I think very limited culls are already the norm in most places w/o lots of urbanites. Ther'd be more if it wasn't for FB and YouTube. Not enough to really make any difference, tho. And it would need to be ongoing long-term on problem seals in chokepoints to make any difference, as well.
Here we go again, by Bob Hooton .
- Thread starter OldBlackDog
- Start date
We have less than 200 IFS this year. With more than a few being taken by the odd renegade FN with rod and reel as they hold over till the spring spawn in the Nicola, mouth of Nicola, Johns rock, red rock etc.
Let's say maybe 150 make it to spawn if they arent poached or die of natural causes or infections from bouncing off nets rocks etc.
How many smolts are we looking at that will reach the lower Fraser with these extinction level spawner abundance.
Also how many smolts are we looking at on an average year that pass through the lower Fraser of all salmon and steelhead combined?
Dave, AA or anyone could you please answer this.
Let's say maybe 150 make it to spawn if they arent poached or die of natural causes or infections from bouncing off nets rocks etc.
How many smolts are we looking at that will reach the lower Fraser with these extinction level spawner abundance.
Also how many smolts are we looking at on an average year that pass through the lower Fraser of all salmon and steelhead combined?
Dave, AA or anyone could you please answer this.
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I'll leave this for Dave or someone else w more steelhead experience. But.. how you would do that is apply estimates of sex ratios, average number of eggs per female (by age/size), hatching survival, and finally instream freshwater survival downstream to the mouth to that escapement estimate. The other question is much more work - adding up all the anadromous salmon returns by species/stock for the entire watershed by year and doing the same thing - but could be done.
DFO would have data on fry and smolt counts done annually ( at least they were) on the lower Fraser. Not sure if there would be any DNA data on these but should be.
Steelhead spawner success is probably unknown but would like to be shown wrong on this. matchbox notes ... 75 females x app 8k egg fecundity, divided by unknown mortality would equal a number of smolts. Figure maybe 1-2% survival, at best, for these.
Dave was correct in saying that the outmigration period last for weeks to months. However, adult return timing is quite a bit tighter (often with 1-3 weeks), and the water temperatures also play a role in incubation timing. So, the expected date of 50% hatch-out for each watershed is fairly tight going by ATUs, but different watersheds would have differing temperature regimes. But not all steelhead migrate out, and most smolts have to reach a certain critical size to want to outmigrate. Then there are life history traits that kick-in wrt what habitat types you find them in from freshwater all the way out to and including salt water.
So - long story short - DNA from smolt traps (if available) would really be critical in nailing down that outmigration period - as Dave pointed out.
So - long story short - DNA from smolt traps (if available) would really be critical in nailing down that outmigration period - as Dave pointed out.
wildmanyeah
Crew Member
Out of a return of a few hundred Returning. 50 steelhead were “ released” from gillnets
Sharphooks
Well-Known Member
Sounds like the most stunning oxymoron of the year: ....”50 steelhead were released from gillnets...”. If I’d been drinking coffee while reading that line, it would have come out of my nose and sprayed the screen of my laptop
I am at a loss for words trying to make sense of the concept that one or a group of pinnipeds could somehow be an existential threat to downstream migrating steelhead smolts. Sounds like a huge calorie burn for not too much. Not a good business model for pinniped survival.
And meanwhile, all the hackles go up when the most obvious mischief to downstream migrating steelhead smolts is mentioned; in-river gillnets extirpating what few remaining up-river POTENTIAL spawning IFS steelhead there are remaining in the systems.
Pinnipeds smolt predation? It’s like a Kabuki play. It’s outlandish! There’s a 600 pound pink elephant wrapped in a gillnet standing in the middle of the room but let’s flirt with the idea of a pinniped cull because a seal was seen chasing a smolt
There are agendas here. They crack in the breeze like a flag. I keep getting wiffs of mildew or something that’s just a bit off. I can’t put my finger on it but it’s very disconcerting.
I am at a loss for words trying to make sense of the concept that one or a group of pinnipeds could somehow be an existential threat to downstream migrating steelhead smolts. Sounds like a huge calorie burn for not too much. Not a good business model for pinniped survival.
And meanwhile, all the hackles go up when the most obvious mischief to downstream migrating steelhead smolts is mentioned; in-river gillnets extirpating what few remaining up-river POTENTIAL spawning IFS steelhead there are remaining in the systems.
