bluuebunny/crossref_metadata_2025 huggingface dataset:
Foraging ecology and patterns of diversification in dipteran parasitoids of fire ants in south Brazil
Authors: ORR MATTHEW , SEIKE SERGIO , GILBERT LAWRENCE
Published: November 2003

1. At least sixteen species of parasitoid flies in the genus Pseudacteon (family Phoridae) attack fire ants in the Solenopsis saevissima subcomplex in South America. Little is known of behavioural or ecological differences among Pseudacteon parasitoids of fire ants, although their coexistence in multispecies communities would suggest that important differences exist. Seven Pseudacteon species in two separate communities were studied in south‐east Brazil. The way in which hosts detect and respond to the presence of parasitoids, attack rates of the parasitoids, and host location behaviour of the parasitoids were examined.

2. Reductions in fire ant recruitment were more closely related to the number of ants attacked along a foraging trail than to the amount of time that a phorid was present.

3. Pseudacteon solenopsidis differed from other phorid species by flying backwards while pursuing ants, by attacking at lower rates than other phorids, and by spending longer around fire ant foraging trails than other phorids before departing. Fire ant recruitment to food often rebounded in the continued presence of P. solenopsidis.

4. In each of the two communities, certain Pseudacteon species appeared frequently at Solenopsis foraging trails, whereas others appeared predominantly at mound disturbances. Two distinct size classes of phorids were present in each community, and the community with the larger ant host species also had a third and larger phorid species. No phorid species from the same community had similar body sizes and similar host location behaviours, although numerous species from different communities shared both of these traits.

5. Heterogeneity in host size and in the ecological circumstances under which hosts are vulnerable to attack appears to have influenced the evolution and perhaps maintenance of diverse Pseudacteon communities.
Three ways of assessing metapopulation structure in the butterfly Plebejus argus
Authors: LEWIS OWEN , THOMAS CHRIS , HILL JANE , BROOKES MARTIN , CRANE T. P. , GRANEAU YVONNE , MALLET JAMES , ROSE OWEN
Published: November 2003

1. Three independent methods were used to investigate population structure in the butterfly Plebejus argus. First, migration and dispersal ability were measured by mark–release–recapture in seven adjacent habitat patches, and by release of butterflies in unoccupied habitat. Secondly, colonization of newly created habitat was observed over 7 years. Finally, genetic differentiation of local populations within a metapopulation was investigated. Sampled local populations included parts of the mark–release–recapture study area.

2. Plebejus argus is relatively sedentary: the maximum movement detected was 395 m, and only 2% of individuals moved further than 100 m between recaptures on different days. None the less, adjacent local populations in the mark–release–recapture study area were linked by occasional migration, with ≈ 1.4% of individuals moving between patches separated by 13–200 m.

3. Despite low mobility, observed colonizations occurred rapidly over distances of 1 km. Because P. argus occurs at high population densities, 1.4% migration can generate enough migrants to colonize newly suitable habitat quickly at this spatial scale.

4. Mark–release–recapture data were used to predict that there would be limited genetic differentiation through drift between local populations at this spatial scale. The prediction was supported by allele frequency data for the same local populations.

5. Genetic differentiation often indicates higher levels of migration than are revealed by the movements of marked individuals. This study shows that when experimental releases and extensive marking are undertaken in areas that are large relative to most movements, indirect measures of gene flow and direct measures of dispersal can concur.

6. Evidence from the three different approaches was complementary, indicating that P. argus occurs as metapopulations within the study area.
Controlling resource acquisition to reveal a life history trade‐off: egg mass and clutch size in an iteroparous seed predator, Prostephanus truncatus
Authors: GUNTRIP J. , SIBLY R. M. , SMITH R. H.
Published: November 2003

1. A trade‐off constraining egg production was investigated and the consequences of egg mass for the offspring life history in Prostephanus truncatus investigated. Fresh egg mass was found to vary between 0.065 and 0.109 mg (about 20% of fresh body mass at emergence) and was correlated both with dry egg mass (r = 0.8) and with the mass of first‐instar larvae (r = 0.8).

2. There was a negative correlation between egg mass and clutch size: doubling clutch size from eight to sixteen eggs resulted in a reduction in egg mass from 0.09 to 0.07 mg. Resource allocation per clutch was not constant but increased with clutch size. After allowing for the relationship between egg mass and clutch size, heavier females were found to oviposit both heavier eggs and more eggs in a clutch.

3. By placing eggs in prepared seeds that minimized variation in resource acquisition, it was discovered that development period of females, but not of males, was negatively correlated with egg mass. Egg size was not correlated with body size at emergence in either sex.

4. The results are interpreted as revealing a resource‐allocation trade‐off in egg production.
Factors affecting size, longevity and fecundity in the reindeer oestrid flies Hypoderma tarandi (L.) and Cephenemyia trompe (Modeer)
Authors: NILSSEN ARNE
Published: November 2003

1. Laboratory reared reindeer oestrid flies Hypoderma tarandi and Cephenemyia trompe (Diptera: Oestridae) were weighed to determine progressive weight loss and death weights at treatments with various temperature and humidity conditions.

2. Four individual measurements of size were taken: larval weight, wet weight of newly eclosed flies, wing length, and weight of flies after dehydration and fat extraction. In H. tarandi, males were bigger than females (except for wing length), whereas the reverse was true for C. trompe.

