblages across a Mediterranean catchment in Southwest Portugal were investigated. The fish community structure and habitat were surveyed at 10 sites pre- and post-flood. Overall species richness and rank abundances changed little after the flood, despite there being a consistent decline in the abundance of small cyprinids. Pre- and post-flood habitat correlates of abundance changed for at least some species, and variability in assemblage structure was associated with flood, depth and pH. These results indicate that extreme floods occurring early in the wet season may have little disruptive effects on the overall structure of native fish assemblages in Mediterranean streams, although may at least partially influence population dynamics for some species. Habitat quality and complexity are likely to play a role in mediating species responses to flooding.     

鱼类解偶联蛋白（UCP）基因研究新进展

通过生理性解偶联调节氧化磷酸化效率可能是进化早期发展起来的一种普遍策略,对生命的存在至关重要. 解偶联蛋白（uncoupling protein,UCP）家族是位于线粒体内膜的转运蛋白,哺乳动物基因组中已发现5个成员,其中UCP1~UCP3紧密相关,而UCP4和UCP5（即BMCP1,brain mitochondrial carrier protein-1）与它们差异较大. UCP1~UCP4不仅在哺乳类、鸟类等恒温脊椎动物中普遍存在,而且在鱼类等变温动物中也被证实存在,但UCP5目前仅在哺乳类中被发现. 哺乳动物褐色脂肪组织的UCP1,介导呼吸链产生的质子梯度泄漏,使氧化产生的能量以热的形式散发,但鱼类等变温动物UCP1的功能尚待进一步研究确立. UCP2和UCP3在产热、控制活性氧生成、脂肪酸氧化以及肥胖、糖尿病的发生中均发挥重要作用,二者的转录调节较复杂. UCP4和UCP5与其他UCP关系较远,UCP4仅在脑中表达,而UCP5在脑中高表达,它们的功能还不十分明确,但研究表明很可能与UCP2和UCP3的功能相似.     

利生源牌王浆花粉产品中化学成分的含量测定

目的：测定王浆花粉产品中化学成分的含量；方法：采用三氯化铝-醋酸钠比色法，以芦丁作为对照品，测定总黄酮的含量，用药典方法测定水分含量、醚提物含量、醇提物含量；结果：王浆花粉产品中总黄酮的含量为0．2393％（脱色前）或0．2447％（脱色后），水分含量24．48％，醚提物含量10．80％，醇提物含量41．77％；结论：用三氯化铝-醋酸钠比色法测定工浆花粉产品中总黄酮含量简便、准确。     

Ontogenetic movements of juvenile blacktip reef sharks: evidence of dispersal and connectivity between coastal habitats and coral reefs

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