FINAL VERSION Murray River Carp Action Plan

 

Introducing Carp

The binomial name for carp is Cyprinus carpio. They belong to the Cypriniformes order and the Cyprinidae family. They are freshwater fish. They are an edible type of fish but are also bred as ornamental fish. They range from 30-60cm. They are native to Asia and Eastern Europe. Their backsides range from an olive green to silver colour. They have pale undersides. Ornamental carp (mainly koi) are bred to become colourful but lose their colour and shape after several generations in the wild. Most wild carp prefer plain colours. Carp can be found with a variety of different colours and textures. There are two pairs of barbels (whiskers) at each corner of their mouth.(Four hairs in total) This is only seen on the carp and can help distinguish different species from the Cyprinidae family. Their individual scales are round. They can grow to large sizes and live for a long time. Wild carp generally cannot grow or live as large or as long as a domesticated carp can.Wild carp are smaller and longer than domestic carp. (ブリタニカ国際大百科事典小項目電子辞書版By Britannica Japan Co., Ltd. ©2010コイcarp) Some goldfish types which have slim bodies and look like carp can live for twenty years. Carp would be able to easily live longer than that. Some live over 65 years. Those slim-bodied goldfish can jump out of goldfish bowls on their first day in a way similar to carp. Large-sized carp can leap out of the water or at least surprise anything in its vicinity with the sound of water exploding when they feel frightened or threatened. They can tolerate an extensive range of environments and adapt easily. However they prefer warm, still or slow-flowing waters at low altitudes in the mid to downstream. They overcome and tolerate poor water quality, low oxygen levels, moderate salinities, pollutants, toxicants and high turbidity without difficulty. (Industry & Investment NSW, NSW Control Plan for carp 2010.) Low oxygen levels can be tolerated by gulping for air at the surface of the water. They have extraordinary strength and can continue gulping for long periods of time. Goldfish get tired and sick after gulping while carp do not. Carp are omnivorous in the same way as goldfish are.Their diet varies depending on the environment. They suck mud and water from the bottom of the river and filter the unnecessary things out with their gills. Big food items can be chewed with their teeth in the throat. They can eat molluscs, crustaceans, insect larvae, seeds, plant material, general organic matter, fish eggs and larvae, worms, crawfish and various types of plankton and bog moss.(Wikipedia, Common carp 2015.)

How carp entered the Murray River

Carp were introduced into Australia as early as 1859 in Victoria. It was mostly unsuccessful. In 1865 near Sydney carp were introduced and were continuously introduced in various areas including the Prospect Reservoir. Carp probably entered the Murray-Darling Basin around the 1920s. Different strains were also introduced to different areas with little records. During the 1970s, there was widespread flooding that linked many areas that used to be isolated and the introduction of several new strains. This led to the previously uncommon carp to become widespread and populated throughout the Murray-Darling system. Carp entered the Murray River through deliberate introduction and stocking to imitate European environment and through accidental escape of koi and small carp being used as live bait. Some people release their koi to rivers for various reasons. Most carp have some sort of koi ancestry. Natural migration to find better breeding grounds can be stopped with carp separation devices (e.g.Williams Carp Separation Cage) designed to capture carp and automatically release native fish and carp-exclusion devices (fish screens). Some waterbirds can accidentally spread carp through the transportation of eggs.

Carp are currently distributed throughout parts of NSW, Victoria, the Australian Capital Territory, South Australia, Tasmania, Western Australia and Queensland. There are still some areas of the Murray-Darling Basin that do not have any carp in it. These areas are great places to research whether carp actually are responsible for many of the problems that are blamed on them. However, most of these areas are high-altitude areas or differ in some way with the areas already infested with carp. Some of them are inaccessible due to natural and artificial barriers such as waterfalls and large dams. It is highly important to maintain the carp-free status of these places through various methods. (Industry & Investment NSW, NSW Control Plan for carp 2010.) There are many different species of carp. The common carp (European carp) is the most well-known species. Interbreeding, cross-breeding and other types of breeding has increased the variety of carp throughout the world.

