Descending devices keep fisheries robust

Yelloweye Rockfish - Descending story
It’s good resource stewardship, when releasing bottomfish and halibut, to descend them to a deeper depth so they can survive.

Now, it’s also a requirement meant to keep the fishery robust.

A new Oregon Administrative Rule began on Jan. 1 for bottomfish and will start for halibut on May 1, when the season opens. It requires that recreational anglers have a descending device on board for ocean fishing, and that they use it.

“If you’re not going to keep the fish, getting it back down to depth it’s got a much higher chance of survival than it does on the surface,” said Lynn Mattes, who is the project leader for recreational ground fish and halibut for the Oregon Department of Fish and Wildlife’s Marine Resources Program.

Long way down
Rock fish have a swim bladder that inflates when the fish is brought to the surface. They’re not able to balance the gases in their system quickly enough, Mattes said.

When bloated, the fish have a hard time returning to proper depth.

Reasons to release a fish can vary. If the species is a yelloweye rockfish, for example, keeping them is prohibited in Oregon.

The benchmark for lowering the fish is 100 feet, Mattes said. Research indicates the fish can get back to proper depth on their own after that.

“We recommend people handle the fish as little as possible, and try to just handle them by the lower jaw and get it back into the water as quickly as you can,” Mattes said.

Preserve the species
The primary ports for bottomfish fishing are in Newport and Brookings, Mattes said. Halibut season is typically from early May through September. Rockfish have a 12-month season, with depth restrictions from April through September.

It’s important to keep bottomfish from becoming depleted, said Edmund Keene, board member for the nonprofit organization Oregon Coalition for Educating ANglers (OCEAN).

They can be very long-lived, with lifespans of 80 to 100 or more years, Keene said. Some don’t breed until they’re 15 years old or older.

“When those stocks of fish are depleted, their recovery time is very long,” Keene said.

Many choices
Descending devices can vary. One of the popular devices because it’s small and inexpensive is called a Shelton descender, Mattes said.

It looks like an inverted hook, but without a barb. You put it on an extra fishing line, insert it through the corner of the lower lip, put the fish and weight on the water’s surface, and then let it go. When the fish reaches a depth of 100 feet, you give a sharp tug on the line.

“That hook just slips out,” Mattes said.

Another device is called a SeaQualizer. Clamp it onto a fish’s lower lip, and set the device to release at 50, 100 or 150 feet.

“When that device gets to that water pressure, it releases and the fish can swim off,” Mattes said.

The amount of weight used on descending devices depends on the size of the fish. With a big 6- to 7-pound yelloweye rockfish, you may need 2 to 3 pounds of weight. A smaller fish may only require 24 to 32 ounces of weight to help return it to depth.

The devices are designed to easily be clipped on or tied onto a hand line or a broken extra fishing pole, Mattes said.

The state receives a mortality credit in the accounting of fish that it does for the federal government when descending devices are used, Mattes added.

“For the benefit of the fish now and our fisheries, hopefully using the devices reduces our mortality enough that we don’t have to take action to further restrict fisheries,” Mattes said, “as well as it helps the individual fish go back and breed, which will help our fisheries in the future.”

Additional resources
Learn more about fish recompression and how to use a descending device to safely return bottomfish to depth by visiting these ODFW links:
www.dfw.state.or.us/MRP/recompression/index.asp
http://www.dfw.state.or.us/MRP/recompression/send_that_rockfish_down.asp

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