All posts by Duncan

What future for wild sea bass?

There are many things that can cause problems for a species. Sometimes it’s some aspect of the biology that makes them vulnerable. Sometimes it’s human pressures. And sometimes it all comes together to really cause problems for an animal. Sea bass are a popular fish for commercial fishermen and anglers, and are a popular fish for eating. Despite the fact that most of the sea bass consumed in the EU is farmed wild sea bass populations are in trouble. While assessments of the stock are not easy, ICES, the intergovernmental organisation that gives advice on sustainable fishing to the EU has said that the losses from the population due to fishing have consistently been above sustainable levels1 and also recruitment of young fish has been very poor since 20081.

Swimming Sea Bass
Sea Bass by Bjoertvedt is licensed under creative commons (CC-BY-SA 4.0)

Sea bass grow slowly and mature relatively late. They mature between four and seven years old when the males are around 35 cm long and the females are around 42 cm2. Before the 1st September 2015 the minimum size for landing was 36cm nationally2, although some regions such as Cornwall had a slightly larger size3. Not surprisingly, having a minimum size where the female fish could be landed before they had had a chance to breed is not the best route to a sustainable fishery. Sea bass behaviour also increases their vulnerability to over-exploitation. The juveniles congregate in groups in estuaries, and as adults migrate offshore to spawn (where they are targeted by trawlers4) and then return to the same coastal sites year after year5. This site fidelity means that once local populations are overfished recovery is slow, especially if there are cold winters that can kill juveniles, reducing the number of new individuals recruited to the population5. All these factors mean that the breeding population has dropped from around 16,000 tonnes in 2009 to less than 7,000 tonnes in 2015. ICES state that the ability of the population to reproduce successfully is seriously compromised below 5,000 tonnes.

So what has been the response? The minimum landing size has been increased to 42cm6 and is now called the minimum conservation reference size, which at least gives the females a chance to breed but comes at a cost for the fishermen. The fish that are above 35cm now and could have been caught under the old rules are now not available to be caught until they grow large enough to exceed the new minimum. There is also to be a closed season for six months of the year between January and June to allow the fish to spawn. For the other six months of the year recreational anglers will be allowed to land one bass per day, while commercial fishers are restricted to catch limits of one tonne per month. The EU proposes that catch limits should fall from 2,656 tonnes in 2015 to 1,449 tonnes in 2016, a reduction of around 45%7. The problem is, though, that ICES has said that the limit should be set at 541 tonnes for 20168, which would be a reduction of 80% on the 2015 figures. In other words, the limit set by the EU is nearly three times larger than what the scientific assessment says it should be. This may be an attempt to spread the impact on fishermen over a longer period, but with the stock at such a low level this may backfire. A collapsed fishery supports no one.

What else could be done? Save Our Sea Bass suggest that the lower landings limit (the ICES figure) should be adopted as a matter of urgency, and that both anglers and commercial fishermen should only be allowed to catch sea bass by rod and line or hand lines. They also suggest that the share in the 541 tonnes should be distributed in line with article 17 of the common fisheries policy, which means based on environmental criteria and economic benefits to coastal communities. The idea behind using lines to catch sea bass is that line-caught sea bass fetches higher prices. The marine conservation society has a good fish guide, and currently (November 2015) lists wild-caught sea bass as a fish to avoid. Farmed sea bass are a more acceptable alternative to wild-caught fish.

You can keep up to date with sea bass issues either from the Marine Conservation Society or Save Our Sea Bass site.

References

1,8 ICES Advice on fishing opportunities, catch, and effort Celtic Seas and Greater North Sea Ecoregions 2015
2 European sea bass (Dicentrarchus labrax) exploited around Welsh waters – preliminary results: December 2013.
3Cornwall Inshore Fishery and Conservation Association new minimum size for bass
4Protecting Sea Bass
5Parliamentary briefing on sea bass.
6Bass fishing: catch limits, minimum size, and where you can fish (Gov.uk)
7Commission proposes fishing opportunities in the Atlantic and North Sea for 2016

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Losing the plural

There’s been a slight change of name from ‘Our Common Oceans’ to ‘Our Common Ocean’. So why the change? Well, I went to the EMSEA 15 conference early in October and one of the first people I spoke to was Peter Tuddenham of the College of Exploration, who quickly spotted the ‘mistake’ on my name badge and argued that it should be ‘ocean’ rather than ‘oceans’. It makes sense. After all, looking at the thermohaline circulation shows the connections clearly.

Map of the thermohaline circulation of the oceans
Thermohaline Circulation

Plus, it’s the first of the ocean literacy principles: The Earth has one ocean, with many features. So goodbye oceans, hello ocean.

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No limits, no future

Recently, I volunteered with the Shark’s Trust at the Dive Show in Birmingham helping to raise awareness about their ‘no limits no future‘ campaign to stop uncontrolled shark fishing. Shark and ray populations worldwide are under increasing pressure, and the total number of sharks caught annually may be over 100 million. One study1 published earlier this year (2014) estimated that up to a quarter of shark and ray species are threatened if assessed using the IUCN red list criteria. If we think about risks to shark populations we might think about shark finning in the Pacific, or sharks being caught as part of longline fisheries for tuna2 but the problem is actually a lot closer to home.

Originally, sharks were an unwanted part of the catch (bycatch) as fishermen pursued species such as cod and tuna, but now there is an increasing trend for the targeting and retention of these bycatch sharks. They are caught for their meat, their fins and their liver oil. Unfortunately, the life-history and behaviour of sharks makes them vulnerable to overfishing and populations are declining. Sharks reach maturity late and have relatively few young compared to other fish. In addition, they often congregate in groups of individuals that are either all a single sex, or are very close in age. Should a fisherman catch these sharks it has a bigger effect than catching the same number of sharks at random from the population.

In 2012 there were 280,000 tonnes of reported shark landings worldwide, with EU vessels landing 40% of this world total, the majority of which came from the Atlantic ocean and Mediterranean sea. One issue in that this is reported landings – the true level of landings is thought to be three to four times higher3. Worse still, most of this European catch from the Atlantic and Mediterranean is concentrated on just five species4.

These five species are:

97% of all sharks caught and landed from the Atlantic and Mediterranean in 2012 are no limits species, which has been estimated to amount to 6,400,000 individuals. This is why although some of the species above are currently listed as of ‘least concern’ it’s important to make the fisheries sustainable before the populations crash due to overfishing. Once overfished, there is no guarantee that populations will recover as demonstrated by the collapse of the cod fishery on the grand banks off the eastern coast of Canada. In addition, sharks are important components of ecosystems as top-level predators. The shark trust is campaigning for science-based catch limits. Please sign the petition, and see the ‘get involved‘ page for other ways to contribute.

References

1http://elifesciences.org/content/3/e00590
2http://www.sciencedirect.com/science/article/pii/S2351989414000055
3 4http://www.nolimitsnofuture.org/wp-content/uploads/2014/07/no_limits.pdf

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