The impact of carp on the environment

There are still some doubts as to whether carp are directly involved in the decline of the ecosystem health of the Murray-Darling Basin. They are blamed for reduced water quality, algal blooms, erosion, reduction of macro-invertebrates, reduction of native soft-leaved, shallow-rooted and submerged aquatic plants, various diseases and reduction in native fish numbers. However, some of these problems are also caused by human activity. Simply making the rivers carp-free may not be the best solution to these problems. A combination of factors could be responsible for the observed degradation in river ecosystems.The main focus of people’s attention is the destructive feeding habits of the carp. They stir up sediments and uproot vegetation. The increased levels of silt in the water blocks out sunlight and causes native aquatic plant numbers to decline. Native fish that rely on sight to feed will suffer. Plants can also be smothered and gills of fishes clogged by the sediment. Cleared vegetation near rivers results in run-off containing sediment. This is also a primary factor in the reduction of water quality.Carp are regularly blamed for declining native fish numbers. Although they do affect native fish in many ways, there are way too many other factors which relate to human activity at play as well. Native fish populations were already declining before the 1970s because of human activity. The carp is only taking the place of the native fish. Carp has been a scapegoat for a long time. Getting rid of carp will only help a little. The state of the rivers will most likely remain the same for some time. (Industry & Investment NSW, NSW Control Plan for carp 2010.)

Research in North America has indicated that carp are pests and have to be eliminated. Australia is different from North America and more research is needed for the true impact of carp on the environment to be known.

Strategies being used, trialled or investigated in Australia to solve this problem

I have seen a documentary in Japan about the battle to get rid of carp in America. People from scientists to locals tried all kinds of strategies but were unsuccessful in reducing the carp population. It is a futile battle. Most of the time, it is useless. What is needed is research. Everything must be made clear before devising a strategy. Currently there are many strategies being used to control the carp population. Community carp fishing competitions are popular but useless. They can perhaps get rid of quite a lot of carp but have little impact on the long-term. Commercial fishing can get rid of large volumes of carp but carp populations quickly recover. A popular poison that kills fish is rotenone. It is obtained from the roots of several tropical and subtropical plants. It is illegal to use it on fish and only those with permits can use it. There are many terms and conditions which limits it to rare circumstances. Rotenone is not a possible solution to the carp problem. Fishway carp separation devices have the possibility of widespread use but are hindered by the lack of ways to dispose the captured carp. Newer carp-exclusion methods (e.g. screens and ‘finger’ style pushing trap) can be used successfully without blocking native fish. Draining and drying is a popular method which has many variations. Screens are needed for better outcomes. However consultation with local agencies is required. Manipulation of water flows to keep the water levels low and falling can stop the carp from spawning and strand them in drying wetland. My favourite method is the breeding and stocking of native fish. Daughterless carp technology requires many decades before the carp population becomes mostly males and dies out. Only carp will be affected and other native fish do not have any involvement. Public consultation is required and this technology may not be successful. Many years will be needed before the implementation of this strategy. The koi herpesvirus did not break out in Australia and can almost certainly wipe out the entire carp population. If resistance against this virus develops, the plan will fail. Interbreeding between goldfish and carp could reduce effectiveness as goldfish are resistant to the koi herpesvirus. However there is a virus that can kill goldfish without any signs or symptoms. More research will be needed on many viruses and fish before action can be taken. The rotting bodies of hundreds of carp will almost certainly affect water quality. The public may not accept this strategy.(Industry & Investment NSW, NSW Control Plan for carp 2010.) The main point is that more research must be done on these topics.

