September 7th, 2010 by FISHBIO
Many rivers have had huge quantities of gravel extracted from active river channels, resulting in a net loss of gravel and drastically changing channel geomorphology. The construction of dams has eliminated the supply of coarse sediment to downstream river reaches. Gravel augmentation is a common strategy used in river restoration and improvement of salmon and steelhead spawning habitat.
Gravel augmentation in the California Central Valley is typically implemented in the late summer before the chinook fall-run migration begins. It is best to use native gravel that is mined in a nearby off-channel, since gravel from a different basin may lack the mineral composition that salmonids have imprinted on and can delay spawning use. Gravel is graded to optimal sizes and washed to reduce turbidity when placed in stream. Gravel may be placed into riffles by a front-end loader, as was done last week in the Merced River below Crocker-Huffman Diversion Dam. However, if access is limited it may be placed by alternative means, including helicopter, cable skyline, conveyor belt systems or injection into water pumped through a large diameter hose. Gravel can also be replenished by passive gravel augmentation, where gravel is added from a truck down the bank onto the stream and it mobilizes and shifts around when flows increase.
Photo source: FISHBIO
Posted in Delta Tributaries, Restoration, Salmon, Steelhead |
September 3rd, 2010 by FISHBIO
Despite their beauty, waterfalls can act as barriers to anadromous fishes, like salmon, that migrate upriver to spawn. The recent eruption of Eyjafjallajökull reminds us that Iceland, located over the Mid-Atlantic Ridge, remains geologically active. Due to the geology of the region, many of the rivers flow over waterfalls forming natural fish barriers. Iceland has almost 250 rivers and roughly 60 are used by Atlantic salmon. As with many European nations, adjacent property owners have rights to the majority of Icelandic rivers. The landowners are required by the government to form fishing associations that are responsible for managing and protecting the habitat, and that share the income derived from fishing access.
Nearly 600 miles of river habitat would have been off-limits to migratory fish had the people of Iceland not recognized the advantage of opening up fish habitat to create angling opportunities. Fish ladders have been constructed around many natural fish barriers and now provide access to 27% of the existing 2,175 miles of migratory fish habitat. The fish bypasses have been effective in increasing fishing opportunities and improving productivity of salmon. For example, only about a quarter-mile of the Langa River, meaning long river, was historically accessibly to salmon (photo above). Now, the river has gained 14 miles of salmon habitat and maintains an average annual catch of 1,407 salmon.
Photo source: FISHBIO
Posted in Angling, Iceland, Salmon, Vaki |
September 1st, 2010 by FISHBIO
Anglers around the world are faced with reduced freshwater fishing opportunities and access to rivers. Although many European countries posses “freedom to roam” policies and laws, landowners in some countries retain hunting and fishing rights. For example, everyone in Norway has the right to access and pass through private land, as long as they don’t pass next to a house or through cultivated land, however, the landowner holds the rights to freshwater fishing. Interestingly, fishing rights in Wales can be bought, sold and leased; therefore, a landowner can own the land while no longer possessing the fishing rights.
In the US most rivers are considered ‘navigable waterways’. Although many landowners may not be aware, the public has the right to use all running waters for activities such as boating, fishing, and hiking along the banks. The riverbeds and banks up to the ordinary high water line are considered public land (Frank 1983). Despite the public right to fish a navigable waterway, there may not be public access to get to the river, since private property rights protect landowners from trespass on uplands.
We took this picture in Iceland this past week where an angler at first appeared defiant of the rules. However, this angler, like most in Iceland, has paid between 300-500 USD for the privilege of fishing this stream for a day. Landowners of each watershed form associations to manage fishing access to the rivers. The fishing associations offer the right to fish each river and determine the maximum number of rods per day for each reach. The best salmon rivers can cost 1,000-1,500 USD per day for a single rod, but that usually includes a fishing guide, transportation, food and accommodations. Trout fishing is becoming more popular and can be accessed for 40-310 USD for one rod per day. The Icelandic government has few laws for salmon fishing, but the fishing associations determine additional regulations such as catch and release, fishing hours, and gear type.
Photo source: FISHBIO
Posted in Angling, Iceland, Vaki |
August 30th, 2010 by FISHBIO
During a recent visit to Iceland we were amazed by the limited number of freshwater fish species present on the island (7 species). There are only five native freshwater species and all are diadromous (use both marine and freshwater habitats during their life cycle). Atlantic salmon (Salmo salar), Arctic char (Salvelinus alpinus), and brown trout (Salmo trutta) live in the ocean as adults and migrate upriver to breed in fresh water (anadromous). Three-spined stickleback (Gasterosteus aculeatus) and European eel (Anguilla anguilla) are also native and live primarily in freshwater rivers, but migrate out to brackish estuaries or the sea to spawn (catadromous). Two non-native fish can also be found in Iceland’s rivers and lakes. Rainbow trout (Oncorhynchus mykiss) are bred in hatcheries and planted for sportfishing but do not reproduce in the wild. Occasionally humpback (pink) salmon (Oncorhynchus gorbuscha) are found on the island, but they are presumed to be strays from Russia.
