14 replies to this topic

[nsakich]

Hi there,

 

I have a question for those of you that are familiar with pumpkinseed sunfish (Lepomis gibbosus) fry/larvae: do you think newly-hatched larvae would be able to swim through the holes in standard fibreglass window screen (i.e. with a hole size of about 1 mm x 1.2 mm)? I'm currently helping in the construction of containers that will be used to rear pumpkinseed fry for the first 6 weeks or so of their lives. These containers will be submerged in a lake, and it's important that fry are not able to escape and especially important that they don't swim from one container to another. The mesh "windows" won't extend all the way down to the bottom of the container, so if they never leave the bottom until swim-up and they can't fit through the holes after swim-up that might work too.

 

 

Thanks in advance,

 

Nick

[centrarchid]

I have raised the evil little buggers and many of their close kin like you are setting up for.  I strongly suggest use of Nitex Screen and select one of the coarser sizes just below what a typical window screen has.  I suspect the fiberglass may ding fish up while Nitex does not appear to do so.

 

 

Show a picture of apparatus especially the bottom part.  Prolarvae may be able to cross over in setup as I understand it.

 

How big are containers and will they be suspended in water column?

[nsakich]

I have raised the evil little buggers and many of their close kin like you are setting up for.  I strongly suggest use of Nitex Screen and select one of the coarser sizes just below what a typical window screen has.  I suspect the fiberglass may ding fish up while Nitex does not appear to do so.

 

 

Show a picture of apparatus especially the bottom part.  Prolarvae may be able to cross over in setup as I understand it.

 

How big are containers and will they be suspended in water column?

 

OK, thanks for your input. We've since decided to go with a different plastic screen with a slightly smaller hole diameter. The containers are 5-gallon buckets with large windows made of mesh. They will be anchored to the substrate with bricks. Algae-covered rocks will be placed in the bottom to help provide a first source of food. The fish will also be fed with plankton that we catch in a tow net (through a hole with a removable stopper that can be replaced afterwards to prevent the fry escaping). There will also be stronger mesh on the outside of the windows in the bucket to keep out predators and large, heavy debris. We'll be scrubbing the mesh periodically to keep the windows from getting clogged. We're just about to start construction on these buckets, so I can't post a picture just yet, sorry.

[centrarchid]

How many larvae will be stocked per bucket?  A problem I have encountered in low production areas is that plankton drifting through mesh will be too low to support good growth.  The larvae normally move about extensively in large schools even when forage density high which is denied when confined to bucket. 

[nsakich]

How many larvae will be stocked per bucket?  A problem I have encountered in low production areas is that plankton drifting through mesh will be too low to support good growth.  The larvae normally move about extensively in large schools even when forage density high which is denied when confined to bucket. 

 

One brood per bucket. And that's exactly the problem, hence the reason that we'll be feeding them plankton by hand that we catch on our tows.

[centrarchid]

Will not work.  You must reduce stocking density to a much lower number.  Depending on zooplankton density and size at location of buckets you might be able to raise anywhere from 0 to maybe 50 fry per bucket.  What you will see if forage is inadequate is a large variation in size even when survival good.  Large size variation is not typical within a brood through the early fry stage when conditions good.

 

 

We routinely rear sunfish larvae in a range of tank sizes, I have even done a few thousand Pumpkinseeds although could not do so with a full brood in a 5-gallon bucket as they consume too much food and will chew up oxygen too fast relative to the exchange with volume outside bucket.  The Pumpkinseed broods will be at least 1,500 fish and could exceed 5,000 which is going to give you real fun caused by variations in stocking density alone.  Have you considered pulling prolarvae from broods and stocking them into buckets at known density?

 

 

What is actual objective of this?

[gzeiger]

Nsakich, I don't recognize you and assume you are new here, so I will just say this - Centrarchid knows more about this topic than you or I imagine that there is to know and he hasn't shared a tenth of his experience so far in this thread.
 

I don't personally have any experience with it, so I will leave the actual topic alone. Just know that the advice you've received so far is good.

