Comparison of fecundity-length-latitude relationships between nonanadromous (kokanee) and anadromous sockeye salmon (Oncorhynchus nerka)

2000 ◽  
Vol 78 (10) ◽  
pp. 1791-1805 ◽  
Author(s):  
M D McGurk
Keyword(s):  
Body Size ◽  
Egg Size ◽  
Sockeye Salmon ◽  
Environmental Gradients ◽  
Oncorhynchus Nerka ◽  
Latitudinal Gradients ◽  
Egg Number ◽  
Latitudinal Clines ◽  
Regression Slopes ◽  
Highly Correlated

This study compared fecundity-length-latitude relationships between 25 kokanee populations (15 natural and 10 introduced) and 48 sockeye salmon populations. Significant differences confirmed the hypothesis that the two Oncorhynchus nerka variants follow different reproductive strategies: (i) fecundity is more highly correlated with length for kokanee than for sockeye salmon; (ii) kokanee have higher fecundity-length regression slopes and lower intercepts than sockeye salmon; (iii) kokanee populations share a common fecundity-length regression slope, but sockeye salmon populations do not; and (iv) average lengths and fecundities of kokanee decrease with increasing latitude, but those of sockeye salmon do not. The first three findings confirm that kokanee maintain a constant egg size while increasing egg number with increasing body size but that sockeye salmon increase both egg number and egg size with increasing body size. Kokanee egg sizes may be less variable than those of sockeye salmon because kokanee have lower and less variable energetic costs of spawning migration and tend to use spawning gravel with smaller and less variable particle sizes. Latitudinal clines in kokanee length and fecundity may reflect latitudinal gradients in temperature and duration of the growing season. Such environmental gradients may explain why kokanee populations are rarely found as far north as Alaska.

Fecundity and Egg Retention of Some Sockeye Salmon (Oncorhynchus nerka) Stocks in British Columbia

1986 ◽  
Vol 43 (8) ◽  
pp. 1643-1655 ◽  
Author(s):  
J. I. Manzer ◽  
I. Miki
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Absolute Fecundity ◽  
Egg Retention ◽  
Inadequate Sample Size ◽  
Egg Number ◽  
The Mean ◽  
The Relationship ◽  
Individual Fecundity

The fecundity and egg retention of anadromous female sockeye salmon (Oncorhynchus nerka) collected during 1971–82 from several stocks in British Columbia undergoing controlled fertilization to enhance adult sockeye production were examined. The relationship between egg number and postorbital–hypural length based on 863 females representing 14 stocks was not consistent between all age-types, stocks, and years, probably because of inadequate sample size in some instances. Combined samples, however, revealed a significant positive relationship between postorbital–hypural length and egg number for age 1.2, 1.3, and 2.2 females. Mean absolute fecundity for the respective age-types was 3218, 4125, and 3544 eggs. For samples of 10 or more females, significant stock and annual differences were detected when individual mean absolute fecundity was adjusted to a postorbital–hypural length of 447 mm, but not for females of different age. A comparison of mean fecundities for coastal stocks with historical data for interior British Columbia stocks suggests that coastal stocks are 18% more fecund than interior stocks. Possible causal mechanisms for this regional difference are hypothesized. Examination of 796 carcasses (representing five stocks) for egg retention revealed a range from totally spawned to totally unspawned females, with 56% of the carcasses containing 20 eggs or less and 68% containing 50 eggs or less. The mean egg retention based on all samples combined was estimated to be 6.5% of the mean individual fecundity. This value was reduced to 3.9% when stock means were averaged.

scholarly journals Environmental and ecological factors mediate taxonomic composition and body size of polyplacophoran assemblages along the Peruvian Province

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Christian M. Ibáñez ◽  
Melany Waldisperg ◽  
Felipe I. Torres ◽  
Sergio A. Carrasco ◽  
Javier Sellanes ◽  
...  
Keyword(s):  
Body Size ◽  
Species Composition ◽  
Size Structure ◽  
Environmental Gradients ◽  
Ecological Factors ◽  
Taxonomic Composition ◽  
Latitudinal Gradients ◽  
Size Segregation ◽  
Biogeographic Patterns ◽  
Diversity Gradient

Abstract Intertidal communities’ composition and diversity usually exhibit strong changes in relation to environmental gradients at different biogeographical scales. This study represents the first comprehensive diversity and composition description of polyplacophoran assemblages along the Peruvian Province (SE Pacific, 12°S–39°S), as a model system for ecological latitudinal gradients. A total of 4,775 chitons from 21 species were collected on twelve localities along the Peruvian Province. This sampling allowed us to quantitatively estimate the relative abundance of the species in this assemblage, and to test whether chitons conform to elementary predictions of major biogeographic patterns such as a latitudinal diversity gradient. We found that the species composition supported the division of the province into three ecoregional faunal groups (i.e. Humboldtian, Central Chile, and Araucanian). Though chiton diversity did not follow a clear latitudinal gradient, changes in species composition were dominated by smaller scale variability in salinity and temperature. Body size significantly differed by ecoregions and species, indicating latitudinal size-structure assamblages. In some localities body size ratios differed from a random assemblage, evidencing competition at local scale. Changes in composition between ecoregions influence body size structure, and their overlapping produce vertical size segregation, suggesting that competition coupled with environmental conditions structure these assemblages.

scholarly journals Determinants of life-history traits in a fish ectoparasite: a hierarchical analysis

Parasitology ◽  
2011 ◽  
Vol 138 (7) ◽  
pp. 848-857 ◽  
Author(s):  
G. LOOT ◽  
N. POULET ◽  
S. BROSSE ◽  
L. TUDESQUE ◽  
F. THOMAS ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Egg Size ◽  
Life History Traits ◽  
Abiotic Factors ◽  
Individual Characteristics ◽  
Trade Off ◽  
Individual Fitness ◽  
Parasite Number ◽  
Egg Number

