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Morphologic analyses of a large quantity of teudopseid coleoids from the Upper Cretaceous (Cenomanian) of Lebanon has yielded a much higher diversity than previously assumed and revealed numerous extraordinarily well-preserved soft-part characters. The Teudopseina is represented by three families (only the Muensterellidae are still unknown in the Lebanon Plattenkalks). The Teudopsidae is represented by one species (Teudopsinia haasi), the Trachyteuthididae by five species (Trachyteuthis bacchiai n. sp., Glyphiteuthis libanotica, GI. abisaadiorum, GI. frejjii n. sp., and Glyphidopsis waagei n. gen. n. sp.), and the Palaeololiginidae by one species (Rachiteuthis donovani). GI. freijii n. sp. represents the first record of a coleoid cephalopod from Nãmmoura. A detailed comparison with Jurassic gladii shows that the Teudopseina is a very homogenous group that can be easily differentiated from other Mesozoic, gladius-bearing groups (Prototeuthidina, Loligosepiina). Despite comparatively large gaps in the fossil record, each of the Late Cretaceous gladii can be readily associated with Jurassic precursors. Particularly, the first record of two pairs of fins in Glyphiteuthis exemplifies that in addition to gladius similarities, similarities in soft-parts exist as well. A previously undescribed specimen of Rachiteuthis exhibits unusually well- preserved gills. In general, the soft-part morphology of the Teudopseina clearly indicates octobrachiate affinities (i.e., absence of tentacles, circular suckers, cirri, two pairs of fins, octopod-like eye capsules); no existing evidence supports a decabrachiate relationship. [ABSTRACT FROM AUTHOR]

The Modoc sucker received legal protection in the United States based partially on concerns that anthropogenic environmental changes had restricted migration among populations and catalyzed hybridization with a more abundant congener, the Sacramento sucker . We applied eight microsatellite markers to samples of both species collected from two tributaries to the Pit River, California (Ash Creek and Turner Creek), and one tributary of Goose Lake, Oregon (Thomas Creek). Modoc sucker populations in these three tributaries seemed to be largely isolated from one another: gene flow between Ash Creek and Turner Creek was no greater than that among these two creeks and Thomas Creek. In contrast, divergence estimates among collections of Sacramento suckers indicated greater gene flow between Ash Creek and Turner Creek than between either of these creeks and Thomas Creek. Samples collected at a single site (Ash Valley) were identified based on morphology as Modoc suckers, but genetic data suggested they were much more similar to Sacramento suckers. Interspecific hybrids were detected in all three tributaries. Collections of Modoc suckers yielded 0.0--3.9%% hybrids, and collections of Sacramento suckers yielded 0.0--80.0%% hybrids. The two collections with the greatest proportions of hybrids (54.5 and 80.0%%) were both from tributaries to lower Thomas Creek, and neither of these tributaries is thought to have upstream populations of Modoc suckers. Based on 1) low levels of hybrid detection in all three tributaries, 2) the absence of hybrids from typical parental habitats (upstream habitats for Modoc suckers and Pit River mainstem for Sacramento suckers), and 3) highly significant RST (variance in allele size) values between the species, we conclude that hybridization is common but that significant introgression (i.e., loss of parental genotypes) has not occurred. We also note that hybridization, and subsequent introgression, may become a conservation concern in such cases when the habitat of one or both of these species is eliminated or modified. [ABSTRACT FROM AUTHOR]

Abstract: A method is proposed to use naturally occurring radionuclides of the 238U decay series as mass balance tracers to estimate sediment ingestion by benthic fish. The mass balance tracer method can take two forms: one that does not account for tracers that would be ingested in invertebrate food items (simple mass balance tracer method) and one that does (adjusted mass balance tracer method). The contents of the gastrointestinal (GI) tracts from 17 Shorthead Redhorse Suckers (Moxostoma macrolepidotum) were analyzed using the proposed method to determine the proportion of sediment in the fish gut. The proportion of sediment in the GI tract samples was also determined using a method developed by , where the percent soil in wildlife is estimated from the acid insoluble residue (AIR) content of their scat and an assumed level of digestibility of their food (AIR method). The mean mass of sediment in the GI tracts of the 17 fish sampled, calculated using the simple mass balance tracer method, was observed to be 1.14g (standard deviation 0.99g) or approximately 46% (standard deviation 16%) of the dry weight of total GI tract contents. A mean of 0.97g (standard deviation 0.85g), or approximately 38% (standard deviation 13%) of the dry weight of total GI tract contents, was observed when the mass of sediment in the GI tract was calculated using the adjusted mass balance tracer method. When using the AIR method, the mean percentage of sediment in the GI tracts was observed to be 30% (standard deviation 16%). The findings in this study support the assertion that direct ingestion of sediment by benthic fish may be an important pathway for contaminants in aquatic food webs. [Copyright &y& Elsevier]

A growth trial was conducted to estimate the optimum requirement of dietary available phosphorus (P) for Chinese sucker juveniles. Triplicate groups of juveniles Chinese sucker (initial mean weight: 1.77 ± 0.02 g, mean ± SD) were fed diets containing graded levels (3.1, 5.3, 7.5, 9.6 and 11.8 g kg) of available phosphorus. The basal diet (diet 1), containing 3.1 g kg available P, was supplemented with graded levels of monocalcium phosphate to formulate four experimental diets. The fish were fed twice daily (08:00 and 17:00 h) to satiation for 8 weeks. During the experimental period, the water temperature fluctuated from 27.5 to 30.5 °C and dissolved oxygen was more than 6 mg L. The specific growth rate, protein efficiency ratio were all significantly increased by dietary available phosphorus up to 7.5 g kg ( P < 0.05) and then levelled off beyond this level. Feed conversion ratio significantly decreased with dietary available phosphorus level up to 7.5 g kg ( P < 0.05). Dietary treatments did not significantly affect feed intake ( P > 0.05). Efficiency of phosphorus (P) utilization significantly decreased with dietary available phosphorus level ( P < 0.05). Body composition analysis showed that the whole-body lipid, ash, calcium, phosphorus, magnesium (Mg), zinc (Zn) and copper (Cu) contents were all significantly affected by dietary available P concentration ( P < 0.05); however, no significance were found for manganese (Mn) concentration and calcium/phosphorus (Ca/P) ratios in whole-body among all the treatments ( P > 0.05). Dietary phosphorus levels also significantly affected the mineralization of vertebrae and scale ( P < 0.05), and Ca/P ratios in scale were not influenced by dietary P supplementation, while vertebrae Ca/P ratio decreased with dietary available P levels ( P < 0.05) (quadratic effect, P < 0.001). Signs of phosphorus deficiency were characterized by poor growth, slightly reduced mineralization and an increase in body lipid content. The blood chemistry analysis showed that dietary available P had distinct effects on enzyme activities of alkaline phosphatase, as well as contents of triacyglycerol and total cholesterol ( P < 0.05). Broken-line analysis based on weight gain indicated the minimum available phosphorus requirement for the optimal growth of juvenile Chinese sucker was 7.4 g kg. Based on the phosphorus content in whole body, vertebrae or scale indicated that the requirements were 8.3, 8.8 and 8.6 g kg respectively. [ABSTRACT FROM AUTHOR]

