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

2007 ◽  
Keyword(s):  
Chum Salmon ◽  
Oncorhynchus Keta ◽  
Major Influence ◽  
Time Interval ◽  
Daily Mortality ◽  
Demographic Modeling ◽  
Northeast Pacific ◽  
Marine Habitats ◽  
Regional Comparisons ◽  
Northeast Pacific Ocean

Abstract.—Interannual variability in chum salmon <em>Oncorhynchus keta </em>mortality during early marine life is thought to have a major influence on recruitment. However, few estimates of daily mortality are available for chum salmon during this period, and average values reported in the literature are unrealistically high when used in a simple life-history model. We analyzed survival to adult of seven groups of chum salmon, marked as juveniles, and released at different times and sizes at Little Port Walter, Alaska to estimate average daily mortality during early marine residency for an early emigration group and a late emigration group. We assumed that differences in proportions of groups surviving to adult between the initial releases of unfed fry and subsequent releases of fed fry for each group were due to natural mortality during the time interval between releases. For both groups, mortality was highest during the period immediately after release, declining rapidly thereafter. Average daily mortality was 8.1% for the early release during their first 21d in the ocean and 3.9% for the late release during the first 32 d in the ocean. After May 4 (54 d and 33 d postrelease, respectively, for the early and late groups), average daily mortality was less than 0.6% for both groups. These results support the paradigm that most of the mortality of chum salmon in the ocean occurs early in their marine residency, and the results provide realistic rates for demographic modeling of the abundance of chum salmon in marine habitats.

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

2007 ◽  
Keyword(s):  
Coastal Waters ◽  
Pacific Salmon ◽  
Size Class ◽  
Small Fish ◽  
Lepeophtheirus Salmonis ◽  
Northeast Pacific ◽  
Salmon Lice ◽  
Regional Comparisons ◽  
Northeast Pacific Ocean ◽  
Over Time

Abstract.—We report patterns of infestation with motile salmon lice, <em>Lepeophtheirus salmonis</em>, on Pacific salmon collected with a surface trawl in coastal waters of Oregon, Washington, British Columbia, and Alaska during 2002 and 2003. Salmon lice were observed on all salmon species examined and in all areas surveyed. The prevalence and abundance of lice infestation varied significantly among species, size-classes, seasons, regions, and years, with larger salmon being consistently more heavily infested than small salmon. The number of lice infesting the small size-class (100–400 mm) of salmon rarely exceeded 5 lice per fish with a mean abundance generally below 0.2 lice per fish. Lice prevalence and, to a lesser extent, lice abundance increased over time in small fish, with lower values during spring and higher values in the following winter, and continued to increase in larger and older fish. There were no apparent effects of water temperature on lice infestation in Pacific salmon. This study suggested that salmon infested with lice remained in coastal waters throughout the year. We suggest that lice on salmon that overwinter in coastal waters will contribute to a pool of infective copepodids in these habitats.

Fecundity of coho salmon (Oncorhynchus kisutch) and chum salmon (O. keta) in the northeast Pacific Ocean

1982 ◽  
Vol 60 (6) ◽  
pp. 1463-1469 ◽  
Author(s):  
Terry D. Beacham
Keyword(s):  
British Columbia ◽  
Chum Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Vancouver Island ◽  
Northeast Pacific ◽  
Queen Charlotte Islands ◽  
Kodiak Island ◽  
Salmon Stock ◽  
Northeast Pacific Ocean

Significant regional and annual variability in fecundity of coho salmon (Oncorhynchus kisutch) and chum salmon (O. keta) in British Columbia was detected during this investigation. A Kodiak Island (Alaska) coho salmon stock was more fecund than southern stocks in British Columbia and Washington. Fecundity ranged from 2450 to 2850 eggs per female at 53.6 cm postorbital–hypural length for Vancouver Island stocks to over 4400 eggs per female for a Kodiak Island stock at the same length. Chum stocks on Vancouver Island and the Queen Charlotte Islands generally had fecundities less than 3200 eggs per female at 58.8 cm postorbital–hypural length, whereas chum of equal lengths in mainland British Columbia stocks ranged from 3200 to 3450 eggs per female. Older chum and coho were usually more fecund than younger ones, but this difference could be accounted for by differences in mean length-at-age, fecundity being related to body size.

Early Marine Mortality of Marked Juvenile Chum Salmon (Oncorhynchus keta) Released into Hood Canal, Puget Sound, Washington, in 1980

1983 ◽  
Vol 40 (4) ◽  
pp. 426-435 ◽  
Author(s):  
Nicholas J. Bax
Keyword(s):  
Chum Salmon ◽  
Pink Salmon ◽  
Puget Sound ◽  
Oncorhynchus Keta ◽  
Daily Mortality ◽  
Chum Salmon Oncorhynchus Keta ◽  
Hood Canal ◽  
Time Period ◽  
Order Of Magnitude ◽  
Juvenile Chum Salmon

The average daily loss in numbers from a group of fluorescently marked, hatchery-reared, juvenile chum salmon (Oncorhynchus keta) remaining in the nearshore zone following their release from the hatchery into southern Hood Canal, Washington State, was estimated at 38–49%. This estimated loss was then adjusted by the estimated maximum emigration of marked fish from the sampling area and the average daily mortality over a 2- and a 4-d time period estimated at between 31 and 46%. These estimates are an order of magnitude higher than estimates of the average daily mortality of naturally emigrating juvenile pink salmon (O. gorbuscha) from the Bella Coola River, British Columbia, over a 40-d time period (Parker 1968). The two studies are contrasted and it is suggested that daily mortality is highly variable over the 40 d subsequent to saltwater entry, with mortality higher initially, particularly for those fish remaining close to their point of saltwater entry.

scholarly journals Southward decrease in the protection of persistent giant kelp forests in the northeast Pacific

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Nur Arafeh-Dalmau ◽  
Kyle C. Cavanaugh ◽  
Hugh P. Possingham ◽  
Adrian Munguia-Vega ◽  
Gabriela Montaño-Moctezuma ◽  
...  
Keyword(s):  
Baja California ◽  
Marine Reserves ◽  
Fold Increase ◽  
Kelp Forests ◽  
Giant Kelp ◽  
Central California ◽  
Northeast Pacific ◽  
The Face ◽  
High Resolution Satellite Imagery ◽  
Northeast Pacific Ocean

AbstractKelp forests are globally important and highly productive ecosystems, yet their persistence and protection in the face of climate change and human activity are poorly known. Here, we present a 35-year time series of high-resolution satellite imagery that maps the distribution and persistence of giant kelp (Macrocystis pyrifera) forests along ten degrees of latitude in the Northeast Pacific Ocean. We find that although 7.7% of giant kelp is protected by marine reserves, when accounting for persistence only 4% of kelp is present and protected. Protection of giant kelp decreases southerly from 20.9% in Central California, USA, to less than 1% in Baja California, Mexico, which likely exacerbates kelp vulnerability to marine heatwaves in Baja California. We suggest that a two-fold increase in the area of kelp protected by marine reserves is needed to fully protect persistent kelp forests and that conservation of climate-refugia in Baja California should be a priority.

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