SUMMARYObjective. Unravelling the determinants of parasite life-history traits in natural settings is complex. Here, we deciphered the relationships between biotic, abiotic factors and the variation in 4 life-history traits (body size, egg presence, egg number and egg size) in the fish ectoparasite Tracheliastes polycolpus. We then determined the factors affecting the strength of the trade-off between egg number and egg size. Methods. To do so, we used 4-level (parasite, microhabitat, host and environment) hierarchical models coupled to a field database. Results. Variation in life-history traits was mostly due to individual characteristics measured at the parasite level. At the microhabitat level (fins of fish hosts), parasite number was positively related to body size, egg presence and egg number. Higher parasite number on fins was positively associated with individual parasite fitness. At the host level, host body size was positively related to the individual fitness of the parasite; parasites were bigger and more fecund on bigger hosts. In contrast, factors measured at the environmental level had a weak influence on life-history traits. Finally, a site-dependent trade-off between egg number and egg size existed in this population. Conclusion. Our study illustrates the importance of considering parasite life-history traits in a hierarchical framework to decipher complex links between biotic, abiotic factors and parasite life-history traits.

Intraspecific variation in reproductive effort by female Parapediasia teterrella (Lepidoptera: Pyralidae) and its relation to body size

1990 ◽  
Vol 68 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Larry D. Marshall
Keyword(s):  
Life History ◽  
Body Size ◽  
Egg Production ◽  
Egg Size ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Parameters ◽  
Trade Offs ◽  
Egg Number ◽  
Lepidoptera Pyralidae

Daily egg production of the moth Parapediasia teterrella declined over the life-span of the female but egg size remained constant. The absence of water resulted in lower fecundity and early mortality. Egg size and lifetime fecundity showed considerable inter-individual variation and large females produced more and larger eggs than their smaller counterparts. Large females expended greater reproductive effort than small females. Hatching success was negatively related to egg size. In spite of this, large females laying large eggs had higher fitness than small females. I postulate that multiple reproductive strategies within a species, resulting from differences in reproductive effort expended, may explain why expected trade-offs in reproductive parameters (e.g., egg size versus egg number) were not found in this species. Furthermore, I argue that the prevalent interpretation of life-history evolution (that body size is the important determining parameter of life-history parameters) may reflect correlation of body size with reproductive effort, and reproductive effort may be more important in determining the nature of trade-offs between reproductive parameters.

Genetic Differences in the Early Development and Growth of Sympatric Sockeye Salmon and Kokanee (Oncorhynchus nerka), and their Hybrids

1990 ◽  
Vol 47 (11) ◽  
pp. 2250-2260 ◽  
Author(s):  
Chris C. Wood ◽  
Chris J. Foote
Keyword(s):  
Egg Size ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Genetic Effect ◽  
Genetic Differences ◽  
Hybrid Progeny ◽  
Yolk Absorption ◽  
The Difference ◽  
Male Genotype ◽  
Better Than

Anadromous (sockeye salmon) and nonanadromous (kokanee) Oncorhynchus nerka spawn sympatrically yet appear genetically distinct in a number of rivers in British Columbia. To investigate whether genetic differences are maintained by selection against -hybrid" progeny, we raised pure and reciprocal crosses of Shuswap River sockeye and kokanee under controlled hatchery conditions. Sockeye eggs were larger and survived slightly better than kokanee eggs, regardless of male type, both to the eyed egg stage and as young fry. We observed no differences in survival among cross types during the remainder of the 460 d study. Rate of yolk absorption was similar in pure sockeye and pure kokanee alevins, but significantly faster in alevins sired by sockeye than those sired by kokanee. This indicates a male genetic effect which compensates for the difference in egg size. Hybrid alevins developed differently because egg size is mismatched with the male genotype. Growth rates of fry were significantly more variable within pure kokanee families than within pure sockeye families Hybrid crosses survived as well as pure crosses under the study conditions. However, any progeny resulting from hybrid crosses in nature may sustain higher mortality than those from pure crosses.

Identification of Sockeye Salmon (Oncorhynchus nerka) Stocks in the Stikine River Based on Egg Size Measurements

1985 ◽  
Vol 42 (11) ◽  
pp. 1696-1701 ◽  
Author(s):  
P. C. Craig
Keyword(s):  
Body Weight ◽  
Egg Size ◽  
Sockeye Salmon ◽  
Pattern Analysis ◽  
Oncorhynchus Nerka ◽  
Egg Mass ◽  
Stock Identification ◽  
Mass Measurements ◽  
Lake System ◽  
Identification Method

The Stikine River in southeastern Alaska supports two principal stocks of sockeye salmon (Oncorhynchus nerka). An expedient means of separating these stocks when they enter freshwater is by egg size and egg mass measurements. Eggs of sockeye that spawn in the Tahltan Lake system are smaller than sockeye spawning elsewhere in the Stikine drainage, a difference supported by an independent stock identification method (scale pattern analysis). Tahltan females have only slightly developed ovaries (1–3% of body weight) and small eggs (2.0–3.5 mm) when they enter freshwater; they enter the river earlier (2–3 wk) and travel farther upstream to spawn than non-Tahltan sockeye. The latter group has more developed ovaries (5–16% of body weight) and larger eggs (3.5–6.2 mm) when they enter the river. Thus, an assessment of egg sizes of sockeye caught in the river can provide on-site information about stock composition and run timing. These data and escapement counts at Tahltan Lake indicate that the total escapement to the Stikine in 1983 was 61 000 to 71 000 sockeye of which 45–53% were Tahltan stock and 47–55% spawned eleswhere in the drainage.

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