IMPORTANT
Descending Devices REQUIRED
Beginning in 2024, a descending device must be carried aboard and available for immediate use on any vessel taking or possessing any species of federal groundfish (CCR, Title 14, § 27.20 (b)(2)). If you are using a separate rod to descend fish it can only have a descending device and no hooks. There are some descending devices that can work in-line with hooks on your fishing rod. These descending devices can be attached to your fishing line, above or below the hooks, as long as you are still abiding by the two hooks and one line the regulation calls for.
Get "Hooked" on Descending - Types of Descending Devices
There are many different types of descending devices, which can be made at home or purchased. This video on barotrauma explains different types of descending devices and how to use them:
Homemade Descenders
Here are just a few types of descending devices and how to operate them:
Milk Crate
Milk crates descenders can be constructed from a plastic crate, with a minimal weight (~5 lbs) attached around the opening and at least 60 ft of rope tied to the bottom. This device is inexpensive, easy to use, and multiple rockfish can be returned to depth at once. Simply place the rockfish in the crate, swiftly invert the crate while immersing it into the water and lower it steadily to return the rockfish to depth.
Wire Hanger Shepherd’s Crook
The wire hanger shepherd's crook is another kind of homemade descending device. You will need a wire hanger, a broom handle, a pair of pliers and a snap swivel. First cut off the hook of the wire hanger, straighten the wire, double over the hanger a third down its length, then wrap and bend a loop (use a broom handle for support) holding both sides with the pliers twist the two sides together for three turns to make a ridged loop to tie line to. Bend the short end into a shepherd’s crook providing space to hang the fish on. The long end is then doubled over three inches from the end and a snap swivel placed in the bend. With the pliers, twist the two ends of the wire together to secure the snap swivel and cut off excess wire. The device can then either be sprayed or dipped in rubber compound to prevent rust, or used as is and rinsed down and oiled after each day's use. Attach a weight to the bottom snap swivel that is sufficiently heavy to bring the fish down.
To release a fish, slide the shepherd's crook under the operculum being careful to avoid the gills or you can pierce the fish’s lower jaw. You can attach the wire hanger shepherd's crook descending devices to a spare, dedicated descending rod for easy access while fishing or use it on the rod you are fishing with by attaching it to the end of the line with the weight attached to the snap swivel on the long end.
Standard Wire Hanger Descender
With just a few simple items that can be found around the house - a wire hanger, cutting plyers, zip tie or fishing line, and a weight - you can create an easy-to-use descending device.
Click image to enlarge
Barbless Inverted Hook
Barbless inverted hooks are another kind of homemade descending device. Invert a barbless hook and tie a piece of monofilament line to the bend in the hook. Tie a loop at the top or tie the inverted hook directly to a swivel on a dedicated descending rod. Attach a weight to the bottom eye of the hook. With the bail on your reel open, quickly place the fish in the water and drop the line down to the appropriate depth. Swiftly jerk your rod to release the fish off the hook.
A best practice is to have your barbless inverted hook ready to go on a fishing pole that is not being used for fishing. This will allow quick transfer of the fish to the descending device, increasing its chance of survival.
Modified Hoop Net
Like the milk crate, altering a hoop net can create a homemade descending device used to get multiple rockfish returned to depth at once. Depending on the size of the rockfish you may need to add some weight to the bottom of the hoop net. To modify your hoop net into a descending device, remove the rope from the larger ring, flip the hoop upside down, and connect your line to the smaller ring of the hoop net. Before using, make sure the hoop net is safely tied to your vessel, free of knots, and readily accessible when fishing. Place the unwanted fish on the water’s surface and quickly place the net over the top of the fish or place the fish inside the hoop net and throw it over. Release the rope allowing the hoop net to push the fish back to the bottom while maintaining slack on the line.
Click image to enlarge
Commercially Available Descenders
The use of brand names or any listing of specific commercial products is solely for example purposes and does not imply endorsement by the California Department of Fish and Wildlife (CDFW) and is not exclusive of brands or products available for use as a descending device. If anyone would like their product listed as an example, please contact CDFW at AskMarine@wildlife.ca.gov.
