Protecting Fish Habitat
Community Based Sustainable Fishing Education Project Information Sheet #4
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Protecting Fish Habitat - FAQ, References and additional resources
Importance of Habitat types
The health of habitats is influential on the quality of the fish community however the need for a variety of habitats is often overlooked. A variety of habitats is required to fulfil the different needs of fish throughout their life cycle. The King George Whiting for example requires at least 5 different habitats to full fill its lifecycle (PIRSA, 2007). These habitats are: mangrove forests, salt marshes, shallow seagrass meadows, deep seagrass meadows and offshore reefs (PIRSA, 2007). The health and availability of each of these habitats is important to the sustainability of this and many other important fish stocks. It is therefore important that we as recreational fishers do our part to preserve all of our diverse and sensitive marine and freshwater habitats.
Laegdsgaard & Johnson (2001) found that the complex structure of mangroves provide maximum food availability and minimises the incidence of predation in small juvenile fishes. This provides evidence of the importance of mangrove forests to the health of species such as King George Whiting, Yellow Fin Whiting, Bream, Mullet and Mulloway (Laegdsgaard & Johnson, 2001). There is only one species of mangrove (Avicennia marina) found in South Australia of which approximately 25% have been lost along the metropolitan coastline since 1954 (Kinhill & Sterns, 1985 cited in Edyvane, 1998). Due to changes in sedimentation rates due to a loss of seagrasses mangroves have started to propagate seaward (Edyvane, 1998). However due to nutrient pollution large ulva mats are smothering new shoots and the pneumatophores of adult plants (Edyvane, 1998). Further restricting the area mangroves can cover. For the health and sustainability of the marine environment it’s important that mangroves be protected and repopulated to preserve and encourage an increase in fish communities.
Mangroves are also migrating inland, outcompeting biologically and ecologically important saltmarsh communities (Harty, 2002). Saltmarshes provide an important nursery and feeding habitat for many marine invertebrate, fish and bird species (Harty, 2002). Unfortunately the saltmarsh communities along the metropolitan coast where biodiversity and endemism are highest, development pressure is greatest (Edyvane, 1998). This has caused a loss of approximately 80% of saltmarsh communities and 100% loss of the saltwater tea tree, reed beds and native grasses (Edyvane, 1998). It is therefore important that the remaining saltmarsh communities be protected to preserve the biodiversity and ecology of our unique gulf waters.
Seagrasses are very sensitive to nutrient pollution and increased sediment load in the water column. Seddon et. al. (2005) reported that the increase in anthropogenic pollution and coastal development along the metropolitan over the last few decades coast resulted in the loss of approximately 5200 ha of seagrass habitat. Seagrass plays a pivotal role in the health of the marine environment by: stabilising sediment, being a primary producer, providing food and habitat for a variety of marine organisms (Seddon et. al. 2005). In an attempt to repopulate the metropolitan coast with Posidonia species SARDI scientist trialled a donor independent method of planting seedlings (Seddon et. al. 2005). As seagrasses are an integral part of the marine ecosystem it is important that recreational fishers do as much as possible to limit their impact on seagrasses. Things that you can do to limit your impact are: do not flush fertilizers, pesticides, herbicides down stormwater pipes; do not anchor in seagrass meadows, anchor in a sandy patch and let rope out to reach your spot and do not relocate pest species such as Caulerpa taxifolia.
The rocky reefs of central and northern metropolitan beaches have been long suffering from nutrient pollution and increased turbidity (Gaylard, 2003). Sewerage/stormwater outfalls and polluted water ways have been blamed for polluting the marine environment and damaging reefs and seagrass communities (Gaylard, 2003). Reef health is declining due to the domination of opportunistic species feeding off of the increased nutrients and by the smothering of plants and organisms (Gaylard, 2003). Rocky reefs are important for sustaining biodiversity and ecology, as they provide food and habitat for many endemic species (Gaylard, 2003). If reefs are to recover from the decades of damage the quality of water coming from sewerage/stormwater outfalls and polluted waterways needs to be improved (Gaylard, 2003). That is why programs such as cleaning up Christie’s creek are so important to the health and recovery of local reefs and seagrass communities.
