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Size 17mm TL; 14mm BL. Rottnest Island, 20/4/17. Any help/suggestions greatly appreciated.
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This juvenile is confirmed as Microcanthus strigatus
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Surface wind stress on larval fish species.
Any publications or evidence would help.
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Rakesh Prasad Bhagat any follow-up evidence for your statement?
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I've come across this analytical issue a few times in the last couple of months. It's an Aquaculture oriented design and the question pertains to the most appropriate statistical analysis of what is a common issue. There are lots of complexities we could add, but I will make it a simple example.
Question: Is the performance of a larval fish affected by its rearing Temperature (High, Low) and Food (high, low)?
Method: Get parents to breed, pop fertilised eggs (1000) from a number of parents (mixed) randomly into 12 tanks, and then randomly assign the tanks to one of the 4 treatment combinations, with 3 tanks per Temp x Food combination.
Rear for 28 days, and then test the performance of the larvae - let's just say we test maximum swimming speed (our variable).
Analysis.
Now here's the issue.
The problem we have is an obvious non-independence among fish sampled from the same tanks (because they interact and produce social hierarchies). We can sample and assess swimming for multiple fish from the same tank, but all we are doing is getting a better idea of the position of the true mean of the overall population in the tank.
A typical GLM approach would be to simply nest the Tank effect, so we have two fixed effects (Temp, Food), their fixed interaction, and a Tank(Temp*Food) term. This would effectively use the means within the tanks as the replicates to test the main effects, thereby isolating the effects.
The alternative approach that I have seen recently is to use a linear mixed effects model, with Temp and Food as fixed effects, and Tank as a random effect.
To me this latter approach, while it may account for some uniqueness in the Tank, cannot account for the fact that the fish within the tank are interacting, influencing eachothers development and so do not represent independent estimates of what is going on. If you look at the df, it has a similar sensitivity to a GLM with no nested Tank term, which seems overly sensitive given the amount of real information. Maybe I'm just stuck in a GLM mindspace, but it strikes me as a design issue (i.e., telling the LME model that fish are reps when they actually aren't)..
I would appreciate someone much wiser statistically than me commenting on this train of thought.
Thanks
Mark
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There's a short paragraph on "controlling for non-independence in data-points" here: https://peerj.com/articles/4794/
The advantage of mixed effects models is not only that you can also account for non-independence among "slopes". As you said, you may assume more similarity from fish within tanks, but - e.g. - over time, fish within a tank may vary, too. In this case, or in general for longitudinal data, a random-slope-intercept-model is a good choice.
Furthermore, mixed models also have "shrinkage" on your estimate, reducing Type I/II error probabilities and giving more precise estimates.
Finally, if you have longitudinal data with time-varying predictors (fixed effects) that may correlate with your group (random) effects, this paper might be of interest for you: Bell, Andrew, Malcolm Fairbrother, and Kelvyn Jones. 2018. “Fixed and Random Effects Models: Making an Informed Choice.” Quality & Quantity. https://doi.org/10.1007/s11135-018-0802-x.
I tried to write down the formulas from the above paper in R, which you will find here:
Best
Daniel
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I am looking for the following paper in that symposium book.
POWLES, P.M., AND S.M. WARLEN. 1988. Estimation of hatch periods for yellow perch, based on otolith readings from juveniles (age-0). Am. Fish. Soc. Symp. 5: 60-67.
If you have that book and are willing to email me a copy of that paper, please let me know. Thanks.
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Awesome, thanks Andrew
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TL ~25mm. See at Rottnest Island on 28 April 2017 in a group of three conspecifics. Any thoughts greatly appreciated as it is out of range.
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This is probably Ostorhinchus fleurieu; O. aureus has the tail spot with concave margins, while they are convex in O. fleurieu.
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Small school of elongate larvae, TL ~20mm. Rottnest Island, Western Australia, March 2017. Possibly Clupeiforme (Engranulis australis, Spratelloides robustus or Hyperlophus vittatus)? Any help with identification or suggestions greatly appreciated.
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Julian and Lachlan - thank you very much for your input, regards Glen
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 I am attempting to key out hatchery reared larval fish ranging from 10 days old to 65 days old. I find Auer's larval key to be not as helpful as I would like.
