Effect of maturation on parr growth and smolt recruitment of Atlantic salmon

1999 ◽  
Vol 56 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Kevin G Whalen ◽  
Donna L Parrish

We determined the effect of maturation on parr growth and smolt recruitment of Atlantic salmon (Salmo salar) stocked in Vermont tributaries of the Connecticut River. Both among and within tributaries, mature parr ranged between 28 and 52% of the age-1 parr collected and up to 67% of the age-2 parr collected. Percent age-1 parr maturing in October-November was positively related to mean length the preceding June. In October-November, immature age-1 parr were greater in mean length than age-1 mature parr. Data from parr individually tagged in June and recaptured in October showed immature parr exhibited twofold greater individual growth than maturing parr. Smolt recruitment was highly dependent upon state of maturity the preceding fall; fewer individuals that matured as parr recruited to smolt compared with parr remaining immature. Our study shows, over a broad spatial scale, that variation in incidence of maturation is largely explained by parr size among tributaries and river reaches and, furthermore, empirically demonstrates a direct negative effect of maturation on parr growth and recruitment to smolt. Thus, parr maturation is an important consideration for the enhancement and (or) restoration of Atlantic salmon populations via stream stocking programs.

2004 ◽  
Vol 61 (12) ◽  
pp. 2392-2400 ◽  
Author(s):  
Francis Juanes ◽  
Stephen Gephard ◽  
Kenneth F Beland

The Connecticut River historically represented the southernmost extent of the North American range of Atlantic salmon (Salmo salar), but the native population was extirpated 200 years ago by dam construction. An extensive restoration effort has relied upon stock transfers from more northerly rivers, especially the Penobscot River (Maine). Recent work has shown differences in age structure between donor and derivative populations. Here we focus on a related life-history trait, the timing of the adult migration. We examined 23 years of migration timing data collected at two capture locations in the Connecticut River drainage. We found that both dates of first capture and median capture dates have shifted significantly earlier by about 0.5 days·year–1. To conclude whether this is a consequence of local adaptation or a coast-wide effect, we also quantified changes in migration timing of more northerly stocks (in Maine and Canada). We found that the changes in migration timing were not unique to the Connecticut River stock and instead observed coherent patterns in the shift towards earlier peak migration dates across systems. These consistent shifts are correlated with long-term changes in temperature and flow and may represent a response to global climate change.


2003 ◽  
Vol 60 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Matthew J Raffenberg ◽  
Donna L Parrish

Competitive interactions among stream salmonids in resource-limited environments have been linked to reduced success for many species. Few studies have focused on interactions at scales larger than individual fish or stream reach. We chose to focus our study on these larger scales to provide information for managing species that have complex life histories transcending multiple scales. Our objective was to explore age-0 Atlantic salmon (Salmo salar) growth and survival in relation to trout abundance (introduced rainbow (Oncorhynchus mykiss) and native brook (Salvelinus fontinalis) trout) and prey resources at 24 stream reaches across two Vermont watersheds that flow into the Connecticut River. Simple linear and multilinear regressions were conducted on response and predictor variables related to fish and invertebrate prey. Age-0 Atlantic salmon survival was greatest at the site with highest trout abundance; however, no linear relationships to trout abundance were detected possibly because Atlantic salmon growth and survival were highly variable across sites. In contrast, a positive significant multivariate relationship was identified among age-0 Atlantic salmon survival, the abundance of age-1+ brook trout (i.e., 100–130 mm), and benthic prey abundance. These results suggest that stocking streams based on trout abundance may not increase Atlantic salmon growth and survival during the first summer of life.


2009 ◽  
Vol 66 (5) ◽  
pp. 865-870 ◽  
Author(s):  
Rocco C. Cipriano

AbstractCipriano, R. C. 2009. Antibody against infectious salmon anaemia virus among feral Atlantic salmon (Salmo salar). – ICES Journal of Marine Science, 66: 865–870. Archived sera from Atlantic salmon (Salmo salar) that returned to the Penobscot River (Maine), Merrimack River (Massachusetts), and Connecticut River (in Massachusetts) from 1995 to 2002 were analysed for antibodies against infectious salmon anaemia virus (ISAV) using an enzyme-linked immunosorbent assay (ELISA). Up to 60 samples were archived per river system per year. In a given year, the number of fish sampled by ELISA for ISAV antibodies in the Penobscot River ranged from 2.9 to 11.2%, and the range of salmon sampled in the Merrimack River and the Connecticut River was 31.3–100% and 20.0–67.5%, respectively. Archived sera were not available for the 1995 and 2002 year classes from the Connecticut River. In all, 1141 samples were processed; 14 serum samples tested positive for antibodies to ISAV. In the Penobscot River, serum from one fish tested positive in each of the 1995 and 1999 year-class returns, and sera from two fish tested positive in the 1998 returns. In the Merrimack River, sera from four fish tested positive in each of the 1996 and 1997 returns, and sera from two fish were positive in the 2002 return. None of the archived sera from Atlantic salmon that returned to the Connecticut River tested positive.


