Incorporating demographic information into spawner-recruit analyses alters biological reference point estimates for a western Alaska population

Changes over time in age, sex, and length-at-age of returning Pacific salmon have been widely observed, suggesting concurrent declines in per capita reproductive output. Thus, assessment models assuming stationary reproductive output may inaccurately estimate biological reference points that inform harvest policies. We extended age-structured state-space spawner-recruit models to accommodate demographic time trends and fishery selectivity to investigate temporal changes in reference points using Kuskokwim River Chinook salmon (<i>Oncorhynchus tshawytscha</i>). We illustrate that observed demographic changes have likely reduced per capita reproductive output in an additive manner, for example, models including changes in both length-at-age or age composition showed larger declines than models incorporating only one time trend. Translated into biological reference points using a yield-per-recruit algorithm, we found escapement needed for maximum sustained catch has likely increased over time, but the magnitude further depended on size-selective harvest (i.e., larger changes for reference points based on larger mesh gillnets). Compared to traditional salmon assessments, our approach that acknowledges demographic time trends allows more complete use of available data and facilitates evaluating trade-offs among gear-specific harvest policies.

Download Full-text

Evaluation of methods for spawner–recruit analysis in mixed-stock Pacific salmon fisheries

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2019-0281 ◽

2020 ◽

Vol 77 (7) ◽

pp. 1149-1162 ◽

Cited By ~ 3

Author(s):

Benjamin A. Staton ◽

Matthew J. Catalano ◽

Brendan M. Connors ◽

Lewis G. Coggins ◽

Michael L. Jones ◽

...

Keyword(s):

State Space ◽

Oncorhynchus Tshawytscha ◽

Pacific Salmon ◽

State Space Model ◽

Reference Points ◽

State Space Models ◽

Space Model ◽

Trade Offs ◽

Salmon Fisheries ◽

Mixed Stock

Salmon populations harvested in mixed-stock fisheries can exhibit genotypic, behavioral, and life history diversity that can lead to heterogeneity in population productivity and size. Methods to quantify this heterogeneity among populations in mixed-stock fisheries are not well-established but are critical to assessing harvest–biodiversity trade-offs when setting harvest policies. We developed an integrated, age-structured, state-space model that allows for more complete use of available data and sharing of information than simpler methods. We compared a suite of state-space models of varying structural complexity to simpler regression-based approaches and, as an example case, fitted them to data from 13 Chinook salmon (Oncorhynchus tshawytscha) populations in the Kuskokwim drainage in western Alaska. We found biological and policy conclusions were largely consistent among state-space models but differed strongly from regression-based approaches. Simulation trials illustrated our state-space models were largely unbiased with respect to spawner–recruit parameters, abundance states, and derived biological reference points, whereas the regression-based approaches showed substantial bias. These findings suggest our state-space model shows promise for informing harvest policy evaluations of harvest–biodiversity trade-offs in mixed-stock salmon fisheries.

Download Full-text

Stock assessment and projections incorporating discard estimates in some years: an application to the hake stock in ICES Divisions VIIIc and IXa

ICES Journal of Marine Science ◽

10.1093/icesjms/fsq029 ◽

2010 ◽

Vol 67 (6) ◽

pp. 1185-1197 ◽

Cited By ~ 16

Author(s):

C. Fernández ◽

S. Cerviño ◽

N. Pérez ◽

E. Jardim

Keyword(s):

Time Series ◽

Stock Assessment ◽

Reference Points ◽

Assessment Model ◽

Marine Science ◽

Fishing Mortality ◽

Change Over Time ◽

Age Structured ◽

Available Information ◽

Over Time

Abstract Fernández, C., Cerviño, S., Pérez, N., and Jardim, E. 2010. Stock assessment and projections incorporating discard estimates in some years: an application to the hake stock in ICES Divisions VIIIc and IXa. – ICES Journal of Marine Science, 67: 1185–1197. A Bayesian age-structured stock assessment model is developed to take into account available information on discards and to handle gaps in the time-series of discard estimates. The model incorporates mortality attributable to discarding, and appropriate assumptions about how this mortality may change over time are made. The result is a stock assessment that accounts for information on discards while, at the same time, producing a complete time-series of discard estimates. The method is applied to the hake stock in ICES Divisions VIIIc and IXa, for which the available data indicate that some 60% of the individuals caught are discarded. The stock is fished by Spain and Portugal, and for each country, there are discard estimates for recent years only. Moreover, the years for which Portuguese estimates are available are only a subset of those with Spanish estimates. Two runs of the model are performed; one assuming zero discards and another incorporating discards. When discards are incorporated, estimated recruitment and fishing mortality for young (discarded) ages increase, resulting in lower values of the biological reference points Fmax and F0.1 and, generally, more optimistic future stock trajectories under F-reduction scenarios.

