By Brendan Trembath

Updated Wed Apr 20, 2011 5:51pm AEST

Use old oil rigs as fish nurseries, scientists say Researchers believe fish could find refuge within the rigs and be safe from the trawlers.

AUDIO: Oil rigs could have new ocean friendly role (The World Today)
Australian marine scientists are proposing leaving thousands of decommissioned oil rigs in their deep-sea spots indefinitely to become long-term fish nurseries.

The huge chunks are of steel are meant to be removed when they reach the end of their productive life, but the scientists say their approach could save the oil industry millions of dollars and protect vulnerable fish nurseries.

The Deepwater Horizon disaster a year ago showed deep sea oil exploration at its most destructive.

Eleven workers were killed and almost 5 million barrels of oil leaked into the Gulf of Mexico.

Now marine researchers at University of Technology Sydney are pondering the future of the more than 6,000 rigs still in the sea.

“There’s a huge number that are due for decommissioning – they’ve reached the end of their production life, there’s no more oil left and the question is what do we do with these structures?” Dr Peter Macreadie said.

“There’s actually not much habitat in the deep sea – not a lot of hard structured habitat, not a lot of reef and so by adding more reef the idea is that maybe you can boost production, you can boost the amount of fish.”

But it would take some major legislative changes to put the proposal into practice.

“Current legislation requires rigs to be dismantled and removed and recycled onshore if they can be recycled,” Dr Macreadie said.

“But we’re actually starting to think maybe there’s a much better use for those rigs and in some cases there actually isn’t the technology to remove these rigs.

“They’ve been in operation for 20-odd years and now we’re wondering actually, in removing them are we actually causing more problems than if we left them in place or if we moved them into the deep sea to form artificial reefs?”

Protection for species

Dr Macreadie says illegal fishing trawlers going through deep-sea areas are decimating coral reef communities and fish species.

“What’s really devastating about that is that these organisms that live in the deep sea, they’re slow growing, they reproduce very late in life and they are very vulnerable to exploitation,” he said.

“To give you an example, the orange roughy takes about 30 years until it can reach sexual maturity and breed.

“They form huge aggregations around structures in the deep sea and structures are very rare.

“When they form those aggregations fishermen have become aware of this and they can remove entire populations, generations and generations with one swoop of their net.

“So the idea is with rigs – which have a lot of hollow internal space – the fish could find refuge within those rigs and be safe from the trawl fisheries.”

Dr Macreadie says researchers do not know how long the defunct oil rigs will take to disintegrate.

“But we can say that many of these rigs have been in production for 30-odd years and they’re showing very little signs of decay, but at some point they will eventually disintegrate in the deep sea,” he said.

Dr Macreadie and his UTS colleagues have written an article published in the US journal Frontiers in Ecology and the Environment.

They hope to stimulate a rational debate about the future of the world’s rigs.

Dr Macreadie says he does not work for, consult, or own shares in any company or organisation that would benefit from the proposal.

Structure Fishing 101

written by Tim Allard

Structures are a big factor in fish habitat and certain types will concentrate fish.

Structures are areas where there is a variance in the depth or contours of the lake bottom.

If you’re new to fishing, knowing how to find structure and understanding how fish relate to it will dramatically improve your ability to find and catch fish. As a term, structure gets used a lot in fishing articles, television shows and presentations by professional anglers. In this guide I’ll define structure, discuss various types and share some tips for fishing them.

What is structure?

Structures are the physical features of a lake or a river bottom. From a fishing perspective, structures are areas where there is a variance in the depth or the contours of the bottom, and these changes can range from subtle to dramatic. Structures can be natural as well as human-made features of the underwater landscape. Structures are a big factor in fish habitat and certain types will concentrate fish.

Before I get any further, let me explain what structure is not. Sometimes cover is incorrectly used interchangeably with structure. Cover refers to objects in or on the water that provide shelter for fish, such as vegetation or a dock. Of course, finding structure and cover together can make great fishing spots (e.g., a hump with a dense weed bed), so it’s no surprise that the two terms get used interchangeably.

