Have you tried emailing a) Monterey Bay aquarium or B) Aquarium of the Pacific? They have large collections of bamboo shark eggs and seem to do a fair job at keeping them alive.

Hi Hans,

I have had a fair amount of experience incubating and rearing juvenile small spotted catsharks (Scyliorhinus canicula). Given that these species share some similarities in early life-history traits maybe I can offer a little advice.

Depending on the numbers you are rearing you should perhaps expect some natural mortality however, the fact that they are dying so quickly seems unusual, especially as you would expect natural mortality to occur before six months. Bacterial infection might be enough to cause the weaker individuals to die but maybe also this mortality could be down to either stocking density or the mixture of adults and juveniles. If the numbers are too high you might expect some individuals to be out competed at feeding time (but then the deceased are more likely to be very skinny). Alternatively, there could be fairly high harassment of these juveniles by the adults and stress could be killing them. I would only ever house individuals of a similar size (i.e. all juveniles, all sub-adults or all mature) for fear of harassment or predation. Finally, I also lost a few individuals to a build up of gas in the body cavity meaning the individuals float to the surface. I'm not 100% sure of the causes of this but I was successfully able to extract the gas on several occasions using a hypodermic needle. For most the bloating never reoccurred but for one or two it returned and the individuals became stressed again through their inability to rest on the bottom.

Therefore, my advice would be to check the water chemistry and try and reduce any possible causes of stress (e.g. remove the very small individuals, stock similar sizes and for near mature or mature individuals stock, at the very least, an equally sex ratio if not slightly female biased due to potential male harassment). Keep a close eye on behaviour at feeding times and should all else fail maybe employ infrared cameras to observe behaviour at night.

I hope this is useful. Let me know if you have any further questions.

Hi Hans,

As David has said, you should expect a certain amount of natural mortality potentially due to maternal deficiencies (I found that sudden embryo mortality similar to what you see was always more prevalent in embryos developing at the latter end of the laying cycle). I also found every aspect of breeding, laying and embryogenesis was quite temperature dependant, so another possibility of why the mortality rate increased towards the end of this cycle as temperatures were dropping and embryogenesis/ development was more protracted. Aside from these possibilities, I believe that the pups up to 6 months of age, particularly are very sensitive to bacterial infections and parasites, and therefore it is extremely important to not only keep size classes together (also as David suggested) and ensure that food is being distributed, equally available for (and actually eaten by)all animals, but also that you keep all tanks clean- which is a big task for these sharks. As their mouths are so small at this stage, there will inevitably be a lot of food waste in the environment, as well as other waste. It is important that you clean the tanks regularly as well as sterilise them properly to kill and remove parasites and bacteria from the environment. For me, this involved regular tank rotations and always having a spare tank sterilising that I could transfer sharks to as required.

Good luck!

Thank you all, for your helpful answers! We have dicided to put new eggs in a separate tank, treat them with a antifungal and anti-parasite wash and put in a chiller to keep temperature at 24 degrees centigrade and a algae filter to keep metabolites as low as possible. Any further measures we could take? Thanks again!

Has anyone considered salinity as an issue in this case? is it possible that the 6-month old juveniles needed a slightly different water chemistry at that stage of their life, or water with some certain specification of nutrient quality. i think is important to sort out issues as basic as water quality before exploring possible role of gene related issues.

Hi Hans

We had the same problems in Chile when we started to hatch Schroederichthys chilensis at our lab. Are you feeding these sharks with live preys? Is that shark natural inhabitant of that zone (I don't think so)? If not, you have to take care on the feeding, because they may need some nutrient composition that you can't supply with preys of Netherlands. Sometimes juveniles feed and hunt with no problems, but they died because that food may lack something they need.

I hope you can solve that. We solved that giving preys obtained in the same places where we found egg capsules aggregations in natural conditions.

Cheers!