[show abstract][hide abstract] ABSTRACT: We compared the impact of exposure to seawater on three sockeye salmon (Oncorhynchus nerka) stocks: one that normally migrates to sea as underyearlings (sea-type) and two with the more common life history strategies of 1 (river-type) or 2 (lake-type) yr of freshwater residence prior to seaward migration. Innate differences in survival, ability to regulate tissue chlorides, and oxygen consumption when first introduced into salt water were more evident in April and May when fish were less than 50 mm in length. In fish longer than 50 mm, the only significant differences among the stocks were in saltwater growth. Between June and August, sea-type fish showed faster growth than river-type fish which in turn grew faster than lake-type fish. When introduced into salt water in October, virtually no growth occurred in any stock, regardless of fish size. River-type and lake-type sockeye, which normally overwinter 1 and 2 yr, respectively, in freshwater, can be reared in seawater if underyearlings are raised to a length of 50 mm before release into salt water, similar to the normal life history of sea-type underyearlings. Early life history appears to be influenced more by habitat than by genetics.
Canadian Journal of Fisheries and Aquatic Sciences 04/2011; 51(4):974-980. · 2.32 Impact Factor
[show abstract][hide abstract] ABSTRACT: Coho salmon (Oncorhynchus kisutch) smolts infected with the nematode Philonema agubernaculum had 36% lower mean lipid content (1.4%) than nonparasitized coho salmon (2.2%) harvested simultaneously from the same outmigration. Lengths, weights, and condition factors, as well as protein and moisture content, did not differ significantly between the two groups. Lipid class compositions differed significantly between the parasitized and nonparasitized fish. None of the nematode-infected fish contained detectable triacylglycerols (TAG) or monoacylglycerols (MAG). In contrast, mean TAG and MAG contents of the nonparasitized fish totaled 5.5% of the extracted lipid. Infected smolts had lower cholesterol contents than did uninfected coho (17% for infected, 33% for uninfected). Parasitized fish had significantly higher levels of free fatty acids (mean of 57% for parasitized vs. 35% for nonparasitized) as well as the phospholipids phosphatidylethanolamine (PE) and phosphatidylcholine (PC). However, the PC/PE ratios for infected and noninfected coho did not differ significantly (2.2 for infected vs. 2.0 for uninfected). These differences suggest that the parasitic nematodes are either harvesting storage energy directly from the coho or are placing additional energetic demands on the fish to cope with the infection.
Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology 02/2008; 149(1):148-52. · 2.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine if hydrocarbon levels in salmon-rearing lakes are affected by seasonal increases in the number of two-stroke powered watercraft, passive hydrocarbon sampling devices were deployed in Auke Lake in southeast Alaska for five successive summers (1999–2003). Estimates of the number of two-stroke powered water craft were made by daily census in 2003. Passive samplers mimic the bioconcentration of trace waterborne lipophilic contaminants by living organisms and are used worldwide for in situ monitoring of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Monthly increases in PAHs coincided with monthly increases in the number of two-stroke powered watercraft (jet skis and powerboats) on the lake during the summer. This increase in PAHs varied in magnitude from year to year. PAHs were detected in the surface waters (1 m), particularly in high use areas, and were not detected at 9 m depth. These localized seasonal inputs appeared to come primarily from recreational watercraft rather than from runoff. Alaska's recreational boating season is very compressed and coincides with migrations of anadromous fish. Increased use of two-stroke engines may transfer enough hydrocarbons to the lake to affect fish populations.
Lake and Reservoir Management - LAKE RESERV MANAG. 01/2008; 24(1):10-17.
[show abstract][hide abstract] ABSTRACT: Conventional passive sampling devices for monitoring pollution input often prove to be cost-prohibitive when assessing large spatial and temporal scales. The Kenai River, a major salmon-producing river in Alaska (USA), served as the perfect laboratory to test the utility of polyethylene membrane devices for assessing chronic nonpoint-source inputs to a large riverine watershed. Comparison of the relative levels of polycyclic aromatic hydrocarbons (PAHs) at a large number of locations over time allowed us to assess the significance and potential source of these compounds in the river. Concentrations of PAH were greatest near urban areas and peaked during the late winter, when streams flows and dilution were low. Vessel activity and PAH levels peaked in July and were heaviest in the lower 16 km of the river, where fishing activity was concentrated. Nearly one-third of the vessels observed on the river were powered by two-stroke engines, which release a higher proportion of unburned fuel into the water than the cleaner burning four-stroke engines. The low concentrations of hydrocarbons upriver of the boat traffic suggest very little remote delivery of these contaminants to the watershed. Polyethylene strips proved to be an excellent, low-cost tool for determining the PAH patterns in a large watershed.