Developmental stages of the diplozoid monogenean Eudiplozoon nipponicum, comprising oncomiracidium, diporpa, juvenile, and adult, were investigated using light and scanning electron microscopy in conjunction with confocal scanning laser microscopy in order to examine body organization and identify explicit morphological adaptations to the ectoparasitic life in each stage. The parasite exhibits a complex digestive tract well equipped for hematophagous feeding. It consists of a mouth opening with prominent buccal suckers, eversible pharynx with adjacent glandular structures, and a blind-ending gut with cecal lining. Glandulo-muscular organs, located apically and opened into the mouth corner, are considered to be a part of the digestive tract. Based on our observations of pharynx eversion and in light of the presence of several glandular or gland-like structures, we propose a new hypothesis on the possibility of extracorporeal digestion of this parasite. The hindbody bears an attachment apparatus, comprising haptor, lobular extensions, and tegumental folds, responsible for the parasite's firm attachment to the host gills. The possibility of buccal suckers assisting in the parasite's translocation while searching for an optimal niche or their temporary attachment function during feeding is discussed. The body of each compound adult (i.e., permanent copula) is almost completely filled by two complete reproductive tracts comprising the female as well as male organs. Such a reproductive strategy, in which two independent heterogenic individuals fuse into a single hermaphrodite organism without the need to search for mating partner, represents a high specialization of diplozoids to their parasitic life. [ABSTRACT FROM AUTHOR]

New geographic distribution records are documented for 17 taxa of Arkansas fishes within seven families (Atherinopsidae, Catostomidae, Cyprinidae, Fundulidae, Lepisosteidae, Percidae, Petromyzontidae) from 15 counties of the central and northern portions of the state. Several species are reported from the Eleven Point (Notropis sabinae, Percina evides, Percina sciera and Pereina vigil), Saline (Opsopoeodus emiliae and Fundulus chrysotus), Spring (Moxostoma carinatum), Strawberry (Ichthyomyzon castaneus) and Petit Jean (Ichthyomyzon gagei) river watersheds for the first time. In addition, a new locality in Stone County is added for the endemic and federal candidate species yellowcheek darter (Etheostoma moorei). [ABSTRACT FROM AUTHOR]

We resurrect Catostomus tsiltcoosensis, the Tyee sucker of Oregon coastal rivers, from the synonymy of Catostomus macrocheilus and compare it with its congeners. Catostomus tsiltcoosensis is superficially similar to disjunctly distributed Catostomus occidentalis of the Sacramento drainage and Catostomus ardens of the Upper Snake River and Bonneville Basin. However, the gill raker structure, wide frontoparietal fontanelle, location of the ninth cranial foramen, scale radii patterns, and cytochrome b sequences clearly align C. tsiltcoosensis with C. macrocheilus rather than C. occidentalis. Differences in counts of infraorbital pores and dorsal fin rays, in body depth proportions, and in cytochrome b sequences distinguish C. tsiltcoosensis and C. macrocheilus. Within C. tsiltcoosensis, specimens from each of the 4 main drainages (north to south-Siuslaw, Umpqua, Coos, and Coquille) were reciprocally monophyletic based on cytochrome b data but showed no differences in the morphological features examined. Both C. tsiltcoosensis and another Oregon coastal taxon Catostomus rimiculus were paraphyletic based on cytochrome b. Although such discordant mitochondria results can be due to introgression, incomplete lineage sorting, and paralogy, other evidence suggests that introgression and lateral transfer of mitochondria explains the cytochrome b pattern in C. rimiculus. We speculate that lateral transfer might also be responsible for the pattern in C. tsiltcoosensis, except that the Coquille River population appears not to have been included in recent transfers. [ABSTRACT FROM AUTHOR]

We assessed the efficacy of passive gravel addition at forming catostomid spawning habitat under various flow regimes in the Cheoah River, a high-gradient tailwater river in North Carolina. The purpose was to provide a case study that included recommendations for future applications. A total of 76.3 m3 (162 tons) of washed gravel (10-50 mm) was passively dumped down the streambank and into the channel in four locations. Gravel sites differed in terms of average reach slope, bank slope, and the initial volume of gravel added, which could have influenced gravel entrainment. Maps of gravel movement under various flows suggested that large-magnitude discharges (≥113 m3/s) caused extensive migration; however, less obvious, smaller discharges (~28 m3/s) still caused substantial shifting, which may influence the stability of catostomid spawning substrates. Following gravel addition, the proportion of gravel in the streambed was significantly higher at all gravel sites. However, comparisons of sites to reference stream reaches suggested that sand, gravel, and cobble were still extremely deficient. Additionally, the volume of gravel was inadequate to create gravel depths that provided suitable habitat for catostomid spawning. Although periodic, passive gravel additions may take years to provide suitable spawning habitat for some fish species, we found that river chub utilized the newly added gravel for spawning. [ABSTRACT FROM AUTHOR]

Kreitzer JD, Belk MC, Gonzalez DB, Tuckfield RC, Shiozawa DK, Rasmussen JE. Ontogenetic diet shift in the June sucker Chasmistes liorus (Cypriniformes, Catostomidae) in the early juvenile stage. Ecology of Freshwater Fish 2010: 19: 433–438. © 2010 John Wiley & Sons A/S Ontogenetic diet shifts are common in fishes and often occur during early life stages. The larval and early juvenile period is critical in the life cycle of the endangered June sucker, Chasmistes liorus (Teleostei: Catostomidae). High larval and juvenile mortality leads to low recruitment to the breeding population and hence a declining natural population. To understand diet composition and dynamics in June sucker at early life stages, diet was quantified and compared to available food items in the natural environment during the early juvenile stage. Rotifers ( Brachionus sp.) were the primary diet item at week 10, but by week 12 a small cyclopoid copepod ( Microcyclops rubellus) became predominant. Availability of diet items varied little across the experimental period. The increase in size of young suckers may explain this rapid dietary shift, but there are some inconsistencies with the size selection argument. This diet shift represents an important nutritional change that should be considered in development of diets for young June sucker and in assessing suitability of nursery habitats. [ABSTRACT FROM AUTHOR]

Abstract: Building a reliable database on apparent digestibility of protein sources is critical for accurate feed formulation and reduction of aquaculture wastes. Apparent digestibility coefficients (ADCs) of dry matter (DM), crude protein, crude lipid, gross energy, phosphorus and amino acids for white fish meal (WFM), brown fish meal (native) (BFM), fermented soybean meal (FSBM), extruded soybean meal (ESBM), soybean meal (SBM), cottonseed meal (CM) and rapeseed meal (RM) were determined for Chinese sucker (Myxocyprinus asiaticus) (18.05±0.27g) using a reference diet (RF) and test diets (70% RF diet plus 30% of tested feedstuff) containing 0.5% chromic oxide as an inert marker. WFM had the highest apparent digestibility coefficient for DM (74.5%). For plant products, the ADCs of DM ranged from 54.3 to 71.6%. Protein digestion by Chinese sucker of WFM, BFM, FSBM and ESBM was significantly higher than CM and RM, ranging from 72.8 to 92.3% for plant products, and 90.3 to 91.2% for animal feedstuffs. Lipids from both animal and plant feedstuffs were highly digested by Chinese sucker, ranging from 89.8 to 94.9%. The highest digestibility coefficient of energy was registered for WFM, followed by BFM; and the lowest digestibility coefficient of energy was recorded for CM (P <0.05). The Chinese sucker did utilize dietary phosphorus from the animal feedstuffs (FSBM and ESBM) more efficiently than from plant feedstuffs (SBM, CM and RM), with values ranging from 58.8 to 61.4% and 25.8–56.0%, respectively. Amino acid availability reflected protein digestibility, except for ESBM, for which the availability of some amino acids was lower, possibly because of protein denaturation during processing. Based on the current findings, FSBM and ESBM could be considered as good potential substitutes for FM in diets for Chinese sucker. [Copyright &y& Elsevier]