Modified Fish Grip
With a few simple tools and supplies a fish grip can be modified into a homemade descending device. Cut the bungee off the fish grip and drill a hole in the top and bottom of the handle if they are not already there. Tie a small piece of line with a loop through each hole and put a rubber band or hair tie around the handle. The rubber band will need to be replaced regularly.
Attach one line with a loop to a separate fishing rod and a weight on the bottom loop. Clamp the device on the lower jaw of the fish. With the bail on your reel open, quickly place the fish in the water and drop the line down to the appropriate depth. Swiftly jerk your rod to open the jaws and release the fish.
SeaQualizer
The SeaQualizer attaches to the lower jaw and has a self-release mechanism. This device has a pressure pin built in that allows for automatic release at a specific depth. With three depth options, an angler can choose the depth of release. The standard model releases at 50, 100, or 150 feet. The deep model releases at 100, 200, or 300 feet. If you use a SeaQualizer make sure it is capable of returning a fish to your fishing depth. Attach a SeaQualizer to a second rod for a seamless transition from your fishing line to descending line.
The Shelton
The Shelton is a commercial descending device that can be used on a rod designated as a descending device or in line with your fishing gear, for ease of transition. The Shelton pierces the lower jaw through the soft membrane, sharp edge pointing down. When dropped to the appropriate depth, simply jerk the rod to release the fish.
The Promar Descending Device
The Promar Descending Device is a commercial descending device that can be used on a rod designated as a descending device or in line with your fishing gear, for ease of transition. The Promar pierces the lower jaw through the soft membrane, sharp edge pointing down. When dropped to the appropriate depth, simply jerk the rod to release the fish.
RokLees
The RokLees device attaches to the lower jaw of the fish, with the yellow pad placed under the lower jaw. Using a weight, the fish can be quickly lowered to depth and with a firm shake of the rod, the clamp will open, and the fish will be released.
Fishsaverpro
The Fishsaverpro is a commercial descending device that can be used on a separate rod. To use, attach the hook through the bottom lip. With the added weight, place the fish headfirst into the water. When dropped to appropriate depth, jerk the rod to release the fish.
Diamond Fish Saver Release Device
The Diamond Fish Saver Release Device is a commercial descending device that can be used on a separate rod. Pierce the lower jaw through the soft membrane, sharp edge pointing down. With the added weight, place the fish headfirst into the water. When dropped to appropriate depth, jerk the rod to release the fish.
SeaYa Later
The SeaYaLater is a commercial descending device that can be used on a separate rod. Pierce the lower jaw through the soft membrane, with the sharp edge pointed up. The SeaYa Later is engineered so the buoyancy of the fish will cause the descending device to invert and pull the fish down once it’s in the water. With the added weight, place the fish headfirst into the water. When dropped to appropriate depth, jerk the rod to release the fish.
Blacktips
Blacktips are no longer manufactured but still worth mentioning, as a well-loved descending device within the fishing community. The Blacktip is a spring-loaded jaw clamp. Like other commercial devices, the fish is released when the device hits the bottom or is given a swift jerk.
What is Barotrauma?
CDFW photos
Figure 1. Physiological changes occur when a rockfish is brought up to the surface. Click image to enlarge
Barotrauma is a pressure related injury that often occurs when fishing for rockfish. Rockfish have a specialized gas-filled organ known as the swim bladder that allows them to control buoyancy and maintain depth in the water column. When brought up from depth, the swim bladder can overexpand, causing barotrauma.
Barotrauma occurs when a rockfish is unable to release expanding gases in the swim bladder as it is reeled up to the surface. Barotrauma injuries can cause the eyes, stomach, or anus to appear to be inflated or greatly expanded. Although one might suspect that a rockfish with barotrauma is dead or fatally wounded - it’s not! Rockfish can be recompressed by returning the fish to the depth where it was caught. You can make the difference between life and death by helping rockfish get back to the bottom with a descending device.
The Benefits of Using Descending Devices
The most common reasons for discarding rockfish are catching a prohibited species, exceeding a bag or sub-bag limit or catching a small rockfish. The way you release your rockfish is very important as it provides an opportunity for that rockfish to survive, grow and spawn.
