scholarly journals Retrospective analysis of marine growth and relationships to return rates of Penobscot River Atlantic salmon

2021 ◽  
Author(s):  
Miguel Fillion Barajas ◽  
Timothy F Sheehan ◽  
Ruth Haas-Castro ◽  
Brandon Ellingson ◽  
Katherine Mills
Keyword(s):  
Atlantic Salmon ◽  
North American ◽  
Principal Component ◽  
Growth Increment ◽  
Growth Time ◽  
Seasonal Growth ◽  
Return Rates ◽  
Growth Increments ◽  
Penobscot River ◽  
Marine Survival

Beginning in the 1980s, return rates of Atlantic salmon to the Penobscot River, Maine U.S.A. declined and have persisted at low levels. This downturn coincided with similar declines in North American and European Atlantic salmon stocks and with changes in the Northwest Atlantic ecosystem. Previous studies investigated whether early marine growth explained the declines, but results varied, with decreased growth associated with declines in European stocks but not North American stocks. In this study, we evaluate whether growth over the entire marine stage is related to Atlantic salmon marine survival. We constructed a growth time series from scales of returned Penobscot River Atlantic salmon spanning periods of varying marine survival. We used ANOVA and post-hoc tests to quantify seasonal growth increment differences and principal component analysis to characterize variability among the suite of growth increments. We observed reduced growth during the second winter and second marine year starting in the 1990s, with compensatory seasonal growth relationships. These results indicate that diminished growth during late marine stages is associated with low return rates in this population.

Seasonal growth pattern in the lichen Pseudocyphellaria berberina in north-western Patagonia

2004 ◽  
Vol 36 (6) ◽  
pp. 435-444 ◽  
Author(s):  
Mayra S. CALDIZ
Keyword(s):  
Growth Increment ◽  
Annual Growth ◽  
Seasonal Growth ◽  
Epiphytic Lichen ◽  
Growth Increments ◽  
The Mean ◽  
Individual Trees ◽  
Nothofagus Dombeyi ◽  
North Western ◽  
Annual Growth Increment

Seasonal growth increments (%) were measured in the foliose epiphytic lichen Pseudocyphellaria berberina in north-western Patagonia. Growth was determined by measuring increase in weight (expressed as percentage of the original biomass) in transplanted thalli. Transplants were either hung freely from wooden frames or attached to tree trunks in a Nothofagus dombeyi forest and then weighed every three months between January 2001 and April 2003. The influence on growth increment of treatment, donor thallus, temperature, and absolute and relative humidity was analysed. Mean annual growth increment after two years, in both treatments was 12±1·07% (±SE). Growth increment was greatest in winter and lowest in summer; the mean winter growth increment was 6±0·50%, representing half of the annual growth, whereas most of the remaining growth occurred during both spring and autumn. Growth increments were similar for freely-hanging lichens and for the transplants attached to tree trunks. Individual trees had no consistent effect on growth while the donor thallus had a significant effect in the first season which then diminished, indicating acclimation in the transplants. Initial transplant weight had no influence on final cumulative growth, nor was there any consistent correlation between one season and another in the growth of transplants. Both transplantation methods proved to be useful for experiments on the growth of P. berberina.

scholarly journals Embedding stock assessment within an integrated hierarchical Bayesian life cycle modelling framework: an application to Atlantic salmon in the Northeast Atlantic

2014 ◽  
Vol 71 (7) ◽  
pp. 1653-1670 ◽  
Author(s):  
Félix Massiot-Granier ◽  
Etienne Prévost ◽  
Gérald Chaput ◽  
Ted Potter ◽  
Gordon Smith ◽  
...  
Keyword(s):  
Life Cycle ◽  
Atlantic Salmon ◽  
Density Dependence ◽  
Temporal Dynamics ◽  
Stock Assessment ◽  
Assessment Method ◽  
Hierarchical Bayesian ◽  
Return Rates ◽  
Modelling Framework ◽  
Marine Survival

Abstract We developed a hierarchical Bayesian integrated life cycle model for Atlantic salmon that improves on the stock assessment approach currently used by ICES and provides some interesting insights about the population dynamics of a stock assemblage. The model is applied to the salmon stocks in eastern Scotland. It assimilates a 40-year (1971–2010) time-series of data compiled by ICES, including the catches in the distant water fisheries at Faroes and West Greenland and estimates of returning fish abundance. Our model offers major improvements in terms of statistical methodology for A. salmon stock assessment. Uncertainty about inferences is readily quantified in the form of Bayesian posterior distributions for parameters and abundance at all life stages, and the model could be adapted to provide projections based on the uncertainty derived from the estimation phase. The approach offers flexibility to improve the ecological realism of the model. It allows the introduction of density dependence in the egg-to-smolt transition, which is not considered in the current ICES assessment method. The results show that this modifies the inferences on the temporal dynamics of the post-smolt marine survival. In particular, the overall decrease in the marine survival between 1971 and 2010 and the sharp decline around 1988–1990 are dampened when density dependence is considered. The return rates of smolts as two-sea-winter (2SW) fish has declined in a higher proportion than return rates as one-sea-winter (1SW) fish. Our results indicate that this can be explained either by an increase in the proportion maturing as 1SW fish or by an increase in the mortality rate at sea of 2SW fish, but the data used in our analyses do not allow the likelihood of these two hypotheses to be gauged.

