Teach a man to fish a lot!

Hi there, welcome back.

Last week we had a run through the evolution of Hong Kong's fishery practises over the last 80 years. We observed that Hong Kong's fishing fleet evolved from low tech, mostly wind powered, vessels to a predominantly mechanised fleet. This mechanisation, and the newer fishing practises that it enabled, resulted in yearly increases in fishery yields. Although these increases are associated with an actual decrease in per unit yield (basically catches are becoming smaller so an increased number of catches is require to meet the demand).

This post is going to have a quick look at three dominant fishery methods utilised by the Hong Kong fleet:

Gei Wai (fish ponds):

Gei Wai are large bunded ponds that can be either replenished tidally or through deviation of freshwater sources dependent upon the culture (Lai et al, 1999). They are effectively nurseries where young fish, shrimp etc. are introduced and allowed to mature in a relatively protected, and easily farmed habitat (www.wwf.org, 2014).

As I'm sure you've already realised, this method requires a large areas of coastal land (perpetually at a premium in Hong Kong) and as such the practise is slowly being ousted in favour or less spatially demanding methods. Gei Wai now predominately survive in the very northern portion of the new Territories (Lai et al, 1999) on government owned land.

Marine Culture Cages:

Culture cages are large, fine grated cages suspend from rafts in coastal waters. The practise was adopted in the 1960s after growing population demands required a greater output from marine resources.

Gei Wai and Fish Culture Zones in 1998, courtesy of www.afcd.gov.hk.

Although the method thrived for approximately 20 years (Morton, 2005) this flourishing new industry couldn't sustain itself for very long. Typically the farms were situated in protected environments (shallow coastal bays etc.) in order to allow the livestock to growth as quickly and easily as possible.

However, the low current energy of these protective areas prevented the excess chum and supplements that were fed to the fish from being transported away from the farm area resulting in a rising levels of local nutrient pollution.


The increasing levels of marine population deriving from Hong Kong's rising population also had a severe impact on Cage fishery. Perhaps most notable impact event is the 1998 'Red tide': a significant algae bloom swept across Hong Kong and decimated caged cultures and corals. The bloom affected 25 of the culture zones in HK and resulted in a loss of approximately 2,500 tonnes of fish culture at an estimated HK$250,000,000 impact on the Hong Kong economy (Yang et al, 2003).

Capture fisheries:

A quick referal to the ever useful 'Hong Kong: The Facts' government released fact sheet (www.gov.hk, 2014) gives us a summation of Hong Kong's modern fisheries fleet:

• 33% of vessels are >15m and carry out activities outside HK local waters, along the northern continental shelf of south china sea: Trawling, Line fishing and Gill netting.
• The remaining two thirds of the fleet comprise smaller vessels whose activities are generally carried out inside HK local waters (Gill-Netting, Line fishing, Purse Seiners and Cage Trapping).

For the sake of brevity I am going to focus on, arguably, the most impactful of these capture methods: Trawling. I feel that the other techniques, whilst clearly impacting the environment, can pretty much be regarded as a single entity that represents the exploitation of shallow marine ecology. Although many of the techniques are similar to trawling, they typically do not disturb the seabed envrionment to the same degree.

The trawling method involves dragging large nets across, or near, the seabed in order to catch fish and Crustacea.

Basic trawling method, courtesy of web.duke.edu.

The environmental impacts of trawling have long been recognised (Van Dolah et al, 1987) and consist of two primary effects:

• Huge plumes of sediment are disturbed by the nets. Similar to the side effects of reclamation the spread of the disturbed sediment can spread across huge areas preventing phytoplankton photosynthesis (Yan et al, 2013). Fish species also have 'varying tolerances of suspended solids' (Newell et al, 1998. Page 25) and may suffer clogging of the gills eventually preventing feeding and causing death.
• The second impact is a much more obvious and severe matter; the act of dragging a net (complete with ballast to maintain negative buoyancy) literally scours a path across the sea floor destroying habitats in its way. Coral reefs are particularly susceptible to this destruction due to the slow growth rate. Years of growth can be removed in a single pass (Hall-Spencer et al, 2002).

