Decompression devices for reducing barothrauma on Rockfish

[OldBlackDog]

Canadian Science Advisory Secretariat Pacific Region Science Response 2018/043
A REVIEW OF THE USE OF RECOMPRESSION DEVICES AS A TOOL FOR REDUCING THE EFFECTS OF BAROTRAUMA ON ROCKFISHES IN BRITISH COLUMBIA
Context
Pacific Rockfish (genus Sebastes) suffer high rates of barotrauma when they are brought to the ocean’s surface because they have a closed, or physoclistic, gas bladder. Although many jurisdictions recommend the use of descending devices that return recreationally caught fish with barotrauma to depth, little research on the use of these devices and the survival of recompressed fishes has been done in British Columbia.
Fisheries Management has requested advice from Science to inform decisions about management strategies for the recreational fishery that will achieve rockfish mortality reductions. It is expected that advice will be compliant with both the “DFO Sustainable Fisheries Framework” (SFF) policy and “A fishery decision-making framework incorporating the Precautionary Approach” (PA) policy.
Objectives
The Science Response will be used to provide advice with respect to the following objectives:
1. Review the state of knowledge regarding the effects of barotrauma on rockfishes and the ability of recompression devices to decrease mortality of released fish in the short- and long- term.
2. Document types of descending devices and what is known about each.
3. Synthesize study results for each species that occurs in BC.
4. Provide advice regarding research gaps and uncertainty.
This Science Response Report results from the Science Response Process of June 2018 on a review of the use of recompression devices as a tool for reducing the effects of barotrauma on rockfishes.

Conclusions
Rockfish species show resiliency in their ability to recover from barotrauma and to survive after recompression. However, the effects of barotrauma and the survival rates are complex in this diverse genus of fishes and a number of uncertainties remain. Although recompression increases the survival rates of discarded fish that would otherwise be unable to descend, and therefore remain at risk of predation by birds and mammals, accounting for uncertainties in short- and long-term mortality of descended rockfish complicates the calculation of mortality estimates. Given uncertainty about the long-term effects of barotrauma at the population level, maintaining effective rockfish conservation areas closed to fishing is a critical component to rockfish conservation and rebuilding plans. Incorporating the voluntary or mandatory use of descending devices in the management of recreational rockfish fisheries will require careful consideration because considerable uncertainty about their effectiveness to mitigate rockfish mortality remains.

Science Response: Rockfish Barotrauma and Recompression
This Report is Available from the
Centre for Science Advice Pacific Region Fisheries and Oceans Canada 3190 Hammond Bay Road Nanaimo, BC V9T 6N7
Telephone: (250) 756-7208
E-Mail: csap@dfo-mpo.gc.ca
Internet address: www.dfo-mpo.gc.ca/csas-sccs/
ISSN 1919-3769
© Her

 

[fish brain]

Science and DFO mentioned in the same paragraph?
Continuing studies about long term survival may be beneficial, but there is already enough science to prove that descending devices should be mandatory as mortality is 100 percent with out them.
DFO, Ugh

 

[Islander57]

It's just a no brainer, even without it being enforced, all anglers of rockfish should have a decompression device.

 

[agentaqua]

It's just a no brainer, even without it being enforced, all anglers of rockfish should have a decompression device.

x2 Islander - esp for those species "at risk", and preggie (gravid) females in the spring....

 

[agentaqua]

2018 Recreational Rockfish Management Measures

Outside Waters: Pacific Fishery Management Areas 1 to 11, 12-14, 20-1 to 20-4, 21 to 27, 101 to 111, 120 to 127 and 142

Season: April 1 – November 15

Rockfish, all species combined

• 3 Daily

• 1 of which may be a China, Tiger or Quillback Rockfish

• 0 of which may be Yelloweye Rockfish

• 0 of which may be Bocaccio Rockfish

• Possession limits are twice the Daily limit


Rationale

• The Inside and Outside Yelloweye Rockfish populations are currently at critical levels.

• The Outside Yelloweye Rockfish Rebuilding Plan strives to reduce fishing mortality to less than 100 tonnes by the 2018/19 fishing season. This applies to all known sources of mortality.