Abstract: Buffalofishes (Genus Ictiobus) are large, robust-bodied suckers adapted to large rivers and lakes of North America. Currently recognized species are readily diagnosed by morphological characters, and the group is known from fossils dating back to the Miocene. However, sympatrically occurring species in the Mississippi River Basin are known to hybridize in nature and in the laboratory. Here we describe patterns of morphological (morphometric) and DNA sequence variation (mitochondrial and nuclear genes) across the geographic ranges of extant species of genus Ictiobus. We show that Ictiobus species form more of less discrete entities based on body morphometry, consistent with current taxonomy. However, except for I. labiosus, there is extensive sharing of alleles of nuclear and mitochondrial genes among species, and the species do not form reciprocally monophyletic groups in nuclear or mitochondrial gene trees. Moreover, the pattern is not confined to the broad area of sympatry in the Mississippi River Basin. We attribute this to a long history of introgressive hybridization and gene flow among species inhabiting the present-day Mississippi River Basin, and recent colonization of the Great Lakes, Hudson Bay drainage and gulf coastal rivers east and west of the Mississippi River by introgressed Mississippi River Basin stocks. [Copyright &y& Elsevier]

We examined between-reader precision of age estimates of scales and pectoral fin rays for 123 highfin carpsuckers (Carpiodes velifer), 174 quillback carpsuckers (C. cyprinus), and 135 river carpsuckers (C. carpio). Precision of age estimates was assessed through measures of agreement, the coefficient of variation (CV), and a confidence rating. Exact agreement between readers was higher for fin rays (highfin carpsucker = 82.1%; quillback carpsucker = 75.9%; river carpsucker = 77.0%) than scales (highfin carpsucker = 69.5%, quillback carpsucker = 68.9%; river carpsucker = 71.1%). In addition, CV was lower for fin rays (highfin carpsucker = 2.28; quillback carpsucker = 2.43; river carpsucker = 2.90) than scales (highfin carpsucker = 2.95; quillback carpsucker = 3.00; river carpsucker = 3.46). Fin rays were also assigned a higher confidence rating (i.e., mean readability, 0-3 with 3 being high; highfin carpsucker = 2.22; quillback carpsucker = 1.95; river carpsucker = 1.92) than scales (highfin carpsucker = 1.53; quillback carpsucker = 1.51; river carpsucker = 1.68). [ABSTRACT FROM AUTHOR]

Resource selection analyses of telemetry data are often conducted on categorical measurements of use and availability. Refinement of early resource selection analysis techniques has resulted in use of individuals as the sample unit rather than the number of telemetry detections. However, the minimum number of telemetry detections required for an individual animal to be included as a sample unit must reflect the number of detections needed to accurately describe the individual's resource use. We developed a method to determine the minimum number of detections required to accurately describe categorical resource use of an animal. The mean standard selection ratio (MSSR) described herein can be used to effectively design telemetry projects and efficiently allocate field resources by knowing, a priori, the number of telemetry detections needed to explain resource selection for individual animals and ultimately for an animal population. Additionally, the MSSR technique can be used following data collection to determine the detection level needed for inclusion of individuals in categorical resource selection analyses. [ABSTRACT FROM AUTHOR]

Models for capture-recapture data are commonly used in analyses of the dynamics of fish and wildlife populations, especially for estimating vital parameters such as survival. Capture-recapture methods provide more reliable inferences than other methods commonly used in fisheries studies. However, for rare or elusive fish species, parameter estimation is often hampered by small probabilities of re-encountering tagged fish when encounters are obtained through traditional sampling methods. We present a case study that demonstrates how remote antennas for passive integrated transponder (PIT) tags can increase encounter probabilities and the precision of survival estimates from capture-recapture models. Between 1999 and 2007, trammel nets were used to capture and tag over 8,400 endangered adult Lost River suckers (Deltistes luxatus) during the spawning season in Upper Klamath Lake, Oregon. Despite intensive sampling at relatively discrete spawning areas, encounter probabilities from Cormack-Jolly-Seber models were consistently low (< 0.2) and the precision of apparent annual survival estimates was poor. Beginning in 2005, remote PIT tag antennas were deployed at known spawning locations to increase the probability of re-encountering tagged fish. We compare results based only on physical recaptures with results based on both physical recaptures and remote detections to demonstrate the substantial improvement in estimates of encounter probabilities (approaching 100%) and apparent annual survival provided by the remote detections. The richer encounter histories provided robust inferences about the dynamics of annual survival and have made it possible to explore more realistic models and hypotheses about factors affecting the conservation and recovery of this endangered species. Recent advances in technology related to PIT tags have paved the way for creative implementation of large-scale tagging studies in systems where they were previously considered impracticable. [ABSTRACT FROM AUTHOR]

Some fishes use modified body structures – including pelvic fins – to produce suction to facilitate stability in turbulent environments. This study compares the morphology and osteology of the pelvic suckers of representative lumpfishes (Cyclopteridae), snailfishes (Liparidae) and gobies (Gobiidae). In all species studied the midline sucker (pelvic suctorial organ [PSO]) is formed from the pelvic girdle and fin rays I and 5 of the pelvic fins, comprised of similar osteological elements to those found in the pelvic girdle and pelvic fin rays although the morphology of the bony elements is species-specific. Pelvic suctorial organs in those fishes that lack pelvic girdles are therefore homologous to pelvic girdles. The phenotypic diversity seen in so few species indicates that many sucker morphologies have arisen, origination depending on the concerted development of muscular, skeletal, nervous, and skin body tissues. The structure of the soft rays of the pelvic fins in the liparids and cyclopterids is unusual and indicative of unconventional developmental patterning of fin ray halves and of evolution in the underlying mechanisms responsible for the development of midline suckers. [ABSTRACT FROM AUTHOR]

