Effects of addition of tilapia on the abundance of periphyton in freshwater prawn culture ponds with periphyton substrates

Abstract

A $2-million habitat restoration project on Belle Isle is expected to further the comeback story of fish on the Detroit River and make Detroit?s island park a more desirable destination for anglers.

Keith Flournoy, Belle Isle park manager for the city, called the improvements ?wonderful.?

?Just the aesthetics of it look great,? he said. ?And what it does for habitat, for the fish to thrive in this area; the opportunities for fishermen to have a better fishing experience both in the Detroit River and on Belle Isle … I think it?s money well-spent.?

Belle Isle was on display last weekend for the annual Chevrolet Detroit Belle Isle Grand Prix and will take center stage again next weekend with the two-day Orion Music + More festival featuring metal giant Metallica. But the habitat enhancements are occurring on the little-trafficked east side of the island, usually left to birds, frogs, turtles and snakes. More habitat articles at fishiding.com

A $1.5-million portion of the project is transforming the Blue Heron Lagoon, a 41-acre wetland on the island?s east end that for decades has featured a small, pump-fed lake closed to the river. The lagoon is now open to allow the river to flow through. A new pedestrian bridge spans the water opening.

The lagoon now better provides areas where baby fish, known as fry, can hide and develop during a crucial period when they are most vulnerable to predators, said David Howell, chairman of Friends of the Detroit River, a nonprofit that helped lead efforts on the Belle Isle projects. Dredging over the years to improve freighter shipping on the river destroyed many of the gravelly bottom areas fish like for spawning, he noted.

?If they did spawn, the eggs or little fish would just get washed away. There was no safe harbor,? Howell said. ?This is a place for fry to go and grow and return to the river.?

Some deep holes were excavated in the lagoon to vary water depths, said the Friends? Sam Lovall, project manager on the Belle Isle habitat restoration.

?It?s really been an attraction to fish,? he said.

A peninsula constructed in the lagoon is currently being planted with a variety of submerged and emerged plants, further improving habitat.

?The whole point is diversity in the biosystem ? more fish, more birds, the snakes, the turtles,? Lovall said. ?All of them living together is what makes a healthy community of wildlife.?

Southwest of the Blue Heron Lagoon, at the South Fishing Pier, a series of breakwaters now slows the current between the pier and land, protecting small and large fish alike from both the river flows and large freighters? wakes, Lovall said. More plantings and water depth variances further enhance the fish habitat.

?It?s a nice fishing pier, but fishermen didn?t typically have a lot of luck fishing there because it?s right in the middle of the current,? Howell said. ?There?s no place for the fish to gather or sort of rest. The fish just get pushed on down the river. The South Fishing Pier created some shelter and rest spots.?

The project works in concert with spawning reefs constructed in the river near Belle Isle in recent years, which has led to a comeback in fish species including the threatened lake sturgeon, Michigan?s oldest and largest fish, as well as whitefish, Howell said.

The project is funded through the Great Lakes Restoration Initiative, a federal grant program designed to address areas of concern in the Great Lakes region. That includes the Detroit River, with its long history of industrial pollution and aquatic habitat loss.

?About 97% of coastal wetlands on the Detroit River are gone; the original, coastal wetlands,? Howell said.

?Efforts like these and others up and down the river are designed to protect the remaining 3% and add to it.?

Texas Parks and Wildlife Department biologist Wes Studder aids in transferring a net full of the more than 100,000 striper fingerlings stocked at Possum Kingdom Lake May 30. The stocking was done following a work project which sank cedars and brush piles to increase fish habitat in the lake. (Sarah Howard)

In an effort to continue to increase the fish population at Possum Kingdom Lake, Texas Parks and Wildlife Department stocked 100,000 striper fingerlings May 30. The fish arrived from the new TPWD East Texas fish hatchery in Jasper. They were then transported by boat from North D&D to deeper water before being released into the lake. “We use the deep water transfer to help avoid predators that are usually close to the shoreline,” said Steven Hise, TPWD staff member charged with the job of transferring the fish. According to Wes Studder, TPWD senior technician, the stocking was done following a work project which sank cedars and brush piles to increase fish habitat in the lake. “The new brush piles will provide shelter for the new fish,” he said. “It is great to have a group of people to work with on projects like this.” TPWD is working in conjunction with Hell’s Gate Bass Club on projects to improve the lake. Plans to coordinate with the club were made after an April HGBC meeting where members voted to establish a chapter of Friends of Reservoirs. The program will enable the club to obtain grants and donations for projects done in conjunction with TPWD. TWPD also plans to start 60 small colonies of American pond weed and water willow in the Cedar Creek area of the lake. “We have plans to return to the lake in June to establish vegetation habitats,” said Studder. “It will give us another chance to work with the Hell’s Gate Bass Club.” Dropping water levels and the age of the reservoir have resulted in fewer habitats and less natural plant growth that acts as a refuge for younger fish. To battle this, TPWD began a habitat enhancement project. Its goal is to create natural and artificial habitats, as well as re-introduce aquatic vegetation into the lake creating safe places for young fish. By Sarah Howard. More habitat articles at fishiding.com

