News » Linefish resilience in the Anthropocene

“Linefish resilience in the Anthropocene”

By: Lucky Dlamini – WWF-SAIAB Communications Intern
Edited by: Penny Haworth – SAIAB Communications Manager

Group picture of some of the delegates who attended the 5th SAMLS conference.

Almost twenty years ago, the South African government declared a linefish emergency which recognised at least 20 key linefish stocks like the White steenbras, Cape salmon, Roman seabream and several species of cod as being dangerously over-exploited. Since then, researchers studying linefish have met on a handful of occasions to share results and find ways to assist government in the management of these over-exploited species. The Southern African Marine Linefish Symposium (SAMLS) held its 5th convention from 8-11 July 2019 at Mpekweni Beach Resort in the Eastern Cape, which was themed “Linefish resilience in the Anthropocene”. The overarching aim was to address the effects that the ever-increasing global human population is having on the planet’s resources, ecosystems and climate. Highlighting these effects, Professor Warren Potts, chairperson of the SAMLS Working Group and SAMLS local organising committee, explained, “We are now in a state of flux with big effects of exploitation and climate stress which are characteristics of the Anthropocene. I think that the linefish populations and linefisheries are at risk. So, the idea of the symposium is to try and collect novel scientific information so as to give the fisheries stocks some kind of resilience and ultimately to use such scientific information to inform policies and management structures, as well as to support the importance of fisheries from a food security perspective.”

The 5th SAMLS offered 43 oral presentations grouped into 10 themed sessions which covered a wide range of topics on linefish research, including monitoring and assessment of linefish and linefisheries; impacts of climate change on linefish and linefisheries; and socio-ecological systems of linefisheries. These themed sessions attempted to establish the current status of South Africa’s marine linefish resources with a strong emphasis on where future research is needed in order to address possible impacts of future climate change.

Monitoring and assessment of linefish and linefisheries

Since the declaration of the linefish emergency in 2000, the continued assessment of fish stocks has been vital in order to enforce increased regulatory frameworks. To focus efforts on rebuilding South Africa’s depleting linefish stocks, the South African government has been responding by proclaiming Marine Protected Areas (MPAs) to address the commercial, recreational and subsistence exploitation of linefish. MPAs involve the protective management of natural areas so as to keep them in their natural state.

Ecologists, like Ms Alexis Olds from CapeNature, are mandated to manage MPAs in the Western Cape such as the Goukamma MPA. Olds gave a presentation titled: The Goukamma Marine Protected Area catch-per-unit-effort monitoring programme – 6 years down the line in which she explained that, in order to protect remaining fish stocks, three MPAs in the Western Cape are potentially being realigned/rezoned. “By doing so, we are hoping to take the pressure off the exploited species and hopefully, this will allow stocks to recover and spill over into the adjoining non-protected areas. This has been motivated by recommendations made as a result of research conducted in our reserves. Based on those recommendations, we are now realigning and rezoning three of our MPAs to increase their performance at conserving our linefish species,” said Olds.

Realigning and rezoning Goukamma MPA means taking an MPA that is currently open to, for example, shore angling and bait collecting but closed to boat angling and rezoning parts of that coastline to be no-take zones which then prohibits fishing or any other extractive activities. Considering this, Olds explained that rezoning would ideally be supported by significant baseline data that can prove or show the effects of rezoning and realignment. “We often face the challenge that we don’t have any baseline information on MPAs before they were rezoned and after they have been rezoned.”

According to Olds, CapeNature’s project is focused on collecting baseline data that will help them after rezoning to determine whether stocks are increasing inside rezoned MPAs as compared to outside MPAs where harvesting is allowed. “What our data shows is that stocks are actually very low within the Goukamma MPA. The catches we are getting are very similar to outside the MPA, which we expect considering they are both open to shore angling. By closing the MPA to shore angling, we are hoping to see an increase in our over exploited fish species especially those from the Sparidae family,” said Olds.

The dynamic nature of linefish stocks and the ever-changing environment in which they live warrants the continued assessment of South Africa’s resources. Working on research recommendations and rezoning MPAs may mean that ecologists, like Olds, become more effective in their work of protecting and replenishing linefish stocks. Such rezoning efforts may also offer a greater amount of protection to the ecosystems, habitats and species within the boundaries of those larger and less restrictive protected areas.