Environmental Toxicology and Chemistry 09/2006; 25(8):2011-7. · 2.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: The effect of various states of weathering (no weathering, 20% evaporatively weathered, and emulsification) on the effectiveness of oil dispersants Corexit 9527 and 9500 in dispersing Alaska North Slope crude oil into the water column was tested under laboratory conditions at a combination of realistic subarctic salinities and temperatures. A modified version of the swirling flask effectiveness test was conducted at temperatures of 3, 10 and 22 °C with salinities of 22‰ and 32‰. Petroleum dispersed into the water column following application of dispersant was measured by gas chromatography with flame ionization detection. Based on comparison of unresolved complex mixtures, dispersants dispersed less than 40% of the fresh oil and less than 10% of the weathered oil and were most effective (25–75%) when used to disperse a stable oil/water emulsion at 10 °C. At the combinations of temperature and salinity most common in the estuaries and marine waters of Alaska, dispersants effectiveness was less than 10%, the detection limits of the tests. The results indicate that oil weathering state, seawater salinity and temperature are important factors affecting dispersant performance, however because our laboratory tests were conducted at low mixing energy, considerable caution should be used in extrapolating these laboratory studies to field conditions.
[show abstract][hide abstract] ABSTRACT: Injury to a species resulting from long-term exposure to low concentrations of pollutants is seldom noted or even tested. One of the products of the Exxon Valdez oil spill was the first report of damage to eggs and larvae of pink salmon (Oncorhynchus gorbuscha) following long-term exposure to low concentrations of weathered crude oil. These life stages were previously thought to be highly resistant to injury from oil. Growth rate among migrating fry was depressed, and the population was reduced via size-dependent mortality. Elevated egg mortality in oiled streams continued for at least 4 years after the spill. Laboratory tests verified that embryos are sensitive to long-term exposure to weathered oil in the low parts per billion range. These results are compared with those of studies conducted by investigators funded by Exxon Corporation and, where controversy exists, we attempt to reconcile the studies. These findings are important to the pink salmon fisheries of Prince William Sound (PWS) and are also broadly applicable to toxicity and impact from nonpoint source pollution of urban estuaries.
Reviews in Fisheries Science - REV FISH SCI. 01/2001; 9(3):165-211.
[show abstract][hide abstract] ABSTRACT: Behavioural preference tests were used to determine if sediment selection played a role in habitat choice. Four species of juvenile pleuronectids were given a choice of eight sediments in a carousel and final choices were recorded after 20 h. Juvenile flatfishes demonstrated strong selection for sediments less than 500 μm. Juvenile starry flounder (Platichthys stellatus) selected larger particles with increasing fish size. Starry flounder under 25 mm in length chose mud, 50–80 mm fish chose mud and mixed mud sediments and larger juveniles (>150 mm) confined themselves to find sand. Juvenile halibut (Hippoglossus stenolepis) at 50–80 mm preferred a combination of mud and fine sand and were spatially segregated. Yellowfin sole (Pleuronectes asper) at 50–80 mm showed a slight preference for mud and mixed mud sediments over sand, a selection that became stronger in larger (>150 mm) fish. Juvenile rock sole (Pleuronectes bilineatus) at 50–80 mm preferred substrata of sand and mixed sand nearly 90% of the time. All species seldom selected sediments which were too coarse to allow the flatfishes to bury themselves, such as granular or pebble substrata. The results of these laboratory studies can be used to predict the distribution of juvenile flatfishes in a nursery area.
Netherlands Journal of Sea Research 01/1995; 34(1):177-182.
[show abstract][hide abstract] ABSTRACT: Behavioural tests were used to determine whether juvenile flatfishes were capable of detecting and avoiding sediment containing various concentrations of petroleum hydrocarbons. Three species of juvenile Alaskan flatfishes: rock sole (Pleuronectes bilineatus), yellowfin sole (P. asper), and Pacific halibut (Hippoglossus stenolepis) were tested in laboratory chambers containing contaminated mud or sand offered in combination with clean mud, sand or granule. The flatfishes were able to detect and avoid heavily oiled (2%) sediment, but they did not avoid lower concentrations of oiled sediment (0.05%). Oiled sediment was favoured over unoiled sediment if the unoiled sediment was of the grain size not preferred by that species. Oiled sand or mud was always preferred unoiled granule. The observed lack of avoidance at concentrations likely to occur in the environment may lead to long-term exposure to contaminated sediment following a spill. Recruitment of juveniles may be affected if the exposure to oil is long enough to affect growth and survival.
