FISHBIO: Fisheries research, monitoring, and conservation

February 22, 2013

Fishing in Mekong cities looks a bit different than catching fish in rural villages. During a recent visit to Cambodia to train local researchers (see Makeshift lab), FISHBIO staff spotted some anglers trying their luck along the banks of the Mekong River in the capital city of Phnom Penh. To our surprise, one was ready to slip a cockroach onto his hook to lure ‘em in. Although other animals ususally come to mind when we think of “bait” in the U.S. (see Baitfish), the resourceful use of this hardy pest makes sense in an urban hub of 1.5 million people. Since fish of any size can be used for food, why waste one for bait when there are plenty of scurrying insects that no one would miss? If you’re not squeamish, this looks like more fun than hiring an exterminator.

Tags: Angling, bait, Cambodia, fishing, Mekong River, Relevant Mekong Links

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Angling, Mekong Basin

Need a lift?

January 11, 2013

Lift nets (called Gadung in Lao) are one of the most common types of fishing gear used in Southeast Asia. The gear consists of a fine net suspended by four corners to a wooden frame (see Cantilever contraption). Fishers leave the net in the water for some time, then slowly lift it, trapping any fishes and aquatic animals swimming above the net. A small, hand-held version is commonly used in quiet water along riverbanks, in canals, and in flood plains, and is the gear that women fishers most frequently use. The lift nets in these pictures operate in the canal of Thatluang Marsh in the Lao capital of Vientiane. FISHBIO staff working on our international conservation projects in Lao PDR interviewed part-time women anglers about their fishing practices in this area. The primary fishing gear used in this marsh includes cast nets, gill nets, hook and line, fish traps, and lift nets. Fish typically caught with lift nets include three spot gourami (Trichogaster trichopterus), snakeskin gourami(Trichogaster pectoralis), climbing perch (Anabus testudineus), pale rasbora (Rasbora aurotaenia), Nile tilapia (Oreochromis niloticus), shrimps, and other aquatic animals. The area currently available for fishing in the marsh is smaller than it was five years ago due to a land concession to foreign investors to build a Chinatown.

Tags: Angling, fishing, Lao PDR (Laos), Laos, Mekong fishing, Relevant Mekong Links, Subsistence fishing

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Angling

Gone fishin’

July 16, 2012

It’s a cool morning and the sun is just peaking up over the horizon. You pull the truck up to the river near your favorite fishing hole, grab your fishing pole and head down to the water. For the next couple hours, there won’t be a care in the world. Just you, the water, and hopefully a couple fish on the other end of the line. But of course, you’re not the only one out there on the river enjoying the ‘solitude’. According to an annual Special Report On Fishing and Boating released by the Recreational Boating & Fishing Foundation (RBFF) and the Outdoor Foundation, 46.2 million Americans (16.2% of Americans older than 6) participated in fishing in 2011. Fishing continues to be the most popular recreational activity in the country and according to the report, anglers made a total of 840 million fishing trips last year (an average 18.2 days per angler) and included individuals from all walks of life (Figure 1). Fishing is one of the great American pastimes that has become more than just a father-son tradition. It doesn’t matter if you are rich or poor, young or old, or male or female, it seems that everyone is getting into fishing. Nearly everyone, that is. Notably, the results of the study indicate that anglers are predominantly Caucasian, with Hispanics and African Americans making up only 5.4% and 5.5% of anglers, respectively.

Despite being the most popular recreational activity in the U.S., there has been a decreasing trend in the number of participants over time. From 1991 to 2006, the number of people older than 16 that participated in fishing fell from 35.6 million to 30.0 million. Likewise, between 2006 and 2011 the number of anglers ages 6 and up fell by 3.5 million. The Hispanic population is the largest minority in the U.S. and the report indicates that attracting more minorities, such as Hispanics, to the sport of fishing is critical to increasing overall participation by Americans.

Figure 1. Angler demographics for 2011 presented in the 2012 Special Report on Boating and Fishing.

In spite of this decrease in participation, the amount of money spent on fishing has risen over the past two decades, from $24 billion in 1991 to $42 billion in 2006 (accounting for inflation that was an increase of about $6.5 billion). One of the biggest reasons for the increase is due to the amount of money that is spent on equipment. Anglers’ equipment costs have jumped from $9.4 billion in 1991 (about $13.9 billion in 2006 dollars) to $18.8 billion in 2006. Although it’s unclear why the expenses have increased, one can speculate that advancements in technology have played a factor.

