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Return Update-July 8th - NSRAA chum returns last week (stat week 27) seemed to flatline. There was minimal cost recovery completed in Deep Inlet and a moderate amount in SE Cove. The Hidden Falls chum weekly return last week took a slight dip to 50,000 from the previous stat week 26 return of 62,000. So far this week there […]
Return Update-June 25th - NSRAA chinook returns have been picking up the past several weeks with a total estimated harvest in Stat Week 25 of 1,341 adults. The spring chinook fisheries in the Sitka area have harvested over 2,000 Medvejie chinook making up 47% of the Sitka Sound area commercial troll harvest. Currently the return is looking like it […]
Gulf of Alaska Chinook Salmon do not warrant listing under Endangered Species Act - NOAA has concluded its 12-month scientific review to not list Chinook salmon in the Gulf of Alaska as threatened or endangered under the Endangered Species Action (ESA). PRESS RELEASE NMFS ESA Ruling
NSRAA Salmon Bake & Hatchery Tour - NSRAA will be offering hatchery tours and a BBQ lunch at Medvejie Hatchery on Saturday, June 27th. Lunch will consist of barbecued King Salmon, baked potato, green salad, rolls, watermelon and non-alcoholic drinks. Tickets are $15.00 per person- CASH ONLY and can be purchased during office hours at NSRAA- 1308 Sawmill Creek Road. (8-5 Mon-Fri) […]
Support Alaska Hatcheries at Board of Fisheries - Alaska Board of Fisheries Proposals. Your voice is needed. The board of fisheries will take up three hatchery proposals at the statewide meeting. Proposals 170, 171, and 172 seek to impose broad, preemptive reductions or moratoria on Alaska’s private nonprofit (PNP) salmon hatchery program without demonstrating a causal link between hatchery production and the specific […]NSRAA Initiates Predator Study at Hidden Falls
Marine survival of chum salmon that return to Hidden Falls Hatchery have exhibited a declining trend since the early 1990’s and early predation by rockfish is hypothesized to be the primary cause. In spring 2021, NSRAA took first steps to address the decline by identifying the most prevalent rockfish species and their present and past consumption of hatchery fry relative to other prey at sites where hatchery fish are released. The most numerous rockfish were Black, Dusky, Quilback, and Silvergray rockfish in Kasnyku Bay where the largest chum releases occurred (see tables below) and these same species were most common at the release site near Whitewater Bay, except sculpin replaced Silvergray rockfish in being one of the highest numbered predators.
Catch rates using hook-and-line for the most common species did not significantly change before and during the time when 2g chum fry were released at both sites (see figures below). No change in catch rate was detected near Whitewater Bay when 4g chum fry were released at this site either. However, a significant increase in rockfish catch occurred at Kasnyku Bay during the 4g chum fry release in June. These results match observations that included no visual evidence of predation except when 4g chum fry were released at Kasnyku Bay when rockfish were observed feeding in large schools on chum fry at the water surface. Initial results of stomach contents obtained from captured predators the Alaska Department of Fish and Game permitted for sampling corroborate these findings, as chum fry were in around half the stomachs from rockfish captured on days surface feeding was observed.
Next steps are to conduct stable isotope analyses on tissues sampled from the permitted rockfish species. The turnover rate of stable isotopes in tissues of predators varies between species, fish age and size, and body part sampled, but is generally slow. Therefore, isotope analysis can be used to identify predator diets before capture for comparison to stomach contents at capture to determine if the hatchery releases cause predator shifts in diet. Isotope analysis can tell us this because hatchery fish are raised on fish food that has a unique carbon signature compared to prey in the marine environment, and the difference can be detected in the tissues (liver, muscle, fin, scales), and eye lenses sampled from the captured rockfish. The tissues inform the short term (days to months) prey items and the eye lenses can tell us how often hatchery fish were in the predator’s diet since the predator’s birth. This is possible because the eye lens grows from a core at birth by forming layers with time like an onion. The layers are delaminated and dried and isotope analysis performed as done with tissues to determine if hatchery fish were consumed. The fish whose eye lenses were extracted will also be aged by removing the otolith and counting annuli on it. The otolith nuclei indicates age zero when the lens core is created and the outer lens and annuli represent the fish diet and age at death, so the number of shifts in diet in the predators life can be determined from birth to time of capture.
The proportion of hatchery fish in the predator’s diet controls the carbon signature in the predator’s flesh. The stronger the hatchery carbon signature, the higher the consumption of hatchery fish. However, one factor is that upon release, hatchery fish no longer feed on hatchery food but capitalize on natural prey in marine waters and so gradually lose their unique carbon signature. Therefore, around 1,000 chum fry from each release group were held in an anchored net pen to feed on natural prey drifting into their enclosure. We culled 25 fish for isotope analysis the day before the fish were taken off their hatchery diet and an additional 25 per week were culled for two months to quantify rates the fish’s carbon signature becomes indistinguishable from non-hatchery prey. With this information and the isotope analyses from tissues and eye lenses, we can estimate durations and timings in the captured predators lives that hatchery fish were distinguishable and represented different proportions of their diet.
