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Anadromous Fish (anadromous + fish)
Selected AbstractsA metapopulation perspective for salmon and other anadromous fishFISH AND FISHERIES, Issue 4 2007Nicolas Schtickzelle Abstract Salmonids are an important component of biodiversity, culture and economy in several regions, particularly the North Pacific Rim. Given this importance, they have been intensively studied for about a century, and the pioneering scientists recognized the critical link between population structure and conservation. Spatial structure is indeed of prime importance for salmon conservation and management. At first glance, the essence of the metapopulation concept, i.e. a population of populations, widely used on other organisms like butterflies, seems to be particularly relevant to salmon, and more generally to anadromous fish. Nevertheless, the concept is rarely used, and barely tested. Here, we present a metapopulation perspective for anadromous fish, assessing in terms of processes rather than of patterns the set of necessary conditions for metapopulation dynamics to exist. Salmon, and particularly sockeye salmon in Alaska, are used as an illustrative case study. A review of life history traits indicates that the three basic conditions are likely to be fulfilled by anadromous salmon: (i) the spawning habitat is discrete and populations are spatially separated by unsuitable habitat; (ii) some asynchrony is present in the dynamics of more or less distant populations and (iii) dispersal links populations because some salmon stray from their natal population. The implications of some peculiarities of salmon life history traits, unusual in classical metapopulations, are also discussed. Deeper understanding of the population structure of anadromous fish will be advanced by future studies on specific topics: (i) criteria must be defined for the delineation of suitable habitats that are based on features of the biotope and not on the presence of fish; (ii) the collection of long-term data and the development of improved methods to determine age structure are essential for correctly estimating levels of asynchrony between populations and (iii) several key aspects of dispersal are still poorly understood and need to be examined in detail: the spatial and temporal scales of dispersal movements, the origin and destination populations instead of simple straying rates, and the relative reproductive success of immigrants and residents. [source] Environmental signature in the otolith elemental fingerprint of the tapertail anchovy, Coilia mystus, from the Changjiang estuary, ChinaJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2006J. Yang Summary The ontogenetic patterns of habitat use and the migratory history of the tapertail anchovy, Coilia mystus, collected in the Changjiang estuary around Chongming Island, China, were studied by examining the environmental signature in the otolith strontium (Sr) and calcium (Ca) fingerprints using electron probe microanalysis (EPMA). Our results suggest that the migration strategy of C. mystus is much more flexible than supposed in the literature to date. The spring spawning population of C. mystus from the studied area was found to consist of individuals with different migration histories. Although the tapertail anchovy seems to be an anadromous fish that spawns and hatches in a freshwater habitat, it can also use a freshwater environment in non-spawning seasons. The otolith EPMA of the elemental fingerprint (Sr x-ray maps and Sr : Ca ratios) is an environmental indicator that can be applied to the migratory ecology of other important diadromous species in China. [source] Heritability of life-history tactics and genetic correlation with body size in a natural population of brook charr (Salvelinus fontinalis)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007V. THÉRIAULT Abstract A common dimorphism in life-history tactic in salmonids is the presence of an anadromous pathway involving a migration to sea followed by a freshwater reproduction, along with an entirely freshwater resident tactic. Although common, the genetic and environmental influence on the adoption of a particular life-history tactic has rarely been studied under natural conditions. Here, we used sibship-reconstruction based on microsatellite data and an ,animal model' approach to estimate the additive genetic basis of the life-history tactic adopted (anadromy vs. residency) in a natural population of brook charr, Salvelinus fontinalis. We also assess its genetic correlation with phenotypic correlated traits, body size and body shape. Significant heritability was observed for life-history tactic (varying from 0.52 to 0.56 depending on the pedigree scenario