John Lyons

Capture Efficiency of a Beach Seine for Seven Freshwater Fishes in a North-Temperate Lake

Abstract Daytime seining efficiencies were estimated for shoreline fish populations in Sparkling Lake, a small mesotrophic clear-water lake in northern Wisconsin. Except for rock bass (Ambloplites rupestris), efficiency was related to the typical position of each species in the water column; efficiencies were higher for midwater fishes (cyprinids and yellow perch, Perca flavescens) than for benthic fishes (darters, Etheostoma spp.). Efficiencies for many species might be improved by modifications of seining technique or use of heavier lead lines that would keep the seine closer to the bottom.

Effects of Walleye Predation on the Population Dynamics of Small Littoral-Zone Fishes in a Northern Wisconsin Lake

Abstract We used a bioenergetics model to assess the effects of predation by juvenile walleyes Stizostedion vitreum vitreum on the populations of darters (Percidae) and minnows (Cyprinidae) in Sparkling Lake, Wisconsin. In 1982, when young-of-the-year yellow perch Perca flavescens were scarce, darters and minnows were important in walleye diets throughout the summer. Walleye predation accounted for approximately 100% of adult darter mortality and 75% of adult minnow mortality. Walleyes appeared to be important in determining abundance of young-of-the-year darters in October, but had little direct effect on abundance of young-of-the-year minnows. In 1983, when young-of-the-year yellow perch were abundant, darters and minnows were only important in walleye diets in June. Walleye predation accounted for 80% of adult darter mortality but only 35% of adult minnow mortality. The decrease in walleye consumption of adult darters and minnows in 1983 compared with 1982 is consistent with the hypothesis that abundan...

Dynamics of upstream migration in two species of tropical freshwater snails

Much of the fauna of the Río Claro on the Osa Peninsula of Costa Rica, including snails, fishes, and freshwater shrimp, migrates upstream, sometimes in large aggregations. We investigated the dynamics of the migratory behavior of the snails Neritina latissima and Cochliopina tryoniana, which both migrate upstream in huge, mixed aggregations (>500,000 individuals) during the dry season. Yet these two species have very different life histories. Neritina latissima has pelagic larvae which are swept downstream to the ocean. Metamorphosed individuals migrate upstream. Cochliopina tryoniana has direct development, with no marine stage. We analyzed the size distribution of the migrating, stationary, and drifting portions of the populations of these two species. In the drift, we collected only larval N. latissima. Analysis of the size distribution of the migrating and stationary snails suggested that the migration takes >1 yr for N. latissima and perhaps <1 yr for C. tryoniana. In both species, the migration behavior was size and age dependent. Juveniles and small adults composed the bulk of the migrating populations, whereas large adults were almost never observed to migrate. The mean size of individuals in migrating aggregations increased over time and distance upstream. Sphoeroides annulatus, a marine molluscivorous fish, was found only in the lower reaches of the stream. Where S. annulatus was common, N. latissima was less abundant and located on the underside of rocks. The distance migrated may be a balance between size-dependent energetic constraints on upstream movement and increased predation pressure downstream.

Factors influencing fish distribution and community structure in a small coastal river in southwestern Costa Rica

We evaluated the relative importance of habitat size and diversity and distance from the ocean in explaining longitudinal patterns of fish distribution and community structure (species richness, evenness, and diversity) in the lower 5 km of the Rio Claro. The Rio Claro is a small coastal river in Corcovado National Park, southwestern Costa Rica, with a depauperate freshwater fish fauna. We observed 22 species in pools, 19 of which occured during quantitative sampling. Most of these species probably spent part of their lives in the Pacific Ocean. We observed no species in riffles, although these habitats were common and several taxa (e.g., Gobiesocidae, Gobiidae) were adapted for life in fast turbulent water. Fish abundance, and species richness, evenness, and diversity were highest near the ocean, where high tides influenced river levels and salinity. Eight species were not observed further than 2900 m from the ocean, whereas 6 species were not encountered in samples nearest the ocean; the remaining 8 species were present throughout the study area. Distance from the ocean was a better predictor of fish abundance and community structure than were pool width, pool depth, pool surface area, pool volume, amount of cover present, substrate diversity, or depth diversity. Based in qualitative comparisons of our data with previously published data from 1980–1986, the fish assemblage of the Rio Claro is persistent in both species composition and relative abundance.

Systematics and Biogeography of the Silverside Tribe Menidiini (Teleostomi: Atherinopsidae) Based on the Mitochondrial ND2 Gene

Abstract The silverside fish tribe Menidiini (Teleostei: Atherinopsidae) consists of four genera, Menidia, Labidesthes, Poblana, and Chirostoma, that are distributed along the Atlantic coast of North America, throughout the Gulf of México, insular United States, and the Mesa Central of México. It has been suggested that Chirostoma, Poblana, and Menidia should be recognized as a single genus under the nominal Menidia. To test this hypothesis, phylogenetic relationships within the tribe Menidiini were assessed using the mitochondrially encoded ND2 gene. Monophyly of the Menidiini tribe was supported. Results also failed to support monophyly for the genera Menidia and Chirostoma as currently recognized. A central Mexican clade, inclusive of Chirostoma and Poblana, was recovered as monophyletic and strongly supported. Relationships within the Mesa Central clade support a previously recognized “humboldtianum” clade and the paraphyly of Chirostoma with respect to Poblana.