Figure 2. Mortality rates for yelloweye rockfish released at the surface and with a descending device at various depths. Click image to enlarge
Rockfish released at the surface that are caught deeper than 180 feet (30 fathoms) and released without a descending device are all counted as dead for management purposes as they have a high probability of succumbing to their injuries, predation from birds, sea lions or thermal shock from sun exposure. If you are not using a descending device to release rockfish and fishing deeper than 180 feet, the best angling practice is to retain all legal rockfish until you get your bag limit versus throwing back smaller rockfish.
Mortality is decreased when the rockfish is returned to appropriate depths as soon as possible, and the best way to minimize time on the surface is using a descending device. When descending devices are utilized, discard death rates are significantly reduced. This decrease in mortality is taken into account in catch estimates used for recreational fishing regulations and tracking catch against annual harvest limits. In a recent study on discard mortality rates and the use of descending devices on different rockfish species, dependent on the depth, mortality rates were reduced by as much as 62 percent when descending devices were used, as seen in Figure 2 and Table 1.
Table 1. Mortality rates for various rockfish species caught within California waters when being released at the surface vs. using a descending device (DD) at different depths (fathoms = ftm). Bolded and highlighted values show depths where using a descending device increases survivability. All rockfish mortality rates can be found in the Pacific Fishery Management Council November 2022 Groundfish Management Report (PDF).
| Species
|
Surface Release
0-10 ftm
|
Surface Release
11-20 ftm
|
Surface Release
21-30 ftm
|
Surface Release
>30 ftm
|
Using a DD
0-10 ftm
|
Using a DD
10-30 ftm
|
Using a DD
30-50 ftm
|
Using a DD
50-100 ftm
|
| Black
|
11%
|
20%
|
29%
|
63%
|
11%
|
16%
|
24%
|
63%
|
| Black-and-Yellow
|
13%
|
24%
|
37%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Blue
|
18%
|
30%
|
43%
|
100%
|
34%
|
34%
|
53%
|
92%
|
| Bocaccio
|
19%
|
32%
|
46%
|
100%
|
34%
|
34%
|
53%
|
92%
|
| Brown
|
12%
|
22%
|
33%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Calico
|
24%
|
43%
|
60%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Canary
|
21%
|
37%
|
53%
|
100%
|
3%
|
3%
|
18%
|
92%
|
| China
|
13%
|
24%
|
37%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Copper
|
19%
|
33%
|
48%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Gopher
|
19%
|
34%
|
49%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Grass
|
23%
|
45%
|
63%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Kelp
|
11%
|
19%
|
29%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Olive
|
34%
|
45%
|
57%
|
100%
|
34%
|
34%
|
53%
|
92%
|
| Quillback
|
21%
|
35%
|
52%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Tiger
|
20%
|
35%
|
51%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Treefish
|
14%
|
25%
|
39%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Vermilion
|
20%
|
34%
|
50%
|
100%
|
9%
|
9%
|
30%
|
38%
|
| Widow
|
21%
|
36%
|
52%
|
100%
|
34%
|
34%
|
53%
|
92%
|
| Yelloweye
|
22%
|
39%
|
56%
|
100%
|
9%
|
9%
|
11%
|
38%
|
The California Recreational Fishery Survey (CRFS) interviews anglers and collects data on the use of descending devices on rockfish released by recreational anglers and applies lower mortality rates to rockfish released with a descending device. By using descending devices and participating in CRFS surveys, you are providing information that improves our fisheries, resulting in potential for longer seasons or access to deeper depths.
Descending devices in action
Barotrauma Recompression Research
Canary Rockfish - Evidence of Recompression Success
China Rockfish - Evidence of Recompression Success
What Not To Do - The Dangers of "Venting"
Don't Vent, Descend! - Location of rockfish swim bladder and protruding stomach. Click image to enlarge
A dangerous, misinformed practice that is common in the fishing world is “venting”. Also known as “deflating” or “fizzing”, it refers to releasing excess gas within the swim bladder by inserting a hypodermic needle, knife, or other sharp object into the swim bladder. This is a dangerous practice that commonly leads to injury or even death of the rockfish. The best practice for releasing unwanted rockfish is to avoid touching any protruding organs and to use a descending device to quickly return the rockfish to depth.
