The global footprint of bottom trawling is smaller than we think

The global footprint of bottom trawling is not as large as many assume and varies dramatically by region. For example, at the extremes, just 0.4% of the seabed off Southern Chile is trawled, compared to 80% of the Adriatic Sea off the coast of Italy. On South Africa’s west coast, between 12 and 14% of the continental shelf is trawled, while on the south coast, 9 to 11% of the seabed is trawled. Trawling is for hake, a South African seafood staple and the basis of a sustainable and successful export industry.

A paper that attempts to quantify the global extent of trawling was published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS) earlier this month. South African scientists, Deon Durholtz, Tracey Fairweather and Rob Leslie, who work for the Department of Agriculture, Forestry and Fisheries, were part of a team of 57 fisheries scientists led by Ricardo Amoroso of the University of Washington, who used a combination of satellite tracking data and the logbooks of fishing skippers and scientific observers to collate very precise information about the extent of bottom trawling and dredging on the continental shelves of 24 ocean regions, including North America, South America, Africa, Australia and New Zealand. The study excluded some regions where the quality of data was poor, notably in Asia, but it still represents the most comprehensive and accurate study of the global footprint of bottom trawling ever conducted.

Nearly all bottom-trawling, a method of fishing that involves dragging a weighted net along the seafloor to scoop up fish, occurs on continental shelves or slopes – the relatively shallow areas off the coasts of landmasses that eventually slope down into the deep sea. These areas are mostly shallower than 500m.

Bottom trawling is used to catch about 19 million tons of fish per year – about a quarter of all the fish caught in the world – but it has been criticised for causing damage to the seabed and triggering the depletion of fish stocks that live there, partly based on very high estimates of the areas affected.

The paper Bottom trawl fishing footprints on the world’s continental shelves, rolls back some of this criticism because it uses high definition data to show that the impact of trawling is much less than previously thought. Overall, 14% of the seafloor was trawled in the areas where high resolution data were available over the 2 to 6-year study period. Europe had the highest trawling footprint, while Australia and New Zealand had footprints below 10%.

Previous studies have suggested that bottom trawling takes place over an area equivalent to half of the world’s continental shelf, even though members of the fishing industry have consistently asserted the impact is much more limited because of their targeted use of well-defined fishing grounds, rather than widespread “ploughing” of the seabed.

Importantly for South Africa, the study shows that in regions where the bottom trawling footprint is less than 10 percent of the seafloor area, fishing rates on bottom-dwelling fish stocks almost always meet international sustainability benchmarks. South Africa’s trawl footprint is very close to the 10% threshold and a “ring-fence initiative” ensures it will stay that way. The ring-fence initiative is a voluntary undertaking by members of the South African Deep-Sea Trawling Industry Association (SADSTIA) to only trawl on currently used grounds, prevent damage to lightly trawled areas and preserve natural refuges for hake. Trawling outside the ring-fenced area requires the completion of an environmental impact assessment.

“Despite the important contribution that trawling makes to global food security, it often gets a bad rap,” says Johann Augustyn, secretary of SADSTIA. “The study by Amoroso and his co-authors is important because it shows that trawling impacts a far smaller area of the seabed than was previously thought.”

Augustyn emphasised that the South African trawl fishery for hake is sustainable and well-managed, saying it is the only fishery in Africa to be certified by the Marine Stewardship Council, the world’s leading certification and eco-labelling programme for sustainable, wild-caught seafood.

“The Amoroso study is part of a larger effort known as the Trawling Best Practices Project,” he explained, “as an industry we are enthusiastically supporting this global initiative because ultimately it will publish a set of “best practices” for the methods, equipment, density and frequency of bottom trawling.”

Apply for a life-changing internship in the fishing industry

In September, SADSTIA announced that it would fund and support 10 internships in the field of fisheries management, aquaculture, environmental science and related fields.

Now, SADSTIA’s partner in the SADSTIA/DAFF/WWF Graduate Internship Programme, WWF, has called for interested students and graduates to apply for these exciting positions. Please follow this link to find out more.

The closing date for applications is 9 November 2018.

