Survival under the Gravel: the Effects of Egg Size and Parental Identity on the In Situ Hatching Success of Chinook Salmon

2019 ◽  
Vol 148 (5) ◽  
pp. 991-1003 ◽  
Author(s):  
Michael W. Thorn ◽  
Yolanda E. Morbey
Author(s):  
Yuichiro Nishibe ◽  
Tsutomu Ikeda

Egg development time and hatching success were determined for the oncaeid copepod, Triconia canadensis, from the mesopelagic zone of the western subarctic Pacific. The egg development time was estimated to be 74.7–84.5 days at in situ temperature (3°C), which is much longer than those reported previously on the other oncaeid copepods even if the differences in experimental temperatures are taken into account. The egg hatching success varied between 50 and 100%, with a grand mean of 88%. The newly hatched nauplii of T. canadensis were elongate ellipsoid in shape, and had many large-sized lipid droplets in their body. Possible adaptive significance of apparent longer egg developmment time of T. canadensis is discussed in the light of their life cycle strategy.


1983 ◽  
Vol 40 (3) ◽  
pp. 287-297 ◽  
Author(s):  
Karl K. English

Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanich Inlet, B.C. The enclosures permitted ample water and zooplankton circulation while retaining 5–6 g juvenile salmon. Mean growth rate was 1.8% wet body weight/d over 6 wk. Weekly growth rates ranged from 3.9%/d while food was abundant, to −0.5%/d when food was scarce. Zooplankton concentration inside and outside enclosures without fish were not significantly different. Organisms associated with the sides of the enclosures (non-pelagic) were not a major contributor to the growth of the juvenile chinook. There was a strong relationship between the fish growth rates and the abundance of 1.4- to 4.5-mm zooplankton. Rates of successful search varied directly with the size and inherent contrast of a prey item. The minimum rate of successful search was 2.3 m3/h for salmon feeding on 1.4- to 4.5-mm zooplankton. This rate of successful search, while far greater than previously suspected, is still within the visual capabilities of the juvenile salmon. The enclosed salmon grew rapidly on zooplankton concentrations that were 1/1000 of those required to sustain similar growth rates in tank experiments.Key words: predator–prey relationship, planktivorous salmonid, marine, "in situ" enclosures, search efficiency


2004 ◽  
Vol 65 (s1) ◽  
pp. 319-319
Author(s):  
J. E. Joyce ◽  
A. C. Wertheimer ◽  
A. Gray ◽  
F. Thrower
Keyword(s):  

1993 ◽  
Vol 71 (6) ◽  
pp. 1146-1152 ◽  
Author(s):  
Todd W. Arnold

I determined hatching success for 328 dabbling duck (Anas spp.) eggs that were experimentally subjected to varying lengths of preincubation delay and then artificially incubated. Hatchability declined as unincubated eggs were exposed to longer preincubation delays. This effect was more pronounced at higher ambient temperatures and later in the nesting season, but did not vary with egg size or among duck species. These results are largely consistent with observed patterns of clutch-size variation among prairie-nesting waterfowl. Clutch size may be smaller later in the year and at lower latitudes owing to the negative effects of date and temperature on the ability of eggs to withstand preincubation delay. The timing of embryo mortality was bimodal, with peaks occurring during early development (<6 d) and just before hatching (>22 d); however, only early mortality was affected by preincubation delay. Eggs lost up to 2.6% of their initial mass as water vapor during preincubation delay, but the amount of water loss did not affect hatching success. Eggs subjected to preincubation delay required about 1 additional day to hatch. Incubation time was related to egg size in northern shovelers (Anas clypeata) and in all species combined, but not in blue-winged teal (Anas discors) or mallards (Anasplatyrhynchos). These data provide only weak support for the hypothesis that large eggs are costly because they take longer to hatch.


Oryx ◽  
2014 ◽  
Vol 49 (4) ◽  
pp. 677-686 ◽  
Author(s):  
Ohiana Revuelta ◽  
Yolanda M. León ◽  
Annette C. Broderick ◽  
Pablo Feliz ◽  
Brendan J. Godley ◽  
...  

AbstractThe beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively). Our results show that in the west, artificial incubation significantly decreases hatching success in clutches. In the east the duration of incubation is increased, which we predict would result in an increase in the number of males from these clutches. Clutch relocation is currently the only viable conservation option for clutches on eastern beaches because of illegal egg take but action is needed to ensure that the natural sex ratio is not distorted. However, on the western beaches in situ clutch incubation seems possible through beach protection. Further community engagement and enforcement are required to improve conservation measures at eastern beaches if long-term, less sustainable intervention is to be avoided.


2017 ◽  
Vol 8 (1) ◽  
pp. 778-789 ◽  
Author(s):  
Karen M. Cogliati ◽  
Julia R. Unrein ◽  
Heather A. Stewart ◽  
Carl B. Schreck ◽  
David L. G. Noakes

1998 ◽  
Vol 55 (8) ◽  
pp. 1946-1953 ◽  
Author(s):  
Michael T Kinnison ◽  
Martin J Unwin ◽  
William K Hershberger ◽  
Thomas P Quinn

Interpopulation differences in several adult phenotypic traits suggest that New Zealand (NZ) chinook salmon (Oncorhynchus tshawytscha) are evolving into distinct populations. To further investigate this hypothesis, we compared egg sizes, fecundities, and early development rates of chinook from two NZ streams. The two NZ study populations differed in size-adjusted egg weight and gonadosomatic index, but not in size-adjusted fecundity. Egg weight, fecundity, and gonadosomatic index values for both NZ populations were different than values for chinook from Battle Creek, California, the population regarded as the ancestral NZ stock. In contrast, there was little evidence of divergence in juvenile development. Time to hatching did not differ between the two NZ study populations and heritability estimates were small with large standard errors. Evidence of a small difference in alevin growth rate may have represented an effect of yolk conversion mechanics related to egg size. Despite the similarity in development rates under shared conditions, modeling based on temperature records suggests that emergence dates in the two NZ streams may differ by 4-6 weeks, yielding significant phenotypic differences.


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