Hatchery fish emerge

A quick trip to the hatchery this morning as Jimmy Woods the hatchery manager said there was a good hatch underway. The water temp was a steady 4 degrees C and although a few of the eggs had hatched over the last two weeks today was the first significant hatch.

Very few eggs had hatched in the first tank (can’t remember which stock it held) but Jimmy said the eggs had elongated and were miss-shaped, a sure sign that the hatch was imminent.

Well developed eyes in these eggs

Well developed eyes in these eggs

 

One of the first to hatch

One of the first to hatch. The yolk sac is large in comparison to the body at this early stage. The little black specs on the eggs are particles of sediment that came in with the wee rise in burn levels last night. Harmless to the eggs in that quantity.

The Sandbank hatchery uses hexhatch trays which revolve slowly with the water flow. Each tray can hold a lot of eggs, up to 100,000 in a commercial environment.

Well stocked hexhatch

Well stocked hexhatch

Once they hatch the little alevins fall through the egg tray into a lower compartment.

Alevins in lower compartment

Alevins in lower compartment. The hatch in this tank was well underway.

Alevins amongst eggs still to hatch

Alevins amongst eggs still to hatch

 

Once the hatch is complete Jimmy shifts the alevins into the incubators which are located adjacent to each tank. They remain in the incubator until the yolk sac is almost absorbed and they are ready to feed.

Tank and incubator set up

Tank and incubator set up

The incubator in an clever arrangement to simulate the conditons found in a natural redd in the gravel. The water flows in from the bottom, through a gauze and a layer of pea gravel. The incubator is then filled with plastic shapes to provide resting areas where the alevins can remain relatively immobile during the absorption of the yolk sac. Once the alevins have absorbed the yolk sac they self release into the tank at the optimum time for feeding. The credit for the incubator idea is I think due to Peter Gray, ex Keilder hatchery.

Incubator showing upwelling flow and pea gravel in base

Incubator showing upwelling flow and pea gravel in base

Plastic shopes used for substrate in the incuabtor. They provide a large surface area for shelter.

Plastic shapes used for substrate in the incubator. They provide a large surface area for shelter.

The Dulnain and Avon stock were stripped first and they were the first to hatch. It has been 125 days since the bulk of the Dulnain fish were stripped. Few of the Fiddich stock have hatched yet but they were stripped two weeks later. Jimmy records the water temperature daily but we also have a temperature logger in the intake which I’ll download later. I reckon it takes about 450 degree days for the eggs to hatch; 125 days at an average of 3.6 degrees C, that sounds about right. Almost the same again before they are ready for feeding.

There are about 230,000 eggs in the hatchery and the mortality rate to date has been less than 2%. The fish are destined for mitigation stocking in burns where there are man made barriers to fish passage.

Jimmy is a great observer of detail in the hatchery. He was pointing out the bubbles on the water surface of the tanks where a lot of fish had hatched. This was due he said to the empty egg shells breaking down. Interesting how the egg shells are stable whilst intact but break down so readily once they hatch. When he was showing me the incubators he pointed out the bits of detritus stirred up from the bottom. The alevins can be seen feeding on these particles just before they appear in the tanks. If you are going to have a hatchery you may as well have a good one!

 

 

 

There are 5 comments for this article
  1. GRAHAM SALISBURY (SRG) at 8:10 am

    Hello Brian, after reflection and inspired by our state of the art but sadly underused facility at Sandbank I would like to put the following questions to you, using your regularly referred too scientific pyramid of the Salmon’s life cycle. You inform us that we currently have a nice broad juvenile base? You also inform us that the system is at optimum carrying capacity up to and including the 0+ Parr stage as there is no spare capacity in the system to increase stocking? (except above spey dam). The science, informing the management that currently only some 20% output is required from Sandbank hatchery, Tulchan as a result is not needed for additional production, and I think you have concluded most of these on several posts and at the Aberlour meeting last Autumn?
    Now let’s wind the clock back to when you used to fish for trout with your farther with your dry fly (your recent post)and would almost raise a parr on every cast, this view is unanimously supported by rods and ghillies the length of the system? Today parr are notably diminished, again unanimously agreed by rods and ghillies the length of the system. I am not going to be speculative and suggest by what percentage or number but let’s settle for the fact significantly less for ease?
    My question and fundamental point is what scale was your pyramid in those days to support those huge very obvious numbers of additional parr toward the top end of your pyramid? The 11 million sqm of habitat is relatively unaltered? Water abstraction may be factor? Food supply may be factor? And you may be able to add a couple of additional influences. Here’s the crux I can’t see around the carrying capacity for parr back then has shifted/shrunk to suit your recent surveys indicting we are currently well stocked with no opportunity for SRG autumn parr programme to be expanded? There are some serious gaps in my understanding of these issues.
    GRAHAM SALISBURY (SRG)