Stream fish managers often use fish sample data to inform management decisions affecting fish populations. Fish sample data, however, can be biased by the same factors affecting fish populations. To minimize the effect of sample biases on decision making, biologists need information on the effectiveness of fish sampling methods. We evaluated single-pass backpack electrofishing and seining combined with electrofishing by following a dual-gear, mark-recapture approach in 61 blocknetted sample units within first-to third-order streams. We also estimated fish movement out of unblocked units during sampling. Capture efficiency and fish abundances were modeled for 50 fish species by use of conditional multinomial capture-recapture models. The best-approximating models indicated that capture efficiencies were generally low and differed among species groups based on family or genus. Efficiencies of single-pass electrofishing and seining combined with electrofishing were greatest for Catostomidae and lowest for Ictaluridae. Fish body length and stream habitat characteristics (mean cross-sectional area, wood density, mean current velocity, and turbidity) also were related to capture efficiency of both methods, but the effects differed among species groups. We estimated that, on average, 23% of fish left the unblocked sample units, but net movement varied among species. Our results suggest that (1) common warmwater stream fish sampling methods have low capture efficiency and (2) failure to adjust for incomplete capture may bias estimates of fish abundance. We suggest that managers minimize bias from incomplete capture by adjusting data for site- and species-specific capture efficiency and by choosing sampling gear that provide estimates with minimal bias and variance. Furthermore, if block nets are not used, we recommend that managers adjust the data based on unconditional capture efficiency. [ABSTRACT FROM AUTHOR]

Telemetry data were used to quantify seasonal resource selection and rank-preferred habitat types for blue suckers Cycleptus elongatus in the middle Missouri River and its tributaries, Iowa, Nebraska, South Dakota, U.S.A. Habitat diversity required by C. elongatus to complete its annual life-history cycle was evident by interseasonal variation in habitat selection. Tributaries and unchannelized portions of the middle Missouri River system were selected during the inferred spawning season (spring), habitats along shorelines in the channelized middle Missouri River were selected for postspawning (summer) and areas of reduced current were generally selected for the period preceding spawning (autumn). This study provides insight into mature C. elongatus behaviour throughout its annual life cycle. Furthermore, these results document the interseasonal variability in habitat selection of C. elongatus and highlight the need for development of habitat selection models for other imperilled fish species in aquatic systems affected by anthropogenic developments. [ABSTRACT FROM AUTHOR]

Catostomid fishes (suckers) have duplicate copies of the growth hormone gene and other nuclear genes, due to a genome duplication event early in the group's history. Yet, paralogs of GH in suckers are more than 90% conserved in nucleotide (nt) and amino acid (aa) sequence. Within paralogs across species, variation in nt and aa sequence averages 3.33% and 4.46% for GHI, and 3.22% and 2.43% for GHII, respectively. Selection tests suggest that the two GH paralogs are under strong purifying selection. Consensus trees from phylogenetic analysis of GH coding region data for 23 species of suckers, other cypriniform fishes and outgroups resolved cypriniform relationships and relationships among GHI sequences of suckers more or less consistently with analyses based on other molecular data. However, the analysis failed to resolve all sucker GHI and GHII sequences as monophyletic sister groups. This unexpected topology did not differ significantly from topologies constrained to make all GH sequences monophyletic. We attribute this result either to limitations in our GHII data set or convergent adaptive changes in GHII of tribe Catostomini. [ABSTRACT FROM AUTHOR]

We document the discovery of Highfin Carpsucker in the Apalachicola River, FL. Three specimens were captured between river kilometer 170-171 on the Apalachicola River in the vicinity of Jim Woodruff Lock and Dam during spring 2007. The specimens were captured within a reach 0.5-1.0 km downstream from the dam and just upstream from a major spawning area for several other catostomids. This is the first record of the species east of the Choctawhatchee River, FL-AL, and is a range extension of 185 km eastward into the Florida Panhandle region of the Northern Gulf of Mexico Coast. [ABSTRACT FROM AUTHOR]

Abstract: Family Catostomidae is a diverse group of benthic freshwater fishes that are distributed across North America and in parts of East Asia. In this study, the phylogenetic relationships of Catostomidae is examined using 3436 nucleotides of mitochondrial ND4 and ND5 protein coding genes and intervening tRNAs. All 13 genera and 60 species of catostomids were sampled to represent diversity of the family. Catostomidae and its four subfamilies were found to be monophyletic; however, relationships of the subfamilies are not strongly supported with bootstrapping. The analysis provides strong support for recognizing four tribes in subfamily Catostominae. [Copyright &y& Elsevier]

Factors affecting the early life survival of fishes are often difficult to demonstrate because variable immigration and mortality rates coupled with noncontinuous sampling may confound estimates of mortality and bias inference to more numerous smaller individuals. The larval production estimate (LPE) method eliminates these problems by compensating catch data for size- or age-specific mortality and growth and back-calculating abundance at a predetermined size or age. Despite its utility, LPE has not been widely applied in studies of freshwater fish recruitment. We executed an LPE analysis using 10–14 mm and 15–19 mm size classes of Upper Klamath Lake’s (UKL) endangered Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) for five cohorts per year for 1995–2001. Larval survival peaked when habitat conditions included high availability of emergent macrophytes as habitat (>15 000 m3), air temperatures between 14 and 22 °C, and a low frequency of wind speeds >16 km·h–1. Age-0 juvenile suckers collected later in each year corroborated results of the LPE analysis, as most (88%) juveniles had otolith-estimated swim-up dates corresponding to early life rearing under the specified habitat conditions. Our results support the management practice of maintaining higher than natural UKL water surface elevations through the larval rearing period. [ABSTRACT FROM AUTHOR]

Robust redhorse ( Moxostoma robustum) is a rare riverine sucker for which life history information is scarce. Spawning occurs over loose gravel substrate and eggs and larvae may be adversely affected by fine sediments among the gravel. A 2-year study was conducted to determine the threshold at which fine sediments are detrimental to successful egg incubation and larval emergence. Year 1 gravel treatments contained 0, 25, 50, and 75% fine sediments. Mean survival during Year 1 ranged from 63.5% in the 0% fine sediment treatment to 0% in the 75% fine sediment treatment. The results also indicated an adverse affect threshold between 0 and 25% fine sediment. Year 2 gravel treatments contained 0, 5, 10, 15, 20, and 25% fine sediments. Mean survival during Year 2 ranged from 69.8% in the 0% treatment to 9.1% in the 25% treatment. Year 2 results also identified the 15% fine sediment treatment as the threshold at which survival began to decline. Substrates at one known spawning area used by robust redhorse typically contain 25 to 50% fine sediment, but the spawning act cleans some fines from the egg pocket. Whether the “cleaning” that results from the spawning act reduces the fines sufficiently to avoid adverse effects is unknown. According to our results, survival rates of robust redhorse eggs and larvae are predicted to be about 8.0% or less when fine sediment is >25%. [ABSTRACT FROM AUTHOR]

Specific scope This standard describes the conduct of trials for the efficacy evaluation of plant growth regulators used to control suckers in Rubus. It refers to the control of unwanted suckers growing in the alleyways between rows or between stools (hills) within the row. The principal requirement is to remove sucker growth without drift or translocation of the chemical agent to the parent plant. Specific approval and amendment First approved in 1990–09. Revision approved in 2009–09. [ABSTRACT FROM AUTHOR]

