Henning Winker

Henning Winker
European Commission | ec · Joint Research Centre (JRC)

PhD Fisheries Sciences

About

180
Publications
63,031
Reads
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2,672
Citations
Introduction
My general research interests could be placed within the wider field of fisheries ecology and specifically revolve around life history adaptation, population dynamics and stock assessment methods.My current research specifically focuses on the assessments of large pelagic tuna, billfish and sharks, globally, and improving assessment methods for data poor to moderate fisheries in South Africa.
Additional affiliations
March 2020 - present
European Commission
Position
  • Researcher
December 2016 - February 2020
Department of Agriculture, Forestry and Fisheries, South Africa
Position
  • Researcher
June 2014 - November 2016
South African National Biodiversity Institute
Position
  • Researcher
Education
January 2007 - December 2010
Rhodes University
Field of study
  • Ichthyology and Fisheries Sciences
September 2004 - September 2005
University of Plymouth
Field of study
  • Applied Fish Biology

Publications

Publications (180)
Preprint
Full-text available
13 Identifying species at risk of extinction is necessary to prioritise conservation efforts. The International 14 Union for Conservation of Nature's (IUCN) Red List of Threatened Species is the global standard for 15 quantifying extinction risk, with many species categorised according to population reduction thresholds. 16 We introduce the Bayesia...
Article
Full-text available
The natural mortality rate (M) of a fish stock is typically highly influential on the outcome of age-structured stock assessment models, but at the same time extremely difficult to estimate. In data-limited stock assessments, M usually relies on a range of empirically or theoretically derived M estimates, which can vary vastly. This article aims at...
Article
Full-text available
Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goal...
Article
Full-text available
Integrated analysis has increasingly been the preferred approach for conducting stock assessments and providing the basis for management advice for fish and invertebrate stocks around the world. Many decisions are required when developing integrated stock assessments. For example, the analyst needs to decide whether the model fits the data, if the...
Technical Report
Full-text available
This ad hoc report first reviews the technical details of the Generalised Linear Mixed effects Model (GLMM) approach that is applied to estimate model-based indicators for the performance of the Common Fisheries Policy. It then presents the results a suitability study of applying the Bayesian State-Space model ‘JARA’ as an alternative to the curren...
Preprint
Full-text available
The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endanger...
Technical Report
Full-text available
Management Strategy Evaluation of small pelagic stocks of the Adriatic. MSE carried out for Sardines and Anchovies in GSA17/18. Harvest control rules tuned and evaluated against robustness test. Work carried out in the FLR framework.
Preprint
Full-text available
The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endanger...
Article
Full-text available
This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Abstract This study evaluates the relationship between both commercial and scientific spatial fisheries data and a new satellite-based estimate o...
Article
Full-text available
Supplementary Information of : Mesoscale productivity fronts and local fishing opportunities in the European Seas. Fish and Fisheries, 00, 1–21. https://doi.org/10.1111/faf.12585
Technical Report
Full-text available
This publication is a Science for Policy report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a policy position of the European Commission. Neither the European Comm...
Article
Full-text available
The adoption of the Precautionary Approach requires providing advice that is robust to uncertainty. Therefore, when conducting stock assessment alternative, model structures and data sets are commonly considered. The primary diagnostics used to compare models are to examine residuals patterns to check goodness-of-fit and to conduct retrospective an...
Article
Full-text available
Catch-only models (COMs) have been the focus of ongoing research into data-poor stock assessment methods. Two of the most recent models that are especially promising are (i) CMSY+, the latest refined version of CMSY that has progressed from Catch-MSY, and (ii) SRA+ (Stock Reduction Analysis Plus). Comparing COMs and evaluating their relative perfor...
Technical Report
Full-text available
Red list assessment of Dasyatis chrysonata
Article
Mustelus mustelus from the Langebaan Marine Protected Area (LMPA) has been largely protected from fishing activities for the past 30 years; therefore, its biology represents those of an unfished stock. The reproductive biology, diet, growth and maturity of M. mustelus was studied in the Langebaan Lagoon region in the southwestern Cape Coast of Sout...
Method
Full-text available
CMSY++ is an advanced state-space Bayesian method for stock assessment that estimates fisheries reference points (MSY, Fmsy, Bmsy) as well as status or relative stock size (B/Bmsy) and fishing pressure or exploitation (F/Fmsy) from catch and (optionally) abundance data, a prior for resilience or productivity (r), and broad priors for the ratio of b...
Article
Full-text available
Phenotypic plasticity in life-history traits in response to heterogeneous environments has been observed in a number of fishes. Conversely, genetic structure has recently been detected in even the most wide ranging pelagic teleost fish and shark species with massive dispersal potential, putting into question previous expectations of panmixia. Shall...
Article
The fine-scale movement of Mustelus mustelus in relation to environmental conditions was investigated at various temporal scales with acoustic telemetry and temperature–depth transmitters inside a coastal marine protected area in South Africa. Twenty-four sharks were equipped with acoustic tags and logged by an array of 28 acoustic receivers from N...
Technical Report
Full-text available
Soupfin sharks (Galeorhinus galeus), globally referred to as tope, are medium sized sharks that are globally distributed in temperate waters. Soupfin sharks were the first shark species to be commercially harvested in South Africa and remains one of the top five most commercially valuable shark species. The species is currently caught in the demers...
