Catchability of Atlantic salmon at high water temperatures: Implications for river closure temperature thresholds to catch and release angling     

Travis E. Van Leeuwen  Brian Dempson  David Cote  Nicholas I. Kelly  Amanda E. Bates 《Fisheries Management and Ecology》2021,28(2):147-157

Warming water temperatures, combined with increased mortality following catch and release, could have synergistic consequences if rivers remain open to catch and release at high water temperatures, and catchability of fish remains similar across water temperatures. Here archived data for Atlantic salmon, Salmo salar L., were used to (a) quantify the influence of water temperature on catchability and (b) refine estimates of absolute catch and release mortality to incorporate the relationship between temperature and catchability. A significant decline in the number of Atlantic salmon caught at warmer water temperatures was found after accounting for the effects of river water height, fishing effort, run duration and year-to-year differences in fish abundance. Overall, absolute catch and release mortalities were predicted to be infrequent at cool river temperatures. At river temperatures sometimes associated with fishing closures, mortality due to the catch and release ranged from 6% to 14%. Although post-release mortality increases with water temperature, it is somewhat compensated by the reduced catchability of Atlantic salmon. Thus, the catchability component of catch and release is an integral consideration when evaluating the effectiveness of river closure temperature thresholds when managing catch and release angling.  相似文献   

Parentally acquired differences in resource acquisition ability between brown trout from alternative life history parentage          下载免费PDF全文

Martin R. Hughes  Travis E. Van Leeuwen  Peter D. Cunningham  Colin E. Adams 《Ecology of Freshwater Fish》2018,27(1):62-69

Dominance hierarchies, where they exist, affect individual food acquisition ability and fitness, both of which have the potential to influence life history pathways. Juvenile salmonids exhibit clear dominance hierarchies in early life. As one of the drivers for the adoption of alternative life histories in salmonids is the relative rate of resource acquisition, there is potential for juvenile behaviour to influence the subsequent life history strategy of the individual. Lacustrine brown trout, Salmo trutta, exhibit a multitude of life histories which includes among others the piscivorous (ferox) life history where individuals grow to large size and have delayed maturity and benthivorous and pelagic life histories where individuals grow to much smaller sizes, however mature earlier. Using a number of observable characteristics of dominance, this study compared differences in behaviour between size‐matched pairs of progeny, reared under common garden conditions which are derived from alternative, co‐existing life history strategy parents. We found that first‐generation progeny of ferox trout were more aggressive, acquired more food, had lighter skin pigmentation and held more desirable positions than the progeny of benthivorous brown trout in an experimental stream system. Ferox trout progeny were dominant over benthivorous brown trout progeny in 90% of trials in dyadic contests. Given such clear differences in dominance, this study indicates that parentally acquired dominance‐related differences, passed through either, or both, of genetic and nongenetic (e.g. maternal effects) means, are likely a contributing factor to the continued maintenance of distinct life history strategies of brown trout.  相似文献   

Dietary 135-fold cholecalciferol supplementation severely disturbs the endochondral ossification in growing dogs     

Tryfonidou MA  Holl MS  Stevenhagen JJ  Buurman CJ  Deluca HF  Oosterlaken-Dijksterhuis MA  van den Brom WE  van Leeuwen JP  Hazewinkel HA 《Domestic animal endocrinology》2003,24(4):265-285

The effects of excessive non-toxic dietary Vitamin D₃ supplementation on Ca homeostasis with specific effects on endochondral ossification and skeletal remodeling were investigated in a group of growing Great Dane dogs supplemented with cholecalciferol (Vitamin D₃; HVitD) versus a control group (CVitD) (1350 μg versus 11.4 μg Vitamin D₃ per kilogram diet) from 6 to 21 weeks of age. There were no differences between groups in plasma concentrations of total Ca, inorganic phosphate, growth hormone, and insulin-like growth factor I and no signs of Vitamin D₃ intoxication in HVitD. For the duration of the study in HVitD compared to CVitD, plasma levels of parathyroid hormone (PTH) decreased, calcitonin (CT) increased, 25-hydroxycholecalciferol [25(OH)D₃] increased 30- to 75-fold, 24,25-dihydroxycholecalciferol [24,25(OH)₂D₃] increased 12- to 16-fold, and 1,25-dihydroxycholecalciferol [1,25(OH)₂D₃] decreased by approximately 40%. The latter was attributed to the two-fold increased metabolic clearance rate in the HVitD versus CVitD accompanied by the absence of the anabolic effect of PTH on the production of 1,25(OH)₂D₃. Fractional Ca absorption () did not differ between groups at 8 and 14 weeks of age, whereas at 20 weeks of age increased by only 16.4% in HVitD compared to CVitD. Excessive non-toxic Vitamin D₃ supplementation resulted in decreased bone remodeling and focal enlargement of the growth plate with morphology resembling those induced by administration of CT. Hypercalcitoninemia and the imbalanced relationship between 1,25(OH)₂D₃ and 24,25(OH)₂D₃ are potent candidates for the disturbed endochondral ossification.  相似文献   