Download Full-text

Incorporating harvest–population diversity trade-offs into harvest policy analyses of salmon management in large river basins

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2019-0282 ◽

2020 ◽

Vol 77 (6) ◽

pp. 1076-1089 ◽

Cited By ~ 5

Author(s):

Brendan M. Connors ◽

Benjamin Staton ◽

Lewis Coggins ◽

Carl Walters ◽

Mike Jones ◽

...

Keyword(s):

Oncorhynchus Tshawytscha ◽

Large River ◽

Population Diversity ◽

Equitable Access ◽

Policy Performance ◽

Trade Offs ◽

The Cost ◽

Mixed Stock ◽

Harvest Policies

Accounting for population diversity can be critical to the sustainable management of mixed-stock fisheries because harvest rates that can be sustained by productive populations may come at the cost of overfishing less productive ones. While these harvest–diversity trade-offs are well-recognized, their consequences for harvest policy performance are not often explicitly evaluated in contemporary fisheries management. We use closed-loop simulations to evaluate the ability of alternative harvest policies to meet population diversity and fishery objectives for one of the largest subsistence Chinook salmon (Oncorhynchus tshawytscha) fisheries in the world (Kuskokwim River Basin in western Alaska). We found clear evidence of population diversity that resulted in asymmetric trade-offs among fishery and conservation objectives whereby policies that forgo relatively small amounts of harvest result in relatively large increases in equitable access to Chinook and elimination of risk of weak stock extirpation. The performance of alternative harvest policies, and the magnitude of trade-offs, were sensitive to regime shifts and uncertainty in the drivers of recruitment variation. However, we found that harvest policies that prioritized meeting minimum subsistence needs were unlikely to jeopardize long-term sustainability.

Download Full-text

Dispersal and productivity of Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon colonizing newly accessible habitat

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2014-0180 ◽

2015 ◽

Vol 72 (3) ◽

pp. 454-465 ◽

Cited By ~ 18

Author(s):

Joseph H. Anderson ◽

Paul L. Faulds ◽

Karl D. Burton ◽

Michele E. Koehler ◽

William I. Atlas ◽

...

Keyword(s):

Chinook Salmon ◽

Oncorhynchus Tshawytscha ◽

Coho Salmon ◽

Pacific Salmon ◽

Oncorhynchus Kisutch ◽

Population Expansion ◽

Fishing Mortality ◽

Fish Ladder ◽

Accessible Habitat ◽

Over Time

Following construction of a fish ladder at Landsburg Diversion Dam on the Cedar River, Washington, USA, in fall 2003, we used DNA-based parentage to identify second generation Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon as recruits that were produced above the dam or “strays” dispersing into the new habitat that were produced elsewhere. For both species, strays colonized immediately but decreased as a proportion of the total run over time. Chinook salmon strays were more numerous in years when the species was more abundant below the dam and included a much larger proportion of hatchery origin salmon than did coho salmon. Productivity, calculated as the ratio of female recruits sampled at the dam to female spawners, exceeded replacement in all four coho salmon cohorts but only two of five Chinook salmon cohorts, leading to more rapid population expansion of coho salmon. However, estimates of fishing mortality and recruitment into the Cedar River below the dam substantially increased Chinook salmon productivity estimates. Our results demonstrate that Pacific salmon are capable of rapidly recolonizing habitat made accessible by restoration and emphasize the importance of demographic exchange with preexisting populations during the transition from recolonization to self-sustainability.