Results of the stable isotope analyses and study findings will be posted as they are developed.
Wed 9/1 Silver Bay Update
In cooperation with ADFG, NSRAA is opening a portion of the Silver Bay THA to common property seine on Thursday, Sept 1, to harvest fall chum salmon surplus to brood stock needs. This past Saturday a large buildup of Bear Cove bound chum staged in the Sawmill Cove area. NSRAA performed limited cost recovery in Sawmill Cove on Saturday Aug 28th to target a buildup of chum salmon staged near Sawmill Creek. The otolith data of this harvest of 190klbs indicated approximately 75% of those chum were Bear Cove bound fish, with the remainder Deep Inlet origin and overall 91% 3-year olds and 56% male. It appears the bulk of the volume was either harvested or left the Sawmill Cove area and has either moved on towards Bear Cove or backed out towards Deep Inlet. There continues to be some fish staged near Sawmill Creek and there will be no salmon stream restrictions for Sawmill Creek during the opening. This opening is to provide common property opportunity to harvest Bear Cove bound chum salmon surplus to brood stock needs. We will continue to monitor chum returns during the egg take at Medvejie and if brood stock numbers in Bear Cove continue to appear sufficient additional area and openings are likely to occur.
Tuesday 8/24 Update-Crawfish Inlet will open Thursday (8/26) for seine
The NSRAA Crawfish Inlet SHA will open Thursday (8/26) for seine. Openings in the Crawfish Inlet SHA for seine will mirror the Deep Inlet seine rotation with the exception of an hour later start time of 7am. ADFG has determined that it is warranted to open West Crawfish at this time as well and the West Crawfish area will be be open for seine the same days as the Crawfish Inlet SHA. Openings will continue through September 24th, 2021 or unless modified by subsequent ADFG Advisory Announcement. Cost recovery is still ongoing in both West Crawfish and Crawfish Inlet but it is anticipated to be completed on Wednesday (8/25). Most recent sex ratio sample available from Sunday 8/22 was 47% male in West Crawfish.
Sunday 8/22 Update
Cost recovery at Crawfish Inlet has gone very well the last few days and we are now at 60% complete. It is likely cost recovery will be complete Tuesday 8/24 and Crawfish Inlet will open to commercial seine Thur/Fri and mirror the Deep Inlet schedule the rest of the season. ADFG announcement will likely go out Tuesday afternoon. The last few days there has been a buildup in West Crawfish in Shamrock Bay and we have been performing cost recovery there as well. ADFG will look at buildup in West Crawfish next week and determine if a seine opening is warranted in West Crawfish as occurred last year.
Based upon observations at Bear Cove we now appear to have sufficient brood stock and will begin fall chum spawning next week. There continues to be large numbers of chum in Silver Bay from Entry Point to Bear Cove and troll harvest continues to be excellent from Silver Bay out past the Eckholms. It is almost certain that the NSRAA chum troll catch will break the 2013 record of 455k fish. Net fishing at Deep Inlet is going well but slower than would be anticipated by the adjacent troll harvest. The larger number of boats at Deep Inlet is also spreading out the catch reducing the per boat average. Based upon past fish behavior the chum will eventually stop biting for the trollers and push into Deep Inlet, question is when.
Friday 8/20 Update
What a difference a week makes. Chum returns to the Sitka area have improved greatly over the past week. We have seen our weekly catch numbers match our long-term average for Deep Inlet for stat week 33, and based upon current catch, this week at Deep Inlet may surpass the long-term average. Most recent Deep Inlet gillnet sample indicates 65% male and 63% 3-year olds. Troll catch continues to be excellent at both Deep Inlet and West Crawfish with a current catch rate of ~80k per week for the troll fleet at Deep Inlet/Eastern Channel alone. An additional 50k chum were caught last week in West Crawfish and similar numbers likely this week. Overall the fall chum troll catch has surpassed 300k fish and it is looking like it will top 400k before the troll catch drops off (455k highest DI NSRAA chum troll catch). On Thursday 8/20 there were an estimated 60-70 trollers working the drag from past the Eckholms to Entry Point in Eastern Channel and what appeared to be an excellent catch rate. With the good price this year for chum the troll commercial value is over $2m so far and currently leading the gear groups in total catch at Deep Inlet.
Crawfish Inlet cost recovery continues to go well. Today we are again fishing in the inlet with 2 boats and will continue Saturday with 4. Based upon observations we should be able to harvest over 1m pounds the next few days. If fishing continues to be this productive in Crawfish Inlet for cost recovery we will likely meet our goal early next week and potentially could have a common property seine opening on Thursday 8/26. Currently we are approximately 34% complete on cost recovery. Once Crawfish Inlet opens for seine we will mirror the Deep Inlet opening days/times at Crawfish Inlet to keep the fleet spread out.
After a dismal early summer chum return it is great to wrap up the year with a strong fall chum run.
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