Fishing with Rod Discussion Forum

Please login or register.

Login with username, password and session length
Advanced search  

Author Topic: 2 Minute Survey for Orca Recovery  (Read 956 times)

IronNoggin

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 1149
  • Any River... Any Time....
2 Minute Survey for Orca Recovery
« on: November 28, 2017, 12:48:50 PM »

The Georgia Strait Alliance has put forth a survey to collect YOUR thoughts on potential steps being taken to try and recover the dwindling population of southern resident killer whales.

I would encourage all fishermen, and any with an interest to fill this out.
If we want to realize any fisheries down the road, letting them know your thoughts / position is important.

A few notes:

Recent studies and conclusions by biologists have determined that shutting down coastwide fisheries will have very little positive impact.
Those that should be considered for closures (their opinion again) focus on in-river netting, especially so on the Fraser.
Offshore fishing of mixed stocks apparently contributes but little to the overall problem.

Fish farms, although controversial, are most likely contributing to the problems.

At this point, sea lion and harbor seal populations are at an all time high, and recognized to be beyond carrying capacity.
Studies have shown that these two predators consume sixty-four (plus) percent of annual chinook and coho production in the Strait. A reduction in their numbers is likely the most beneficial undertaking we can engage in at this point.

Hatcheries, when run properly, can provide a good stop-gap to immediately address the shortfalls in chinook production.

Habitat enhancement is the second most efficient program we can in terms of increasing salmon production, and is the longest lasting.

The survey is located here: http://georgiastrait.org/2-minute-survey-for-orca-recovery-oat/

Cheers & Many Thanks for sharing your concerns!
Nog
Logged

Easywater

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 890
Re: 2 Minute Survey for Orca Recovery
« Reply #1 on: November 28, 2017, 03:33:41 PM »

I believe that this is a worth-while effort but I have a few questions.

In your notes, are those your comments or are they pulled from somewhere?
I would like to see more info on the levels caught through commercial fisheries and the percentage eaten by sea lions and seals.

My thoughts are:
- implement a salmon TAC the same way that halibut are managed.
- No in-river commercial netting.
Logged

IronNoggin

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 1149
  • Any River... Any Time....
Re: 2 Minute Survey for Orca Recovery
« Reply #2 on: November 28, 2017, 04:05:37 PM »

In your notes, are those your comments or are they pulled from somewhere?

My comments.

The current sports catch for chinook off WCVI vastly exceeds that of the commercial fleet (Area G Troll).
I know this for fact, I am one, and sit on the local SFAC as well. That is not in dispute.

As a consequence, while both sectors are scheduled for shut-downs, the hardest hit will be the recreational sector.

As I noted, the biologists (many of whom are buddies, as I am also a retired marine biologist) are noting these shut-downs will not result in significant reductions to the problem being faced. I tend to believe them.

I will dig up the study results that note the seal / sea lion depredation levels at 64 % per annum of the annual production of both springs and coho and post here.

Cheers,
Nog
Logged

RalphH

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 2089
Re: 2 Minute Survey for Orca Recovery
« Reply #3 on: November 28, 2017, 04:31:43 PM »


A few notes:

Recent studies and conclusions by biologists have determined that shutting down coastwide fisheries will have very little positive impact.
Those that should be considered for closures (their opinion again) focus on in-river netting, especially so on the Fraser.
Offshore fishing of mixed stocks apparently contributes but little to the overall problem.

Fish farms, although controversial, are most likely contributing to the problems.

At this point, sea lion and harbor seal populations are at an all time high, and recognized to be beyond carrying capacity.
Studies have shown that these two predators consume sixty-four (plus) percent of annual chinook and coho production in the Strait. A reduction in their numbers is likely the most beneficial undertaking we can engage in at this point.

Hatcheries, when run properly, can provide a good stop-gap to immediately address the shortfalls in chinook production.

Habitat enhancement is the second most efficient program we can in terms of increasing salmon production, and is the longest lasting.


Nog

Last published estimates on seal & sea lion predation is in the 35% to 60% range. That's a pretty broad. These estimates are derived from applying scat sampling at a few locations across the estimated 40,000 seals in the Straight of Georgia. Actual sample locations are mostly a few small areas associated with high hatchery production.

One thing is certain that simply pushing out more spring smolts through the hatchery without doing something to improve their survival rate isn't likely to help Southern resident Orcas much.