3. Size variation was not significantly related to conditions (temperature, humidity, duration) during the pupal stage, but individual reindeer produced flies (both species) of different mean sizes. These size differences were not correlated with larval burden (= number of larvae per individual host), but are hypothesized to be connected to unknown host quality factors.

4. Longevity of flies kept in vials and subjected to various temperature and humidity conditions revealed that C. trompe lived significantly longer than H. tarandi (range: 4–44 and 1.2–27 days, respectively) at 5–33 °C. Male H. tarandi survived longer than females; female C. trompe survived longer than males. Longevity was not significantly correlated to any of the size measures.

5. Most flies had a large portion of their fat reserves left at death.

6. In H. tarandi, mean number of eggs was 609 ± SD 73 (range 354–772, n = 119). Egg number was slightly dependent on larval size, but not on wet weight of newly eclosed flies or wing length. In C. trompe, mean number of eggs was 960 ± SD 208 (range 493–1349, n = 31).

7. The possible adaptive value of large size in oestrids is questioned. Benefits of flexibility in size in oestrids are hypothesized.
The relative efficiencies of Latin square and randomized complete block designs for insect trapping experiments: an investigation using field data on tsetse flies
Authors: ODULAJA A. , ABU‐ZINID I. M.
Published: November 2003

1. The Latin square design (LSD) is usually preferred over the randomized complete block design (RCBD) in insect trapping experiments because of its ability to cater for variations due to both sites and days in addition to treatments.

2. The efficiency of LSD relative to RCBD is quantified for tsetse trapping experiments using a data set comprising 2200 trap‐days. LSD was found to be more efficient than RCBD when blocks ≅ days, but less efficient when blocks ≅ sites, especially when experiments involve only three or four treatments.

3. The importance of sites relative to days as sources of variation in tsetse trapping experiments is quantified. Effects due to site differences were shown to be more important than day to day variability.

4. By relating LSD relative efficiency to the relative importance of sites, it was found that LSD efficiency depended on the relative magnitude of effects of sites and days.
Preferences for nectar sugars in the peacock butterfly, Inachis io
Authors: RUSTERHOLZ HANS‐PETER , ERHARDT ANDREAS
Published: November 2003

1. Peacock butterflies, Inachis io, were tested experimentally for their preferences for nectar sugars.

2. In tests with different plain sugar solutions (25%, weight to total weight) the butterflies strongly preferred sucrose and fructose over glucose. They also preferred sucrose over fructose.

3. In tests with mixed sugar solutions the butterflies clearly preferred both sucrose‐dominant (sucrose : hexoses = 5 : 1) and balanced sugar solutions (sucrose : glucose : fructose = 1 : 1 : 1) over hexose‐dominant sugar solutions (sucrose : hexoses = 1 : 5).

4. Females consumed significantly more of the balanced sugar solution than did males.

5. These results are discussed with respect to previous experiments on nectar preferences of butterflies, nectar sugar composition of butterfly‐pollinated flowers, and flower preferences, physiological and reproductive aspects of butterflies.
Relationship of queen number and queen relatedness in multiple‐queen colonies of the fire ant Solenopsis invicta
Authors: GOODISMAN MICHAEL , ROSS KENNETH
Published: November 2003

1. The relationship between the number of queens per nest and their relatedness was examined in the polygyne (multiple queens per nest) social form of the fire ant Solenopsis invicta.

2. No significant relationship between these two variables was found. Moreover, the overall average relatedness among nestmate queens was not significantly different from zero.

3. These findings indicate that polygyne nests of S. invicta do not represent closed societies. Furthermore, they are consistent with continual acceptance of non‐nestmate queens throughout a colony’s lifetime. This strategy differs from the expectation of kin selection theory that only related queens should be accepted as new reproductives within polygyne colonies.

4. The postulated acceptance of non‐nestmate queens is associated with a decrease in the number of parasites, predators and diseases and a concomitant increase in the density of nests in introduced populations, suggesting that the permissive environment experienced by introduced fire ants may have decreased the relative importance of kinship as a stabilizing factor in the evolution of polygyny.
The pay‐off from superparasitism in the egg parasitoid Trissolcus basalis, in relation to patch defence
Authors: FIELD SCOTT , KELLER MICHAEL , CALBERT GREG
Published: November 2003

1. In species such as quasi‐gregarious egg parasitoids, which exploit defendable patches, the fitness pay‐off from superparasitism is an important factor in considering the evolution of patch defence and optimal patch defence strategies.

2. When oviposition in a previously parasitized host has a non‐zero fitness pay‐off, competing parasitoids are not only able to diminish the future value of a patch to other females by depleting unparasitized hosts, but also devalue the previous investment of other females in the patch by superparasitizing.

3. In Trissolcus basalis, an egg parasitoid of pentatomid bugs, the fitness pay‐off from superparasitism is higher than 0.5 when the time interval between ovipositions is less than 3 h, suggesting that defending a previous investment will be an important component of patch defence behaviour.

