Shark self-conservation

By Dave Armstrong - 08 Jan 2015 20:45:19 GMT
Shark self-conservation

This is the living pup of the brown-banded bamboo shark. Produced after its mother maintained spermatozoa for 4 years, this individual proves that shark conservation has additional help for much-needed success, at least in some species.Bamboo shark image; Credit: © California Academy of Sciences

The list of threatened species on Earth contains so many sharks and rays, it is deplorable. Here is one species that gives hope for the beleaguered and near-extinct. A West Pacific and Indian Ocean resident, Chiloscyllium punctatum is one species that is near-threatened by the aquarium industry. It is known as the brown-banded bamboo shark.

In California, the aquarium habit has suited it in a small way, as scientists have discovered it has a capacity for incredible sperm storage. Female animals cunningly maintain sperm in their bodies, from mantids and spiders to mammals such as marsupials, frogs and reptiles. But this shark holds the fishy record at least, 45 months after capture, the lady concerned produced 2 eggs in a mermaids purse. One viable one produced a healthy pup-shark that lives on to demonstrate the remarkable event.

People have noted this lack of need for male attention, as you would with any of the species concerned. Research has failed us, in not investigating this breakthrough for those worried about the near-threatened and the almost-extinct sharks. The Journal of Fish Biology publish the findings of Moises A. Bernal of the California Academy of Sciences and the University of Texas in the US and 5 colleagues, also from the Universities of California and Durham, UK.

Wild sharks now have the genetic possibility of preserving their sperm in a female for a similar period, but of course not many species may have this ability. Purely by a chance collection of purses, this one species has been found out. Potential fathers were restricted to one male cownose ray, but science will tell you how likely that mating would be. Genetics itself proved the mother was the one individual concerned (2 other females lived there) and that asexual reproduction had not occurred. Nobody thought of informing the father, from another aquarium, though his genetic material was discovered in the form of at least 32 alleles.

Ovulation in sharks such as this will depend less upon mating time, giving an opportunity to lay at opportunistic times and may result in greater species diversity. The power certainly lies with the female sex, who have been known to use parthenogenesis. This is why asexual reproduction was suspected. Shark conservation is vital to marine ecosystems of all types and this discovery gives some hope for certain species. Melbourne Aquarium has already produced pups of this same rare species using IVF, but this study ensures that the shark itself can manage quite well itself -– in some cases!

From threshers to blues and the latest hammerheads, check on our maze of stories on sharks, their fins, and especially, their conservation.