Download Full-text

Distinguishing benchmarks of biological status from management reference points: A case study on Pacific salmon in Canada

Environmental Conservation ◽

10.1017/s0376892913000209 ◽

2013 ◽

Vol 40 (4) ◽

pp. 345-355 ◽

Cited By ~ 5

Author(s):

CARRIE A. HOLT ◽

JAMES R. IRVINE

Keyword(s):

Sockeye Salmon ◽

Pacific Salmon ◽

Reference Points ◽

Biological Information ◽

Isolated Populations ◽

Trade Offs ◽

Socioeconomic Considerations ◽

Public Consultations

SUMMARYFor fisheries with multiple, competing objectives, identifying and applying reference points for management can present difficult trade-offs between long-term biological and shorter-term socioeconomic considerations. The term biological benchmarks is proposed to demarcate zones of population status based on conservation and production considerations. These scientifically derived benchmarks contrast with management reference points that generally require additional shorter-term socioeconomic information best obtained through public consultations. This paper illustrates the distinction between biological benchmarks and management reference points with a case study on Pacific salmon (Oncorhynchusspp.). In Canada, the management and assessment of wild Pacific salmon are guided by a major 2005 conservation policy, which calls for the identification of biological benchmarks to categorize status of demographically isolated populations, and decision-support tools, such as management reference points, to integrate biological information with appropriate social and economic information. In the Fraser River (British Columbia, Canada), the selection of management reference points for sockeye salmon (O. nerka) fisheries explicitly considered trade-offs between the probability of meeting long-term biological objectives on component populations and harvest objectives on population aggregates. Decisions about reference points were made in a consultative process that included extensive stakeholder engagement. Other agencies are urged to distinguish biological benchmarks from management reference points to ensure transparency in the relative influence of biological versus socioeconomic information in decision making.

Download Full-text

An age-structured state-space stock–recruit model for Pacific salmon (Oncorhynchusspp.)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2012-0112 ◽

2013 ◽

Vol 70 (3) ◽

pp. 401-414 ◽

Cited By ~ 26

Author(s):

Steven J. Fleischman ◽

Matthew J. Catalano ◽

Robert A. Clark ◽

David R. Bernard

Keyword(s):

State Space ◽

Oncorhynchus Tshawytscha ◽

Pacific Salmon ◽

State Space Model ◽

Auxiliary Information ◽

Observation Error ◽

Age Composition ◽

Probability Profile ◽

Explicit Consideration ◽

Age Structured

We describe an age-structured state-space model for stock–recruit analysis of Pacific salmon data. The model allows for incorporation of process variation in stock productivity, recruitment, and maturation schedules, as well as observation error in run abundance, harvest, and age composition. Explicit consideration of age structure allows for realistic depiction of system dynamics and sample design, more complete use of recent data, and forecasts that consider sibling relationships. A Bayesian framework is adopted, implemented with Markov chain Monte Carlo methods, which provides an enhanced ability to incorporate auxiliary information, convenient and rigorous consideration of measurement error and missing data, and a more complete assessment of uncertainty. We fit the model to annual upstream weir counts, commercial and recreational harvest estimates, and age composition data from Chinook salmon (Oncorhynchus tshawytscha) in Karluk River, Alaska. For the case study, the model is configured with a Ricker stock–recruit relationship, autoregressive lag-1 productivity, and Dirichlet age-at-maturity. Details of alternate configurations are also described. We introduce the optimal yield probability profile as an objective tool for informing the selection of escapement goals based on yield considerations and describe alternative versions useful for addressing other management questions.

Download Full-text

Decision Processes and Value Endogeneity

10.1093/oso/9780198825067.003.0004 ◽

2018 ◽

Author(s):

James G. March

Keyword(s):

Decision Processes ◽

Hard Problem ◽

Trade Offs ◽

Definition Of ◽

Over Time ◽

What Matters

Humans use reasons to shape and justify choices. In the process, trade-offs seem essential and often inevitable. But trade-offs involve comparisons, which are problematic both across values and especially over time. Reducing disparate values to a common metric (especially if that metric is money) is often problematic and unsatisfactory. Critically, it is not that values just shape choices, but that choices themselves shape values. This endogeneity of values makes an unconditional normative endorsement of modern decision-theoretic rationality unwise. This is a hard problem and there is no escaping the definition of good values, that is, those that make humans better. This removes the wall between economics and philosophy. If we are to adopt and enact this perspective, then greater discourse and debate on what matters and not just what counts will be useful and even indispensable.