4. The data suggest a mechanism for the high early pay‐off, which involves the superparasitizing female adjusting the sex ratio of its offspring in favour of males. Males develop more quickly than females and thus may have a competitive advantage.
HLA‐DR AND ‐DQB1 DNA POLYMORPHISMS IN A VIETNAMESE KINH POPULATION FROM HANOI
Authors: VU‐TRIEU A. , DJOULAH S. , TRAN‐THI C. , NGYUYEN‐THANH T. , LE MONNIER DE GOUVILLE I. , HORS J. , SANCHEZ‐MAZAS A.
Published: November 2003

We report here the DNA polymerase chain reaction sequence‐specific oligonucleotide (PCR‐SSO) typing of the HLA‐DR B1, B3, B4, B5 and DQB1 loci for a sample of 103 Vietnamese Kinh from Hanoi, and compare their allele and haplotype frequencies to other East Asiatic and Oceanian populations studied during the 11th and 12th International HLA Workshops. The Kinh exhibit some very high‐frequency alleles both at DRB1 (1202, which has been confirmed by DNA sequencing, and 0901) and DQB1 (0301, 03032, 0501) loci, which make them one of the most homogeneous population tested so far for HLA class II in East Asia. Three haplotypes account for almost 50% of the total haplotype frequencies in the Vietnamese. The most frequent haplotype is HLA‐DRB1*1202‐DRB3*0301‐DQB1*0301 (28%), which is also predominant in Southern Chinese, Micronesians and Javanese. On the other hand, DRB1*1201 (frequent in the Pacific) is virtually absent in the Vietnamese. The second most frequent haplotype is DRB1*0901‐DRB4*01011‐DQB1*03032 (14%), which is also commonly observed in Chinese populations from different origins, but with a different accessory chain (DRB4*0301) in most ethnic groups. Genetic distances computed for a set of Asiatic and Oceanian populations tested for DRB1 and DQB1 and their significance indicate that the Vietnamese are close to the Thai, and to the Chinese from different locations. These results, which are in agreement with archaeological and linguistic evidence, contribute to a better understanding of the origin of the Vietnamese population, which has until now not been clear.
IMMUNOGENETICS OF HENOCH–SCHOENLEIN DISEASE
Authors: AMOROSO A. , BERRINO M. , CANALE L. , COPPO R. , CORNAGLIA M. , GUARRERA S. , MAZZOLA G. , SCOLARI F.
Published: November 2003

In order to investigate the genetic basis of susceptibility to Henoch–Schoenlein purpura (HS), blood samples of 152 patients, 105 of whom had renal disease, were collected in a two‐step study. The evaluation of DRB, DQB and DQA polymorphism was done by analysis of the restriction polymorphisms produced by TaqI enzyme. DRB1*07 was less frequent in patients than in the control group (gene frequency 0.09 and 0.18, respectively; P = 0.0023), whereas 64% of the patients were positive for DRB1*01 and/or DRB1*11 compared with 48% of the control group (P = 0.0069). Polymerase chain reaction–sequence‐specific oligonucleotide (PCR‐SSO) typing of DRB1*01‐ and DRB1*11‐positive individuals did not show any deviation of frequencies of DRB1*01 subtypes between patients and controls, whereas among DRB1*11 subtypes DRB1*1104 was significantly increased in the patients (Pc = 0.033). The comparison between patients with renal disease and those without renal disease showed no significant differences in the frequency of the single DRB, DQB and DQA alleles. The study of restriction polymorphisms in the switch region of the constant genes α1, α2 and μ of the heavy chains of immunoglobulins, using the enzyme Sacl and a specific probe, did not show any difference between 44 patients and 54 controls. This study demonstrates that susceptibility to HS also has a genetic origin: on one hand, the presence of DRB1*01 or DRB1*11 makes disease onset easier; on the other hand, DRB1*07 could induce some resistance to the disease. It is suggested that, as well as for other diseases caused by an impaired immune response, single amino acids in a key position in the HLA‐DRB molecule make it more or less easy to recognize some antigenic peptide, towards which an immune response leading to disease is triggered.
NO ASSOCIATION OR LINKAGE TO IDDM OF AN INTERFERON REGULATORY FACTOR‐1 GENE POLYMORPHISM IN A DANISH POPULATION
Authors: JOHANNESEN J. , KARLSEN A. E. , NERUP J. , POCIOT F. , CHILDHOOD THE DANISH STUDY GROUP FOR DIABETES IN
Published: November 2003

Nitric oxide is a potent mediator of the cytokine‐induced cytotoxic effect on pancreatic β cells. It has been shown that the inducible nitric oxide synthase (iNOS) is induced in islets of Langerhans by interleukin‐1β (IL‐1β). Interferon regulatory factor‐1 (IRF‐1), a transcriptional factor known to play an essential role in the induction of the inducible nitric oxide synthase, has also been shown to be induced by IL‐1β in isolated islets of Langerhans. In the present study we analysed a GT nucleotide repeat polymorphism in the intron 7 of the IRF‐1 gene. We typed 123 Danish Caucasian insulin‐dependent diabetes mellitus (IDDM) multiplex families (550 individuals including 271 diabetic patients) and 108 control subjects of Danish Caucasian origin. In total, seven alleles were identified. No significant differences in either allele or genotype distribution were found comparing IDDM patients with control subjects (P = 0.7 and P = 0.5, respectively). An extended transmission disequilibrium test (ETDT) did not reveal transmission disequilibrium in an allele‐wise manner. A 16‐nucleotide deletion was found when sequencing the region containing the polymorphic GT repeat. This new deletion was in linkage disequilibrium with the GT‐repeat polymorphism, as it was only seen with alleles of more than 13 GT tandem repeats. No association with IDDM for the deletion was observed. Furthermore, three single base substitutions linked to the 16 nucleotide deletion were identified. Even though we could not associate the GT‐repeat polymorphism to IDDM in this study, additional mutation screening is warranted, as we still think the IRF‐1 gene is a potential candidate gene for IDDM.
HLA‐DQA, ‐DQB AND ‐DRB ALLELE CONTRIBUTION TO NARCOLEPSY SUSCEPTIBILITY
Authors: PLANELLES D. , PUIG N. , BENETO A. , GOMEZ E. , RUBIO P. , MIRABET V. , BONANAD S. , BLASCO I. , MONTORO J. A.
Published: November 2003