• Reductions to Yelloweye Rockfish mortality from recreational fishing are to be achieved by reducing targeted and incidental catch, both landed and released.


• Based on the recommendation of the Sport Fishing Advisory Board (SFAB), a new rockfish aggregate of China, Tiger and Quillback Rockfish was created. This new aggregate will help protect these inshore Rockfish species, as well as Yelloweye Rockfish.


Recommendations

• Avoidance: Do not target Yelloweye Rockfish. If Yelloweye Rockfish are encountered, move to another location.

• Identify 1: Know your rockfish species. Identification materials are available online (http://www.pac.dfo-mpo.gc.ca/fm-gp/commercial/ground-fond/rockfish-sebaste-eng.html). DFO will be distributing additional materials with rockfish identification tips in 2018.

• Identify 2: Know the location of Rockfish Conservation Areas (RCAs). Recreational Halibut and Salmon fishing are NOT permitted in RCAs (http://www.pac.dfo-mpo.gc.ca/fm-gp/maps-cartes/rca-acs/index-eng.html)

• Report: Note all releases in your fishing log.

• Release with a fish descending device: DFO supports the voluntary use of fish descending devices and will be working in 2018 with the objective of implementing mandatory possession of a fish descending device in 2019. Reducing time at surface and handling of the fish are key elements to successfully returning rockfish to depth.

• DFO will be consulting on additional management measures for both Inside and Outside Waters in 2018, for implementation in 2019.

 

[OldBlackDog]

Incorporating the voluntary or mandatory use of descending devices in the management of recreational rockfish fisheries will require careful consideration because considerable uncertainty about their effectiveness to mitigate rockfish mortality remains.

Science says!

2018 Recreational Rockfish Management Measures

Outside Waters: Pacific Fishery Management Areas 1 to 11, 12-14, 20-1 to 20-4, 21 to 27, 101 to 111, 120 to 127 and 142

Season: April 1 – November 15

Rockfish, all species combined

• 3 Daily

• 1 of which may be a China, Tiger or Quillback Rockfish

• 0 of which may be Yelloweye Rockfish

• 0 of which may be Bocaccio Rockfish

• Possession limits are twice the Daily limit


Rationale

• The Inside and Outside Yelloweye Rockfish populations are currently at critical levels.

• The Outside Yelloweye Rockfish Rebuilding Plan strives to reduce fishing mortality to less than 100 tonnes by the 2018/19 fishing season. This applies to all known sources of mortality.

• Reductions to Yelloweye Rockfish mortality from recreational fishing are to be achieved by reducing targeted and incidental catch, both landed and released.


• Based on the recommendation of the Sport Fishing Advisory Board (SFAB), a new rockfish aggregate of China, Tiger and Quillback Rockfish was created. This new aggregate will help protect these inshore Rockfish species, as well as Yelloweye Rockfish.


Recommendations

• Avoidance: Do not target Yelloweye Rockfish. If Yelloweye Rockfish are encountered, move to another location.

• Identify 1: Know your rockfish species. Identification materials are available online (http://www.pac.dfo-mpo.gc.ca/fm-gp/commercial/ground-fond/rockfish-sebaste-eng.html). DFO will be distributing additional materials with rockfish identification tips in 2018.

• Identify 2: Know the location of Rockfish Conservation Areas (RCAs). Recreational Halibut and Salmon fishing are NOT permitted in RCAs (http://www.pac.dfo-mpo.gc.ca/fm-gp/maps-cartes/rca-acs/index-eng.html)

• Report: Note all releases in your fishing log.

• Release with a fish descending device: DFO supports the voluntary use of fish descending devices and will be working in 2018 with the objective of implementing mandatory possession of a fish descending device in 2019. Reducing time at surface and handling of the fish are key elements to successfully returning rockfish to depth.

• DFO will be consulting on additional management measures for both Inside and Outside Waters in 2018, for implementation in 2019.