Download Full-text

Time trends of socioeconomic inequalities in adolescent smoking in Okinawa, Japan, 2008–2016: a repeated cross-sectional study

Environmental Health and Preventive Medicine ◽

10.1186/s12199-021-00948-y ◽

2021 ◽

Vol 26 (1) ◽

Author(s):

Minoru Takakura ◽

Masaya Miyagi ◽

Akira Kyan

Keyword(s):

Time Trends ◽

Parental Education ◽

Cross Sectional Study ◽

Socioeconomic Inequalities ◽

School Type ◽

Sectional Study ◽

Cross Sectional ◽

Japanese Adolescents ◽

Index Of Inequality ◽

Over Time

Abstract Background Smoking among Japanese adolescents has decreased noticeably. However, little is known whether the decreasing trend in adolescent smoking can be seen across all socioeconomic status (SES) groups. This study aimed to examine trends in socioeconomic inequalities in smoking among Japanese adolescents between 2008 and 2016. Methods We conducted a repeated cross-sectional study using data from three surveys of high school students in Okinawa, Japan, in 2008, 2012, and 2016. The study participants consisted of 7902 students in grades 10 through 12 (15–18 years). Smoking was assessed as current cigarette use. SES indicators included familial SES (parental education and family structure) and student’s own SES (school type). To evaluate absolute and relative inequalities, prevalence differences (PDs) and ratios (PRs) between low and high SES groups were estimated. The slope index of inequality (SII) and relative index of inequality (RII) were also calculated. Results Smoking prevalence among boys and girls significantly declined from 11.5% and 6.2% in 2008 to 4.7% and 1.9% in 2016, respectively. Similar decreasing trends in smoking were found among most of the SES groups. The PDs and SII for parental education in boys and family structure in girls decreased over time while those for school type persisted among boys and girls. The PRs and RII for school type in boys increased while those for other SES indicators among both sexes remained stable over time. Conclusions Smoking among Japanese adolescents has been declining and time trends of socioeconomic inequalities in smoking varied by absolute and relative measures. Further policies and/or interventions to reduce smoking inequalities should focus on the context of schools, especially in vocational high schools.

Download Full-text

Frequency responses of age-structured populations: Pacific salmon as an example

Theoretical Population Biology ◽

10.1016/j.tpb.2010.07.004 ◽

2010 ◽

Vol 78 (4) ◽

pp. 239-249 ◽

Cited By ~ 27

Author(s):

Lee Worden ◽

Louis W. Botsford ◽

Alan Hastings ◽

Matthew D. Holland

Keyword(s):

Pacific Salmon ◽

Structured Populations ◽

Frequency Responses ◽

Age Structured

Download Full-text

Non-Price Criteria for the Evaluation of the Tender Offers in Public Procurement of Ukraine

International Journal of Financial Studies ◽

10.3390/ijfs8030044 ◽

2020 ◽

Vol 8 (3) ◽

pp. 44

Author(s):

Alexander Baranovsky ◽

Nataliia Tkachenko ◽

Vladimer Glonti ◽

Valentyna Levchenko ◽

Kateryna Bogatyrova ◽

...

Keyword(s):

Public Procurement ◽

Well Being ◽

Gdp Per Capita ◽

Tender Offers ◽

Product Categories ◽

Per Capita ◽

The Government ◽

The Impact ◽

Over Time ◽

The Eu

Traditionally, public procurement has been associated with the measurement of achieving savings. However, recent research shows that the economic impact of public procurement is not limited only to savings, but by measuring the impact of four capitals—natural, human, social, and economic—on sustainable well-being over time. Ukraine is a country with a very low gross domestic product (GDP) per capita, which exacerbates the problem of the impact of public procurement results on the population’s welfare. Ukrainian public procurement legislation allows customers to apply non-price criteria (the share of non-price criteria cannot be more than 70%), which, together, are taken into account in the formula of the quoted price. The studies show that the effect of the use of non-price criteria depends on the relevance of the method of the evaluation of non-price criteria. The most important non-price criteria for Ukrainian customers by product categories and the methods of their evaluation are analyzed according to the Bi.prozorro.org analytics module. Therefore, it is concluded that the quoted price method, which is used in Ukrainian practice, is not relevant in comparison with the method used in the EU. A survey of the government buyers on the practice of applying non-price criteria was conducted, and the areas of their use were identified.

Download Full-text