The silver redhorse Moxostoma anisurum is listed as threatened and considered critically imperiled (S1) in Arkansas by the Nature Conservancy. Only 12 records comprising 23 specimens of this species from five rivers are known from the state. A recent record is from the Strawberry River in Lawrence County during 2007; it and other records in Arkansas are reviewed. In 2007, 26 species of fish were collected with the silver redhorse, including the first vouchered specimens of the pealip redhorse Moxostoma pisolabrum and the pallid shiner Hybopsis amnis from the Strawberry River. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the dietary protein requirement for juvenile Chinese sucker, Myxocyprinus asiaticus. Six fishmeal-based experimental diets containing various crude protein levels ranging from 300 to 500 g kg−1 were fed to triplicate groups of 20 fish each (initial weight 13.5 ± 1.1 g) for 56 days at a temperature of 28 ± 1°C (tank size 400 × 45 × 40 cm, linked to a recirculation system). Survival was not affected by dietary protein level (overall survival 71 to 90%). Weight gain (WG) and specific growth rate (SGR) increased with an increasing dietary protein level up to 460 g kg−1. The feed conversion rate (FCR) generally showed a decline at higher protein levels (from 1.62 in 300 g protein kg−1 to 1.13 in 500 g protein kg−1 feed). Protein efficiency ratio (PER) showed gradual improvements with increasing dietary protein up to 460 g kg−1. A similar trend was found for the protein productive value (PPV). Among the proximate compositions of the fish, crude protein content increased significantly with increasing dietary protein levels. Based on broken-line regression analysis of SGR against dietary protein levels, the optimal dietary protein requirement for juvenile Chinese sucker was estimated to be close to 465 g kg−1. [ABSTRACT FROM AUTHOR]

Efforts to understand the effects of environmental estrogens on fish have shifted away from biochemical indicators towards population-level impacts. Ethynylestradiol (EE2) was added to a whole lake at environmentally relevant concentrations for 3 consecutive years to examine links between vitellogenin (VTG) induction, histopathological impacts, and population decline in four species of fish. VTG induction and histopathological effects in tissues were most severe in fathead minnow (Pimephales promelas) and pearl dace (Margariscus margarita). VTG was induced to a similar extent in lake trout (Salvelinus namaycush) but less so in white sucker (Catostomus commersonii). There were no histopathological effects in tissues of the two latter species. Population decline occurred in fathead minnows in the second year of EE2 additions and there were some indications of population decline in pearl dace during the third year. White suckers were not affected but lake trout declined in year 3. Habitat selection probably altered EE2 exposure and the different effects in each species likely also reflect differing sensitivities. It appears that VTG induction is not sufficient to predict effects of xenoestrogens on fish populations. However, stronger predictions can be made when VTG induction is assessed in conjunction with histopathological evidence of liver, kidney, and gonad tissue damage. [ABSTRACT FROM AUTHOR]

The transcription factors Apterous/Lhx2/9 play many pivotal roles in the development of protostomes and deuterostomes, most notably limb patterning, eye morphogenesis, and brain development. Full-length apterous/lhx2/9 homologs have been isolated from several invertebrate species, but hitherto not from a lophotrochozoan. Here, we report the isolation, characterization, and spatio-temporal expression of apterous in the sepiolid squid Euprymna scolopes. The isolated composite cDNA encodes a hypothetical protein of 448 amino acid residues with a typical LIM-homeodomain (LIM-HD) structure and the greatest overall sequence similarity to vertebrate Lhx2/9 proteins. The Euprymna scolopes apterous ( Es-ap) expression patterns provided no indication of a role in the early dorso/ventral patterning or growth of the arm crown that showed expression only in two ventral cords running in parallel inside the arms and tentacles and at the base of the suckers, a region rich in nerve endings and chemosensory neurons. The Es-ap hybridization signal was also conspicuous in the eyes, olfactory organs, optic lobes, and in several lobes of the supraesophageal mass, among these the olfactory and vertical lobes, and paravertical bodies. The observed expression patterns suggest gene involvement in eye morphogenesis and neural wiring of sensory structures, including those for olfaction and vision. [ABSTRACT FROM AUTHOR]

The article discusses a study on Falcaustra manouriacola n. sp. from the large intestine of impressed tortoise. The F. manouriacola is identified from other Oriental species through the distribution pattern of the caudal papillae. Nematodes were found in the large intestine of the tortoise which were the cause of their severe illness and death. The study found that the structure of the esophagus of F. manouriacola n. sp. has a spherical isthmus behind the esophageal bulb.

Vitellogenin (VTG), the egg yolk precursor protein, was purified from plasma of estradiol-3-benzoate (E2B)-treated male shorthead redhorse ( Moxostoma macrolepidotum) and immature copper redhorse ( Moxostoma hubbsi) by a two-step chromatographic procedure without precipitation. Intact VTGs appeared as dimers with apparent molecular masses, determined by gel filtration, of ∼425 kDa (copper redhorse) and ∼450 kDa (shorthead redhorse). In native polyacrylamide gel electrophoresis (PAGE), dimeric redhorse VTGs appeared as a 520 kDa band. Both VTGs were reduced to a single monomer of ∼150 kDa in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing and nonreducing conditions, indicating that monomers are not linked by disulfide bonds in the dimer form. The purified proteins were characterized as phospholipoglycoproteins. Isoelectric focusing of both VTGs revealed components with isoelectric points ranging from 5.3 to 6.0, suggesting charge heterogeneity. The amino acid composition of both VTGs contains a high proportion of nonpolar amino acids and was similar to those of other teleosts. An antibody developed against carp ( Cyprinus carpio) VTG showed cross-reactivity with VTG from both redhorse species. Using this antibody, VTG was detected in plasma and surface mucus of E2B-treated redhorse. This is the most extensive report on purification and characterization of vitellogenin from catostomidid species. [ABSTRACT FROM AUTHOR]

To assess the effect of agriculture drain water, a complex mixture containing pesticides and selenium (Se), on the physiological stress response, white suckers were collected from irrigation return flows in the summer and the fall and subjected to a stress challenge. Water (0.40–26.71μg/L) and muscle Se (0.37–1.52μg/g ww) levels were elevated at two sites and plasma acetylcholinesterase (AChE) activity (a marker of pesticide exposure) was lower in the fall (5.97±0.45μmol/min/mL) than the summer (10.73±0.73μmol/min/mL). Fish raised plasma cortisol levels in response to the stress challenge 11.8 times above basal levels (12.8±4.9ng/mL). Multivariate statistics linked Se exposure to elevated plasma glucose levels, and pesticide exposure to elevated liver glycogen levels generating hypotheses for further testing. This study showed that white suckers accumulated Se from agricultural drain water and the complex mixtures present in the drain water influenced the physiological stress response. [Copyright &y& Elsevier]

