Thirty years after the widely publicised decline and commercial extinction of northern cod off the northeast coast of Canada, the average abundance of groundfish stocks, including the Cape hakes, is increasing and may result in increased harvests in the future.
The paper Global status of groundfish stocks which was published in the journal Fish and Fisheries earlier this year, attributes the change in the status of groundfish stocks around the world to reduced fishing pressure and strengthened fisheries management.
“Groundfish” is an umbrella term like “demersal fish” which is given to fishes that live and breed on or near the bottom of seas or lakes. Groundfish are found in the temperate and higher latitudes of both the Northern and Southern hemispheres, but stocks in the Northern hemisphere tend to be much larger. Pollock and cod are by far the most abundant species of groundfish, but the term includes other species like hake, haddock and rock fishes. According to the Food and Agriculture Organization of the United Nations, annual groundfish landings have averaged 10.5 million metric tons since 2000.
South Africa and Namibia’s catch of Cape hakes makes up a tiny portion of the global catch of groundfish (about 300 000 tons per year), but the two countries’ fishing grounds in the southeast Atlantic Ocean are identified in the paper Global status of groundfish stocks as one of five regions where fishing pressure is low and stocks might potentially sustain a higher catch. However, the authors of the paper note there are at least three good reasons why fisheries managers may choose to manage stocks conservatively and forgo some potential yield. The first reason is that target stocks are often caught together with other species of fish and it is not possible to achieve optimum yields for all species. Secondly, when fishing pressure is lower than maximum sustainable yield, it is economically more efficient to catch fish, and thirdly, there is a recognition that the needs of other marine animals that forage on fish species must be considered.
Interestingly, the certification of the South African trawl fishery for hake and the Namibian trawl and longline fisheries for hake by the Marine Stewardship Council (MSC) is not unusual for groundfish fisheries. In fact, the majority of large groundfish stocks in Europe, New Zealand, Russia, South Africa, Namibia and the United States of America are certified sustainable by the MSC. This indicates the stocks are healthy and well managed, say the authors of the paper.
The advent of seafood certification and labelling schemes and the major expansion of marine conservation efforts by environmental NGOs may be one of the reasons why the downward trend in the status of groundfish stocks was reversed after 1990, say the authors of the paper:
“With the increasing concern about overfishing in the 1990s, we saw management intensity continue to increase, fishing pressure decline and stocks stop their decline and start to rebuild.”
Whereas groundfish stocks around the world have been rebuilt since the 1990s, the one exception is the Northwest Atlantic (Canada and the United States) where stocks have not rebuilt to levels approaching their targets, even after fishing pressure was dramatically reduced. The authors attribute the slow recovery of these stocks to changes in productivity that took place in the late 1980s and early 1990s.
They acknowledge that there can be differences across fisheries regions and in some cases, when the average stock status is above target biomass and fishing pressure is below target, some stocks may be at low biomass or subject to excess fishing pressure. Similarly, they note that fishing is not the only variable that influences groundfish stocks – they are subject to environmental changes that may be heightened by climate change.
The authors conclude that if fishing for groundfish species could be more selective and the incidental catch of non-target species could be reduced, there is potential for groundfish to be exploited at or near their most productive levels, resulting in a bigger harvest of fish for human health.
Read the paper: https: https://onlinelibrary.wiley.com/doi/epdf/10.1111/faf.12560