Pinnipeds smolt predation? It’s like a Kabuki play. It’s outlandish! There’s a 600 pound pink elephant wrapped in a gillnet standing in the middle of the room but let’s flirt with the idea of a pinniped cull because a seal was seen chasing a smolt
There are agendas here. They crack in the breeze like a flag. I keep getting wiffs of mildew or something that’s just a bit off. I can’t put my finger on it but it’s very disconcerting.
searun
Well-Known Member
Nailed it.... science documenting the significant role of predation is clear. Wish-believing that removing gill nets will solve salmon decline problems while ignoring the cumulative impact of predation on both out-migrant smolts and adult in-migrants at predator pinch points where there are aggregations of prey is analogous to flat earth thinking. Seals are smart adaptive critters - they will move to times and places where they can take advantage of an abundant food source. We are witnessing sea lions following migrating Chinook all the way down the coast. Who hasn't seen that? Yes the role of NRKW in Chinook size at age is now well documented - see the NOAA research on that. https://www.pnas.org/content/116/52/26682Harbour seals are relatively weak swimmers as compared to sea lions (and not humans) was what observations I shared, Whitebuck. So, they change their behaviour to accommodate their needs. I would assume that they travel upstream in any canyon close either to the sides and/or the bottom where the current is less.
And Dave - thanks for the admission. I have seen seals go after small amounts of Eulachons. In one creek I saw 20-30 Harbour seals after 200-300 Eulachon. The Eulachon never stood a chance. Seals can work together to improve their own odds, if they want to - esp. if they are both hungry and determined - which they are.
And if they only manage to get ~50% of the less numerous Fraser chinook and interior steelhead smolts (remember they preferentially prey on the larger smolts) - wouldn't that be called depensatory mortality?
The dynamics of fish populations at low abundance and prospects for rebuilding and recovery
Abstract. Previous meta-analysis of spawner–recruit relationships suggested that depensatory behaviour is uncommon, and stocks pushed to low abundance areacademic.oup.com
The Variability among Populations of Coho Salmon in the Maximum Reproductive Rate and Depensation on JSTOR
Estimating parameters for population-dynamics models is a critical component in assessing extinction probabilities of populations. For many individual populatio...www.jstor.org
So predation is a much more significant issue than many of us had previously thought possible. Where and how we address it is the tricky bit.
To be clear, gill nets are a significant problem - but when you line up all the major known contributors to salmon and steelhead declines and apply a cost/benefit lens addressing gill nets is way down my list of things that pass the cost/benefit test. Even Rob Bison's analysis ranked addressing predation well ahead of fishery impacts in producing a recovery response. I think some folks are loosing sight of this because certain fishery savants have been preaching the evils of FN and Commercial netting.
Remember, those nets existed during the 1980's and some of the highest steelhead returns the province ever experienced - why was there no collapse of the fishery then? And think about the pinniped population recovery post the 1970's ban on hunting, and how that population recovery corresponds with the 1990s forward collapse of steelhead, and now stream-type chinook. Coincidentally both are larger smolt size - is that the common denominator? Does size make you more attractive as prey? There is some interesting research showing that even though there are roughly 10 times more ocean type chinook out-migrating smolts (smaller in size than coho smolts) on the Qualicum River hatchery than their larger but less abundant Coho cousins, it is the larger coho which make up the majority of seal diets. Size does matter in nature.
Food for thought.
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Searun, where are you getting your information re the size of upper Fraser chinook smolts? I have seen many and they are not particularly large ... remember, most of the 18 months or so they stay in freshwater is not optimum for growth.
searun
Well-Known Member
This DFO summary is a little dated, and does not include some of the more recent research - but its a good overall summary of what was becoming a broader understanding of the growing predation problem:
Simulation modelling indicates that mortality rates of Chinook Salmon from marine mammal predation increased in the 1990s relative to levels during the preceding 30 years (Figure 26). These results may be partially explained because predators were eating a higher proportion of fish due to declining Chinook Salmon populations (Bailey pers. comm. 2018), although other models suggest this interpretation may not be supported by the evidence (Preikshot et al. 2013). Nevertheless, populations of Sea Lions, Harbour Seals, White-sided Dolphins, and Humpback Whales dramatically increased since the 1970s and may have led to higher consumption (Riddell et al. 2013; Chasco et al. 2017). Between 1970 and 2015, for example, the annual biomass of Chinook Salmon consumed by pinnipeds in Puget Sound (Washington State, USA) rose from 68 to 625 tons (Chasco et al. 2017).