Technical Report
Full-text available
This workshop is the third in a series of workshops on guidelines for developing Management Strategy Evaluations (MSEs) within ICES, and was intended to explore some of the issues that arose out of workshops that actually developed MSEs for a range of ICES stocks since the second MSE guidelines workshop was held in early 2019. It is intended that r...
Article
Full-text available
Managing coastal fisheries is challenging as the status of many fish stocks caught in these fisheries remains unknown. In the South African linefishery, regular comprehensive assessments of the status of most linefish stocks are unattainable owing to a scarcity of reliable long-term data. Length-based analysis remains the only option to determine s...
Article
Full-text available
To further implement an ecosystem approach to management of the small pelagic fishery in South Africa, we attempted to develop functional relationships between spatialised time-series of the biomass of three small pelagic fish species and the catch per unit effort (CPUE) of four linefish species (i.e. species caught on hook and line, excluding long...
Technical Report
Full-text available
Albacore, Thunnus alalunga, is the main target of the South African tuna pole-line (baitboat) fleet operating along the west and south west coast of South Africa. The South African catch is the second largest in the region with annual landings of around 4000 t. A standardization of the CPUE of the South African baitboat fleet for the time series 20...
Technical Report
Full-text available
Bayesian State-Space Surplus Production Models were fitted to South Atlantic albacore (Thunnus alalunga) catch and CPUE data using the 'JABBA' R package. In accordance with the 2019 SCRS work plan (update of the 2016 assessment), this document presents four preliminary scenarios that explore two production functions (Schaefer or Fox) as well as two...
Article
Full-text available
This paper presents a new, updated, temporally dynamic Ecosim model for the Southern Benguela (1978–2015) by capturing recent advancements in our understanding of the dynamics and newly available data series from an additional decade of research in the region. The paper documents the model development and the thinking behind incorporating a newly a...
Technical Report
Full-text available
Bayesian State-Space Surplus Production Models were fitted to Mediterranean swordfish (Xiphias gladius) catch and CPUE data using the 'JABBA' R package. For the 'Reference' model we used a Schaefer model with an existing r prior, while for the 'ASEM' model we developed a Pella-Tomlinson model based on priors derived from an Age-structured Equilibri...
Article
Full-text available
Understanding changes in abundance is crucial for conservation, but population growth rates often vary over space and time. We use 40 years of count data (1979–2019) and Bayesian state‐space models to assess the African penguin Spheniscus demersus population under IUCN Red List Criterion A. We deconstruct the overall decline in time and space to id...
Chapter
Full-text available
This contribution presents the detailed responses to the peer-review of Froese et al. (2019) "Estimating stock status from relative abundance and resilience" (ICES J. Mar. Sci. 2019) which outlined a method called "AMSY" for inferring biomass trends for stocks for which only catch-per-unit-effort and limited ancillary ('priors') data are available....
Preprint
Full-text available
African Penguin Spheniscus demersus numbers have declined steadily over three generations, resulting in a loss of nearly 60% since of 1989. The breeding population reached an historic low of ~20,850 pairs in 2019. We use count data and JARA, a generalized Bayesian state-space tool for estimating extinction risk estimates under IUCN Red List Criteri...
Technical Report
Full-text available
Bayesian State-Space Surplus Production Models were fitted to Atlantic blue marlin (Kajikia albida) catch and CPUE data using the open-source stock assessment tool JABBA. The three scenarios (S1-sensitivity run 1, S2-sensitivity run 2 and S3-base case model) were based on sensitivity analysis of the initial runs, which corresponded to a 'steepness-...
Technical Report
Full-text available
Bayesian State-Space Surplus Production Models were fitted to yellowfin tuna catch and standardized catch-per-unit-effort (CPUE) data using the open-source stock assessment tool JABBA. Here, we present results from six scenarios (base case model and S1-S5).These scenarios corresponded to combinations of different CPUEs associated with three alterna...
Article
Full-text available
The Law of the Sea and regional and national laws and agreements require exploited populations or stocks to be managed so that they can produce maximum sustainable yields. However, exploitation level and stock status are unknown for most stocks because the data required for full stock assessments are missing. This study presents a new method [abund...
Technical Report
Full-text available
Common smoothhound shark (Mustelus mustelus) are medium sized sharks distributed from the Mediterranean down to the SouthWest Indian Ocean. Commercially it is one of the top five most valuable shark species mainly caught as target or by-catch by the demersal shark longline fishery, commercial linefishery and the inshore trawl fishery. Total catches...
Article
Fish population processes could exhibit non-stationary behaviour as a stochastic biological process with temporal autocorrelation that may be influenced by environmental changes. Here we developed a Bayesian autoregressive state-space surplus production modelling framework to explore potential non-stationarity in population processes. We then evalu...
Article
Full-text available
The Cape Gannet Morus capensis is one of several seabird species endemic to the Benguela upwelling ecosystem (BUS) but whose population has recently decreased, leading to an unfavourable IUCN Red List assessment. Application of ‘JARA’ (‘Just Another Red-List Assessment,’ a Bayesian state-space tool used for IUCN Red List assessments) to updated inf...
Article
Full-text available
The International Union for Conservation of Nature's (IUCN) Red List is the global standard for quantifying extinction risk but assessing population reduction (criterion A) of wide-ranging, long-lived marine taxa remains difficult and controversial. We show how Bayesian state-space models (BSSM), coupled with expert knowledge at IUCN Red List works...