Dangers of Venting
- Causes internal damage to the swim bladder and other organs
- Can lead to infection
- Reduces fish's ability to regulate gas volume leading to changes in behavior after release
- Can cause injury to fishermen
- Can kill fish
Incorporating Descending Device Use into Management
Mortality rate refers to the chance the rockfish will die when released. By releasing the fish with a descending device rather than at the surface, the mortality rate of released rockfish is greatly reduced. CDFW records the number of anglers who use descending devices during angler surveys. Upon completion of your fishing trip, you may be contacted by a CDFW California Recreational Fishery Survey (CRFS) sampler. By utilizing a descending device and participating in the CRFS survey, the lower mortality rate associated with releasing rockfish with a descending device is incorporated into catch estimates, creating the potential for longer seasons or access to deeper depths. Using a descending device benefits you, other anglers, fishing communities and West Coast rockfish populations.
CRFS collects information from anglers that is necessary to estimate California’s recreational finfish catch including groundfish species by monitoring over 1,100 miles of coast and interviewing anglers at over 400 sampling sites. Annually, CRFS conducts over 7,000 sampling assignments and contacts over 68,000 fishing parties. During the course of an established fishing season, CRFS catch estimates are used to track against annual harvest limits.
Figure 3 illustrates applying the mortality rates for yelloweye rockfish, assuming all fish are returned to 30-50 fathom depth with descending devices compared to release at the surface. Click image to enlarge
When a CRFS sampler conducts an interview with an angler, anglers are asked a series of questions that are important for calculating catch and effort by species. These questions include how many of each species of rockfish were released, the depth it was caught, and if a descending device was used in its release. This information is used to split the estimates of discarded rockfish into those released at the surface and those released with a descending device. This is important because a rockfish’s mortality is significantly different when released at the sea surface versus with a descending device.
Table 2 (below) expands upon Figure 3's illustrative example and shows the impact using a descending device to release prohibited species can have over the course of the fishing season.
If we assume that 10 metric tons of yelloweye rockfish are released during the season with descending devices, the mortality rates on those fish will result in an estimated 1.3 metric tons of yelloweye rockfish dying from barotrauma. Compare this to 6.7 metric tons dead if all the yelloweye rockfish were released at the surface: using descending devices results in an 80 percent reduction in overall mortality.
In this situation it means that if all 10 metric tons of yelloweye rockfish were released with a descending device, the total mortality impact would be 5.4 metric tons less during the season. This example shows the maximum impact that using a descending device could potentially have on the release mortality for this species of rockfish.
In totality across all rockfish species, this could potentially translate to more fishing opportunity as the lower total mortality could allow for longer seasons or more access to species than would otherwise be allowed.
Table 2. Applying the mortality rates for 10 metric tons of yelloweye rockfish, showing the difference in resulting metric tons of mortality when using a descending device at different depths.
| Depth (ftm)
|
Metric Tons Discarded Catch
|
Surface Release Mortality Rate
|
Surface Release Metric Tons of Mortality
|
Descending Device Mortality Rate
|
Descending Device Metric Tons of Mortality
|
| 0-10
|
1
|
22%
|
0.22
|
9%
|
0.09
|
| 11-20
|
2
|
39%
|
0.78
|
9%
|
0.18
|
| 21-30
|
3
|
56%
|
1.68
|
9%
|
0.27
|
| 31-50
|
3
|
100%
|
3.00
|
11%
|
0.33
|
| 51-100
|
1
|
100%
|
1.00
|
45%
|
0.45
|
| Total
|
10
|
N/A
|
6.68
|
N/A
|
1.32
|
By using a descending device and participating in CRFS surveys, anglers can improve released rockfish survivability and CDFW can better evaluate our fisheries. These two practices have the potential to increase fishing opportunity, rebuild overfished populations faster and make California nearshore rockfish fisheries sustainable for generations to come. Please read the Pacific Fishery Management Council November 2022 Groundfish Management Report (PDF) for more information on the science behind the development of descending device mortality rates.
Resources
Video
This presentation provides information regarding barotrauma injuries and suggestions for how to address rockfish experiencing barotrauma. Please share:
Bring That Rockfish Down!
A brochure with tips and techniques for successfully releasing rockfish suffering barotrauma injuries.
Fish Identification
Still have questions? More information on groundfish fisheries in California can be found on our groundfish page, which includes additional information and resources on recreational and commercial groundfish. If you have a more specific question, contact us at groundfish@wildlife.ca.gov.