Northern and southern resident killer whales – which in 2013 totalled approximately 350 animals in BC waters – are considered salmonid specialists (Brown et al. 2013a). These whales congregate in groups during summer and fall in specific areas to intercept salmon migrating to natal spawning rivers. Extensive field studies of foraging behaviour indicate that resident killer whales forage selectively for Chinook Salmon and, to a lesser extent, Chum Salmon (Ford and Ellis 2006; Hanson et al. 2010). The whales appear to target large fish, with most being four years of age or older. Riddell et al. (2013) discuss workshop findings that identified the South Thompson Chinook Salmon population (DU12, DU13 and DU14) as the dominant stock in the diet of southern resident killer whales. Other Fraser River stocks of Chinook Salmon, some of which are declining, also figure prominently in the diet of resident killer whales. While only assessed during a single year and not considered in relation to relative DU abundance for that year, Hanson et al. (2010) ranked each DU in terms of inferred importance as follows: Upper Fraser (DU11), Middle Fraser (DU7, DU8, DU9, DU10), South Thompson River (DU12, DU13, DU14), and Lower Fraser stocks (DU2, DU3, DU4, DU5, DU6).
Harbour Seal abundance along the Pacific coast has increased dramatically since harvests ended in the late 1960s (Brown et al. 2013a). Consistent with trends south of the border, Harbour Seal abundance increased in the Strait of Georgia at a rate of 11.5 percent per year after the mid-1970s before stabilizing in the mid-1990s at about 40,000 animals. This trend is typical of the BC coast generally, with current total abundance estimated at 105,000 animals (Olesiuk 2010). Extensive scat collections during the 1980s indicated that Harbour Seals in the Strait of Georgia consumed a wide variety of prey species, but their diet was dominated by Herring and Hake. Overall, salmonids represented only about 4-7 percent of their diet, with salmonid consumption concentrated on pre-spawning adult salmon in estuaries and rivers (Olesiuk 1993; Thomas et al. 2016). Such predation can potentially be a major source of mortality for returning adult Chinook Salmon in cases where run size is small and habitat modification increases vulnerability to predation (for example, channelization of lower Puntledge River). Juvenile salmon, including Chinook Salmon, are also preyed upon by Harbour Seals (Thomas et al. 2016). Predation of juveniles can occur in marine areas as well as in rivers. Predation rates of downstream migrating juveniles can be significant in areas that are artificially illuminated at night such as bridge crossings (for example, Puntledge River, Olesiuk et al. 1996). The constrained morphology of a river can increase vulnerability to highly mobile and agile predators such as seals. The extent of predation on juvenile Chinook Salmon by Harbour Seals in natural settings is currently unknown. Chasco et al. (2017) estimate that between 1970 and 2015 the annual biomass of Chinook Salmon consumed by pinnipeds (Harbour Seals [Phoca vitulina], California Sea Lions [Zalophus Californianus], Steller Sea Lions [Eumetopias jubatus]) in Puget Sound increased from 68 to 625 metric tons. By 2015, pinnipeds consumed double that of resident killer whales and six times the combined commercial and recreational catches.
Steller Sea Lion abundance in British Columbia has increased approximately three-fold in BC since harvesting ended in the late 1960s (Brown et al. 2013a). Prior to 2013, abundance was increasing at 5 percent per annum and, based on pup production, current abundance in BC and adjacent waters of Southeast Alaska is approximately 60,000 animals, which is considerably greater than the estimated abundance for the early 1900s. Steller Sea Lions range widely in coastal waters, but during summer the majority congregate at traditional breeding rookeries, the largest of which are found in the Scott Islands, off the north end of Vancouver Island, and at Forrester Island, Alaska just north of the Haida Gwaii (Queen Charlotte Islands). Diet studies using prey remains found in scats collected at these rookeries and other haul-out sites indicate that Steller Sea Lions feed on a variety of fish and cephalopods, and that salmon constitutes a significant portion of their diet particularly in summer and fall. Salmonids have been estimated to represent about 10 percent of their overall diet (Olesiuk et al. 2010). On average, Steller Sea Lions eat about 18 kg of prey per capita per day, which may translate to about 17,200 tonnes per year for the population that uses Canadian waters. Preliminary studies on the salmonid species composition of Steller Sea Lion diets indica
Simulation modelling indicates that mortality rates of Chinook Salmon from marine mammal predation increased in the 1990s relative to levels during the preceding 30 years (Figure 26). These results may be partially explained because predators were eating a higher proportion of fish due to declining Chinook Salmon populations (Bailey pers. comm. 2018), although other models suggest this interpretation may not be supported by the evidence (Preikshot et al. 2013). Nevertheless, populations of Sea Lions, Harbour Seals, White-sided Dolphins, and Humpback Whales dramatically increased since the 1970s and may have led to higher consumption (Riddell et al. 2013; Chasco et al. 2017). Between 1970 and 2015, for example, the annual biomass of Chinook Salmon consumed by pinnipeds in Puget Sound (Washington State, USA) rose from 68 to 625 tons (Chasco et al. 2017).