    • Brian Shaw Author at 9:38 pm

      Hi Graham,
      I have never said the system was at optimum carrying capacity for fry (don’t like the term 0+ parr; in Scotland juvenile salmon in their first year are known as fry, 0+ parr is more suited to southern climes where one year old smolts are common), if that was the case all the results would be in the top categories in the SFCC classification. What I did say was that the 2012 monitoring results were encouraging, and that there were reasonably healthy populations of fry throughout the catchment. The results from the mainstem in 2012 were a considerable improvement on the dip recorded 4 or 5 years before. It woud be interesting to see if the observations from those on the riverbank mirror those findings this year. I also stated quite clearly that parr numbers across the catchment have declined and there is room for improvement.
      I don’t recall referring to dry fly fishing with my father? But I don’t doubt the observations of those who have fished and ghillied on the river for years, they do match the results of the mainstem surveys. I place a great deal of store in anecdotal reports from good observers, even this weekend one of the Tulchan ghillies was able to confirm my thoughts on the penetration of salmon into the Chabet Burn as he had been brought up on its banks. What I will say is that my own experience parr don’t often reveal themselves unless there is a big hatch of flies in the right conditons. I remember one warm summer evening on the Smithston beat on the River Doon when the pools were alive with parr. That evening showed what the pools held but on other days you may conclude the river held few. The above Tulchan ghillie also made the same point.
      Last year I met with SRG members where the merits of parr stocking in the Dulnain were extolled. Subsequent surveys found a good excellent population of fry and lessor numbers of parr, just what would be expected in that river. Stocking in that situation is more than a waste of time and would have been completely counter productive and an example of bad stocking practice. I could add a few more to your list of negative influences mentioned in your comment but I’d agree that there is a huge amount of good habitat and the food supply looks more than adequate in the mainstem. Understanding the factors limiting juvenile production in the river is my primary concern. The Fishery Board is now working in many different areas to identify and and improve degraded habitat. The Spey stocking policy is now tailored to a justifiable size and reallocation of resources into habitat surveys and improvements is a strategy that is finding much support.

      Brian

  2. Bryan Herbert at 2:56 pm

    Hi Brian

    It is good to see the hatchery stock hatching well but I was wondering given that there is so few fish accessing the river above the spey dam would the board ever consider use of Tulchan hatchery for the production of juvenile fish from the spring stock. Then take those from fed fry and transfer them to an area above spey dam and then bring them on to the smolt stage before release. If this was done over 3-4 years with say a starting point of 250000 eggs each year and allowing for a 20% loss before smolt release.Then if having a return of between 1-3% as adult fish there is the possibility of between 2000-6000 per each smolting class to return to above the spey dam to kick start the breading stock in that underutilised area of the river. Given that the fish pass on the spey dam is fit for purpose and that there is a new fish counter on it then you should easily be able to monitor the success of a smolt release program without catching fish or genetic studies. Before you or others throw in the genetic integrity of the stock above the dam I believe that what stock that is there is way below the self-sustaining level required for the levels to be maintained as they are so you would have nothing to lose.

    Just a thought
    Bryan

    • Brian Shaw Author at 8:04 pm

      Hi Bryan,

      In response to your comments: It is good to see the hatchery stock hatching well but I was wondering given that there is so few fish accessing the river above the spey dam would the board ever consider use of Tulchan hatchery for the production of juvenile fish from the spring stock. There is more than enough capacity at the Fishery Board hatchery at Sandbank to produce stocked fish currently required

      Then take those from fed fry and transfer them to an area above spey dam and then bring them on to the smolt stage before release. Are you saying that they should be grown on to smolt stage above Spey Dam? At ambient temperatures that would take two years, require some sort of hatchery and staffing. A major problem would be a shortage of suitable broodstock, there are very few in the entire upper Spey now, alternative donor tributaries would have to be tapped.

      If this was done over 3-4 years with say a starting point of 250000 eggs each year and allowing for a 20% loss before smolt release.Then if having a return of between 1-3% as adult fish there is the possibility of between 2000-6000 per each smolting class to return to above the spey dam to kick start the breeding stock in that underutilised area of the river. Your anticipated return rate is well above other reported return rates for stocked smolts, by about a factor of about 10. There would never ever have been a smolt run of that magnitude from above Spey Dam, 20-30,000 more like it with an adult run of below 1000 surviving to make it above the dam during peak runs.

      Given that the fish pass on the spey dam is fit for purpose and that there is a new fish counter on it then you should easily be able to monitor the success of a smolt release program without catching fish or genetic studies. Before you or others throw in the genetic integrity of the stock above the dam I believe that what stock that is there is way below the self-sustaining level required for the levels to be maintained as they are so you would have nothing to lose. What about the smolt screens on the offtake. No point releasing smolts if there are questions about whether the screens are fit for purpose. We should never be complacent about maintaining the genetic integrity of the stock. The stocks in the Spey, as in all large rivers, have evolved since the last ice age to suit their surroundings. Any stocking programme must have the provenance of the stock at its core. Fish returning from a stocking programme are liable to spawn in and outwith the stocked area potentially harming the remnant stock in the area. The 2009 and 2010 annual reports summarise the stocking carried out above Spey Dam and the 2010 report provides information on adult salmon captured at the dam or in the immediate vicinity. Genetic profiling proved that none of the 38 adult fish captured in 2010 at the Dam were of hatchery origin, despite extensive stocking in the area in previous years. This shows that the fish most likely to succeed in that area are those native to that part of the catchment. Through adaption they are programmed with the correct characteristics to survive, e.g. smolt run timings, onset of spawning, growth rates etc. The SFB strategy is to bring about improvements in the infrastructure at hydro scheme and to develop the remaining stock in the hope of a more sustainable recovery. I certainly wouldn’t rule out hatchery intervention, I have always said there is a good case for stocking above the dam, but only when the circumstances are right and then only if appropriate broodstock were available.

      Just a thought. I hope my comments in italics are readable.

      Best regards

      Brian

  3. Olivier Devictor at 2:49 pm

    Brian
    Thanks for the update. Very interesting.
    Olivier

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