In California, the price of a fishing license has been increasing faster than the rate of inflation. In 1996, a California resident fishing license cost $24.50 ($35.15 in 2012 dollars), but today the price of a fishing license is $41.50. Like most things, the price will continue to increase and some will be deterred from the sport while others will continue their passion. Whether you are trying to escape the daily grind for a few hours, love the taste of fish, relish the thrill of the catch or just enjoy being outdoors, fishing has become a sport for the masses.

Tags: Recreational fishing

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Angling, Commercial Fishery, Research

Are your fish safe to eat?

June 11, 2012

Contamination of fish is becoming a growing concern for many recreational and commercial fishermen. Recently, results from the first statewide study of contaminants in fish caught off the California coast revealed high levels of methylmercury, a toxin that damages the central nervous system, in more than one-third of the locations sampled. High levels of mercury, greater than 0.44 parts-per-million (ppm), were detected in fish tissue at 25 of the 68 locations sampled (SWAMP 2012). However, location was not the key driver, rather the main factor linked to contamination level was the type of fish. Older, predatory fish such as sharks and some forms of rockfish were found to have the highest levels of mercury. The North Coast (from the Oregon border to Point Reyes) had the highest percentage of locations with at least one species above 0.44 ppm of mercury (11 out of 15, or 73%). The Central Coast (from Point Reyes south to Point Conception) had the second highest percentage (10 of 26, or 38%) while the South Coast (from Point Conception south to the Mexican border) had the lowest percentage of locations above 0.44 ppm of mercury (4 of 27, or 15%) (SWAMP 2012). All of the species with high concentrations of mercury were high-level predators, which can be explained through bioaccumulation of mercury up the food chain.

Mercury is released from ores, minerals and fossil fuels into the atmosphere where it can circulate through out the world and accumulate in living organisms in the water and on land. These releases are through natural events or during human activities. Among the largest sources of mercury emissions in the U.S. are coal power plants and mining operations (especially gold mining). A potentially growing source of mercury is disposable products such as compact fluorescent light bulbs and electronic devices, which both contain mercury. The mercury eventually leaks into the atmosphere when the products are crushed in a landfill.

Polychlorinated biphenyls (PCBs) were the only other contaminant detected in fish tissues at concentrations that pose potential health concerns to consumers of fish caught in coastal California waters. Far fewer locations fell into the high contamination category for PCBs (5 of 68, or 7%) than for methylmercury. PCBs have been banned in North America since the 1970s when they were widely used as insulation in electrical equipment, but they are still showing up in coastal California waters. PCBs are insoluble in water and not readily excreted by marine organisms; as a result they are often passed up the food chain. The results from the statewide survey will be used to prioritize coastal areas that are in need of cleanup or identify areas that need continued monitoring.

The Southern California coast may have had the lowest percentage of locations with high contamination of mercury, but a new study has recently found elevated levels of radioactivity in blue fin tuna off the coast of San Diego. This radiation is directly linked to the nuclear power plant disaster in Japan following the March 2011 earthquake. Blue fin tuna are a highly migratory fish traveling across the Pacific Ocean from Japan all the way to Southern California, but researchers were shocked to learn the fish were not able to flush out all of the contamination from their system during their journey across the ocean. This summer, researchers plan to repeat the study using a larger sample size to determine just how radioactivity may affect tuna populations. Scientists are also interested in tracking other migratory species for contamination such as sharks, sea turtles and seabirds.

Tags: mercury pollution

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Angling, Other Fish Species

Fish and Game Commission denies CDFG’s proposed changes to striped bass angling regulations

February 3, 2012

Yesterday, by unanimous decision, the California Fish and Game Commission rejected proposed changes to striped bass regulations. To reduce predation on native salmonids and Delta smelt, the California Department of Fish and Game (CDFG) proposed decreasing size restrictions and increasing bag limits of striped bass. The sport fishing regulation changes were intended to reduce the size and abundance of striped bass in the Delta and Central Valley tributaries, and were proposed as part of a settlement agreement to a lawsuit by the Coalition for a Sustainable Delta. No word yet on how this will impact the original lawsuit, but, we think it’s fair to say that this issue is far from over.