Northern and southern resident killer whales – which in 2013 totalled approximately 350 animals in BC waters – are considered salmonid specialists (Brown et al. 2013a). These whales congregate in groups during summer and fall in specific areas to intercept salmon migrating to natal spawning rivers. Extensive field studies of foraging behaviour indicate that resident killer whales forage selectively for Chinook Salmon and, to a lesser extent, Chum Salmon (Ford and Ellis 2006; Hanson et al. 2010). The whales appear to target large fish, with most being four years of age or older. Riddell et al. (2013) discuss workshop findings that identified the South Thompson Chinook Salmon population (DU12, DU13 and DU14) as the dominant stock in the diet of southern resident killer whales. Other Fraser River stocks of Chinook Salmon, some of which are declining, also figure prominently in the diet of resident killer whales. While only assessed during a single year and not considered in relation to relative DU abundance for that year, Hanson et al. (2010) ranked each DU in terms of inferred importance as follows: Upper Fraser (DU11), Middle Fraser (DU7, DU8, DU9, DU10), South Thompson River (DU12, DU13, DU14), and Lower Fraser stocks (DU2, DU3, DU4, DU5, DU6).
Harbour Seal abundance along the Pacific coast has increased dramatically since harvests ended in the late 1960s (Brown et al. 2013a). Consistent with trends south of the border, Harbour Seal abundance increased in the Strait of Georgia at a rate of 11.5 percent per year after the mid-1970s before stabilizing in the mid-1990s at about 40,000 animals. This trend is typical of the BC coast generally, with current total abundance estimated at 105,000 animals (Olesiuk 2010). Extensive scat collections during the 1980s indicated that Harbour Seals in the Strait of Georgia consumed a wide variety of prey species, but their diet was dominated by Herring and Hake. Overall, salmonids represented only about 4-7 percent of their diet, with salmonid consumption concentrated on pre-spawning adult salmon in estuaries and rivers (Olesiuk 1993; Thomas et al. 2016). Such predation can potentially be a major source of mortality for returning adult Chinook Salmon in cases where run size is small and habitat modification increases vulnerability to predation (for example, channelization of lower Puntledge River). Juvenile salmon, including Chinook Salmon, are also preyed upon by Harbour Seals (Thomas et al. 2016). Predation of juveniles can occur in marine areas as well as in rivers. Predation rates of downstream migrating juveniles can be significant in areas that are artificially illuminated at night such as bridge crossings (for example, Puntledge River, Olesiuk et al. 1996). The constrained morphology of a river can increase vulnerability to highly mobile and agile predators such as seals. The extent of predation on juvenile Chinook Salmon by Harbour Seals in natural settings is currently unknown. Chasco et al. (2017) estimate that between 1970 and 2015 the annual biomass of Chinook Salmon consumed by pinnipeds (Harbour Seals [Phoca vitulina], California Sea Lions [Zalophus Californianus], Steller Sea Lions [Eumetopias jubatus]) in Puget Sound increased from 68 to 625 metric tons. By 2015, pinnipeds consumed double that of resident killer whales and six times the combined commercial and recreational catches.
Steller Sea Lion abundance in British Columbia has increased approximately three-fold in BC since harvesting ended in the late 1960s (Brown et al. 2013a). Prior to 2013, abundance was increasing at 5 percent per annum and, based on pup production, current abundance in BC and adjacent waters of Southeast Alaska is approximately 60,000 animals, which is considerably greater than the estimated abundance for the early 1900s. Steller Sea Lions range widely in coastal waters, but during summer the majority congregate at traditional breeding rookeries, the largest of which are found in the Scott Islands, off the north end of Vancouver Island, and at Forrester Island, Alaska just north of the Haida Gwaii (Queen Charlotte Islands). Diet studies using prey remains found in scats collected at these rookeries and other haul-out sites indicate that Steller Sea Lions feed on a variety of fish and cephalopods, and that salmon constitutes a significant portion of their diet particularly in summer and fall. Salmonids have been estimated to represent about 10 percent of their overall diet (Olesiuk et al. 2010). On average, Steller Sea Lions eat about 18 kg of prey per capita per day, which may translate to about 17,200 tonnes per year for the population that uses Canadian waters. Preliminary studies on the salmonid species composition of Steller Sea Lion diets indica
wildmanyeah
Crew Member
Marine mammals are a federally protected species. So to change this I gather our MPs in the house would have to draft legislation for a seal harvest.
