Parasitism on Juvenile Pacific Salmon (Oncorhynchus) and Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia by the River Lamprey (Lampetra ayresi)

1973 ◽  
Vol 30 (4) ◽  
pp. 565-570 ◽  
Author(s):  
J. F. Roos ◽  
P. Gilhousen ◽  
S. R. Killick ◽  
E. R. Zyblut
Keyword(s):  
Size Range ◽  
Pacific Salmon ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi ◽  
River Lamprey ◽  
Juvenile Pacific Salmon ◽  
Healing Wounds ◽  
Narrow Size Range

River lamprey (Lampetra ayresi) were found to parasitize the young of five species of Pacific salmon (Oncorhynchus) and Pacific herring (Clupea harengus pallasi) in the Strait of Georgia, B.C. The dorsal attachment of the river lamprey is in sharp contrast to the usually ventral attachment of other species of lampreys that parasitize salmonids. Up to 1.9% of young salmon showed evidence of lamprey marks, and marked fish were generally restricted to a narrow size-range. Some of the fish exhibited severe wounds. Evidence from healing wounds on fingerlings and scars on adults indicates that some juvenile salmon survive the attacks of the river lamprey.

Pacific salmon and Pacific herring mortalities in the Fraser River plume caused by river lamprey (Lampetra ayresi)

1995 ◽  
Vol 52 (3) ◽  
pp. 644-650 ◽  
Author(s):  
Richard J. Beamish ◽  
Chrys-Ellen M. Neville
Keyword(s):  
Chinook Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
River Plume ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Abundance Estimates ◽  
River Lamprey

River lamprey (Lampetra ayresi) enter the Strait of Georgia from the Fraser River and feed almost exclusively on Pacific herring (Clupea harengus) and salmon (Oncorhynchus spp.). Although the major prey of river lamprey is Pacific herring, the greater effect of lamprey predation was on the populations of chinook (O. tshawytscha) and coho (O. kisutch) salmon. In 1990 and 1991, river lamprey killed a minimum of 20 million and 18 million chinook salmon, respectively, and a minimum of 2 million and 10 million coho salmon in the same years. In 1991, river lamprey in the Fraser River plume killed an equivalent of approximately 65 and 25% of the total Canadian hatchery and wild production of coho and chinook salmon, respectively. These estimates are probably low because river lamprey also feed in other areas and the abundance estimates are conservative. These high mortality rates indicate that river lamprey predation must be considered as a major source of natural mortality of chinook and coho salmon in the Strait of Georgia.

Alternative Harvest Strategies for Pacific Herring (Clupea harengus pallasi)

1988 ◽  
Vol 45 (5) ◽  
pp. 888-897 ◽  
Author(s):  
D. L. Hall ◽  
R. Hilborn ◽  
M. Stocker ◽  
C. J. Walters
Keyword(s):  
Management Strategies ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Harvest Rate ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi ◽  
Current Management Strategy ◽  
Stock Recruitment ◽  
Spawning Biomass ◽  
Constant Escapement

A simulated Pacific herring (Clupea harengus pallasi) population is used to evaluate alternative management strategies of constant escapement versus constant harvest rate for a roe herring fishery. The biological parameters of the model are derived from data on the Strait of Georgia herring stock. The management strategies are evaluated using three criteria: average catch, catch variance, and risk. The constant escapement strategy provides highest average catches, but at the expense of increased catch variance. The harvest rate strategy is favored for its reduced variance in catch and only a slight decrease in mean catch relative to the fixed escapement strategy. The analysis is extended to include the effects of persistent recruitment patterns. Stock–recruitment analysis suggests that recruitment deviations are autocorrelated. Correlated deviations may cause bias in regression estimates of stock–recruitment parameters (overestimation of stock productivity) and increase in variation of spawning stock biomass. The latter effect favors the constant escapement strategy, which fully uses persistent positive recruitment fluctuations. Mean catch is depressed for the harvest rate strategy, since the spawning biomass is less often located in the productive region of the stock–recruitment relationship. The model is used to evaluate the current management strategy for Strait of Georgia herring. The strategy of maintaining a minimum spawning biomass reserve combines the safety of the constant escapement strategy and the catch variance reducing features of the harvest rate strategy.