Lead (Pb) and other metals can accumulate in northern hog sucker ( Hypentelium nigricans) and other suckers (Catostomidae), which are harvested in large numbers from Ozark streams by recreational fishers. Suckers are also important in the diets of piscivorous wildlife and fishes. Suckers from streams contaminated by historic Pb–zinc (Zn) mining in southeastern Missouri are presently identified in a consumption advisory because of Pb concentrations. We evaluated blood sampling as a potentially nonlethal alternative to fillet sampling for Pb and other metals in northern hog sucker. Scaled, skin-on, bone-in “fillet” and blood samples were obtained from northern hog suckers ( n = 75) collected at nine sites representing a wide range of conditions relative to Pb–Zn mining in southeastern Missouri. All samples were analyzed for cadmium (Cd), cobalt (Co), Pb, nickel (Ni), and Zn. Fillets were also analyzed for calcium as an indicator of the amount of bone, skin, and mucus included in the samples. Pb, Cd, Co, and Ni concentrations were typically higher in blood than in fillets, but Zn concentrations were similar in both sample types. Concentrations of all metals except Zn were typically higher at sites located downstream from active and historic Pb–Zn mines and related facilities than at nonmining sites. Blood concentrations of Pb, Cd, and Co were highly correlated with corresponding fillet concentrations; log–log linear regressions between concentrations in the two sample types explained 94% of the variation for Pb, 73–83% of the variation for Co, and 61% of the variation for Cd. In contrast, relations for Ni and Zn explained <12% of the total variation. Fillet Pb and calcium concentrations were correlated ( r = 0.83), but only in the 12 fish from the most contaminated site; concentrations were not significantly correlated across all sites. Conversely, fillet Cd and calcium were correlated across the range of sites ( r = 0.78), and the inclusion of calcium in the fillet-to-blood relation explained an additional 12% of the total variation in fillet Cd. Collectively, the results indicate that blood sampling could provide reasonably accurate and precise estimates of fillet Pb, Co, and Cd concentrations that would be suitable for identifying contaminated sites and for monitoring, but some fillet sampling might be necessary at contaminated sites for establishing consumption advisories. [ABSTRACT FROM AUTHOR]

Developmental constraints and selective pressures interact to determine the strength of allometric scaling relationships between body size and the size of morphological traits among related species. Different traits are expected to relate to body size with different scaling exponents, depending on how their function changes disproportionately with increasing body size. For trematodes parasitic in vertebrate guts, the risk of being dislodged should increase disproportionately with body size, whereas basic physiological functions are more likely to increase in proportion to changes in body size. Allometric scaling exponents for attachment structures should thus be higher than those for other structures and should be higher for trematode families using endothermic hosts than for those using ectotherms, given the feeding and digestive characteristics of these hosts. These predictions are tested with data on 363 species from 13 trematode families. Sizes of four morphological structures were investigated, two associated with attachment (oral and ventral suckers) and the other two with feeding and reproduction (pharynx and cirrus sac). The scaling exponents obtained were generally low, the majority falling between 0.2 and 0.5. There were no consistent differences within families between the magnitude of scaling exponents for different structures. Also, there was no difference in the values of scaling exponents between families exploiting endothermic hosts and those using ectotherms. There were strong correlations across families between the values of the scaling exponents for the oral sucker, the ventral sucker and the pharynx: in families where the size of one trait increases relatively steeply as a function of body size, the same is generally true of the other traits. These results suggest either that developmental constraints link several morphological features independently of their specific roles or that similar selection pressures operate on different structures, leading to covariation of scaling exponents. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 533–540. [ABSTRACT FROM AUTHOR]

The article explores the post-release movements and habitat use of robust redhorse which are transplanted to the Ocmulgee River in Georgia. It examines the effectiveness of stocking programmes aimed to recover robust redhorse. The recovery efforts focus on supplementing existing populations and creating refugial populations and use radio telemetry to evaluate the programmes' effectiveness. The efficacy of a stocking programme is claimed to depend on the ability of stocked individuals to integrate into an existing population.

Effects of water temperature, starvation and photoperiod on otolith increment formation in larval Chinese sucker, Myxocyprinus asiaticus, were examined in this study. The results demonstrated that otolith increments of larvae reared under diel temperature fluctuations were very clear and appeared with a high contrast, while those of larvae raised under constant water temperatures were vague or hard to identify. The increment deposition rates were less than 1.0/day in later stage of starvation period. Also, increment deposition was affected by cyclic regimes of water temperature fluctuations, the number of increments corresponded to the cycle times rather than the exact days larvae experienced. However, varying of feeding frequency and photoperiod did not result in any alterations of daily increment formation. Increment width increased obviously with higher rearing temperatures till several days after yolk absorption. However, the width presented an ontogenetic decline during period of endogenous nutrition and the first several days of exogenous nutrition stage. Starvation decoupled the relationship between somatic growth and otolith growth; otolith kept growing, and increment width of starved larvae was similar to those in fed individuals before 9–20 days old; the divergence of increment width from the fed larvae occurred in later stage of starvation period. It can be concluded that temperature regimes and food levels are the major factors affecting increment formation in terms of clarity, deposition rate and width, while photoperiod and feeding frequency have less influence on it. [ABSTRACT FROM AUTHOR]

Population decline in the federally endangered June sucker ( Chasmistes liorus), a lakesucker unique to Utah Lake, Utah, has been attributed in part to hybridization with the more widespread Utah sucker ( Catostomus ardens). As a group, suckers in Utah Lake exhibit considerable external morphological variation. Meristic and morphological ambiguities, presumably the result of hybridization, create a continuum of intermediate forms between Chasmistes and Catostomus extremes and prevent definitive identification to species. Here we describe and evaluate the morphological and genetic variation in suckers in Utah Lake by comparing a morphological analysis with amplified fragment length polymorphism and microsatellite analyses. Suckers were morphologically differentiated using mouth characters associated with different feeding strategies: planktivory (June sucker) and benthivory (Utah sucker). Although we found no genetic evidence for a deep divergence between June and Utah morphs, significant, but slight population structuring accompanied the substantial morphological variation. Bayesian model-based genetic clustering analyses detected two sucker populations in Utah Lake; however, these clusters were not strongly concordant with morphological groupings or between marker systems. The suckers in Utah Lake present an interesting dilemma regarding conservation: should one conserve (breed and stock) a subset of the morphotypic variation in the Utah Lake sucker complex, focusing on the endangered June sucker morphotype, or should one conserve both June sucker and Utah sucker morphotypes in this complex, possibly maximizing evolutionary potential? We explore this question in the context of current genetic and morphological variation in the Utah Lake sucker complex as well as historical information on this complex and other lakesuckers. [ABSTRACT FROM AUTHOR]

An understanding of the proportion of true seedlings, seedling sprouts and root suckers in the forest is essential for directing the genetic composition of the future crop. We conducted a study to determine the difference between these plantlets of Detarium microcarpum based on morphological characters and carbohydrate contents in leaves and roots. For individuals ≤50 cm in height, root suckers had the highest values for height, stem length, internode number, root diameter, rachis length and leaflet number. The concentrations of starch and total nonstructural carbohydrates in the roots of seedling sprouts were superior. Plantlets did not differ in the concentration of leaf carbohydrates. For individuals >50 cm in height, root suckers had larger values for stem length, root diameter, leaflet length and width. Roots of seedling sprouts showed higher concentrations of soluble sugars and total soluble sugars. True seedlings were distinguished from seedling sprouts and root suckers using all morphological traits except collar diameter and leaflet number. Root suckers and seedling sprouts showed a closer morphological resemblance; thus resulted in slightly more than 50% discrimination success. In conclusion, discrimination between seedling sprouts and root suckers appeared to be more difficult than between true seedlings and clonal plantlets. [ABSTRACT FROM AUTHOR]