Ms Alexis Olds, ecologist at CapeNature, presented 6-years of progress made on the Goukamma
Marine Protected Area catch-per-unit-effort monitoring programme.

Another presentation that offered new insights into how South Africa’s linefish stocks can be assessed was by Dr Anthony Bernard from the South African Institute for Aquatic Biodiversity (SAIAB). Dr Bernard used baited remote underwater stereo-video systems to test whether depth can provide refuge from fishing for reef-associated linefish species. This research involved comparing linefish abundance and biomass and assemblage structure between shallow (10-30 meters) and deep (40-80 meters) reef habitats from inside and outside four no-take MPAs (Tsitsikamma, Bird Island, Amathole and Pondoland) which are along South Africa’s south and east coasts. Dr Bernard said, “The results from this analysis showed that depth is not a refuge as the deep reefs should be home to adults of many important linefish species, however these fish were all but absent in areas where fishing is permitted.” He further explained that this is likely because fisheries restrictions (such as minimum size limits), fisher preferences for larger fish and historic exploitation of shallow reefs would all promote fishing on deeper reefs that were originally home to large fish. As a result, “No-take MPAs are providing an essential refuge to protect linefish inhabiting deeper reefs.”

Dr Anthony Bernard, scientist at SAIAB, presents his research into whether depth is a natural refuge for
reef-associated linefish species occurring along the east and south coast of South Africa.

Fisheries science and management

Fishes exhibit biological and behavioural changes during their lifetime, often in response to the environment they encounter. For instance, fish growth rates, reproduction, feeding and movement are some of the aspects that have been shown to change in response to exploitation by humans and climate change. Considering this, keynote speaker, Dr Stephen Brouwer, a National Scientist of The Pacific Community (SPC) in Nouméa, New Caledonia, emphasised that fisheries management systems change over time and that management arrangements are only supported by “biological and catch information, while others require data rich systems and fully integrated quantitative stock assessments.” This requires scientists to provide detailed fisheries and biological information, but the systems also require monitoring, surveillance and comprehensive management arrangements in order to be effective in a consistently changing environment.

“The current state of fishery sciences and management in the Anthropocene has to focus on climate change and trying to predict what is going to happen as the ocean warms and changes. The ocean is a dynamic environment, but with climate change it is changing faster and in unexpected ways” said Brouwer. In order to predict what is currently happening and to model what is going to happen in the future, information on fisheries science becomes critical for designing management strategies to enable management organisations to plan for a future aimed at building resilience well into the Anthropocene.

In the midst of uncertainties, Brouwer advised, “Research is now focusing on trying to predict what is going to be happening in 50 to 100 years’ time as distributions of fish change and predicting the ability of fish to live in an ocean that is warmer and more acidic. South Africa has a very good understanding of fish biology and good catch records, so it is important to use these data in a way that is informative for making management decisions.”

Dr Stephen Brouwer, a scientist of The Pacific Community (SPC) in Nouméa, New Caledonia, delivering his
keynote presentation addressing ‘Fisheries science and management – moving targets in the Anthropocene’.

Impacts of climate change on linefish and linefisheries

A warming world poses challenges for many organisms and in particular, ectotherms such as linefish where temperature drives physiological processes in various and complex ways. Dr Murray Duncan, a postdoctoral fellow with Rhodes University’s Ichthyology Department, focused his presentation on understanding the effects of temperature variability on marine linefish in South Africa. Duncan advocated for a paradigm shift in how to think about temperature change effects on organisms, within the climate change framework, towards closer scrutiny into the effects of variability on linefish performance, rather than averaging environmental changes. Duncan explained that taking “ocean weather” into account is an emerging trend in literature. “The South African coastline is highly dynamic. Sea temperatures fluctuate hourly from 8 degrees to 24 degrees Celsius and I think that this trend will probably be the overarching driver on patterns of marine linefish responses to climate change.”

Duncan’s take-home message was that temperature is an important factor when determining the distribution and abundance of linefish. He identified environmental variability or “ocean weather” as possibly having a more pervasive effect on biodiversity. Consequently, predicting the impact of a warming climate on linefish populations requires scientists to use laboratory and modelling experiments to measure thermal niches (preferred temperatures in which to live) and extrapolate results onto future climate scenarios.

