Editor's note: Kurt Derbyshire, author of the following essay, is senior policy officer for marine fish habitat with the Queensland Department of Primary Industries and Fisheries, Australia.
By Kurt Derbyshire
The Department of Primary Industries and Fisheries (DPI&F) in Queensland, Australia, is in the process of developing guidelines for "fish-friendly" structures. The guidelines will apply to aquatic infrastructure commonly developed along urbanized coastlines and waterways: piers, seawalls, marinas, boat ramps, boardwalks, and the like. Fish-friendly structures will:
- Cause minimal disturbance to natural fish habitats, and
- Provide an enhanced artificial habitat for fish, through innovative design features.
Here, the term "fish" is used in its broadest sense, and includes finfish, crustaceans, molluscs, etc.
The guidelines will apply to all Queensland waters, and will not be specific to MPAs. However, they will be particularly relevant to our set of MPAs called Fish Habitat Areas, discussed later. They may also be of interest to MPA managers elsewhere, particularly in regions with similarly growing coastal populations.
Aquatic infrastructure is widespread and is likely to expand with increasing coastal population pressure. Most of the Queensland population lives near the coast, and this is where most development occurs. Over the next 20 years, the southeast corner of the state (including the Sunshine Coast, Brisbane and the Gold Coast) is expected to absorb more than one-quarter of Australia's population growth. We believe that to achieve sustainable development, it is important that coastal infrastructure be designed for minimal impact on fish and their habitats, and that opportunities for beneficial use of artificial structures be capitalized upon.
The guidelines will emphasize the importance of minimizing damage to the natural habitats on which fish rely. Locating structures to avoid disturbance of critical fish habitats is a good place to start. Scheduling construction to avoid critical biological events (e.g., fish migration for spawning or recruitment) is also important. Once it has been determined that a particular location and time are appropriate for development, the challenge becomes how to enhance artificial structures as fish habitats, while still fulfilling their primary infrastructure purpose. Increased physical complexity may provide the key to enhanced artificial habitat for colonizing organisms and fish that feed and shelter there. Possible enhancements on structures include:
- Irregular surfaces that provide more interstitial spaces and increased surface area to allow colonization by marine flora and fauna;
- Grate decking to provide "skylights" that allow light penetration to the substrate;
- Crevices in seawalls to house cryptic species;
- Floating rather than fixed breakwaters to maintain water circulation regimes;
- Adding habitat modules to structures to provide additional habitat. Examples of commercially-available enhancement modules include the Reef Ball (http://www.reefball.org) and the Fish Hab (http://www.berkley-fishing.com/new/story.cfm?WhatsNewId=1&Position=1).
One difficult subject that the guidelines need to address is the potential for aquatic infrastructure to facilitate "biological pollution". It is possible that artificial structures can provide stepping-stones for pest species to invade environments that would otherwise not support them. The guidelines will suggest measures for minimizing this risk.
Research into fish-friendly structures, and monitoring of the impacts of aquatic infrastructure, will be encouraged. Monitoring of habitat-enhanced structures may provide useful information to help guide future fish habitat management decisions. The guidelines will link to DPI&F's Urban Fish Habitat Management Research Program (http://www.dpi.qld.gov.au/fishweb/13347.html), which identifies potential research projects, including the use of artificial structures as fish habitats.
As mentioned above, the guidelines will apply to all waters in Queensland - including Fish Habitat Areas (FHAs), a type of MPA declared under the Fisheries Act 1994. FHAs are an important component of the state's strategy for sustaining fish stocks and their dependent fisheries (MPA News 6:3, "Urban MPAs: Protecting Marine Habitats in the Midst of Human Populations"). Development in FHAs is severely restricted, being largely limited to maintenance of existing structures and to development of community facilities such as public boat ramps and jetties. A network of 71 FHAs protects some 8000 km2 of critical coastal and estuarine fish habitats in Queensland, while allowing day-to-day community uses such as lawful fishing and boating activities.
The fish-friendly guidelines will emphasize that the potential benefits of artificial structures should not be used as justification for disturbing natural habitats; rather, infrastructure approval should be justified on the basis of need and benefit to the community. We hope that the guidelines will help to provide a balance between urban development and maintenance, or enhancement, of the productive capacity of fish habitats for Queensland's fisheries resources. We invite readers to contact us with comments or suggestions that could assist us in developing the guidelines.
For more information
Kurt Derbyshire, Queensland Department of Primary Industries and Fisheries, 80 Anne Street, GPO Box 46, Brisbane 4001, Queensland, Australia. Tel: +61 7 3225 1469; E-mail: Kurt.Derbyshire [at] dpi.qld.gov.au