Some Basic Structures

Here are some common fishing-structures. A ledge is the beginning of a distinct change in depth. It marks the top of a drop, which is simply the sloping of the bottom towards deeper water. Ledges and drops are main structures that hold many freshwater species, such as walleye and muskie. Add a weedline in close proximity to a ledge or a drop and they can be prime spots.

A hump is a shallow area surrounded by deeper water and often a preferred piece of structure for bass. Humps are sometimes called underwater islands. A hole is the inverse of a hump – a deep pocket in the bottom surrounded by shallow water. Holes are favorite hiding spots of bottom-dwelling hunters, like catfish.

More Advanced Structures

The above items are some basic structures, but they also form the building blocks for more elaborate pieces of structures. What follows are some of the more common fishing structures, but this listing is by no means exhaustive.

One example is a spine. To imagine a spine, first picture an underwater hump as an elastic band. Take that band, stretch it slightly and you’ve got a spine. One of the most common places to find spines is as a continuation or off of a point from a shoreline, but others exist off the end of humps as well.

The contour of spines will vary, some even have fingers running off the sides of them, and their gradient, or slope, will also vary from steep to subtle. Like a hump, spines are surrounded by deeper water, with drops and edges on each of their sides. Long spines can be travel routes for fish as they move towards shore, transitioning from deep to shallow water.

The inverse of a spine is a cut, or trough, which can be described as elongated holes. Most common in flooded areas or reservoirs, many of these structures were streambeds in their former lives before water levels rose above their banks, submerging them. Of course, drops can sometimes contain cuts in their sides that are simply grooves that were not previously riverbeds. Again, these irregularities can attract fish and are worthy of fishing and their ledges can be particularly effective at holding fish or acting as route ways.

Still got that elastic? Holding both ends, bring them together slightly until the band bows. You’ve just created a saddle between two islands or underwater humps (your finger tips). Saddles can be great structures to fish with both deep and shallow water structures as well as being corridors for fish to follow as they move from one structure to the next. Depending on their disposition, fish may be anywhere on the saddle complex. They may be tight to the islands and feeding or positioned slightly off the saddle and inactive. In this case, it pays to know the behaviors of your target species and fish these areas accordingly, but when in doubt, pick the structure apart with different lures to work a variety of depths.

Another piece of structure is the breakline (sometimes shortened to break). A breakline is really just the edge of a drop that runs perpendicular to the shoreline. If you’ve ever trolled along the shore in an S-pattern, running between shallow and deep water, you’ve been fishing the breakline. Sometimes anglers will describe the different breaks as primary and secondary. The primary breakline is the first sharp drop in depth traveling from shore outward; the secondary following thereafter and another major drop in depth. Whether you think of breaks as walls or underwater stairs, they can be good structures to fish. Yet the entire breakline does not always hold fish. What makes them great fish-holding structures is when other elements (like a cut or a bend) or cover (such as a weed edge) are added to a stretch of the break.

Why is Structure Important?

Structure often concentrates fish. Structures provide different advantages to various species (such as corralling baitfish, providing an ambush area, or being close to deep water for comfort). For reasons like the three listed above, many species seldom stray far from structure. Learning how the fish you’re targeting relates to structure and being able to find structure on the water will increase your ability to catch fish. Structures can move you away from shorelines to intimidating expanses of water that may seem void on the surface, but what lies underneath can be fishing hotspots.

Putting Structure in Context

It’s important to keep in mind that structure is but one factor in the finding-fish equation. Finding structure can put you on fish, but it’s not an absolute that you’ll catch them. Structures are often feeding areas, but if there’s no food they’ll likely not hold fish. Weather conditions and seasonal patterns are also important to keep in mind and, again, are part of a larger equation to finding fish.