AGFC projects under way on riverbed, overlook

“Fish habitat” is a
simple term. We can easily
imagine a fish languishing
under a log or in
a kelp forest, and we can
picture a school of forage
fish zipping through the
water column. We can
also grasp that the preferred
space for many species might change as the seasons change and
the years pass by. But the rest of the story is not quite so simple,
mostly because life is more complicated and knowledge is often
limited. This month’s “Fish Habitat Connections” seeks to demystify
those details so we can appreciate the intricacies in the
fish habitat world and become more emboldened to serve fish
not just as a meal but as they deserve.
Let’s begin with semantics. Each fish occupies its preferred
niche in the ecosystem. The environmental conditions of that
space define the fish’s preference at each life stage—water
temperature, depth, salinity, flow, bottom type, prey availability                                                annual cycles, and much more. It is important for us
as professionals to place those variables in proper context so
that individual fish can survive, fish stocks can flourish, fishery
management can succeed, and society can benefit from our nation’s
waters.
That simplistic summary reflects our hopes, which are
complicated by the reality that we know very little about our
most basic habitat questions. With luck, we know where fish
live throughout their life cycles. But oft times we have few
insights into the shifting preferences of each life stage. Even
that knowledge is elusive unless we have close observations
from multidecadal stock assessments or the insights offered
by a healthy fishery. Almost universally, we rarely understand
the relationships between fish and their habitat.

If a wetland is
dredged, how will the local fish populations change over the
short and long term? If a dam is breached, will the new hydrological
regime support native species or invite invasive species?
If an acre is protected or restored, how will the population respond?
Will harvests increase?
These issues read like the final program at many an American
Fisheries Society (AFS) conference. They have vexed us
as a profession for decades. We must manage fisheries with the
best available information, scant as it might be. And we must
identify our primary needs so that gaps are addressed.
COLUMN
Fish Habitat Connections There is also the still-new concept of ecosystem-based approaches.
Habitat must be an essential variable in stock assessments,
but those analyses must be conducted with an ecosystem
in mind. Those perspectives can be as important as data. Without
that challenge, we won’t even know we have a data gap.
Considering how complex this simple topic can be, and
how it reflects human pressures from our coasts to the mountains,
it is probably no surprise that we continue to lose habitat
function at alarming rates. Along our oceans, marine and estuarine
wetland loss was three times higher between 2004 and
2009 than in the previous 5 years (Stedman and Dahl 2008;
Dahl 2011). Inland wetland loss is not as severe, but hundreds of
rivers representing thousands of river miles are compromised by
blockages that prevent fish movement upstream or downstream.
The first-ever national fish habitat assessment found that 53%
of our estuaries are at high or very high risk of habitat degradation
(National Fish Habitat Board 2010). Given those numbers,
it is unfortunate that those places provide vital nursery habitats
for many of our favorite fish.
As fishery professionals from all disciplines, our assignment
is to combine our skills to protect important habitats and
restore those that are degraded. Our mission will be slightly
less daunting if we and our partners can set a pace to match
the steady pressure of human population growth and looming
challenges such as climate change. AFS represents an incredible
knowledge base. If anyone can analyze our habitat knowledge,
fill our priority gaps, apply lessons learned, and improve habitats
for the benefit of all, it is us.

More habitat articles at fishiding.com
Next month we will shift from the nuances of semantics
to the harsh realities of the challenge before us. It is imperative
that we engage now! Economic and ecological facts urge AFS,
its units, each of us, and our home institutions to accept the challenge.
We will explain the opportunities before us and how our
collective skills are needed for success.
REFERENCES
Dahl, T.E. 2011. Status and trends of wetlands in the conterminous
United States 2004-2009. U.S. Department of the Interior, Fish
and Wildlife Service, Washington, D.C. 108 pp.
National Fish Habitat Board. 2010. Through a fish’s eye: the status of
fish habitats in the United States 2010. Association of Fish and
Wildlife Agencies, Washington, D.C. 68 pp.
Stedman, S., and T. E. Dahl. 2008. Status and trends of wetlands in the
coastal watersheds of the Eastern United States 1998 to 2004. National
Oceanic and Atmospheric Administration, National Marine
Fisheries Service, and U.S. Department of the Interior, Fish and
Wildlife Service, Washington, D.C. 32 pp.