Harbor seals and salmon impacts

Posted by: bushbear

Harbor seals and salmon impacts - 01/25/16 01:32 PM

A very interesting article and short video clip on the impact of harbor seals in the Strait of Georgia. Expand it to the whole of the Salish Sea and then add in the potential impacts on rock fish, steelhead, and herring and other forage fishes, too. This is a problem that won't be easily solved.

http://www.vancouversun.com/technology/s...__lsa=4d4c-1b99


Seals blamed for drop in juvenile salmon stocks in Strait of Georgia: study

The marine mammal’s population has grown as salmons’ have declined

By Larry Pynn, Vancouver Sun January 24, 2016
Posted by: FleaFlickr02

Re: Harbor seals and salmon impacts - 01/25/16 02:17 PM

I was surprised to learn seal poo from the area showed that salmon were only about 5% of a seal's diet. Would have figured it much higher than that. If a group of animals whose diet is comprised only 5% of salmon can actually account for 50% or more of juvenile salmon mortality in their range, it would seem to suggest there are a lot more seals than the ecosystem can feed.

It also stands to reason that the effect would be increased as you travel further south in the Sound, to where fish from the extreme South Sound hardly have a chance at making the ocean at all.

I'm never quick to blame predators for our mismanagement of the resource, but in this case, it does seem like a reduction in numbers is justifiable, if not necessary.
Posted by: Larry B

Re: Harbor seals and salmon impacts - 01/25/16 02:33 PM

I certainly urge earliest peer review and publication so that our scientists and fish managers will no longer be able to ignore what has been and remains one of the 800 pound gorillas in the room!

During the 8 August 2015 Commission meeting a preliminary presentation was made of results of a study on Salish Sea (Puget Sound) salmon and steelhead smolt marine survival: http://wdfw.wa.gov/commission/meetings/2015/08/aug0715_06_presentation.pdf.

This study clearly correlated increases in harbor seal populations to decreases in smolt survival but also cautioned that correlation is not proof of a cause and effect relationship. Well, the B.C. study seems to clearly establish that a cause and effect relationship exists - at least in the study area (and reasonably in the rest of the Salish Sea).





Posted by: RUNnGUN

Re: Harbor seals and salmon impacts - 01/29/16 07:18 AM

Time to manage a major predator on a managed resource. Not to do so equals a zero sum game for all recovery efforts. I guess another way is stop all hatchery production and wait for nature to balance itself out, ie. starve them out!
Posted by: FleaFlickr02

Re: Harbor seals and salmon impacts - 01/29/16 07:55 AM

The messed up thing is that salmon only represent 5% of their diet, so without the salmon to eat, they'd just be slightly slimmer. That they can count on salmon for only 5% of their diet and still have such a profound impact on salmon stocks paints the picture of just how far out of hand the situation is. It also makes me wonder what effects they are having on the species that make up the other 95%!
Posted by: Larry B

Re: Harbor seals and salmon impacts - 01/29/16 08:19 AM

The cumulative impact of predators (cormorants, terns, seals, sea lions, river otters and (gasp) harbor porpoise) is the 800 pound gorilla managers seem reluctant to acknowledge. Why? Simple, because doing anything about them is so difficult politically.

ESA listed rockfish remain a significant factor in our fisheries (the 120 foot rule) and threat of further marine protected areas and/or rockfish protected areas yet it is known that predators consume rockfish to include juveniles in their near shore habitat. Just how many? Hard to tell but total seal food demand in Puget Sound is between 25 and 30 million pounds annually. Even 1% of that poundage would be 250-300 thousand pounds then try to figure out how many are ESA species. Even a WAG puts it way above the few individuals NOAA/NMFS allows as sport impact.
Posted by: WDFW X 1 = 0

Re: Harbor seals and salmon impacts - 01/29/16 08:31 AM

But they're soooo cute.
Posted by: Carcassman

Re: Harbor seals and salmon impacts - 01/29/16 09:16 AM

There is another aspect of the predation issue that is just as not-talked about. Te predators have to eat those fish. They can't go to Total Paycheck and buy a farmed fish. Or tofu. While the overall impact or predation needs to be understood there is only one predator that can survive just fine without the fish. And he won't share.

To me, you begin with a vision of what the whole system looks like, what is present, and in what abundances. A PUBLIC discussion of how many whales, seals, dolphins, and whatever else. Build the pyramid and figure what to do then.