Efforts to protect or rehabilitate depressed blue sucker Cycleptus elongatus populations require an understanding of life-history characteristics and reproductive biology to provide fisheries managers with the tools required for science-based management. The objective of this study was to examine the reproductive biology of blue sucker in the Wabash River, Indiana, during March and April 2006. A total of 105 reproductively mature blue sucker (53 males, 52 females) was collected using boat electrofishing to examine size-at-maturity, absolute fecundity, gonadosomatic index (GSI), relative fecundity, and estimated egg size. Size-at-maturity was estimated at 515 mm total length (TL) for males and 568 mm TL for females. Mean absolute fecundity of females captured during the study was 150 704 eggs per female (range, 26 829–267 471 eggs per female) and was positively related to both TL ( r 2 = 0.66) and wet weight ( r 2 = 0.77). Mean GSI was 6.4% (range, 2–9.3%) for males and 17.2% (range, 4.3–23.4%) for females. Relative fecundity ranged from 15 331 to 65 887 eggs kg−1 body weight (mean = 46 946 eggs kg−1 body weight) and was strongly correlated with GSI ( r 2 = 0.87). Mean estimated egg size was 278 eggs g−1 (range, 229 364 eggs g−1) and exhibited an inverse relationship to GSI ( r 2 = 0.42). The results of our study provide information on the reproductive biology of blue sucker which can be used to aid in the identification of potential recovery threats for depressed populations. [ABSTRACT FROM AUTHOR]

Differences in the life history strategies employed by otherwise ecologically similar species of a fish assemblage may be an important factor in the coexistence of these species and is an essential consideration in the conservation and management of these assemblages. We collected scales to determine age and growth of four species of the catostomid assemblage (northern hogsucker Hypentelium nigricans, spotted sucker Minytrema melanops, notchlip redhorse Moxostoma collapsum and robust redhorse Moxostoma robustum) of the Savannah River, Georgia–South Carolina in spring 2004 and 2005. Robust redhorse was the largest species; reaching sexual maturity at an older age and growing faster as a juvenile than the other species. Spotted sucker did not achieve the same size as robust redhorse, but reached sexual maturity at younger ages. Notchlip redhorse was intermediate between the abovementioned two species in age at maturity and size. Northern hogsucker was the smallest species of the assemblage and reached the sexual maturity at the age of three. Both robust redhorse and spotted sucker were sexually dimorphic in size-at-age. The range of life history strategies employed by Savannah River catostomids encompasses the range of life history strategies exhibited within the family as a whole. [ABSTRACT FROM AUTHOR]

Gynaecotyla squatarolae (Digenea: Microphallidae) adult flukes were recovered from experimental chicks at day 4-6 post-infection and their tegumental ultrastructure was observed with a scanning electron microscopy. They were pyriform in shape, and their anterior halves were concaved ventrally. The whole body surface was covered with tegumental spines, which were wide and 16-17 digitated between oral and ventral suckers. The density of spines and number of digits decreased posteriorly. The oral sucker was subterminal and the excretory pore was at the posterior end of the worm. Two ventral suckers were similar in appearance and protruded near midline of the worm. The genital atrium was dextral to the small ventral sucker. The dorsal surface was covered with tegumental spines, but the spines were sparser than on the ventral surface. On the middle portion of the dorsal surface, a small opening presumed to be the Laurer's canal was seen. From these findings, it has been confirmed that the adult G. squatarolae has unique characteristics in the surface ultrastructure. [ABSTRACT FROM AUTHOR]

Holostephanus metorchis (Digenea: Cyathocotylidae) is a parasite of birds, transmitted by freshwater fishes. H. metorchis adults were recovered from chicks experimentally infected with metacercariae collected from freshwater fishes, Pseudorasbora parva. The metacercariae were oval, surrounded with thick fibrous capsules. In adult flukes, the holdfast organ occupied the ventral concavity, and the anterior testis did not reach the level of the ventral sucker. Based on these morphological characteristics, these flukes were identified as H. metorchis. [ABSTRACT FROM AUTHOR]

Abstract   Cyclops leuckarti and C. prasinus can serve as the intermediate hosts of Ophiotaenia monnigi, Fuhrmann, 1924. From the hexacanth, the parasite developed to a mature procercoid larva without a cercomere, although it appeared in the development processes. At the two-part development stage, all the hooks transferred to the cercomere, and it dropped off in the latest time of the larval developing. In the development, a coelom presented in the front part as well as in the cercomere. An apical appeared, and two pairs of gland cells were found after the sucker. The whole developmental course took more than 11 days, and it was even longer in the host, C. prasinus, in which the parasite larva developed slower. [ABSTRACT FROM AUTHOR]

Abstract: Quaking aspen (Populus tremuloides) is commonly believed to be declining throughout western North America. A literature review of recent local-scale aspen studies, however, indicates that regional-scale spatial variability in aspen dynamics is greater than previously recognized and there are areas of successful aspen regeneration and recruitment. This study examines 20th century aspen recruitment and regeneration patterns along a 15km long lower forest–grassland ecotone in the Centennial Valley, Montana to determine if the Centennial Valley ecotone aspen stands support the observation that there are areas of successful recruitment and regeneration and provide another example of such areas. A total of 525 adult aspen stems were cored and 8924 aspen suckers were counted and mapped in 106 rectangular plots randomly distributed along the ecotone. Aspen-age distribution was constructed at a decadal time scale to examine 20th century recruitment patterns. Sucker density was examined to evaluate aspen regeneration. The tree-age distribution patterns indicated successful aspen recruitment during the 20th century, while the sucker density assessment suggested successful regeneration. The Centennial Valley ecotone aspen stands appear to support the observation that aspen recruitment and regeneration are spatially variable and there are areas of aspen persistence. Learning about the underlying factors that enable successful aspen regeneration and recruitment in such areas can help management and restoration activities at other locales. Recognizing the regional-scale spatial variability in aspen dynamics can inform regional-level policy and management. [Copyright &y& Elsevier]

Otolith thermal marking was conducted in larval Chinese sucker, Myxocyprinus asiaticus, by exposing the larvae to water with different temperature regimes ranging from heated water (28°C) to chilled water (16°C) at different time intervals. The results showed that increment patterns differed among groups; the control of duration in the heated water could produce some increments much narrower or wider than those deposited in the natural diel water temperature fluctuation; there was a significantly positive relation between increment width and the duration reared in heated water in each cycle of water temperature fluctuation. These increments with abnormal widths were thermal marks in otoliths, and would be used as bar codes to track the released individuals, and discriminate them from the wild populations in the future. The thermal marking is suitable to mass-mark the Chinese sucker larvae. [ABSTRACT FROM AUTHOR]

Abstract: This study assessed the recovery of the structure and species composition of a laurel forest in an abandoned firebreak in the Rural Park of Anaga, Tenerife (Canary Islands). We statistically compared values of species richness, density and biovolume between 23 plots in the firebreak and six control plots in natural forest near the firebreak. We evaluated changes in species composition with detrended correspondence analysis (DCA) based on densities and biovolume. Biovolume is increasing significantly along the successional gradient (from 1990 to 2004) but remains less than the values in control plots. Stem densities were significantly lower in control plots than in 2004 plots. Species richness was significantly higher in control plots than in 2004 plots (although there were no differences in values obtained between the first sampling period 6years after abandonment, and the second sampling 20years after abandonment). Changes in species richness are significant, but all species present in control plots are also found in the firebreak plots. DCA based on biovolume significantly discriminated control plots from firebreak plots in 1990 (for axis I). Results suggest recovery to a laurel forest is occurring, although more time will be required to reach control plot density and biovolume values. The low intensity of disturbance and a well-conserved forest adjacent to the firebreak favour the recovery of species inside the firebreak. We advise eliminating suckers from all small trees (leaving the bigger stems) to accelerate succession to a vegetation structure similar to that found surrounding the firebreak. [Copyright &y& Elsevier]