Tags: regulations, striped bass

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Angling, Underwater Photography

To barb or not to barb…

August 5, 2011

On a recent dive in a Sierra Nevada lake we spotted this unlucky fish that had been hooked and entangled around the dock pillar. This got us thinking about the potential mortality of fish once they’re caught by an angler and the effect of different angler gear on fish survival. A review of previous studies on the hooking mortality of non-anadromous trout by Schill and Scarpella (1997) revealed some surprising results. By analyzing data from past studies they concluded that there is no significant difference in the hooking mortality of trout caught and released using barbless hooks and barbed hooks. Taylor and Barnhart (1996) found no significant difference in hooking mortality of summer steelhead between single and treble hooks, but they did find a positive correlation of increasing mortality with increasing water temperature. Post-hooking mortality of steelhead caught and release in water below 64.4°F (18°C) was less than 5%, whereas fish captured in water 71.6-77°F (22-25°C) had a hooking mortality of 17-34%. A recent study of hook type on an Alaskan rainbow trout catch-and-release fishery found that barbed “J” hooks took longer to remove and injury rates were higher than for barbless (Meka 2004). Angler gear selection and fishing regulations will no doubt continue to be a hot button issue, but when it comes to using barbless hooks, even if they don’t significantly increase survival, it sure makes fishing more sporting.

Tags: hooking mortality, survival rates

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Angling, Steelhead, Telemetry

Catch and release, again

November 4, 2010

As explained in our recent post Fisheries Outpatient Center, we are currently conducting a study of trout (Oncorhynchus mykiss) movements in a central valley watershed. We expected that we would be able to track fish throughout the watershed, but recapturing a tagged fish was unexpected. This female O. mykiss was first caught angling on March 23, 2010. It was approximately 20 inches (505 mm) in length and appeared to be post-spawn, due to the eroded caudal fin and lean appearance. We surgically implanted an acoustic transmitter (HTI LX tag) and released the fish in the same location where she was caught. Since her release we have been tracking her location using fixed and mobile hydrophone receivers. During the last 7 months she has remained within one third of a river mile (570 meters) of the site where she was originally captured and released. To our surprise, while out angling this fall for additional O. mykiss to tag, we managed to recapture this same fish (October 20, 2010). The incision was completely healed but, interestingly, a suture remained loosely attached (sutures usually dissolve within 90 days). The fish was measured and released, again.

Video source: FISHBIO

Tags: acoustic transmitter, hti, Oncorhynchus mykiss, trout

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Angling, Salmon

A year in freshwater

October 22, 2010

chinook-yearling

We caught this yearling Chinook salmon (Oncorhynchus tshawytscha) last Friday while angling for rainbow trout/steelhead (O. mykiss) as part of an acoustic tracking study to evaluate O. mykiss migration characteristics. The salmon yearling, about 6 inches in length (162mm), hatched last winter at the same time as the young-of-the-year migrants, which migrated out as fry, parr, and smolts between January and May. In California, Chinook populations are considered “ocean-type”, which means that the majority of juveniles migrate to the ocean during their first few months of life. “Stream-type” Chinook spend at least their first year in freshwater and are more common in northern populations. It is not known exactly what percentage of California Chinook salmon rear for a full year in freshwater before migrating to the ocean, but it is believed to be small, probably less than 1 or 2 percent of all migrants.

forklength

Outmigrating juvenile salmon are monitored on the Tuolumne river each winter and spring using rotary screw traps. In general, during the early winter salmon are captured as small, recently emerged fry (less than 50mm in length) and in the spring they are captured as outmigrating smolts that have reared for a few months in the river. Last winter, between January and mid-March at least 45 salmon were caught in the trap that were notably larger than the majority of juvenile salmon (fry) captured during that period. The graph above shows the daily average forklengths of salmon caught in the trap and depicts a few days in the winter of higher-than-normal average forklength, indicating that some salmon on the Tuolumne migrate out as yearlings.

Photo source: FISHBIO

Tags: fry, ocean-type, Oncorhynchus tshawytscha, parr, salmon, smolt, Stream-type, yearling

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Angling, Iceland, Salmon, Vaki Riverwatcher

Roadblock

September 3, 2010

iceland-waterfall

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.

iceland-lnga-river-fish-ladder

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

Tags: anadromous fish barrier, Iceland

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Angling, Iceland

Anyway you read it, no fishing!

September 1, 2010

no-fishing

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

Tags: Angling, Fishing access, navigable waterways, Private fishing rights