Fisheries biologists in the Western U.S. are faced with much more diversity, with 58 species of freshwater fish found in the California Delta (more than half non-native) and 60 species in the Columbia Basin (nearly 40 percent non-native). Iceland maintains a strict disinfection policy towards tackle and waders imported by visiting anglers to prevent the introduction of diseases and undesirable species.
Photo source: FISHBIO
Posted in Iceland, Other Fish Species, Vaki |
August 27th, 2010 by FISHBIO
While kayaking a Northern California river this week a tangle of fishing line above the river caught our eye. Imagine our surprise when we got close enough and realized it was a bat (Myotis sp.) with a fishing hook in its mouth - and it was still alive. The hook, a bead head Hare’s Ear nymph, was probably nabbed by the bat after a fly fisher lost it in the tree. We were able to retrieve the bat from the tree and remove the hook from its mouth. As you can see from the video the bat was able to fly off in good condition. The Hare’s Ear was added to our collection.
Photo source: FISHBIO
Posted in Wildlife |
August 26th, 2010 by FISHBIO
White Catfish (Ameiurus catus), indigenous to the East Coast, were first planted in 1871 into the San Joaquin River at Stockton, by the California Fish Commission to provide recreation and food. As often occurs when non-native fish are introduced, the population exploded and a commercial fishery initiated. Annual commercial catch in the Delta exceeded 1 million lbs by the early 1900s and continued until 1941 when restrictions were initiated to protect recreational fishing.
A recent 7-year study (Feyrer and Healey 2003) demonstrated that white catfish are the 3rd most abundant fish species in the south Delta, behind bluegill and redear sunfish. According to creel surveys conducted by the Department of Fish and Game, catfish are the second most targeted species in the San Joaquin River with over 50,000 caught annually. Striped bass are the most targeted fish species.
Photo source: FISHBIO
Posted in Angling, Other Fish Species |
August 25th, 2010 by FISHBIO
A visit to the Kori no Suizokukan (Ice Aquarium) in northeastern Japan is a chilling experience. Frozen bodies are trapped mid-swim in their icy blue graves, while children in parkas gaze on. Spending a few moments in a -5°F aquarium is one way to beat the summer heat. Tourists wander through the icy columns of crabs, fish and octopuses, 450 specimens in all, that have been flash frozen to preserve their life-like forms. You can take home a souvenir for family and friends (”omiyage”) in the form of an action figure or bottle of saki frozen in ice, although it is likely to melt on the way home.
Photo source: CNET
Posted in Miscellaneous |
August 23rd, 2010 by FISHBIO
If you haven’t heard yet, we are being overrun by alien invaders! No, not little green men from space, but tiny gastropods known as New Zealand mudsnails (Potamopyrgus antipodarum). These tiny freshwater snails (pictured below on the left) were first detected in the United States in the Snake River in 1987 and have since spread throughout the Western United States. It’s not clear how they were first introduced, but they most likely hitched a ride on the wading boot of some unsuspecting angler.
New Zealand mudsnails are problematic since they disrupt the food chain by outcompeting native snails, like the pond snails pictured on the right (Lymneae sp.), and other aquatic invertebrates, leading to sharp declines in native populations. This in turn can negatively affect fish populations, by replacing the native prey with a less nutritional source. The mudsnails pass through fish guts undigested, without providing any nutritional value. With no natural predators, like the trematode parasites found in their native ecosystem, their populations have been rapidly expanding. Each female can produce approximately 230 young per year, and the species can reach concentrations above 500,000 per square meter. The tiny snails are effective at hitching a ride on fishing gear and can survive up to 30 days out of water thanks to their ability to seal their operculum. Many resource agencies have initiated educational campaigns to control the spread of mudsnails, such as California Department of Fish and Game’s “How to Prevent the Spread of New Zealand Mudsnails through Field Gear.”
Photo source: FISHBIO
Posted in invasive species |
August 20th, 2010 by FISHBIO
A fly fisherman’s soul may be one with nature but their sole may not. The felt-sole of fishermen’s wading boots are a vector for the spread of many non-native invasive species such as New Zealand mudsnails (Potamopyrgus antipodarum) and didymo (Didymosphenia geminata) an algae also known as rock snot. Many resource agencies have implemented outreach campaigns and taken control measures aimed at preventing the spread hitchhiking invaders, but some states have taken further precautions.
There is a movement afoot (pun intended) to ban the sponge-like felt-soled boots from use and recently Alaska and Vermont have approved such bans. Many fishermen and fisheries biologists prefer felt-soled boots because of their ability to grip slippery rocks. The best alternative to felt-soled boots are the studded, rubber-soled boots, which are easier to clean and disinfect after use and still provide adequate traction. Here are a few options for cleaning your gear, courtesy of Oregon State.
Photo source: FISHBIO
Posted in Angling, invasive species |
