Thousands of dead fish were found floating in the water along the Kwun Tong promenade over the weekend (11-7-12/7/2015), releasing a strong stench that many passersby found unbearable.
The dead fish covered a two-kilometer stretch along the promenade, and it took the Marine Department seven hours to clean up about 2,000 kilos, Apple Daily reported.
Several species were identified, including tilapia, seabream, grey mullet and spotted silver scat.
Cheung Ma-shan, science manager at the Eco-Education and Resources Center, said the mass death could be due to the low oxygen content in the water caused by typhoon Linfa.
Chong Dee-hwa from the Ichthyological Society of Hong Kong said the typhoon could have stirred up mud and toxins from the bottom of the sea, thus affecting fish populations.
The Department of Environmental Protection was undertaking tests of water samples obtained in the vicinity.
More than 25 local marine biologists have been awarded a grant that will enable them to study the marine biodiversity and ecology of the Tolo Harbour and channel.
Tolo Harbor is a semi-enclosed body of water in the northeast of Hong Kong linked to the sea only by the narrow Tolo Channel. The Tolo Channel and Harbor were infamous in the 1980’s for terrible water pollution, fould smells and red tides. A rapid expansion of urban areas on the firnge of Tolo Harbor with direct, untreated sewage discharges into the Harbor caused large scale eutrophication. The sewage outfalls provided nutrients feeding massive algal blooms which subsequently died and their decomposition by microorganisms used up so much oxygen that the water and sediment became anoxic, killing fish and many other marine organism (again feeding oxygen demand form decomposition) and causing foul smelling water. The problem was made much worse because Tolo Harbor is not very well flushed with new oxygenated water from the sea. It was eventually improved by providing proper modern sewage treatment and recognizing the particular vulnerablility of the area to eutrophication.
The HK$4.3 million will benefit the Joint University Consortium for Biodiversity, Ecology and Conservation of Marine Ecosystems and comes via the Environment and Conservation Fund (ECF). The ECF was established by the government in 1994 as part of its long-term commitment to environmental protection and conservation and received an injection of $5 billion in 2013, to serve as seed money generating an annual investment returns to support green projects and activities. The ECF has so far funded over 4,290 educational, research, and other projects and activities in relation to environmental and conservation matters.
Despite the funding being delayed for about two years, the proposal was approved last month and the 18-month project will commence later this year. The first stage of the two-phase study is aimed at finding the current ecological status of the area as well as the economic value of marine resources. The team will establish a comprehensive species database of the area. Kevin Ho King-yan, a senior research assistant at the School of Biological Sciences at the University of Hong Kong, said the proposal was aired at least two rounds of interviews, possibly because of the large amount of money required.
More than 280 participants from 26 countries have come together for the four-day conference to discuss issues such as coastal development and marine conservation. More than 20 marine scientists from overseas and the mainland are attending. Organizing committee chairman Kenneth Leung Mei-yee said experts from across the globe need to work together to map out a plan to protect marine biodiversity. “We need experts from all different sectors to join hands together to uncover what we have and how we can protect them and how we can make sustainable use of these resources,” Leung said.
This week I spotted the largest school of fish I have ever seen in Hong Kong. The grey mullets (Mugil cephalus) were attracted to a submarine seawater cooling outflow pipe that was discharging a grey liquid into the sea in western Kowloon. Each of the fish in the video below is 30-50 cm in length and I estimate there were at least 1000 of them.
I often see large mullets in that area. They regularly leap several feet into the air which is quite a spectacular sight. I have also seen an old angler at the Central ferry piers catching a 40cm mullet to the raucous applause of about 30 onlookers. The thing is the fish wasn’t hooked through the mouth but through the fin (quite a skill!) because it was swimming at the surface gasping and dying…
The behaviour of leaping out of the water according to some sources is a method mullets use to get more oxygen by storing air in their bodies so they can dive down into anoxic or low-oxygen water layers to catch prey others can’t. Grey mullets are known to be hypoxia-tolerant meaning they can tolerate low-oxygen environments better than other fish.
And here is another video of a large mullet just meters from Discovery Bay beach. The way it is gasping at the surface while swimming in its side is just how the fish was behaving which I saw caught at Central ferry pier.
So what does it mean if there is a large aggregation of fish which are known to be tolerant of low-oxygen environments and which are exhibiting low-oxygen behaviour? It’s a pretty good sign of a lack of oxygen – duh! What causes low oxygen in the sea? Nearly always eutrophication – the process whereby excess nutrients from normally man-made sources cause microscopic algae known as phytoplankton to grow into large blooms (and sometimes red tides). When these inevitably die off the mass of dead material on the seabed decomposes using up oxygen until there is so little that the seabed and lower depths become so-called dead zones (anoxic zone) where very few hardy species can survive.