adopted) as well as for body size (from 0.44 to 0.50). There was also a significant genetic correlation between these two traits, whereby anadromous fish were genetically associated with bigger size at age 1 (rG = ,0.52 and ,0.61). Our findings thus indicate that life-history tactics in this population have the potential to evolve in response to selection acting on the tactic itself or indirectly via selection on body size. This study is one of the very few to have successfully used sibship-reconstruction to estimate quantitative genetic parameters under wild conditions. [source] Alternative migration and host parasitism strategies and their long-term stability in river lampreys from the River Endrick, ScotlandJOURNAL OF FISH BIOLOGY, Issue 10 2008C. E. Adams The stability of a discrete body size dimorphism of sexually mature river lamprey Lampetra fluviatilis from the River Endrick, Scotland, was examined over a 21 year period. Stable isotope analysis was used to test the hypothesis that the two size forms comprise individuals with differing migration and parasitic foraging strategies. Maturing river lamprey and the brook lamprey Lampetra planeri were trapped over 3 months each year in the periods 1983,1984 and 2004,2005. Brook lamprey catches and catches of both species combined showed no significant trend in catch rate with time. The catch rate of small body size river lamprey declined between 1983,1984 and 2004,2005 (although the difference did not reach statistical significance; P = 0·055). In contrast, there was a significant increase in the catch rate of the large body size river lamprey and as a consequence, a significant change in the relative proportion of each of the two river lamprey morphs over the study period. Analysis of the stable isotopes of C and N in muscle tissue showed that brook lamprey tissue derived its carbon from a freshwater source and had a ,13C more consistent with that of the River Endrick than with Loch Lomond. ,15N values for this species showed it to be feeding at the base of the food chain, consistent with filter feeding as an ammocoete. The large body size and the small body size river lamprey adults differed substantially in their ,13C values, with the small body size ,13C signature indicative of a freshwater carbon source and the large body size morph of a marine source. The small body size morph had a ,13C signature that was consistent with that of Loch Lomond powan Coregonus lavaretus suggesting that they share a common carbon source. The large body size morph was clearly feeding at a higher trophic level than the small body size morph. A single small body size river lamprey individual with typical morphology for that group, however, had C and N signatures that clustered with those of the large body size morphs. This individual had either migrated to sea to forage, as is typical for the species, or had been feeding on an anadromous fish with a strong marine C signature in fresh water. It is concluded that the body size dimorphism is indicative of a differential migration and foraging strategy in the parasitic phase of the life cycle of river lamprey at this site. [source] Fine structure and development of the retina of the grenadier anchovy Coilia nasus (Engraulididae, Clupeiformes)JOURNAL OF MORPHOLOGY, Issue 1 2001Christoph Haacke Abstract A study of the morphogenesis of the grenadier anchovy retina was undertaken using light and electron microscopy. Five developmental stages from prelarvae 3 days after fertilization to adult fish were studied. In addition to the general morphology of the eye and retina, special emphasis was given to the development of the photoreceptors and pigment epithelium (PE). The earliest retinae showing structural features indicative of a functioning eye are pure cone retinae composed of rows of alternating long and short cones forming a transient, tesselated pattern. At this stage there is a conventional PE containing melanin. In older stages cone rows are separated by the newly formed rods and by PE wedges filled with diffusely reflecting guanine crystallites. The findings are compared with the retinae of other engraulidids and with the development of teleost retinae in general. Moreover, the observed structural changes are discussed with respect to the photic habitat conditions of these anadromous fish that move between coastal waters, estuary, and river. J. Morphol. 