Fishing industry announces new opportunities for graduates

The companies active in South Africa’s deep-sea trawling industry have teamed up with the Department of Agriculture, Forestry and Fisheries (DAFF) and the conservation organisation WWF-South Africa to provide an opportunity for 11 new graduates to work in the field of fisheries management, aquaculture, environmental science and related fields.

The South African Deep-Sea Trawling Industry Association (SADSTIA) announced today it is to sponsor 11 paid and structured internships for the period 1 April 2019 to 31 March 2020. The internships will form part of WWF’s highly successful Graduate Internship Programme which aims to provide a practical bridging experience for new graduates to make a career in the field of environmental sciences.

As the only fishery in Africa to be certified as sustainable and well-managed by the Marine Stewardship Council – the world’s leading certification and eco-labelling programme for wild-caught seafood – SADSTIA already works closely with WWF on a range of fisheries improvement projects.

“Our members recognise that youth unemployment is one of the most serious challenges facing South Africa today and the SADSTIA/DAFF/WWF Internship Programme provides us with an opportunity to make a real difference and assist government,” said Terence Brown, chairman of SADSTIA. “We hope the programme will give individuals an opportunity to gain valuable work experience, link to professional networks and possibly establish a career in the fishing industry.”

Eight of the 11 SADSTIA/DAFF/WWF interns will be placed at fishing companies and three will be placed at the Fisheries Branch of the DAFF. The Fisheries Branch has a mandate to manage South Africa’s commercial, recreational and subsistence fisheries and it requires a range of skills – including biological and mathematical knowledge, analytical and managerial ability – to name just a few.

DAFF has played a key role in the establishment of the internship programme and representatives of the Department expressed their appreciation for the opportunity of working with SADSTIA and WWF to tackle the critical problem of youth unemployment. The Department believes the programme will not only provide opportunities and inspiration to to new graduates, but it will help to secure the skills necessary to manage sustainable fisheries into the future. It intends to use the internship programme to build a cohort of young professionals skilled in freshwater aquaculture information management, feed development and animal health and husbandry.

SADSTIA research assistant, Fisokuhle Mbatha, who joined SADSTIA as an intern in April 2017 and was appointed to a full-time position with the Association as soon as her internship was complete, also shared her perspectives at the launch of the SADSTIA/DAFF/WWF Internship Programme, saying:

“My internship was the ‘mobile starter-pack’ I needed to build my career. It connected my academic knowledge of fisheries to the real-life work environment. I was offered many opportunities to network with professionals with expertise in marine science and working alongside them has motivated me to be an internationally recognised marine scientist in future.”

Mbatha holds a Masters Degree in Applied Marine Science from the University of Cape Town.

WWF will call for applications from prospective interns in October. Details of the application procedure will be posted to the SADSTIA website following the public advertisement.

Representatives of SADSTIA, WWF and DAFF launched an internship programme in Cape Town in September. Pictured from left are, Johann Augustyn, secretary of SADSTIA; Madoda Khumalo, strategic services executive at Sea Harvest and head of SADSTIA’s Scientific Committee; Morné du Plessis, CEO of WWF-South Africa; Fisokuhle Mbatha, SADSTIA research assistant; Glenda Raven, director of the WWF Graduate Internship Programme; Belemani Semoli, acting director general of the Fisheries Branch of DAFF; Sue Middleton, chief director of Fisheries Operations Support in the Fisheries Branch of DAFF; Terence Brown, operations director of Sea Harvest and chairman of SADSTIA; and Saasa Pheeha, acting chief director of Fisheries Research & Development in the Fisheries Branch of DAFF.

Hake has a low environmental impact

South African hake comes from a sustainable and well-managed fishery. Now an international study has revealed another good reason for choosing hake over beef and many other forms of animal protein: hake has a low environmental impact.

According to the study − published this week in the journal Frontiers in Ecology and the Environment − industrial beef production and farmed catfish have the greatest impact on the environment, while small, wild-caught fish and farmed molluscs like oysters, mussels and scallops have the lowest environmental impact.

Hake, pollock and cod were named as wild-caught fish with a relatively low impact.

“What you eat makes a difference to the environment,” said Johann Augustyn, secretary of the South African Deep-Sea Trawling Industry Association. “South Africans are fortunate because locally caught hake is sustainable, affordable and versatile and we now know that it compares very favourably to other animal proteins when it comes to the environmental impact of its production.”

