scholarly journals Unveiling the recovery dynamics of Walleye after the invisible collapse

2021 ◽  
Author(s):  
Christopher L. Cahill ◽  
Carl J. Walters ◽  
Andrew J. Paul ◽  
Michael G. Sullivan ◽  
John R. Post
Keyword(s):  
Population Dynamics ◽  
Monitoring Program ◽  
Fisheries Science ◽  
Science Models ◽  
New Information ◽  
Stock Recruitment ◽  
Age Structured ◽  
Population Dynamics Models ◽  
Recovery Dynamics ◽  
The Invisible

Walleye (Sander vitreus) populations in Alberta, Canada collapsed by the mid-1990s and were a case study in the paper Canada’s Recreational Fisheries: The Invisible Collapse? Here we fit age-structured population dynamics models to data from a landscape-scale monitoring program to assess Walleye population status and reconstruct recruitment dynamics following the invisible collapse. Assessments indicated that populations featured low F_msy values of approximately 0.2-0.3 under conservative assumptions for the stock-recruitment relationship but that many populations were lightly exploited during 2000-2018. Recruitment reconstructions showed that recovery from collapse in 33/55 lakes was driven in part by large positive recruitment anomalies that occurred during 1998-2002. Additionally, 15/55 lakes demonstrated cyclic recruitment dynamics. Both the recruitment anomalies and cyclic fluctuations could be due to environmental effect(s) and(or) cannibalism, and experimentation may be necessary to resolve this uncertainty. These findings contribute new information on the recovery dynamics of Walleye following the invisible collapse, and demonstrate the effectiveness of coupling traditional fisheries science models with broad-scale monitoring data to improve understanding of population dynamics and sustainability across landscapes.

Age-structured & Size-structured Population Dynamics Models

2009 ◽  
Author(s):  
Mohamed O. El-Doma ◽  
Theodore E. Simos ◽  
George Psihoyios ◽  
Ch. Tsitouras
Keyword(s):  
Population Dynamics ◽  
Structured Population ◽  
Structured Population Dynamics ◽  
Age Structured ◽  
Population Dynamics Models ◽  
Dynamics Models

POTENTIAL YIELD OF A ROCK SHRIMP STOCK, SICYONIA PENICILLATA IN THE NORTHERN GULF OF CALIFORNIA

Crustaceana ◽  
1999 ◽  
Vol 72 (6) ◽  
pp. 581-590 ◽  
Author(s):  
Juana Lopez-Martinez ◽  
Edgar Alcantara-Razo ◽  
Sergio Hernandez-Vazquez ◽  
Ernesto Chavez
Keyword(s):  
Gulf Of California ◽  
Age Groups ◽  
Potential Yield ◽  
Natural Oscillations ◽  
Recruitment Pattern ◽  
Stock Recruitment ◽  
Age Structured ◽  
Stochastic Recruitment ◽  
Age Structured Model ◽  
Compensatory Effect

AbstractA stock of rock shrimp Sicyonia penicillata was assessed in a fishery recently opened at Bahoa Kino, Sonora, Mexico. An age-structured model with stochastic recruitment was developed, which considers growth rate, natural mortality, and fishing mortality by age. Age groups were followed year by year with a stock-recruitment Ricker function where the seasonal recruitment pattern was defined as well. Simulations might be interpreted as showing a stable population with four year cycles, reflecting a density-dependent process. In 1996, fishing intensity had an apparent compensatory effect on the stock, decreasing the amplitude of natural oscillations and maintaining the stock at a biomass level similar to the size observed in a condition of no exploitation. The stock was found currently underexploited. As a result of the seasonal accessibility and the age of first-catch fishing (adult shrimp), the stock might be capable to withstand high fishing pressure without being overexploited. Se evaluo una poblacion de camaron de roca Sicyonia penicillata, de una pesqueroa recientemente abierta en Bahoa Kino, Sonora, Mexico. Se desarrollo un modelo basado en la estructura por edades que considera reclutamiento estocastico, tasa de crecimiento, mortalidad natural y mortalidad por pesca por grupo de edad. Estos grupos de edad fueron determinados ano tras ano mediante la funcion de reclutamiento de Ricker, en los que tambien se definio el patron estacional de reclutamiento. Las simulaciones muestran una poblacion estable con ciclos de cuatro anos, que indican un proceso de densodependencia. En 1996, la intensidad de pesca tuvo un efecto compensatorio sobre la poblacion, reduciendo la amplitud de las oscilaciones naturales y manteniendo al stock en un nivel de biomasa similar al observado en la condicion sin explotacion. Se encontro que el recurso esta subexplotado. Como resultado de la accesibilidad estacional y de que la edad de primera captura corresponde a camaron adulto, el recurso soporta alta presion de pesca sin dar evidencias de sobreexplotacion.