The association of narcolepsy with HLA class I antigens and HLA class II alleles was studied in a series of Spanish narcoleptic patients. The haplotype DRB1*1501‐DRB5*0101‐DQA1*0102‐DQB1*0602 was found to be significantly associated with the disease, while the haplotype DRB1*0701‐DRB4*01‐DQA1*0201‐DQB1*02 might confer a slight protective effect against narcolepsy. Gene dose–effect was not seen in any of the involved alleles, and linkage disequilibrium between the positively associated alleles was found to be stronger in patients than in controls. Statistical analysis applied to identify the HLA allele truly responsible for the association did not clearly discriminate between the contribution of DRB1*1501 and that of DQB1*0602, but it proved that the association with DQA1*0102 is secondary to that with DRB1*1501/DQB1*0602. Analysis of the diagnostic value of typing for the narcolepsy‐associated alleles demonstrated a very high negative predictive value and revealed that this test can be convenient for exclusion of narcolepsy in cases when the diagnosis is not evident after clinical evaluation and the marker haplotype is absent. Finally, a family study indicated that narcolepsy is a multifactorial disorder that involves HLA genes under an incomplete penetrance model, with possible influences from environmental factors or other genes different to HLA genes.
HIERARCHY OF SPEA PRESENTATION TO T CELLS BY MOUSE MHC HAPLOTYPES
Authors: CHARLTON F. G. , SMITH R. J. , PYLE G. , KEHOE M. A. , ROBINSON J. H.
Published: November 2003

The ability of splenic antigen‐presenting cells (APC) from nine independent mouse major histocompatibility complex (MHC) haplotypes to present recombinant streptococcal exotoxin A (rSPEA) to heterogeneous T cells and mouse T cell clones were compared using proliferation assays. We report that there is marked variation between MHC haplotypes, which can be ranked as follows: H2z > H2s = H2f = H2p = H2r = H2k > H2d > H2b = H2q. In some haplotypes both A and E molecules bind rSPEA with low affinity. In addition, we show that presentation is preferentially by E molecules in haplotypes where A and E are co‐expressed, but that A alleles also bind and present rSPEA, based on inhibition of responses by anti‐E and anti‐A mAbs. Furthermore, using strains of mice which fail to express E, we demonstrate that As and Af present rSPEA with high efficiency, whereas Aq and Ab are the least efficient of all haplotypes. The results suggest that there is significant variation in the ability of different alleles of both E and A molecules to bind and present rSPEA.
COMPILATION OF DISTINCT HLA‐A, ‐B AND ‐C TRANSMEMBRANE AND CYTOPLASMIC DOMAIN‐ENCODING SEQUENCES
Authors: CREW M. D.
Published: November 2003

Exons 5–8 of HLA class I genes encode the transmembrane and cytoplasmic domains of HLA class I proteins. Of the more than 300 HLA‐A, ‐B and ‐C alleles recognized by the WHO Nomenclature Committee for Factors of the HLA System, the number of alleles for which exon 5–8 sequence information is available and the extent of genetic variability in this region are undocumented. Thus, a comprehensive analysis of HLA‐A, ‐B and ‐C exon 5–8 sequence variability was undertaken. Of 219 HLA‐A, ‐B and ‐C alleles for which exon 5–8 sequences are known, 40 unique HLA‐A, ‐B and ‐C exon 5–8 sequences were identified. At the amino acid level, these encode 28 distinct HLA‐A, ‐B and ‐C transmembrane and cytoplasmic domains.
SEQUENCE OF HLA‐DRB1*0818 IN A BONE MARROW DONOR
Authors: KERVAIRE B. , TIERCY J.‐M.
Published: November 2003

Exon 2 of a new HLA‐DR8 subtype, DRB1*0818, was cloned and sequenced in a volunteer bone marrow donor. This new allele differs from DRB1*0805 by one single nucleotide in codon 67 resulting in an amino acid substitution from phenylalanine to isoleucine. Codon 67 dimorphism apppears to be more frequent in DR8 and DR11 haplotypes. The HLA typing of the donor was A*0201/33 B*51/4403 Cw*0202/14 DRB1*0408/0818 DQB1*0302/0402. This new HLA‐DR8 variant is very rare, at least in Caucasoids.
Dissolved organic matter and its parent organic matter in grass upland soil horizons studied by analytical pyrolysis techniques
Authors: Huang Y. , Eglinton G. , Van Der Hage E. R. E. , Boon J. J. , Bol R. , Ineson P.
Published: November 2003

