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D.M. Gadomski

Publications and source records attributed to D.M. Gadomski.

18 recordsLinked to original sources
USGS2011

Effects of turbidity, light level, and cover on predation of white sturgeon larvae by prickly sculpins

White sturgeon Acipenser transmontanus occur in rivers of the western United States and southwestern Canada, but some populations are in decline because of recruitment failure. Many river systems in this area have been altered as a result of development that has caused major environmental changes. Our goal was to examine how three changes - lower turbidity levels, higher light levels, and altered substrates - might affect predation by prickly sculpin Cottus asper on white sturgeon larvae. We experimentally investigated predation at various turbidity levels and found that significantly more white sturgeon yolk sac larvae were eaten at lower turbidity levels. The effects of light level (1-4 and 7-15 1x), the presence or absence of rocks as cover, and prey size (14-17 mm and 20-24 mm total length) on the outcome of predator-prey interactions were also examined. Significantly fewer white sturgeon were eaten during trials that combined the lowest light level, cover, and the smallest larvae. Our results suggest that altered river conditions caused by impoundment and other factors have increased predation on white sturgeon larvae. ?? Copyright by the American Fisheries Society 2005.

Transactions of the American Fisheries Society↗
USGS2005

Laboratory studies on the vulnerability of young white sturgeon to predation

Despite evidence of annual spawning by white sturgeon Acipenser transmontanus in rivers of the northwestern United States and Canada, in some years and locations little or no recruitment of age-0 white sturgeon has been observed. We examined the vulnerability of white sturgeon larvae and juveniles to predation to further understand possible causes of mortality. We were particularly interested in the vulnerability of older larvae and juveniles because at about 25 mm total length (TL) white sturgeon develop sharp dorsal and lateral scutes that may act as a morphological defense. In the laboratory, white sturgeon ranging from newly hatched larvae to about 170-mm TL juveniles were exposed to predatory fishes they might encounter in the natural environment. We found that channel catfish Ictalurus punctatus (mean TL = 464 mm) and northern pikeminnow Ptychocheilus oregonensis (mean TL = 472 mm) ate white sturgeon up to mean sizes of 121 and 134 mm TL, respectively. Conversely, similarly sized walleyes Sander vitreus ingested almost no white sturgeon, although juvenile walleyes (mean TL = 184 mm) ate white sturgeon up to 59 mm TL. The smallest predator we tested, prickly sculpins Cottus asper (mean TL = 126 mm), ate white sturgeon up to a mean TL of 50 mm. Our study demonstrated that predation is a likely cause of mortality of age-0 white sturgeon and may be contributing to the year-class failures that have been observed. In addition, the results from this study could be used to reduce the predation risk of artificially propagated white sturgeon released to augment declining populations since fish could be reared to sizes where their vulnerability is low.

North American Journal of Fisheries Management↗
USGS2004

Persistence of identifiable remains of white sturgeon juveniles in digestive tracts of northern pikeminnow

Juvenile white sturgeon, Acipenser transmontanus, have not been commonly identified as prey items in digestive tracts of fishes collected in the wild. In particular, the diet of northern pikeminnow, Ptychocheilus oregonensis, an abundant Pacific Northwest freshwater predator which has been widely studied, has not included juvenile white sturgeon. To aid in interpreting these results and help in planning future feeding studies, we determined the persistence of identifiable remains of white sturgeon juveniles in this predator's digestive tract. Northern pikeminnow (mean total length = 476 mm), were force-fed meals of 2 or 3 juvenile white sturgeon (mean total length = 91 mm). After digestive periods of 4, 8, 16, 24, 28, and 32h at a water temperature of about 17 ??C, fish were sacrificed, digestive tracts removed, and contents examined. Our results indicate that juvenile white sturgeon would be readily discernable in digestive tracts of northern pikeminnow at least a day after feeding, with scutes remaining undigested and identifiable for 28 h.