My Own Murray River Carp Action Plan

Since I have not been researching any topic related to carp elimination and I am not and will not become a marine biologist, it is unlikely that my own action plan for addressing this issue will be practical and justified. I believe that more research into carp and the Murray-Darling Basin is needed and until then, the current strategies can be implemented to at least somewhat control the population. My action plan would be to continue the current strategies and research as well as the breeding and stocking of native fish. I really like the idea of breeding and stocking native fish. It targets the main problem of carp, which is its very high reproductive rate. The focus should be shifted from carp to the human activities that are actually creating the problems. Education of the general public is also important. Purchasing products such as carp-based fertilisers or pet food may also support the commercial harvesting of carp. Most of the eggs and larvae of carp die before reaching adulthood. However the percentage that dies is considerably lower in areas where carp is considered as a pest. This percentage can be raised through restocking of native species. Depending on the temperature of the water, the eggs hatch within a week. Therefore it is hard for bacteria, fungi, and the vast array of tiny predators to reduce the number of eggs. Large predatory native fish, such as Murray cod, golden perch and bass are able to consume juvenile carp but don’t consume large amounts. They don’t seem to like eating carp. They may also eat eggs but there is limited time for them to consume it.Their tendency of not eating eggs and juveniles of carp can perhaps be solved by only feeding them carp eggs and carp juveniles from a young age. When someone eats something all the time when they were young, they would grow to like it. Although this may create unbalance in the ecosystem, it is a strategy worth considering. Through the restocking of these native fish, the fish numbers will increase and eat more eggs and juveniles of carp. The population of adult carp would be significantly reduced. Adult carp have no predators apart from humans. Floods are the ideal condition for juveniles to survive. Floods have not occurred recently and this has directly reduced the population of carp. The 1970s saw an increase in the carp population and this was due to large scale flooding. Increased predation will most likely help create more balance in the ecosystem. {Professor Nobuaki Okamoto of the Tokyo University of Marine Science and Technology(who is currently the president of the university)国立大学法人東京海洋大学長岡本信明nokamoto@kaiyodai.ac.jp2015.} Stocking activities are managed in accordance with the Freshwater Fish Stocking Fishery Management Strategy.(Industry & Investment NSW, NSW Control Plan for carp 2010.) More support, funding and education is needed for stocking of native fish to succeed in eliminating carp populations. Birds are known to eat fish eggs and juveniles. Bird researchers should investigate how birds can reduce the carp population.

Bibliography

 

Aquatic Biosecurity & Risk Management Unit, Industry & Investment NSW Orange, November 2010, NSW Control Plan for the noxious fish carp Cyprinus carpio http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0010/306010/nsw-control-plan-for-carp.pdf, (accessed 14 Aug. 2015).

“コイ(carp)” 2010, ブリタニカ国際大百科事典小項目電子辞書版, Britannica Japan Co., Ltd.

Discover Murray River 2015, Fishing in the Murray River offers a variety of fish species http://www.murrayriver.com.au/fishing/, (accessed 14 Aug. 2015).

“コイ【コイ（鯉）】” 2010, 百科事典マイぺディア電子辞書版, Hitachi Solutions, Ltd., Japan

“フナ【フナ（鮒）】” 2010, 百科事典マイぺディア電子辞書版, Hitachi Solutions, Ltd., Japan

National Geographic Japan 2008, ビジュアル科学大事典, “生態学” from Chapter 3生物学(Biology)

“こい【鯉】” 2010, デジタル大辞泉, Shogakukan, Japan

State of New South Wales through NSW Department of Industry, Carp control information http://www.dpi.nsw.gov.au/fisheries/pests-diseases/freshwater-pests/species/carp/control-information, (accessed 14 Aug. 2015).

“生態系とその保全” 2014, 【新課程】チャート式®シリーズ　新生物　生物基礎・生物, 数研出版株式会社, Chapter 10 p.420-449, Tokyo & Kyoto

Wikipedia 5 August 2015, at 14:10,Common carp https://en.wikipedia.org/wiki/Common carp, (accessed 14/08/2015).

Carp in Furukawa, Hiroshima Prefecture, Japan near a place where the landslides occurred. Photo: Noah Nishihara

Carp in Maribyrnong River, Australia  Photo: Wikipedia:Imagesof Wikimedia Foundation, Inc.

 

 

 

The reason we should protect the diversity of life forms existing today is because it has economic value. There are still many life forms that we have not yet discovered and begun to use. To maintain a variety of genes is to retain the possibility of the human race. The more life forms in an ecosystem, the more balanced and stable it is. Many life forms provide us with benefits. There are spiritual benefits from the diversity of life forms that makes our hearts and lives more fulfilling. The importance of nature in our survival is always remembered with the tragedy of Easter Island. We must save energy, recycle and not waste anything. There is much that can be done by one person. We must not exploit resources. Rivers, creeks and wetlands must be used wisely and sustained.