We have sought to understand the molecular mechanisms by which dissolved organic matter (DOM) forms and soil organic matter (SOM) degrades in upland peaty gley soil under grass. Pyrolysis mass spectrometry (Py‐MS) and pyrolysis gas chromatography mass spectrometry (Py‐GC/MS) were applied to characterize the DOM collected from lysimeters and its parent SOM. The macromolecular organic matter in the litter and fermentation (Lf) horizon of the soil consists primarily of little decomposed lignocellulose from grass, whereas the humus (Oh) horizon is characterized by an accumulation of selectively decomposed lignocellulose material, microbial metabolites and bound fatty acids. The mineral horizon produced a relative enrichment of furan structures derived from microbial reworking of plant polysaccharides but virtually no lignin signals. A series of exceptional long chain C43to C53fatty acids with odd over even predominance, probably derived from mycobacteria, were also identified in the Oh horizon. Side‐chain oxidation and shortening, increase of carboxyl functionality and selective removal of syringyl (S) > guaiacyl (G) > p‐hydroxyphenyl (P) lignin units were the main reactions when lignin degraded. Compared with SOM, the DOM shows a large accumulation of more oxidized lignin and aromatic structures, especially those containing carboxylic and dicarboxylic acid functionalities and with shorter side‐chain length. The polysaccharide‐type compounds in the DOM were more modified (greater abundance of furan structures in pyrolysis products), and had significantly lower molecular weight and more diverse polymeric structures than did those in soils. Increased temperature and rainfall appeared to result in greater relative abundance of lignin degradation products and aromatic compounds in DOM.
A comparison of late eighteenth century and present‐day fishery surveys on the River Witham, Lincolnshire, UK
Authors: FORBES I. , WHEELER A.
Published: November 2003

A late‐eighteenth century manuscript recording the netted catches of fish in the lower River Witham, Lincolnshire, UK by Joseph Banks was analysed to provide the total weights and numbers of pike, Esox lucius L., perch, Perca fluviatilis L., eels, Anguilla anguilla (L.) and unsorted cyprinids. A number of records of less common fish, including burbot, Lota lota (L.), were reported. These results were compared with the results from present‐day surveys and the average weight of pike, perch and eels appears to have been greater in the eighteenth century.
Effects of rearing technique and fish size on post‐stocking feeding, growth and survival of European grayling, Thymallus thymallus (L.)
Authors: CARLSTEIN M.
Published: November 2003

European grayling, Thymallus thymallus (L.), were reared by four different techniques: (A) in a natural pond without a supply of artificial diet; (B) in a net pen fed artificial dry diet; (C) in tanks fed artificial dry diet; (D) in tanks, and for 16 days before stocking, transferred to a diet based on mixed frozen natural food exclusively. Fish within groups C and D were also split into subgroups of large and small fish. Feeding, growth and survival of fish in the different groups were compared after stocking into three different stocking sites during the spring of 1994. The stocking sites consisted of a barren lake (Lake L), a second lake (Lake N) containing an allopatric perch, Perca fluviatilis L., population, and a barren man‐made pond. In Lake L, higher recapture rates and mean weights of stomach contents were obtained in fish reared in the natural pond and in the net pen. There were no differences in total recapture rate, or mean condition factor between small and large fish within groups C and D. In Lake N only five (0.5%) stocked grayling from rearing groups A and B were recaptured during the experiment and more fish from categories C and D were recaptured. This was probably related to size‐selective predation. In the pond, there were no differences in recapture rates or in mean weight of stomach contents between fish from any of the groups. In sample 1 (Lake N, 22 days after stocking), mean weight of stomach contents was higher in the larger fish within categories C and D but there was no difference in condition factor between the groups. In sample 1, mean condition factor of fish from the different groups varied markedly, being highest in Lake L followed by Lake N and the Pond. Fourteen out of 26 dead fish in the pond showed clinical symptoms of the bacterial disease ASA. Mortality was related to low initial condition factor at the time of stocking. No stocked grayling were recaptured from the two lakes in the last sample (June 1995).
Movements of Atlantic salmon, Salmo salar L., parr and brook trout, Salvelinus fontinalis (Mitchill), in lakes, and their impact on single‐census population estimation
Authors: ERKINARO J. , GIBSON R.J.
Published: November 2003

Three small Newfoundland lakes were fished to estimate the population sizes of Atlantic salmon, Salmo salar L., parr and brook trout, Salvelinus fontinalis (Mitchill), and to study within‐lake movements of the species. The whole shoreline of the lakes was seined, the catches in different sections were recorded separately and the fish were given different marks. Estimates for the lakes derived from different subareas were constantly lower than the estimate derived by using the data from the whole shoreline. If estimates of the different sub‐areas were extrapolated according to their proportion of the shoreline, they were positively biased, and showed higher variance. Significant correlations between the movement rates and the accuracy of sub‐area population estimates and recapture rates were found. Validation of the assumption of random mixing of marked and unmarked fish, when a spatially stratified sampling is carried out, is emphasized.
Presentation and first applications of a dynamic population model for brown trout, Salmo trutta L.: aid to river management
Authors: SABATON C. , SIEGLER L. , GOURAUD V. , BAGLINIÈRE J.L. , MANNÉ S.
Published: November 2003

A mathematical model representing the long‐term change in a trout population under different river management scenarios is presented. It describes the structure of a population broken down into age classes based on the Leslie matrix; if the population structure for any given month is known, the model should be able to estimate that of the following month. The passage from one month to the next takes into account various relevant factors: survival rate of individuals in the different age classes; fertility rate of females; linear and weighted growth rates; displacement linked to habitat fluctuations using weighted usable area (WUA) values. The model was applied to two French rivers. Regular monitoring of trout populations on the River Kernec enabled comparison of the response of the model with no displacement, with actual variations in fish stocks on the first river. In addition, the knowledge of WUA chronologies on the River Echez made it possible to carry out initial simulations of the response of a fish population to different river management scenarios at the second site.
Formulation of management strategies for two exploited West African prawn populations
Authors: ENIN U. I.
Published: November 2003