2000 ◽  
Vol 57 (8) ◽  
pp. 1607-1616 ◽  
Author(s):  
Kevin G Whalen ◽  
Donna L Parrish ◽  
Martha E Mather ◽  
James R McMenemy

We used estimates of Atlantic salmon (Salmo salar) parr and smolt density, estimated in three tributaries of the West River, Vermont, U.S.A., to determine (i) if smolt recruitment is density dependent or independent of parr density, (ii) if the proportion of parr migrating as smolts and cohort survival differ among tributaries, and (iii) the effect of parr maturity on smolt production and recruitment variability. We found that parr to smolt recruitment was best described with a linear function providing no evidence for density dependence in the recruitment dynamics of parr and smolts at the tributary scale. The proportion of age-1 parr recruiting to age-2 smolts did not systematically differ among tributaries or years (overall mean ± 95% CL: 18 ± 11%, range = 9-37%), and mean age-1 to age-2 survival ranged less than twofold among tributaries (27-46%) and was independent of cohort density. Survival of age-1 mature (39%) and immature (33%) parr was similar, but probability of smolting for mature parr (0.21) was threefold less than for immature parr (0.76). Quantifying smolt recruitment pathways involving parr maturation helped elucidate the population-level effect of parr maturation on smolt production and recruitment variability.


2005 ◽  
Vol 62 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Brian P Kennedy ◽  
C Page Chamberlain ◽  
Joel D Blum ◽  
Keith H Nislow ◽  
Carol L Folt

We compared the success of using naturally occurring stable isotopes of N, C, and Sr as markers for the rearing locations of juvenile salmon. We analyzed the isotopic signatures (δ15N and δ13C in muscle and scales and 87Sr/86Sr in otoliths) of >200 juvenile Atlantic salmon (Salmo salar) from 12 tributaries of the Connecticut River, USA. Young salmon had distinct N and C signatures 5 weeks after stocking. Signatures were stable over the summer although δ13C varied more than δ15N or 87Sr/86Sr. Scale and muscle signatures were highly correlated, demonstrating the feasibility of nonlethal sampling using fish scales. Some C (but not N) signature from the hatchery was retained in scales of 3-month-old fish, implicating scale annuli as a repository for past C signatures. The δ15N values successfully differentiated fish from tributaries with differences in land use (e.g., agricultural versus forested; ≈ 33% of sites); the δ13C values differentiated fish from 45% of sites. Based upon a discriminant-function analysis, group membership of individuals was correctly predicted in 44.3% (74 of 167) of cases for which both N and C were analyzed. In combination, N and C isotopes differentiated 73% of study sites, which was close to the success of Sr isotopes in the same system (83%).


2001 ◽  
Vol 58 (9) ◽  
pp. 1812-1821 ◽  
Author(s):  
Benjamin H Letcher ◽  
Tim L King

Large-scale use of parentage assignment of stocked Connecticut River, U.S.A., Atlantic salmon (Salmo salar) fry to determine stocking tributary of emigrating smolts and returning adults requires both parentage assignment and grandparentage assignment. Using computer simulations, we explored the levels of genetic diversity necessary to provide adequate parentage and grandparentage assignment. When matings were known, as in a hatchery, 95% correct grandparentage assignment typically required at least twofold more alleles per locus than did 95% correct parentage assignment. Parentage assignment with unknown matings (as in the wild when parental genotypes can be assayed) required an intermediate number of alleles per locus and grandparentage assignment with unknown matings required the greatest genetic diversity. Computer simulations using empirical parental genotypes (14 loci) and known P1 matings indicated that the genetic diversity of Connecticut River Atlantic salmon broodstock is sufficient to assign all F1 and 97% of F2 offspring to the correct set of two parents or four grandparents, respectively. Grandparentage assignment with unknown P1 matings was ineffective (assignment success = 20%). These results indicate that the combination of parentage and grandparentage assignment can be used as a non-lethal, permanent, heritable "mark" to identify stocking tributary or other management directed characteristics of stocked fry.


2003 ◽  
Vol 60 (5) ◽  
pp. 506-516 ◽  
Author(s):  
Nina Jonsson ◽  
Bror Jonsson

Relationships between energy density (kJ·100 g–1) and body length (mm), which varied between life-history stages of Atlantic salmon (Salmo salar), were described by power functions. The variation was chiefly caused by differences in lipid concentrations. Energy densities of maturing and rematuring parr were higher than those of similarly aged smolts. Monthly specific growth rate was higher in maturing parr than in salmon at sea. Mature parr males allocated relatively more energy to gonadal development and less to soma development than anadromous males. Spawning expenditure increased from 34 to 53% for 55- to 72-cm-long females. In males, similar losses were from 47 to 49% of their total energy content at river entry. More energy was used in reproduction in a long river than in a short one. Male allocation to gonads relative to soma was highest in the shorter river. Energy allocation pattern varied among developmental stages. Very energy-rich male parr rematured in subsequent years without going to sea; less energy-rich ones smolted and migrated to sea.


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