scholarly journals Managing Atlantic salmon (Salmo salar L.) in the mixed stock environment: challenges and considerations

2004 ◽  
Vol 61 (8) ◽  
pp. 1344-1358 ◽  
Author(s):  
W.W. Crozier ◽  
P-J. Schön ◽  
G. Chaput ◽  
E.C.E. Potter ◽  
N.Ó Maoiléidigh ◽  
...  
Keyword(s):  
Population Structure ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar ◽  
Mixed Stock ◽  
Made In

Abstract Atlantic salmon, as a result of their population structure and behaviour, are potentially subject to a complex array of fisheries, ranging from those within rivers harvesting single stocks, to distant-water mixed stock fisheries that harvest fish from different countries, stock complexes, and continents. In addition, estuarine and in-river fisheries may catch fish from more than one stock or stock component, where these are present. One of the main challenges in managing salmon across this range of fisheries is to account for the differing status of stocks with respect to safe biological limits, noting that stocks of differing productivity may require different harvest strategies. Also, the existence of sequential harvest in different fisheries provides unique challenges, because decisions in an individual fishery cannot be made in isolation of the impacts of other fisheries on those stocks. We illustrate the uncertainties and complexities involved in managing mixed stocks of salmon, whether in home-waters or in distant-water fisheries, and examples are given to illustrate how science and management are, or should be, developing to face these challenges.

A temporal perspective on population structure and gene flow in Atlantic salmon (Salmo salar) in Newfoundland, Canada

2010 ◽  
Vol 67 (2) ◽  
pp. 225-242 ◽  
Author(s):  
Friso P. Palstra ◽  
Daniel E. Ruzzante
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Gene Flow ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Environmental Changes ◽  
Population Connectivity ◽  
Temporal Perspective ◽  
Atlantic Salmon Salmo Salar ◽  
Contemporary Gene Flow

Studying population structure and gene flow patterns on temporal scales facilitates an evaluation of the consequences of demographic, physical, and environmental changes on the stability and persistence of populations. Here, we examine temporal genetic variation within and among Atlantic salmon ( Salmo salar ) rivers in Newfoundland and Labrador, Canada, using samples collected over a period of six decades (1951–2004). Our objective was to evaluate temporal changes in population connectivity associated with the closure of a commercial marine fishery. Despite demographic instability, we find that population structure remained temporally stable over more than 50 years. However, age structure can affect results when not taken into consideration, particularly in populations of large effective size where genetic drift is not strong. Where weak signals of genetic differentiation did not complicate analyses, contemporary migration was often asymmetric, yet low, suggesting patterns of intermittent gene flow. Nevertheless, we find some links between changes in population dynamics and contemporary gene flow. These findings may therefore imply that management decisions impacting the contemporary population dynamics of individual Atlantic salmon rivers can also affect the genetic stability of this species as a whole.

Atlantic Salmon (Salmo salar) Stocks and Management Implications in the Canadian Atlantic Provinces and New England, USA

1981 ◽  
Vol 38 (12) ◽  
pp. 1612-1625 ◽  
Author(s):  
Richard L. Saunders
Keyword(s):  
Atlantic Salmon ◽  
New England ◽  
Salmo Salar ◽  
Environmental Influence ◽  
Function Analysis ◽  
Significant Degree ◽  
Growth Patterns ◽  
Point Of View ◽  
Atlantic Salmon Salmo Salar ◽  
Mixed Stock

This paper discusses the diversity of Atlantic salmon (Salmo salar) expressed as anatomical, physiological, and behavioral differences among stocks in the Atlantic Provinces of Canada and New England, USA. Evidence is reviewed for environmental and genetic influence on a number of stock-specific traits. Unique qualities of particular stocks are described. The loss of salmon from much of its former range is documented and discussed in relation to stock characteristics important in rehabilitation efforts. The mixed stock fisheries in Greenland and Newfoundland are considered from the point of view of interception. It is concluded that identification and management of specific stocks in the Greenland fishery are impracticable at present but that identification of North American components, using discriminant function analysis of scale growth patterns and smolt tagging, should be continued. In Newfoundland knowledge gained from tagging studies allows a significant degree of management of stocks from mainland Canada together with those from Newfoundland and Labrador. Since it is impracticable now to manage the fisheries off Greenland and Newfoundland and off the major Canadian Maritimes salmon-producing rivers—the Miramichi, Restigouche, and Saint John—in strict recognition of stocks, it is suggested that it may be possible to characterize an assemblage of like stocks from given areas and to identify and manage for these in large mixed-stock fisheries. Possible impacts of hatchery plantings are discussed in relation to prospects of success and effects on native stocks. It is concluded that we have the biological basis for evaluating likelihood of success and degree of danger to native stocks from extensive plantings of hatchery-reared juvenile salmon and that such evaluation should be conducted when embarking on projects involving use of hatchery-reared fish as part of a major salmon enhancement program in Atlantic Canada.Key words: genetics, environmental influence, rehabilitation, enhancement, interception, hatcheries, aquaculture

Temporal Variation of Meristic Traits within an Atlantic Salmon (Salmo salar) Stock, and Implications for Stock Identification

1988 ◽  
Vol 45 (8) ◽  
pp. 1330-1339 ◽  
Author(s):  
D. M. Blouw ◽  
S. D. Saxon ◽  
E. M. P. Chadwick
Keyword(s):  
Atlantic Salmon ◽  
Temporal Variation ◽  
Salmo Salar ◽  
Null Hypothesis ◽  
Temporal Stability ◽  
River System ◽  
Stock Identification ◽  
Atlantic Salmon Salmo Salar ◽  
Group Variation ◽  
Made In