Stability analysis of age-structured disabled population dynamics

2009 ◽  
Vol 43 (1) ◽  
pp. 72-74
Author(s):  
Peng Jigen ◽  
Song Xueli ◽  
Zhang Xiangqin
Keyword(s):  
Population Dynamics ◽  
Stability Analysis ◽  
Age Structured

Nonlinear Population Dynamics: Models, Experiments and Data

1998 ◽  
Vol 194 (1) ◽  
pp. 1-9 ◽  
Author(s):  
J.M. Cushing ◽  
R.F. Costantino ◽  
Brian Dennis ◽  
R.A. Desharnais ◽  
Shandelle M. Henson
Keyword(s):  
Population Dynamics ◽  
Population Dynamics Models ◽  
Dynamics Models

scholarly journals The status of Japanese fisheries relative to fisheries around the world

2017 ◽  
Vol 74 (5) ◽  
pp. 1277-1287 ◽  
Author(s):  
Momoko Ichinokawa ◽  
Hiroshi Okamura ◽  
Hiroyuki Kurota
Keyword(s):  
Maximum Sustainable Yield ◽  
Production Model ◽  
Structured Population Model ◽  
Total Allowable Catch ◽  
Quick Recovery ◽  
Stock Status ◽  
Surplus Production Model ◽  
The Status ◽  
Stock Recruitment ◽  
Age Structured

We present the first quantitative review of the stock status relative to the stock biomass (B) and the exploitation rate (U) that achieved the maximum sustainable yield (MSY) (BMSY and UMSY, respectively) for 37 Japanese stocks contributing 61% of the total marine capture production in Japan. BMSY and UMSY were estimated by assuming three types of stock-recruitment (S-R) relationships and an age-structured population model or by applying a surplus production model. The estimated stock status shows that approximately half of the stocks were overfishing (U/UMSY > 1), and approximately half of the stocks were overfished (B/BMSY < 0.5) during 2011–2013. Over the past 15 years, U decreased and B slightly increased on average. The rate of decrease in the U of the stocks managed by the total allowable catch (TAC) was significantly greater than that of the other stocks, providing evidence of the effectiveness of TAC management in Japan. The above statuses and trends were insensitive to the assumption of the S-R relationship. The characteristics of Japanese stocks composed mainly of resources with relatively high natural mortality, i.e. productivity, suggest that Japanese fisheries have great potential of exhibiting a quick recovery and increasing their yield by adjusting the fishing intensity to an appropriate level.

scholarly journals Modelling and forecasting stock–recruitment: current and future perspectives

2014 ◽  
Vol 71 (8) ◽  
pp. 2307-2322 ◽  
Author(s):  
Sam Subbey ◽  
Jennifer A. Devine ◽  
Ute Schaarschmidt ◽  
Richard D.M. Nash
Keyword(s):  
Present State ◽  
Future Perspectives ◽  
Environmental Covariates ◽  
Explanatory Variables ◽  
Fisheries Science ◽  
The Past ◽  
Methodological Challenges ◽  
Stock Recruitment ◽  
Modelling And Forecasting

AbstractThis paper presents a brief review of the present state of knowledge in stock–recruitment forecasting, including process and current methodological challenges to predicting stock–recruitment. The discussion covers the apparent inability of models to accurately forecast recruitment even when environmental covariates are included as explanatory variables. The review shows that despite the incremental success in the past hundred years, substantial challenges remain if the process of modelling and forecasting stock–recruitment is to become relevant to fisheries science and management in the next 100 years.

scholarly journals Challenging population dynamics models with new data: how accurate were our inferences?

2020 ◽  
Vol 27 (1) ◽  
pp. 008-016
Author(s):  
Verónica C. Andreo ◽  
Mauricio Lima ◽  
Jaime J. Polop ◽  
M. Cecilia Provensal
Keyword(s):  
Population Dynamics ◽  
Population Dynamics Models ◽  
Dynamics Models
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