Other factors affecting if structures hold fish are temperature, oxygen supply, or water quality/light penetration. Since different species have different dispositions, some structures may appeal to certain fish and not others. For example, a 12-foot hump on a gin-clear, rock bottom lake may be a smallmouth bass hotspot, but too bright an area for walleye during the day. Yet at dusk and dawn it might concentrate light-sensitive walleye that move in to feed and ambush prey. Sometimes how well structures produce fish is all about timing and putting environmental and forage factors in your favor.

Using hydrographic maps and fish finders together can make finding structure a relative easy task.

How Fish Relate To Structure

As mentioned, food and environmental factors impact the mood of fish and thus, impact how they relate to structure. A common misnomer is that if fish are not directly on top of structure, they are not there or are not relating to it. Speaking in general terms, fish “on” structure are usually aggressive (add cover to the mix and things could change), while fish suspended “off” of structure are less aggressive or in a neutral mood, resting between feeding binges (unless baitfish are also suspended off the structure). Fish distanced from structure are still relating to it and catchable, so novice anglers should learn to fish both the actual structure as well as its surroundings. It pays to ask, “How do the fish travel to this spot? Is there an obvious route on my hydrographic map?” and “If fish are not directly on the structure, where might they be off of it?”

The Tools of the Trade & Finding Structure

As mentioned earlier, the easiest structures to find are those that extend from land, such as a point. The reason is obvious; one sees the gradual slope on land and knows this piece of structure likely continues into the water. What’s difficult is finding structure when there are not hints from land. This is where a fishing finder and hydrographic maps are critical.

Hydrographic maps illustrate the bottom contours and depths, showing where the structures are on a body of water. Of course the scale of the map will impact the detail of the features it shows. Depth finders are your underwater eyes. They provide a continual reading of the depth below your boat, and help you pinpoint depth changes and find structure. Using hydrographic maps and fish finders together can make finding structure a relative easy task, even on a new lake.

A recent addition to an angler’s arsenal are GPS units, which can hold hydrographic maps as well as store waypoints, allowing you to mark structure once you find it. Of course, carrying some buoys is also handy to help you stay on structure as you fish the entire area.

Tips for Fishing Structure

I won’t try and cover how-to fish the various types of structure in one article, but I will suggest a few tips. First off, working jigs along the bottom and around the edges of structure can catch several species of fish, anglers should not just concentrate on the bottom (whether using jigs or not). Consider trying lures to work other depths around the structures. Also, try and fish “off” of structure as mentioned earlier. By this I mean if trolling the breakline, weave out into deeper water to look for suspended fish. The same concept applies when casting areas, like humps, islands and saddles.

Here’s a tip: fish sometimes suspend off of structure around the same depth as the structure itself. So, a hump that’s 12-feet deep might have a pike several feet away from the edge of the structure, suspended at 12-feet over water with a depth of 25-feet. Another important tip, which I’ve touched on already, is learning to isolate prime structure by considering other factors influencing fish behavior (such as food, cover, environmental elements, and so on).

Once you’ve done your homework and found structure you think will hold fish – take the time and fish it thoroughly. Many anglers work large structures too quickly, and if a big trophy is relating to a certain, special area on the structure (often called “the spot on the spot”) you might pass over her.

Learning about structure is just another way of thinking to solve the “Where are the fish today?” puzzle. Use maps and read up on your favorite species and how they relate to structure and you’ll find yourself catching more fish. Large pieces of structure can be intimidating to fish, so take the time to look for the best areas (considering other fish-factors) and fish them thoroughly.
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Warmwater Lake and Pond Habitat Initiative

The Department’s fisheries biologists recently discussed the feasibility of installing fish habitat structures to mitigate for the absence or loss of physical fish habitat in some New Hampshire water bodies. This discussion was initiated because of the potential opportunity that exists to enhance warmwater fisheries through fish habitat improvement projects.

The overall goal of these habitat projects is to improve warmwater fish populations and the opportunities to fish for these species. An additional objective of installing shoreline habitat structures would be to increase youth fishing opportunities.

