The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Fish Assemblages ◽  
Pacific Salmon ◽  
California Current ◽  
Minor Component ◽  
Species Group ◽  
Juvenile Salmon ◽  
Species Assemblages ◽  
Coastal Species ◽  
Night And Day ◽  
Associated Species

Abstract.—We compared epipelagic fish assemblages associated with juvenile (ocean-age 0) Pacific salmon <em>Oncorhynchus </em>spp. from neritic waters of the California Current and Alaska Current regions in the spring–summer and summer–fall periods of 2000–2004. Catches originated from rope trawl surveys conducted between latitudes 37°N and 60°N and spanned more than 1,100 km in the coastal and inshore habitats of each region. Catch data were used from the epipelagic sampling of waters from near surface to depths of about 18 m, primarily over the continental shelf. Catch composition, frequency of occurrence, and density were evaluated between regions and habitats for day sampling. Diel (night and day) catch comparisons were also made at a few localities in each region. In day catches from both regions, a total of 1.69 million fish and squid representing 52 fish families and 118 fish species were sampled from 2,390 trawl hauls. Ninety-seven percent of the daytime catch was composed of 11 fish families and squid in coastal and inshore habitats of each region: clupeids dominated catches in the California Current (72% and 76% of catch, respectively), and salmonids dominated catches in the Alaska Current (46% and 62% of catch, respectively). Juveniles comprised 81–99% of salmon sampled in both coastal and inshore habitats of each region. Frequencies of occurrence were highest for juvenile salmon in both regions, but average densities were highest for Pacific herring <em>Clupea pallasii </em>and Pacific sardine <em>Sardinops sagax </em>in the California Current region. Cluster analyses revealed distinct geographic breakpoints in coastal species assemblages off central Vancouver Island and in inshore species assemblages in southeastern Alaska. Species were found to cluster into six groups from coastal localities and four groups from inshore localities. Indicator species analysis and nonmetric multidimensional scaling revealed that most species of juvenile salmonids were located in northern localities. Although juvenile salmon had the most uniform distribution of any species group, their densities relative to associated species were dramatically lower in the California Current, suggesting a higher degree of interactions between juvenile salmon and other species in this region. Diel comparisons in both regions indicated substantially higher catches at night, particularly of clupeids, osmerids, and gadids. Salmonids were a relatively minor component of the night catch in both regions due to dramatic diel shifts in community structure. Additional study of diel interactions of juvenile salmon and associated species is needed to quantify habitat utilization dynamics in marine ecosystems.

Reconstructing habitat use by juvenile salmon sharks links upwelling to strandings in the California Current

2015 ◽  
Vol 525 ◽  
pp. 217-228 ◽  
Author(s):  
AB Carlisle ◽  
SY Litvin ◽  
EL Hazen ◽  
DJ Madigan ◽  
KJ Goldman ◽  
...  
Keyword(s):  
Habitat Use ◽  
California Current ◽  
Juvenile Salmon

Fish assemblages in the Southern California Current: relationships with climate, 1951-2008

2013 ◽  
Vol 22 (3) ◽  
pp. 207-219 ◽  
Author(s):  
J. Anthony Koslow ◽  
Ralf Goericke ◽  
William Watson
Keyword(s):  
Southern California ◽  
Fish Assemblages ◽  
California Current

scholarly journals Do beaver dams reduce habitat connectivity and salmon productivity in expansive river floodplains?

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2403 ◽  
Author(s):  
Rachel L. Malison ◽  
Kirill V. Kuzishchin ◽  
Jack A. Stanford
Keyword(s):  
Fish Assemblages ◽  
Coho Salmon ◽  
Fish Passage ◽  
Main Channel ◽  
Habitat Connectivity ◽  
Juvenile Salmon ◽  
Negative Consequences ◽  
Alluvial Rivers ◽  
Beaver Ponds ◽  
Beaver Dams

Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3–12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99–1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically could produce 2× the biomass (between June–August, 1,174 vs. 667 kg) and rear 3× the number of salmon (370,000 vs. 140,000) compared to the existing condition with dams present. The highly productive Kol river produces an order of magnitude more salmon biomass and rears 40× the individuals compared to the Kwethluk. If beavers were introduced to the Kol River, we estimate that off-channel habitats would produce half as much biomass (2,705 vs. 5,404 kg) and 3× fewer individuals (1,482,346 vs. 4,856,956) owing to conversion of inter-connected, productive springbrooks into inaccessible pond complexes. We concluded that beaver dams may limit the total amount of floodplain habitat available for salmon rearing in the Kwethluk river and that the introduction of beavers to the Kol river could be detrimental to salmon populations. The introduction of beavers to other large alluvial rivers like those found in Kamchatka could have negative consequences for salmon production.

scholarly journals Demersal fish assemblages and habitat characteristics on the continental shelf and upper slope of the north-western Mediterranean

2000 ◽  
Vol 80 (6) ◽  
pp. 981-988 ◽  
Author(s):  
Montserrat Demestre ◽  
Pilar Sánchez ◽  
Pere Abelló
Keyword(s):  
Continental Shelf ◽  
Fish Species ◽  
Fish Assemblages ◽  
Demersal Fish ◽  
Western Mediterranean ◽  
Habitat Characteristics ◽  
Species Assemblages ◽  
The North ◽  
Benthic Sediments ◽  
Upper Slope

Continental shelf and upper slope fish communities were studied along the Catalan coast based on 66 experimental bottom otter trawls. A total of 79 demersal fish species were studied by means of cluster analysis and multi-dimensional scaling (MDS) ordination for community structure. Analysis revealed the existence of five major location clusters. Similarity percentage analysis (SIMPER) was determined by comparing the dissimilarity between two groups of samples using the discriminating species. Geomorphological characteristics, bottom substratum and depth showed direct influences on species assemblages. High correlation between the biotic data samples and depth was observed. The fish species assemblages identified five main demersal fish associations which corresponded with the five location clusters and with five benthic sediments (mud of the upper slope, sand and gravel, mud of the shelf, muddy-sand and sand with rocky outcrops).