The life histories of the estuarine prawn, Nematopalaemon hastatus Aurivillius, and the brackish river prawn, Macrobrachium macrobrachion Herklots, were compared in relation to their seasonal exploitation patterns in the Cross River estuary, Nigeria. The period of intensive exploitation of N. hastatus (March to June) was outside the main spawning season (July to October), because these prawns migrate from the main fishing area in the estuary and near shore coastal waters into the deeper continental shelf waters to spawn. This probably contributes to their reproductive success and conservation of the stock. With M. macrobrachion, the peak spawning period and the major fishing season converge between July and September. These prawns also migrate from the fresh water into the major fishing zone within the estuary during the spawning season. This exposes the spawning population to intense human exploitation. On the basis of their spawning dynamics, M. macrobrachion requires more urgent management attention. An option would be a closed season for M. macrobrachion within the estuary during the spawning period.
Reduction of brown trout, Salmo trutta L., salmon, S. salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), smolt bycatches in eel pound nets
Authors: DIEPERINK C. , RASMUSSEN P.C.
Published: November 2003

Two types of bycatch reduction devices (BRDs) were tested in the Randers Fjord, Denmark, aimed at deflecting the surface‐oriented smolts of brown trout, Salmo trutta L., salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), before they became trapped, while retaining the catches of eel, Anguilla anguilla (L.). The methods tested were: a) placing a floating guard net between the wings; and b) submerging the pot net (i.e. last enclosure before fyke net) 55–100 cm below mean sea level. After each haul the pound net‐setups were changed from the control to one of the types of BRD, and vice versa. Both methods significantly reduced the bycatch of brown trout smolts, while catches of legal‐sized eels were not affected. Submerging the pot net reduced smolt catches of all species; mean reductions were 91.1% for brown trout, 74.5% for rainbow trout, and 86.1% for salmon.
Patterns of genetic divergence in Chondrostoma lusitanicum Collares‐Pereira, in intermittent Portuguese rivers
Authors: COELHO M.M. , ALVES M.J. , RODRIGUES E.
Published: November 2003

Samples collected from throughout the range of Chondrostoma lusitanicum Collares‐Pereira, were examined electrophoretically for patterns of variation at 24 presumptive gene loci. Thirteen loci were found to be polymorphic (frequency of the most common allele 0.95). There was high differentiation between rivers, especially in the southern populations of the Mira and the Arade catchments. This differentiation was associated with a low level of genetic variation and was thus interpreted in the light of past and present bottlenecks. The differentiation of C. lusitanicum is congruent with that already observed for another cyprinid species of the genus Leuciscus inhabiting the same catchments. This reinforces the hypothesis that the periodic drying‐up of extensive sections of these rivers may lead to reduction in population sizes and subsequent differentiation. The level of genetic divergence of both the Mira and Arade populations of C. lusitanicum compared to all other populations sampled suggested a review of their conspecific status is necessary despite morphological similarity. The management implications in these rivers, and in the Tejo and Sado basins where C. lusitanicum is very rare, are discussed.
Hydroacoustic assessment of the fish stock in Theodorushaven, a small Dutch harbour
Authors: KEMPER J.H. , RAAT A.J.P.
Published: November 2003

Assessment of the fish stock in the Theodorushaven was conducted with a dual‐beam hydroacoustic system. Species composition determined by a seine and trawl fishery showed large concentrations of fish in the harbour during winter. The hydroacoustic survey showed that the distribution of fish in the harbour area was stratified with fish near the bottom. The overall density in the harbour area was 0.67 fish m–3. The density in the associated channel area was estimated at 0.1 fish m–3. The coefficient of variation for the estimated total fish abundance was >25%.Fish >25 cm were not caught in the Theodorushaven fishery, although analysis of the sonar data indicated their presence. Fishery data from the adjacent Volkerak‐Zoommeer showed that bream was the dominant species. Therefore, the biomass estimate of the stock >25 cm in the Theodorushaven was based on the standard length–weight relationship of bream. This resulted in maximum biomass estimates of 5800 kg ha–1 for the harbour area and 1100 kg ha–1 in the channel area. The minimum biomass estimate, based on the assumption that the more slender zander was the dominant species >25 cm, gave values of 4100 kg ha–1 in the harbour area and 780 kg ha–1 in the channel area.
A comparison of five external marks for Atlantic salmon, Salmo salar L.
Authors: MOFFETT I.J.J. , CROZIER W.W. , KENNEDY G.J.A.
Published: November 2003

Five external marks (Panjet, visible implant tag, hot brand, anal finclip and fluorescent pigment) were compared for retention and effect on marine survival in Atlantic salmon, Salmo salar L., ranching experiments aimed at complementing coded wire tagging. Only fluorescent pigment marks and Panjet marks were found to be effective, with retention rates of 76.9% and 90.0% respectively, after one year at sea. The Panjet was the only mark to significantly reduce marine survival (P < 0.001) compared with controls.
Diet and feeding relationships of two Iberian cyprinids
Authors: COELHO M.M. , MARTINS M.J. , COLLARES‐PEREIRA M.J. , PIRES A.M. , COWX I.G.
Published: November 2003