Distribution, abundance, and mortality of small littoral-zone fishes in Sparkling Lake, Wisconsin

SynopsisDuring 1982 and 1983, seining, fyke netting, and SCUBA observation were used to determine the depth distribution, abundance, and mortality of small littoral-zone fishes (bluntnose minnows, shiners [primarily mimic shiners], yellow perch, logperch, johnny darters, Iowa darters, and mottled sculpins) in Sparkling Lake, a small moderately-productive lake in northern Wisconsin. During the summer cyprinids, darters, and mottled sculpins were most abundant in areas shallower than 1 m, while yellow perch were most abundant at depths of 2 to 4 m. Between August and October cyprinids and yellow perch moved to water 1 to 2 m deeper, while the depth distributions of darters and mottled sculpins generally remained unchanged. Large within- and between-year variations in abundances and mortality rates were evident for all species. In 1982, most of the mortality of cyprinids and darters occurred during a short period in late spring and early summer, with relatively little afterwards. In 1983, this pattern was reversed for cyprinids and Iowa darters, but not logperch and johnny darters. Between-year differences in abundance were greatest for young-of-the-year yellow perch; they were 400 times more numerous in 1983 than in 1982. Darters had their lowest mortality rates and highest reproductive success in 1983, while the opposite was true for cyprinids. This lack of synchrony between darters and cyprinids suggests that these two taxa responded differently to changes in environmental conditions in Sparkling Lake. Predation may have accounted for much of the variability in darter population parameters, but appeared to be a less important source of variation for cyprinid population parameters.

Effects of lethal acidity on plasma sodium concentrations in yellow perch (Perca flavescens) from a naturally acidic and a naturally alkaline lake

Abstract 1. 1. In situ plasma sodium concentrations of yellow perch ( Perca fluvescens ) from naturally acidic Wharton lake (pH 4.6) and naturally alkaline Trout lake (pH 7.9) were similar. 2. 2. Exposure to lethal acidity (pH 3.2) for 48 hr resulted in significant but similar decreases in plasma sodium levels in both populations, even though Whartor lake perch were known to survive significantly longer than Trout lake perch at low pH. 3. 3. This suggests that the observed differences in acidity tolerance between the two populations are not due to differences in rates of plasma sodium decrease.

Fish and Macroinvertebrates as Freshwater Ecosystem Bioindicators in Mexico: Current State and Perspectives

In Mexico 78 per cent of water is used for agriculture, 12 per cent for household use and 10 per cent for industry. Once water is used in agricultural settings, wastewater containing agrochemicals and other chemicals is generated and released to rivers. In addition, 14 km3/year1 is generated from industry (43.8 per cent) and from water use in municipalities (56.2 per cent), which is also released into rivers and lakes throughout the country (CONAGUA, 2008).

Temporal and spatial patterns of spawning site use by two cavity-spawning darters in a Wisconsin stream

SynopsisThere was partial spatial and complete temporal overlap of spawning by Etheostoma flabellare and E. nigrum in Marsh Creek, Wisconsin. E. flabellare tended to spawn at shallower depths than E. nigrum. Both species spawned over a greater range of depths in an area with few spawning sites (cavities under rocks or logs) than in an area where spawning sites were abundant. In the laboratory E. flabellare were able to prevent E. nigrum from occupying cavities they would have otherwise occupied. E. nigrum appear to be competitively inferior to E. flabellare in terms of spawning-site acquisition and retention, but possess several attributes that may allow them to persist in the presence of the latter.

Threatened fishes of the world: Allotoca goslinei Smith and Miller, 1987 (Goodeidae)

Common Names: banded allotoca, tiro rayado (Sp.). Conservation status: Endangered (Williams et al. 1989). Identification: ML 50 mm, distinguished from congeners by 15 narrow vertical bars (Smith and Miller 1987). Illustration by S. Fink. Distribution: Two localities on Arroyo Potrero Grande, Ameca tributary, Jalisco, Mexico. Abundance: Likely extinct in nature: In 2000, A. goslinei was the dominant fish at the type locality (ca. 75% proportional abundance). We extensively sampled the tributary in 2005–2006 and found none. Habitat and ecology: Associated with plants in shallow pools; likely feeds on small arthropods based on the diet of its sister species (Dominguez-Dominguez et al. 2002; Doadrio and Dominguez-Dominguez 2004; Webb et al. 2004). Cohabitates with natives: Allodontichthys polylepis, Poeciliopsis infans, Scartomyzon austrinus, Ilyodon furcidens (Wischnath 1993). Reproduction: Livebearer; sexual dimorphism in fin placement and coloration (Smith and Miller 1987). In captivity, sexual maturity reached within 3 months; broods of Environ Biol Fish (2009) 84:197–198 DOI 10.1007/s10641-008-9406-y