So I suspected illegal waste-water discharge and made a report to the EPD (Environmental Protection Department) online including the above video (you can also report pollution via the government telephone hotline 1823).
Say what you want about the HK government, the civil service works! They followed up with a site visit to test the water and issued an order to the building management to repair their outflow pipe. Apparently the pipe was seawater cooling air conditioning outflow, but was discharging wastewater as well. Two days later after the problem was fixed and the fish were gone!
(Note: grey mullet is a very popular food fish in southern China and you will see it even in most supermarkets. But the vast majority is farmed – in case you were worried about your fish being from sewage outfalls!)
So what have HATS got to do with it?
HATS stands for the Harbour Area Treatment Scheme, a large sewage and wastewater treatment scheme designed to clean up HK’s notoriously filthy harbour. Setup in 2 phases, the first phase was successful enough to reduce the concentration of sewage to levels acceptable enough to allow the return of the New Year’s Cross Harbour Swim event. The annual event sees swimmers cross 1.89km from Lei Yu Mun’s Sam Ka Tsuen pier to Quarry Bay Park pier. First held in 1911 the event was stopped in 1978 because of health concerns.
However, in 2011 the EPD announced that water quality in the harbor, particularly in the eastern section where the race took place, had “shown significant improvement” and E. coli levels had decreased by 95 percent since 2001. Yet, the data from the EPD Shortly before the restarted race revealed that E. coli levels in the harbor were still twice the maximum acceptable level at Hong Kong bathing beaches. But it was still a big improvement.
The sewage levels are evaluated by measuring the concentration of the common gut bacteria Escheria coli(E. coli) in the samples as a proxy for all the other gut inhabiting and potentially dangerous bacteria and viruses in sewage.
However,the planned second phase of Hong Kong’s Harbour Area Treatment Scheme (HATS) has recently been put on indefinite hold. The upgrade would have boosted the capacity of the treatment works to remove nutrients such as phosphates from effluent. This would have reduce eutrophication and helped rehabilitate the dead zones. Excess phosphates are also linked to increases of toxic algal blooms.
Officials said the current chemical-based treatment system was enough to meet most water quality objectives and stressed the upgrade to biological treatment was not “critical” at this stage. The planned upgrade would deliver “only marginal improvements” to water quality in western Victoria Harbour and bring little benefit to near-shore pollution. Their priority was to cut off improperly connected pipes and crack down on unlawful discharges into the harbour off Central and Wan Chai.
When I first read that I was highly sceptical and thought the government was just trying to save money. But having seen illegal discharge from a major shopping mall and office complex directly into the Harbour I now think they actually have a very good point!
Denying the scheme was declared dead, assistant director of environmental protection Amy Yuen Wai-yin said that in terms of E coli levels close to the harbour’s shores, the upgrade was “not an answer”, citing water quality modelling results. The cost of the upgrade, according to the latest estimate based on 2012 prices, has almost tripled from the 2004 estimate of HK$11 billion to up to HK$30 billion. Perhaps then they are right to concentrate on cleaning up the illegal and accidental discharges of wastewater before tackling the finer points of more advanced clean up.
Jonathan Wong Woon-chung, another council member, said officials should clarify to what extent illegal discharges and improperly connected pipes contributed to water pollution. He also questioned whether the upgrade would have the intended effect, as improvements might be offset by cross-border pollution.
As a side note, the Kai Tak nullah, has been renamed Kai Tak river and has seen the return of grey mullets. This drainage channel in the old airport area is a catchment for several rivulets from the foothills of the Kowloon mountains, but was surrounded by rapidly growing factories and homes from the 1960’s to the late 1980’s which discharged all their effluent into it. It was so badly polluted and foul smelling that at one point there was a plan to completely cover it up and make it subterranean! Luckily science prevailed in the planning and there is now a scheme to remediate and green the area and especially the river. Obviously this wi take years, but the effort seems to already be beating fruits. See the project website here for more details.
Once a swampy backwater of fewer than 20 million people, the Pearl River Delta—the southern swath of mainland China above Hong Kong—now has three times that population. Tens of millions more humans in the Pearl River Delta means many more toilets a-flush, pumping a steady gush of human waste into the South China Sea.
Read the full story at Quartz