The diet and feeding interactions of the Iberian roach, Rutilus alburnoides (Steindachner), and chub, Leuciscus pyrenaicus Günther, were studied in the Sorraia river system. Seasonal shifts in the diets were examined to determine trophic overlap between the two species. Dipteran larvae were the dominant item in the diet of roach with the exception of summer and early autumn when dipteran adults became important. Ephemeroptera nymphs and imagos were the two principal food categories in chub diet. Plant material and terrestrial insects were consumed by both species mostly in the summer and autumn, periods of low availability of aquatic invertebrates in temperate streams. A low dietary overlap was found, probably resulting from differences in their seasonal foraging activity, but also from a compromise between the consumption of highly abundant plant material and rare animal food items.
Dispersion of stocked brown trout, Salmo trutta L., and landlocked salmon, Salmo salar L., from stocking sites in Lake Oulujärvi, Finland
Authors: VEHANEN T. , HYVÄRINEN P. , ASPI J.
Published: November 2003

Movement and recaptures of two hatchery‐reared brown trout, Salmo trutta L., stocks and landlocked salmon, Salmo salar L., released at different sites in regulated Lake Oulujärvi, were studied in relation to release site. Five groups of fish from each stock were released in approximately equal numbers. Most of the fish released in June and July were recaptured within 3 months, whereas the majority of the fish released in early winter (October and November) were caught the following spring, about 7–9 months after stocking. The release site had a significant effect on recapture rate. The results showed that fishing restrictions targeted mainly at gill net fishing are needed to preserve the stocked fish from overfishing. Significantly fewer recaptures were observed from the landlocked salmon stocking compared with brown trout. The recaptures from the landlocked salmon stocking indicated more active movement and less clumping compared with the two brown trout stocks.
Inter‐stage survival of wild juvenile Atlantic salmon, Salmo salar L.
Authors: CUNJAK R. A. , THERRIEN J.
Published: November 2003

A biological model was developed to calculate annual survival between life stages of juvenile Atlantic salmon, Salmo salar L., in Catamaran Brook, a small stream basin (52 km2) in the Miramichi River catchment in New Brunswick, Canada. Seven years’ data (1990–1996) were used in the model. Input variables included: daily fish counts and measurements of parr (3–4 age classes), smolts, and adult salmon at a fish‐counting fence near the stream mouth; biennial quantification of all habitat types along the watercourse; fish density estimated by electric fishing at 30 sites; and estimates of young‐of‐the‐year emigration via stream drift. Continuous recording of stream discharge provided data to assist in interpretation of survival estimates. Annual survival for juvenile salmon in their first 3 years of life in the stream averaged between 31% and 34%. The greatest annual variation (CV = 0.699) occurred at the egg to 0+ (summer) stage with a low of 9.2% survival recorded for a winter with an atypical midwinter flood event; parr and pre‐smolt survival were similarly affected. Survival from egg deposition (after correction for losses caused by predation and retention/non‐fertilization) to smolt emigration was between 0.16% and 0.52%, which is low relative to estimates from many other studies. Survival of smolts to returning 1‐sea‐winter adults (grilse) averaged 8.5%. Potential errors in the computation of the model are discussed, e.g. inaccurate counts of spawning adults during high autumn stream flow. A possible explanation for the low egg to smolt survival was the environmental conditions experienced during various winters. Mean egg survival was 1.3 times higher (39.3%) and egg to smolt survival increased to 1.03% when the two winters characterized by extremely low discharge or midwinter freshets were excluded from the calculation. Density‐dependent factors related to a beaver dam, which limited spawning distribution, may also have contributed to poor survival and increased fry emigration in one year. Environmental factors, particularly winter conditions, in streams such as Catamaran Brook may act as bottlenecks to natural production of Atlantic salmon.
Field sampling design and spatial scale in habitat–hydraulic modelling: comparison of three models
Authors: SCRUTON D. A. , HEGGENES J. , VALENTIN S. , HARBY A. , BAKKEN T. H.
Published: November 2003

Habitat–hydraulic models simulating habitat productive capacity for fish have met with limited success. Limitations of hydraulic modelling, particularly related to spatial scale relevant for hydraulic field data collection and model simulations, have attracted little attention. The hypothesis that hydraulic field sampling procedures and modelling scale per se affect results was tested using three habitat–hydraulic models that employed the same fish habitat data and similar hydraulic models.The PHABSIM, EVHA and HABITAT habitat–hydraulic models were compared on a 5.56 km long, 12–35 m wide, river segment in Newfoundland, Canada. Approaches to hydraulic data collection allowed higher spatial resolution in the EVHA and HABITAT models on selected subsegments representing habitat types (with from 12 to 14 transects per subsegment), while the PHABSIM models covered the entire segment but at lower resolution (a total of 14 transects representing four habitat types placed along the entire segment).Habitat–hydraulic modelling results were similar between the PHABSIM and EVHA with respect to flow vs. suitable habitat curves, but there were important differences between HABITAT and PHABSIM/EVHA. These differences were attributed mainly to different biological models because the hydraulic models performed similarly. Weighted usable area (WUA) curves gave less information than separate suitability curves for habitat variables. It is important that habitat–hydraulic data be collected, and model simulations conducted, at scales that are relevant to habitat selection by species and age classes of interest.
A dynamic model for the life history of Maurolicus muelleri, a pelagic planktivorous fish
Authors: ROSLAND RUNE , GISKE JARL
Published: November 2003

