Part 2: Overfishing? Not quite

Its effect depends on the sort of pollution - in some cases poisonous contents of effluence may kill the fish, in others continual pollution may have a long-range effect on some fish or even on the whole ecosystem, by causing disease or weakening the fish, thus increasing their susceptibility to parasites. At any rate, pollution, alone or in combination with other factors, often causes instant or prolonged impoverishments of fishery resources.

However, the share of pollution in any impoverishment of fish resources is very often studiously disregarded, played down or even suppressed. One way of doing it is to wrap it in a campaign against overfishing, thus favouring polluters on the expense of fishermen. Official fisheries science is feeding on data from the fishing industry and on data collected while test-fishing fish populations. It's doing very little, if at all, to study the effects of pollution on target stocks, their prey and food, and is not paid and empowered to search and analyse polluted waters and track the pollution all the way to its source. Consequently, its doomsday salvoes are aimed exclusively against the fishing industry.

Only recently, in a letter published in Science online, three scientists from Simon Fraser University criticised the Canadian government for cutbacks at eco-toxicology labs, which would further reduce any studies towards the effects of aquatic pollution on fishery resources.

The perils of pollution
Offshore and coastal pollution affects fish populations in many ways. Here are some:

Nutrient-rich sewage may cause rapid swelling of algal populations into blooms, such as the lethal to fish red tides. Algal blooms, wherever not grazed intensively by higher organisms, die off and rot, creating anoxic (oxygen depleted) ‘dead zones’, where fish if caught in die. Such events more often than not occur in inshore waters, where many fishes spawn, and their early stages feed and grow.

Upstream effluents of human and farmed animal origin may carry both fish and human diseases into coastal waters.

Industrial sewage, pesticides and chemicals used in urban and farming environments may carry toxins and carcinogenic (causing cancer) substances and heavy metals, such as lead and mercury, that are absorbed by low-level organisms. Those, consumed by plankton, which is fed on in turn by young stages and small fish and, up the food chain, are accumulated by the larger, food fishes (bio-accumulation). A wide range of metals and metalloids, including aluminium, chromium, copper and zinc, as well as organic pollutants may affect immune systems in marine organisms, making them susceptible to pathogens and diseases.

Oil spills as well as oil from land can be lethal to fish in several ways. Fish living or growing in oil polluted environment are often externally deformed and their internal organs lethally affected.

A team of American scientistswrote in the Journal of Aquatic Animal Health 10:182–190, (1998) that their research had shown that while various pathogens are present in all aquatic ecosystems, in adverse environments, such as polluted estuaries, pollution can substantially contribute to the spread of fish diseases, significantly reducing the size of the affected populations.

Coastal waters can also be affected by warm effluents from the cooling systems of electric and other coastal plants, which may affect such settled organisms, as corals and sea-grasses, thus reducing habitats essential for some fishes to live and others to breed.

Non-degradable plastic trash is dangerous to fish through direct contact, especially when fish (and also turtles) are taking plastic items for food.

Pollution devastates inshore habitats, such as seagrass beds, which form highly productive and diverse coastal ecosystems - nurseries for many fish species, and essential habitats for turtles, some aquatic mammals, birds, and other marine organisms. These are habitats where many fishes spawn and spend at least the early stages of their lives, where pollution can cause massive mortality of eggs and larvae and bring about substantial damage to whole year classes. Nonetheless, scientific research into this subject seems to suffer from chronic starvation. For example, J C Jones and J D Reynolds reviewed in Reviews in Fish Biology and Fisheries7(4) the effects of pollution on reproductive behaviour of fishes. The authors who had searched 19,199 studies in Aquatic Sciences and Fisheries Abstracts and other sources published during 20 years found that only 0.1% (19) of them linked pollution research to reproductive behaviour of fishes. Eleven of the 19 studies found abnormal reproductive behaviour.