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Gary; Here is a reference that should help you: Hasselman & Bradford. 2012. Discrimination of the endangered Atlantic whitefish (Coregonus huntsmani Scott 1987) larvae and juveniles. Canadian Technical Report Fisheries and Aquatic Science #2993. They distinguish Lake whitefish from ciscos, nice illuystrations. This is available online. Good luck.
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For the determination of uric acid content, I've read that there are colorimetric assays to measure uric acid levels of blood but how is it applicable as well to zebrafish embryo and larvae? Is there another method or procedure to measure uric acid levels in embryonic and larval zebrafish?
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Dear Kevser,
I refer you to the following References. hoping they will be useful information for you
1- Title : PATHWAYS FOR UREA PRODUCTION DURING EARLY LIFE OF AN AIRBREATHING TELEOST, THE AFRICAN CATFISH CLARIAS GARIEPINUSBURCHELL
By: BENDIK F. TERJESEN1 , TERRY D. CHADWICK, JOHAN A. J. VERRETH, IVAR RØNNESTAD1 AND PATRICIA A. WRIGHT
The Journal of Experimental Biology 204, 2155–2165 (2001) 2155 Printed in Great Britain © The Company of Biologists Limited 2001 JEB3312
2-
Chapter 44 - Osmoregulation and Excretion
Lecture Outline for Campbell/Reece Biology, 7th Edition, © Pearson Education, Inc.       
Regards
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Creek flows on average 80-150 cfs.  This is a small piece of a larger project, and I won't have time to check the nets at one hour intervals.  The creek substrate is mostly boulder and bedrock with deep pools, and I'm having difficulty finding the most suitable passive sampling gear to collect YOY.  Any advice is much appreciated!
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Thank you, Tim! This is exactly what I was looking for.  I'm going to look into the small fyke nets as well,
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We are trying to extract DNA from queen trigger fish larvae which are 0.5-0.6mm in size. We've tried  extraction by using commercial kits and PCI method but the quality and concetration of the DNA  were always low. Is there any method to use to extract DNA from tiny specimens?
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I wouldn´t pool larvae for DNA extraction. Is that this may result in overlapped haplotype sequences if these larvae belong to different haplotypes. You may try the cheapest, the salt-precepetation methods, using 100-200 microliters of the lysing buffer and calculating everything accordingly. You may take a look on my paper attached above for the protocols we use. All the best, Khaled
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pre-anal myomere count: 10
post-anal myomere count: 15
TL: 4.35mm
Specimen collected in Lower Green Bay 5/26/15
Habitat: vegetated, sandy substrate    Depth: 9.5 ft.
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Thanks for the new pictures, very helpful I think..
Sorry for the long response:
Percidae- The only one I thought possible was ruffe, but my European colleagues are much more familiar with this species and they are right that your larvae cannot be ruffe. So, Percidae is out.
Moronidae- The only moronid in range is white bass (M.chryops). Moronids hatch very small and by 4.3 mm should  not have a yolk sac. White bass YS larvae have the head over the yolk sac, not free as in your specimens. Other moronids are out of range and have very similar appearance to white bass. I suggest that your larvae are not Moronidae.
Centrarchidae- Lepomis would be the only genus that is reasonable, all other centrardhis in range have massive guts. I don't like Lepomis for your specimens because 1. There is no "Lepomis spot" on dorsum of gut. 2. At that size Lepomis have pectoral buds and I don't see that on your pictures. 3. Oil globules in Lepoms are rather small, the globule on your specimens is huge.
Sciaenidae- Freshwater drum (Aplodinotus grunniens). This species is recorded from Green Bay. If you compare your specimens to Auer, the size is correct for yolk sac larvae, the size and location of the oil globule works. Auer does not give myomere counts for yolk sac larvae but counts from her illustrations are close to yours. So, I vote for freshwater drum. If you have a large series of these larvae you could do the world a favor and publish a detailed description.
I work in the Hudson River and drum are becoming abundant. If anyone knows of a published description of the larvae other than Auer, please let me know!