 

[searun]

Just read a CSAS science report that did point out that these devices are not completely fool-proof, however for certain species (such as Yellow Eye) caught and returned promptly and to the correct depth have survived quite nicely. The overwhelming evidence is that properly released fish using these devices have a significantly improved survival than currently practiced alternatives. Here's quick snippet of the CSAS conclusions, which support the current DFO policy approach to close recreational fisheries, but differ considerably to other scientific findings by researchers in the US, including NOAA. https://swfsc.noaa.gov/barotrauma/

..hmmm, can't help but wonder how objective CSAS has been in their review when it differs so markedly from the conclusions reached by other jurisdictions??

Conclusions

Rockfish species show resiliency in their ability to recover from barotrauma and to survive after recompression. However, the effects of barotrauma and the survival rates are complex in this diverse genus of fishes and a number of uncertainties remain. Although recompression increases the survival rates of discarded fish that would otherwise be unable to descend, and therefore remain at risk of predation by birds and mammals, accounting for uncertainties in short- and long-term mortality of descended rockfish complicates the calculation of mortality estimates. Given uncertainty about the long-term effects of barotrauma at the population level, maintaining effective rockfish conservation areas closed to fishing is a critical component to rockfish conservation and rebuilding plans. Incorporating the voluntary or mandatory use of descending devices in the management of recreational rockfish fisheries will require careful consideration because considerable uncertainty about their effectiveness to mitigate rockfish mortality remains.

 

[agentaqua]

Ya - they'll close large areas to rec & comm fishing w/o much data about whether or not it will be effective - but all of a sudden - descenders require "careful consideration because considerable uncertainty about their effectiveness". hmmmm...

 

[OldBlackDog]

It’s all about politics.
Wait till they advise where the new MPA areas are and what will or will not be allowed in them.

 

[wildmanyeah]

I think the department was basically saying Using descending devices does not warrant the removal of RCA's.

There was also previously a few different types of anglers

1. the guys that would target lings all days and not give a damn about creating a stawberry patch or...
2. The guys that would target lings but quit after they got a quta of rockfish

Now with descender is it free pass to play catch and release all day with rockfish? Do you keep the first rockfish you catch or do you play catch and release to try to get a bigger rock fish?

1. Angler 1 will save more rock fish with use of descender but...
2. Angler 2 might actually kill more

I agree with the comments made tho here descender are awesome!

 

[fish brain]

Let's look at this a different way.
1) No one seems to calling for the removal of RCA's because of descending devices, it is only DFO who seems to worried about this.
2) If descending devices are mandatory, the strawberry patch people would be required to potentially save some of the fish they might have killed, even if survival is not 100%
3) Ethical fishers will always be ethical. So fish caught while say trolling for salmon will be released using the descender, and if they are catching a lot of rock fish as by catch are likely to quit after a couple of rock fish anyway.

 

[wildmanyeah]

Lots of people want some rcas removed some are in great halibut locations or long cod locations. Some RCA are some good places that hold salmon too.

So why their may not be this great public out cry to have them all removed their is defiantly some that sports fishermen have asked DFO to have back.

 

[searun]

Don't expect to see any of the RCA's removed. Lots of people can want it, but not going to happen. No one at SFAB has asked for that to happen, and frankly there would be a battle to get any support for removing existing RCA's.

 

[agentaqua]

I guess my battle would be that RCAs are only somewhat effective for some areas for numerous reasons - but there are other options besides increasing RCAs - and jeepers - aren't descenders a damn good idea irrespective of any other issues? Anyone else with me on this point????

 

[searun]

Totally with you on that point. Anyone who argues against their use and effectiveness (ooops, DFO's CSAS team) is apparently wondering around with blinders. I would also say that new RCA's would similarly be met with a large degree of questions with respect to their effectiveness in light of other tools (such as descenders).

 

[fish brain]

I guess my battle would be that RCAs are only somewhat effective for some areas for numerous reasons - but there are other options besides increasing RCAs - and jeepers - aren't descenders a damn good idea irrespective of any other issues? Anyone else with me on this point????

I'm in, descenders on every boat as a condition of license.

 

[agentaqua]

Here's the latest from DFO:

 

[searun]

Read it, something doesn't add up when I compared the analysis with what NOAA has done.

 

[agentaqua]

Read it, something doesn't add up when I compared the analysis with what NOAA has done.

Which parts, searun?