Don't push (society) for the MMPA and ESA without understanding the end result of implementation including land-use, fishing down the food chain, and the myriad of other impacts.
Posted by: Paul Smenis

Re: Harbor seals and salmon impacts - 01/29/16 10:20 AM

If there was the appropriate amount of forage fish for these "predators" to feed on this wouldn't be a topic of discussion.

Fix the real problems and you'll get real results.
Posted by: Bay wolf

Re: Harbor seals and salmon impacts - 01/29/16 10:43 AM

Let them prosper and multiply. After all the fish are gone, I'm counting on them as a good food source when the zombie apocalypse hits. Be nice if they were good and fat!
Posted by: Bobberdoggin

Re: Harbor seals and salmon impacts - 01/29/16 11:34 AM

That would be awesome if they opened a season for harbor seals. I would have a harpoon turret mounted on the front of my jet boat that same day!
Posted by: Todd

Re: Harbor seals and salmon impacts - 01/29/16 11:50 AM

Originally Posted By: WDFW X 1 = 0
But they're soooo cute.


This.

My fear is that we are so awesome at ecosystem management that we could kill every seal, sea lion, porpoise, cormorant, merganser, and kingfisher in the entire Puget Sound Region, there would be an immediate measureable increase in salmon populations, which we would then immediately as feasible harvest right down to where we are now.

Why? That's the pattern that man has shown it is best at, all over the world in every culture.

Fish on...

Todd
Posted by: RUNnGUN

Re: Harbor seals and salmon impacts - 01/29/16 05:18 PM

Originally Posted By: War-Paint
If there was the appropriate amount of forage fish for these "predators" to feed on this wouldn't be a topic of discussion.

Fix the real problems and you'll get real results.


Good point. An example of that is the Columbia smelt runs the last two years. For my boat, the good smelt returns equaled less attacked hooked Springers. Whitnessed groups of the seals floating by relaxing. I was told so full of smelt they didn't even want to swim.
Posted by: Larry B

Re: Harbor seals and salmon impacts - 01/29/16 07:58 PM

Lots of forage fish out there! Those increased populations of seals, sea lions, mergansers, cormorants, harbor porpoise, and river otters simply cannot exist primarily on salmon/steelhead smolt or rockfish. But when there is a rush of food such as outbound smolts or the other swing of the food availability pendulum pushes predators onto rockfish as a food source they have an immense adverse impact and particularly on those ESA listed species we are trying to recover.

Example: Remember the mackerel invasion of the PNW some years ago? The Canadians released Barkley Sound smolts directly into that curtain of death and they were decimated. South Sound releases face different predators but the smolt loss is huge.

My belief is that the aggregate impact of predators is a significant limiting factor in recovery of many of our ESA listed species.
Posted by: Salmo g.

Re: Harbor seals and salmon impacts - 01/30/16 10:26 AM

"My belief is that the aggregate impact of predators is a significant limiting factor in recovery of many of our ESA listed species."

Yep.
Posted by: Carcassman

Re: Harbor seals and salmon impacts - 01/31/16 08:34 PM

Just remember that man is one of those predators, too. Why is "our" predation sacred and untouchable while the animals that have to eat wild fish can be culled?
Posted by: Dan S.

Re: Harbor seals and salmon impacts - 01/31/16 08:58 PM

Because we have opposable thumbs?
Posted by: Carcassman

Re: Harbor seals and salmon impacts - 01/31/16 09:42 PM

Good a reason as any
Posted by: Dan S.

Re: Harbor seals and salmon impacts - 01/31/16 09:45 PM

Let them try to hold a beer. smile
Posted by: blackmouth

Re: Harbor seals and salmon impacts - 02/01/16 08:21 AM

Originally Posted By: Carcassman
Just remember that man is one of those predators, too. Why is "our" predation sacred and untouchable while the animals that have to eat wild fish can be culled?


Where do you get that crap? Are the pinnipeds going to be at NOF? Do they buy fishing licenses? Just where are their hatcheries?
Posted by: Carcassman

Re: Harbor seals and salmon impacts - 02/01/16 10:21 AM

They exist.
Posted by: FleaFlickr02

Re: Harbor seals and salmon impacts - 02/01/16 12:16 PM

Interesting thing about the ESA is that it seems to work very well to recover some species, while other species continue to trend (albeit at a slower pace) toward extinction. Seals and ESA-listed salmon demonstrate both extremes. Both share similar habitats (in the salt, anyway) and depend on similar food sources, so why has one been so much more successful at recovery? I'm sure the whole story's nowhere near this simple, but I think the fact that we don't have a commercial market for seals might be a good place to start looking for answers.

