Escapement goal analysis and stock reconstruction of sockeye salmon populations (Oncorhynchus nerka) using life-history models

2008 ◽  
Vol 65 (10) ◽  
pp. 2269-2278 ◽  
Author(s):  
Robert B. Lessard ◽  
Ray Hilborn ◽  
Brandon E. Chasco
Keyword(s):  
Life History ◽  
Sockeye Salmon ◽  
Model Estimate ◽  
Policy Variable ◽  
Optimal Harvest ◽  
Spawning Stock ◽  
Maximum Sustained Yield ◽  
History Of ◽  
Stock Recruitment

We compare life-history models with the Beverton–Holt approach of escapement goal analysis. We model the life history of a sockeye salmon ( Onchorhynchus nerka ) population from a spawning stage, through juvenile and adult stages, and ending with adults that return to spawn. We fit models to data by statistically comparing predicted and observed numbers of four dominant adult ages. Posterior estimates of parameters from Markov chain Monte Carlo simulations are then used to assess optimal harvest policies. We search for policies that produce the highest average yield. We find that it is possible to detect density dependence with a life-history model where analysis of Beverton–Holt stock–recruitment relationship fails to do so. We find that Beverton–Holt relationships produce policies and long-term yield estimates that are inconsistent with empirical trends. Conversely, we find that optimal spawning stock sizes and maximum sustained yield estimates using the life-history model estimate are consistent with the historical behavior of fisheries examined. Adding smolt data to the analysis does not substantially change predicted optimal spawning stock size, but decreases the variance in estimated posterior parameter distributions and policy variable distributions.

Kokanee–sockeye salmon hybridization leads to intermediate morphology and resident life history: implications for fisheries management

2020 ◽  
Vol 77 (2) ◽  
pp. 355-364
Author(s):  
Lucas D. Elliott ◽  
Hillary G.M. Ward ◽  
Michael A. Russello
Keyword(s):  
Life History ◽  
Sockeye Salmon ◽  
Management Strategies ◽  
Empirical Support ◽  
Intermediate Morphology ◽  
Intermediate Size ◽  
Freshwater Resident ◽  
Historical Range ◽  
Hybridization And Introgression

Stocking programs designed to return extirpated species to their historical range have become increasingly prevalent, punctuating the need to better understand the risks posed to recipient ecosystems. Here, we investigated the genetic and biological consequences of an anadromous sockeye salmon (Oncorhynchus nerka) stocking program in Skaha Lake, British Columbia, where substantial levels of hybridization and introgression with the native freshwater resident ecotype (kokanee) have been detected. We genetically assigned 543 individuals (adult spawners, age-0 juveniles) to estimate stock proportions (pure-stock sockeye, pure-stock kokanee, or hybrid) between 2010 and 2017, with a subset undergoing otolith microchemistry analysis to determine migratory life history and maternal ancestry. The proportion of hybrid spawners varied from 5% to 20% across sampling years, while that of hybrid age-0 juveniles remained relatively constant (∼11%). Hybrid spawners exhibited intermediate size relative to pure stocks, with the vast majority being nonanadromous (92%) and of resident maternal ancestry (76%). Our results provide empirical support for previously hypothesized mechanisms of hybridization between O. nerka life-history forms and underscore the importance of continued monitoring of stocking programs to quantify long-term fitness impacts of introgression and refine management strategies.

Early Ocean Life History of Harrison River Sockeye Salmon and their Contribution to the Biodiversity of Sockeye Salmon in the Fraser River, British Columbia, Canada

2016 ◽  
Vol 145 (2) ◽  
pp. 348-362 ◽  
Author(s):  
Richard J. Beamish ◽  
Chrys M. Neville ◽  
Ruston M. Sweeting ◽  
Terry D. Beacham ◽  
Joy Wade ◽  
...  
Keyword(s):  
British Columbia ◽  
Life History ◽  
Sockeye Salmon ◽  
Fraser River ◽  
History Of

Long-term monitoring of the life history of a riverine mayfly Ephemera orientalis (Ephemeroptera: Ephemeridae) in the Han River in Seoul, Korea