[centrarchid]

Hi there,

 

I have a question for those of you that are familiar with pumpkinseed sunfish (Lepomis gibbosus) fry/larvae: do you think newly-hatched larvae would be able to swim through the holes in standard fibreglass window screen (i.e. with a hole size of about 1 mm x 1.2 mm)? I'm currently helping in the construction of containers that will be used to rear pumpkinseed fry for the first 6 weeks or so of their lives. These containers will be submerged in a lake, and it's important that fry are not able to escape and especially important that they don't swim from one container to another. The mesh "windows" won't extend all the way down to the bottom of the container, so if they never leave the bottom until swim-up and they can't fit through the holes after swim-up that might work too.

 

 

Thanks in advance,

 

Nick

Nsakich,

 

As you plan your way through this be sure to discriminate between prolarvae and larvae.  Prolarvae are the life-stage for the first 5 days or more post hatch.  Early prolarvae are easier to handle and enumerate without harm.

 

If you are pressed into doing larvae, then handle them without actually touching them.  We move larvae by dipping them up using the little cups you pee into at Doctors office.  What I like to is have a few hundred of the cups where each is loaded with a larvae and water then placed on a table.  Then you gently dump captured larvae into culture unit with extreme love.  In our culture setting I like larvae to have full bellies when handled which seems to promote survival.

[nsakich]

Will not work.  You must reduce stocking density to a much lower number.  Depending on zooplankton density and size at location of buckets you might be able to raise anywhere from 0 to maybe 50 fry per bucket.  What you will see if forage is inadequate is a large variation in size even when survival good.  Large size variation is not typical within a brood through the early fry stage when conditions good.

 

 

We routinely rear sunfish larvae in a range of tank sizes, I have even done a few thousand Pumpkinseeds although could not do so with a full brood in a 5-gallon bucket as they consume too much food and will chew up oxygen too fast relative to the exchange with volume outside bucket.  The Pumpkinseed broods will be at least 1,500 fish and could exceed 5,000 which is going to give you real fun caused by variations in stocking density alone.  Have you considered pulling prolarvae from broods and stocking them into buckets at known density?

 

 

What is actual objective of this?

 

Thank you for your input. It is a phenotypic plasticity study wherein we will impose different environments on the fish once we get them back to the lab.

[nsakich]

Nsakich,

 

As you plan your way through this be sure to discriminate between prolarvae and larvae.  Prolarvae are the life-stage for the first 5 days or more post hatch.  Early prolarvae are easier to handle and enumerate without harm.

 

If you are pressed into doing larvae, then handle them without actually touching them.  We move larvae by dipping them up using the little cups you pee into at Doctors office.  What I like to is have a few hundred of the cups where each is loaded with a larvae and water then placed on a table.  Then you gently dump captured larvae into culture unit with extreme love.  In our culture setting I like larvae to have full bellies when handled which seems to promote survival.

 

I misspoke. We will be catching prolarvae. Again, thank you for your input.

[centrarchid]

Are you producing the broods under controlled conditions?  Harvesting prolarvae / embryos from wild nests?  Enumeration gets to be real fun when numbers to be high (SARCASM).

 

Will the pressure be applied while only in the lab?  Will pressure be forage type / nutritional or something abiotic?

 

Why are you wanting to rear fish in buckets?  To provide natural forage?

 

Is there a reason why you are not considering the culturing of the broods indoors?  Pumpkinseeds are among the easiest to rear in confinement.

 

Are you looking for morphological or behavioral changes with phenotype?

[nsakich]

Are you producing the broods under controlled conditions?  Harvesting prolarvae / embryos from wild nests?  Enumeration gets to be real fun when numbers to be high (SARCASM).

 

Will the pressure be applied while only in the lab?  Will pressure be forage type / nutritional or something abiotic?

 

Why are you wanting to rear fish in buckets?  To provide natural forage?

 

Is there a reason why you are not considering the culturing of the broods indoors?  Pumpkinseeds are among the easiest to rear in confinement.

 

Are you looking for morphological or behavioral changes with phenotype?

 

We're harvesting from wild nests and applying the pressure only in the lab. Pressure will be abiotic. Looking for both morphological and behavioural changes. I'd have to talk to the PI to get the answers to the other questions. I didn't design this study.

[centrarchid]

What age / size will fish be when trialed?

[nsakich]

What age / size will fish be when trialed?

 

I'm not sure. I think it'll vary depending on trial. Again, I'd have to ask the PI.

[centrarchid]

Talk to your adviser often.