Improving fish habitat by installing structures has been a successful management strategy in use for many years in states across the U.S., as these structures can benefit both forage and sport fish populations in a number of ways. Habitat structures have been shown to provide important nursery areas for many fish species and can act to increase fish growth and survival. The abundance of forage fish species is often enhanced in areas with habitat structures, which in turn can increase the abundance and growth of sportsfish (this is especially relevant in some NH lakes and ponds where a decline or lack of forage fish and/or crayfish may be the result of the absence or loss of appropriate habitat). Additionally, studies have shown that habitat structures can increase nest density, spawning success and juvenile survival of both largemouth and smallmouth bass.

Using fish habitat structures in New Hampshire waters is currently in a conceptual phase and there is no firm timeline for when, where, and what types of structures will be used. Before formulating a specific plan, the Department’s fisheries biologist will first thoroughly review the existing scientific literature, inventory current habitat quality and quantity on various lakes and ponds, and communicate with anglers in an effort to better understand their interest in this type of initiative.

The Department is also actively pursuing a feasibility analysis of using fish habitat structures. The feasibility analysis will answer the following questions: Will fish habitat structures provide habitat for the fish species of interest? What types of structures have been used elsewhere and for what purpose? What types of structures (artificial or natural) are allowed under current regulations? What are the potential problems (maintenance, ability to obtain permits from NH DES, potential navigation issues, potential effect on other fish species such as invasive species) in using fish habitat structures? What are the costs of building, deploying and maintaining such structures? How will anglers use the fish habitat structures (i.e., how will they access them)? What monitoring efforts would be best suited for evaluation purposes?

Warmwater fish habitat projects offer an exciting opportunity to improve fish habitat and warmwater fisheries in New Hampshire lakes and ponds. Additionally, involving anglers in this process presents an excellent opportunity for the Department and anglers to work together towards the common goal of improving and sustaining our state’s fisheries resources for current and future generations.

CONTACT:
John Magee, Fish Habitat Biologist
Gabe Gries, Region 4 Fisheries Biologist and Warmwater Project Leader

How to Build Fish Cribs for Habitat
The approximate cost of a crib is about $10.00 each, and now there is a new way to help purchase cribs for Lake Chippewa Flowage. In the summer of 2002 friends of the flowage will have the opportunity to purchase $10.00 raffle tickets. A drawing will be held in October and the lucky winners will be able to schedule a free day with a local fishing guide for 2003.
The Chippewa Flowage was created over 75 years ago. In those 75 years many trees and stumps that harbored food and shelter for fish have disappeared through natural decay. Realizing the structure must be replaced for a healthy fishery, the Lake Chippewa Resort Association, along with the Chippewa Flowage Area Property Owners Association started building and placing fish cribs in Flowage waters. Since March 1996 over 2500 cribs have been built and placed by volunteers from these associations. Building Cribs:

The first step is to accumulate wooden pallets. Pallets are donated by various companies in Wisconsin and trucked to the flowage at our expense. Cinderblock, clips and strapping must be purchased to build cribs. Cribs are constructed by layering pallets separated by cinderblocks on each comer until it is 3 or 4 pallets deep. Then the “sandwich” is strapped together. At this point the cribs are loaded by tractor-forklifts onto special pontoon boats that have been totally stripped down to just bare decks. Workers then turn the pallet/cribs on edge to stuff in brush. It takes a lot of brush to fill each crib. Accumulating brush and stuffing the cribs is actually one of the hardest parts of the job. Finally , when the pontoon is totally loaded, the captain and workers shove off and the cribs are dropped off into new crib locations.

Meanwhile other volunteers are cooking and serving food and beverages to the hungry workers. A master map is kept by the associations, but not published. After all, the cribs are for the fish, not the fishermen!