Systemic toxicity of spinosad to the greenhouse whiteflyTrialeurodes vaporariorum and to the cotton leaf wormSpodoptera littoralis     

Thomas Van Leeuwen  Marc Van de Veire  Wannes Dermauw  Luc Tirry 《Phytoparasitica》2006,34(1):102-108

When spinosad was administered at the stem base of tomato plants grown in rockwool, the main substrate used in greenhouses in northern Europe, it was taken up by the roots and transported to the leaves. Laboratory toxicity experiments showed that systemically applied spinosad, at doses as low as 2 mg active ingredient per plant, gave excellent control of nymphs of the greenhouse whiteflyTrialeurodes vaporariorum, but was less toxic to adults. The toxicity of spinosad on Homoptera has not been documented yet and a dose-response relationship was established. The persistence of toxicity was at least 22 days for whitefly nymphs. A dose-response relationship of systemically applied spinosad was also determined on third-instar larvae of the cotton leaf wormSpodoptera littoralis; a dose of 5 mg per plant consistently killed all larvae. The persistence of systemically applied spinosad reached up to 45 days after treatment. Systemically applied spinosad was harmless to the parasitic waspEncarsia formosa. http://www.phytoparasitica.org posting Nov. 29, 2005.  相似文献   

The evaluation of the mobile nylon bag technique for determining the apparent protein digestibility in a wide variety of feedstuffs for pigs   总被引：2，自引：0，他引：2  

W C Sauer  L A den Hartog  J Huisman  P van Leeuwen  C F de Lange 《Journal of animal science》1989,67(2):432-440

Studies were conducted with four (50 to 70 kg) barrows to evaluate the mobile nylon bag technique (MNBT) for determining the apparent protein digestibility (AD) in a variety of feedstuffs. One-gram samples of each feedstuff, ground through a 1.0-mm mesh screen, were enclosed in nylon bags (25 X 40 mm; 48 microns mesh). Following predigestion (.01 N HCl; 4,000 Folin Intestinal Pepsin Units/liter), four bags of each sample were inserted into each pig via a duodenal T-cannula. The indigested contents were pooled within pig and feedstuff prior to crude protein analysis. The AD of each feedstuff was determined previously with four barrows according to the conventional method (CM), based on a 5-d total collection of feces following a 14-d adaptation period. The following results, AD (%), were obtained with the MNBT (n = 4) and CM (n = 4), respectively. Barley, 70.1 vs 81.2 (P less than .05); corn, 72.3 vs 82.1 (P less than .05); wheat, 79.6 vs 86.4 (P less than .05); corn gluten feed, 73.9 vs 70.9; rice bran, 57.3 vs 57.4; wheat middlings, 70.8 vs 79.4 (P less than .05); soybean meal, 89.9 vs 93.0; a mixture of soybean meal and hulls, 86.9 vs 88.8; coconut expeller, 65.0 vs 69.8; fababeans, 79.5 vs 78.5; peas, 87.6 vs 88.1; meat meal, 83.2 vs 84.0; complete diet (4.3% crude fiber), 76.3 vs 83.6 (P less than .05); and complete diet (13.6% crude fiber), 56.5 vs 55.0.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Factors affecting mummification and sporulation of pome fruit infected by Monilinia fructigena in Dutch orchards     

G. C. M. van Leeuwen  I. J. Holb  M. J. Jeger † 《Plant pathology》2002,51(6):787-793

A 2-year field experiment (1997–98, 1998–99) was conducted to study mummification and subsequent sporulation in spring of apple (cvs James Grieve, Golden Delicious) and pear (cv . Conference) fruits infected by Monilinia fructigena . Most mummified fruits were found in James Grieve and Conference, whereas in late-infected Golden Delicious, fruits were still soft when examined in April. In the first year, these late-infected fruits had a significantly higher sporulation intensity per sporulating fruit ( P  = 0·05) compared with Golden Delicious fruits infected 9 and 5 weeks before harvest maturity, which were partly mummified. It was concluded that early- and late-infected fruits contributed to primary inoculum in the next season. In a postinfection regime of 25°C and 65–75% relative humidity under controlled conditions, the number of Conference fruits sporulating decreased rapidly, and after 12 weeks' incubation sporulation had completely ceased. After 8 weeks' incubation, sporulation intensity in the postinfection regime at 10°C was significantly higher than that at 20 and 25°C in a first experiment with inoculated unripe fruit ( P  = 0·05). Results of a second experiment with ripe fruit were less clear. These results are discussed in relation to orchard disease management.  相似文献   