The environmental cost of animal source foods is authored by United States researchers Ray Hilborn, Jeannette Banobi, Stephen Hall, Teresa Pucylowski and Timothy Walsworth. They believe their study to be the most comprehensive analysis of the environmental impacts of different types of animal protein production.

The study uses four measures as a way to compare environmental impacts across a number of different types of animal food production, including farm-raised seafood (aquaculture), livestock farming and seafood caught in the wild. The four measures are: energy use, greenhouse gas emissions, potential to contribute excess nutrients – such as fertilizer – to the environment, and the potential to emit substances that contribute to acid rain.

In order to make their comparisons, the researchers used a standard 40 grams of protein –the size of an average hamburger patty and the daily recommended protein serving – and calculated, for example, how much greenhouse gas was produced per 40 grams of protein across all food types, where data were available.

Their analysis revealed animal protein types that had low environmental impacts across all measures. These include farmed shellfish and molluscs, and capture fisheries such as sardines, mackerel and herring. Other capture fish choices with relatively low impact are whitefish like pollock, hake and the cod family. Farmed salmon also performed well.

The researchers found that, when compared to studies of vegetarian and vegan diets, a selective diet of aquaculture and wild capture fisheries has a lower environmental impact than either of the plant-based diets. Mollusc aquaculture – such as oysters, mussels and scallops – actually absorb excess nutrients that are harmful to ecosystems. Capture fisheries consistently scored better than aquaculture or livestock production because no fertilizer is used.

For capture fisheries, fuel used to power fishing vessels is the biggest environmental impact. However, the impact of trawling appears to be related to the abundance of fish; healthy stocks take less fuel to capture.

“The South African trawl fishery for hake has been certified as sustainable and well managed by the Marine Stewardship Council (MSC) since 2004,” said Augustyn. “The MSC is the gold standard of eco-labelling programs for wild-caught fish. On the strength of this latest study, we can confidently say that South African hake is a good environmental choice.”

International experts lend scholarly weight to the trawl fishery’s management

The process of reviewing the Operational Management Procedure (OMP) used to manage the South African hake fishery is underway and a panel of international experts has contributed a number of recommendations that will strengthen and improve the review.

The experts – Sean Cox of Canada, Malcolm Haddon of Australia, Daniel Howell of Norway and Andre Punt of the United States – are acknowledged experts in the fields of quantitative fishery science, stock assessment, ecosystem modelling and statistical analysis of data. They led discussion at the International Fisheries Stock Assessment Review Workshop at the University of Cape Town (UCT) late last year. The annual workshop, which is convened by Emeritus Professor Doug Butterworth, head of the Marine Resource Assessment and Management (MARAM) Group at UCT’s Department of Mathematics and Applied Mathematics, is funded by the Department of Agriculture, Forestry and Fisheries (DAFF). It performs a peer review function by providing local fisheries scientists with an opportunity to subject their stock assessment techniques and findings to the scrutiny of international experts in the field.

This year’s workshop focused on the assessment and management of hake, sardine and rock lobster, which are among South Africa’s most valuable fisheries. When considering the management of the hake fishery, the experts made a number of suggestions pertinent to the review of the OMP that is used to manage the fishery.

OMPs are used to manage most of South Africa’s major commercial fisheries. They utilise pre-determined sets of information – such as industry catch records and the results of annual research surveys – and apply a set of pre-determined harvest control rules to recommend an annual total allowable catch (TAC). They are generally revised every three to five years so that they may accommodate changing fishing practices and new knowledge about the behaviour or composition of fish stocks.

The OMP currently used for the South African hake fishery is known as OMP-14 because it was adopted by the Demersal Scientific Working Group of the DAFF in 2014 and has been used to set TACs for all the hake fisheries, including hake deep-sea trawl and hake inshore trawl fisheries. It is currently under review and will be implemented in time to recommend the TACs for the 2019 fishing season.

“The South African trawl fishery for hake is acknowledged as one of the best managed hake fisheries in the world,” said SADSTIA Secretary, Dr Johann Augustyn.

“We welcome the technical expertise and input of the international panel of experts and we are confident that the process of updating the OMP and adopting OMP-18 will further refine the management of the hake fishery.”

