To properly descend a fish with a lip clamp or inverted hook, attach the descending device and weights to a heavy-duty rod and reel that is designated for descending or use a rope to handline the device and weights down and back up. There are various types of descending devices but the most common are lip clamps, inverted hooks and fish elevators. It is important to find the device that works best for you.īefore you go fishing, be sure to have your selected descending device ready for use. With the right tool and the right technique, all anglers should properly descend or vent a fish and give them a better chance at survival. When a fish survives release, it has another opportunity to reproduce and grow the population, leading to more fishing opportunities in the future.ĭescending devices are tools with weights that attach to a fish and help take the fish back to the appropriate depth. Signs of barotrauma include bloated belly, distended intestines, stomach coming out of the mouth and bulging eyes.
These injuries can be fatal to the fish unless intervention occurs through the use of descending devices or venting tools. Signs of barotrauma include the stomach coming out of the mouth, bloated belly, distended intestines and bulging eyes. Barotrauma, or injuries caused by pressure changes, occur when fish are rapidly brought to the surface from depths 50 feet or greater. Such information can help engineers focus on problem areas when designing new turbine runners to be more fish-friendly than existing units.If you’re fishing for reef fish this season, be sure to look for signs of barotrauma and be prepared to act. The majority of pressure nadirs occurred immediately below the runner blades, with the lowest values in the gap at the blade tips and just below the leading edge of the blades. The estimated rates of mortal injury increased from 0.3% to 1.7% as discharge through the turbine increased from 334 to 564 m 3/s for fish assumed to be acclimated to a depth of 5 m. Following the description of the general method, application of the BioPA to estimate the probability of mortal injury from exposure to rapid decompression is illustrated using a Kaplan hydro turbine at the John Day Dam on the Columbia River in the Pacific Northwest region of the USA. In this paper, the BioPA method is applied to estimate barotrauma induced mortal injury rates for Chinook salmon exposed to rapid pressure changes in Kaplan-type hydro turbines. By comparing the values of the indicators from various turbine designs, engineers and biologists can identify the more-promising designs and operating conditions to minimize hydraulic conditions hazardous to passing fish. If the relationship between the dose of an injury mechanism (stressor) and frequency of injury (dose–response) is known from laboratory or field studies, the likelihood of fish injury for a turbine design can be computed from the performance indicator. Each performance indicator is a measure of the probability of exposure to a certain dose of an injury mechanism. Using this method, a suite of biological performance indicators is computed based on simulated data from a computational fluid dynamics (CFD) model of a proposed hydro turbine design.
We introduce a method for hydro turbine biological performance assessment (BioPA) to bridge the gap between field and laboratory studies on fish injury and turbine engineering design.