Four years after California's largest dam removal project, how are the fish doing?

MAY 27, 2019

by Paul Rogers, The Mercury News

Four years ago, construction crews with huge jackhammers tore apart a 10-story concrete dam in the wooded canyons of the Carmel River, between the Big Sur hills and the beach front town of Carmel.

The destruction of the San Clemente Dam, which had blocked the river since 1921, remains the largest dam removal project in California history. It's still early, but one of the main goals of the project seems to be on track: The river is becoming wilder, and struggling fish populations are rebounding.

"We don't want to do the touchdown dance yet, but so far things are looking good," said Tommy Williams, a biologist with the National Oceanic and Atmospheric Administration, who has monitored the Carmel River's recovery. "It's just amazing how fast these systems come back. Everything is playing out like we thought."

Removal of the century-old dam is being watched closely around the country as a potential model for how to demolish other aging, dangerous and obsolete dams and restore rivers to a natural state not seen in generations.

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A Fish's Personality May Determine How It Is Captured

ScienceDaily (Oct. 4, 2011) — A fish's personality may determine how it is captured. This association between personality difference and capture-technique could have significant evolutionary and ecological consequences for affected fish populations, as well as for the quality of fisheries.

Anglers fishing near rocky outcrops or in areas of water with submerged vegetation may be more likely to catch timid fish, while those fishing in open water may be more likely to reel in bolder fish, according to new research conducted at Queen's University Biological Station.

"Boldness -- the tendency of an individual to take risks -- is one personality trait of considerable interest to behavioural biologists," explains lead author Alexander Wilson, a visiting biologist from Carleton University. "Ours is the first study to have characterized a relationship between capture technique and individual boldness in a wild population of fish."

The researchers examined the personalities of bluegill sunfish caught by two different capture techniques -- angling (a hook attached to a fishing line) and beach seining (a long net that is dragged through water to encircle fish).

Fish caught in the wild by angling were more timid than fish captured in the wild using a seine net. However, when a group of fish captured by seine net was then released in a large outdoor pool and angled for, it was the bold individuals who were most often caught in the open.

According to Dr. Wilson, these findings make ecological sense. Despite spending equal times angling in open water areas and in areas with refuge, the researcher caught more fish in the areas with refuge -- a habitat that appeals more to timid fish. On the other hand, beach seining or angling in open water are both capture techniques that are more likely to target bolder, risk-taking fish.

http://www.sciencedaily.com/releases/2011/10/111004151635.htm

The fish making offshore oil platforms their home

Could these man-made structures be used as reef habitat too?
September 2011: Oil and gas platforms could be serving as beneficial habitats for commercially important fish populations such as cod and haddock, a marine ecologist has told the World Conference on Marine Biodiversity being held in Aberdeen.

If adequate knowledge is to be gained from the existing offshore platforms, there may also be potential for man-made structures like offshore platforms and installations for renewable energy to be used as reef habitat, Dr Toyonobu Fujii of the University of Aberdeen's Ocean Lab said.

The researcher has been analysing long-term bottom trawl survey data of fish distributions in relation to the installation history of offshore oil and gas platforms in the North Sea.

Commercially important species gather in numbers‘There are currently no fewer than 500 offshore installations extracting oil and gas primarily from the continental shelf in the North Sea and, since the first installation, more and more researchers have been aware that a variety of commercially important fish species such as cod, haddock and saithe gather in substantial numbers around these artificial structures,' said Dr Fujji.

‘Currently, all the offshore platforms and the safety zones around these platforms, combined, account for only 0.08 per cent of the surface area of the North Sea. However, the proportion of fish abundance estimated to aggregate around these structures was much higher than the surface area alone would suggest.

‘We still don't know exactly why they are gathering there. It could be because there are more feeding opportunities or possibly because they provide places for them to shelter or hide.

Could be used as a nursery or breeding ground‘But if they are using these habitats as nursery or spawning grounds then the implications of the physical presence of these structures could be important since such biological mechanisms strongly drive the future population dynamics of the fish.'

Dr Fujii says more research is needed into the causes and seasonal nature of such phenomena in association with artificial structures. He also wants to explore whether other fish species such as flatfish or pelagic fish such as mackerel show similar trends and are attracted to these sites.

‘Given the magnitude of scales at which fish movement could be influenced by the offshore platforms, such knowledge will be of critical importance for future spatial management of seafloor as well as sustainable fisheries management, perhaps this is even more pertinent now with the expected expansion of offshore renewable energy developments.'

http://www.wildlifeextra.com/go/news/offshore-platform-fish.html