The severity of trawling impact on marine ecology is such that in early 2013 the practice was banned inside HK local waters, given Hong Kong's establishment and ubiquitous association with fishery practises the acknowledgement of trawling's destructive capability was a huge step. An article, released on the day of the bans commencement by the South China Morning Post (www.scmp.com, 2013) stated that HK$1.7 billion were due to be paid out as compensation to affected companies and fishery families.

Above is a quick Youtube clip issued by www.seafish.org. It's not an immensely exciting clip but I think it really allows you to comprehend just how much damage trawling could do across delicate marine ecologies. Scary!

Teach a man to fish

Unsurprisingly, a major reason for Hong Kong's original settlement and early expansion is due to it's exceptional marine resources. The East China Sea, South China Sea and freshwater outflow from the Pearl River provide large expanses of varied aquaculture.

The increasing population of Hong Kong and its demand for these fishery resources has resulted in their severe over-exploitation with little to no evidence of improvement. A study, commissioned by the Agriculture, Fisheries and Conservation Department of the HK government, identified that over the last 25 years catches have decreased by almost 50%. In addition 12 of 17 commercial species in HK waters have been identified as being "heavily over-exploited" whilst the remaining 5 species are "fully exploited". The study is referred to in  the Fisheries Protection (Specification of Apparatus) (Amendment) Notice (2011) by LegCo (Hong Kongs Legislative Council), although the original document seems to be elusive, if you come across it please let me know.

Perhaps its the years I spent in my previous discipline of archaeology speaking but I feel that to appreciate the current state of affairs we really need to step back a little and take a quick look at how HK reached this situation. An article by Morton (2005) describes HK fisheries evolution from larger, slow growing species that are worth more to smaller, faster growing species that are worth less. The article, whilst not referenced, touches upon some of the land marks in this evolution, with a little fleshing out we can develop clearer idea of how the HK's fleet has evolved:

• The 'Fisheries Research Unit' (FRU) was conceptualised in the late 1930's (Morton 2005), although the its official establishment appears to have occured some 20 years later (Mellor 1981, pg 198). The FRU's aim was to determine how HK's technologically inferior fishing fleet could compete with Japans relatively mechanised, larger fleet which shared portions of the same waters and targeted the same species, effectively directly competing with China and HK for marine resources.

Late 19th Century Chinese fishing 'Junk', Courtesy of hongwrong.com

• The 2nd Sino-Japanese war saw the occupation of China. During this time the Japanese possessed a monopoly on fishery resource exploitation in the East China Sea. As a result supplies of fresh fish to HK were reduced to near zero (and as we have already seen Hong Kong is heavily dependent on imports from China). HK fishery was forced to deal with an overnight increase in demand, fairly at odds with its current, at the time, methods.
• However, Japanese occupation of HK towards the end of the war sparked a technological renovation of the local fishing fleet allowing  larger catches from larger areas to be acquired (Morton 2005).
• In 1960 a refreshed governmental focus on the state of HK's fleet began. The government assumed control of, and invested in,  the FRU (Chan et al, pg 4: 1996). Representing an official governmental recognition of the potentially troubling situation. This governmental interest and investment continued steadily for around twenty years.
• After governmental intervention the catch totals of the HK fleet were noted to rise annually from 53,000 to 224,000 in 1990. However, whilst fishery totals increased year on year it is reported that the catch per capita began to steadily decline from the late 1980's onwards. These declines are noted not only in Hong Kong but worldwide. Anderson et al's (2011) studies of trends in the expansion of invertebrate fisheries reflects Mortons conclusions of a declining trend in marine catches, albeit on a global scale, noting that total catches of marine invertebrates rose from 2 million in 1950 to 12 million present day (2011). Whilst the factors governing each decline are not identical (as we may venture into next time) they both involve a core theme of increased activity and exploitation reaching a tipping point, beyond which the environment cannot cope with the strain.

Join me next time when we will take a look at the methods that Hong Kong utilised during the enhancement of its fisheries.

After reading Anderson et al's (2011) on invertebrate fishery trends I started to read up on Sea Cucumbers.... I urge you to do the same: LOOK HOW CRAZY THEY ARE!

Courtesy of NationalGeographic.com