Wetlands are an important natural filtration system that could be effective in reducing nutrient and sediment load in sewerage/stormwater outfalls and polluted waterways (DEH, 2007). Wetlands also support diverse assemblages of both marine and freshwater fish and crustaceans as well as mammals, reptiles, amphibians and birds (DEH, 2007). Unfortunately South Australia has already lost 70% of its native wetlands, this is why it is important to preserve and restore those still remaining (DEH, 2007). It is suggested that not only should these wetlands be restored and protected but that more wetlands should be constructed so they can be utilized to filter and clean our waste water, rivers, creeks and streams before they enter our gulfs.
Information on the health of the coastal marine environment along the metropolitan coast can be found at: http://www.springerlink.com/content/l515h23567q6k102/fulltext.pdf
Information on the state of mangroves and Saltmarshes can be found at: http://www.coastal.crc.org.au/coast2coast2002/proceedings/Theme6/Planning-mangroves-saltmarshes.pdf
Information on the health of metropolitan reefs can be found at:
DEH, 2007 Wetlands of South Australia can be found at: http://www.environment.sa.gov.au/biodiversity/wetlands.html
Edyvane K.S.1999, Coastal and marine wetlands in Gulf St. Vincent, South Australia: understanding their loss and degradation, Wetlands Ecology and Management 7: 83–104
Gaylard S, 2003, The health of subtidal reefs along the Adelaide metropolitan coastline 1996-99, EPA report.
Harty C, 2002, Planning for Mangroves and Saltmarshes, Coast to Coast, page 145-148
Seddon S, Wear RJ, Venema S, Miller DJ, 2005. Seagrass rehabilitation in Adelaide metropolitan coastal waters. ll. Development of donor bed independent methods using Posidonia seedlings. Prepared for the Coastal Protection Branch, DEH. SARDI Aquatic Sciences Publication No. RD004/0038-2. SARDI Aquatic Sciences, Adelaide.
PIRSA, 2007, http://www.pir.sa.gov.au/fisheries/recreational_fishing/target_species/king_george_whiting accessed on the 6th March 2008
DEH, 2007 Wetlands of South Australia: http://www.environment.sa.gov.au/biodiversity/wetlands.html accessed on the 6th of March 2008
www.stormwater.org.au - a great resource regarding stormwater issues and practical ways to help. Click 'give me more information' to access plenty of easy to read information and advice
The following is an article written by FFC Steering Commitee Member Cassie Price and was used as the basis for the Info sheet:
Protecting fish and fish habitat when you are on the water
What is good fish habitat?
Good fish habitat is somewhere where fish like to shelter, feed and breed. This could be for all ages of fish, but nursery habitats are even more important. There are some main areas of fish habitat that we spend a lot of time fishing in or near, including;
- Wetlands (fresh and brackish water)
These fish habitats all have some key elements that make them important;
- Water of good quality
- Plants for shade, to hide in and provide food
- Food source, in the sediment, in the water and growing on the plants
- Safe passage to the next habitat
Wetlands are areas that are important to keeping the water quality of our creeks good enough for the fish. They are often the freshwater swamp or swamp forest at the back of the creek, usually behind the mangroves or saltmarsh.
They act as filters, ensuring anything nasty in the water is caught before it enters the creek. They also provide a food source, some of the goodies that get washed from the wetland to the creek in high-rainfall can be an excellent food source for fish.
Wetlands can also be the breeding and nursery areas for fish that need to migrate upstream, often into freshwater to breed.
Saltmarsh are the areas in behind the mangroves that get less tidal water over them, sometimes they are only wet on king tides. They have small ground cover and bushy plants that are highly salt tolerant. Don’t be fooled!!! These are one of the most important fish habitat areas there are. Especially as a food source for fish and for safe nursery habitats for fish when they are covered with water.
Saltmarshes are also particularly important to crabs, they spend much of their time in saltmarsh areas.
Mangroves are the forested areas within the high tide zone. They are made up of a number of specially designed tree species, that we all know as mangroves. They have water over them much more than saltmarshes and therefore are day-to-day habitat for all sorts of fish.
They are particularly important in sheltering smaller and juvenile fish and providing a very important food source.
Seagrasses occur where they are always covered in water. They are a very important food source and breeding area for many fish. Seagrasses also form day-to-day habitat for many different types of fish.