2011 ◽  
Vol 41 (6) ◽  
pp. 287-287 ◽  
Author(s):  
Cha Young Lee ◽  
Jeong Mi Hwang ◽  
Tae Joong Yoon ◽  
Dong Gun Kim ◽  
Min Jeong Beak ◽  
...  
Keyword(s):  
Life History ◽  
Han River ◽  
History Of ◽  
Long Term Monitoring ◽  
Term Monitoring

scholarly journals Memory and Alterity in Zar: Religious Contact and Change in the Sudan

2019 ◽  
Vol 8 ◽  
Author(s):  
Susan M Kenyon
Keyword(s):  
Life History ◽  
The Other ◽  
Ethnographic Research ◽  
The Past ◽  
Life History Data ◽  
History Of ◽  
The One ◽  
Ninteenth Century ◽  
Dynamic Interplay

Drawing on long-term ethnographic research in the Blue Nile town of Sennar, supported by archival and historical documentation, this article explores the history of Zar spirit possession in Sudan, and the light this throws on the interplay of religions over the past 150 years. Life history data supports the argument that contemporary Zar is grounded in forms and rituals derived from the ranks of the ninteenth-century Ottoman army, and these remain the basis of ritual events, even as they accommodate ongoing changes in this part of Africa. Many of these changes are linked to the dynamic interplay of Zar with forms of Islam, on the one hand, and Christianity, on the other. In the former colonial periods, political power resided with the British, and Khawaja (European) Christian Zar spirits are remembered as far more important. Today that authority in Zar has shifted to spirits of foreign Muslims and local holy men, on the one hand, and to subaltern Blacks, on the other. These speak to concerns of new generations of adepts even as changes in the larger political and religious landscapes continue to transform the context of Zar.

Improving the stock-recruitment relationship in Icelandic cod (Gadus morhua) by including age diversity of spawners

1998 ◽  
Vol 55 (6) ◽  
pp. 1372-1377 ◽  
Author(s):  
Gudrun Marteinsdottir ◽  
Kristjan Thorarinsson
Keyword(s):  
Gadus Morhua ◽  
Extended Period ◽  
Shannon Index ◽  
Age Composition ◽  
Stock Size ◽  
Age Diversity ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Mature Fish

The size of the Icelandic cod stock has been gradually declining since the middle of this century. Recruitment has been poor over an extended period of time and much below the long-term average since 1985. Except for the concurrent decrease in stock size and recruitment during this period, the stock size - recruitment relationship is weak. This relationship is improved by including the age composition of the spawning stock. Spawning stock age diversity in each year from 1955 to 1992 was estimated with the Shannon index using the number of mature fish in each age group. By including information on age composition, 31% of the total variation in recruitment was accounted for by the model with stock size, age diversity, and the interaction between the two, compared with less than 15% by single factor models of either age diversity or stock size. These results indicate that age diversity is an important component in stock-recruitment models and that one of the management goals for fish species should be to maintain high age diversity in the spawning stocks.

Benthic Life Histories: Summary and Future Needs

1979 ◽  
Vol 36 (3) ◽  
pp. 342-345 ◽  
Author(s):  
T. F. Waters
Keyword(s):  
Life History ◽  
Physical Environment ◽  
Life Histories ◽  
Future Research ◽  
Life History Stages ◽  
History Information ◽  
History Of ◽  
Taxonomic Methods ◽  
Key Words Life History

The symposium indicated many ways in which greater knowledge of benthic life histories can be used to develop and improve techniques such as sampling, taxonomic methods, and bioassays. Benthic organisms' diet and physical environment, factors variable in nature, were shown to be capable of modifying certain life history features such as growth rate and voltinism. The lack of accumulated life history data and the need to tailor sampling schedules to life history events were commonly identified elements in the symposium. Future research needs included (1) basic data on benthic life history, (2) improved taxonomy of immature benthic invertebrates, and (3) understanding the entire life history of an organism in relation to the seasonal progression of its environment. Management implications of benthic life history information included more applicable data from long-term bioassays on all life history stages, and improved management of stream fisheries through habitat alteration to manipulate benthic production. Key words: life history, benthos, symposium

scholarly journals LTP after Stress: Up or Down?