The South African hake fishery has been certified as sustainable and well-managed by the Marine Stewardship Council since 2004. It is the only fishery in Africa to have achieved such recognition. The MSC conducts annual surveillance audits of the fishery and is expected to embark on re-assessment of the fishery for a further five years in 2019.

  • The International Review Panel Report for the 2017 International Fisheries Stock Assessment Workshop is available here (technical document).
  • A non-technical summary (PowerPoint presentation) is available here.

Ellen Khuzwayo survey to quantify the impacts of trawling

The South African research vessel Ellen Khuzwayo departed on Monday 22 January from Cape Town on the fifth and final leg of an innovative five-year experiment that is expected to shed light on the contentious subject of trawling and the impact it has on the seabed.

Although bottom trawlers catch at least 20% of global marine fish catches and play an essential role in food security, trawling has been likened to “ploughing the sea floor” and criticised for inflicting irreversible damage on benthic (seabed) ecosystems.

The surveys conducted from the deck of Ellen Khuzwayo over the past five years are expected to provide a scientific view on this issue, particularly as it relates to the South African deep-sea trawling industry, South Africa’s most important commercial fishery.

Deep-sea trawlers target hake on trawl grounds that extend from the Namibian border on the west coast to the extreme eastern part of the Agulhas Bank near Port Elizabeth. Fishing takes place at depths of between 200 and 800m and it is estimated that trawling occurs in an area equivalent to 4.4% of South Africa’s exclusive economic zone.

The regularly trawled grounds of “Karbonkel”, located off the coast of the Northern Cape, with an average depth of 400m, were selected for the five-year “Benthic Trawl Experiment” (BTE) which is being implemented collaboratively by a number of partners, including the South African Deep Sea Trawling Industry Association (SADSTIA); the Department of Agriculture, Forestry and Fisheries (DAFF) – which provides the research platform Ellen Khuzwayo; the University of Cape Town (UCT); the South African Environmental Observation Network (SAEON) and the National Biodiversity Institute (SANBI).

As chief scientist on the Ellen Khuzwayo, associate professor Colin Attwood of UCT explains that for the purposes of the BTE, the Karbonkel grounds were divided into five clearly defined trawl lanes:

“In the first year, trawlers were able to trawl the entire area, but in subsequent years they were only allowed to trawl in the second and fourth lane. We’re trying to find out if the sea life in the first, third and fifth lane has recovered, using the life in the second and fourth lane as a comparison.”

The researchers are using a sophisticated underwater camera to collect images of the seabed, and at pre-determined locations the crew of the Ellen Khuzwayo has deployed a simple underwater grab that has collected samples of the animals living on or in seabed sediments. A curious collection of crabs, anemones, urchins, brittle stars and worms has been extracted from the sediments of Karbonkel.

“We’re looking at the emergent macrofauna – the big animals that stick out of the sediment, like sea anemones, sea pens, that type of thing, and then there are the animals that live in the sediment itself, like heart urchins and crabs. We’re also looking at the structure of the sediment to see if it is being influenced in any way by repeated trawling,” explained Attwood.

As soon as the Ellen Khuzwayo returns to Cape Town, an intensive analysis of five years of data will begin and the team expects that in two to three months time it will have the information it needs to definitively say, for the first time, what the impacts of trawling are in South Africa.

“The outcome of the experiment is expected to address critical gaps in knowledge of the long-term effects of trawling and the capacity of deep-sea habitats to recover from such impacts,” said Dr Johann Augustyn, secretary of SADSTIA.

Although the BTE is the first experiment of its kind in South Africa, similar experiments have been conducted in other parts of the world and SADSTIA has participated in a ground-breaking international initiative to determine the global impacts of trawling. This study was conducted by a team of 16 researchers who analysed data from trawl fisheries around the globe. They published their results in Proceedings of the National Academy of Sciences in July last year and determined that the impacts of trawling are highly variable; recovery times for plants and animals disturbed by trawling depend on the type of gear used and a range of environmental variables.

The South African trawl fishery for hake is certified as sustainable by the Marine Stewardship Council (MSC) the world’s leading certification and eco-labelling programme for sustainable, wild-caught seafood. Improving knowledge and understanding of the impacts of trawling on the benthic environment is one of the conditions of MSC certification.