The life history and vertical distribution of a female cohort of the mesopelagic fish Maurolicus muelleri is simulated using stochastic dynamic programming. The environment is represented by vertical profiles of zooplankton biomass, light intensity and temperature, all variables changing with season. The fish physiology is modelled by dynamic state variables that represent structural fish weight, energetic state and the age of developing oocytes. The model is used to simulate optimal depth distribution (feeding vs. predation risk) and energy allocation (somatic growth or reproduction). The optimal strategies predicted by the model depend on structural fish weight, energetic state and seasonal factors in the environment. The different strategies predicted for different size groups of fish are consistent with field observations of M. muelleri. Small fish give higher priority to growth and tolerate higher levels of predation risk than large fish. The strategies of small fish seem to be little affected by changes in energetic state or seasonal factors in the environment. On the other hand, the predicted strategies of large fish are largely dependent on energetic state and seasonal changes in the environment. In the winter they do not reproduce and minimize visual predation risk by staying at depths with a low light intensity. The low light intensities also result in a low food intake and a negative energy budget in the winter months. In spring, summer and autumn, the predicted strategy of large fish is to stay at depths that provide feeding rates sufficient to rebuild energy reserves lost in the winter and to provide energy for reproduction and somatic growth.
Influence of episodic upwelling on capelin, Mallotusvillosus, and Atlantic cod, Gadusmorhua, catches in Newfoundland coastal waters
Authors: INGS D. W. , HORNE J. K. , SCHNEIDER D. C.
Published: November 2003

Wind‐induced upwelling in the north‐west Atlantic has been hypothesized to influence catch rates of fish by gear fishing at fixed locations. Passive movement to shallow depths during upwelling has been proposed to increase encounter rates of fish with net leaders set at the coast. However, supporting evidence is not conclusive, possibly because fish respond to strong events rather than all events. We investigated whether catch rates of capelin, Mallotusvillosus, and Atlantic cod, Gadusmorhua, were related to the strength of upwelling, as measured by the rates of water temperature change, or to stage of upwelling. Capelin trap catches were positively related to increases in water temperature, representing the relaxation phase. This result was due primarily to increases in catch after strong (> 4°C change) rather than after typical (< 4°C change) upwelling events. Cod trap catches were not related to upwelling strength but did increase 1–2 days after typical events. The data suggest that upwelling increases capelin movement, while the return of warmer surface water after an upwelling event increases cod movement.
A continuous, underway fish egg sampler
Authors: CHECKLEY JR DAVID M. , ORTNER PETER B. , SETTLE LAWRENCE R. , CUMMINGS SHAILER R.
Published: November 2003

We describe a method to sample the highly contagious distribution of pelagic fish eggs. CUFES, the continuous, underway fish egg sampler, consists of a submersible pump, concentrator, electronics and sample collector. This system operates continuously and under nearly all sea conditions, providing a real‐time estimate of the volumetric abundance of pelagic fish eggs at pump depth, usually 3 m. CUFES‐derived estimates of volumetric abundance agree well with those from nets towed at pump depth and with areal abundance estimated from vertically integrated plankton tows. CUFES has been used successfully to sample the eggs of menhaden, pinfish, sardine, and anchovy off the coasts of the eastern and western United States and South Africa. Two large patches of eggs of the Atlantic menhaden were sampled off North Carolina in winter 1993–94, had a linear scale of 5–10 km, and were found in waters between the Gulf Stream and mid‐shelf front. Spawning location may be related to bathymetry. CUFES is now being used to estimate spawner biomass by the daily egg production method. An optical plankton counter provided accurate estimates of the number of Atlantic menhaden eggs sample by CUFES.
Spatial structure of co‐occurring anchovy and sardine populations from acoustic data: implications for survey design
Authors: BARANGE MANUEL , HAMPTON IAN
Published: November 2003

A geostatistical analysis has been undertaken on the spatial structure of co‐occurring adult and recruit populations of anchovy, Engraulis capensis, and sardine, Sardinops sagax, in the southern Benguela upwelling region, using information from two acoustic surveys. The study was prompted by the need for a more efficient design for surveying sardine abundance, which is increasing in relation to that of anchovy; the current acoustic survey design is based on the distribution of anchovy. Variograms of fish density and density indicator variables were computed, as well as cross‐variograms between the indicator variables. The sardine variograms were less structured than the anchovy variograms, with slightly greater nugget effects, indicating greater randomness in space at small scales. The indicator variograms showed progressive loss of structure with increasing density. Anchovy formed high‐density schools during the day, breaking into larger, low‐density aggregations at night. Sardine, on the other hand, remained in relatively high‐density schools throughout the day. The cross‐variograms revealed some spatial continuity between low‐ and high‐density areas for anchovy, but no such transitional structures were evident for sardine. It was concluded that sardine are more patchily distributed than anchovy and, unlike anchovy, they may not have a single common way of occupying space at the population level, perhaps partly because of the broader age structure of the population. It is concluded that, while the current acoustic survey design is well suited to the spatial distribution of anchovy, it is not as well suited to that of sardine. Future survey designs should be more tailored to the spatial distribution of sardine, possibly by using sampling methods to cope with the highly patchy distributions expected.