scholarly journals Atlantic salmon return rate increases with smolt length

2019 ◽  
Vol 76 (6) ◽  
pp. 1702-1712 ◽  
Author(s):  
Stephen D Gregory ◽  
Anton T Ibbotson ◽  
William D Riley ◽  
Marie Nevoux ◽  
Rasmus B Lauridsen ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Salmon ◽  
Survival Rates ◽  
Empirical Support ◽  
Return Rate ◽  
Imperfect Detection ◽  
Factors Affecting ◽  
Return Rates ◽  
Life Phase ◽  
Marine Survival

Abstract Recent declines in Atlantic salmon Salmo salar populations are generally attributed to factors in their marine life-phase. However, it is postulated that factors affecting their freshwater life-phase might impact their marine survival, such as the influence of body size. While larger smolts are widely hypothesized to have higher marine survival rates, empirical support remains scant, in part due to inadequate data and ambiguous statistical analyses. Here, we test the influence of smolt body size on marine return rates, a proxy for marine survival, using a 12-year dataset of 3688 smolts tagged with passive integrated transponders in the River Frome, Southern England. State-space models describe the probability of smolts surviving their marine phase to return as 1 sea-winter (1SW) or multi-sea-winter adults as a function of their length, while accounting for imperfect detection and missing data. Models predicted that larger smolts had higher return rates; the most parsimonious model included the effect of length on 1SW return rate. This prediction is concerning, as freshwater juvenile salmon are decreasing in size on the River Frome, and elsewhere. Thus, to maximize adult returns, restoration efforts should focus on freshwater life-stages, and maximize both the number and the size of emigrating smolts.

scholarly journals Genetic mixed-stock analysis disentangles spatial and temporal variation in composition of the West Greenland Atlantic Salmon fishery

2016 ◽  
Vol 73 (9) ◽  
pp. 2311-2321 ◽  
Author(s):  
Ian R. Bradbury ◽  
Lorraine C. Hamilton ◽  
Timothy F. Sheehan ◽  
Gerald Chaput ◽  
Martha J. Robertson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
North American ◽  
Temporal Stability ◽  
Spatial And Temporal Variation ◽  
Published Data ◽  
The West ◽  
West Greenland ◽  
Archived Samples ◽  
Mixed Stock ◽  
Salmon Fishery

Abstract The West Greenland Atlantic Salmon (Salmo salar) fishery represents the largest remaining mixed-stock fishery for Atlantic Salmon in the Northwest Atlantic and targets multi-sea-winter (MSW) salmon from throughout North America and Europe. We evaluated stock composition of salmon harvested in the waters off West Greenland (n = 5684 individuals) using genetic mixture analysis and individual assignment to inform conservation of North American populations, many of which are failing to meet management targets. Regional contributions to this fishery were estimated using 2169 individuals sampled throughout the fishery between 2011 and 2014. Of these, 22% were identified as European in origin. Major North American contributions were detected from Labrador (∼20%), the Southern Gulf/Cape Breton (29%), and the Gaspe Peninsula (29%). Minor contributions (∼5%) were detected from Newfoundland, Ungava, and Quebec regions. Region-specific catches were extrapolated using estimates of composition and fishery catch logs and harvests ranged from 300 to 600 and 2000 to 3000 individuals for minor and major constituents, respectively. To evaluate the temporal stability of the observed fishery composition, we extended the temporal coverage through the inclusion of previously published data (1995–2006, n = 3095) and data from archived scales (1968–1998, n = 420). Examination of the complete time-series (47 years) suggests relative stability in stock proportions since the late 1980s. Genetic estimates of stock composition were significantly associated with model-based estimates of returning MSW salmon (individual years r = 0.69, and overall mean r = 0.96). This work demonstrates that the analysis of both contemporary and archived samples in a mixed-stock context can disentangle levels of regional exploitation and directly inform assessment and conservation of Atlantic Salmon in the West Greenland interceptory Atlantic Salmon fishery.