California Fish and Game↗
USGS2003

American shad in the Columbia River

American shad Alosa sapidissima from the Hudson River, New York, were introduced into the Sacramento River, California, in 1871 and were first observed in the Columbia River in 1876. American shad returns to the Columbia River increased greatly between 1960 and 1990, and recently 2-4 million adults have been counted per year at Bonneville Dam, Oregon and Washington State (river kilometer 235). The total return of American shad is likely much higher than this dam count. Returning adults migrate as far as 600 km up the Columbia and Snake rivers, passing as many as eight large hydroelectric dams. Spawning occurs primarily in the lower river and in several large reservoirs. A small sample found returning adults were 2-6 years old and about one-third of adults were repeat spawners. Larval American shad are abundant in plankton and in the nearshore zone. Juvenile American shad occur throughout the water column during night, but school near the bottom or inshore during day. Juveniles consume a variety of zooplankton, but cyclopoid copepods were 86% of the diet by mass. Juveniles emigrate from the river from August through December. Annual exploitation of American shad by commercial and recreational fisheries combined is near 9% of the total count at Bonneville Dam. The success of American shad in the Columbia River is likely related to successful passage at dams, good spawning and rearing habitats, and low exploitation. The role of American shad within the aquatic community is poorly understood. We speculate that juveniles could alter the zooplankton community and may supplement the diet of resident predators. Data, however, are lacking or sparse in some areas, and more information is needed on the role of larval and juvenile American shad in the food web, factors limiting adult returns, ocean distribution of adults, and interactions between American shad and endangered or threatened salmonids throughout the river. ?? 2003 by the American Fisheries Society.

Book chapter↗
USGS2002

Resident fish assemblages in shallow shorelines of a Columbia River impoundment

During May-September 1995, we replicated an earlier (1984-85) study of fishes in shoreline habitats of the John Day Reservoir, Columbia River, to investigate fish assemblage structure at several spatial and temporal scales. A total of 37,400 resident fishes representing 24 taxa was collected in 359 beach seine hauls. Fish catch composition during 1984 and 1985 was very similar, but was greatly different from catch in 1995. During 1984-1985, four native taxa (chiselmouth, northern pikeminnow, suckers, and sand rollers) constituted more than 90% of the combined main-channel catch, with introduced taxa comprising only 1.3% of the main-channel catch. In contrast, during 1995 only 37.7% of the main-channel catch comprised chiselmouth, northern pikeminnow, suckers, and sand rollers, while 33.9% were introduced taxa, primarily sunfishes and yellow perch. This shift in catch composition was greatest in the lower reservoir where the 1995 catch was 61% introduced taxa. Although changes in species composition of near-shore reservoir fish assemblages over the 10-yr period appeared to be substantial, we are unsure of annual variability since we have only one season of sampling for comparison with the earlier study. The differences we observed could be a long-term response to reservoir aging, a short-term reaction to annual differences in hydrologic and thermal regimes, or simply the naturally varying reproductive success of some species.