[show abstract][hide abstract] ABSTRACT: 1.1. Coho salmon smolts accumulated up to 30 times more hydrocarbon in selected tissues than did coho salmon jacks when exposed to water-soluble fraction of Cook Inlet crude oil.2.2. Aryl hydrocarbon hydroxylase (AHH) activity continued to increase during 12 days of exposure in coho smolts, in contrast to jacks in which AHH activity peaked at 2 days and remained elevated during 20 days of exposure.3.3. Cytochrome P-450 concentrations peaked in 48 hr and returned to control levels in exposed smolts. In exposed and control jacks, cytochrome P-450 decreased during the 20 day experimental period. Concentrations of P-450 were significantly greater, however, in exposed jacks than in control jacks.4.4. Aryl hydrocarbon hydroxylase (AHH) activity and cytochrome P-450 concentrations were greater in non-exposed coho smolts and jacks than in non-exposed pre-spawning adults.5.5. Coho jacks were not as responsive as coho smolts in terms of P-450 induction, however, they were more responsive than anticipated for a fish in a terminal life stage.
Comparative Biochemistry and Physiology Part C: Comparative Pharmacology. 01/1989;
[show abstract][hide abstract] ABSTRACT: The effects of fluctuating diel temperature cycles on survival, growth, plasma cortisol and glucose concentrations, liver weight, and liver glycogen of juvenile coho salmon Oncorhynchus kisutch were determined. Temperature cycles (10-13Â°, 9-15Â°, 8-17Â°, and 6.5-20Â°C) were selected to stimulate observed temperatures in clear-cuts of southeastern Alaska. Different levels of feeding, including starvation, were used in each of the tests. LT50s (peak temperature within a cycle producing 50% mortality) were 28Â°C for age-0 fish (350 mg) and 26Â° for age-II fish (22-g presmolts). Cyclic temperatures for 40 d, averaging 11Â°C daily, did not influence growth of age-0 fish on any food ration as compared to controls held at a constant 11Â°C. Plasma cortisol and glucose concentrations were significantly greater in fish maintained for 20 d in the 6.5-20Â°C cycle but not different in fish in 10-13Â° and 9-15Â° cycles or a constant 11Â°C. These elevated concentrations may be indicators of long-term stress. Plasma cortisol concentrations were lower in starved fish than in fed fish at all temperature regimes; however, fluctuating temperature did not enhance starvation effects on cortisol levels. Diel temperature cycles did not affect liver weights or liver glycogen concentrations.
Transactions of The American Fisheries Society - TRANS AMER FISH SOC. 01/1986; 115(1):52-59.
[show abstract][hide abstract] ABSTRACT: Coho salmon, Oncorhynchus kisutch, fry were exposed for 40 days to stable, sublethal concentrations of toluene (0.4, 0.8, 1.6, 3.2, 5.8 ..mu..l/liter) and naphthalene (0.2, 0.4, 0.7. 1.4 mg/liter) in fresh water. All fry were fed equal daily rations of Oregon Moist Pellet Formula II. Dry weights, wet weights, and lengths of fry exposed to the two highest concentrations of each toxicant for 40 days were significantly less than controls (P < 0.01). Growth per day, determined from weights and lengths, decreased linearly with increased concentrations. Fry exposed to naphthalene had a slower growth rate than fry exposed to equivalent concentrations (percentage of the 96-hour median lethal concentration or LC50) of toluene. Concentrations 18% of the LC50 of naphthalene and 26% of the LC50 of toluene had no effect on dry weight, wet weight, or length of exposed fry.
Transactions of The American Fisheries Society - TRANS AMER FISH SOC. 01/1981; 110(3):430-436.
[show abstract][hide abstract] ABSTRACT: Ninety-six hour toxicity tests were used to determine the sensitivity of various species and life stages of Alaskan freshwater and anadromous fishes to benzene and to the water soluble fraction of Prudhoe Bay crude oil. Threespine sticklebacks, slimy sculpins, and six salmonid species, including coho and pink salmon, were the species tested. Median tolerance limits of salmonids, sticklebacks, and sculpins exposed to benzene and to crude oil were determined. Results show that all salmonid species are more sensitive to benzene and to crude oil than sticklebacks or slimy sculpins are. (1 graph, 24 references, 3 tables)
Transactions of The American Fisheries Society - TRANS AMER FISH SOC. 01/1979; 108(4):408-414.