Study finds sea lice not a significant factor in decline of wild salmon
A nine-year investigation by the Marine Institute into the possible causes of the steep decline in the survival rate of Atlantic salmon at sea concludes that sea lice infestation plays a relatively minor role – accounting for only 1% of overall marine mortality rate in the stocks studied, or ten fish in a thousand.
Inland Fisheries Ireland, another State agency, but charged with responsibility for the protection, management and conservation of inland fisheries and sea angling resources however says that this 1% “maybe the crucial tipping point”.
Donal Maguire, Aquaculture Development Manager with BIM, speaking at the public meeting and debate on the proposed Galway Bay Salmon Farm held at the Nuns Island Theatre, Galway. Photo Joe O’Shaughnessy, courtesy of The Connacht Tribune
Dr David Jackson who manages the Marine Institute’s Aquaculture Section and is in charge of the National Sea lice Monitoring and Control Programme confirmed to Inshore Ireland that the study, which involved over 350,000 migrating salmon from twenty-eight releases at eight locations on Ireland’s south and west coasts between 2001 and 2009, “provides clear evidence that while sea lice-induced mortality on outwardly migrating smolts can be significant, it is a minor and irregular component of marine mortality in the stocks studied and is unlikely to be a significant factor influencing conservation status of salmon stocks”.
Reason unclear
He added that while the cause for the alarming declining trend in sea survival of wild Atlantic salmon “remains unclear” it was likely to be due to a variety of different factors.
“The list of possible causes is long and could be due to a combination of these. Global warming; changes in locations or availability of prey species associated with the North Atlantic oscillation; increased fishing pressure and predation; habitat changes and the loss of post-smolts as by-catch in pelagic fisheries; sea lice infestation and sea lice-induced mortality have all been suggested. However, the results of a thorough analysis of the combined data over nine years suggests that sea lice are unlikely to be a significant factor,” he declared.
Standing firmly behind his findings, Jackson believes it is very important to realise that his team’s conclusions are based “on large samples of fish” ― and over a significant time period.
“We’ve been looking at sea lice on wild salmon for a number of decades now, and have published half-a-dozen scientific papers on our research. We’ve found that lice-induced mortality to be, on average, around 1% while over the same period the average mortality in smolts is over 90%. Also, that level of mortality wasn’t found in all samples. In fact, it was only about 40% of samples where there was a significant level of mortality that could be attributed to sea lice.”
Research leaders
He added that Ireland is to the forefront of salmon lice research and has been taking the whole issue of possible lice infestation of samonids – sea trout and salmon “very seriously indeed”.
“We’ve a very robust monitoring and control programme in place in Ireland that targets controlling lice levels on salmon during the Spring months when salmon and sea trout migrate. The programme has been in place since the mid-1990s and has been very successful.
“By controlling lice at that time of year you manage to achieve two goals: as a precaution you ensure there isn’t a large reservoir of lice to infect wild fish, and it’s also the best time to target lice to ensure optimum control on farms and to minimise the need to use treatments to control lice”.
Similar results
Jackson says his findings are “very much in line” with those from a similar study by Norwegian fisheries biologists who have come to the same conclusions:
“The results of a major study over twelve years in Trondheim Fjord published in 2007 found that lice-related mortality to be between 1-2%. As well as that, a more recent study from that country involving more than 100,000 fish also shows results very similar to ours.
“Putting this in context, these Norwegian studies – along with our own – have produced data which is based on more than half-a-million fish. And while they employed slightly different methodologies, the results all point to the same answer.”
As for the salmon louse itself, Jackson says it is “a very versatile parasite and will be virtually impossible to eradicate”.
“Salmon lice are very widely distributed around the globe. They are found in the Pacific and the Atlantic, so we’re going to have to live with that fact. From the very beginning of salmon farming, sea lice have been an issue in the same way that liver fluke are an issue for sheep and cattle farmers in terrestrial farming. And just like they have developed ever-improving methods to control fluke parasites, we’re going to have to learn to manage lice in salmon farming”.
Looking to the future, Jackson believes the answer is likely to be the development of an effective anti-lice vaccine; however he feels that this is unlikely to happen in the very near future.
“An effective vaccine would be the Holy Grail but as that’s probably still a long way off we must develop the best possible integrated management processes that we can.”