As in they would have to stand up in parliament and say Ya or Na on the record?
As in they would have to stand up in parliament and say Ya or Na on the record?
OldBlackDog
Well-Known Member
And at the end of the day, this is how DFO will handle all west coast stocks. Quote:
That natural mortality includes everything from seal predation to temperature effects but more so than those factors, the plan highlights shortages of food that cod need, particularly capelin.
"High mortality rates may be related to cod dying of starvation."
While the full annual cod numbers assessment didn't go ahead in 2020 due to the pandemic, DFO science this past spring showed cod are resorting to cannibalism to survive, with a non-profit conservation group calling for the rebuilding plan to show leadership in the area.
Ever think that west coast stocks could have the same problem?
That natural mortality includes everything from seal predation to temperature effects but more so than those factors, the plan highlights shortages of food that cod need, particularly capelin.
"High mortality rates may be related to cod dying of starvation."
While the full annual cod numbers assessment didn't go ahead in 2020 due to the pandemic, DFO science this past spring showed cod are resorting to cannibalism to survive, with a non-profit conservation group calling for the rebuilding plan to show leadership in the area.
Ever think that west coast stocks could have the same problem?
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That's not how that works, WMY.
Any marine mammals on the SARA list (and not necessarily COSEWIC) are protected from a "directed" harvest. MPs have no say in COSEWIC or SARA unless we are talking about the one MP in cabinet who is also the Fisheries Minister who gets to decide what COSEWIC-designated animals end up on the SARA list. see: https://laws.justice.gc.ca/eng/acts/S-15.3/page-17.html#h-435647
So, Northern Fur Seals are listed as "special concern" under SARA. The rest of the seals are not listed, as far as I am aware - unless you have other information WMY?
Any marine mammals on the SARA list (and not necessarily COSEWIC) are protected from a "directed" harvest. MPs have no say in COSEWIC or SARA unless we are talking about the one MP in cabinet who is also the Fisheries Minister who gets to decide what COSEWIC-designated animals end up on the SARA list. see: https://laws.justice.gc.ca/eng/acts/S-15.3/page-17.html#h-435647
So, Northern Fur Seals are listed as "special concern" under SARA. The rest of the seals are not listed, as far as I am aware - unless you have other information WMY?
wildmanyeah
Crew Member
pretty sure legislation would need to be written for the west coast for a seal harvest or cull if it was any size, Maybe not for a government ran cull but wide scale harvest pretty sure.
Canada Gazette, Part 2, Volume 152, Number 14: Regulations Amending the Marine Mammal Regulations
July 11, 2018, Part 2, Volume 152, Number 14, Canada Gazette
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Here's s.6 from the Marine Mammal Regulations that you posted:
6 (1) An Indian or Inuk other than a beneficiary may, without a licence, fish for food, social or ceremonial purposes for
6 (1) An Indian or Inuk other than a beneficiary may, without a licence, fish for food, social or ceremonial purposes for
- (a) seals;
What really matters to the few steelhead left is another year has gone by with sweet FA being done. Meanwhile the few concerned people bicker about what the problem might be and what pray tell can be done about it. The vast vast vast majority of the people could give two hoots about a few fish swimming up the Fraser River.
I will make a bold prediction, at this time next year the few concerned people will still be bickering about what can and should be done for the handful of Thompson Steelhead that managed to make it past all the obstacles to spawn. Pretty soon one lonely doe will be scouring the Thompson watershed for a buck to spawn with and somebody will suggest we do a study to see what the problem might be.
I will make a bold prediction, at this time next year the few concerned people will still be bickering about what can and should be done for the handful of Thompson Steelhead that managed to make it past all the obstacles to spawn. Pretty soon one lonely doe will be scouring the Thompson watershed for a buck to spawn with and somebody will suggest we do a study to see what the problem might be.
searun
Well-Known Member
And that is precisely why we can ill afford to chase solutions that are less likely to deliver the recovery benefit that is most highly ranked. From a cost/benefit perspective based on what we know today, addressing predation will deliver the best outcome. From one fisheries savant to another, I predict you are correct about the in-fighting.
OldBlackDog
Well-Known Member
Dont worry, DFO will do exactly what it has done for the East Coast Cod.
They now state that they are starving to death.
They now state that they are starving to death.
At this point, anything being done would be a start.
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