Pollution doesn't have to kill fish or make them sick. Sub-lethal concentration of pollutants may change the age and species composition of a population and interfere with their normal migration pattern, thus keeping them off their normal fishing grounds. Also, offensive pollution repels anadromous fishes from their home estuaries, streams and rivers.

Many pollutants produce genetic effects upsetting the well-being and survival of species and in particular their young stages. Radioactive contamination can cause mutations through radiation on the genetic material. Oil and other organic pollutants may comprise also mutagenic compounds.

Down below
Those issues have been hotly disputed in Australia in the wake of major works to stretch a 450km pipeline from gas fields to a liquid gas terminal on Curtis Island off Gladstone harbour that involves dredging up estuary sediment. Almost a year ago, fishermen started observing massive mortalities of fish and other animals and deterioration of sea grasses in the Gladstone area, where waters became increasingly turbid. Over 40 fishermen got skin lesions in an epidemiologic outbreak of unusual diseases. They got sick at the same time as the fish.

Nonetheless, the official version of the government departments in charge and the Gladstone Ports Corporation was that the epidemic fish diseases and mortality in the area was caused by the 2010-11 floods. The government also has refused to release toxicology reports on turtles, which show elevated arsenic in their blood and to release the reports on toxic algae. According to an official press release, “...the current available information is too patchy to derive generalisable conclusions about the link between chemicals and immunosuppression for the marine species evaluated” - a classic example of officious hogwash. No wonder that Professor Barry Hart's review of the report says that it lacks credibility.

Amusingly, the precautionary principle that's routinely applied by fisheries authorities to fishing, and propagated by NGOs such as the World Wildlife Fund (WWF), Oceana and others, disappears in Gladstone's murky waters when it comes to pollution. Reportedly, the WWF's reaction to the fishery disaster and the ongoing deaths of turtles, dugongs and dolphins, and disease in sharks, was to keep blaming commercial fishing as the greatest threat to the Great Barrier Reef, notwithstanding the spring of 2011 plumes of sediment spreading 35km seawards off the Gladstone main dredging site.

At least, the World Heritage Centre and the International Union for the Conservation of Nature (IUCN) warned Australia that its Great Barrier Reef would be placed on the List of World Heritage in danger, unless it was protected from a slew of new port and infrastructure projects. Fortunately, the Gladstone Fishing Research Fund issued a report by Dr Matt Landos (www.gladstonefishingresearchfund.org.au), which demolishes the official hush-up attempts. In his interim reports Dr Landos documents ongoing disease processes occurring in fish, crustacean and shellfish populations in the Gladstone region and convincingly argues that the pathological changes observed both in the riverine barramundi and the oceanic fauna couldn't be the result of just floods in the area.

And this is only one, in this case Australian, example of the influence the all-potent petro-chemical interests exert over NGOs and governmental machinery, including fisheries science and management.

In the Mediterranean
Last autumn, following public protests, Egyptian authorities shut down MOPCO Petrochemicals Company in Damietta Port. A report authored by Dr Ahmed al-Ghobashy on behalf of the Scientific Committee investigating petrochemical industry in Damietta alleges that pollution endangers fishery there.

"Damietta is characterised by its rich aquatic environment, different from other parts of the country, which helped in the creation of the largest fishing industry in Egypt, employing more than 50,000 citizens,” reported Dr al-Ghobashy. "The year 2011 witnessed a decline in fish production following the establishment of an expanding number of petrochemical plants, which emit large amounts of smoke and, together with the port, release waste and effluents into Mediterranean waters and the navigation channel…"

He estimated the pollution inflow at over 3,000m³/hour, or 1.728 million m³/day, which changes the chemical and physical properties of the water and sediments in the port area, leading among others to a gradual rise in the percentage of ammonia and drop in the number of fish larvae.

"If the government does not stop the petrochemical plants and the Damietta Port from releasing their wastes into the sea…” the report said, “these contaminants will completely destroy fishing activity in the region.”