Description and Quantification of Sexual Dimorphism of Pubic Body Shape in Hispanic Populations Using Elliptic Fourier Analysis

2021 ◽  
Author(s):  
Erica Cantor ◽  
Krista Latham ◽  
Stephen Nawrocki
Keyword(s):  
Fourier Analysis ◽  
North American ◽  
Principal Component ◽  
Pubic Bone ◽  
Biological Traits ◽  
Sex Estimation ◽  
Age At Death ◽  
Elliptic Fourier Analysis ◽  
Hispanic Populations ◽  
Effective Principal

Sex estimation is important in the creation of a biological profile for unidentified human remains, as positive identification cannot occur until the decedent’s biological traits have been determined and the range of possible matches has been narrowed. The pubic bone is cited as one of the best indicators of sex due to the constraints of childbirth. Current methods that use the pubic bone for sex estimation, however, rely on poorly defined and subjective observations that are susceptible to inter-and intraobserver error. Additionally, many of the methods currently in use are based on North American populations and thus may not necessarily model the variation seen in other populations around the globe. The aim of this study is to gain a better understanding of variation in pubic bone shape in Hispanic populations by separating the influences of sex, ancestry, and age at death. A total of 164 pubic bones from North American Hispanic and Chilean individuals were compared to 287 pubic bones from individuals of Euro-American ancestry from North American collections, using Elliptic Fourier analysis (EFA) of photographs, principal component analysis, and ANCOVA. EFA generated five effective principal components that collectively describe approximately 95% of the variation in the shape of the pubic body. Sex, age at death, and ancestry were all found to significantly influence shape but explained only 25% of the overall variation. The remaining 75% is likely influenced by variables that cannot be controlled for in anthropological analysis, underscoring how little variance in skeletal morphology is actually explainable.

scholarly journals Assessing demographic effects of dams on diadromous fish: a case study for Atlantic salmon in the Penobscot River, Maine

2015 ◽  
Vol 72 (8) ◽  
pp. 2423-2437 ◽  
Author(s):  
Julie L. Nieland ◽  
Timothy F. Sheehan ◽  
Rory Saunders
Keyword(s):  
Atlantic Salmon ◽  
Performance Metrics ◽  
Survival Rates ◽  
Population Viability Analysis ◽  
River System ◽  
Diadromous Fish ◽  
Viability Analysis ◽  
Penobscot River ◽  
Passage Efficiency ◽  
Demographic Effects

Abstract Dams are a major contributor to the historic decline and current low abundance of diadromous fish. We developed a population viability analysis to assess demographic effects of dams on diadromous fish within a river system and demonstrated an application of the model with Atlantic salmon in the Penobscot River, Maine. We used abundance and distribution of wild- and hatchery-origin adult salmon throughout the watershed as performance metrics. Salmon abundance, distribution to upper reaches of the Penobscot watershed, and the number and proportion of wild-origin fish in the upper reaches of the Penobscot watershed increased when dams, particularly mainstem dams, were removed or passage efficiency was increased. Salmon abundance decreased as indirect latent mortality per dam was increased. Salmon abundance increased as marine or freshwater survival rates were increased, but the increase in abundance was larger when marine survival was increased than when freshwater survival was increased. Without hatchery supplementation, salmon abundance equalled zero with low marine and freshwater survival but increased when marine and freshwater survival rates were increased. Models, such as this one, that incorporate biological, environmental, and functional parameters can be used to predict ecological responses of fish populations and can help evaluate and prioritize management and restoration actions for diadromous fish.

Otolith and fish size relationships, measurement error, and size-selective mortality during the early life of Atlantic salmon (Salmo salar)

1998 ◽  
Vol 55 (7) ◽  
pp. 1663-1673 ◽  
Author(s):  
M G Meekan ◽  
J J Dodson ◽  
S P Good ◽  
DAJ Ryan
Keyword(s):  
Measurement Error ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Data Sets ◽  
Regression Analyses ◽  
Fish Size ◽  
Atlantic Salmon Salmo Salar ◽  
Weak Relationship ◽  
Growth Increments ◽  
Otolith Size

The development of the relationship between otolith and body size in Atlantic salmon (Salmo salar) between hatching and emergence was examined by repeatedly measuring individually identified fish. Otolith growth increments were deposited daily in the period between hatching and emergence. Comparison of back-calculated otolith size and standard length using least squares regression analyses revealed a weak relationship between these variables at each of the 5-day sampling intervals. However, when data sets were pooled among intervals, variation in otolith size accounted for 98% of the variation in alevin length. A computer simulation demonstrated that levels of measurement error similar to those documented in our study resulted in the failure of regression analyses to detect strong relationships between otolith and fish size. Mortality that occurred during the experiment was strongly size selective. This truncated the size ranges of fish in cross-sectional data sets and thus reduced the ability of regression analysis to detect relationships between otolith and fish size. We propose that the weak relationship between otolith and fish size at emergence recorded in previous studies was an artifact of measurement error and the truncation of size ranges in regression analyses. Differences in alevin size at emergence were present at hatching and had been propagated by growth.

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