Trembling aspen (Populus tremuloides Michx.) is capable of regenerating vegetatively through the formation of adventitious shoots (suckers) from roots. This field study investigated how sucker regeneration following harvest of aspen is affected by understories of beaked hazel (Corylus cornuta Marsh.). Aspen stands with a high density of understory hazel (>45 000 stems per hectare (sph)) or a low density (<5000 sph) were cut in the fall. After one growing season, aspen sucker density and growth were assessed. Soil trenches were excavated to examine the root density and rooting depth of both aspen and hazel. Aspen sucker regeneration was 68 200 sph in areas with low hazel density and 43 600 sph in areas with high hazel density; the cross-sectional surface area of aspen roots in shallow soil layers (0–10 cm) was significantly lower under high densities of hazel. As aspen usually produces most of its root suckers from shallow roots, the reduction of roots in the upper 10 cm of the soil was the likely cause of lower sucker densities. Height growth of the suckers was not influenced by pre-harvest hazel density, possibly owing to high light transmission as a result of the reduced leaf area of the hazel after the harvest. [ABSTRACT FROM AUTHOR]

Marsh reed grass (Calamagrostis canadensis (Michx.) Beauv.) is a common, highly competitive grass native to the boreal mixedwood forest. This grass increases in abundance after clear-cut logging but little is known about its effects on trembling aspen (Populus tremuloides Michx.) sucker regeneration. The effects of Calamagrostis sod and its litter on aspen regeneration were studied in two separate greenhouse studies. Calamagrostis sod did not affect the initiation of suckers, but resulted in 30 per cent fewer suckers emerging above the soil that were smaller and had 40 per cent less leaf area. Calamagrostis litter had little effect on the initiation and number of emerged suckers; however, it delayed emergence by 10 days. The physical barrier by roots and litter of Calamagrostis reduced or delayed the expansion of suckers and therefore prolonged their dependence on root reserves. By the time the suckers reached the surface, they had to compete for light with Calamagrostis shoots that had emerged a week earlier. This, coupled with low soil temperatures associated with Calamagrostis in other experiments, will significantly reduce the number and growth of suckers. Any reduction and delay in sucker emergence will decrease aspen regeneration and productivity since the growing season in the boreal forest region is short. [ABSTRACT FROM AUTHOR]

Potential effects of body size changes on locomotor performance in gobiid fishes (family Gobiidae) were studied in two sicydiine species, Sicyopterus stimpsoni from the Hawaiian Islands and Sicydium punctatum from Dominica, West Indies. These taxa both possess a pelvic sucking disc that can be used to adhere to rock surfaces during bouts of waterfall climbing. If this disc scaled isometrically as body size increased, climbing might be impaired in larger fish because body mass increases faster during growth than the area of the sucker that supports body weight. To test whether the pelvic sucker grows in a way that could help maintain climbing performance in large gobies (and that is distinctive compared to other fins), we evaluated the scaling of sucker area, caudal-fin height, and pectoral-Fm length with respect to total body length in Sicyopterus and Sicydium across a range of body sizes. Sucker area scaled isometrically with body length for both species, suggesting that climbing performance might decline as these fishes grow. Although the pectoral fin scaled differently in the two species, caudal-fin height showed strong positive allometry relative to body length in both species. The differing scaling patterns of sucker area and caudal-fin height relative to body length may reflect an increase in the importance of swimming over climbing in sicydiine gobies as they grow larger. Moreover, similarities in the scaling patterns of gobies from geographically distant islands suggest that species in this lineage may be subject to common ontogenetic constraints on performance. [ABSTRACT FROM AUTHOR]

Blue sucker, Cycleptus elongatus (Le Sueur), was sampled in the Kansas River, Kansas, USA to determine how relative abundance varies spatially and growth compares to other populations. Electric fishing was conducted at 36 fixed sites during five time periods from March 2005 to January 2006 to determine seasonal distribution. An additional 302 sites were sampled in summer 2005 to determine distribution throughout the river. A total of 101 blue sucker was collected ranging from 242 to 782 mm total length and 1–16 years old. Higher catch rates were observed in upper river segments and below a low-head dam in lower river segments, and catch rates were higher during November in the upriver sites. Kansas River blue sucker exhibited slower growth rates than other populations in the Great Plains including populations as far north as South Dakota. [ABSTRACT FROM AUTHOR]

An important issue surrounding biomonitoring in large rivers is the minimum sampling effort required to collect an adequate number of fish for accurate and precise determinations of biotic condition. During the summer of 2002, we sampled 15 randomly selected large-river sites in southern Idaho to evaluate the effects of sampling effort on an index of biotic integrity (IBI). Boat electrofishing was used to collect sample populations of fish in river reaches representing 40 and 100 times the mean channel width (MCW; wetted channel) at base flow. Minimum sampling effort was assessed by comparing the relation between reach length sampled and change in IBI score. Thirty-two species of fish in the families Catostomidae, Centrarchidae, Cottidae, Cyprinidae, Ictaluridae, Percidae, and Salmonidae were collected. Of these, 12 alien species were collected at 80% (12 of 15) of the sample sites; alien species represented about 38% of all species (N = 32) collected during the study. A total of 60% (9 of 15) of the sample sites had poor IBI scores. A minimum reach length of about 36 times MCW was determined to be sufficient for collecting an adequate number of fish for estimating biotic condition based on an IBI score. For most sites, this equates to collecting 275 fish at a site. Results may be applicable to other semiarid, fifth-order through seventh-order rivers sampled during summer low-flow conditions. [ABSTRACT FROM AUTHOR]

Fisheries assessment tools originally created for use with game fish populations are now helping to assess individual nongame species and to evaluate fish communities. Length and weight measurements of individuals within a species can be summarized into condition indices that give insight into the health and condition of the individual and the aquatic community. Such data (weight [g] and total length [TL, mm]) were obtained for 105 populations of bridgelip suckers Catostomus columbianus and 135 populations of largescale suckers C. macrocheilus from three northwestern states. These data were used to develop standard weight (Ws) equations via the regression-line percentile (RLP) and empirical percentile (EmP) methods. Length constraints were 130-460 mm TL for bridgelip suckers and 1704540 mm TL for largescale suckers. The data set was limited by TL constraints and split into development and validation sets. The RLP method yielded the following W equations: log10W s = -5.01699 + 3.02648·log10TL for bridgelip suckers and log10Ws = -4.94684 + 2.99720-log10TL for largescale suckers. Equations based on the EmP method were log10Ws = -5.09721 + 3.04947·log10TL for bridgelip suckers and log10Ws = -5.2586 + 3.12136·log10TL for largescale suckers. For both species, the relative weights produced from RLP and EmP equations differed by less than 10%. However, differences were inconsistent over the length range, indicating a length-related bias. Based on this assessment, use of EmP Ws equations for bridgelip suckers and largescale suckers is recommended. Further, the EmP method should be used to establish new Ws equations. [ABSTRACT FROM AUTHOR]