Reef areas are places that we love to fish and we know that fish like to hang-out around them. They are attracted by the food and shelter. Many of the juvenile fish that sheltered in the saltmarsh, mangroves and seagrass while they were growing up, migrate to the reefs to live.
How can fish habitat get damaged?
All fishermen can recognise good fish habitat, as we all know how to think like a fish! But can we recognise when we might be doing something to damage their habitat?
The important elements of fish habitat; listed above, are finely balanced, any disturbance to these elements and the fish habitat area may quickly become unpopular with the fishy-locals.
Water of good quality
Healthy water is water without pollutants (oil, fuel, rubbish), without excessive algae growth and without too much suspended soils (turbidity or murkiness).
Anything that is directly spilled or washed into the water can unbalance the good water quality. Nutrients from farms, golf courses, sporting ovals and your lawn can lead to lots of algae growth that can choke waterways and fish.
Soils from exposed areas of land and from bare eroding streambanks will also end up in the water with the next drop of rain, it can severely damage fish habitat by smothering plants, filling in deep holes and breeding areas. It can also choke fish by clogging their gills with silt.
As fishermen we all target the areas that have some ‘structure’ to fish around. These snags are super important to fish, but they are often moved or removed for safe boat passage or to make the creek look ‘tidy’! With no snags, there is nowhere for the fish to breed, lay their eggs, hide from bigger fish or ambush the little fish.
It is also important to remember where snags come from – the trees on the streambank, without any trees on the edge of the water there would be no snags in the future.
Plants for shade, to hide in and provide food
All sorts of different plants are important to be in and around the water, they all have a purpose as fish habitat, to provide food or shelter and also to provide shade.
Water temperatures are very important to fish and without some nice shady trees near the water, the water can become very warm and not suitable for fish. The sunlight can also make them easier to see, so they can be easily spotted by predators, in and out of the water – fish prefer shady areas to hide in.
Different sorts of plants might include; floating plants, those growing under the water, those growing up out of the water and those on the bank. They all have an important purpose.
Food source, in the sediment, in the water and growing on the plants
Where there is good water quality and good vegetation lots of little waterbugs and other critters that are tasty to fish will live in the sediment and the water. These areas are prime for fish, as they are attracted there by the food. Keeping those two elements in good health will ensure a permanent ‘café’ for the fish to keep visiting!
Safe passage to the next habitat
It is not only important that the fish have places to hang-out like we have mentioned above, with plants, shade, food and good water – they also need to be able to get from one of these nice ‘cafés’ to the next safely. Continual passages of good fish habitat are incredibly important. The more fish habitat there is, the more fish can be housed there!
For example; you wont get any tourists to your motel if you are cramming 20 per room and feeding them rations! But they will breed up, tell their friends and come in their thousands if you are offering space, plenty of food and a good time!
Some fish even have to migrate to breed, if they are unable to move safely to their breeding grounds, then they simply wont breed and there will be no little fish that year (or any year in the future if the blokage remains).
It is important to remember that blockages to fish passage can be in a number of forms, the fish may not feel safe to move between habitats if they are not sheltered, the flow could be to fast for them to move upstream, their might be a plume of hot water or dirty water that they cannot move through or their might be a physical blockage such as a road culvert that they cannot pass.
What can you do on the water?
There are some key things that you can do while you are on the water to protect that great fish habitat that keeps you fishing that same spot year after year!
- Be aware of what you are putting into the water
- Don’t let any of your rubbish, even little bits of line and bait bags, end up in the water
- Don’t change oil or fill fuel tanks once you are on the water or even near the water (ie. the boat ramp), those nasties will run straight into the water
- Don’t use stainless steel hooks, they can remain in the water for many years after you have left
- Try not to move or disturb any snags in the water, if you do need to shift one for safe boat passage, make sure you don’t move it far and that it stays mostly in the water – never take them out of the water all together
- When fishing on reefs, be aware that your anchor will be doing a lot of damage to the favourite fish ‘café’. Drift if you can or place the anchor just off the reef – on sand and let the rope out to get you back over the reef to fish
What can you do on the shore?
- Be aware that what you put on your lawn, your farm, your driveway; will end up in the water and will add to the nutrients, soil and chemicals in the water
- Be careful of the plants you are driving on or standing on, if you do need to drive or walk over vegetated areas, go out the same way you got in for minimal damage (let others know to do the same thing)