Fish farm licence
Meanwhile, BIM has moved quickly to quell concerns that its proposal for a large deep water salmon farm near Inis Oirr in Galway Bay might be a reservoir for salmon lice and in turn impact seriously on wild salmonid stocks.
Acknowledging that the Galway proposal has sparked “some concerns and anxieties” especially regarding sea lice, BIM’s chief executive Jason Whooley says that “while real, these fears are unfounded”.
“Some concerns and anxieties have been expressed in relation to this project, particularly by bodies representing sea and inshore anglers. These centre on the impact such a large project could have on the marine environment and on stocks of wild salmon and sea trout.
“In particular, concern centres on the impact of a potential transfer of sea lice from farmed fish to the wild fish. In terms of the marine environment, the exposed nature of the proposed site and high levels of water exchange ensure there will be little or no buildup of wastes.”
And pointing to the Marine Institute study, Whooley says it confirms that salmon farming was having no negative effect on wild salmon:
“Despite this, government has adopted a ‘precautionary approach’ to dealing with sea lice on salmon farms by imposing strict controls on the Irish industry”.
“The effectiveness of the National Sea lice Monitoring and Control Programme has resulted in the European Commission recently confirming that Ireland’s sea lice control system is the best in the world. Notwithstanding, and in order to ensure the highest levels of environmental and operational compliance, BIM intends to act as the licence holder and not the operator of this site,” he explained.
“If our application for this licence is successful, we will apply additional standards to the running of the Inis Oírr salmon farm that exceed existing environmental and safety regulations. This approach will also maximise returns to the local economy in accordance with our mission to develop the Irish seafood industry”.
+++++++++++++++++++++++++++++++++++
DEFINING MOMENT HAS COME IN SALMON FARM FIGHT
Noel Carr, FISSTA
There are many in the wild salmon and sea trout fishery sector who regard this new plan and strategy by Marine Minister Simon Coveney as the final nail in the coffin of what was a sustainable resource that will be wiped out within a few seasons.
But there is no doubt that the international trade press and aquaculture industry are excited by what they deem to be a most creative initiative to fast-forward the production figures of farmed salmon from 14,000 to 150,000 tonnes to feed the massive projected market demand as announced by BIM in their EIS application.
Political capital
The target to grow production tenfold on just ten sites proves that this minister is convinced that the plan is viable and is prepared to invest a huge portion our money and his political capital into a project that has already branded him as a pioneer by the industry.
The reason he gets the pioneering tag is because of the new way the ten applications are being processed. No longer does IFA Aquaculture have to assist their members with applying and risk their time and money to comply with the regulations.
Minister Coveney has decided to use our State’s time and money instead and then lease the sites to producers to run them in compliance with the best practice standards as laid out in the appropriate Environmental Impact Statement.
This may sound feasible, but when one considers the history of how the industry has been managed, for example in Co Donegal’s Mulroy Bay, we will have very serious problems.
Rising temperatures
The case study of Mulroy Bay proves that the Summer water temperatures there and even further north in Scotland are too warm for salmon farming – causing Amoebic Gill Disease and resulting in the closure of most sites for long fallowing periods of recovery.
So, will the water temperature in Galway Bay be colder than poor–flushing loughs like Mulroy, Swilly or Glenarm? No. It will be warmer, as will the waters of Clare, Shannon and Kerry where more salmon farm locations are planned.
From a fish farming point of view, it appears the Minister is clearing a barren field to plant seed that can never be harvested unless we get a freak very cold spell for two consecutive Summers to keep the temperature below the target level. Sadly, the gamble is all the more surprising as it is State money that is being used to bankroll the risk at a time when no more such foolhardy risks can be afforded.
Dáil mention
Pioneers of the Wild West were the ones with the arrows in their backs, and so it could be for Minister Coveney as it appears that not everyone in Government knows what his real plans are at this crucial stage of the Galway Bay application process. Most Oireachtas members are not up to speed on this plan, and neither is An Taoiseach, Enda Kenny who stated in the Dáil on December 19:
“We must have a debate and an understanding that the level of production is an issue ….An application lodged for a major fish farm development off the Aran Islands …is being heavily objected to, with another possibly to follow off the west coast. This is an issue that needs to be debated here, by the planning authorities and by those dealing with environmental regulations.”