The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Gulf Of Alaska ◽  
Juvenile Salmon ◽  
Stomach Fullness ◽  
Feeding Intensity ◽  
Percentage Weight ◽  
Juvenile Pacific Salmon ◽  
Survival Patterns

Abstract.—Upon entering marine waters, juvenile Pacific salmon <em>Oncorhynchus </em>spp. depend on feeding at high and sustained levels to achieve growth necessary for survival. In the last decade, several concurrent studies have been examining the food habits and feeding intensity of juvenile Pacific salmon in the shelf regions from California to the northern Gulf of Alaska. In this paper, we compared results from feeding studies for all five species of juvenile salmon (Chinook salmon <em>O. tshawytscha</em>, coho salmon <em>O. kisutch</em>, chum salmon <em>O. keta, </em>sockeye salmon <em>O. nerka</em>, and pink salmon <em>O. gorbuscha</em>) between 2000 and 2002, years when these regions were sampled extensively. Within these years, we temporally stratified our samples to include early (May–July) and late (August–October) periods of ocean migration. Coho and Chinook salmon diets were most similar due to a high consumption of fish prey, whereas pink, chum, and sockeye salmon diets were more variable with no consistently dominant prey taxa. Salmon diets varied more spatially (by oceanographic and regional factors) than temporally (by season or year) in terms of percentage weight or volume of major prey categories. We also examined regional variations in feeding intensity based on stomach fullness (expressed as percent body weight) and percent of empty or overly full stomachs. Stomach fullness tended to be greater off Alaska than off the west coast of the United States, but the data were highly variable. Results from these comparisons provide a large-scale picture of juvenile salmon feeding in coastal waters throughout much of their range, allowing for comparison with available prey resources, growth, and survival patterns associated with the different regions.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
Species Composition ◽  
Human Population ◽  
Fish Assemblages ◽  
Pacific Salmon ◽  
Large River ◽  
Life Cycles ◽  
Fish Assemblage Structure ◽  
River Region ◽  
Major Industry ◽  
Mackenzie River

<em>Abstract.</em>—The Mackenzie River is the second longest river in North America and drains 1.8 × 10<sup>6</sup> km<sup>2</sup>. of Arctic and sub-Arctic Canada. Thirty-eight fish species have been recorded in the lower Mackenzie River. These species represent a unique mixture of fishes from the Beringian and Agassisian refugia. Many of the species important for subsistence and commercial fisheries in the lower Mackenzie River have complex life cycles and undertake long migrations to spawn, rear, and overwinter. The lower Mackenzie River is a relatively pristine environment with no dams or major industry, a low human population, and species only lightly harvested. This explains why the species composition is relatively stable. However, recently, the effects of climate change may be starting to influence the species composition in terms of greater frequency of rare species such as Pacific salmon. Moreover, a major gas pipeline proposed for the lower Mackenzie River region will probably disturb the fish assemblage structure.

scholarly journals Climate vulnerability assessment for Pacific salmon and steelhead in the California Current Large Marine Ecosystem

PLoS ONE ◽  
2019 ◽  
Vol 14 (7) ◽  
pp. e0217711 ◽  
Author(s):  
Lisa G. Crozier ◽  
Michelle M. McClure ◽  
Tim Beechie ◽  
Steven J. Bograd ◽  
David A. Boughton ◽  
...  
Keyword(s):  
Vulnerability Assessment ◽  
Pacific Salmon ◽  
Marine Ecosystem ◽  
California Current ◽  
Large Marine Ecosystem ◽  
Climate Vulnerability

Effects of temperature change on demersal fishes in the California Current: a bioenergetics approach

2009 ◽  
Vol 66 (9) ◽  
pp. 1449-1461 ◽  
Author(s):  
Chris J. Harvey
Keyword(s):  
Temperature Change ◽  
Fish Assemblages ◽  
Global Climate ◽  
California Current ◽  
Energy Budgets ◽  
Spiny Dogfish ◽  
Temperature Sensitive ◽  
Feeding Rates ◽  
Anoplopoma Fimbria ◽  
Size At Age

Diverse fish assemblages should feature a range of biological and ecological responses to temperature change. Using preliminary bioenergetics models, I simulated growth and maturation of three California Current groundfish (yelloweye rockfish ( Sebastes ruberrimus ), sablefish ( Anoplopoma fimbria ), and spiny dogfish ( Squalus acanthias )) at fixed temperatures ranging from 5 °C to 11 °C. I examined three response variables (size at age 1 (W1), age at 50% maturity (τ50%), and total prey consumption (C)). Yelloweye rockfish responded most strongly for W1, which increased 496% as temperature increased from 5 °C to 11 °C. Spiny dogfish τ50% was highly sensitive, declining from >48 years at 5 °C to <13 years at 11 °C. Age-specific C was most responsive in yelloweye rockfish, increasing by more than fivefold over the range of temperatures, although sablefish likely have greater community-wide impact because their trophic level and absolute feeding rates are higher. Regime shifts, temperature anomalies, or global climate change may directly affect fish energy budgets, elicit range shifts, or produce complex ecological interactions. Studies like this will help managers to identify temperature-sensitive species and anticipate potential changes in populations and diverse communities.

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