***************************

Though a few years old now, here's a good summary of some of the issues: https://www.eopugetsound.org/magazine/young-salmon


« Last Edit: November 28, 2017, 04:44:01 PM by RalphH »
Logged
"Never force conversation on a stranger. They are probably there just to fish and find solitude. If you ask a question or 2 and receive only answers...and no attempt to keep the conversation going, gracefully follow the implied suggestion and leave the angler alone"
               from " Courtesy and Safety"; Morris and Chan on Fly Fishing Lakes by Brian Chan and Skip Morris

IronNoggin

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 1149
  • Any River... Any Time....
Logged

RalphH

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 2089
Re: 2 Minute Survey for Orca Recovery
« Reply #5 on: November 28, 2017, 07:57:08 PM »

I don't believe that all the evidence is in. Two aspects  bother me. First most of the recent flurry of studies all involve more or less the same group of researchers. That alone makes me think the evidence needs further substantiation.  Science assumes results will be confirmed by other independent investigations, that the test and the results are repeatable. Second these papers constantly mix apples and oranges. Killer whale predation is described in terms of biomass. Pinniped predation is most in terms of individuals. I think this is misleading since whales mostly consume adult chinook while seals and sea lions mostly eat smolts - of which only about 2% will become reproducing adults.

Overall they find despite reductions in human harvest overall predation has increased which could mean humans haven't reduced their harvest enough. It' supposed to be in balance with the natural eco-system isn't it?

They also suggest or recognize that hatchery reproduction boost seal and sea lion predation on salmon smolts which could mean hatchery reproduction causes a significant % of the problem.

https://www.documentcloud.org/documents/4253872-ChascoEtal-OnlinePDF.html

Quote
Including uncertainty in four key parameters related to predator abundance, diets, and bioenergetics does not
qualitatively change the trends and relative impacts of the predators described above. Given uncertainty in these
parameters, the estimated total biomass of Chinook salmon consumed in 2015 was between 12,400 and 18,700
metric tons for 95% of the simulations. The total number consumed varied between 12.5 million and 59.8 million
individuals; this has higher relative uncertainty than biomass because it additionally incorporates uncertainty in
smolt size and smolt fraction parameters. In 2015, approximately half of the uncertainty in the estimated total
biomass of Chinook salmon consumed by marine predators can be attributed to killer whales (8,900 to 13,600
metric tons, Fig. 6a), while almost all of the uncertainty in the total number of Chinook salmon consumed can
be attributed to harbor seals (9.2 to 54.9 million individuals, Fig. 6b).

...we did not address structural uncertainty in the model formulation, for instance by applying a multi-model framework, this would be pos-
sible by comparing our bioenergetics approach to other methods such as individual-based models or time series modeling approaches. Best practices for applications of ecological models  suggest consideration of multiple models, addressing parameter uncertainty, and understanding that models such as ours are strategic tools to identify major tradeoffs and explore hypotheses.

...our analysis, approximately half of the Chinook salmon consumed by marine
mammals or available to fisheries are of hatchery origin. Hatchery releases are conducted to increase fishing opportunities and assist salmon recovery efforts by helping supplement wild populations of conservation concern. An unintended effect of these programs is that they may contribute to unforeseen interactions between wild and hatchery origin fish. Though our model did not include different predation rates depending on salmon origin (hatchery, wild), it is possible that hatchery origin salmon provide a subsidy for marine mammals, leading to a numerical response in these predators and ultimately an increase in predation rates on wild fish.

Logged
"Never force conversation on a stranger. They are probably there just to fish and find solitude. If you ask a question or 2 and receive only answers...and no attempt to keep the conversation going, gracefully follow the implied suggestion and leave the angler alone"
               from " Courtesy and Safety"; Morris and Chan on Fly Fishing Lakes by Brian Chan and Skip Morris

clarki

  • Old Timer
  • *****
  • Offline Offline
  • Posts: 1096
Re: 2 Minute Survey for Orca Recovery
« Reply #6 on: December 01, 2017, 10:52:53 AM »


Hatcheries, when run properly, can provide a good stop-gap to immediately address the shortfalls in chinook production.

Habitat enhancement is the second most efficient program we can in terms of increasing salmon production, and is the longest lasting.

Increasing hatchery production would take 4-5 years before we saw adult Chinook that the orcas could prey on.

Habitat enhancement would take longer.

Limiting Chinook fisheries would have an immediate impact, as early as 2018.

How about doing all three concurrently? 
Logged