Environmental Variation and Recruitment of Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia

1985 ◽  
Vol 42 (S1) ◽  
pp. s174-s180 ◽  
Author(s):  
Max Stocker ◽  
Vivian Haist ◽  
David Fournier
Keyword(s):  
Environmental Variables ◽  
River Discharge ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi ◽  
Age Structured ◽  
Age Structured Model ◽  
The Relationship ◽  
Spawning Success

We used an age-structured model to estimate recruitment for the Strait of Georgia Pacific herring (Clupea harengus pallasi) population. The model used for herring is a version of the model described in Fournier and Archibald (1982. Can. J. Fish. Aquat. Sci. 39: 1195–1207), modified to include spawn survey information. Three structural assumptions are made to include the spawn data: (1) the form of the relationship between the actual spawn and the observed spawn, (2) the form of the relationship between escapement and actual spawn, and (3) the existence of a Ricker spawn–recruitment relationship, with a multiplicative environmental component. In order to determine which environmental factors had a significant effect on recruitment, we attempted to explain the residual variation from the Ricker curve with the environmental variables using exploratory correlations. Temperature, river discharge, sea level, and sunlight were examined. A multiplicative, environmental-dependent Ricker spawn–recruitment model was used to identify significant environmental variables. The model suggests a significant dome-shaped relationship between temperature and spawning success with an optimal temperature during larval stages resulting in maximum production of recruits. Also, increased spawning success is associated with increased summer river discharge. The significant environmental variables were included in the age-structured model in a stock–environment–recruitment relationship, and all model parameters were reestimated. The overall model fit improved only marginally with the inclusion of environmental variables, as indicated by the objective function value. However, the S–R component of the objective function dropped by 23% when environmental variables were included.

Growth and Maturation of Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia

1985 ◽  
Vol 42 (S1) ◽  
pp. s138-s146 ◽  
Author(s):  
V. Haist ◽  
M. Stocker
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Clupea Harengus ◽  
Sea Surface ◽  
Pacific Herring ◽  
Juvenile Growth ◽  
Strait Of Georgia ◽  
Surplus Energy ◽  
Clupea Harengus Pallasi ◽  
Stock Biomass

Juvenile growth rate, adult surplus energy, and the maturation schedule for the Strait of Georgia Pacific herring (Clupea harengus pallasi) stock were investigated over the period 1950–81. The variance in weight at age 2 is largely accounted for by juvenile abundance and sea surface temperature, indicating density-dependent juvenile growth moderated by environmental factors. Density and environmental factors have been equally important in moderating juvenile growth. Yearly variation in maturation of 3-yr-old herring is related to their average length; however, in two of the eight years studied the 3-yr-olds matured at considerably smaller sizes. The variance in adult surplus energy (growth plus gonad production) was largely accounted for by body weight, adult biomass, and sea surface temperature. A dome-shaped relationship between surplus energy and biomass was indicated, suggesting that over a broad range of population size, adult surplus energy is not density dependent. The relationship of sea surface temperature to both juvenile growth and adult surplus energy was quadratic with an optimum value. Recruitment biomass has been a relatively larger component than adult production of total stock growth, particularly during the period of high fishing intensity. This resulted in large fluctuations in stock biomass; in recent years, with lower fishing intensity, adult production has been a larger component of stock growth, and the stock biomass has become more stable.

An Evaluation of Morphometrics and Meristics for Stock Separation of Pacific Herring (Clupea harengus pallasi)

1984 ◽  
Vol 41 (3) ◽  
pp. 414-422 ◽  
Author(s):  
Hans Jürg Meng ◽  
Max Stocker
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Function Analysis ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Geographic Scale ◽  
Meristic Characters ◽  
Morphometric Characters ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi

We conducted an analysis to determine if Pacific herring (Clupea harengus pallasi) stocks occurring in different localities in British Columbia waters could be separated using morphometric and meristic characters. Discriminant function analysis was applied to morphometric and meristic characters taken from food herring samples. Herring found in northern British Columbia waters were detectably different from those found in the Strait of Georgia. We recommend using meristic characters for separation on a broad geographic scale and using "best" morphometric characters for finer resolution within the established broader groups. We defined a set of 12 best morphometric characters for further large-scale studies.