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I am interesting in calculating RNA:DNA for larval and juvenile bluegill from a project I recently completed, but I'm having trouble finding methods for sonicating the fish. Does anyone have a protocol they would be willing to share? Or even some thoughts about the best way to go about it? 
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Hi,
I hope it's not too late.
I followed this protocol under a range of diferent conditions (sonicating vs no sonicating, among others) and published a couple of papers:
I think it's the best and most thorough protocol available and it gives a lot of details about the procedures.
For sonicating, rather than sonicate the sample for a couple of seconds and take it out to ice repeteadly, what I did was to put ice directly in the sonicator; that would allow me to sonicate the samples for up to 1 min, which could be enough depending on your samples.
Nevertheless, if you could use a shanking mill such as Retsch Type MM-2, sonication would not be necessary.
All the best,
David.
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I am interested in finding the most scientifically accepted approaches and equations for calculating ingestion rates for larval fish. Please also provide the references. Thanks, Konstantine
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What I am going to say is the most classical approach to quantify feeding on a resource by animals.
So, per capita ingestion rates should depend on two factors:
1. The species of larval fish, which determines, for instance, an intrinsic attack rate
2. The density of a resource, for instance, zooplancton, that larval fish feeds on.  Per capita ingestion rates should increase with resource availability.  However, it is reasonable to assume also that, when resource availability is very high, per capita ingestion rates should level off and reach some asymptotic value.
These two assumptions brings us to the famous Holling II type functional response. This is a two parametric function that has been fitted to data quite often since Holling paper:
C. S. Holling (1965). The Functional Response of Predators to Prey Density and its Role in Mimicry and Population Regulation. Memoirs of the Entomological Society of Canada, 97, pp 5-60. doi:10.4039/entm9745fv.
Since I am not an expert in larval fish feeding, my answer may sound very basic to you. However, let me say that whatever we try to do, it is very nice and fair to look always for connections to classical work. If this answer ends up not being very useful to you, it will be at least an acknowledgement to one of the classics in Ecology.
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I am trying to create a larval fish growth model for a class project and incorporate percent oxygen saturation into the metabolism component. I have found many references about oxygen uptake and metabolism, but I am having trouble finding a formula for the effect of oxygen concentration on oxygen uptake. It is only a class project, so I am not overly worried about accuracy of the formula, but a multi-species study from a respected researcher would be nice. It seems there should be a relatively simple relationship.
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Well, when you check the linked reference you will see that the oxygen partialpressure (PO2) at witch it should affects larval growth has actually a name. Mostly it's called critical oxygen partialpressure (Pcrit) and is the PO2 at which the aerobic metabolism is no longer possible. The difference between uptake and consumption is just the haemoglobine. So the curves look different. I guess fish have only an excess of oxygen when the PO2 in the water is pretty high.
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I am processing larval Fundulus heteroclitus for histopathological examination.  I will be making slides embedding and cutting whole fish ranging in size from 5 to 7.5 mm.  After slides have been made whole fish will be examined but the target tissue of examination will be the gills.  I am looking for suggestions on soak times and any other relevant tips on processing fish of this size.  
Thank you!
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You can use sagittal cryostate sections of 5 Um thickness. It is a very useful method for processing larvae.
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I am looking for a model describing how the predation pressure exerted by visual predators (i.e., mainly larval fish) on a small calanoid copepod changes throughout the year. 
The system is a boreal lake. The involved species are brook trout (Salvelinus fontinalis) young-of-the-year (YOY) as the supposed major predator and Leptodiaptomus minutus as the prey. Other potential predators include minnows (e.g., Couesius plumbeus, Notropis atherinoides), however, we believe they play a minor role as their habitat is limited to the littoral zone.
Knowledge about the larval biology of brook trout appears to be scarce and incomplete, and it is quite possible that it turns out that they are not important predators of this copepod. However, this would be very valuable information too. 
I am particularly interested in the seasonal change of the top-down control on the copepods, as I am trying to interpret results showing that these plankters undergo seasonal shifts in traits such as their individual dry weight.