It is a bit late for a Dáil debate after BIM has been voted to spend millions in the budget to progress the plan. Minister Coveney does not want to hear of any debate lest the whole idea be held up to scrutiny for all to be exposed.
So, the coming weeks will signal some very significant decisions on the future of our wild fish should the Minister decide to issue a licence to put salmon cages in Galway Bay.
There is no doubt that the defining moment for our wild salmon and sea trout fisheries is now. Because the magnitude of the 150,000 tonnes, ten project plan, means that it is a choice between the jewels such as Galway Bay for tourism or face a future where fish farm pollution and tourism job losses will wipe out all the hope and dreams of future generations.
+++++++++++++++++++++++++++++++++++
STATEMENT FROM INLAND FISHERIES IRELAND
Wild salmon survival in the balance – 1% may be the crucial tipping point
Inland Fisheries Ireland (IFI) notes the recent Marine Institute (MI) publication which identifies that sea lice emanating from aquaculture facilities can cause mortality to wild Atlantic salmon. In this regard, the recent publication (Jackson et al, 2012) concurs with previously published international research (Krkosek et al, 2012 & Gargan et al, 2012).
IFI welcomes the fact that there is now a clear acceptance of the negative impact of sea lice on juvenile salmon and the debate can now progress to identify the best methodologies to reduce or eliminate this impact. IFI would also like to see similar progress in relation to the issue of escaped farmed salmon.
In recent years approximately 5% of all juvenile salmon going to sea return back to their native rivers as adults to spawn. Precisely because natural mortality rates of salmon are high, even a proportionally small additional mortality from sea lice can amount to a large loss in salmon returning.
To put this average 1% reduction in return rates, as reported by the MI, in context, if 3,000 salmon return to a river, and this represents a 5% return rate, a reduction in the return rate to 4% translates into a reduction of 1/5 (20%) of the adult salmon or 600 fewer fish returning. The Board of IFI is concerned that this level of additional mortality has the potential to curtail commercial or recreational salmon fisheries and impact on individual river salmon conservation limits and may be the tipping point between having an open or closed fishery.
The paper identified that just under 40% of released juvenile salmon showed a significant difference in return rate between sea lice ‘treated’ and ‘non-treated’ groups, indicating that mortality from sea lice is significant in 40% of the releases in the study. Unfortunately, there was a significant effect from sea lice in six different bays along the west coast over the study period.
This recent study provides further evidence that salmon will be impacted by sea lice. The location of salmon farms in relation to salmon rivers and the control of sea lice prior to and during juveniles salmon migration to their high seas feeding ground is critical if wild salmon stocks are not to be impacted. The development of resistance to chemical treatment of sea lice and other fish husbandry problems, such as pancreas disease and amoebic gill disease, are likely to make effective sea lice control even more difficult in future years.
Norway, one of the world’s biggest producers of farmed salmon are also seriously concerned about the impact of sea lice emanating from aquaculture facilities on wild salmon stocks and the issue of escaped farmed salmon. In their Strategy for an ‘Environmentally Sustainable Norwegian Aquaculture Industry’ produced by the Norwegian Ministry of Fisheries and Coastal Affairs they state:
“Even though salmon lice occurs in wild salmon and sea trout, it is an example of a parasitic disease which has been intensified by the multitude of hosts in aquaculture facilities. In addition to being passed from fish to fish, it can also be spread over long distances by currents”
They further state;
If delousing in fish farming fails to yield the desired effect on lice figures for wild fish, it may be necessary to consider a reduction in the biomass of the farming facilities (reduce the number of hosts) in the worst-affected areas.”
On the matter of escaped farm salmon, the Norwegian authorities have stated that “scientific comparisons of wild and farmed salmon, and their cross-breeds, has shown that gene transfer from farmed to wild salmon can reduce the latter’s ability to survive. This is why such gene transfer is one of the main problems with escapes”. IFI would like to see similar progress made on the issue of escaped farmed salmon as has been made on the sea lice issue.
IFI are supportive of the development of a sustainable aquaculture industry and welcome all advances in research that will underpin the sustainability of this industry and safeguard wild salmon and sea trout stocks into the future.
Recommendations to address the issues of sea lice, escapes, location and scale have been made in IFIs submission to the Department of Agriculture, Food and the Marine on the Environmental Impact Statement regarding the Galway Bay fish farm development.