The assumption is generally made in stock identification studies that variation within stocks is not confounded with variation among them. To evaluate whether this assumption is tenable we test the null hypothesis of temporal stability in five key meristic traits of a single stock of Atlantic salmon (Salmo salar). We used smolts collected over a 10-yr period in the downstream migrations from one small river system. Individuals were tagged when captured and preserved, so we can estimate variability within, as well as among, runs. The meristic traits are remarkably homogenous within runs and cohorts. However, the null hypothesis of stability over time among runs and cohorts is strongly rejected for each trait. We conclude that temporal variation is both extensive and persistent. There is limited covariation among the traits, but they are largely independent of scores of environmental variables and of variation in the biological attributes of the stock. Because among-group variability is meaningful only in context of within-group variation, and because the within-group variation is large, our results have serious implications for sampling design in stock identification studies.

scholarly journals Provision of catch advice taking account of non-stationarity in productivity of Atlantic salmon (Salmo salar L.) in the Northwest Atlantic

2005 ◽  
Vol 62 (1) ◽  
pp. 131-143 ◽  
Author(s):  
G. Chaput ◽  
C.M. Legault ◽  
D.G. Reddin ◽  
F. Caron ◽  
P.G. Amiro
Keyword(s):  
Population Dynamics ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Model Prediction ◽  
Northwest Atlantic ◽  
Atlantic Salmon Salmo Salar ◽  
Parsimonious Models ◽  
Rate Of Decline ◽  
Management Advice ◽  
Mixed Stock

Abstract The paper presents the data, the models, and the approach for the provision of management advice for a high seas mixed stock fishery on Atlantic salmon (Salmo salar L.). The approach incorporates observation errors, model uncertainty, and considers a possible shift in the productivity of Atlantic salmon. The risk analysis framework further incorporates uncertainty in the fishery harvest characteristics and presents the catch advice as probabilities of meeting or exceeding the conservation objectives relative to catch options. There is very strong evidence from the analyses that there has been a phase shift in productivity of Atlantic salmon of North American origin in the Northwest Atlantic. The change in productivity likely resulted from a change in marine survival which occurred in the early 1990s and has persisted to date. When the uncertainties in the input data are considered, the most parsimonious models suggest that there has been a shift in absolute abundance independent of variations in the spawner index contributing to the recruitment. There continues to be a large amount of uncertainty in the measures of abundance and population dynamics of Atlantic salmon. Uncertainty in the understanding of population dynamics does not necessarily equate to uncertainty in management advice. If model results suggest that spawning objectives are unattainable even when harvest rates are zero, then any harvest level will either accelerate the rate of decline if the model prediction is correct or diminish the probability of recovery if the model prediction is wrong.

Hotelling's T2 to Identify the Origin of Atlantic Salmon (Salmo salar) in a Mixed-Stock Fishery

1985 ◽  
Vol 42 (2) ◽  
pp. 250-255 ◽  
Author(s):  
D. G. Reddin ◽  
R. K. Misra
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Misclassification Rate ◽  
Commercial Fishery ◽  
Commercial Sample ◽  
New Approach ◽  
Atlantic Salmon Salmo Salar ◽  
Leave One Out ◽  
Mixed Stock ◽  
River Size

We used a new approach based on measurements of four scale characters, for identifying Atlantic salmon (Salmo salar) caught in the commercial fishery at St. Ann's Harbour, Nova Scotia, and that were returning to North River. Utilizing Hotelling's T2, we compared the vector of observations of each member of the commercial sample (size = 29) with the vector of means of the sample from the angling fishery on North River (size = 48). Misclassification rate was estimated by the "leave-one-out" technique. The variables chosen for analysis were the measurements of the longest oral radii between each of the first three river and first sea annuli. The analysis indicated that 79–88% of the individuals in the commercial sample could have been migrating to North River. This technique is proposed for cases in which the requirement to have samples from all contributing stocks for discriminant analysis is not possible.

Spatiotemporal dynamics of the Atlantic salmon (Salmo salar) Greenland fishery inferred from mixed-stock analysis

2009 ◽  
Vol 66 (12) ◽  
pp. 2040-2051 ◽  
Author(s):  
Marika Gauthier-Ouellet ◽  
Mélanie Dionne ◽  
François Caron ◽  
Tim L. King ◽  
Louis Bernatchez
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Time Course ◽  
Fish Stocks ◽  
Atlantic Salmon Salmo Salar ◽  
The North ◽  
Different Origins ◽  
Mixed Stock ◽  
Mortality Estimates

Mixed-stock fisheries refer to the exploitation of admixed fish stocks coming from different origins. We identified the North American origin of 2835 Atlantic salmon ( Salmo salar ) in the Greenland mixed-stock fishery during 11 years (1995–2006) at three localities using 13 microsatellites. The study included 52 baseline populations representing nine genetically distinct regional groups. The contribution of each group ranged from <1% (Maine) to 40% (Southern Québec). Decreasing temporal contributions were observed for Southern Québec (–22.0%) and New Brunswick (–17.4%), whereas an increasing contribution for Labrador (+14.9%) was observed during the time course of the study. The estimated regional contribution to the Greenland fishery was significantly correlated to the number of multi-sea-winter salmon regionally produced in 2002 (r = 0.79) and 2004 (r = 0.92). No difference in contribution was found between the three Greenland sampling localities. Ungava and Southern Québec regions showed the highest mortality estimates caused by the fishery, ranging from 12.10% to 18.08%, for both years tested. No regional group was overrepresented in landings compared with their respective productivity. Yet, management precautions should still be taken as the fishery strongly selects large females, which could have evolutionary impacts on populations over the long term.

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