Any suggestions of how to estimate the seasonal aspect of this factor, as well as useful information including larval development, typical seasonality of YOY biomass, YOY feeding preferences, relationship of feeding activity with environmental variables (e.g., water temperature) etc. will be highly appreciated! Big thanks to everyone who read until here ;-)
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Though I'm not aware of a model that investigated exacly what you ask, there are a couple of papers that specifically deal with predation of copepods.
Colleen Petrik did studies of prey selection and relation of larval fish and copepods:
Petrik, C.M., Kristiansen, T., Lough, R.G., Davis, C.S., 2009. Prey selection of
larval haddock and cod on copepods with species-specific behavior: a modelbased
analysis. Marine Ecology Progress Series, 396: 123-143.
Petrik, Davis and Ji, 2010. Coupling models of hydrodynamics, prey, and larval haddock on Georges Bank. ICES CM 2010:L18
For models temperature is suggested as indicator for seasonal predation varibility due to increased grazing rates. From copepod viewpoint:
Plourde, Maps and Joly, 2009. Mortality and survival in early stages control recruitment in Clanus finmarchicus, J Plankton Res 31, 4, 371-388.
which we used in a 3d model:
Ji, Stegert and Davis, 2013. J Plankton Res. 35, 1, 66ß79 (see downloads).
Hope this helps,
Christoph
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I am conducting a study using Artemia salina as a model organism for algal toxicity.  Previously I had only raised artemia to the point of hatching (24-48 hrs) and used them for feeding larval fish.  I now want to raise them to older ages, meta-nauplii stage (in which digestive track has formed) and adult.  To keep consistent with the conditions preferred by the algae I am studying, the artemia will be hatched and raised in 25 ppt artificial seawater in an incubator set to 25* C 12:12 light, dark cycle.  Any advice on distinguishing between the many molts phases this species progresses through before reaching adulthood would also be helpful.  
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But do you mean Artemia salina? American brine shrimp, A. franciscana, is the species used in most studies. A. salina is a species restricted to the Mediterranean region and Africa, and is actually threatened by the spread of A. franciscana through aquaculture. See e.g. the following papers
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We find that each pipette drop of brine shrimp in water deposits a highly variable amount. Does anyone use a tool or technique in their work that could potentially be co-opted to dispense a small predetermined number or weight of tiny brine shrimp?
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Hi, if you place the nauplii in a bucket with 10 liters (for example) of aerated saltwater (do not use air stone) then your counts may homogenize. (Take two aliquots of 0.5 ml each and then make a count, there should be no major difference to 10 nauplii between). The central idea is to keep the nauplii in a homogeneous suspension throughout the water column.
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We are trying out wild plankton feeding but a large proportion of the food items are thecate Ceratium spp. If these are not ingested by the fish, I would like to increase the copepod proportion.
I found articles suggesting that they do not. But is there any study suggesting that they could?
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No to my knowledge there is not, but I would be surprised if they were not feeding on them at all. Meeren & Næss 1993 found that tintinnids were part of the diet until age 20 days. However, these are likely more active that Ceratium which may make them more attractive or easier to spot.
Overton et al, 2010 and my self found cod larvae to ingest Gyrodinium spirale, Strombidium sp. and Oxyrrhis marina in high numbers when reared on them, but they seemed to prefer Acartia tonsa nauplii when these were also offered to the larvae. The results also suggested that the nutritional value of may not cover the added metabolic costs of the increased cod activity of ingesting these small prey in sufficient quantity. Therefore in my opinion they may only be considered a supplement and improvement of the very first feeding capabilities for the cod.
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In preparation for proteomic assessment.
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Embryo with yolk amounts to about ~100ug while without yolk to 5-10ug of protein.
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In studies on artificial breeding of fishes lack of age-size uniformity of spawners connected with small number of specimens in sample are the basic logical problem in conclusions, because fish fecundity is related with size-age. Similarly in larval rearing small number of specimens in sample did not reflect stock size structure, what means ignoring of hierarchy, behavior and weaning differences.
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If they are collecting wild fish during spawning, low number is understandable. Especially if fish they are working with has little or any commercial value, getting fish is at the mercy of whoever is running the nets etc. I work with wild-caught fish (walleye) and getting sexually mature fish with any kind of uniformity is very difficult. Also, the number of fish I get is at the mercy of the DNR people who run nets.