Biological Basis of Maturation and Spawning Waves in Pacific Herring (Clupea harengus pallasi)

1989 ◽  
Vol 46 (10) ◽  
pp. 1776-1784 ◽  
Author(s):  
D. M. Ware ◽  
R. W. Tanasichuk
Keyword(s):  
Interannual Variation ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Sea Temperature ◽  
Instantaneous Rate ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi ◽  
Maturation Rate ◽  
Spawning Time ◽  
Timing Of Spawning

Maturation rates (measured as the change in the gonosomatic index (GSI) with time) over the last month of the annual maturation cycle were estimated for male and female herring in British Columbia, between 1982–87. The data were analyzed to determine interannual and interregional differences in the maturation rate and its influence on spawning time. The data also indicated that in some areas herring spawned in discrete waves — the largest fish tended to spawn first and the smaller fish in subsequent waves. Each spawning wave lasted about 5–6 d and the interwave interval varied from 8–26 d in the Strait of Georgia. General equations were developed to describe gonadal growth over the entire maturation cycle. These equations accounted for the observed differences in: (1) the maturation rates between the sexes (males initially mature faster), (2) the interregional and interannual variation in the timing of spawning (herring tend to spawn later at higher latitudes, and earlier than normal when its warmer), and (3) provide an explanation for spawning waves. All of these phenomena derive from the fact that the instantaneous rate at which the gonad grows during the maturation cycle in both sexes depends on the weight of the fish, and the daily sea temperature.

Tidal Influence on Spawning Time of Pacific Herring (Clupea harengus pallasi

1990 ◽  
Vol 47 (12) ◽  
pp. 2390-2401 ◽  
Author(s):  
D. E. Hay
Keyword(s):  
Size Composition ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Strait Of Georgia ◽  
Tidal Influence ◽  
Clupea Harengus Pallasi ◽  
Spawning Areas ◽  
Spawning Time ◽  
New Moon ◽  
Calendar Dates

Dates of over 17 000 records of Pacific herring (Clupea harengus pallasi) spawns from 1951 to 1986 in British Columbia were examined by tidal or lunar phases. The frequency of spawns was significantly higher during neap tides following a new moon. The effect was greatest in spawning areas close to the open Pacific and least in the inside waters of the Strait of Georgia. The mechanism of tidal influence on spawning is uncertain but may involve inhibition of spawning during periods of strong spring tides corresponding to periods of full and new moons. An association between spawning time and tidal phases requires that the annual calendar dates of spawning times change between years. A tidal cycle (or a synodic month) is about 29.6 d, and 12 synodic mo equals 355.4 d, whereas a calendar year is about 365.2 d. Therefore, the dates of tidal phases, such as the springtide, are either about 10 d earlier or 5 d later relative to the previous year. Other possible consequences of tidal influence include the timing of spawning waves and differences in size composition and egg size between waves.

Fixation Shrinkage of Herring Larvae: Effects of Salinity, Formalin Concentration, and Other Factors

1982 ◽  
Vol 39 (8) ◽  
pp. 1138-1143 ◽  
Author(s):  
D. E. Hay
Keyword(s):  
Clupea Harengus ◽  
Pacific Herring ◽  
Larval Size ◽  
Factors Affecting ◽  
Clupea Harengus Pallasi

The most important factors affecting the degree of larval shrinkage of Pacific herring (Clupea harengus pallasi) larvae during fixation are the salinity and formalin concentrations and initial larval size. In low formalin concentrations (2–5% formalin) shrinkage increased from less than 2% shrinkage at low salinities to about 10% shrinkage in seawater formalin. In high formalin concentrations (20–30% formalin) shrinkage was fairly uniform, ranging from about 3% shrinkage in low salinities to about 5% in seawater. Shrinkage in fixatives stored at 0, 5, 10, 20, and 30 °C was slightly higher (1–2%) at the higher temperatures. Buffering agents and starvation had no effect on shrinkage. Small, young larvae shrank relatively more than larger older larvae.Key words: herring larvae, fixation, shrinkage, formalin, salinity

scholarly journals Historical Diets of Forage Fish and Juvenile Pacific Salmon in the Strait of Georgia, 1966–1968

2016 ◽  
Vol 8 (1) ◽  
pp. 580-594 ◽  
Author(s):  
Geoffrey J. Osgood ◽  
Laura A. Kennedy ◽  
Jessica J. Holden ◽  
Eric Hertz ◽  
Skip McKinnell ◽  
...  
Keyword(s):  
Pacific Salmon ◽  
Forage Fish ◽  
Strait Of Georgia ◽  
Juvenile Pacific Salmon
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