Science communication on linefish and linefisheries

During her combined plenary presentation with Dr Bruce Mann, Dr Judy Mann-Lang, Conservation
Strategist at SAAMBR, situated the ‘So What?’ question to South Africa’s new coastal MPAs
and questioned whether fishermen are supportive of MPAs.

There is a global shift towards making research findings freely available to society, through what is called ‘Open Access’ and through the practice of science communication. These approaches are recognised for making research results more accessible as well as contributing to better and more relevant science in the public sphere. Scientific research often helps to answer some of society’s greatest challenges and not all scientists convey their research findings to society. When they do, the outcome of scientific studies is often only published in peer-reviewed journals which most citizens never see or even have access to. Thus, there is a disconnect between scientists, the general public and even management organisations.

Dr Judy Mann-Lang, conservation strategist at the South African Association for Marine Biological Research (SAAMBR), was able to demonstrate that effective cooperation between science and society is an achievable goal. She noted that exploited fishes cannot be managed independently of people, as the goal of fisheries management is to also contribute to and, ideally, maximize human well-being, while conserving natural resources. Mann-Lang presented on, ‘How to communicate more effectively with recreational fishermen’, focusing on how, in the past, fisheries scientists worked on the assumption that by understanding fish biology and ecosystem functioning, they would be able to ensure the sustainable use of marine resources. She explained that “unfortunately, this approach only addressed half of the fisheries equation – the prey.” According to Mann-Lang, this approach did not take into consideration the knowledge, attitudes, motivations and behaviour of fishermen – the predators. She emphasised that “Until scientists learn to communicate effectively with fishermen, many challenges facing fisheries management will remain unresolved.” For this reason, integrating interdisciplinary approaches into fisheries research, management and communication, which include social and economic aspects, is critical.

Science achieves little if it stays in the lab, hence Mann-Lang highlighted novel ways to disseminate scientific information on linefish and linefisheries to a broader audience. The importance of prioritising science communication and interdisciplinary research approaches is to promote better communication links between science, policy and the understanding of target audiences by including their values and making science relevant to people.

Supporting this, Prof Warren Potts also recommended a policy shift that recognises “the promotion of inclusive stakeholder engagement and the initiation of human dimensions monitoring programmes” amongst others, as approaches to improve the benefits and resilience of marine recreational fisheries.

Dr Judy Mann-Lang presenting findings from research in human behaviour change and conservation
psychology, with best practice case studies of effective conservation communication as ways to
guide communication efforts with fishermen in South Africa.

Student Support

The 5th SAMLS was geared towards student development and this 5th edition, in collaboration with SAIAB’s African Coelacanth Ecosystem Programme (ACEP) Phuhlisa Programme, supported the attendance of 25 postgraduate students from Walter Sisulu University and 10 students from the University of Fort Hare on the 10th July. This platform provided the students with learning and networking opportunities, in the hope that they will pursue future research careers in the marine sciences.

In addition to this, the symposium encouraged students to present research project proposals in the form of speed talks as part of the main programme of the symposium. The aim was for the students to receive constructive advice and offers of assistance from expert researchers.

ACEP Phuhlisa Programme Manager, Mr Garth van Heerden (back row, third from left), with some
of the students and their supervisors from the University of Fort Hare and Walter Sisulu
University who attended the second day of the symposium.

Social Media

#SAMLS2019 Twitter posts, tags & retweets (@5Samls)

In a technologically-driven age, social media platforms form an integral part in knowledge-sharing in conferences between delegates and the public. The 5th SAMLS actively engaged on social media (Twitter) and enjoyed significant mentions. Delegates posted tweets about the presentations highlighting the innovative research directed at solving and managing linefishes around southern Africa.

A total of 167 tweets were posted throughout the three days of the conference:



The 5th SAMLS was important as it provided an opportunity for leading Southern African and international marine linefish researchers to communicate on previous and current research on linefish and linefisheries and to identify research gaps that should be tackled in the future in response to anthropogenic impacts.

The SAMLS received support from the National Research Foundation’s Knowledge, Interchange and Collaboration fund, the South African Institute of Aquatic Biodiversity, Rhodes University Department of Ichthyology and Fisheries Science and Springfield Estate. The SAMLS remains committed to contributing to the growth in the understanding and management of linefishes around southern Africa.