Mammary growth hormone and tumorigenesis--lessons from the dog   总被引：1，自引：0，他引：1  

Mol JA  Lantinga-van Leeuwen IS  van Garderen E  Selman PJ  Oosterlaken-Dijksterhuis MA  Schalken JA  Rijnberk A 《The Veterinary quarterly》1999,21(4):111-115

The discovery in the early 1990s that progestin-induced growth hormone (GH) excess in the dog originates in the mammary gland can be seen as a hallmark in the research on the pathogenesis of mammary cancer in the dog. The local biosynthesis and release of GH may provide a highly proliferative environment in the mammary gland, which contributes to the development and/or progression of mammary tumours. Before final goals such as prevention of tumour formation or inhibition of tumour promotion can be achieved it is of eminent importance to elucidate the mechanism of progesterone-induced mammary GH production and the mechanism of local autocrine/paracrine action of GH. These local GH effects may be achieved through direct growth stimulating effects of GH as well as by indirect effects mediated by the stimulation of the biosynthesis of insulin-like growth factor-I (IGF-I). The biological effects of the IGFs largely depend on the presence of IGF binding proteins (IGFBPs) which may both enhance or inhibit the activity of the IGFs. This review concentrates on recent advances in the understanding of the local mammary GH-IGF axis and the lessons which can be drawn from the dog for mammary cancer research in other species.  相似文献   

A real‐time (TaqMan) PCR assay to differentiate Monilinia fructicola from other brown rot fungi of fruit crops     

I. R. Van Brouwershaven  M. L. Bruil  G. C. M. Van Leeuwen  L. F. F. Kox 《Plant pathology》2010,59(3):548-555

To prevent the entry and spread of the brown rot fungus Monilinia fructicola in Europe, a fast and reliable method for detection of this organism is essential. In this study, an automated DNA extraction method combined with a multiplex real‐time PCR based on TaqMan chemistry was developed for fast, convenient and reliable detection of both the EU quarantine organism Monilinia fructicola and the three other brown rot fungi M. fructigena, M. laxa and Monilia polystroma. Using the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene repeat, a Monilinia genus‐specific primer pair and two differently labelled fluorogenic probes specific for M. fructicola and the group M. fructigena/M. laxa/Monilia polystroma were developed. The analytical specificity of the assay was assessed by testing 33 isolates of the four brown rot fungi and 13 isolates of related fungal species or other fungal species that can be present on stone and pome fruit. No cross‐reactions were observed. The assay was found to have a detection limit of 0·6 pg of DNA, corresponding to 27 haploid genomes or four conidia. Comparison of a manual DNA isolation followed by a conventional PCR with an automated DNA isolation combined with the presently developed real‐time PCR showed that the latter method gave improved results when tested with 72 naturally infected stone fruit samples. The detection rate increased from 65 to 97%.  相似文献   

Genetic Variation Among and Within Monilinia Species Causing Brown Rot of Stone and Pome Fruits     

C.E. Fulton  G.C.M. van Leeuwen  Averil E. Brown 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(5):495-500

Nucleotide sequence analysis of the internal transcribed spacer (ITS) regions 1 and 2 of the ribosomal DNA (rDNA) divided the three brown rot pathogens Monilinia laxa, M. fructicola and M. fructigena into four distinct groups. Isolates of M. fructigena received from Japan, which varied by 5 base substitutions in the ITS region from the European M. fructigena isolates, formed the fourth group. Four of five Japanese isolates of M. fructicola tested varied from the New World isolates in that they did not possess a group-I intron in the small subunit (SSU) rDNA. RAPD-PCR data indicated that isolates of M. laxa varied but were randomly distributed worldwide; ITS data indicated no apparent distinction between those from Malus spp. and those from Prunus spp. M. fructigena similarly did not cluster according to geographic origin. In contrast, M. fructicola isolates tended to be clustered according to their origin; Japanese isolates of M. fructicola clustered together and showed similarity to some of the New Zealand isolates. Isolates from USA and Australia were more variable.  相似文献   

Identification of pathotypes of Synchytrium endobioticum found in infested fields in Turkey     

E. Çak&#;r  G. C. M. van Leeuwen  K. Flath  J. P. Meffert  W. A. P. Janssen  S. Maden 《EPPO Bulletin》2009,39(2):175-178

Pathotypes of four isolates of Synchytrium endobioticum collected from the infested areas of Turkey were determined using Glynne–Lemmerzahl and Spieckermann test methods. Two isolates (Ordu 1 and Nevşehir 1) were tested by the Glynne–Lemmerzahl method in Germany. Ordu 1 was assigned as pathotype 1(D1) whereas the other isolate gave different results in 2 years of testing [pathotype 6(O1) or 18(T1)]. Two other isolates (Nevşehir 2 and Nevşehir 3) were tested using the Spieckermann method in Netherlands. Neither of these last two isolates tested were found to belong to the pathotypes known from Western Europe. The isolates Nevşehir 2 and Nevşehir 3 were given a new, unique code: 38 (Nevşehir).  相似文献