248:41,55, 2001. © 2001 Wiley-Liss, Inc. [source] LANDSLIDE INITIATION, RUNOUT, AND DEPOSITION WITHIN CLEARCUTS AND OLD-GROWTH FORESTS OF ALASKA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2000A. C. Johnson ABSTRACT: More than 300 landslides and debris flows were triggered by an October 1993 storm on Prince of Wales Island, southeast Alaska. Initiation, runout, and deposition patterns of landslides that occurred within clearcuts, second-growth, and old-growth forests were examined. Blowdown and snags, associated with cedar decline and "normal" rates of mortality, were found adjacent to at least 75 percent of all failures regardless of land use. Nearly 50 percent of the landslides within clearcuts occurred within one year following timber harvest; more than 70 percent of these sites had hydrophytic vegetation directly above failures. In following the runout paths of failures, significantly more erosion per unit area occurred within clearcuts than in old-growth forests on slopes with gradients from 9 to 28* (16 to 54 percent). Runout length, controlled by hillslope position within deglaciated valleys, was typically longer in old-growth forests than in second growth and clearcuts (median values were 334, 201, and 153 m, respectively). Most landslides and debris flows deposited in first-and second-order channels before reaching the main stem channels used by anadromous fish. Slide deposits in old-growth forests were composed of a higher proportion of woody debris than deposits derived from slides in second growth or clearcuts. [source] Microsatellites assessment of Chinese sturgeon (Acipenser sinensis Gray) genetic variabilityJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2005N. Zhao Summary Four microsatellites were used to examine the genetic variability of the spawning stocks of Chinese sturgeon, Acipenser sinensis, from the Yangtze River sampled over a 3-year period (1999,2001). Within 60 individuals, a total of 28 alleles were detected over four polymorphic microsatellite loci. The number of alleles per locus ranged from 4 to 15, with an average allele number of 7. The number of genotypes per locus ranged from 6 to 41. The genetic diversity of four microsatellite loci varied from 0.34 to 0.67, with an average value of 0.54. For the four microsatellite loci, the deviation from the Hardy,Weinberg equilibrium was mainly due to null alleles. The mean number of alleles per locus and the mean heterozygosity were lower than the average values known for anadromous fishes. Fish were clustered according to their microsatellite characteristics using an unsupervised ,Artificial Neural Networks' method entitled ,Self-organizing Map'. The results revealed no significant genetic differentiation considering genetic distance among samples collected during different years. Lack of heterogeneity among different annual groups of spawning stocks was explained by the complex age structure (from 8 to 27 years for males and 12 to 35 years for females) of Chinese sturgeon, leading to formulate an hypothesis about the maintenance of genetic diversity and stability in long-lived animals. [source] Conservation and management implications of fine-scale genetic structure of Gulf sturgeon in the Pascagoula River, MississippiJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2004M. A. Dugo Summary The anadromous Gulf sturgeon occurs along the north central coast of the Gulf of Mexico and is federally listed as threatened. We analyzed fine-scale patterns of Gulf sturgeon population structure, focusing on the Pascagoula River drainage of Mississippi, in reference to movement patterns as determined via telemetry and capture data. We genotyped 361 Gulf sturgeon using eight microsatellite loci including samples from the Pascagoula, Pearl, Escambia, Yellow, Choctawhatchee, and Apalachicola river drainages. Pairwise FST estimates indicated that genetic structure occurs at least at the drainage level. The Pascagoula and Pearl rivers form a western group, demonstrating 100% bootstrap support for a division with drainages to the east. Assignment tests detected non-natal genotypes occurring in all drainages. According to assignment tests, the Pascagoula supports an admixture of individuals, containing minimal influence from drainages to the east (2%) and substantial interaction with the Pearl River (14.1%). The occurrence of Pascagoula River fish in the Pearl was non-reciprocal, observed at 1.1%. After accounting for non-natal genetic diversity within the Pascagoula, there remained a disparity between a pooled Pascagoula group and the only documented spawning site within the drainage located in the Bouie River. We interpret this as an indication of a second genetic stock within the Pascagoula River drainage. Radio telemetry data suggest that spawning likely occurs in the Chickasawhay River, in areas isolated from the Bouie River spawning site by about 350 river kilometers. We emphasize the utility of integrating field and molecular approaches when delineating fine-scale patterns of population structure in anadromous fishes. [source] | |||||||||||||