Crib building is an on-going project. Members of both associations are committed to preserving and enhancing this great fishery for current and future generations. If you are interested in supporting this effort, look for Crib Program Raffle Tickets on your next visit or mail donations to: CFAPOE Adopt-a-Crib P.O. Box 555 Hayward, WI 54843-0555

Read more at the Washington Examiner: http://washingtonexaminer.com/news/2011/04/calif-agencies-sue-over-sucker-fish-habitat#ixzz1KBj6L3I7

The following story was posted in a Northern Wisconsin newspaper. Although not all situations allow trees to be used, pay special attention to the need for shallow water cover to hold fry. Fishiding products are just the answer to this dilema. Take a look and see why the only American made artificial fish habitat, made from reclaimed PVC is the answer to a green approach to fish habitat management. http:// www.fishiding.com

Vilas County may include structures in cost share program

By Ratchel White Of the Lakeland Times

Fish sticks aren’t just frozen food anymore. In areas where the technique is implemented, “Fish Sticks” refers to fallen trees arranged and utilized for fish habitat. The idea has gained local attention, especially because the structures are suspected to also reduce shoreline erosion.

Researchers studying shoreline restoration in Oneida and Vilas Counties are interested in possibly integrating the technique in their efforts. Vilas County Department of Land and Water Conservation has also eyeballed the technique as a potential candidate to include in their cost share program for landowners combating erosion.

Vilas County land conservation specialist Marquita Sheehan said that with so many lakes, people in this part of the state are likely to pick up on the technique.

Michael Meyer, lead research scientist on the above mentioned efforts, agrees. “Anything that increases people’s likelihood to catch fish is popular,” Meyer said.

And it does seem to be the case that the structures increase the amount of fish in lakes where they have been built. Thats according to Department of Natural Resources fisheries biologist Scott Toshner.

“People who fish in lakes and people who scuba dive or snorkel really like these things because they attract fish. That’s just the bottom line,” Toshner said.

Toshner has been involved with more than 20 “Fish Sticks” projects over the past four years. He has watched the interest in this method of improving lake health and habitat spread to other counties and even out of state. The idea for fish sticks was resurrected from a DNR study in the 1950’s.

The technique arranges entire trees, with their branches, in a criss-cross shape that resembles the letter A.  Typical structures use five tress and take up 25-50 feet of shoreline.

Fish Sticks are assembled on the ice so they will fall into place once the lake surface thaws. The structures are anchored to trees on the shoreline. They require a DNR permit and specialized equipment to build. Toshner estimated the cost of a project as roughly $25.00 per tree.

One project near Bayfield was scaled back because the structures were too near a beach at a public campground. However, Toshner said it was the only instance of controversy surrounding the structures.

Projects to put in structures have mainly been on private property and with landowner’s cooperation.

In all cases except for the above, Toshner said that response to the structures on lakes where they are put in is overwhelmingly positive. They have gained a reputation as improving fish habitat, though he said that the structures also improve turtle and other wildlife habitat.

In comparing the structures to fish cribs, Toshner indicated that they may provide a missing link in terms of fish habitat. “With the fish cribs, the one thing you kind of miss with them is the link between the near shore area where a lot of theses fish spawn and spend their lives as juveniles…[with fish sticks] the wood in this near shore area may be a missing link in terms of habitat in some of these lakes,” Toshner said.

In addition to improving habitat for lake critters, there is furthewr evidence that these structures may reduce soil erosion. However, the evidence remains annecdotal.

A UW-Steven’s Point study is attempting to confirm observations that the structures help prevent wave action and can build up eroded shoreline. Right now, it’s the growing interest in these structures that is is the most encouraging side effect, according to Toshner.

Lakes in Eau Claire, Douglas and Bayfield Counties currently have fish sticks structures, and Toshner said the forest service in the Michigan  Upper Penninsula and groups out of Minnesota have also expressed interest.

More interest leads to more awareness of the benefits of fish sticks projects, according to Toshner. The educational component of current projects cannot be overlooked, he said, especially for people who live out on the lakes.

“If they see this and they see that it’s a good thing, which is what we’re seeing, then they’re more apt to leave that tree in that fell along the shoreline instead of removing it,” Toshner said. “If people can see that trees in the water are a valuable resource, they’re less likely to remove a tree that might fall inj along their own shoreline.”