I guess I'm naive, but I can't help wondering if salmon would be in better shape if we quit killing over half of them every year in the ocean. Hey - not killing them sure worked for the seals....
Posted by: chukar14

Re: Harbor seals and salmon impacts - 02/01/16 04:10 PM

See alot of parallels to the spotted owl ESA listing, they finally concluded that habitat was not the limiting factor and the predation and competition from Barred Owls was, end resulting reducing the number of barred owls, increases the number of spotted.

http://news.nationalgeographic.com/news/...pecies-science/
Posted by: Carcassman

Re: Harbor seals and salmon impacts - 02/01/16 04:27 PM

The reason the Barred Owl invaded was because of changes in habitat. Once it got here, in the degraded and second-growth, it kept expanding and then hybridized the Spotteds.

Same as when you put rainbow on top of cutthroat, even in a rather pristine place like Yellowstone. The rainbow outcompeted and out-bred them.
Posted by: TastySalmon

Re: Harbor seals and salmon impacts - 02/02/16 08:39 PM

Originally Posted By: FleaFlickr02
Both share similar habitats (in the salt, anyway) and depend on similar food sources, so why has one been so much more successful at recovery?

I guess I'm naive, but I can't help wondering if salmon would be in better shape if we quit killing over half of them every year in the ocean. Hey - not killing them sure worked for the seals....


The difference is a very large number of species prey on salmon at their varying life stages and exactly zero species prey on seals. Some killer whales obviously eat seals, but the pods that do so are rarely, if ever, in Puget Sound or the southern Strait of Georgia that they have no measurable impact on the harbor seal population.

Seal population growth is regulated only by the abundance of their prey. This said, once people stopped smoking seals indiscriminately out of fear of federal court, there was nothing stopping seal population growth. After talking to old timer anglers, commercial fishermen and Indians, I came to realize just how many seals got shot on a regular basis decades ago. This simply doesn't happen anymore, at least not at a rate that impacts growth.

In regards to not killing 50% of fish before they can spawn: we no longer kill any more than a negligible number (and in some cases zero) of wild steelhead yet steelhead populations in Puget Sound are not experiencing growth or are still declining. If the abundance of spawners does not influence overall population size, then there are other factors limiting population abundance and this could be true for coho and chinook. This is similar to putting $4,500 into your savings account with a 0.05% interest rate and getting disappointed that it's not making you any money.

Every year more information comes out just how massive the impacts seals are having on salmon and steelhead. These impacts are not just on returning adults, but are also on juvenile chinook, coho and steelhead at astounding numbers.

I'd wager within 10 years, there will be public debates on the "ethical" number of seals to be culled.
Posted by: Larry B

Re: Harbor seals and salmon impacts - 02/02/16 10:38 PM

Hmmm, I seem to recall that they talked and talked before taking even minimal actions to respond to "Hershel" and his buddies only to find it was way too little and way, way too late for wild Lake WA steelhead.

History has a way of repeating itself.
Posted by: Carcassman

Re: Harbor seals and salmon impacts - 02/03/16 10:15 AM

As I recall, the LW steelhead rebounded after action was taken on the sealions and then went ito the tailspin from which it has not recovered.
Posted by: Larry B

Re: Harbor seals and salmon impacts - 02/03/16 02:05 PM

Originally Posted By: Carcassman
As I recall, the LW steelhead rebounded after action was taken on the sealions and then went ito the tailspin from which it has not recovered.


If that had happened I believe the managers would have run it up the public flagpole given the amount of negative press resulting from the "Herschel" debacle.

At the time I was living near the WDFW facility where "Herschel" was sent (sea lion purgatory?) and remember how he escaped into the neighborhood.
Posted by: TwoDogs

Re: Harbor seals and salmon impacts - 02/03/16 04:02 PM

Bigg's killer whales eat seals (and other mammals) and have been increasing quite a bit in the Salish Sea in recent years as the harbor seal population has increased. It would be interesting to see what data there are on what kind of impact they may be having on the seal population.