Northwest Science↗
USGS2001

Early life history of the northern pikeminnow in the lower Columbia River basin

The northern pikeminnow Ptychocheilus oregonensis is a large, native cyprinid in the Columbia River basin that has persisted in spite of substantial habitat alterations. During the months of June to September 1993-1996, we investigated the temporal and spatial patterns of northern pikeminnow spawning, along with describing larval drift and characterizing larval and early juvenile rearing habitats in the lower Columbia River (the John Day and Dalles reservoirs and the free-flowing section downstream of Bonneville Dam) as well as in the lower sections of two major tributaries (the John Day and Deschutes rivers). The density of newly emerged drifting larvae was higher in dam tailraces (a mean of 7.7 larvae/100 m3 in surface tows) than in the lower reservoirs (0.3 larvae/100 m3), indicating that tailraces were areas of more intense spawning. Density was particularly high in the Bonneville Dam tailrace (15.1 larvae/100 m3), perhaps because adult northern pikeminnow are abundant below Bonneville Dam and this is the first tailrace and suitable main-stem spawning habitat encountered during upriver spawning migrations. Spawning also occurred in both of the tributaries sampled but not in a backwater. Spawning in the Columbia River primarily took place during the month of June in 1993 and 1994, when the water temperature rose from 14??C to 18??C, but occurred about 2 weeks later in 1995 and 1996, possibly because of cooler June water temperature (14-15??C) in these years. The period of drift was brief (about 1-3 d), with larvae recruiting to shallow, low-velocity shorelines of main-channel and backwater areas to rear. Larvae reared in greatest densities at sites with fine sediment or sand substrates and moderate- to high-density vegetation (a mean density of 92.1 larvae/10 m3). The success of northern pikeminnow in the Columbia River basin may be partly attributable to their ability to locate adequate spawning and rearing conditions in a variety of main-stem and tributary locations.

Oregon; Washington↗
USGS1999

Growth and mortality of age-0 northern squawfish, Ptychocheilus oregonensis , rearing in shoreline habitats of the Columbia River Reservoir

We investigated growth and mortality of age-0 northern squawfish during early rearing in shallow shoreline habitats. Larvae and juveniles (n=22914) were collected by weekly seining at three sample sites in the upper John Day Reservoir, Columbia River, during June through early September 1994–1996. Using a length-based ageing method, it was estimated that the exponential growth rate (G) for a common growth stanza (10–28 mm standard length SL) was significantly higher in 1994 (G=0.047) than in 1996 (G=0.037). Growth rate in 1995 could not be estimated, but was probably intermediate between 1994 and 1996 based on mean standard lengths of fish collected at the end of each sampling season (46.3, 40.0, and 32.0 mm SL in 1994, 1995, and 1996, respectively). For many fish species, variations in early growth can influence survival through size-selective mortality processes. Consistent with this possibility, our estimates of instantaneous mortality rates (Z) demonstrated that larvae and juveniles had significantly higher mortality in 1996 than in 1994 (Z=0.103 in 1994, versus Z=0.138 in 1996). Enhanced growth and lower mortality in 1994 were associated with a number of interrelated environmental conditions – comparatively low flows and turbidities, abundant instream vegetative cover, and high near-shore water temperatures.

Oregon↗
USGS1998

Diel and distributional abundance patterns of fish embryos and larvae in the lower Columbia and Deschutes rivers

Diel and distributional abundance patterns of free embryos and larvae of fishes in the lower Columbia River Basin were investigated. Ichthyoplankton samples were collected in 1993 during day and night in the main-channel and a backwater of the lower Columbia River, and in a tributary, the Deschutes River. Fish embryos and larvae collected in the main-channel Columbia River were primarily (85.6%) of native taxa (peamouth Mylocheilus caurinus, northern squawfish Ptychocheilus oregonensis, suckers Catostomus spp., and sculpins Cottus spp.), with two introduced species (American shad Alosa sapidissima and common carp Cyprinus carpio) comprising a smaller percentage of the catch (13.3%). Similarly, in the Deschutes River native taxa [lampreys (Petromyzontidae), minnows (Cyprinidae), and suckers Catostomus spp.] dominated collections (99.5% of the catch). In contrast, 83.5% of embryos and larvae in the Columbia River backwater were of introduced taxa [American shad, common carp, and sunfishes (Centrarchidae)]. In all locations, all dominant taxa except sculpins were collected in significantly greater proportions at night. Taxon-specific differences in proportions of embryos and larvae collected at night can in some instances be related to life history styles. In the main-channel Columbia River, northern squawfish and peamouth were strongly nocturnal and high proportions still had yolksacs, suggesting that they had recently hatched and were drifting downriver to rearing areas. In contrast, sculpin abundances were similar during day and night, and sculpins mostly had depleted yolksacs, indicating sculpins were feeding and rearing in offshore limnetic habitats. Taxon-specific diel abundance patterns and their causes must be considered when designing effective sampling programs for fish embryos and larvae.