2007 ◽  
Vol 2007 ◽  
pp. 1-6 ◽  
Author(s):  
Marian Joëls ◽  
Harm J. Krugers
Keyword(s):  
Life History ◽  
Long Term Potentiation ◽  
Memory Formation ◽  
Stressful Situation ◽  
Behavioral Performance ◽  
The Past ◽  
Term Potentiation ◽  
History Of ◽  
The Brain

When an organism is exposed to a stressful situation, corticosteroid levels in the brain rise. This rise has consequences for behavioral performance, including memory formation. Over the past decades, it has become clear that a rise in corticosteroid level is also accompanied by a reduction in hippocampal long-term potentiation (LTP). Recent studies, however, indicate that stress does not lead to a universal suppression of LTP. Many factors, including the type of stress, the phase of the stress response, the area of investigation, type of LTP, and the life history of the organism determine in which direction LTP will be changed.

Aspects of spawner-recruit relationships, with particular reference to crustacean stocks: A review

1993 ◽  
Vol 44 (4) ◽  
pp. 589 ◽  
Author(s):  
N Caputi
Keyword(s):  
Fisheries Management ◽  
Environmental Variables ◽  
Short Term ◽  
Stochastic Variation ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
The Impact ◽  
Western Australian ◽  
Crustacean Fisheries

The fundamental biological issue for fisheries management is undoubtedly the prevention of recruitment overfishing, i.e. to prevent the spawning stock from being depleted by fishing to a level where it significantly reduces the abundance of recruits. However, for many important fisheries, particularly crustacean fisheries, the stock-recruitment relationship (SRR) is not known. In many cases, research on recruitment has concentrated on short-term studies of recruitment processes to the exclusion of research into the SRR which requires development of long term databases. This paper examines techniques required to model the SRR, using case studies from Western Australian crustacean fisheries. Outlines of potential problems such as errors and biases in the measurement of stock and recruitment indices, the time series nature of the data, and lack of stationarity in the data, are given with possible solutions. Environmental effects, which can greatly influence the abundance of recruits, may need to be determined before the underlying SRR can be seen. Some of the advantages and possible disadvantages of incorporating environmental variables in the SRR are examined. A thorough assessment of SRRs also involves a study of the impact of fishing on the stock and the effect of stochastic variation using simulations. The evaluation of the SRR requires a multi-disciplinary approach which includes the fields of biology, environment, economics, population dynamics and statistics.

scholarly journals Stock-recruitment models, principles of management and rules for regulating the fishery on the main Chukotka stocks of sockeye and chum salmon

2021 ◽  
Vol 201 (3) ◽  
pp. 735-751
Author(s):  
E. A. Shevlyakov ◽  
M. G. Feldman ◽  
A. N. Kanzeparova
Keyword(s):  
Sockeye Salmon ◽  
Chum Salmon ◽  
Fishery Management ◽  
Pacific Salmon ◽  
Far East ◽  
Simulation Models ◽  
Processing Capacity ◽  
Spawning Stock ◽  
Stock Recruitment ◽  
Recruitment Model

Fishery pressure on populations of pacific salmons has increased in the Rusian Far East in the last decade because of growing fishing and processing capacity, so measures for the fishery regulation are necessary, as the regime of pass days in rivers and marine coastal areas. Chukotka is now almost the only region where such restrictions are still absent. However, if the interest of fishery industry to the stocks of pacific salmon in Chukotka will grow, a successful scientifically based strategy of fishery should be developed to maintain exploitation of the stocks without exceeding the limits of excessive use. Year-to-year time series on spawning stock and recruitment of chum salmon in the Anadyr area and sockeye salmon in the Meynypilgyn area were analysed for development of recruitment models and establishment of general principles for adaptive fishery management. Nonlinear adaptive fishery management based on principles of buffer managing is proposed and tested under various regimes of landing using the stock simulation models accounting deviations from the standard stock-recruitment model. There is concluded that the level of exploitation is much lower than optimal for the Anadyr chum salmon, whereas escapement for spawning of the Meynypilgyn sockeye salmon should be increased in cases of low spawning stock of this species.

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