Oregon↗
USGS1996

Effects of temperature on the development and survival of eggs of four coastal California fishes

Laboratory experiments were conducted to determine the effects of temperature on egg development and survival of four fish species found off southern California. Our objectives were to further understanding ofnatural spawning patterns and to aid in identifying and ageing field-collected specimens. An egg-staging procedure was devised and eggs were observed every two hours during development at a range of temperatures (8-28°Cl. Barred sand bass, Parolabrax nebulifer, eggs survived to hatching and produced viable embryos at the highest temperature range (l6-28°C), reflecting this species'summerspawning season. Fantail sole, Xystreurys liolepis, eggs also hatched at a higher temperature range (l6-24°C). This species spawns primarily from summer through fall. Eggs of the two species with winter-spring spawning peaks, white croaker, Genyonemuslineatus, and California halibut, Paralichthys californicus, had lower temperature-tolerance ranges (12- 2O"C). Developmental rate at a specific temperature did not significantly differ between species, whereas within tolerance limits, temperature strongly affected rate of development for all species. Time to hatching for all species was inversely related to temperature, and the relationship was approximately exponential. Species-specific differences in egg-stage sequence were observed; embryonic organogenesisin relation to germ-ring migration and blastopore closure was faster for barred sand bass and fantail sole than for white croaker and California halibut.

Fishery Bulletin↗
USGS1991

Effects of temperature on early-life-history stages of California halibut Paralichthys californicus

- Laboratory experiments were conducted to determine how growth and survival of earlylife-history stages of California halibut Pamlichthys californicus are influenced by temperature, and how optimal temperature ranges may change with ontogeny. As halibut developed from eggs to juveniles, highest survival occurred at increasingly higher temperature ranges. Within tolerance limits, growth and development rates of all early-lifehistory stages were directly proportional to temperature. Eggs hatched successfully at 12, 16, and 20°C; at g and 24°C they died prior to embryo formation. Larval survival 17 days after hatching was 23-46% at 16, 20, and 24°C, but almost all larvae died at 12°C after an initial period of high survival. At gOC,larvai development ceased at the early yolksac stage. Survival of 3-month-old juvenile halibut was significantly greater at 20, 24. and 28°C (57-76°70) than at 16°C (31%). Temperature also affected settlement rate; when the temperature of I-month-old larvae was raised from 16°C to 20°C, settlement occurred about a week sooner than settlement of larvae remaining at 16°C. Tolerance ranges of halibut earlylife-history stages determined in the laboratory approximate temperatures encountered by halibut in the field; high densities of newly-settled halibut larvae and juveniles have been collected in shallow areas of bays where temperatures are often higher than the open ocean inhabited by young larvae. These warmer inshore nursery grounds could enhance growth and survival of halibut juveniles.

Fishery Bulletin↗
USGS1988

Effects of food deprivation on the larvae of two flatfishes

For greatest survival, first-feeding halibut Paralichthys californicus and diamond turbot Hypsopsetta guttulata required food by the day of total yolk absorption. Some halibut larvae survived if fed 1 or 2 d after yolk depletion, but their growth rate was significantly less than larvae fed earlier. Survival of 3-wk-old larvae was greater in treatments with shorter starvation periods. A small percentage of 3-wk-old halibut larvae recovered from a maximum starvation period of 4 d while 3-wk-old diamond turbot successfully resumed feeding any time during food deprivation intervals lasting up to 9 d. Longer periods of starvation resulted in significant morphological differences – diamond turbot starved longer were not only smaller, but also less developed. In the field, larvae may experience varying periods of food deprivation due to differing spatial and temporal prey patch distributions. Our results demonstrate that differences in starvation resistance, and possibly mortality under patchy feeding conditions, are ontogenetic and species-specific.

Marine Ecology Progress Series↗